Science.gov

Sample records for advancing broadband availability

  1. 77 FR 38533 - Lifeline and Link Up Reform and Modernization, Advancing Broadband Availability Through Digital...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-28

    ... and Link Up Reform and Modernization, Advancing Broadband Availability Through Digital Literacy... March 2, 2012, (77 FR 12952). A correction to the final regulations in part 54 was published in the Federal Register March 30, 2012 (77 FR 19125). The regulations relate to the Federal...

  2. 77 FR 23630 - Lifeline and Link Up Reform and Modernization; Advancing Broadband Availability Through Digital...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-20

    ... Digital Literacy Training, et al., published at 77 FR 12952, March 2, 2012 in WC Docket Nos. 11-42, 03.... 2948] Lifeline and Link Up Reform and Modernization; Advancing Broadband Availability Through Digital Literacy Training, et al. AGENCY: Federal Communications Commission. ACTION: Final rule; petition...

  3. 77 FR 71712 - Lifeline and Link Up Reform and Modernization, Advancing Broadband Availability Through Digital...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-04

    ... and Link Up Reform and Modernization, Advancing Broadband Availability Through Digital Literacy... approval, as required by the Paperwork Reduction Act (PRA) of 1995 (44 U.S.C. 3501-3520), 77 FR 52718... requirements contained in the Commission's Order, FCC 12-11, published at 77 FR 12952, March 2, 2012. The...

  4. 77 FR 25609 - Lifeline and Link Up Reform and Modernization, Advancing Broadband Availability Through Digital...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-01

    ... and Link Up Reform and Modernization, Advancing Broadband Availability Through Digital Literacy... by the Paperwork Reduction Act (PRA) of 1995 (44 U.S.C. 3501-3520), 77 FR 13319, March 6, 2012. The..., 54.405(c), 54.407, 54.416, 54.417, 54.420(b), and 54.422, published at 77 FR 12952, March 2,...

  5. 77 FR 19125 - Lifeline and Link Up Reform and Modernization, Advancing Broadband Availability Through Digital...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-30

    ... and Link Up Reform and Modernization, Advancing Broadband Availability Through Digital Literacy... corrects errors in the DATES section of a Federal Register document (77 FR 12952, March 2, 2012) regarding... the DATES section of a Federal Register document, 77 FR 12952, March 2, 2012. This document...

  6. Funding Public Computing Centers: Balancing Broadband Availability and Expected Demand

    ERIC Educational Resources Information Center

    Jayakar, Krishna; Park, Eun-A

    2012-01-01

    The National Broadband Plan (NBP) recently announced by the Federal Communication Commission visualizes a significantly enhanced commitment to public computing centers (PCCs) as an element of the Commission's plans for promoting broadband availability. In parallel, the National Telecommunications and Information Administration (NTIA) has…

  7. Broadband Electromagnetic Follow-up of Advanced LIGO Sources

    NASA Astrophysics Data System (ADS)

    Singer, Leo; LIGO Scientific Collaboration; Virgo Collaboration

    2016-03-01

    Advanced LIGO began observing in September 2015 with over 3 times the distance reach (27 times the sensitive volume) of its previous configuration. Some gravitational-wave sources, particularly neutron star binary mergers, are expected to produce broadband electromagnetic transients which may be crucial to understanding the astrophysical context of these events. We have assembled a consortium of over 60 ground- and space-based gamma-ray, x-ray, optical, infrared, and radio facilities collaborating to search for broadband electromagnetic counterparts of gravitational-wave sources. In this talk, we describe the LIGO/Virgo EM follow-up program and the astronomical facilities that participated during this first LIGO observing run. Then, we survey the multi-wavelength observing campaigns embarked upon for specific gravitational-wave events. Finally, we discuss lessons learned and the way forward for joint GW-EM observations in an era of increasingly sensitive GW detectors.

  8. Broadband Electromagnetic Follow-up of Advanced LIGO Sources

    NASA Astrophysics Data System (ADS)

    Pound Singer, Leo

    2016-04-01

    Advanced LIGO began observing in September 2015 with over 3 times the distance reach (27 times the sensitive volume) of its previous configuration. Some gravitational-wave sources, particularly neutron star binary mergers, are expected to produce broadband electromagnetic transients which may be crucial to understanding the astrophysical context of these events. We have assembled a consortium of over 60 ground- and space-based gamma-ray, x-ray, optical, infrared, and radio facilities collaborating to search for broadband electromagnetic counterparts of gravitational-wave sources. In this talk, we describe the LIGO/Virgo EM follow-up program and the astronomical facilities that participated during this first LIGO observing run. Then, we survey the multi-wavelength observing campaigns embarked upon for specific gravitational-wave events. Finally, we discuss lessons learned and the way forward for joint GW-EM observations in an era of increasingly sensitive GW detectors.Submitted with The LIGO Scientific Collaboration and The Virgo Collaboration.

  9. 7 CFR 1738.11 - Availability of broadband service.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... rates, system latency, and data rate restrictions, is not satisfactory as determined by RUS. (c) All... area, and (B) A map of its service territory. (ii) The notice must satisfy all other requirements to... available to residential customers in the applicant's proposed service area. (b) RUS shall consider...

  10. Advanced Measurement Systems Available to PIWG Members

    NASA Technical Reports Server (NTRS)

    Anderson, Robert; Lei, Jih-Fen (Technical Monitor)

    2002-01-01

    It was developed advanced measurement technologies to meet NASA goals: reduce design cycle time, reduce emission, reduce testing time, increase safety. The technology are saving money. This technology are available now for technology transfer: optical diagnostics, the film technology and MEMS devices.

  11. 47 CFR 27.1250 - Transition of the 2150-2160/62 MHz band from the Broadband Radio Service to the Advanced Wireless...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... the Broadband Radio Service to the Advanced Wireless Service. 27.1250 Section 27.1250 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service Relocation Procedures for...

  12. 47 CFR 27.1250 - Transition of the 2150-2160/62 MHz band from the Broadband Radio Service to the Advanced Wireless...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... the Broadband Radio Service to the Advanced Wireless Service. 27.1250 Section 27.1250 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service Relocation Procedures for...

  13. 47 CFR 27.1250 - Transition of the 2150-2160/62 MHz band from the Broadband Radio Service to the Advanced Wireless...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... the Broadband Radio Service to the Advanced Wireless Service. 27.1250 Section 27.1250 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service Relocation Procedures for...

  14. Modeling of Broadband Liners Applied to the Advanced Noise Control Fan

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

    The broadband component of fan noise has grown in relevance with an increase in bypass ratio and incorporation of advanced fan designs. Therefore, while the attenuation of fan tones remains a major factor in engine nacelle acoustic liner design, the simultaneous reduction of broadband fan noise levels has received increased interest. As such, a previous investigation focused on improvements to an established broadband acoustic liner optimization process using the Advanced Noise Control Fan (ANCF) rig as a demonstrator. Constant-depth, double-degree of freedom and variable-depth, multi-degree of freedom liner designs were carried through design, fabrication, and testing. This paper addresses a number of areas for further research identified in the initial assessment of the ANCF study. Specifically, incident source specification and uncertainty in some aspects of the predicted liner impedances are addressed. This information is incorporated in updated predictions of the liner performance and comparisons with measurement are greatly improved. Results illustrate the value of the design process in concurrently evaluating the relative costs/benefits of various liner designs. This study also provides further confidence in the integrated use of duct acoustic propagation/radiation and liner modeling tools in the design and evaluation of novel broadband liner concepts for complex engine configurations.

  15. Improved Broadband Liner Optimization Applied to the Advanced Noise Control Fan

    NASA Technical Reports Server (NTRS)

    Nark, Douglas M.; Jones, Michael G.; Sutliff, Daniel L.; Ayle, Earl; Ichihashi, Fumitaka

    2014-01-01

    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 desirable. This paper describes improvements to a previously established broadband acoustic liner optimization process using the Advanced Noise Control Fan rig as a demonstrator. 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 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. Constant-depth, double-degree of freedom and variable-depth, multi-degree of freedom designs are carried through design, fabrication, and testing to validate the efficacy of the design process. Results illustrate the value of the design process in concurrently evaluating the relative costs/benefits of these liner designs. This study also provides an application for demonstrating the integrated use of duct acoustic propagation/radiation and liner modeling tools in the design and evaluation of novel broadband liner concepts for complex engine configurations.

  16. Advanced astigmatism-corrected Czerny-Turner imaging spectrometer in spectral broadband

    NASA Astrophysics Data System (ADS)

    Cong, Hai-fang

    2014-12-01

    This paper reports an advanced Czerny-Turner optical structure which is used for the application in imaging spectrometers. To obtain the excellent imaging quality, a cylindrical lens with a wedge angle is used between the focusing mirror and the imaging plane to remove astigmatism in broadband. It makes the advanced optical system presents high resolution over the full bandwidth and decreases the cost. An example of the imaging spectrometer in the waveband of 260nm~520nm has been designed to prove our theory. It yields the excellent modulation transfer functions (MTF) of all fields of view which are more than 0.75 over the broadband under the required Nyquist frequency (20lp/mm).

  17. Advancing drug availability-experiences from Africa.

    PubMed

    Powell, Richard A; Kaye, Richard Mugula; Ddungu, Henry; Mwangi-Powell, Faith

    2010-07-01

    International health and drug regulatory authorities acknowledge that analgesics (especially opioids) are insufficiently available for pain management in many countries. In Africa, reported morphine consumption is far below the global mean, with multiple factors hampering opioid supply. Since 2006, the African Palliative Care Association has hosted three regional drug availability workshops across the continent to address this issue. Using an interactive format, the workshops have identified country-specific barriers to opioid and other essential medication accessibility before supporting participants to develop action plans to address recognized impediments. Despite multiple challenges, a number of successes have arisen from the implementation of the plans. However, key issues remain, including the introduction of supportive policy environments, effective educational initiatives, and measures to address supply-chain obstacles impeding drug availability. PMID:20619205

  18. Significant technical advances in broadband seismic stations in the Lesser Antilles

    NASA Astrophysics Data System (ADS)

    Anglade, A.; Lemarchand, A.; Saurel, J.-M.; Clouard, V.; Bouin, M.-P.; De Chabalier, J.-B.; Tait, S.; Brunet, C.; Nercessian, A.; Beauducel, F.; Robertson, R.; Lynch, L.; Higgins, M.; Latchman, J.

    2015-04-01

    In the last few years, French West Indies observatories from the Institut de Physique du Globe de Paris (IPGP), in collaboration with The UWI Seismic Research Centre (SRC, University of West Indies), have modernized the Lesser Antilles Arc seismic and deformation monitoring network. 15 new, permanent stations have been installed that strengthen and expand its detection capabilities. The global network of the IPGP-SRC consortium is now composed of 20 modernized stations, all equipped with broadband seismometers, strong motion sensors, Global Positioning System (GPS) sensors and satellite communication for real-time data transfer. To enhance the sensitivity and reduce ambient noise, special efforts were made to improve the design of the seismic vault and the original Stuttgart shielding of the broadband seismometers (240 and 120s corner period). Tests were conducted for several months, involving different types of countermeasures, to achieve the highest performance level of the seismometers. GPS data, realtime and validated seismic data (only broadband) are now available from the IPGP data centre (http://centrededonnees.ipgp.fr/index.php?&lang=EN). This upgraded network feeds the Caribbean Tsunami Warning System supported by UNESCO and establishes a monitoring tool that produces high quality data for studying subduction and volcanic processes in the Lesser Antilles arc.

  19. Broadband Noise Prediction When Turbulence Simulation Is Available - Derivation of Formulation 2B and Its Statistical Analysis

    NASA Technical Reports Server (NTRS)

    Farassat, Fereidoun; Casper, Jay H.

    2012-01-01

    We show that a simple modification of Formulation 1 of Farassat results in a new analytic expression that is highly suitable for broadband noise prediction when extensive turbulence simulation is available. This result satisfies all the stringent requirements, such as permitting the use of the exact geometry and kinematics of the moving body, that we have set as our goal in the derivation of useful acoustic formulas for the prediction of rotating blade and airframe noise. We also derive a simple analytic expression for the autocorrelation of the acoustic pressure that is valid in the near and far fields. Our analysis is based on the time integral of the acoustic pressure that can easily be obtained at any resolution for any observer time interval and digitally analyzed for broadband noise prediction. We have named this result as Formulation 2B of Farassat. One significant consequence of Formulation 2B is the derivation of the acoustic velocity potential for the thickness and loading terms of the Ffowcs Williams-Hawkings (FW-H) equation. This will greatly enhance the usefulness of the Fast Scattering Code (FSC) by providing a high fidelity boundary condition input for scattering predictions.

  20. 47 CFR 27.1250 - Transition of the 2150-2160/62 MHz band from the Broadband Radio Service to the Advanced Wireless...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Transition of the 2150-2160/62 MHz band from the Broadband Radio Service to the Advanced Wireless Service. 27.1250 Section 27.1250 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service...

  1. Advanced Telecommunications in Rural America: The Challenge of Bringing Broadband Service to All Americans.

    ERIC Educational Resources Information Center

    National Telecommunications and Information Administration (DOC), Washington, DC.

    This report, in response to a request by 10 U.S. Senators examines the status of broadband deployment in the United States. The rate of deployment of broadband services will be key to future economic growth, particularly in rural areas far from urban and world markets. This report finds that rural areas, especially remote areas outside of towns,…

  2. 77 FR 12784 - Lifeline and Link Up Reform and Modernization, Advancing Broadband Availability Through Digital...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-02

    ... System (ECFS). See Electronic Filing of Documents in Rulemaking Proceedings, 63 FR 24121, May 1, 1998..., 76 FR 38040, June 29, 2011, which made clear that an eligible consumer may only receive one Lifeline... adoption gap. This Order complements the recent USF/ICC Transformation Order, 76 FR 76623, December 8,...

  3. 77 FR 12951 - Lifeline and Link Up Reform and Modernization, Advancing Broadband Availability Through Digital...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-02

    ... Commission adopted the Duplicative Program Payments Order, 76 FR 38040, June 29, 2011, which made clear that.../ICC Transformation Order, 76 FR 76623, December 8, 2011, which reoriented intercarrier compensation... Rulemaking (Lifeline and Link Up NPRM), 76 FR 16482, March 23, 2011. The Commission sought written...

  4. 47 CFR 27.1250 - Transition of the 2150-2160/62 MHz band from the Broadband Radio Service to the Advanced Wireless...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... the Broadband Radio Service to the Advanced Wireless Service. 27.1250 Section 27.1250 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS... Service to the Advanced Wireless Service. The 2150-2160/62 MHz band has been allocated for use by...

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

    NASA Astrophysics Data System (ADS)

    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.

  6. Advancements in Dual-Pump Broadband CARS for Supersonic Combustion Measurements

    NASA Technical Reports Server (NTRS)

    Tedder, Sarah Augusta Umberger

    2010-01-01

    Space- and time-resolved measurements of temperature and species mole fractions of nitrogen, oxygen, and hydrogen were obtained with a dual-pump coherent anti-Stokes Raman spectroscopy (CARS) system in hydrogen-fueled supersonic combustion free jet flows. These measurements were taken to provide time-resolved fluid properties of turbulent supersonic combustion for use in the creation and verification of computational fluid dynamic (CFD) models. CFD models of turbulent supersonic combustion flow currently facilitate the design of air-breathing supersonic combustion ramjet (scramjet) engines. Measurements were made in supersonic axi-symmetric free jets of two scales. First, the measurement system was tested in a laboratory environment using a laboratory-scale burner (approx.10 mm at nozzle exit). The flow structures of the laboratory-burner were too small to be resolved with the CARS measurements volume, but the composition and temperature of the jet allowed the performance of the system to be evaluated. Subsequently, the system was tested in a burner that was approximately 6 times larger, whose length scales are better resolved by the CARS measurement volume. During both these measurements, weaknesses of the CARS system, such as sensitivity to vibrations and beam steering and inability to measure temperature or species concentrations in hydrogen fuel injection regions were indentified. Solutions were then implemented in improved CARS systems. One of these improved systems is a dual-pump broadband CARS technique called, Width Increased Dual-pump Enhanced CARS (WIDECARS). The two lowest rotational energy levels of hydrogen detectable by WIDECARS are H2 S(3) and H2 S(4). The detection of these lines gives the system the capability to measure temperature and species concentrations in regions of the flow containing pure hydrogen fuel at room temperature. WIDECARS is also designed for measurements of all the major species (except water) in supersonic combustion flows

  7. Advancements in Dual-Pump Broadband CARS for Supersonic Combustion Measurements

    NASA Astrophysics Data System (ADS)

    Tedder, Sarah Augusta Umberger

    Space- and time-resolved measurements of temperature and species mole fractions of nitrogen, oxygen, and hydrogen were obtained with a dual-pump coherent anti-Stokes Raman spectroscopy (CARS) system in hydrogen-fueled supersonic combustion free jet flows. These measurements were taken to provide time-resolved fluid properties of turbulent supersonic combustion for use in the creation and verification of computational fluid dynamic (CFD) models. CFD models of turbulent supersonic combustion flow currently facilitate the design of air- breathing supersonic combustion ramjet (scramjet) engines. Measurements were made in supersonic axi-symmetric free jets of two scales. First, the measurement system was tested in a laboratory environment using a laboratory-scale burner (˜10 mm at nozzle exit). The flow structures of the laboratory-burner were too small to be resolved with the CARS measurements volume, but the composition and temperature of the jet allowed the performance of the system to be evaluated. Subsequently, the system was tested in a burner that was approximately 6 times larger, whose length scales are better resolved by the CARS measurement volume. During both these measurements, weaknesses of the CARS system, such as sensitivity to vibrations and beam steering and inability to measure temperature or species concentrations in hydrogen fuel injection regions were identified. Solutions were then implemented in improved CARS systems. One of these improved systems is a dual-pump broadband CARS technique called, Width Increased Dual-pump Enhanced CARS (WIDECARS). The two lowest rotational energy levels of hydrogen detectable by WIDECARS are H2 S(3) and H2 S(4). The detection of these lines gives the system the capability to measure temperature and species concentrations in regions of the flow containing pure hydrogen fuel at room temperature. WIDECARS is also designed for measurements of all the major species (except water) in supersonic combustion flows fueled

  8. Threaded molecular wires as building blocks for advanced polymer blends: WPLEDs, ultra-broadband optical amplifiers, multi color lasers

    NASA Astrophysics Data System (ADS)

    Brovelli, Sergio; Mroz, Marta; Sforazzini, Giuseppe; Virgili, Tersilla; Meinardi, Franco; Paleari, Alberto; Anderson, Harry L.; Lanzani, Guglielmo; Cacialli, Franco

    2011-03-01

    The ability to produce semiconducting polymer blends with white emission spectra, large emission cross sections and broad optical gain is critical to their application in white PLEDs, lasers and broadband amplifiers. Cyclodextrin-encapsulation is an effective means of suppressing detrimental intermolecular interactions, and energy transfer (ET) channels in polymer blends, thus enabling fabrication of white-PLEDs. We show that all such properties combine into a high impact photonic application: ultra-broad optical gain and two-color lasing in a binary polyrotaxane blend. We study the ultrafast photophysics of a blend of a conventional and an encapsulated polyfluorene. The morphology is investigated by microRaman imaging, AFM, and fluorescence lifetime microscopy. We ascribe the ultra-broad optical gain (>850 meV), and the simultaneous ASE for both constituents, to the dual effect of reduced polaron formation and suppressed ET. Our results demonstrate that polyrotaxanes could realistically represent the building blocks for advanced polymer blends with highly controlled optical properties, for applications in solid state lightning, lasers and photovoltaic technologies.

  9. ACTS broadband aeronautical experiment

    NASA Technical Reports Server (NTRS)

    Abbe, Brian S.; Jedrey, Thomas C.; Estabrook, Polly; Agan, Martin J.

    1993-01-01

    In the last decade, the demand for reliable data, voice, and video satellite communication links between aircraft and ground to improve air traffic control, airline management, and to meet the growing demand for passenger communications has increased significantly. It is expected that in the near future, the spectrum required for aeronautical communication services will grow significantly beyond that currently available at L-band. In anticipation of this, JPL is developing an experimental broadband aeronautical satellite communications system that will utilize NASA's Advanced Communications Technology Satellite (ACTS) as a satellite of opportunity and the technology developed under JPL's ACTS Mobile Terminal (AMT) Task to evaluate the feasibility of using K/Ka-band for these applications. The application of K/Ka-band for aeronautical satellite communications at cruise altitudes is particularly promising for several reasons: (1) the minimal amount of signal attenuation due to rain; (2) the reduced drag due to the smaller K/Ka-band antennas (as compared to the current L-band systems); and (3) the large amount of available bandwidth. The increased bandwidth available at these frequencies is expected to lead to significantly improved passenger communications - including full-duplex compressed video and multiple channel voice. A description of the proposed broadband experimental system will be presented including: (1) applications of K/Ka-band aeronautical satellite technology to U.S. industry; (2) the experiment objectives; (3) the experiment set-up; (4) experimental equipment description; and (5) industrial participation in the experiment and the benefits.

  10. 75 FR 33729 - Facilitating the Provision of Fixed and Mobile Broadband Access, Educational and Other Advanced...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-15

    ... Commission released the BRS/EBS Third Further Notice of Proposed Rulemaking (BRS/EBS Third FNPRM), 74 FR... corrects a clerical error in its rules governing the pre-transition frequency assignments for BRS Channel 1... (computer diskette, large print, audio cassette, and Braille) are available by contacting Brian Millin...

  11. Connecting America: The National Broadband Plan

    ERIC Educational Resources Information Center

    Federal Communications Commission, 2010

    2010-01-01

    In early 2009, Congress directed the Federal Communications Commission (FCC) to develop a National Broadband Plan to ensure every American has "access to broadband capability." Congress also required that this plan include a detailed strategy for achieving affordability and maximizing use of broadband to advance "consumer welfare, civic…

  12. Adjustable, Broadband, Selective Excitation with Uniform Phase

    NASA Astrophysics Data System (ADS)

    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.

  13. Adjustable, broadband, selective excitation with uniform phase.

    PubMed

    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. PMID:11945042

  14. Exploring Interstellar Chemistry with Broadband Reaction Screening

    NASA Astrophysics Data System (ADS)

    Zaleski, Daniel Paul

    Chirped pulse Fourier transform microwave (CP-FTMW) spectroscopy is a powerful technique for molecular detection and characterization. One of the strengths of this technique is the ability to analyze complex mixtures quickly and unambiguously. This capability is exploited utilizing a method called broadband reaction screening. Discussed in this thesis, chemical reactions in an electric discharge are monitored with broadband rotational spectroscopy, and the products are studied in the context of astrochemistry. Because of advancements in high-speed digital signal processing with increased data throughput, astrochemistry, as a field, is currently experiencing an emerging synergy between broadband laboratory spectra and broadband radio astronomical survey spectra. The availability of high quality radio astronomy survey spectra is expected to dramatically increase in the coming years, which in turn should provide the impetus for moving beyond the traditional "targeted search" model and instead focus on "reaction product screening". Since the two techniques characterize molecules in the same fashion, by their rotational spectra, directly comparing both types of broadband spectra may lead to a better understanding of the complex chemistry that occurs in the interstellar medium. Also discussed in this thesis is the development of two new CP-FTMW spectrometers operating in frequency ranges that are compatible with molecules of astronomical interest.

  15. Broadband radiometer

    DOEpatents

    Cannon, T.W.

    1994-07-26

    A broadband radiometer is disclosed including (a) an optical integrating sphere having generally spherical integrating chamber and an entry port for receiving light (e.g., having visible and ultraviolet fractions), (b) a first optical radiation detector for receiving light from the sphere and producing an electrical output signal corresponding to broadband radiation, (c) a second optical radiation detector for receiving light from the sphere and producing an electrical output signal corresponding to a predetermined wavelength fraction of the broadband radiation, and (d) an output for producing an electrical signal which is proportional to the difference between the two electrical output signals. The radiometer is very useful, for example, in measuring the absolute amount of ultraviolet light present in a given light sample. 8 figs.

  16. Broadband radiometer

    DOEpatents

    Cannon, Theodore W.

    1994-01-01

    A broadband radiometer including (a) an optical integrating sphere having a enerally spherical integrating chamber and an entry port for receiving light (e.g., having visible and ultraviolet fractions), (b) a first optical radiation detector for receiving light from the sphere and producing an electrical output signal corresponding to broadband radiation, (c) a second optical radiation detector for receiving light from the sphere and producing an electrical output signal corresponding to a predetermined wavelength fraction of the broadband radiation, and (d) an output for producing an electrical signal which is proportional to the difference between the two electrical output signals. The radiometer is very useful, for example, in measuring the absolute amount of ultraviolet light present in a given light sample.

  17. Temperature monitoring options available at the Idaho national laboratory advanced test reactor

    NASA Astrophysics Data System (ADS)

    Daw, J. E.; Rempe, J. L.; Knudson, D. L.; Unruh, T. C.; Chase, B. M.; Davis, K. L.; Palmer, A. J.

    2013-09-01

    As part of the Advanced Test Reactor National Scientific User Facility (ATR-NSUF) program, the Idaho National Laboratory (INL) has developed in-house capabilities to fabricate, test, and qualify new and enhanced temperature sensors for irradiation testing. Clearly, temperature sensor selection for irradiation tests will be determined based on the irradiation environment and budget. However, temperature sensors now offered by INL include a wide array of melt wires in small capsules, silicon carbide monitors, commercially available thermocouples, and specialized high temperature irradiation resistant thermocouples containing doped molybdenum and niobium alloy thermoelements. In addition, efforts have been initiated to develop and evaluate ultrasonic thermometers for irradiation testing. This array of temperature monitoring options now available to ATR and other Material and Test Reactor (MTR) users fulfills recent customer requests.

  18. 76 FR 32901 - The Provision of Fixed and Mobile Broadband Access, Educational and Other Advanced Services in...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-07

    ... available for inspection and copying during normal business hours in the FCC Reference Information Center... individual channels in the LBS and UBS in the post-transition band plan adopted by the Commission. 2. Today...) by filing paper copies. See Electronic Filing of Documents in Rulemaking Proceedings, 63 FR...

  19. ZnCdMgSe as a Materials Platform for Advanced Photonic Devices: Broadband Quantum Cascade Detectors and Green Semiconductor Disk Lasers

    NASA Astrophysics Data System (ADS)

    De Jesus, Joel

    The ZnCdMgSe family of II-VI materials has unique and promising characteristics that may be useful in practical applications. For example they can be grown lattice matched to InP substrates with lattice matched bandgaps that span from 2.1 to 3.5 eV, they can be successfully doped n-type, have a large conduction band offset (CBO) with no intervalley scattering present when strained, they have lower average phonon energies, and the InP lattice constant lies in the middle of the ZnSe and CdSe binaries compounds giving room to experiment with tensile and compressive stress. However they have not been studied in detail for use in practical devices. Here we have identified two types of devices that are being currently developed that benefit from the ZnCdMgSe-based material properties. These are the intersubband (ISB) quantum cascade (QC) detectors and optically pumped semiconductor lasers that emit in the visible range. The paucity for semiconductor lasers operating in the green-orange portion of the visible spectrum can be easily overcome with the ZnCdMgSe materials system developed in our research. The non-strain limited, large CBO available allows to expand the operating wavelength of ISB devices providing shorter and longer wavelengths than the currently commercially available devices. This property can also be exploited to develop broadband room temperature operation ISB detectors. The work presented here focused first on using the ZnCdMgSe-based material properties and parameter to understand and predict the interband and intersubband transitions of its heterostructures. We did this by studying an active region of a QC device by contactless electroreflectance, photoluminescence, FTIR transmittance and correlating the measurements to the quantum well structure by transfer matrix modeling. Then we worked on optimizing the ZnCdMgSe material heterostructures quality by studying the effects of growth interruptions on their optical and optoelectronic properties of

  20. Old Buildings Broadband Home Networks: Technologies and Services Overview

    NASA Astrophysics Data System (ADS)

    Fantacci, Romano; Pecorella, Tommaso; Micciullo, Luigia; Viti, Roberto; Pasquini, Vincenzo; Calì, Marco

    2014-05-01

    Internet broadband access is becoming a reality in many countries. To fully exploit the benefits from high-speed connection, both suitable home network connectivity and advanced services support have to be made available to the user. In this article, issues relative to the upgrade of existing home networks, particularly in old buildings, together with networking and security requirements are addressed, and possible solutions are proposed.

  1. TEMPERATURE MONITORING OPTIONS AVAILABLE AT THE IDAHO NATIONAL LABORATORY ADVANCED TEST REACTOR

    SciTech Connect

    J.E. Daw; J.L. Rempe; D.L. Knudson; T. Unruh; B.M. Chase; K.L Davis

    2012-03-01

    As part of the Advanced Test Reactor National Scientific User Facility (ATR NSUF) program, the Idaho National Laboratory (INL) has developed in-house capabilities to fabricate, test, and qualify new and enhanced sensors for irradiation testing. To meet recent customer requests, an array of temperature monitoring options is now available to ATR users. The method selected is determined by test requirements and budget. Melt wires are the simplest and least expensive option for monitoring temperature. INL has recently verified the melting temperature of a collection of materials with melt temperatures ranging from 100 to 1000 C with a differential scanning calorimeter installed at INL’s High Temperature Test Laboratory (HTTL). INL encapsulates these melt wires in quartz or metal tubes. In the case of quartz tubes, multiple wires can be encapsulated in a single 1.6 mm diameter tube. The second option available to ATR users is a silicon carbide temperature monitor. The benefit of this option is that a single small monitor (typically 1 mm x 1 mm x 10 mm or 1 mm diameter x 10 mm length) can be used to detect peak irradiation temperatures ranging from 200 to 800 C. Equipment has been installed at INL’s HTTL to complete post-irradiation resistivity measurements on SiC monitors, a technique that has been found to yield the most accurate temperatures from these monitors. For instrumented tests, thermocouples may be used. In addition to Type-K and Type-N thermocouples, a High Temperature Irradiation Resistant ThermoCouple (HTIR-TC) was developed at the HTTL that contains commercially-available doped molybdenum paired with a niobium alloy thermoelements. Long duration high temperature tests, in furnaces and in the ATR and other MTRs, demonstrate that the HTIR-TC is accurate up to 1800 C and insensitive to thermal neutron interactions. Thus, degradation observed at temperatures above 1100 C with Type K and N thermocouples and decalibration due to transmutation with tungsten

  2. Pantomime-Grasping: Advance Knowledge of Haptic Feedback Availability Supports an Absolute Visuo-Haptic Calibration

    PubMed Central

    Davarpanah Jazi, Shirin; Heath, Matthew

    2016-01-01

    An emerging issue in movement neurosciences is whether haptic feedback influences the nature of the information supporting a simulated grasping response (i.e., pantomime-grasping). In particular, recent work by our group contrasted pantomime-grasping responses performed with (i.e., PH+ trials) and without (i.e., PH− trials) terminal haptic feedback in separate blocks of trials. Results showed that PH− trials were mediated via relative visual information. In contrast, PH+ trials showed evidence of an absolute visuo-haptic calibration—a finding attributed to an error signal derived from a comparison between expected and actual haptic feedback (i.e., an internal forward model). The present study examined whether advanced knowledge of haptic feedback availability influences the aforementioned calibration process. To that end, PH− and PH+ trials were completed in separate blocks (i.e., the feedback schedule used in our group’s previous study) and a block wherein PH− and PH+ trials were randomly interleaved on a trial-by-trial basis (i.e., random feedback schedule). In other words, the random feedback schedule precluded participants from predicting whether haptic feedback would be available at the movement goal location. We computed just-noticeable-difference (JND) values to determine whether responses adhered to, or violated, the relative psychophysical principles of Weber’s law. Results for the blocked feedback schedule replicated our group’s previous work, whereas in the random feedback schedule PH− and PH+ trials were supported via relative visual information. Accordingly, we propose that a priori knowledge of haptic feedback is necessary to support an absolute visuo-haptic calibration. Moreover, our results demonstrate that the presence and expectancy of haptic feedback is an important consideration in contrasting the behavioral and neural properties of natural and simulated grasping. PMID:27199718

  3. System and Propagation Availability Analysis for NASA's Advanced Air Transportation Technologies

    NASA Technical Reports Server (NTRS)

    Ugweje, Okechukwu C.

    2000-01-01

    This report summarizes the research on the System and Propagation Availability Analysis for NASA's project on Advanced Air Transportation Technologies (AATT). The objectives of the project were to determine the communication systems requirements and architecture, and to investigate the effect of propagation on the transmission of space information. In this report, results from the first year investigation are presented and limitations are highlighted. To study the propagation links, an understanding of the total system architecture is necessary since the links form the major component of the overall architecture. This study was conducted by way of analysis, modeling and simulation on the system communication links. The overall goals was to develop an understanding of the space communication requirements relevant to the AATT project, and then analyze the links taking into consideration system availability under adverse atmospheric weather conditions. This project began with a preliminary study of the end-to-end system architecture by modeling a representative communication system in MATLAB SIMULINK. Based on the defining concepts, the possibility of computer modeling was determined. The investigations continue with the parametric studies of the communication system architecture. These studies were also carried out with SIMULINK modeling and simulation. After a series of modifications, two end-to-end communication links were identified as the most probable models for the communication architecture. Link budget calculations were then performed in MATHCAD and MATLAB for the identified communication scenarios. A remarkable outcome of this project is the development of a graphic user interface (GUI) program for the computation of the link budget parameters in real time. Using this program, one can interactively compute the link budget requirements after supplying a few necessary parameters. It provides a framework for the eventual automation of several computations

  4. Broadband noise of propellers and rotors

    NASA Astrophysics Data System (ADS)

    George, A. R.; Chou, S.-T.

    Three categories of rotor noise (discrete frequency noise, impulsive noise, and broadband noise) are described and a study made of broadband noise is reported. Broadband noise has a continuous spectrum and is caused by disturbances which are not precisely repeated at each blade revolution but are basically due to some sort of turbulence-blade interactions. Source mechanisms include: inflow turbulence noise, boundary layer trailing edge noise, tip vortex noise, and several uncommon mechanisms. Broadband noise analyses are reviewed and calculations based on various analyses are compared to each other and to some available experimental data. Several satisfactory analyses are discussed and their limitations are delineated. Twenty-two references are cited.

  5. Available evidence and new biological perspectives on medical treatment of advanced thymic epithelial tumors.

    PubMed

    Serpico, D; Trama, A; Haspinger, E R; Agustoni, F; Botta, L; Berardi, R; Palmieri, G; Zucali, P; Gallucci, R; Broggini, M; Gatta, G; Pastorino, U; Pelosi, G; de Braud, F; Garassino, M C

    2015-05-01

    Thymic epithelial tumors (TETs) are rare primary mediastinal tumors arising from thymic epithelium. Their rarity and complexity hinder investigations of their causes and therapy development. Here, we summarize the existing knowledge regarding medical treatment of these tumors, and thoroughly review the known genetic aberrations associated with TETs and the present status of potential biological treatments. Epidermal growth factor receptor (EGFR), stem-cell factor receptor, insulin-like growth factor-1 receptor (IGF1R), and vascular endothelial growth factors (VEGF-A, VEGF-B, and VEGF-2) are overexpressed in TETs. EGFR overexpression in TETs is associated with higher stage, and IGF1R overexpression has poor prognostic value. Data indicate that anti-IGF1R monoclonal antibodies, and inhibitors of angiogenesis, somatostatin receptors, histone deacetylase, mammalian target of rapamycin, and cyclin-dependent kinases may be active against TETs. Continued investigations in this field could lead to advancement of targeted and biological therapies for TETs. PMID:25411417

  6. AIRTV: Broadband Direct to Aircraft

    NASA Astrophysics Data System (ADS)

    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

  7. Advances in the genetic dissection of plant cell walls: tools and resources available in Miscanthus

    PubMed Central

    Slavov, Gancho; Allison, Gordon; Bosch, Maurice

    2013-01-01

    Tropical C4 grasses from the genus Miscanthus are believed to have great potential as biomass crops. However, Miscanthus species are essentially undomesticated, and genetic, molecular and bioinformatics tools are in very early stages of development. Furthermore, similar to other crops targeted as lignocellulosic feedstocks, the efficient utilization of biomass is hampered by our limited knowledge of the structural organization of the plant cell wall and the underlying genetic components that control this organization. The Institute of Biological, Environmental and Rural Sciences (IBERS) has assembled an extensive collection of germplasm for several species of Miscanthus. In addition, an integrated, multidisciplinary research programme at IBERS aims to inform accelerated breeding for biomass productivity and composition, while also generating fundamental knowledge. Here we review recent advances with respect to the genetic characterization of the cell wall in Miscanthus. First, we present a summary of recent and on-going biochemical studies, including prospects and limitations for the development of powerful phenotyping approaches. Second, we review current knowledge about genetic variation for cell wall characteristics of Miscanthus and illustrate how phenotypic data, combined with high-density arrays of single-nucleotide polymorphisms, are being used in genome-wide association studies to generate testable hypotheses and guide biological discovery. Finally, we provide an overview of the current knowledge about the molecular biology of cell wall biosynthesis in Miscanthus and closely related grasses, discuss the key conceptual and technological bottlenecks, and outline the short-term prospects for progress in this field. PMID:23847628

  8. Advanced Monitoring to Improve Combustion Turbine/Combined Cycle Reliability, Availability & Maintainability

    SciTech Connect

    Leonard Angello

    2005-09-30

    Power generators are concerned with the maintenance costs associated with the advanced turbines that they are purchasing. Since these machines do not have fully established Operation and Maintenance (O&M) track records, power generators face financial risk due to uncertain future maintenance costs. This risk is of particular concern, as the electricity industry transitions to a competitive business environment in which unexpected O&M costs cannot be passed through to consumers. These concerns have accelerated the need for intelligent software-based diagnostic systems that can monitor the health of a combustion turbine in real time and provide valuable information on the machine's performance to its owner/operators. EPRI, Impact Technologies, Boyce Engineering, and Progress Energy have teamed to develop a suite of intelligent software tools integrated with a diagnostic monitoring platform that, in real time, interpret data to assess the 'total health' of combustion turbines. The 'Combustion Turbine Health Management System' (CTHMS) will consist of a series of 'Dynamic Link Library' (DLL) programs residing on a diagnostic monitoring platform that accepts turbine health data from existing monitoring instrumentation. CTHMS interprets sensor and instrument outputs, correlates them to a machine's condition, provide interpretative analyses, project servicing intervals, and estimate remaining component life. In addition, the CTHMS enables real-time anomaly detection and diagnostics of performance and mechanical faults, enabling power producers to more accurately predict critical component remaining useful life and turbine degradation.

  9. The Advanced Test Reactor Irradiation Capabilities Available as a National Scientific User Facility

    SciTech Connect

    S. Blaine Grover

    2008-09-01

    The Advanced Test Reactor (ATR) is one of the world’s premiere test reactors for performing long term, high flux, and/or large volume irradiation test programs. The ATR is a very versatile facility with a wide variety of experimental test capabilities for providing the environment needed in an irradiation experiment. These capabilities include simple capsule experiments, instrumented and/or temperature-controlled experiments, and pressurized water loop experiment facilities. Monitoring systems have also been utilized to monitor different parameters such as fission gases for fuel experiments, to measure specimen performance during irradiation. ATR’s control system provides a stable axial flux profile throughout each reactor operating cycle, and allows the thermal and fast neutron fluxes to be controlled separately in different sections of the core. The ATR irradiation positions vary in diameter from 16 mm to 127 mm over an active core height of 1.2 m. This paper discusses the different irradiation capabilities with examples of different experiments and the cost/benefit issues related to each capability. The recent designation of ATR as a national scientific user facility will make the ATR much more accessible at very low to no cost for research by universities and possibly commercial entities.

  10. 75 FR 56057 - Proposed Information Collection; Comment Request; Broadband Technology Opportunities Program Post...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-15

    ... Development Grant Program (Broadband Mapping Program) authorized by the Broadband Data Improvement Act. The Broadband Mapping Program is designed to support the development and maintenance of a nationwide broadband... made available for competitive grants for innovative programs to encourage sustainable adoption...

  11. Advances in soil erosion modelling through remote sensing data availability at European scale

    NASA Astrophysics Data System (ADS)

    Panagos, Panos; Karydas, Christos; Borrelli, Pasqualle; Ballabio, Cristiano; Meusburger, Katrin

    2014-08-01

    Under the European Union's Thematic Strategy for Soil Protection, the European Commission's Directorate-General for the Environment (DG Environment) has identified the mitigation of soil losses by erosion as a priority area. Policy makers call for an overall assessment of soil erosion in their geographical area of interest. They have asked that risk areas for soil erosion be mapped under present land use and climate conditions, and that appropriate measures be taken to control erosion within the legal and social context of natural resource management. Remote sensing data help to better assessment of factors that control erosion, such as vegetation coverage, slope length and slope angle. In this context, the data availability of remote sensing data during the past decade facilitates the more precise estimation of soil erosion risk. Following the principles of the Universal Soil Loss Equation (USLE), various options to calculate vegetative cover management (C-factor) have been investigated. The use of the CORINE Land Cover dataset in combination with lookup table values taken from the literature is presented as an option that has the advantage of a coherent input dataset but with the drawback of static input. Recent developments in the Copernicus programme have made detailed datasets available on land cover, leaf area index and base soil characteristics. These dynamic datasets allow for seasonal estimates of vegetation coverage, and their application in the G2 soil erosion model which represents a recent approach to the seasonal monitoring of soil erosion. The use of phenological datasets and the LUCAS land use/cover survey are proposed as auxiliary information in the selection of the best methodology.

  12. The Broadband Buzz.

    ERIC Educational Resources Information Center

    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)

  13. ATST visible broadband imager

    NASA Astrophysics Data System (ADS)

    McBride, William R.; Wöger, Friedrich; Hegwer, Steve L.; Ferayorni, Andrew; Gregory, B. Scott

    2012-09-01

    The Advanced Technology Solar Telescope (ATST) is a 4 meter class telescope for observation of the solar atmosphere currently in the construction phase. The Visible Broadband Imager (VBI) is a diffraction limited imaging instrument planned to be the first-light instrument in the ATST instrumentation suite. The VBI is composed of two branches, the "VBI blue" and the "VBI red", and uses state-of-the-art narrow bandwidth interference filters and two custom designed high speed filter wheels to take bursts of images that will be re-constructed using a Graphics Processing Unit (GPU) optimized near-real-time speckle image reconstruction engine. At first light, the VBI instrument will produce diffraction-limited movies of solar activity at eight discrete wavelengths with a field of view of 2 arc minutes square. In this contribution, the VBI design team will discuss the capabilities of the VBI and describe the design of the instrument, highlighting the unique challenges faced in the development of this unique instrument.

  14. UHB engine fan broadband noise reduction study

    NASA Astrophysics Data System (ADS)

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

    1995-06-01

    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.

  15. UHB Engine Fan Broadband Noise Reduction Study

    NASA Technical Reports Server (NTRS)

    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.

  16. Broadband patterned magnetic microwave absorber

    SciTech Connect

    Li, Wei; Wu, Tianlong; Wang, Wei; Guan, Jianguo; Zhai, Pengcheng

    2014-07-28

    It is a tough task to greatly improve the working bandwidth for the traditional flat microwave absorbers because of the restriction of available material parameters. In this work, a simple patterning method is proposed to drastically broaden the absorption bandwidth of a conventional magnetic absorber. As a demonstration, an ultra-broadband microwave absorber with more than 90% absorption in the frequency range of 4–40 GHz is designed and experimentally realized, which has a thin thickness of 3.7 mm and a light weight equivalent to a 2-mm-thick flat absorber. In such a patterned absorber, the broadband strong absorption is mainly originated from the simultaneous incorporation of multiple λ/4 resonances and edge diffraction effects. This work provides a facile route to greatly extend the microwave absorption bandwidth for the currently available absorbing materials.

  17. Timing of Therapies in the Multidisciplinary Treatment of Locally Advanced Rectal Cancer: Available Evidence and Implications for Routine Practice.

    PubMed

    Sclafani, Francesco; Chau, Ian

    2016-07-01

    A multimodality disciplinary approach is paramount for the management of locally advanced rectal cancer. Over the last decade, (chemo)radiotherapy followed by surgery plus or minus adjuvant chemotherapy has represented the mainstay of treatment for this disease. Nevertheless, robust evidence suggesting the optimal timing and sequence of therapies in this setting has been overall limited. A number of questions are still unsolved including the length of the interval between neoadjuvant radiotherapy and surgery or the timing of systemic chemotherapy. Interestingly, emerging data support the contention that altering sequence or timing or both of the components of this multimodality approach may provide an opportunity to implement treatment strategies that far better address the risk and expectations of individual patients. In this article, we review the available evidence on timing of therapies in the multidisciplinary treatment of locally advanced rectal cancer and discuss the potential implications for routine practice that may derive from a change of the currently accepted treatment paradigm. PMID:27238468

  18. Broadband Rotational Spectroscopy

    NASA Astrophysics Data System (ADS)

    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

  19. Digital Dead Ends along Alaska's Information Highway: Broadband Access for Students and Teachers in Alaska's High School One-to-One Laptop Programs

    ERIC Educational Resources Information Center

    Lloyd, Pamela Jo

    2012-01-01

    This dissertation analyzes the potential impact community broadband availability has on personal and classroom levels of technology adoption for high school students and teachers in Alaska. Community broadband availability was defined as, (a) terrestrial broadband availability; (b) satellite broadband availability; and (c) no broadband available.…

  20. Advanced Doppler tracking experiments

    NASA Technical Reports Server (NTRS)

    Armstrong, J. W.

    1989-01-01

    The Doppler tracking method is currently the only technique available for broadband gravitational wave searches in the approx. 10(exp -4) to 10(exp -1) Hz low frequency band. A brief review is given of the Doppler method, a discussion of the main noise sources, and a review of experience with current spacecraft and the prospects for sensitivity improvements in an advanced Doppler tracking experiment.

  1. Freely-tunable broadband polarization rotator for terahertz waves

    NASA Astrophysics Data System (ADS)

    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.

  2. Broadband accelerator control network

    SciTech Connect

    Skelly, J.; Clifford, T.; Frankel, R.

    1983-01-01

    A broadband data communications network has been implemented at BNL for control of the Alternating Gradient Synchrotron (AG) proton accelerator, using commercial CATV hardware, dual coaxial cables as the communications medium, and spanning 2.0 km. A 4 MHz bandwidth Digital Control channel using CSMA-CA protocol is provided for digital data transmission, with 8 access nodes available over the length of the RELWAY. Each node consists of an rf modem and a microprocessor-based store-and-forward message handler which interfaces the RELWAY to a branch line implemented in GPIB. A gateway to the RELWAY control channel for the (preexisting) AGS Computerized Accelerator Operating system has been constructed using an LSI-11/23 microprocessor as a device in a GPIB branch line. A multilayer communications protocol has been defined for the Digital Control Channel, based on the ISO Open Systems Interconnect layered model, and a RELWAY Device Language defined as the required universal language for device control on this channel.

  3. Delivery of satellite based broadband services

    NASA Astrophysics Data System (ADS)

    Chandrasekhar, M. G.; Venugopal, D.

    2007-06-01

    Availability of speedy communication links to individuals and organizations is essential to keep pace with the business and social requirements of this modern age. While the PCs have been continuously growing in processing speed and memory capabilities, the availability of broadband communication links still has not been satisfactory in many parts of the world. Recognizing the need to give fillip to the growth of broadband services and improve the broadband penetration, the telecom policies of different counties have placed special emphasis on the same. While emphasis is on the use of fiber optic and copper in local loop, satellite communications systems will play an important role in quickly establishing these services in areas where fiber and other communication systems are not available and are not likely to be available for a long time to come. To make satellite communication systems attractive for the wide spread of these services in a cost effective way special emphasis has to be given on factors affecting the cost of the bandwidth and the equipment. As broadband services are bandwidth demanding, use of bandwidth efficient modulation technique and suitable system architecture are some of the important aspects that need to be examined. Further there is a need to re-look on how information services are provided keeping in view the user requirements and broadcast capability of satellite systems over wide areas. This paper addresses some of the aspects of delivering broadband services via satellite taking Indian requirement as an example.

  4. 75 FR 3791 - Broadband Technology Opportunities Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-22

    ... Availability and Solicitation of Applications, 74 FR 32545 (July 8, 2009). B. Round One In response to the... demand for broadband services. \\7\\ Notice of Funds Availability and Solicitation of Applications, 74 FR... topics, and these comments have played an important role in developing this NOFA. For further...

  5. Passive broadband acoustic thermometry

    NASA Astrophysics Data System (ADS)

    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.

  6. Broadband Liner Optimization for the Source Diagnostic Test Fan

    NASA Technical Reports Server (NTRS)

    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.

  7. ADVANCED MONITORING TO IMPROVE COMBUSTION TURBINE/COMBINED CYCLE CT/(CC) RELIABILITY, AVAILABILITY AND MAINTAINABILITY (RAM)

    SciTech Connect

    Leonard Angello

    2004-09-30

    Power generators are concerned with the maintenance costs associated with the advanced turbines that they are purchasing. Since these machines do not have fully established operation and maintenance (O&M) track records, power generators face financial risk due to uncertain future maintenance costs. This risk is of particular concern, as the electricity industry transitions to a competitive business environment in which unexpected O&M costs cannot be passed through to consumers. These concerns have accelerated the need for intelligent software-based diagnostic systems that can monitor the health of a combustion turbine in real time and provide valuable information on the machine's performance to its owner/operators. EPRI, Impact Technologies, Boyce Engineering, and Progress Energy have teamed to develop a suite of intelligent software tools integrated with a diagnostic monitoring platform that will, in real time, interpret data to assess the ''total health'' of combustion turbines. The Combustion Turbine Health Management System (CTHM) will consist of a series of dynamic link library (DLL) programs residing on a diagnostic monitoring platform that accepts turbine health data from existing monitoring instrumentation. The CTHM system will be a significant improvement over currently available techniques for turbine monitoring and diagnostics. CTHM will interpret sensor and instrument outputs, correlate them to a machine's condition, provide interpretative analyses, project servicing intervals, and estimate remaining component life. In addition, it will enable real-time anomaly detection and diagnostics of performance and mechanical faults, enabling power producers to more accurately predict critical component remaining useful life and turbine degradation.

  8. ADVANCED MONITORING TO IMPROVE COMBUSTION TURBINE/COMBINED CYCLE CT/(CC) RELIABILITY, AVAILABILITY AND MAINTAINABILITY (RAM)

    SciTech Connect

    Leonard Angello

    2004-03-31

    Power generators are concerned with the maintenance costs associated with the advanced turbines that they are purchasing. Since these machines do not have fully established operation and maintenance (O&M) track records, power generators face financial risk due to uncertain future maintenance costs. This risk is of particular concern, as the electricity industry transitions to a competitive business environment in which unexpected O&M costs cannot be passed through to consumers. These concerns have accelerated the need for intelligent software-based diagnostic systems that can monitor the health of a combustion turbine in real time and provide valuable information on the machine's performance to its owner/operators. EPRI, Impact Technologies, Boyce Engineering, and Progress Energy have teamed to develop a suite of intelligent software tools integrated with a diagnostic monitoring platform that will, in real time, interpret data to assess the ''total health'' of combustion turbines. The Combustion Turbine Health Management System (CTHM) will consist of a series of dynamic link library (DLL) programs residing on a diagnostic monitoring platform that accepts turbine health data from existing monitoring instrumentation. The CTHM system will be a significant improvement over currently available techniques for turbine monitoring and diagnostics. CTHM will interpret sensor and instrument outputs, correlate them to a machine's condition, provide interpretative analyses, project servicing intervals, and estimate remaining component life. In addition, it will enable real-time anomaly detection and diagnostics of performance and mechanical faults, enabling power producers to more accurately predict critical component remaining useful life and turbine degradation.

  9. Broadband Analysis of Bioagents by Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Fenselau, Catherine; Wynne, Colin; Edwards, Nathan

    Mass spectrometry was first reported to provide analysis of intact metabolite biomarkers from whole cells in 1975.1 Since then advances in ionization techniques have extended our capabilities to polar lipids and, eventually, to proteins.2, 3 Mass spectrometry provides a broadband detection system, which, however, has great specificity. Bioinformatics plays an important role in providing flexible and rapid characterization of species, based on protein and peptide mass spectra collected in the field.

  10. Broadband External-Cavity Diode Laser

    NASA Technical Reports Server (NTRS)

    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.

  11. ADVANCED MONITORING TO IMPROVE COMBUSTION TURBINE/COMBINED CYCLE CT/(CC) RELIABILITY, AVAILABILITY AND MAINTAINABILITY (RAM)

    SciTech Connect

    Leonard Angello

    2003-09-30

    Power generators are concerned with the maintenance costs associated with the advanced turbines that they are purchasing. Since these machines do not have fully established operation and maintenance (O&M) track records, power generators face financial risk due to uncertain future maintenance costs. This risk is of particular concern, as the electricity industry transitions to a competitive business environment in which unexpected O&M costs cannot be passed through to consumers. These concerns have accelerated the need for intelligent software-based diagnostic systems that can monitor the health of a combustion turbine in real time and provide valuable information on the machine's performance to its owner/operators. Such systems would interpret sensor and instrument outputs, correlate them to the machine's condition, provide interpretative analyses, forward projections of servicing intervals, estimate remaining component life, and identify faults. EPRI, Impact Technologies, Boyce Engineering, and Progress Energy have teamed to develop a suite of intelligent software tools integrated with a diagnostic monitoring platform that will, in real time, interpret data to assess the ''total health'' of combustion turbines. The Combustion Turbine Health Management System (CTHM) will consist of a series of dynamic link library (DLL) programs residing on a diagnostic monitoring platform that accepts turbine health data from existing monitoring instrumentation. The CTHM system will be a significant improvement over currently available techniques for turbine monitoring and diagnostics. CTHM will interpret sensor and instrument outputs, correlate them to a machine's condition, provide interpretative analyses, project servicing intervals, and estimate remaining component life. In addition, it will enable real-time anomaly detection and diagnostics of performance and mechanical faults, enabling power producers to more accurately predict critical component remaining useful life and

  12. Management practices for end-of-life cathode ray tube glass: Review of advances in recycling and best available technologies.

    PubMed

    Iniaghe, Paschal O; Adie, Gilbert U

    2015-11-01

    Cathode ray tubes are image display units found in computer monitors and televisions. In recent years, cathode ray tubes have been generated as waste owing to the introduction of newer and advanced technologies in image displays, such as liquid crystal displays and high definition televisions, among others. Generation and subsequent disposal of end-of-life cathode ray tubes presents a challenge owing to increasing volumes and high lead content embedded in the funnel and neck sections of the glass. Disposal in landfills and open dumping are anti-environmental practices considering the large-scale contamination of environmental media by the potential of toxic metals leaching from glass. Mitigating such environmental contamination will require sound management strategies that are environmentally friendly and economically feasible. This review covers existing and emerging management practices for end-of-life cathode ray tubes. An in-depth analysis of available technologies (glass smelting, detoxification of cathode ray tube glass, lead extraction from cathode ray tube glass) revealed that most of the techniques are environmentally friendly, but are largely confined to either laboratory scale, or are often limited owing to high cost to mount, or generate secondary pollutants, while a closed-looped method is antiquated. However, recycling in cementitious systems (cement mortar and concrete) gives an added advantage in terms of quantity of recyclable cathode ray tube glass at a given time, with minimal environmental and economic implications. With significant quantity of waste cathode ray tube glass being generated globally, cementitious systems could be economically and environmentally acceptable as a sound management practice for cathode ray tube glass, where other technologies may not be applicable. PMID:26463115

  13. 76 FR 13797 - Rural Broadband Access Loans and Loan Guarantees Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-14

    ...; ] DEPARTMENT OF AGRICULTURE Rural Utilities Service Rural Broadband Access Loans and Loan Guarantees Program... (FY) 2011 for the Rural Broadband Access Loan and Loan Guarantee program (the Broadband Program), subject to the availability of funding. This notice is being issued prior to passage of a...

  14. 75 FR 27984 - Broadband Technology Opportunities Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-19

    ... National Telecommunications and Information Administration RIN 0660-ZA28 Broadband Technology Opportunities... Applications, 75 FR 3792 (Jan. 22, 2010). \\2\\ Notice of Funds Availability; Extension of Application Closing Deadline for Comprehensive Community Infrastructure (CCI) Projects, 75 FR 10464 (Mar. 8, 2010); Notice...

  15. 75 FR 6627 - Broadband Technology Opportunities Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-10

    .../ . SUPPLEMENTARY INFORMATION: On January 22, 2010, NTIA published a Notice of Funds Availability (NOFA) (75 FR 3792... National Telecommunications and Information Administration RIN 0660-ZA28 Broadband Technology Opportunities Program AGENCY: National Telecommunications and Information Administration, U.S. Department of...

  16. High accuracy broadband infrared spectropolarimetry

    NASA Astrophysics Data System (ADS)

    Krishnaswamy, Venkataramanan

    Mueller matrix spectroscopy or Spectropolarimetry combines conventional spectroscopy with polarimetry, providing more information than can be gleaned from spectroscopy alone. Experimental studies on infrared polarization properties of materials covering a broad spectral range have been scarce due to the lack of available instrumentation. This dissertation aims to fill the gap by the design, development, calibration and testing of a broadband Fourier Transform Infra-Red (FT-IR) spectropolarimeter. The instrument operates over the 3-12 mum waveband and offers better overall accuracy compared to the previous generation instruments. Accurate calibration of a broadband spectropolarimeter is a non-trivial task due to the inherent complexity of the measurement process. An improved calibration technique is proposed for the spectropolarimeter and numerical simulations are conducted to study the effectiveness of the proposed technique. Insights into the geometrical structure of the polarimetric measurement matrix is provided to aid further research towards global optimization of Mueller matrix polarimeters. A high performance infrared wire-grid polarizer is characterized using the spectropolarimeter. Mueller matrix spectrum measurements on Penicillin and pine pollen are also presented.

  17. Pacific Array (Transportable Broadband Ocean Floor Array)

    NASA Astrophysics Data System (ADS)

    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.

  18. Broadband stimulated Raman backscattering

    NASA Astrophysics Data System (ADS)

    Landgraf, B.; Aurand, B.; Lehmann, G.; Gangolf, T.; Schnell, M.; Kühl, T.; Spielmann, C.

    2016-07-01

    Broadband amplification employing stimulated Raman backscattering is demonstrated. Using seed pulses with a bandwidth of about 200 nm, we study the amplification in a wide spectral range in a single laser shot. With chirped pump pulses and a Ne gas jet, we observed under optimized conditions, amplification in a range of about 80 nm, which is sufficient to support the amplification of sub-20 fs pulses. This broad amplification range is also in excellent agreement with PIC simulations. The conversion efficiency is at certain wavelengths as high as 1.2% and was measured to be better than 6 × 10‑3 on average.

  19. The GEOSCOPE broadband seismic observatory

    NASA Astrophysics Data System (ADS)

    Douet, Vincent; Vallée, Martin; Zigone, Dimitri; Bonaimé, Sébastien; Stutzmann, Eléonore; Maggi, Alessia; Pardo, Constanza; Bernard, Armelle; Leroy, Nicolas; Pesqueira, Frédéric; Lévêque, Jean-Jacques; Thoré, Jean-Yves; Bes de Berc, Maxime; Sayadi, Jihane

    2016-04-01

    The GEOSCOPE observatory has provided continuous broadband data to the scientific community for the past 34 years. The 31 operational GEOSCOPE stations are installed in 17 countries, across all continents and on islands throughout the oceans. They are equipped with three component very broadband seismometers (STS1, T240 or STS2) and 24 or 26 bit digitizers (Q330HR). Seismometers are installed with warpless base plates, which decrease long period noise on horizontal components by up to 15dB. All stations send data in real time to the IPGP data center, which transmits them automatically to other data centers (FDSN/IRIS-DMC and RESIF) and tsunami warning centers. In 2016, three stations are expected to be installed or re-installed: in Western China (WUS station), in Saint Pierre and Miquelon Island (off the East coast of Canada) and in Walis and Futuna (SouthWest Pacific Ocean). The waveform data are technically validated by IPGP (25 stations) or EOST (6 stations) in order to check their continuity and integrity. Scientific data validation is also performed by analyzing seismic noise level of the continuous data and by comparing real and synthetic earthquake waveforms (body waves). After these validations, data are archived by the IPGP data center in Paris. They are made available to the international scientific community through different interfaces (see details on http://geoscope.ipgp.fr). Data are duplicated at the FDSN/IRIS-DMC data center and a similar duplication at the French national data center RESIF will be operational in 2016. The GEOSCOPE broadband seismic observatory also provides near-real time information on global moderate-to-large seismicity (above magnitude 5.5-6) through the automated application of the SCARDEC method (Vallée et al., 2011). By using global data from the FDSN - in particular from GEOSCOPE and IRIS/USGS stations -, earthquake source parameters (depth, moment magnitude, focal mechanism, source time function) are determined about 45

  20. 25 CFR 170.616 - How are advance payments made when additional IRR Program funds are made available after...

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... self-governance agreement? When additional IRR Program funds are available, following the procedures in 25 CFR 1000.104, tribes can request to use the additional funds for IRR Program activities or... funds are made available after execution of the self-governance agreement? 170.616 Section...

  1. 25 CFR 170.616 - How are advance payments made when additional IRR Program funds are made available after...

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... self-governance agreement? When additional IRR Program funds are available, following the procedures in 25 CFR 1000.104, tribes can request to use the additional funds for IRR Program activities or... funds are made available after execution of the self-governance agreement? 170.616 Section...

  2. Broadband pendulum energy harvester

    NASA Astrophysics Data System (ADS)

    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.

  3. What Broadband Means for Schools.

    ERIC Educational Resources Information Center

    Moore, Bob

    2001-01-01

    Explains what a computer network broadband connection is and how having one benefits educational facilities that have implemented telecommunications. The importance of using an application service provider is discussed along with suggestions to help schools get started in adopting broadband communications. (GR)

  4. Estimation of broadband surface emissivity from narrowband emissivities.

    PubMed

    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. Broadband ringdown spectral photography.

    PubMed

    Scherer, J J; Paul, J B; Jiao, H; O'Keefe, A

    2001-12-20

    A new technique that enables frequency-resolved cavity ringdown absorption spectra to be obtained over a large optical bandwidth by a single laser shot is described. The technique, ringdown spectral photography (RSP), simultaneously employs two key principles to record the time and frequency response of an optical cavity along orthogonal axes of a CCD array detector. Previously, the principles employed in RSP were demonstrated with narrow-band laser light that was scanned in frequency [Chem. Phys. Lett. 292, 143 (1998)]. Here, the RSP method is demonstrated using single pulses of broadband visible laser light. The ability to obtain broad as well as rotationally resolved spectra over a large bandwidth with high sensitivity is demonstrated. PMID:18364983

  6. Metasurface Broadband Solar Absorber

    DOE PAGESBeta

    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

    Here, 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. Moreover, 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 distributionsmore » to elucidate how the absorption occurs within the metasurface structure.« less

  7. Metasurface Broadband Solar Absorber

    PubMed Central

    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

  8. Metasurface Broadband Solar Absorber

    NASA Astrophysics Data System (ADS)

    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.

  9. Metasurface Broadband Solar Absorber.

    PubMed

    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

  10. Metamaterial broadband angular selectivity

    NASA Astrophysics Data System (ADS)

    Shen, Yichen; Ye, Dexin; Wang, Li; Celanovic, Ivan; Ran, Lixin; Joannopoulos, John D.; Soljačić, Marin

    2014-09-01

    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.

  11. K/Ka-band Antenna for Broadband Aeronautical Mobile Application

    NASA Technical Reports Server (NTRS)

    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).

  12. AIRTV: Broadband Direct to Aircraft

    NASA Astrophysics Data System (ADS)

    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

  13. Broadband and ultra-broadband modular half-wave plates

    NASA Astrophysics Data System (ADS)

    Dimova, Emiliya; Huang, Wei; Popkirov, George; Rangelov, Andon; Kyoseva, Elica

    2016-05-01

    We experimentally demonstrate broadband and ultra-broadband spectral bandwidth modular half-wave plates. Both modular devices comprise an array of rotated single half-wave plates (HWPs), whereby for broadband and ultra-broadband performance we use standard and commercial achromatic HWPs, respectively. The bandwidth of the modular HWPs depends on the number N of individual HWPs used and in this paper we experimentally investigate this for N = { 3 , 5 , 7 , 9 }. The elements in the arrays are rotated at specific angles with respect to their fast-polarization axes, independent of the nature of the birefringent material. We find the rotation angles using an analogy to the technique of composite pulses, which is widely used for control in nuclear magnetic resonance.

  14. Broadband Achromatic Telecentric Lens

    NASA Technical Reports Server (NTRS)

    Mouroulis, Pantazis

    2007-01-01

    A new type of lens design features broadband achromatic performance as well as telecentricity, using a minimum number of spherical elements. With appropriate modifications, the lens design form can be tailored to cover the range of response of the focal-plane array, from Si (400-1,000 nm) to InGaAs (400-1,700 or 2,100 nm) or InSb/HgCdTe reaching to 2,500 nm. For reference, lenses typically are achromatized over the visible wavelength range of 480-650 nm. In remote sensing applications, there is a need for broadband achromatic telescopes, normally satisfied with mirror-based systems. However, mirror systems are not always feasible due to size or geometry restrictions. They also require expensive aspheric surfaces. Non-obscured mirror systems can be difficult to align and have a limited (essentially one-dimensional) field of view. Centrally obscured types have a two-dimensional but very limited field in addition to the obscuration. Telecentricity is a highly desirable property for matching typical spectrometer types, as well as for reducing the variation of the angle of incidence and cross-talk on the detector for simple camera types. This rotationally symmetric telescope with no obscuration and using spherical surfaces and selected glass types fills a need in the range of short focal lengths. It can be used as a compact front unit for a matched spectrometer, as an ultra-broadband camera objective lens, or as the optics of an integrated camera/spectrometer in which the wavelength information is obtained by the use of strip or linear variable filters on the focal plane array. This kind of camera and spectrometer system can find applications in remote sensing, as well as in-situ applications for geological mapping and characterization of minerals, ecological studies, and target detection and identification through spectral signatures. Commercially, the lens can be used in quality-control applications via spectral analysis. The lens design is based on the rear landscape

  15. Capabilities and Facilities Available at the Advanced Test Reactor to Support Development of the Next Generation Reactors

    SciTech Connect

    S. Blaine Grover; Raymond V. Furstenau

    2005-10-01

    The ATR is one of the world’s premiere test reactors for performing long term, high flux, and/or large volume irradiation test programs. It is a very versatile facility with a wide variety of experimental test capabilities for providing the environment needed in an irradiation experiment. These different capabilities include passive sealed capsule experiments, instrumented and/or temperature-controlled experiments, and pressurized water loop experiment facilities. The Irradiation Test Vehicle (ITV) installed in 1999 enhanced these capabilities by providing a built in experiment monitoring and control system for instrumented and/or temperature controlled experiments. This built in control system significantly reduces the cost for an actively monitored/temperature controlled experiments by providing the thermocouple connections, temperature control system, and temperature control gas supply and exhaust systems already in place at the irradiation position. Although the ITV in-core hardware was removed from the ATR during the last core replacement completed in early 2005, it (or a similar facility) could be re-installed for an irradiation program when the need arises. The proposed Gas Test Loop currently being designed for installation in the ATR will provide additional capability for testing of not only gas reactor materials and fuels but will also include enhanced fast flux rates for testing of materials and fuels for other next generation reactors including preliminary testing for fast reactor fuels and materials. This paper discusses the different irradiation capabilities available and the cost benefit issues related to each capability.

  16. Switched Broadband Services For The Home

    NASA Astrophysics Data System (ADS)

    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.

  17. Broadband rotor noise analyses

    NASA Technical Reports Server (NTRS)

    George, A. R.; Chou, S. T.

    1984-01-01

    The various mechanisms which generate broadband noise on a range of rotors studied include load fluctuations due to inflow turbulence, due to turbulent boundary layers passing the blades' trailing edges, and due to tip vortex formation. Existing analyses are used and extensions to them are developed to make more accurate predictions of rotor noise spectra and to determine which mechanisms are important in which circumstances. Calculations based on the various prediction methods in existing experiments were compared. The present analyses are adequate to predict the spectra from a wide variety of experiments on fans, full scale and model scale helicopter rotors, wind turbines, and propellers to within about 5 to 10 dB. Better knowledge of the inflow turbulence improves the accuracy of the predictions. Results indicate that inflow turbulence noise depends strongly on ambient conditions and dominates at low frequencies. Trailing edge noise and tip vortex noise are important at higher frequencies if inflow turbulence is weak. Boundary layer trailing edge noise, important, for large sized rotors, increases slowly with angle of attack but not as rapidly as tip vortex noise.

  18. Heterogeneous broadband network

    NASA Astrophysics Data System (ADS)

    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.

  19. Broadband rotor noise analyses

    NASA Astrophysics Data System (ADS)

    George, A. R.; Chou, S. T.

    1984-04-01

    The various mechanisms which generate broadband noise on a range of rotors studied include load fluctuations due to inflow turbulence, due to turbulent boundary layers passing the blades' trailing edges, and due to tip vortex formation. Existing analyses are used and extensions to them are developed to make more accurate predictions of rotor noise spectra and to determine which mechanisms are important in which circumstances. Calculations based on the various prediction methods in existing experiments were compared. The present analyses are adequate to predict the spectra from a wide variety of experiments on fans, full scale and model scale helicopter rotors, wind turbines, and propellers to within about 5 to 10 dB. Better knowledge of the inflow turbulence improves the accuracy of the predictions. Results indicate that inflow turbulence noise depends strongly on ambient conditions and dominates at low frequencies. Trailing edge noise and tip vortex noise are important at higher frequencies if inflow turbulence is weak. Boundary layer trailing edge noise, important, for large sized rotors, increases slowly with angle of attack but not as rapidly as tip vortex noise.

  20. Model helicopter rotor low frequency broadband noise

    NASA Technical Reports Server (NTRS)

    Humbad, N. G.; Harris, W. L.

    1982-01-01

    The results of an experimental investigation of low frequency broadband noise (LFBN) radiated from model helicopter rotors are presented. The results up to tip Mach number of 0.50 suggest that the peak sound pressure level (SPL) of LFBN appears to follow tip Mach number to a fourth power law and rms velocity of turbulence to a second power law. The experimental results on the effect of tip speed and advance ratio on the peak SPL of LFBN can be explained on the basis of a simple scaling law. However, the experimental results on the effect of blade loading on the peak SPL of LFBN is still not clearly understood. A simple peak SPL scaling law for noise from a helicopter in forward flight encountering a sinusoidal gust is also developed. The trends predicted by the scaling law with the experimental results are found satisfactory for the cases of variation of the peak SPL of LFBN with tip speed and advance ratio.

  1. Ultra-broadband photonic internet

    NASA Astrophysics Data System (ADS)

    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.

  2. Broadband set-top box using MAP-CA processor

    NASA Astrophysics Data System (ADS)

    Bush, John E.; Lee, Woobin; Basoglu, Chris

    2001-12-01

    Advances in broadband access are expected to exert a profound impact in our everyday life. It will be the key to the digital convergence of communication, computer and consumer equipment. A common thread that facilitates this convergence comprises digital media and Internet. To address this market, Equator Technologies, Inc., is developing the Dolphin broadband set-top box reference platform using its MAP-CA Broadband Signal ProcessorT chip. The Dolphin reference platform is a universal media platform for display and presentation of digital contents on end-user entertainment systems. The objective of the Dolphin reference platform is to provide a complete set-top box system based on the MAP-CA processor. It includes all the necessary hardware and software components for the emerging broadcast and the broadband digital media market based on IP protocols. Such reference design requires a broadband Internet access and high-performance digital signal processing. By using the MAP-CA processor, the Dolphin reference platform is completely programmable, allowing various codecs to be implemented in software, such as MPEG-2, MPEG-4, H.263 and proprietary codecs. The software implementation also enables field upgrades to keep pace with evolving technology and industry demands.

  3. Broadband Transmission EPR Spectroscopy

    PubMed Central

    Hagen, Wilfred R.

    2013-01-01

    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 (bio)molecular 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. PMID:23555819

  4. Residential Broadband Access for Students at Walters State Community College

    ERIC Educational Resources Information Center

    Hurst, Mark A.

    2010-01-01

    The purpose of this study was to determine the availability of internet access for students attending Walters State Community College during the spring semester 2010. In particular, it is unknown to what degree broadband internet access is available in the counties that Walters State considers the service area of the college. The research was…

  5. Broadband Access for Students at East Tennessee State University

    ERIC Educational Resources Information Center

    Sawyer, Thomas Scott

    2013-01-01

    The purpose of this study was to determine the availability of Internet access for students attending East Tennessee State University during the fall semester 2013. It has been unknown to what degree broadband access is available in the East Tennessee State University service area that includes counties in East Tennessee, Southwest Virginia, and…

  6. Broadband cavity electromagnetically induced transparency

    SciTech Connect

    Wei Xiaogang; Wang Yanhua; Zhang Jiepeng; Zhu Yifu

    2011-10-15

    Cavity electromagnetically induced transparency (EIT) is created in a three-level atomic system confined in a cavity and coupled to a free-space control laser and is manifested as a narrow transmission peak of a probe laser coupled into the cavity mode and tuned to the two-photon Raman resonance with the control laser. Cavity EIT can be observed with a control laser detuned from the atomic transition frequency in a range limited by the vacuum Rabi splitting of two cavity-atom normal modes. This leads to the broadband cavity EIT obtained in the coupled-cavity-atom system with a free-space, broadband control laser. We report an experimental observation of broadband cavity EIT in cold Rb atoms with a frequency-modulated control laser and discuss its application in multichannel and multifrequency light memory.

  7. Broadband surface-wave transformation cloak.

    PubMed

    Xu, Su; Xu, Hongyi; Gao, Hanhong; Jiang, Yuyu; Yu, Faxin; Joannopoulos, John D; Soljačić, Marin; Chen, Hongsheng; Sun, Handong; Zhang, Baile

    2015-06-23

    Guiding surface electromagnetic waves around disorder without disturbing the wave amplitude or phase is in great demand for modern photonic and plasmonic devices, but is fundamentally difficult to realize because light momentum must be conserved in a scattering event. A partial realization has been achieved by exploiting topological electromagnetic surface states, but this approach is limited to narrow-band light transmission and subject to phase disturbances in the presence of disorder. Recent advances in transformation optics apply principles of general relativity to curve the space for light, allowing one to match the momentum and phase of light around any disorder as if that disorder were not there. This feature has been exploited in the development of invisibility cloaks. An ideal invisibility cloak, however, would require the phase velocity of light being guided around the cloaked object to exceed the vacuum speed of light--a feat potentially achievable only over an extremely narrow band. In this work, we theoretically and experimentally show that the bottlenecks encountered in previous studies can be overcome. We introduce a class of cloaks capable of remarkable broadband surface electromagnetic waves guidance around ultrasharp corners and bumps with no perceptible changes in amplitude and phase. These cloaks consist of specifically designed nonmagnetic metamaterials and achieve nearly ideal transmission efficiency over a broadband frequency range from 0(+) to 6 GHz. This work provides strong support for the application of transformation optics to plasmonic circuits and could pave the way toward high-performance, large-scale integrated photonic circuits. PMID:26056299

  8. Broadband surface-wave transformation cloak

    PubMed Central

    Xu, Su; Xu, Hongyi; Gao, Hanhong; Jiang, Yuyu; Yu, Faxin; Joannopoulos, John D.; Soljačić, Marin; Chen, Hongsheng; Sun, Handong; Zhang, Baile

    2015-01-01

    Guiding surface electromagnetic waves around disorder without disturbing the wave amplitude or phase is in great demand for modern photonic and plasmonic devices, but is fundamentally difficult to realize because light momentum must be conserved in a scattering event. A partial realization has been achieved by exploiting topological electromagnetic surface states, but this approach is limited to narrow-band light transmission and subject to phase disturbances in the presence of disorder. Recent advances in transformation optics apply principles of general relativity to curve the space for light, allowing one to match the momentum and phase of light around any disorder as if that disorder were not there. This feature has been exploited in the development of invisibility cloaks. An ideal invisibility cloak, however, would require the phase velocity of light being guided around the cloaked object to exceed the vacuum speed of light—a feat potentially achievable only over an extremely narrow band. In this work, we theoretically and experimentally show that the bottlenecks encountered in previous studies can be overcome. We introduce a class of cloaks capable of remarkable broadband surface electromagnetic waves guidance around ultrasharp corners and bumps with no perceptible changes in amplitude and phase. These cloaks consist of specifically designed nonmagnetic metamaterials and achieve nearly ideal transmission efficiency over a broadband frequency range from 0+ to 6 GHz. This work provides strong support for the application of transformation optics to plasmonic circuits and could pave the way toward high-performance, large-scale integrated photonic circuits. PMID:26056299

  9. NAT Usage in Residential Broadband Networks

    NASA Astrophysics Data System (ADS)

    Maier, Gregor; Schneider, Fabian; Feldmann, Anja

    Many Internet customers use network address translation (NAT) when connecting to the Internet. To understand the extend of NAT usage and its implications, we explore NAT usage in residential broadband networks based on observations from more than 20,000 DSL lines. We present a unique approach for detecting the presence of NAT and for estimating the number of hosts connected behind a NAT gateway using IP TTLs and HTTP user-agent strings. Furthermore, we study when each of the multiple hosts behind a single NAT gateway is active. This enables us to detect simultaneous use. In addition, we evaluate the accuracy of NAT analysis techniques when fewer information is available.

  10. Integrated-Circuit Broadband Infrared Sources

    NASA Technical Reports Server (NTRS)

    Lamb, G.; Jhabvala, M.; Burgess, A.

    1989-01-01

    Microscopic devices consume less power, run hotter, and are more reliable. Simple, compact, lightweight, rapidly-responding reference sources of broadband infrared radiation made available by integrated-circuit technology. Intended primarily for use in calibration of remote-sensing infrared instruments, devices eventually replace conventional infrared sources. New devices also replace present generation of miniature infrared sources. Self-passivating nature of poly-crystalline silicon adds to reliability of devices. Maximum operating temperature is 1,000 K, and power dissipation is only one-fourth that of prior devices.

  11. [Not Available].

    PubMed

    Zecchini, Céline; Chanoine, Sébastien; Chapuis, Claire; Claustre, Johanna; Schir, Edith; Allenet, Benoît; Raymond, Christel Saint; Bedouch, Pierrick

    2015-01-01

    Advances in lung transplantation allow the women of childbearing age to consider becoming mothers. When planning to become pregnant, a therapeutic drug management of immunosuppressive drugs and associated therapies is required. It must take into account teratogenic and fetotoxic drugs, as well as pharmacokinetic changes encountered during pregnancy. Increasingly data are currently available on the management of immunosuppressive drugs and associated therapies during pregnancy. We report the case management of drug therapy before and during pregnancy in two patients after a lung or heart-lung transplantation. To prevent the emergence of complications for mother and child, a literature review has been necessary to manage drug therapies of each patient. PMID:27393315

  12. Exploring Geographic Disparities in Broadband Access and Use in Rural Southern Illinois: Who's Being Left behind?

    ERIC Educational Resources Information Center

    Oyana, Tonny J.

    2011-01-01

    Recent literature about broadband telecommunications reveals two major areas that are not only globally gaining prominence, but are also demanding urgent attention from a research perspective. One of the key areas is related to the need to spatially evaluate the availability and deployment of broadband services, especially among urban versus rural…

  13. DKIST visible broadband imager interference filters

    NASA Astrophysics Data System (ADS)

    Wöger, Friedrich

    2014-08-01

    The Visible Broadband Imager (VBI) is one of several first-light instruments of the Daniel K. Inouye Solar Telescope (DKIST, formerly known as the Advanced Technology Solar Telescope (ATST)). Operating at discrete wavelengths within a range of 390-860 nm, the VBI will be capable of sampling the solar atmosphere in several layers at the diffraction limit of DKIST's 4 meter aperture. The layers are selected by the peak wavelength and bandpass width of its interference filters that have to be manufactured to very tight specifications. We present the results of testing performed at the National Solar Observatory's Dunn Solar Telescope (DST) to confirm that the requirements were met by the vendor.

  14. Let there be light and broadband internet: You will have a happier life, I bet.

    NASA Astrophysics Data System (ADS)

    Kavehrad, Mohsen

    2007-09-01

    Home users are in need for broadband communications access, globally. Broadband over power-lines transmission has advanced throughout the last decade, and it is going to be a mature last-mile access in near future. Meanwhile, indoor optical wireless communications (optical WiFi) through lighting LEDs has been investigated, recently. It is shown that a combination of these two techniques provides an efficient way of fulfilling the premise of broadband access for home networking, while providing efficient and low-cost lighting.

  15. Networked Nation: Broadband in America, 2007

    ERIC Educational Resources Information Center

    National Telecommunications and Information Administration, 2008

    2008-01-01

    This report highlights the dramatic growth of broadband in the United States. The report shows that the Administration's technology, regulatory and fiscal policies have stimulated innovation and competition, and encouraged investment in the U.S. broadband market contributing to significantly increased accessibility of broadband services. The…

  16. Broadband/Wideband Magnetoelectric Response

    DOE PAGESBeta

    Park, Chee-Sung; Priya, Shashank

    2012-01-01

    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 andmore » 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.« less

  17. Retinal imaging using commercial broadband optical coherence tomography

    PubMed Central

    Tanna, Hitesh; Dubis, Adam M; Ayub, Nazia; Tait, Diane M; Rha, Jungtae; Stepien, Kimberly E; Carroll, Joseph

    2012-01-01

    Aims To examine the practical improvement in image quality afforded by a broadband light source in a clinical setting and to define image quality metrics for future use in evaluating spectral domain optical coherence tomography (SD-OCT) images. Methods A commercially available SD-OCT system, configured with a standard source as well as an external broadband light source, was used to acquire 4 mm horizontal line scans of the right eye of 10 normal subjects. Scans were averaged to reduce speckling and multiple retinal layers were analysed in the resulting images. Results For all layers there was a significant improvement in the mean local contrast (average improvement by a factor of 1.66) when using the broadband light source. Intersession variability was shown not to be a major contributing factor to the observed improvement in image quality obtained with the broadband light source. We report the first observation of sublamination within the inner plexiform layer visible with SD-OCT. Conclusion The practical improvement with the broadband light source was significant, although it remains to be seen what the utility will be for diagnostic pathology. The approach presented here serves as a model for a more quantitative analysis of SD-OCT images, allowing for more meaningful comparisons between subjects, clinics and SD-OCT systems. PMID:19770161

  18. Broadband Trailing Edge Noise Predictions in the Time Domain. Revised

    NASA Technical Reports Server (NTRS)

    Casper, Jay; Farassat, Fereidoun

    2003-01-01

    A recently developed analytic result in acoustics, "Formulation 1B," is used to compute broadband trailing edge noise from an unsteady surface pressure distribution on a thin airfoil in the time domain. This formulation is a new solution of the Ffowcs Willliams-Hawkings equation with the loading source term, and has been shown in previous research to provide time domain predictions of broadband noise that are in excellent agreement with experimental results. Furthermore, this formulation lends itself readily to rotating reference frames and statistical analysis of broadband trailing edge noise. Formulation 1B is used to calculate the far field noise radiated from the trailing edge of a NACA 0012 airfoil in low Mach number flows, by using both analytical and experimental data on the airfoil surface. The acoustic predictions are compared with analytical results and experimental measurements that are available in the literature. Good agreement between predictions and measurements is obtained.

  19. Broadband trailing edge noise predictions in the time domain

    NASA Astrophysics Data System (ADS)

    Casper, J.; Farassat, F.

    2004-03-01

    A recently developed analytic result in acoustics, "Formulation 1B," is used to compute broadband trailing edge noise from an unsteady surface pressure distribution on a thin airfoil in the time domain. This formulation is a new solution of the Ffowcs Williams-Hawkings equation with the loading source term, and has been shown in previous research to provide time domain predictions of broadband noise that are in excellent agreement with experimental results. Furthermore, this formulation lends itself readily to rotating reference frames and statistical analysis of broadband trailing edge noise. In the present work, Formulation 1B is used to calculate the farfield noise radiated from the trailing edge of a NACA 0012 airfoil in a low Mach number flow, using both analytical and experimental data on the airfoil surface. The acoustic predictions are compared with analytical results and experimental measurements that are available in the literature. Good agreement between predictions and measurements is obtained.

  20. A Blueprint for Big Broadband. An EDUCAUSE White Paper

    ERIC Educational Resources Information Center

    Windhausen, John, Jr.

    2008-01-01

    This white paper proposes bringing the federal government, state governments, and the private sector together as part of a new approach to making high-speed Internet services available across the country. It proposes the creation of a new federal Universal Broadband Fund (UBF) that, together with matching funds from the states and the private…

  1. Broadband Behavior Rating Scales as Screeners for Autism?

    ERIC Educational Resources Information Center

    Myers, Carl L.; Gross, Amber D.; McReynolds, Brandy M.

    2014-01-01

    In order to start providing important early intervention services to preschoolers and toddlers with autism, those children first need to be identified. Despite the availability of specialized autism assessment instruments, there is a need for effective screeners at the early childhood level. Three broadband behavior rating scales were evaluated in…

  2. Visible light broadband perfect absorbers

    NASA Astrophysics Data System (ADS)

    Jia, X. L.; Meng, Q. X.; Yuan, C. X.; Zhou, Z. X.; Wang, X. O.

    2016-03-01

    The visible light broadband perfect absorbers based on the silver (Ag) nano elliptical disks and holes array are studied using finite difference time domain simulations. The semiconducting indium silicon dioxide thin film is introduced as the space layer in this sandwiched structure. Utilizing the asymmetrical geometry of the structures, polarization sensitivity for transverse electric wave (TE)/transverse magnetic wave (TM) and left circular polarization wave (LCP)/right circular polarization wave (RCP) of the broadband absorption are gained. The absorbers with Ag nano disks and holes array show several peaks absorbance of 100% by numerical simulation. These simple and flexible perfect absorbers are particularly desirable for various potential applications including the solar energy absorber.

  3. Integrated Broadband Quantum Cascade Laser

    NASA Technical Reports Server (NTRS)

    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.

  4. Broadband light-emitting diode

    DOEpatents

    Fritz, I.J.; Klem, J.F.; Hafich, M.J.

    1998-07-14

    A broadband light-emitting diode is disclosed. The broadband light-emitting diode (LED) comprises a plurality of III-V compound semiconductor layers grown on a semiconductor substrate, with the semiconductor layers including a pair of cladding layers sandwiched about a strained-quantum-well active region having a plurality of different energy bandgaps for generating light in a wavelength range of about 1.3--2 {micro}m. In one embodiment of the present invention, the active region may comprise a first-grown quantum-well layer and a last-grown quantum-well layer that are oppositely strained; whereas in another embodiment of the invention, the active region is formed from a short-period superlattice structure (i.e. a pseudo alloy) comprising alternating thin layers of InGaAs and InGaAlAs. The use a short-period superlattice structure for the active region allows different layers within the active region to be simply and accurately grown by repetitively opening and closing one or more shutters in an MBE growth apparatus to repetitively switch between different growth states therein. The broadband LED may be formed as either a surface-emitting LED or as an edge-emitting LED for use in applications such as chemical sensing, fiber optic gyroscopes, wavelength-divisionmultiplexed (WDM) fiber-optic data links, and WDM fiber-optic sensor networks for automobiles and aircraft. 10 figs.

  5. Broadband light-emitting diode

    DOEpatents

    Fritz, Ian J.; Klem, John F.; Hafich, Michael J.

    1998-01-01

    A broadband light-emitting diode. The broadband light-emitting diode (LED) comprises a plurality of III-V compound semiconductor layers grown on a semiconductor substrate, with the semiconductor layers including a pair of cladding layers sandwiched about a strained-quantum-well active region having a plurality of different energy bandgaps for generating light in a wavelength range of about 1.3-2 .mu.m. In one embodiment of the present invention, the active region may comprise a first-grown quantum-well layer and a last-grown quantum-well layer that are oppositely strained; whereas in another embodiment of the invention, the active region is formed from a short-period superlattice structure (i.e. a pseudo alloy) comprising alternating thin layers of InGaAs and InGaAlAs. The use a short-period superlattice structure for the active region allows different layers within the active region to be simply and accurately grown by repetitively opening and closing one or more shutters in an MBE growth apparatus to repetitively switch between different growth states therein. The broadband LED may be formed as either a surface-emitting LED or as an edge-emitting LED for use in applications such as chemical sensing, fiber optic gyroscopes, wavelength-division-multiplexed (WDM) fiber-optic data links, and WDM fiber-optic sensor networks for automobiles and aircraft.

  6. Broad-band beam buncher

    DOEpatents

    Goldberg, David A.; Flood, William S.; Arthur, Allan A.; Voelker, Ferdinand

    1986-01-01

    A broad-band beam buncher is disclosed, comprising an evacuated housing, an electron gun therein for producing an electron beam, a buncher cavity having entrance and exit openings through which the beam is directed, grids across such openings, a source providing a positive DC voltage between the cavity and the electron gun, a drift tube through which the electron beam travels in passing through such cavity, grids across the ends of such drift tube, gaps being provided between the drift tube grids and the entrance and exit grids, a modulator for supplying an ultrahigh frequency modulating signal to the drift tube for producing velocity modulation of the electrons in the beam, a drift space in the housing through which the velocity modulated electron beam travels and in which the beam is bunched, and a discharge opening from such drift tube and having a grid across such opening through which the bunched electron beam is discharged into an accelerator or the like. The buncher cavity and the drift tube may be arranged to constitute an extension of a coaxial transmission line which is employed to deliver the modulating signal from a signal source. The extended transmission line may be terminated in its characteristic impedance to afford a broad-band response and the device as a whole designed to effect broad-band beam coupling, so as to minimize variations of the output across the response band.

  7. A study of rotor broadband noise mechanisms and helicopter tail rotor noise

    NASA Technical Reports Server (NTRS)

    Chou, Shau-Tak Rudy

    1990-01-01

    The rotor broadband noise mechanisms considered are the following: (1) lift fluctuation due to turbulence ingestion; (2) boundary layer/trailing edge interaction; (3) tip vortex formation; and (4) turbulent vortex shedding from blunt trailing edge. Predictions show good agreement with available experimental data. The study shows that inflow turbulence is the most important broadband noise source for typical helicopters' main rotors at low- and mid-frequencies. Due to the size difference, isolated helicopter tail rotor broadband noise is not important compared to the much louder main rotor broadband noise. However, the inflow turbulence noise from a tail rotor can be very significant because it is operating in a highly turbulent environment, ingesting wakes from upstream components of the helicopter. The study indicates that the main rotor turbulent wake is the most important source of tail rotor broadband noise. The harmonic noise due to ingestion of main rotor tip vortices is studied.

  8. Can currently available advanced combustion biomass cook-stoves provide health relevant exposure reductions? Results from initial assessment of select commercial models in India.

    PubMed

    Sambandam, Sankar; Balakrishnan, Kalpana; Ghosh, Santu; Sadasivam, Arulselvan; Madhav, Satish; Ramasamy, Rengaraj; Samanta, Maitreya; Mukhopadhyay, Krishnendu; Rehman, Hafeez; Ramanathan, Veerabhadran

    2015-03-01

    Household air pollution from use of solid fuels is a major contributor to the national burden of disease in India. Currently available models of advanced combustion biomass cook-stoves (ACS) report significantly higher efficiencies and lower emissions in the laboratory when compared to traditional cook-stoves, but relatively little is known about household level exposure reductions, achieved under routine conditions of use. We report results from initial field assessments of six commercial ACS models from the states of Tamil Nadu and Uttar Pradesh in India. We monitored 72 households (divided into six arms to each receive an ACS model) for 24-h kitchen area concentrations of PM2.5 and CO before and (1-6 months) after installation of the new stove together with detailed information on fixed and time-varying household characteristics. Detailed surveys collected information on user perceptions regarding acceptability for routine use. While the median percent reductions in 24-h PM2.5 and CO concentrations ranged from 2 to 71% and 10-66%, respectively, concentrations consistently exceeded WHO air quality guideline values across all models raising questions regarding the health relevance of such reductions. Most models were perceived to be sub-optimally designed for routine use often resulting in inappropriate and inadequate levels of use. Household concentration reductions also run the risk of being compromised by high ambient backgrounds from community level solid-fuel use and contributions from surrounding fossil fuel sources. Results indicate that achieving health relevant exposure reductions in solid-fuel using households will require integration of emissions reductions with ease of use and adoption at community scale, in cook-stove technologies. Imminent efforts are also needed to accelerate the progress towards cleaner fuels. PMID:25293811

  9. POTS to broadband ... cable modems.

    PubMed

    Kabachinski, Jeff

    2003-01-01

    There have been 3 columns talking about broadband communications and now at the very end when it's time to compare using a telco or cableco, I'm asking does it really matter? So what if I can actually get the whole 30 Mbps with a cable network when the website I'm connecting to is running on an ISDN line at 128 Kbps? Broadband offers a lot more bandwidth than the connections many Internet servers have today. Except for the biggest websites, many servers connect to the Internet with a switched 56-Kbps, ISDN, or fractional T1 line. Even with the big websites, my home network only runs a 10 Mbps Ethernet connection to my cable modem. Maybe it doesn't matter that the cable lines are shared or that I can only get 8 Mbps from an ADSL line. Maybe the ISP that I use has a T1 line connection to the Internet so my new ADSL modem has a fatter pipe than my provider! (See table 1). It all makes me wonder what's in store for us in the future. PC technology has increased exponentially in the last 10 years with super fast processor speeds, hard disks of hundreds of gigabytes, and amazing video and audio. Internet connection speeds have failed to keep the same pace. Instead of hundreds of times better or faster--modem speeds are barely 10 times faster. Broadband connections offer some additional speed but still not comparable growth as broadband connections are still in their infancy. Rather than trying to make use of existing communication paths, maybe we need a massive infrastructure makeover of something new. How about national wireless access points so we can connect anywhere, anytime? To use the latest and fastest wireless technology you will simply need to buy another $9.95 WLAN card or download the latest super slick WLAN compression/encryption software. Perhaps it is time for a massive infra-restructuring. Consider the past massive infrastructure efforts. The telcos needed to put in their wiring infrastructure starting in the 1870s before telephones were useful to the

  10. Broadband tuning of optomechanical cavities

    NASA Astrophysics Data System (ADS)

    Wiederhecker, Gustavo S.; Manipatruni, Sasikanth; Lee, Sunwoo; Lipson, Michal

    2011-01-01

    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. Mammoth Mountain, California broadband seismic experiment

    NASA Astrophysics Data System (ADS)

    Dawson, P. B.; Pitt, A. M.; Wilkinson, S. K.; Chouet, B. A.; Hill, D. P.; Mangan, M.; Prejean, S. G.; Read, C.; Shelly, D. R.

    2013-12-01

    Mammoth Mountain is a young cumulo-volcano located on the southwest rim of Long Valley caldera, California. Current volcanic processes beneath Mammoth Mountain are manifested in a wide range of seismic signals, including swarms of shallow volcano-tectonic earthquakes, upper and mid-crustal long-period earthquakes, swarms of brittle-failure earthquakes in the lower crust, and shallow (3-km depth) very-long-period earthquakes. Diffuse emissions of C02 began after a magmatic dike injection beneath the volcano in 1989, and continue to present time. These indications of volcanic unrest drive an extensive monitoring effort of the volcano by the USGS Volcano Hazards Program. As part of this effort, eleven broadband seismometers were deployed on Mammoth Mountain in November 2011. This temporary deployment is expected to run through the fall of 2013. These stations supplement the local short-period and broadband seismic stations of the Northern California Seismic Network (NCSN) and provide a combined network of eighteen broadband stations operating within 4 km of the summit of Mammoth Mountain. Data from the temporary stations are not available in real-time, requiring the merging of the data from the temporary and permanent networks, timing of phases, and relocation of seismic events to be accomplished outside of the standard NCSN processing scheme. The timing of phases is accomplished through an interactive Java-based phase-picking routine, and the relocation of seismicity is achieved using the probabilistic non-linear software package NonLinLoc, distributed under the GNU General Public License by Alomax Scientific. Several swarms of shallow volcano-tectonic earthquakes, spasmodic bursts of high-frequency earthquakes, a few long-period events located within or below the edifice of Mammoth Mountain and numerous mid-crustal long-period events have been recorded by the network. To date, about 900 of the ~2400 events occurring beneath Mammoth Mountain since November 2011 have

  12. Open rotor broadband interaction noise

    NASA Astrophysics Data System (ADS)

    Kingan, Michael J.

    2013-08-01

    A theoretical model is presented for calculating the broadband noise produced by the interaction of an open rotor with the wake from either an upstream contra-rotating rotor or a stationary pylon. The model is used to investigate the dependence of the radiated noise on parameters such as pylon-rotor gap and the polar and azimuthal directivity of the noise field. A simple model is also presented which assumes that the unsteady loading on adjacent blades is uncorrelated. It is shown that the simple model can be used to calculate broadband interaction noise for most practical open rotor geometries. The errors in Ref. [3] are listed in this footnote. (1) The effect of wake skew on the 'mean wake profile' was not properly accounted for (see Eqs. (38 and 39) of this paper). (2) The final formulation contained an extra factor of 2π due to an inconsistent Fourier transform convention. (3) There was an error in the wavenumber contained in the blade response function g (see Appendix 1 of this paper). (4) There were a number of errors in the 'acoustically weighted lift function', ΨL, which is defined in Appendix 1 of this paper.

  13. Broadband light based optoelectric tweezers

    NASA Astrophysics Data System (ADS)

    Mishra, Avanish; Clayton, Katherine; Wereley, Steve

    2015-11-01

    Trapping, sorting and transport of particles are fundamental operations in microfluidic platforms. However, very few methods exist that can dynamically trap and manipulate particles with high spatial resolution and accuracy. Recently, a new set of methods have emerged that can trap and sort particles by optically controlling electrokinetic effects. Rapid Electrokinetic Patterning (REP) is such an emerging optoelectric technique. It utilizes a laser activated electrothermal (ET) vortex and particle-electrode interactions for trapping particles. Trapped particles can be translated by optically steering the laser or by moving the trapping chamber. Previously demonstrated applications of REP have utilized a 1064 nm infrared laser, integrated in an inverted microscope, to create the necessary temperature rise for producing the ET flow. Use of an external laser for REP trapping is expensive and time intensive to integrate, making it difficult to design a portable REP system. Using experiments and simulations, we show that a non-coherent incandescent broadband light source can be used for REP trapping and manipulation. This allows for a microscope with a broadband lamp to be used for REP trapping without integrating an external laser.

  14. Faster, Faster! Broadband Access to the Internet.

    ERIC Educational Resources Information Center

    Sheehan, Mark

    1999-01-01

    Defines "plain old telephone service" (POTS) and broadband communication, comparing costs and performance of cable modems with POTS modems. Describes Integrated Services Digital Network (ISDN) and digital subscriber line (DSL) services. Discusses broadband wireless and satellite networks. Three sidebars illustrate differences between…

  15. Big Broadband Connectivity in the United States

    ERIC Educational Resources Information Center

    Windhausen, John, Jr.

    2008-01-01

    The economic and social future of the United States depends on answering the growing demand for very high-speed broadband connectivity, a capability termed "big broadband." Failure to take on the challenge could lead to a decline in global competitiveness and an inability to educate students. (Contains 20 notes.)

  16. Broadband Helps Bridge the Achievement Gap

    ERIC Educational Resources Information Center

    Simmons, Jamal

    2013-01-01

    In education, technology is giving new meaning to the phrase "equal opportunity." Teachers and students in schools across America--urban, rural, wealthy, and impoverished--are gaining access to online learning and all of its benefits through broadband technology. What is broadband? According to the Federal Communications Commission (FCC), it is…

  17. 75 FR 25185 - Broadband Initiatives Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-07

    ...The Rural Utilities Service (RUS) announced its general policy and application procedures for the second round of funding under the broadband initiatives (the Second Round NOFA), established pursuant to the American Recovery and Reinvestment Act of 2009 (Recovery Act) for the Broadband Initiatives Program (BIP), on January 22, 2010 at 74 FR 3820. In that Second Round NOFA, RUS announced the......

  18. Customer Churn Prediction for Broadband Internet Services

    NASA Astrophysics Data System (ADS)

    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.

  19. Swift/BAT and MAXI/GSC broadband transient monitor

    NASA Astrophysics Data System (ADS)

    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.

  20. Swift/BAT and MAXI/GSC broadband transient monitor

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

    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.

  1. Broadband synthetic aperture geoacoustic inversion.

    PubMed

    Tan, Bien Aik; Gerstoft, Peter; Yardim, Caglar; Hodgkiss, William S

    2013-07-01

    A typical geoacoustic inversion procedure involves powerful source transmissions received on a large-aperture receiver array. A more practical approach is to use a single moving source and/or receiver in a low signal to noise ratio (SNR) setting. This paper uses single-receiver, broadband, frequency coherent matched-field inversion and exploits coherently repeated transmissions to improve estimation of the geoacoustic parameters. The long observation time creates a synthetic aperture due to relative source-receiver motion. This approach is illustrated by studying the transmission of multiple linear frequency modulated (LFM) pulses which results in a multi-tonal comb spectrum that is Doppler sensitive. To correlate well with the measured field across a receiver trajectory and to incorporate transmission from a source trajectory, waveguide Doppler and normal mode theory is applied. The method is demonstrated with low SNR, 100-900 Hz LFM pulse data from the Shallow Water 2006 experiment. PMID:23862809

  2. ESTIMATION OF LAND SURFACE BROADBAND ALBEDOS AND LEAF AREA INDEX FROM EO-1 DATA AND VALIDATION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Advanced Land Imager (ALI) is a multispectral sensor onboard NASA Earth Observer-1 (EO-1). It has similar spatial resolution to the Landsat-7 Enhanced Thematic Mapper Plus (ETM+), with three additional spectral bands. We developed new algorithms for estimating both land surface broadband albedo...

  3. Unleashing Waves of Innovation: Transformative Broadband for America's Future. Version 18

    ERIC Educational Resources Information Center

    Western Interstate Commission for Higher Education, 2009

    2009-01-01

    A forward-thinking National Broadband Strategy should focus on the transformative power of advanced networks to unleash new waves of innovation, jobs, economic growth, and national competitiveness. Such a strategy should create new tools to deliver health care, education, and a low carbon economy. The American Recovery and Reinvestment Act…

  4. Global Optimization and Broadband Analysis Software for Interstellar Chemistry (GOBASIC)

    NASA Astrophysics Data System (ADS)

    Rad, Mary L.; Zou, Luyao; Sanders, James L.; Widicus Weaver, Susanna L.

    2016-01-01

    Context. Broadband receivers that operate at millimeter and submillimeter frequencies necessitate the development of new tools for spectral analysis and interpretation. Simultaneous, global, multimolecule, multicomponent analysis is necessary to accurately determine the physical and chemical conditions from line-rich spectra that arise from sources like hot cores. Aims: We aim to provide a robust and efficient automated analysis program to meet the challenges presented with the large spectral datasets produced by radio telescopes. Methods: We have written a program in the MATLAB numerical computing environment for simultaneous global analysis of broadband line surveys. The Global Optimization and Broadband Analysis Software for Interstellar Chemistry (GOBASIC) program uses the simplifying assumption of local thermodynamic equilibrium (LTE) for spectral analysis to determine molecular column density, temperature, and velocity information. Results: GOBASIC achieves simultaneous, multimolecule, multicomponent fitting for broadband spectra. The number of components that can be analyzed at once is only limited by the available computational resources. Analysis of subsequent sets of molecules or components is performed iteratively while taking the previous fits into account. All features of a given molecule across the entire window are fitted at once, which is preferable to the rotation diagram approach because global analysis is less sensitive to blended features and noise features in the spectra. In addition, the fitting method used in GOBASIC is insensitive to the initial conditions chosen, the fitting is automated, and fitting can be performed in a parallel computing environment. These features make GOBASIC a valuable improvement over previously available LTE analysis methods. A copy of the sofware is available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/585/A23

  5. Broadband monopole optical nano-antennas

    NASA Astrophysics Data System (ADS)

    Zhou, Rongguo; Ding, Jun; Arigong, Bayaner; Lin, Yuankun; Zhang, Hualiang

    2014-03-01

    In this paper, a novel design of broadband monopole optical nano-antennas is proposed. It consists of a corrugated halfelliptical patch inside an elliptical aperture. Full-wave electromagnetic simulations have been used to investigate the performance of the nano-antenna. The predicted performance of the proposed monopole nano-antenna is remarkably broadband. Moreover, the proposed broadband nano-antenna can respond to light waves with different polarizations. The proposed optical antenna will pave the way towards the development of high performance optical antennas and optical systems.

  6. Broadband local service offerings using free-space optical links: a network business perspective

    NASA Astrophysics Data System (ADS)

    Britz, David M.; Dodley, J. P.; Barnickel, D. J.

    2001-02-01

    12 This paper describes a promising optical wireless broadband technology that will provide low cost broadband services to the local access `last mile' market. This paper examines the application, advantages and limitations of utilizing Free Space Optical Communications (FSOC) systems for broadband access markets. The service markets that would fully utilize FSOC technologies include metropolitan areas, BLECs (multi- tenant dwellings/business apartments), campuses, industrial parks and `pole-to-hole' neighborhood deployments. This paper will identify weather dependent link availability as being the primary consideration in defining and selecting suitable locations for FSOC-based systems. Link availability in turn determines link range, type of service, and the need for transmission diversity. This paper will describe the implications of telecom `five nines' last-mile access availability and its effect on the transparent integration of FSOC technologies into the existing fiber optic networks. This paper will also describe propagation losses and link budget requirements for broadband FSOC-based local service. During adverse weather conditions, stand-alone, FSOC-based optical wireless links typically offer path lengths of less than 200 meters while still meeting the `five nines' availability criteria. This paper will also consider `availability limited' services. These services may prove to be attractive to customers who are willing to accept broadband service on an `as available basis'. The use of availability-enhancing transmission diversity and the use of intelligent `roof-top' routing and optical wireless cross connects between buildings will also be discussed.

  7. Swift/BAT and MAXI/GSC broadband transient monitor

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    "Time-domain astronomy" is one of the frontier field of astronomy for the next decade. Since the most of the transient sources show the temporal variation in a broad spectral range, it would be ideal to have the real time transient monitor which covers a wide energy band. 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 (15-200keV) and the GSC (2-20keV) data. Currently, daily and 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 wider use by the community. We discuss the daily sensitivity of our monitor and possible future improvements to our pipeline.

  8. 47 CFR 90.1405 - Shared wireless broadband network.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 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....

  9. 47 CFR 27.1305 - Shared wireless broadband network.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Shared wireless broadband network. 27.1305... 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....

  10. 47 CFR 27.1305 - Shared wireless broadband network.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Shared wireless broadband network. 27.1305... 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....

  11. 47 CFR 90.1405 - Shared wireless broadband network.

    Code of Federal Regulations, 2010 CFR

    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....

  12. Broadband circular polarizers constructed using helix-like chiral metamaterials

    NASA Astrophysics Data System (ADS)

    Ji, Ruonan; Wang, Shao-Wei; Liu, Xingxing; Chen, Xiaoshuang; Lu, Wei

    2016-08-01

    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. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01738j

  13. Nanophotonic Design for Broadband Light Management

    SciTech Connect

    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.

  14. 75 FR 10464 - Broadband Technology Opportunities Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-08

    ... National Telecommunications and Information Administration RIN 0660-ZA28 Broadband Technology Opportunities Program AGENCY: National Telecommunications and Information Administration, U.S. Department of Commerce... Register announcing general policy and application procedures for the second round of BTOP funding. 75...

  15. The Future of the Very Broadband Seismic Sensor

    NASA Astrophysics Data System (ADS)

    Ingate, S. F.; Berger, J.; Collins, J.; Farrell, W.; Fowler, J.; Herrington, P.; Hutt, C. R.; Romanowicz, B.; Sacks, S.; Vernon, F.; Wielandt, E.

    2004-05-01

    Few fundamental advances have been made in seismometers since the introduction of the broadband feedback systems nearly 1/4 century ago. In the intervening period, academic (and to a lesser extent industrial) research and developments on seismographic instrumentation has declined. Today, adequate sensors to meet the scientific requirements are in short supply. This is particularly true of the GSN; the cornerstone of GSN instrumentation is the STS-1 seismometer, which is no longer in production. Further, the pool of trained scientists working on seismographic instrumentation has dwindled to near zero. A 2.5 day workshop was held in Tahoe in March, 2004. Over 40 participants from government, universities, and corporate sectors participated in a mixture of oral, poster and discussion sessions. Through this workshop, the geoscience community interacted with research and development groups involved in sensor technology, material sciences and nanotechnology to assess emerging technologies that have applications in inertial sensors. A goal of this workshop was to consider whether and how such advances might be applied to the design and manufacture of a new-generation, ultra-quiet, mHz - 20 Hz seismic sensors. Key items included an examination of partnerships and technology transfer, new and innovative designs, testing standards and testing facilities, funding strategies and an educational perspective including new University programs. One product of this workshop is the formulation of a plan to revitalize research and development of techniques in broadband seismometry and related seismographic instrumentation.

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

    NASA Technical Reports Server (NTRS)

    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.

  17. Broadband Microwave Amplifier Design with Lumped Elements

    NASA Astrophysics Data System (ADS)

    Şengül, Metin

    2016-03-01

    This study introduces a broadband microwave amplifier design that utilizes the measured scattering parameters of active devices without assuming an initial topology for the matching networks or an analytic form of the system transfer function. The algorithm can be extended to design multistage broadband microwave amplifiers. An example is given to illustrate the application of the proposed method. It was found that the proposed method provides very good initials for CAD tools to further improve amplifier performance by working on the element values.

  18. Multi-Mode Broadband Patch Antenna

    NASA Technical Reports Server (NTRS)

    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.

  19. Broad-band beam buncher

    DOEpatents

    Goldberg, D.A.; Flood, W.S.; Arthur, A.A.; Voelker, F.

    1984-03-20

    A broad-band beam bunther is disclosed, comprising an evacuated housing, an electron gun therein for producing an electron beam, a buncher cavity having entrance and exit openings through which the beam is directed, grids across such openings, a source providing a positive DC voltage between the cavity and the electron gun, a drift tube through which the electron beam travels in passing through such cavity, grids across the ends of such drift tube, gaps being provided between the drift tube grids and the entrance and exit grids, a modulator for supplying an ultrahigh frequency modulating signal to the drift tube for producing velocity modulation of the electrons in the beam, a drift space in the housing through which the velocity modulated electron beam travels and in which the beam is bunched, and a discharge opening from such drift tube and having a grid across such opening through which the bunched electron beam is discharged into an accelerator or the like. The buncher cavity and the drift tube may be arranged to constitute an extension of a coaxial transmission line which is employed to deliver the modulating signal from a signal source. The extended transmission line may be terminated in its characteristic impedance to afford a broad-

  20. [Not Available].

    PubMed

    Gellerfors, Mikael; Gryth, Dan; Lossius, Hans Morten; Linde, Joacim

    2016-01-01

    For the most severely injured and unstable patients physician staffed second tier emergency medical service (EMS) units are used in many European areas. Physician staffed prehospital care is associated with a high rate of survival, advanced trauma care and beneficial cost-effectiveness. In the Nordic countries anaesthesiologists staff the rapid response cars and ambulance helicopters. This article reviews the current status of physician EMS in Sweden and the rapid development of new prehospital intensive care methods. PMID:27003522

  1. High-speed broadband tunable lasers

    NASA Astrophysics Data System (ADS)

    Adams, Laura E.; Nykolak, Gerald; Bethea, Clyde G.; Tanbun-Ek, Tawee; People, Roosevelt; Sergent, A. M.; Sciortino, Paul F., Jr.; Fullowan, Thomas R.

    1997-12-01

    New enabling technologies are needed for optical communication systems to accommodate rapidly growing traffic demands. Wavelength conversion and high-speed optical packet switching/routing will be key technology components for realizing more flexible and efficient optical networks. Lasers capable of wide-band, high-speed wavelength tuning will be essential to support these advanced functions. Also, many applications will require high launch powers in order to access an increasing number of users, nodes, or base stations. Hence, laser transmitters capable of suppressing stimulated Brillouin scattering (SBS) would be highly desirable. We have developed an ultrafast, broadband tunable laser, based on an electroabsorption modulator laser (EML), which exhibits wavelength switching speeds as fast as 56 ps. Here, we report system performance results on wavelength conversion high-speed optical packet switching, and SBS suppression using this device. We have tested multiple wavelength conversion sequences and demonstrated penalty-free transmission through two cascaded wavelength conversion stages including 200 km of standard non-DS fiber. When used to perform packet switching at 2.5 Gb/s, the tunable laser allows switching between optical packets on 4 wavelength channels in less than 1 bit period, thereby requiring no significant guardband. The modulated data packets have been transmitted through 200 km of non-DSF and yield open eye diagrams. The tunable laser has also been used to perform SBS suppression. We have measured SBS thresholds of approximately 25 dBm on 4 separate WDM channels. The required modulation signal is very small, 95 mVpp, and the residual AM is only approximately 1%.

  2. Perceived Availability and Risk of Harm of Drugs: Estimates from the National Household Survey on Drug Abuse. Advance Report Number 5.

    ERIC Educational Resources Information Center

    Gfroerer, Joseph

    This report contains national estimates of Americans' perceptions of the availability of various illicit drugs and of the risk of harm associated with their drug use. These 1992 estimates are part of an ongoing national survey. The report analyzes three basic perceptions concerning drugs: (1) the relationship between perceptions and use; (2)…

  3. Posthole Broadband Sensor Emplacement vs. Surface Vaults: Observations of Comparative Noise Performance and Trade-offs

    NASA Astrophysics Data System (ADS)

    Sweet, J. R.; Beaudoin, B. C.; Barstow, N.; Pfeifer, M.; Anderson, K. R.; Frassetto, A.

    2015-12-01

    Advances in seismometer design have diversified the range of instruments available for use in temporary field installations. IRIS programs, primarily PASSCAL and the Transportable Array (TA), have helped steer development of these new instruments to meet these evolving needs. PASSCAL operates a small pool of posthole broadband sensors, purpose built for direct burial. Near surface posthole installations are a new, cost effective, and logistically simple technique for broadband emplacement that is an alternative to the vault installations used in portable broadband seismic experiments for nearly 30 years. Direct burial installation is limited to the time and effort required to dig the borehole and emplace the sensor, thus reducing both material costs and time to install. Also, in Alaska, extreme environments and difficult logistics make standard TA tank vaults inappropriate for most sites. TA has developed improved deployment strategies for these environments. There, holes for posthole sensors are hammer- drilled or augered to several meters depth in soil, permafrost, or bedrock and then cased. These emplacement costs are generally less than standard TA vaults. We compare various installation techniques for test cases as well as general deployments of PASSCAL and TA stations. Automated noise performance analyses have been part of the TA throughout its operation, but until recently vault performance for portable installations supported by the PASSCAL program was sparse. In this study, we select a suite of co-located direct burial and surface vault installations and compare their noise performance using probability density functions. Our initial analyses suggest that direct burial sensors have lower noise levels than vault installations on both horizontal and vertical channels across a range of periods spanning <1 s to 100 s. However, most of these initial experiments for PASSCAL were with sensors not purpose built for direct burial and it became obvious that a sensor

  4. [Not Available].

    PubMed

    Bargues, L; Fall, M M

    2015-03-31

    Disaster situations involving mass burn casualties can occur at any time after a fire, a terrorist attack, an industrial explosion or a transport accident. The various burn societies in the world published recommendations on disaster burn-care planning. French burn society (Société Française d'Étude et de Traitement des Brûlures-SFETB) proposes triage of burned victims according to Total Burn Surface Area (TBSA), inhalation injury and associated traumatic injuries. This plan seeks to classify victims and to refer each burned patient to a bed suited to its needs (burn centre, surgical or medical ICU, Emergency room, surgical ward and triage). Emergency Medical Services play a pivotal role in this organisation: first care, advanced medical post, medical coordination, triage and transportation, additional equipment supply in proximal hospital. Burn disaster plan should be adapted to local medical resources. PMID:26668563

  5. The NHLBI Retrovirus Epidemiology Donor Studies (REDS and REDS-II): Twenty years of research to advance blood product safety and availability

    PubMed Central

    Kleinman, Steven; King, Melissa R; Busch, Michael P; Murphy, Edward L; Glynn, Simone A.

    2012-01-01

    The Retrovirus Epidemiology Donor Study (REDS), conducted from 1989–2001, and the Retrovirus Epidemiology Donor Study-II (REDS-II), conducted from 2004–2012, were National Heart Lung and Blood Institute (NHLBI) funded multicenter programs focused on improving blood safety and availability in the United States. REDS-II also included international study sites in Brazil and China. The three major research domains of REDS/REDS-II have been infectious disease risk evaluation, blood donation availability, and blood donor characterization. Both programs have made significant contributions to transfusion medicine research methodology by the use of mathematical modeling, large-scale donor surveys, innovative methods of repository sample storage, and establishing an infrastructure that responded to potential emerging blood safety threats such as XMRV. Blood safety studies have included protocols evaluating epidemiologic and/or laboratory aspects of HIV, HTLV I/II, HCV, HBV, WNV, CMV, HHV-8, B19V, malaria, CJD, influenza, and T. cruzi infections. Other analyses have characterized: blood donor demographics, motivations to donate, factors influencing donor return, behavioral risk factors, donors’ perception of the blood donation screening process, and aspects of donor deferral. In REDS-II, two large-scale blood donor protocols examined iron deficiency in donors and the prevalence of leukocyte antibodies. This review describes the major study results from over 150 peer-reviewed articles published by these two REDS programs. In 2011, a new seven year program, the Recipient Epidemiology and Donor Evaluation Study-III (REDS-III), was launched. REDS-III expands beyond donor-based research to include studies of blood transfusion recipients in the hospital setting, and adds a third country, South Africa, to the international program. PMID:22633182

  6. Broadband microwave spectroscopy of YBCO

    NASA Astrophysics Data System (ADS)

    Turner, Patrick James

    A novel low temperature bolometric method has been devised and implemented for high-precision measurements of the microwave surface resistance of small single-crystal platelet samples having very low absorption, as a continuous function of frequency from 0.5 GHz to 21 GHz. The key to the success of this non-resonant method is the in-situ use of a normal metal reference sample that calibrates the absolute rf field strength. The sample temperature can be controlled independently of the 1.2 K liquid helium bath, allowing for measurements of the temperature evolution of the absorption. Using this method, the minimum detectable power at 1.3 K is 1.5 pW, corresponding to a surface resistance sensitivity of approximately 1 muO for a typical 1 mm x 1 mm platelet sample. Using this apparatus, the zero-field electron spin resonance absorption spectrum of a dilute array of Gd ions substituted for Y in YBa2Cu 3O6+y was used as a unique means of accessing the absolute value of the low temperature magnetic penetration depth lambda( T → 0) in the Meissner state. The result is a new set of precise values of lambda for screening currents along the three principal crystallographic orientations in samples of GdxY1-xBa2Cu 3O6+y for three different oxygen-ordered phases having Tc values of 89 K, 75 K and 56 K. The in-plane values are found to depart substantially from the widely-reported relation Tc ∝ 1/lambda2 inferred mainly from muon spin relaxation measurements on polycrystalline materials. The broadband microwave spectrometer has allowed measurements in unprecedented detail of the in-plane microwave absorption in high-purity YBa2Cu 3O6+y single crystals. This has permitted, for the first time, the observation of the cusp shaped conductivity spectra characteristic of weak-limit scattering from impurities in a d-wave superconductor. A comparison of the detailed measurements for samples of ortho-II ordered YBa2Cu3O6.52 (Tc = 56 K) and fully-doped YBa2Cu3O6.993 ( Tc = 89 K) with

  7. Broadband absorption engineering of hyperbolic metafilm patterns

    NASA Astrophysics Data System (ADS)

    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.

  8. Broadband absorption engineering of hyperbolic metafilm patterns.

    PubMed

    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 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. PMID:24675706

  9. Broadband absorption engineering of hyperbolic metafilm patterns

    PubMed Central

    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 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. PMID:24675706

  10. Broadband antireflection coatings for multifunctional avionic displays

    NASA Astrophysics Data System (ADS)

    Kumari, Neelam; Kumar, Mukesh; Rao, P. K.; Karar, Vinod; Sharma, Amit Lochan

    2015-06-01

    Broadband Multilayer Antireflection (AR) coatings markedly improve the transmission efficiency of any optical component such as lens, prism, beam-splitter, beam combiner or a window. By reducing surface reflections over a wide wavelength range, broadband antireflection coatings improve transmission and enhance contrast which is desired in avionic displays. The broadband antireflection coating consisting of MgF2, ZrO2 and Al2O3 were designed to cover the whole visible spectrum and fabricated on optical grade glass substrate. The optical characterization of these coatings indicates reduction of the reflection to 2.28% as compared to 8.5 % at 545 nm (i.e. design wavelength of most avionic displays) for bare substrate making them useful in optical displays for avionic applications.

  11. Efficient Implementation of a Symbol Timing Estimator for Broadband PLC.

    PubMed

    Nombela, Francisco; García, Enrique; Mateos, Raúl; Hernández, Álvaro

    2015-01-01

    Broadband Power Line Communications (PLC) have taken advantage of the research advances in multi-carrier modulations to mitigate frequency selective fading, and their adoption opens up a myriad of applications in the field of sensory and automation systems, multimedia connectivity or smart spaces. Nonetheless, the use of these multi-carrier modulations, such as Wavelet-OFDM, requires a highly accurate symbol timing estimation for reliably recovering of transmitted data. Furthermore, the PLC channel presents some particularities that prevent the direct use of previous synchronization algorithms proposed in wireless communication systems. Therefore more research effort should be involved in the design and implementation of novel and robust synchronization algorithms for PLC, thus enabling real-time synchronization. This paper proposes a symbol timing estimator for broadband PLC based on cross-correlation with multilevel complementary sequences or Zadoff-Chu sequences and its efficient implementation in a FPGA; the obtained results show a 90% of success rate in symbol timing estimation for a certain PLC channel model and a reduced resource consumption for its implementation in a Xilinx Kyntex FPGA. PMID:26307999

  12. Rotor Broadband Noise Prediction with Comparison to Model Data

    NASA Technical Reports Server (NTRS)

    Brooks, Thomas F.; Burley, Casey L.

    2001-01-01

    This paper reports an analysis and prediction development of rotor broadband noise. The two primary components of this noise are Blade-Wake Interaction (BWI) noise, due to the blades' interaction with the turbulent wakes of the preceding blades, and "Self" noise, due to the development and shedding of turbulence within the blades' boundary layers. Emphasized in this report is the new code development for Self noise. The analysis and validation employs data from the HART program, a model BO-105 rotor wind tunnel test conducted in the German-Dutch Wind Tunnel (DNW). The BWI noise predictions are based on measured pressure response coherence functions using cross-spectral methods. The Self noise predictions are based on previously reported semiempirical modeling of Self noise obtained from isolated airfoil sections and the use of CAMRAD.Modl to define rotor performance and local blade segment flow conditions. Both BWI and Self noise from individual blade segments are Doppler shifted and summed at the observer positions. Prediction comparisons with measurements show good agreement for a range of rotor operating conditions from climb to steep descent. The broadband noise predictions, along with those of harmonic and impulsive Blade-Vortex Interaction (BVI) noise predictions, demonstrate a significant advance in predictive capability for main rotor noise.

  13. Two-mode squeezing in a broadband parametric amplifier

    NASA Astrophysics Data System (ADS)

    Grover, J. A.; Kamal, A.; Gustavsson, S.; Yan, F.; Orlando, T. P.; Oliver, W. D.; Hover, D.; Bolkhovsky, V.; Yoder, J. L.; Macklin, C.; O'Brien, K.; Siddiqi, I.

    The Josephson traveling wave parametric amplifier (JTWPA) exhibits gains of greater than 20 dB over a frequency range of a few gigahertz. In addition to being a quantum-limited amplifier over a wide frequency range, the JTWPA is a source of broadband squeezed radiation. We report the observation of broadband squeezing of microwave light generated by a JTWPA by measuring cross correlations between modes separated by up to one gigahertz in frequency. Employing a chain of two JTWPAs, the first as a squeezer and the second as a quantum-limited preamplifier, ensures a high-efficiency measurement of squeezing. We also discuss progress towards employing such two-mode squeezed radiation to realize high-fidelity dispersive readout of superconducting qubits. This research was funded in part by the U.S. Army Research Office Grant No. W911NF-14-1-0682 and by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA) and by the Assistant Secretary of Defense for Research & Engineering via MIT Lincoln Laboratory under Air Force Contract No. FA8721-05-C-0002.

  14. Broadband, Spectrally Flat, Graphene-based Terahertz Modulators.

    PubMed

    Shi, Fenghua; Chen, Yihang; Han, Peng; Tassin, Philippe

    2015-12-01

    Advances in the efficient manipulation of terahertz waves are crucial for the further development of terahertz technology, promising applications in many diverse areas, such as biotechnology and spectroscopy, to name just a few. Due to its exceptional electronic and optical properties, graphene is a good candidate for terahertz electro-absorption modulators. However, graphene-based modulators demonstrated to date are limited in bandwidth due to Fabry-Perot oscillations in the modulators' substrate. Here, a novel method is demonstrated to design electrically controlled graphene-based modulators that can achieve broadband and spectrally flat modulation of terahertz beams. In our design, a graphene layer is sandwiched between a dielectric and a slightly doped substrate on a metal reflector. It is shown that the spectral dependence of the electric field intensity at the graphene layer can be dramatically modified by optimizing the structural parameters of the device. In this way, the electric field intensity can be spectrally flat and even compensate for the dispersion of the graphene conductivity, resulting in almost invariant absorption in a wide frequency range. Modulation depths up to 76% can be achieved within a fractional operational bandwidth of over 55%. It is expected that our modulator designs will enable the use of terahertz technology in applications requiring broadband operation. PMID:26448571

  15. Efficient Implementation of a Symbol Timing Estimator for Broadband PLC

    PubMed Central

    Nombela, Francisco; García, Enrique; Mateos, Raúl; Hernández, Álvaro

    2015-01-01

    Broadband Power Line Communications (PLC) have taken advantage of the research advances in multi-carrier modulations to mitigate frequency selective fading, and their adoption opens up a myriad of applications in the field of sensory and automation systems, multimedia connectivity or smart spaces. Nonetheless, the use of these multi-carrier modulations, such as Wavelet-OFDM, requires a highly accurate symbol timing estimation for reliably recovering of transmitted data. Furthermore, the PLC channel presents some particularities that prevent the direct use of previous synchronization algorithms proposed in wireless communication systems. Therefore more research effort should be involved in the design and implementation of novel and robust synchronization algorithms for PLC, thus enabling real-time synchronization. This paper proposes a symbol timing estimator for broadband PLC based on cross-correlation with multilevel complementary sequences or Zadoff-Chu sequences and its efficient implementation in a FPGA; the obtained results show a 90% of success rate in symbol timing estimation for a certain PLC channel model and a reduced resource consumption for its implementation in a Xilinx Kyntex FPGA. PMID:26307999

  16. [Not Available].

    PubMed

    Palep, Jaydeep H

    2009-01-01

    The term "robot" was coined by the Czech playright Karel Capek in 1921 in his play Rossom's Universal Robots. The word "robot" is from the check word robota which means forced labor. The era of robots in surgery commenced in 1994 when the first AESOP (voice controlled camera holder) prototype robot was used clinically in 1993 and then marketed as the first surgical robot ever in 1994 by the US FDA. Since then many robot prototypes like the Endoassist (Armstrong Healthcare Ltd., High Wycombe, Buck, UK), FIPS endoarm (Karlsruhe Research Center, Karlsruhe, Germany) have been developed to add to the functions of the robot and try and increase its utility. Integrated Surgical Systems (now Intuitive Surgery, Inc.) redesigned the SRI Green Telepresence Surgery system and created the daVinci Surgical System((R)) classified as a master-slave surgical system. It uses true 3-D visualization and EndoWrist((R)). It was approved by FDA in July 2000 for general laparoscopic surgery, in November 2002 for mitral valve repair surgery. The da Vinci robot is currently being used in various fields such as urology, general surgery, gynecology, cardio-thoracic, pediatric and ENT surgery. It provides several advantages to conventional laparoscopy such as 3D vision, motion scaling, intuitive movements, visual immersion and tremor filtration. The advent of robotics has increased the use of minimally invasive surgery among laparoscopically naïve surgeons and expanded the repertoire of experienced surgeons to include more advanced and complex reconstructions. PMID:19547687

  17. Broadband diffractive lens or imaging element

    DOEpatents

    Ceglio, N.M.; Hawryluk, A.M.; London, R.A.; Seppala, L.G.

    1993-10-26

    A broadband diffractive lens or imaging element produces a sharp focus and/or a high resolution image with broad bandwidth illuminating radiation. The diffractive lens is sectored or segmented into regions, each of which focuses or images a distinct narrowband of radiation but all of which have a common focal length. Alternatively, a serial stack of minus filters, each with a diffraction pattern which focuses or images a distinct narrowband of radiation but all of which have a common focal length, is used. The two approaches can be combined. Multifocal broadband diffractive elements can also be formed. Thin film embodiments are described. 21 figures.

  18. Broadband mode conversion via gradient index metamaterials

    PubMed Central

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

    2016-01-01

    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. PMID:27098456

  19. Broadband mode conversion via gradient index metamaterials.

    PubMed

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

    2016-01-01

    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. PMID:27098456

  20. Numerical simulation for fan broadband noise prediction

    NASA Astrophysics Data System (ADS)

    Hase, Takaaki; Yamasaki, Nobuhiko; Ooishi, Tsutomu

    2011-03-01

    In order to elucidate the broadband noise of fan, the numerical simulation of fan operating at two different rotational speeds is carried out using the three-dimensional unsteady Reynolds-averaged Navier-Stokes (URANS) equations. The computed results are compared to experiment to estimate its accuracy and are found to show good agreement with experiment. A method is proposed to evaluate the turbulent kinetic energy in the framework of the Spalart-Allmaras one equation turbulence model. From the calculation results, the turbulent kinetic energy is visualized as the turbulence of the flow which leads to generate the broadband noise, and its noise sources are identified.

  1. Broadband diffractive lens or imaging element

    DOEpatents

    Ceglio, Natale M.; Hawryluk, Andrew M.; London, Richard A.; Seppala, Lynn G.

    1993-01-01

    A broadband diffractive lens or imaging element produces a sharp focus and/or a high resolution image with broad bandwidth illuminating radiation. The diffractive lens is sectored or segmented into regions, each of which focuses or images a distinct narrowband of radiation but all of which have a common focal length. Alternatively, a serial stack of minus filters, each with a diffraction pattern which focuses or images a distinct narrowband of radiation but all of which have a common focal length, is used. The two approaches can be combined. Multifocal broadband diffractive elements can also be formed. Thin film embodiments are described.

  2. Broadband diffractive lens or imaging element

    DOEpatents

    Ceglio, Natale M.; Hawryluk, Andrew M.; London, Richard A.; Seppala, Lynn G.

    1991-01-01

    A broadband diffractive lens or imaging element produces a sharp focus and/or a high resolution image with broad bandwidth illuminating radiation. The diffractive lens is sectored or segmented into regions, each of which focuses or images a distinct narrowband of radiation but all of which have a common focal length. Alternatively, a serial stack of minus filters, each with a diffraction pattern which focuses or images a distinct narrowband of radiation but all of which have a common focal length, is used. The two approaches can be combined. Multifocal broadband diffractive elements can also be formed.

  3. Cascaded metasurfaces for broadband antenna isolation

    NASA Astrophysics Data System (ADS)

    Shrekenhamer, David; Miragliotta, Joseph A.; Scott, Robert; Jablon, Allan; Friedman, Jerry; Harshbarger, Derek; Sievenpiper, Daniel F.

    2015-09-01

    In this paper, we present a computational and experimental design of a metasurface for broadband microwave antenna isolation. Our current emphasis is on the development of a high-impedance surface (HIS) that enables broadband isolation between transmit and receive antennas. For our specific HIS, we have formed a cascade of HIS unit cells and have thus expanded the isolation to provide 56 dB/meter over one octave (7.5 to 18 GHz) relative to the bare metal ground plane. Computational models are used to design the cascaded structure to assure maximum isolation amplitude and bandwidth.

  4. Cell broadband engine architecture as a DSP platform

    NASA Astrophysics Data System (ADS)

    Szumski, Karol; Malanowski, Mateusz

    2009-06-01

    The slowing pace of performance improvement in the commonly available processors is a cause of concern amongst many computational scientists. This combined with the ever increasing need for computational power has caused us to turn to alternative architectures in search of performance gains. Two main candidates were the Compute Unified Device Architecture (CUDA) and the Cell Broadband Engine (CELL BE) architecture. This paper focuses on the latter, outlining the architecture and basic programming paradigms, and also contains performance comparison of algorithms currently developed by our team.

  5. [Not Available].

    PubMed

    Trochu, Jean-Noël

    2014-10-01

    The World Health Organization defines Quality of life (QOL) as an individual's perception of their position in lfe in the context of the culture and value systems in which they live and in relation to their goals, expectations, standards and concerns. During chronic heart failure several factors contribute to the alteration of QOL: congestion, dyspnea, fatigue, sleep disturbances, anxiety, depression, side effects of medications, impacts on personal life and disruption of social interactions which can modify patients' social roles, life situation and ability to travel. NYHA class, exercise tolerance represent physician-reported patient well-being parameters but do not actually assess alterations expressed by the patient. There are several specific instruments to better evaluate QOL: they can be generic (self-assessment of general well-being), health related QOL (SF36), specific to diseases (Minnesota Living With Heart Failure Questionnaire) or domain specific (anxiety, depression). Impact of ACE inhibitors, angiotensin 2 antagonists, and beta-blockers are small while that of cardiac resynchronization and multidisciplinary management programmes are more efficient. In advanced heart failure when patient recognize equal importance between improvement in QOL and gain in survival, left ventricle assist devices (LVAD) significantly improve QOL at early (3 months) and long-term (2 years) follow up. LVADs allow the rapid return of the patients at home and genuine autonomy in the context of a personalized care plan supervised by the referring centre. Beneficial effects are close to those of heart transplantation but still are limited by the need of taking care of their equipment. PMID:27120907

  6. 47 CFR 27.1217 - Competitive bidding procedures for the Broadband Radio Service.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Broadband Radio Service. 27.1217 Section 27.1217 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27.1217 Competitive bidding procedures for the Broadband...

  7. 47 CFR 27.1217 - Competitive bidding procedures for the Broadband Radio Service.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Broadband Radio Service. 27.1217 Section 27.1217 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27.1217 Competitive bidding procedures for the Broadband...

  8. 47 CFR 27.1217 - Competitive bidding procedures for the Broadband Radio Service.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Broadband Radio Service. 27.1217 Section 27.1217 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27.1217 Competitive bidding procedures for the Broadband...

  9. 47 CFR 27.1217 - Competitive bidding procedures for the Broadband Radio Service.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Broadband Radio Service. 27.1217 Section 27.1217 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27.1217 Competitive bidding procedures for the Broadband...

  10. 47 CFR 27.1217 - Competitive bidding procedures for the Broadband Radio Service.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Broadband Radio Service. 27.1217 Section 27.1217 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27.1217 Competitive bidding procedures for the Broadband...

  11. [Not Available].

    PubMed

    Oddo, Antonio

    2016-01-01

    This new paper on chemical risk from anaesthetic agents in operating theatres is the natural progression of that published in this journal in supplement 1-2013, as it constitutes a development and complement of the previous work and an applicative confirmation from the highest organ of administrative justice, the Consiglio di Stato, regarding, in particular, the obligation of adopting the technically most advanced "measures" to eliminate or, at least, minimise risk in the use of new generation and the most commonly-used anaesthetic agents (sevoflurane and desflurane). Therefore, in this paper, the authors commence by referring to the starting point, consisting in the conclusions of the previous study, which highlighted the extraordinary convergence of technical and scientific, legislative and case law data on the same result, constituted by the possibility, and consequent obligation, of implementing, also in operating theatres, the greatest technologically possible safety, starting with the choice of the most suitable equipment, methods and quality systems for avoiding the diffusion, dispersion and /or leakage of volatile hazardous agents that may contribute - together with those chemical reactions that are foreseeable and avoidable, given the characteristics of the materials, substances and relative "packaging" - to workplace pollution, which can, in any case, reach levels that are hazardous due to the concentration of anaesthetic gases. Subsequently, once the "scientific" fruit of the previous contributions has been discussed, the authors evaluate the impact of the result already achieved in practice with concrete cases and the judgement expressed with a series of judgements issued in rapid succession by the Consiglio di Stato, showing the application, not merely of the legislative "data" but also of the references and citations that these "data" contain regarding the "knowledge acquired regarding the relationship with technical progress". Lastly, the Authors

  12. An experimental investigation of helicopter rotor high frequency broadband noise

    NASA Technical Reports Server (NTRS)

    Lee, A.; Aravamudan, K. S.; Bauer, P.; Harris, W. L.

    1977-01-01

    The paper describes experiments involving a 4.17 foot diameter model rotor operating in a 5 times 7.5 ft open jet wind tunnel enclosed in an anechoic chamber. The effects of rotor thrust, advance ratio, and the number of blades on the intensity and spectrum of high frequency broadband noise (HFBN) have been investigated. The effects of each parameter were determined by keeping the other two constant. The directivities of the two- and three-bladed rotors were measured in a direction perpendicular to the plane of the rotor disk. The effects of heading edge, pressure side, and suction side serrations on HFBN were measured under several operating conditions, and the effects of the serrations on the mean thrust generated by the rotor were studied. A scaling law is proposed to determine the location of the peak frequency and intensity of HFBN.

  13. 47 CFR 90.528 - Public safety broadband license.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Public safety broadband license. 90.528 Section... the 763-775 and 793-805 MHz Bands § 90.528 Public safety broadband license. (a) The 763-768/793-798 MHz bands are allocated on a nationwide basis for public safety broadband operations and licensed to...

  14. 47 CFR 27.1305 - Shared wireless broadband network.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Shared wireless broadband network. 27.1305... MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES 700 MHz Public/Private Partnership § 27.1305 Shared wireless broadband network. The Shared Wireless Broadband Network developed by the 700 MHz Public/Private...

  15. 47 CFR 90.1405 - Shared wireless broadband network.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Shared wireless broadband network. 90.1405... SERVICES PRIVATE LAND MOBILE RADIO SERVICES 700 MHz Public/Private Partnership § 90.1405 Shared wireless broadband network. The Shared Wireless Broadband Network developed by the 700 MHz Public/Private...

  16. 47 CFR 90.528 - Public safety broadband license.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Public safety broadband license. 90.528 Section... the 763-775 and 793-805 MHz Bands § 90.528 Public safety broadband license. (a) The 763-768/793-798 MHz bands are allocated on a nationwide basis for public safety broadband operations and licensed to...

  17. Broadband acoustic source processing in a noisy shallow ocean environment

    SciTech Connect

    Candy, J.V.; Sullivan, E.J.

    1996-07-18

    Acoustic sources found in the ocean environment are spatially complex and broadband, complicating the analysis of received acoustic data considerably. A model-based approach is developed for a broadband source in a shallow ocean environment characterized by a normal-mode propagation model. Here we develop the optimal Bayesian solution to the broadband pressure-field enhancement and modal function extraction problem.

  18. 47 CFR 90.19 - Nationwide Public Safety Broadband Network.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Nationwide Public Safety Broadband Network. 90... Safety Broadband Network. Pursuant to the Middle Class Tax Relief and Job Creation Act of 2012, Public... First Responder Network Authority to deploy a nationwide public safety broadband network as...

  19. 47 CFR 90.19 - Nationwide Public Safety Broadband Network.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Nationwide Public Safety Broadband Network. 90... Safety Broadband Network. Pursuant to the Middle Class Tax Relief and Job Creation Act of 2012, Public... First Responder Network Authority to deploy a nationwide public safety broadband network as...

  20. 75 FR 29516 - Broadband Researchers' Data Workshop

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-26

    ... a public meeting concerning the nature of data related to broadband Internet access and use that the... the following topics, including specific areas of inquiry: 1. Internet access at home and outside the home. 2. Internet use at home and outside the home. 3. Computer access at home and outside the home....

  1. 75 FR 14131 - Broadband Technology Opportunities Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-24

    ... National Telecommunications and Information Administration RIN 0660-ZA28 Broadband Technology Opportunities... procedures for the second round of BTOP funding. (75 FR 3792, Jan. 22, 2010). In the Second NOFA, NTIA... http://www.broadbandusa.gov . (75 FR at 3805). NTIA established an application window for BTOP...

  2. Localization of aerial broadband noise by pinnipeds

    NASA Astrophysics Data System (ADS)

    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.

  3. The GREGOR Broad-Band Imager

    NASA Astrophysics Data System (ADS)

    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.

  4. Broadband Satellite Technologies and Markets Assessed

    NASA Technical Reports Server (NTRS)

    Wallett, Thomas M.

    1999-01-01

    The current usage of broadband (data rate greater than 64 kilobits per second (kbs)) for multimedia network computer applications is increasing, and the need for network communications technologies and systems to support this use is also growing. Satellite technology will likely be an important part of the National Information Infrastructure (NII) and the Global Information Infrastructure (GII) in the next decade. Several candidate communications technologies that may be used to carry a portion of the increased data traffic have been reviewed, and estimates of the future demand for satellite capacity have been made. A study was conducted by the NASA Lewis Research Center to assess the satellite addressable markets for broadband applications. This study effort included four specific milestones: (1) assess the changing nature of broadband applications and their usage, (2) assess broadband satellite and terrestrial technologies, (3) estimate the size of the global satellite addressable market from 2000 to 2010, and (4) identify how the impact of future technology developments could increase the utility of satellite-based transport to serve this market.

  5. Broadband Heterodyne SIS Spectrometer Prototype: First Results

    NASA Technical Reports Server (NTRS)

    Rice, F.; LeDuc, H.; Harris, A.; Hu, S.; Sumner, M.; Zmuidzinas, J.

    2004-01-01

    The broadband heterodyne SIS receiver system described elsewhere (reference 1) has been assembled and tested both in the laboratory and during two observing runs on the Cassegrain focus of the 10 meter telescope at the Caltech Submillimeter Observatory on Mauna Kea, Hawaii. Here we present a brief summary of the initial results.

  6. Bandwidth, Broadband, and Planning for Public Access

    ERIC Educational Resources Information Center

    Blowers, Helene

    2012-01-01

    Broadband and bandwidth allocation is an essential technology planning activity that libraries should address on a continual basis. There are five key factors that will impact your network's performance: 1. infrastructure, 2. network load, 3. workstation performance, 4. prioritization of services, and 5. network management. The author thinks it's…

  7. [Not Available].

    PubMed

    Kautzky-Willer, Alexandra

    2016-03-01

    Obesity is increasing worldwide in both sexes and a challenge for health professionals and the health care system. Women have more subcutaneous fat and are more insulin sensitive while men have more visceral and liver fat and higher cardiovascular risk. Women more often show the metabolically healthy obese phenotype than males. However, with increasing BMI the risk for type 2 diabetes and cardiovascular diseases increases more dramatically in women compared to males. Obese women suffer more from weight-related problems, have a higher rate of depression and seek more often medical help to reduce weight. Both biological factors and psychosocial factors contribute to the disease and interact with each other. In this special edition of the journal sex and gender aspects in prevention, treatment and development of complications will be discussed, as proposed by the Austrian Obesity Association. Data available from the Austrian population will be included in the Austrian Gender Obesity Report. PMID:26847444

  8. [Not Available].

    PubMed

    Blanchard, Elodie; de Lara, Manuel Tunon

    2013-01-01

    Pholcodine is an opioid that has been widely used worldwide since 1950 for the treatment of non-productive cough in children and adults. The results of early preclinical studies but also those of recent clinical trials have shown the antitussive efficacy of pholcodine to be superior to that of codeine, of longer duration, and with an equivalent or safer toxicity profile. Also, there is no risk of addiction. Concern had been raised over a possible cross-sensitisation with neuromuscular blocking agents. While a recent assessment of the available data by the European Medicines Agency (EMA) has confirmed the favourable risk-benefit ratio of pholcodine, further studies are needed to clear this point. PMID:27392673

  9. [Not Available].

    PubMed

    Olsen, Björn; Lundkvist, Åke

    2016-01-01

    Zika virus is a mosquito-borne flavivirus transmitted by Aedes mosquitos. The virus was discovered in 1947 in the Zika forest in Uganda. Symptomatic disease is usually mild and is characterized by maculopapular rash, headache, fever, arthralgia and conjunctivitis. Fatalities are rare. There is neither vaccine nor curative treatment available. In May 2015, the first observation of local virus transmission was reported from Brazil. During the expanding outbreak in the Americas, Zika virus infection has been associated with microcephaly in newborn and fetal losses in women infected with Zika virus during pregnancy. The main reason for the current epidemic in the Americas is the introduction of an Old World virus into a new ecosystem, with no background herd immunity in the population. It is likely that the spread of Zika virus will continue, affecting all countries in the Americas except for Chile and Canada. PMID:26978815

  10. [Not Available].

    PubMed

    Forstner, Christina; Pletz, Mathias W

    2016-02-01

    Infections with multi-drug resistant bacteria are increasing worldwide. Glycopeptides, linezolid, daptomycin and 5th generation cephalosporins ("MRSA-cephalsoporins") are used against severe infections with MRSA, combination partners are rifampin and fosfomycin. Treatment options against VRE-infections are limited to linezolid, daptomycin and tigecyclin. New agents with activity against MRSA and VRE are tedizolid, dalbvancin and oritavancin. For monotherapy of severe infections due to 3MRGN carbapenems are available. Ceftolozane/tazobactam has been licensed by the European Medical Agency and shows good activity against a relevant proportion of ESBL-pathogens. Oral agents such as nitrofurantoin or fosfomycin are used for treatment of uncomplicated cystitis. Colistin shows best in vitro susceptibility against carbapenem-resistant Enterobacteriaceae, followed by fosfomycin and tigecycline. For serious infections with 4MRGN a colistin-based combination treatment with two to three agents is recommended. In such cases a carbapenem as combination partner may be useful. PMID:26949908

  11. Advanced Technology: It's Available at JPL

    NASA Technical Reports Server (NTRS)

    Edberg, James R.

    1996-01-01

    Non-NASA activities at JPL are the province of the JPL Technology and Applications Programs Directorate, and include working relationships with industry, academia, and other government agencies. Within this Directorate, the JPL Undersea Technology Program endeavors to apply and transfer these capabilities to the area of underwater research and operations. Of particular interest may be a Reversed Electron Attachment Detector (READ). It is a man-portable device capabable of unambiguous detection of unique chemical signatures associated with mines. In addition, there are other JPL technologies which merit investigation for marine applications.

  12. Observations of Auroral Broadband Emissions by CLUSTER

    NASA Astrophysics Data System (ADS)

    Wahlund, J.-E.; et al.

    2003-04-01

    We present the results of a study based on several events of auroral broadband ULF/ELF emissions observed by the CLUSTER multi-spacecraft at distances around 4-5 RE. These emissions, observed below the ion plasma frequency, have similar dispersion characteristics as the broadband emissions observed at lower altitudes (800-4000 km) by e.g. rockets (e.g. AMICIST) and satellites (e.g. FREJA and FAST). As successive passages of the four CLUSTER satellites through nearly the same regions show, the intensity of the emissions depend on the thermal properties of the plasma and gradients thereof. The total Poynting flux is downward and is comparable to energy fluxes observed at lower altitudes. We therefore believe that the broadband emissions observed by CLUSTER in the auroral region are consistent with dispersed linear polarised Alfvén waves (DAW) transporting energy downward to the ionosphere guided by the magnetic field lines. These waves are therefore an important aspect for the energy transport for the auroral processes leading to particle acceleration when dissipating part or all their energy along the propagation path by wave-particle coupling, causing ion heating, suprathermal electron bursts and higher frequency ion-mode waves and possibly also electric potential structures. Intermittent auroral arc features have been observed embedded in a larger region of broadband emissions. The multi-spacecraft measurements by CLUSTER here show the temporal development of sharp density gradients and intensified broadband waves together with the formation of electric potential structures and particle acceleration within the larger scale density cavity.

  13. Helicity multiplexed broadband metasurface holograms

    PubMed Central

    Wen, Dandan; Yue, Fuyong; Li, Guixin; Zheng, Guoxing; Chan, Kinlong; Chen, Shumei; Chen, Ming; Li, King Fai; Wong, Polis Wing Han; Cheah, Kok Wai; Yue Bun Pun, Edwin; Zhang, Shuang; Chen, Xianzhong

    2015-01-01

    Metasurfaces are engineered interfaces that contain a thin layer of plasmonic or dielectric nanostructures capable of manipulating light in a desirable manner. Advances in metasurfaces have led to various practical applications ranging from lensing to holography. Metasurface holograms that can be switched by the polarization state of incident light have been demonstrated for achieving polarization multiplexed functionalities. However, practical application of these devices has been limited by their capability for achieving high efficiency and high image quality. Here we experimentally demonstrate a helicity multiplexed metasurface hologram with high efficiency and good image fidelity over a broad range of frequencies. The metasurface hologram features the combination of two sets of hologram patterns operating with opposite incident helicities. Two symmetrically distributed off-axis images are interchangeable by controlling the helicity of the input light. The demonstrated helicity multiplexed metasurface hologram with its high performance opens avenues for future applications with functionality switchable optical devices. PMID:26354497

  14. Helicity multiplexed broadband metasurface holograms.

    PubMed

    Wen, Dandan; Yue, Fuyong; Li, Guixin; Zheng, Guoxing; Chan, Kinlong; Chen, Shumei; Chen, Ming; Li, King Fai; Wong, Polis Wing Han; Cheah, Kok Wai; Pun, Edwin Yue Bun; Zhang, Shuang; Chen, Xianzhong

    2015-01-01

    Metasurfaces are engineered interfaces that contain a thin layer of plasmonic or dielectric nanostructures capable of manipulating light in a desirable manner. Advances in metasurfaces have led to various practical applications ranging from lensing to holography. Metasurface holograms that can be switched by the polarization state of incident light have been demonstrated for achieving polarization multiplexed functionalities. However, practical application of these devices has been limited by their capability for achieving high efficiency and high image quality. Here we experimentally demonstrate a helicity multiplexed metasurface hologram with high efficiency and good image fidelity over a broad range of frequencies. The metasurface hologram features the combination of two sets of hologram patterns operating with opposite incident helicities. Two symmetrically distributed off-axis images are interchangeable by controlling the helicity of the input light. The demonstrated helicity multiplexed metasurface hologram with its high performance opens avenues for future applications with functionality switchable optical devices. PMID:26354497

  15. Generation of bright broadband-squeezed light and broadband quantum interferometry

    NASA Astrophysics Data System (ADS)

    Xie, Daruo

    Generation of bright broadband squeezed light is of great interest from the viewpoint of experimental and applied physics. Squeezed states of the light field can be used for ultrasensitive interferometry measurements. Broadband light squeezing also can find a direct application as classical channel capacity enhancement in broadband coherent optical communication. A degenerate (type-I) optical parametric amplifier (OPA), which is based on a periodically poled nonlinear crystal, has been built for research in quantum optics, to provide a source of broadband squeezed light. Through parametric down-conversion process in the nonlinear crystal, energy of pump light was converted to OPA's output 1064 nm light, and the output light is phase-quadrature broadband squeezed. Moreover, the OPA has been operated in the state of a free-running emitter with no servo loops for cavity length control and phase control to verify the intrinsic stability of the OPA. Sensitivity enhancement of optical interferometry has been observed by homodyne detection measurements with the OPO-generated broadband squeezed light as an input beam. This experiment is also a demonstration of the increase of the classical channel capacity beyond that of a coherent state in coherent optical communication.

  16. [Not Available].

    PubMed

    Marugán de Miguelsanz, José Manuel; Torres Hinojal, María Del Carmen; Geijo Uribe, María Soraya; Redondo Del Río, María Paz; Mongil López, Beatriz; De Brito García-Sousa, Inés; Caballero Sanz, Irene; Eiros Bouza, José María

    2016-01-01

    Anorexia nervosa (AN) is the most prevalent of eating disorders in children and adolescents, and its treatment is long and complex, involving a multidisciplinary team. Nutritional rehabilitation and restoration of a healthy body weight is one of the central goals in the initial stages of inpatient treatment. However, current recommendations on initial energy requirements for these patients are inconsistent, with a clear lack of controlled studies, available scientific evidence and global consensus on the most effective and safe refeeding practices in hospitalized adolescents with anorexia nervosa (AN). Conservative refeeding recommendations have been classically established in order to prevent the refeeding syndrome. Nevertheless, various works have recently appeared advocating a higher initial caloric intake, without observing more complications or refeeding syndrome, and allowing a shorter average stay. We present our experience in the treatment of restricting AN with a conservative progressive treatment. We have obtained good results with this approach, which was well tolerated by patients, with no observing complications. As a consequence, the medical team could establish a pact about the therapeutic goals with the patients in an easier way. PMID:27444457

  17. [Not Available].

    PubMed

    Marugán de Miguelsanz, José Manuel; Torres Hinojal, María Del Carmen; Geijo Uribe, María Soraya; Redondo Del Río, María Paz; Mongil López, Beatriz; De Brito García-Sousa, Inés; Caballero Sanz, Irene; Eiros Bouza, José María

    2016-01-01

    Anorexia nervosa (AN) is the most prevalent of eating disorders in children and adolescents, and its treatment is long and complex, involving a multidisciplinary team. Nutritional rehabilitation and restoration of a healthy body weight is one of the central goals in the initial stages of inpatient treatment. However, current recommendations on initial energy requirements for these patients are inconsistent, with a clear lack of controlled studies, available scientific evidence and global consensus on the most effective and safe refeeding practices in hospitalized adolescents with anorexia nervosa (AN). Conservative refeeding recommendations have been classically established in order to prevent the refeeding syndrome. Nevertheless, various works have recently appeared advocating a higher initial caloric intake, without observing more complications or refeeding syndrome, and allowing a shorter average stay. We present our experience in the treatment of restricting AN with a conservative progressive treatment. We have obtained good results with this approach, which was well tolerated by patients, with no observing complications. As a consequence, the medical team could establish a pact about the therapeutic goals with the patients in an easier way. PMID:27513485

  18. [Not Available].

    PubMed

    Chaibdraa, A; Medjelekh, M S; Saouli, A; Bentakouk, M C

    2015-09-30

    Use of local/regional anesthesia in burn patients is limited by many factors. It is considered as marginal in the multimodal treatment of nociceptive pain. We conducted a retrospective study on regional anesthesia used for analgesia over a period of three years. Given the lack of available literature on this subject, the results obtained from this study will enable suggestions to be made for possible uses of this technique. We identified 634 uses of regional anesthesia of which 96% were in adults. Most cases involved the lower limbs (76%). Spinal anesthesia was performed on 32 patients, including four children. Incidents were infrequent (3%) and had no morbid consequence. Regional anesthesia may be a useful option in a multimodal strategy of analgesia, allowing early passive rehabilitation and recovery after surgical skin grafts. It should be assessed in outpatients, since 95% of burns patients are not hospitalized. Use of regional anesthesia in burn patients should generate more interest to allow the establishment of protocols in multidisciplinary reflection. PMID:27279806

  19. [Not Available].

    PubMed

    Goffinet, L; Breton, A; Gavillot, C; Barbary, S; Journeau, P; Lascombes, P; Dautel, G

    2015-09-30

    The early management of pediatric hand burns includes surgical treatment, medical follow up and prevention of abnormal scarring by splits and/or pressure garment therapy. The aim of this review was to find the best available evidence in the literature on the surgical part of this management. This review started with a search in the PubMed database for the keywords, hand AND/OR child AND/OR burn. Only the articles published between January 1(st), 2005 and January 1(st), 2011 were selected. The data were compared to French and American textbooks. Contradictory findings were reported on the timing of the excision and graft, with only two comparative studies reported, with a lot of biases. The state of the art on the initial management of hand burns in children is not totally conclusive due to the lack of statistic power in these studies, but many expert opinions help to define options for good therapeutic paradigms. It is important to include these patients in prospective protocols with both early and long-term follow-up in order to increase the amount of evidence at our disposal. PMID:27279807

  20. Ultra-broadband plasmonic super absorbers for universal surface enhanced Raman spectroscopy substrate (Presentation Recording)

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    Although Raman spectroscopy has been commercialized, low-cost and large-area surface enhanced Raman spectroscopy (SERS) substrates with localized enhanced field are heavily required. However, currently dominant manufacturing techniques are expensive and complicated for large-area fabrication. Furthermore, most SERS substrates can only be used for individual excitation wavelengths. In this work, we will report an ultra-broadband super absorbing metasurface to enhance SERS signals in a broadband region (i.e. from 450 nm to 1000 nm). The design consisting of an Ag ground plate, a SiO2 spacer, and a layer of Ag nanoparticles was fabricated using simple film deposition and thermal annealing techniques. A broadband absorption over 80% from 414 nm to 956 nm was obtained, resulting in localized field enhancement between adjacent nanoparticles. We employed this metasurface to test its broadband SERS signal by adsorbing 1,2-Bis(4-pyridyl)-ethylene (BPE) molecules on top of it. We employed 5 laser lines (i.e., 514, 532, 633, 671 and 785 nm) to excite the sample and observed fingerprint signature of BPE molecules under all 5 excitation wavelengths with the average enhancement factor up to 5.3×107. Therefore, the designed SERS substrate can work for almost "all" available excitation wavelengths over a broadband, which is particularly useful for sensing a broad spectrum of chemicals on the same chip.

  1. [Not Available].

    PubMed

    Demaeyer, Ph

    2016-01-01

    Medicine owes many to Hippocrate, but pneumology traces its origin back to antiquity, from Mesopotamia to ancient Rome. Regarding prehistory: if viscera of this period have not been kept, some bones were. Since Neanderthals, it is then possible to study osteoarticular pathologies (often chronic arthrosis). But no evidence of tuberculosis was found (all thoracic kyphosis are not tuberculosis). Tuberculosis probably appears during the Neolithic age, because of high concentration of population. In ancient times, pneumology was of course not a real medical specialty. However, respiratory illness already constituted a big part of antique medical practice. The purpose of the physician in antiquity was to establish a diagnosis, a prognostic and to propose a treatment. Prognostic revealed to be of great importance in ancient times, since therapeutic efficacy was limited. Contemporary physicians often neglect this part of their practice. In ancient times, physicians also tried to gradually eliminate magic-religious aspects in taking care of the patients. This review will propose a journey from Mesopotamia to ancient Egypt (and its medical papyrus). Very few sources are available concerning medicine in pre-Columbian cultures. However, it is well known that shamans had, besides their religious competences, a great pharmacopoeia. Because of these very few sources, this topic will not be added to this article. Little is known in Europa about chinese medicine before the Jesuit mission in China during the 17th and 18th centuries. Yet, chinese medicine grew in parallel with European's one. Some relevant elements of this medicine will hereafter be shown. PMID:27120938

  2. [Not Available].

    PubMed

    Soret, Juliette; Kiladjian, Jean-Jacques

    2016-06-01

    THE ROLE OF RUXOLITINIB IN THE TREATMENT OF MYELOPROLIFERATIVE NEOPLASMS: The discovery of the JAK2V617F mutation in 2005, present in 95% of polycythemia vera (PV) and in 55% of myelofibrosis (MF) patients, opened the way for a new era of targeted therapies for myeloproliferative neoplasms. Ruxolitinib was the first-in-class Janus Kinase (JAK) inhibitor approved for the management of these diseases. In PV patients, conventional treatment strategies including aspirin, phlebotomy, cytoreductive agents such as hydroxyurea and interferon, clearly provide clinical benefits. However, some patients develop resistance or intolerance to these treatments. Ruxolitinib has been approved for PV patients who are resistant to or intolerant of hydroxyurea, based on the results of the phase 3 RESPONSE study. This study showed that ruxolitinib improves hematocrit control, reduces splenomegaly, and ameliorate disease-related symptoms as compared with best available therapy. In MF patients, the only curative treatment is allogeneic stem cell transplantation, but it remains restricted to a limited group of patients with poor prognosis and who are eligible for such procedure associated with non-negligible transplant-related mortality. Other treatments are palliative and unlikely to prolong survival. Ruxolitinib has been approved in the United States for MF patients with intermediate or high-risk disease, and in Europe for disease-related splenomegaly or symptoms in adults with MF, based on phase 3 COMFORT-I and COMFORT-II studies. These studies showed that ruxolitinib was able to reduce splenomegaly, ameliorate symptoms, and improve survival. However, the journey is not finished yet since there are still important unmet needs for MF patients, including improvement in cytopenias, and significant modification of disease natural history. PMID:27494970

  3. Ambient seismic noise cross-correlations at Romanian broadband stations

    NASA Astrophysics Data System (ADS)

    Grecu, Bogdan; Tataru, Dragos; Neagoe, Cristian; Panza, Giuliano; Raileanu, Victor; Radulian, Mircea; Popa, Mihaela; Ionescu, Constantin

    2010-05-01

    In the last years the National Institute for Earth Physics (NIEP), Romania, has developed its real-time broadband seismic network. At present, NIEP operates 34 stations with both broadband velocity sensors (CMG3ESP, CMG40T, KS2000, STS2) and accelerometer sensors (2gEpi). The data are continuously recorded and transmitted to the Romanian Data Centre where Antelope 4.11 is running for acquisition and processing. The density of the stations produces 560 inter-station pairs for ambient noise cross-correlation analysis. In this study, we used seismic data recorded during a period of 12 months, between January 2009 and December 2009. A nonlinear procedure is applied to lower the influence of the earthquake-related signals and to obtain a symmetric noise cross-correlation function (for details see Cho et al., 2007). The results show good cross-correlation functions for almost all pair of stations. As the vertical components of ambient noise are cross-correlated, only the fundamental mode of the Rayleigh wave is obtained. The FTAN analysis is used to extract the group velocities from the estimated dispersive waves at periods between 6 and 30 sec. This work provides very useful data for future tomographic studies in Romania at crustal level, considering that new data from other broadband stations deployed on the Romanian territory will become available. References: Cho, K.H., R. B. Herrmann, C. J. Ammon and K. Lee. Imaging the Upper Crust of the Korean Peninsula by Surface-Wave Tomography, Bulletin of the Seismological Society of America (2007) 97, 198-207.

  4. Broadband passive optical network media access control protocols

    NASA Astrophysics Data System (ADS)

    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.

  5. Recent Results from Broad-Band Intensity Mapping Measurements of Cosmic Large Scale Structure

    NASA Astrophysics Data System (ADS)

    Zemcov, Michael B.; CIBER, Herschel-SPIRE

    2016-01-01

    Intensity mapping integrates the total emission in a given spectral band over the universe's history. Tomographic measurements of cosmic structure can be performed using specific line tracers observed in narrow bands, but a wealth of information is also available from broad-band observations performed by instruments capable of capturing high-fidelity, wide-angle images of extragalactic emission. Sensitive to the continuum emission from faint and diffuse sources, these broad-band measurements provide a view on cosmic structure traced by components not readily detected in point source surveys. After accounting for measurement effects and astrophysical foregrounds, the angular power spectra of such data can be compared to predictions from models to yield powerful insights into the history of cosmic structure formation. This talk will highlight some recent measurements of large scale structure performed using broad-band intensity mapping methods that have given new insights on faint, distant, and diffuse components in the extragalactic background light.

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

    PubMed

    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

  7. Broadband optical serrodyne frequency shifting.

    PubMed

    Johnson, D M S; Hogan, J M; Chiow, S-w; Kasevich, M A

    2010-03-01

    We demonstrate serrodyne frequency shifting of light from 200 MHz to 1.2 GHz with an efficiency of better than 60%. The frequency shift is imparted by an electro-optic phase modulator driven by a high-frequency high-fidelity sawtooth waveform that is passively generated by a commercially available nonlinear transmission line. We also implement a push-pull configuration using two serrodyne-driven phase modulators, allowing for continuous tuning between -1.6 GHz and +1.6 GHz. Compared with competing technologies, this technique is simple and robust, and it offers the largest available tuning range in this frequency band. PMID:20195339

  8. Broadband Access and Implications for Efforts to Address Equity Gaps in Postsecondary Attainment

    ERIC Educational Resources Information Center

    Sisneros, Lauren; Sponsler, Brian A.

    2016-01-01

    This education trends report focuses on two related but distinct challenges confronting state policy leaders and students as they seek to leverage online distance education to meet personal and statewide education goals: (1) access to the infrastructure necessary to provide industry-standard broadband speeds and (2) ensuring availability of the…

  9. Broadband single-molecule excitation spectroscopy

    PubMed Central

    Piatkowski, Lukasz; Gellings, Esther; van Hulst, Niek F.

    2016-01-01

    Over the past 25 years, single-molecule spectroscopy has developed into a widely used tool in multiple disciplines of science. The diversity of routinely recorded emission spectra does underpin the strength of the single-molecule approach in resolving the heterogeneity and dynamics, otherwise hidden in the ensemble. In early cryogenic studies single molecules were identified by their distinct excitation spectra, yet measuring excitation spectra at room temperature remains challenging. Here we present a broadband Fourier approach that allows rapid recording of excitation spectra of individual molecules under ambient conditions and that is robust against blinking and bleaching. Applying the method we show that the excitation spectra of individual molecules exhibit an extreme distribution of solvatochromic shifts and distinct spectral shapes. Importantly, we demonstrate that the sensitivity and speed of the broadband technique is comparable to that of emission spectroscopy putting both techniques side-by-side in single-molecule spectroscopy. PMID:26794035

  10. Integrated broadband bowtie antenna on transparent substrate

    NASA Astrophysics Data System (ADS)

    Zhang, Xingyu; Wang, Shiyi; Subbaraman, Harish; Zhan, Qiwen; Pan, Zeyu; Chung, Chi-jui; Yan, Hai; Chen, Ray T.

    2015-03-01

    The bowtie antenna is a topic of growing interest in recent years. In this paper, we design, fabricate, and characterize a modified gold bowtie antenna integrated on a transparent glass substrate. We numerically investigate the antenna characteristics, specifically its resonant frequency and enhancement factor. We simulate the dependence of resonance frequency on bowtie geometry, and verify the simulation results through experimental investigation, by fabricating different sets of bowtie antennas on glass substrates utilizing CMOS compatible processes and measuring their resonance frequencies. Our designed bowtie antenna provides a strong broadband electric field enhancement in its feed gap. The far-field radiation pattern of the bowtie antenna is measured, and it shows dipole-like characteristics with large beam width. Such a broadband antenna will be useful for a myriad of applications, ranging from wireless communications to electromagnetic wave detection.

  11. Inverse Doppler Effects in Broadband Acoustic Metamaterials.

    PubMed

    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

  12. Terahertz broadband spectroscopic investigations of amino acid

    NASA Astrophysics Data System (ADS)

    Zhu, De-chong; Zhang, Liang-liang; Zhong, Hua; Zhang, Cun-lin

    2011-08-01

    We present an experimental terahertz (THz) spectroscopic investigation of amino acid using an air-breakdown-coherent detection (ABCD) system. The strong and ultra-broadband (0.1 to 10THz) terahertz radiations generated by two-color laser induced air plasma and measured by coherent heterodyne detection. The broadband THz reflection spectra of L-Lysine (C6H14N2O2) and L-Arginine (C6H14N2O2) are obtained. To solve the phase-retrieval problem in RTDS, the absorption signatures of the materials are extracted directly from the first derivative of the relative reflectance with respect to frequency. The absorption features of the two amino acids are characterized in the 0.5~6 THz region. It is found that both the two amino acids have an absorption peak at 1.10 THz.

  13. Broadband Visible Light Induced NO Formation

    NASA Astrophysics Data System (ADS)

    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.

  14. High-Resolution Broadband Spectral Interferometry

    SciTech Connect

    Erskine, D J; Edelstein, J

    2002-08-09

    We demonstrate solar spectra from a novel interferometric method for compact broadband high-resolution spectroscopy. The spectral interferometer (SI) is a hybrid instrument that uses a spectrometer to externally disperse the output of a fixed-delay interferometer. It also has been called an externally dispersed interferometer (EDI). The interferometer can be used with linear spectrometers for imaging spectroscopy or with echelle spectrometers for very broad-band coverage. EDI's heterodyning technique enhances the spectrometer's response to high spectral-density features, increasing the effective resolution by factors of several while retaining its bandwidth. The method is extremely robust to instrumental insults such as focal spot size or displacement. The EDI uses no moving parts, such as purely interferometric FTS spectrometers, and can cover a much wider simultaneous bandpass than other internally dispersed interferometers (e.g. HHS or SHS).

  15. The EarthCARE broadband radiometer detectors

    NASA Astrophysics Data System (ADS)

    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 single-molecule excitation spectroscopy

    NASA Astrophysics Data System (ADS)

    Piatkowski, Lukasz; Gellings, Esther; van Hulst, Niek F.

    2016-01-01

    Over the past 25 years, single-molecule spectroscopy has developed into a widely used tool in multiple disciplines of science. The diversity of routinely recorded emission spectra does underpin the strength of the single-molecule approach in resolving the heterogeneity and dynamics, otherwise hidden in the ensemble. In early cryogenic studies single molecules were identified by their distinct excitation spectra, yet measuring excitation spectra at room temperature remains challenging. Here we present a broadband Fourier approach that allows rapid recording of excitation spectra of individual molecules under ambient conditions and that is robust against blinking and bleaching. Applying the method we show that the excitation spectra of individual molecules exhibit an extreme distribution of solvatochromic shifts and distinct spectral shapes. Importantly, we demonstrate that the sensitivity and speed of the broadband technique is comparable to that of emission spectroscopy putting both techniques side-by-side in single-molecule spectroscopy.

  17. A broad-band scalar vortex coronagraph

    NASA Astrophysics Data System (ADS)

    Errmann, R.; Minardi, S.; Pertsch, T.

    2013-10-01

    Broad-band coronagraphy with deep nulling and small inner working angle has the potential of delivering images and spectra of exoplanets and other faint objects. In recent years, many coronagraphic schemes have been proposed, the most promising being the optical vortex phase mask coronagraphs. In this paper, a new scheme of broad-band optical scalar vortex coronagraph is proposed and characterized experimentally in the laboratory. Our setup employs a pair of computer-generated phase gratings (one of them containing a singularity) to control the chromatic dispersion of phase plates and achieves a constant peak-to-peak attenuation below 1 × 10-3 over a bandwidth of 120 nm centred at 700 nm. An inner working angle of ˜λ/D is demonstrated along with a raw contrast of 11.5 mag at 2λ/D.

  18. Broadband Visible Light Induced NO Formation

    SciTech Connect

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

    2009-06-19

    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.

  19. Broadband Phase Spectroscopy over Turbulent Air Paths

    NASA Astrophysics Data System (ADS)

    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 CO2 , CH4 , and H2O 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 CO2 . While conventional broadband spectroscopy only measures intensity absorption, this approach enables measurement of the full complex susceptibility even in practical open path sensing.

  20. 4-GHz high-efficiency broadband FET power amplifiers

    NASA Astrophysics Data System (ADS)

    Chou, S.; Chang, C.

    1982-11-01

    The development and performance of a 4-GHz high-efficiency broadband FET power amplifier module for use in communications satellite transponders is discussed. The design, which is based on the parameters of a commercially available 7.2-mm multicell FET device, was optimized by the use of a CAD program, with broader bandwidth achieved by the addition of two open stubs to the input matching circuit. Six single-ended amplifier modules have been fabricated, tuned and tested, two being high-gain, 17.5% bandwidth designs and four being lower-gain, 25% bandwidth designs. The higher-gain modules, with a 0.5-dB bandwidth of 700 MHz (3.6 to 4.3 GHz) show a 6-dB gain and 3.23-W output power at the maximum efficiency of 48.6%, while broadband modules (0.5-dB bandwidth 900 MHz) deliver 5-W RF power at the maximum efficiency of 36%. The high-performance amplifiers may thus be used in satellite solid-state power amplifiers as replacements for traveling wave tubes.

  1. Broad-band UHF dipole array

    NASA Technical Reports Server (NTRS)

    Bailey, M. C.

    1985-01-01

    A 6X6 array of fan-dipoles was designed to operate in the 510 to 660 MHz frequency range for aircraft flight test and evaluation of a UHF radiometer system. A broad-band dipole design operating near the first resonance is detailed. Measured VSWR and radiation patterns for the dipole array demonstrate achievable bandwidths in the 35 percent to 40 percent range.

  2. BROADBAND EXCITATION IN NUCLEAR MAGNETIC RESONANCE

    SciTech Connect

    Tycko, R.

    1984-10-01

    Theoretical methods for designing sequences of radio frequency (rf) radiation pulses for broadband excitation of spin systems in nuclear magnetic resonance (NMR) are described. The sequences excite spins uniformly over large ranges of resonant frequencies arising from static magnetic field inhomogeneity, chemical shift differences, or spin couplings, or over large ranges of rf field amplitudes. Specific sequences for creating a population inversion or transverse magnetization are derived and demonstrated experimentally in liquid and solid state NMR. One approach to broadband excitation is based on principles of coherent averaging theory. A general formalism for deriving pulse sequences is given, along with computational methods for specific cases. This approach leads to sequences that produce strictly constant transformations of a spin system. The importance of this feature in NMR applications is discussed. A second approach to broadband excitation makes use of iterative schemes, i.e. sets of operations that are applied repetitively to a given initial pulse sequences, generating a series of increasingly complex sequences with increasingly desirable properties. A general mathematical framework for analyzing iterative schemes is developed. An iterative scheme is treated as a function that acts on a space of operators corresponding to the transformations produced by all possible pulse sequences. The fixed points of the function and the stability of the fixed points are shown to determine the essential behavior of the scheme. Iterative schemes for broadband population inversion are treated in detail. Algebraic and numerical methods for performing the mathematical analysis are presented. Two additional topics are treated. The first is the construction of sequences for uniform excitation of double-quantum coherence and for uniform polarization transfer over a range of spin couplings. Double-quantum excitation sequences are demonstrated in a liquid crystal system. The

  3. Data quality control of ADSN Broadband stations

    NASA Astrophysics Data System (ADS)

    Alili, Azouaou; Yelles-chaouche, Abd el karim; Allili, Toufik; Messemen, Walid

    2014-05-01

    In this work we present the analysis of continuous waveform of the Algerian digital seismic network recorded during five years from 2008 to 2013 for twenty broadband stations using the power spectral densities (PSDs) and their corresponding probability density functions (PDFs) algorithm of McNamara, and Buland (2004). ADSN Broadband stations data quality is one main concern and interest of ADSN technical team. Indeed, the quality of the data from broadband stations is continuously controlled in quasi-realtime using "PQLX" (Pascal Quick Look eXtended) software to compute the PDFs and PSDs during the operation of the stations at different frequency range. At each station the level of noise is shown, which we can see diurnal and seasonal variation. From the data analysis, most of the ADSN Broadband stations display good records in the several frequency domains in relation with their site installation. However some of stations near the urban areas could present some noisy disturbances. This led sometimes to generate some ghost events. In the low frequency, some stations could be still influenced by the temperature variations. This long period of records from 2008 to 2013, led us to analyze and control the several stations year by year taking into account the seasons and to know about their work during five years. This analysis is also very important to improve in the future quality of station installation and choose the optimal station design in aim to reduce cultural noise and large fluctuation of temperature and pressure. Key words: PQLX, PDFs, PSDs, Broad Band

  4. Broadband Hybrid Holographic Multiplexing with Geometric Metasurfaces.

    PubMed

    Huang, Lingling; Mühlenbernd, Holger; Li, Xiaowei; Song, Xu; Bai, Benfeng; Wang, Yongtian; Zentgraf, Thomas

    2015-11-01

    An effective way for broadband holographic multiplexing based on geometric metasurfaces is demonstrated by the integration of several recording channels into a single device. Each image can be individually addressed with a unique set of parameters, such as circular polarization, position, and angle. Such a technique paves the way for a wide range of applications related to optical patterning, encryption, and information processing. PMID:26398589

  5. Design of broadband single polarized antenna

    NASA Astrophysics Data System (ADS)

    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.

  6. HCIT Broadband Contrast Performance Sensitivity Studies

    NASA Technical Reports Server (NTRS)

    Sidick, Erkin; Shaklan, Stuart; Balasubramanian, Kunjithapatham

    2012-01-01

    One of the important milestones of the TPF Coronagraph project is to demonstrate the ability to predict the performance sensitivities of the system at levels consistent with exo-planet detection requirement. We want to gain some general understanding about the potentials and the limitations of the current single-Deformable-Mirror (DM) High-contrast imaging testbed (HCIT) system through modeling and simulations. Specifically, we want to understand the effects of some common errors on the EFC-based control of e-field over a half dark-hole region and broadband contrast. Investigated errors include: (1) Absorbing particles on a flat-mirror (2) Defects on the Occulter surface (3) Dead actuators on the DM. We also investigated the effects of control bandwidth on the broadband contrast. We used a MACOS-based simulation algorithm which (1) combines a ray trace, diffraction model, & a broadband wavefront control algorithm (2) is capable of performing full three-dimensional near-field diffraction analysis

  7. CFD Computation of Broadband Fan Interaction Noise

    NASA Technical Reports Server (NTRS)

    Grace, Sheryl M.; Sondak, Douglas L.; Dorney, Daniel J.

    2007-01-01

    In this study, a 3-D, unsteady, Reynolds Averaged Navier Stokes CFD code coupled to an acoustic calculation is used to predict the contribution of the exit guide vanes to broadband fan noise. The configuration investigated is that corresponding to the NASA Source Diagnostic Test (SDT) 22-in fan rig. Then an acoustic model introduced by Nallasamy which is based on 2-D strip theory is used to compute the broadband rotor-stator interaction noise. One configuration from the SDT matrix is considered here: the fan speed correlating to approach, and outlet guide vane count designed for cut-off of the blade passage frequency. Thus, in the chosen configuration, there are 22 rotor blades and 54 stator blades. The stators are located 2.5 tip chords downstream of the rotor trailing edge. The RANS computations are used to obtain the spectra of the unsteady surface pressure on the exit guide vanes. This surface pressure is then integrated together with the Green's function for and infinite cylindrical duct to obtain the acoustic field. The results from this investigation validate the use of the CFD code along with the acoustic model for broadband fan noise predictions. The validation enables future investigations such as the determination of rotor tip clearance and stator solidity effects on fan rotor-stator interaction noise.

  8. Broadband quasi-optical SIS mixers with large area junctions

    NASA Astrophysics Data System (ADS)

    Pance, Gordana; Wengler, Micheal J.

    1994-04-01

    A broadband quasi-optical superconducting tunnel junction (SIS) mixer with integrated tuning elements was designed and tested. We are able to achieve very low noise performance using commercially available niobium integrated circuit (IC) technology. The low critical current density (980 A/sq cm) and large area (12 sq micron) of the commercial SIS's is compensated by the ability to fabricate accurate integrated tuning structures in the mature niobium IC process available from Hypres, Inc. Noise measurements were made in the frequency range from 70 to 105 GHz. The best uncorrected double sideband receiver noise is 38 K at 77 GHz, with receiver noise temperatures less than 100 K from 75 to 102 GHz.

  9. Tunable Dielectric Materials and Devices for Broadband Wireless Communications

    NASA Technical Reports Server (NTRS)

    Mueller, Carl H.; Miranda, Felix A.; Dayton, James A. (Technical Monitor)

    1998-01-01

    Wireless and satellite communications are a rapidly growing industries which are slated for explosive growth into emerging countries as well as countries with advanced economies. The dominant trend in wireless communication systems is towards broadband applications such as multimedia file transfer, video transmission and Internet access. These applications require much higher data transmission rates than those currently used for voice transmission applications. To achieve these higher data rates, substantially larger bandwidths and higher carrier frequencies are required. A key roadblock to implementing these systems at K-band (18-26.5 GHz) and Ka-band (26.5-40 GHz) is the need to develop hardware which meets the requirements for high data rate transmission in a cost effective manner. In this chapter, we report on the status of tunable dielectric thin films for devices, such as resonators, filters, phased array antennas, and tunable oscillators, which utilize nonlinear tuning in the control elements. Paraelectric materials such as Barium Strontium Titanate ((Ba, Sr)TiO3) have dielectric constants which can be tuned by varying the magnitude of the electric field across the material. Therefore, these materials can be used to control the frequency and/or phase response of various devices such as electronically steerable phased array antennas, oscillators, and filters. Currently, tunable dielectric devices are being developed for applications which require high tunability, low loss, and good RF power-handling capabilities at microwave and millimeter-wave frequencies. These properties are strongly impacted by film microstructure and device design, and considerable developmental work is still required. However, in the last several years enormous progress has occurred in this field, validating the potential of tunable dielectric technology for broadband wireless communication applications. In this chapter we summarize how film processing techniques, microwave test

  10. Model rotor low frequency broadband noise at moderate tip speeds

    NASA Technical Reports Server (NTRS)

    Humbad, N. G.; Harris, W. L.

    1980-01-01

    The results of an experimental investigation of low frequency broadband noise (LFBN) radiated from model helicopter rotors are presented. The results are for a range of tip Mach numbers (Mt) up to 0.50. The effect of rotor blade loading, advance ratio, tip speed, number of blades and free stream turbulence on the sound pressure level (SPL) and the spectrum of LFBN have been investigated. The peak SPL of LFBN appears to follow an M(4) law if the effect of rms turbulence velocity is removed. The peak SPL of LFBN seems to saturate with increases in advance ratio and with blade loading, and is proportional to the square of the turbulence integral scale when the effect of rms turbulence velocity and Mt are removed. Also, a simple peak SPL scaling law for noise from a helicopter rotor in forward flight due to convected sinusoidal gust is developed. The trend predicted by this scaling law is found to be satisfactory for the variation of the peak SPL of LFBN with tip speed.

  11. Advanced imaging research and development at DARPA

    NASA Astrophysics Data System (ADS)

    Dhar, Nibir K.; Dat, Ravi

    2012-06-01

    Advances in imaging technology have huge impact on our daily lives. Innovations in optics, focal plane arrays (FPA), microelectronics and computation have revolutionized camera design. As a result, new approaches to camera design and low cost manufacturing is now possible. These advances are clearly evident in visible wavelength band due to pixel scaling, improvements in silicon material and CMOS technology. CMOS cameras are available in cell phones and many other consumer products. Advances in infrared imaging technology have been slow due to market volume and many technological barriers in detector materials, optics and fundamental limits imposed by the scaling laws of optics. There is of course much room for improvements in both, visible and infrared imaging technology. This paper highlights various technology development projects at DARPA to advance the imaging technology for both, visible and infrared. Challenges and potentials solutions are highlighted in areas related to wide field-of-view camera design, small pitch pixel, broadband and multiband detectors and focal plane arrays.

  12. Locating and Quantifying Broadband Fan Sources Using In-Duct Microphones

    NASA Technical Reports Server (NTRS)

    Dougherty, Robert P.; Walker, Bruce E.; Sutliff, Daniel L.

    2010-01-01

    In-duct beamforming techniques have been developed for locating broadband noise sources on a low-speed fan and quantifying the acoustic power in the inlet and aft fan ducts. The NASA Glenn Research Center's Advanced Noise Control Fan was used as a test bed. Several of the blades were modified to provide a broadband source to evaluate the efficacy of the in-duct beamforming technique. Phased arrays consisting of rings and line arrays of microphones were employed. For the imaging, the data were mathematically resampled in the frame of reference of the rotating fan. For both the imaging and power measurement steps, array steering vectors were computed using annular duct modal expansions, selected subsets of the cross spectral matrix elements were used, and the DAMAS and CLEAN-SC deconvolution algorithms were applied.

  13. New UV instrumentation enabled by enhanced broadband reflectivity lithium fluoride coatings

    NASA Astrophysics Data System (ADS)

    Fleming, Brian T.; Quijada, Manuel A.; France, Kevin; Hoadley, Keri; Del Hoyo, Javier; Kruczek, Nicholas

    2015-08-01

    We present the results of a preliminary aging study of new enhanced broadband reflectivity lithium fluoride mirror coatings under development at the thin films laboratory at GSFC. These coatings have demonstrated greater than 80% reflectivity from the Lyman ultraviolet (~1020 Å) to the optical, and have the potential to revolutionize far-ultraviolet instrument design and capabilities. This work is part of a concept study in preparation for the fight qualification of these new coatings in a working astronomical environment. We outline the goals for TRL advancement, and discuss the instrument capabilities enabled by these high reflectivity broadband coatings on potential future space missions. We also present the early design of the first space experiment to utilize these coatings, the proposed University of Colorado sounding rocket payload SISTINE, and show how these new coatings make the science goals of SISTINE attainable on a suborbital platform.

  14. Near real-time noise removal for the Monterey Ocean Bottom Broadband (MOBB) seismic station data

    NASA Astrophysics Data System (ADS)

    Guinois, M.; Zheng, Z.; Taira, T.; Romanowicz, B. A.

    2012-12-01

    The Monterey Ocean Bottom Broadband (MOBB) observatory, located 40 km offshore central California, at a water depth of 1000 m, provides important complementary coverage of the San Andreas Fualt system to the land-based network. First installed in 2002, it is arguably the longest lived ocean bottom broadband seismic station. It includes a three-component broadband Guralp CMG-1T seismometer and a collocated differential pressure gauge (DPG) to measure the local water pressure continuously, as well as a current meter. After 7 years of autonomous operation, in February 2009, MOBB was successfully connected to the MARS cable (http://www.mbari.org/mars), and the data have been available in real time at the Northern California Earthquake Data Center (Romanowicz et al., 2009). However, the usage of MOBB data has been limited because of the noisy character of the data, in particular at periods of interest for regional moment tensor studies (20-100 sec), due to the ocean infragravity waves. Crawford and Webb (2000) demonstrated that there is a strong correlation between the water pressure and the vertical component of seafloor ground velocity in the infragravity wave band. Applying this to MOBB vertical component data, a transfer function (TF) was determined and utilized to successfully deconvolve the pressure-correlated noise from the vertical component of MOBB seismograms (Dolenc et al., 2007) in the period band 20-200 sec. Romanowicz et al. (2003, 2009) presented examples of how the cleaned MOBB data contribute to the determination of source parameters and regional structure. These past efforts, however, have been mostly case studies for illustration purpose. In this study, we systematically process all the available MOBB data since 2009 (because the cable was trawled, about a year of data is missing from February 2010 to June 2011). We calculate the TF over time and find that it is generally very stable, except for one change in 2010 due to an instrument replacement. Two

  15. Observed Relationship Between Ion Energization and the Broadband ELF Spectrum

    NASA Technical Reports Server (NTRS)

    Coffey, V. N.; Chandler, M. O.; Singh, N.; Moore, T. E.

    2004-01-01

    Many existing theories linking broadband ELF wave activity (BBELF) to ion energization and outflow are based on the gyro-resonant heating of ions. Recent studies on the properties of these broadband waves show that other mechanisms may be more relevant. Using data from the Polar satellite, we will present an analysis of the observed relationship between the broadband electric field spectrum and ion energization across the cusp, auroral oval, and polar cap.

  16. Calculated secondary yields for proton broadband using DECAY TURTLE

    SciTech Connect

    Sondgeroth, A.

    1995-02-01

    The calculations for the yields were done by Al Sondgeroth and Anthony Malensek. The authors used the DECAY deck called PBSEC{_}E.DAT from the CMS DECKS library. After obtaining the run modes and calibration modes from the liaison physicist, they made individual decay runs, using DECAY TURTLE from the CMS libraries and a production spectrum subroutine which was modified by Anthony, for each particle and decay mode for all particle types coming out of the target box. Results were weighted according to branching ratios for particles with more than one decay mode. The production spectra were produced assuming beryllium as the target. The optional deuterium target available to broadband will produce slightly higher yields. It should be noted that they did not include pion yields from klong decays because they could not simulate three body decays. Pions from klongs would add a very small fraction to the total yield.

  17. Broad-band acoustic Doppler current profiler

    USGS Publications Warehouse

    Cobb, E.D.

    1993-01-01

    The broad-band acoustic Doppler current profiler is an instrument that determines velocity based on the Doppler principle by reflecting acoustic signals off sediment particles in the water. The instrument is capable of measuring velocity magnitude and direction throughout a water column and of measuring water depth. It is also capable of bottom tracking and can, therefore, keep track of its own relative position as it is moved across a channel. Discharge measurements can be made quickly and, based on limited tests, accurately with this instrument. ?? 1993.

  18. The RINGS Survey: Optical Broadband Photometry

    NASA Astrophysics Data System (ADS)

    Kuzio de Naray, Rachel; Mitchell, Carl; Spekkens, Kristine; Sellwood, Jerry; Williams, Ted

    2016-01-01

    We have targeted a sample of 19 nearby spiral galaxies, the RSS Imaging and Spectroscopy Nearby Galaxy Survey (RINGS), for detailed study of their mass distributions. We have obtained Fabry-Perot Halpha velocity fields using the Southern African Large Telescope (SALT), 21-cm HI observations using the Very Large Array (VLA), and optical broadband BVRI photometry using the CTIO 0.9m and KPNO 2.1m telescopes. We present the results of the photometric component of the survey including multicolor images, surface brightness profiles, and DiskFit structural models.

  19. A novel broadband waterborne acoustic absorber

    NASA Astrophysics Data System (ADS)

    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.

  20. Progress in rotor broadband noise research

    NASA Technical Reports Server (NTRS)

    Brooks, T. F.; Schlinker, R. H.

    1983-01-01

    The current status of research on various rotor broadband noise sources is reviewed. Theoretical modeling techniques which appear to have the most promise in the development of successful noise prediction capabilities are emphasized. The types of noise considered include: turbulence ingestion noise, blade self-noise due to turbulence passing the trailing edge, blade self-noise due to separated flow, and blade self-noise due to vortex shedding. Comparisons with experimental results are given, and present theoretical and experimental limitations are delineated to help identify areas of needed research.

  1. Broadband Planar 5:1 Impedence Transformer

    NASA Technical Reports Server (NTRS)

    Ehsan, Negar; Hsieh, Wen-Ting; Moseley, Samuel H.; Wollack, Edward J.

    2015-01-01

    This paper presents a broadband Guanella-type planar impedance transformer that transforms so 50 omega to 10 omega with a 10 dB bandwidth of 1-14GHz. The transformer is designed on a flexible 50 micrometer thick polyimide substrate in microstrip and parallel-plate transmission line topologies, and is Inspired by the traditional 4:1 Guanella transformer. Back-to-back transformers were designed and fabricated for characterization in a 50 omega system. Simulated and measured results are in excellent agreement.

  2. Broadband rotary joint for high speed ultrahigh resolution endoscopic OCT imaging (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Alemohammad, Milad; Yuan, Wu; Mavadia-Shukla, Jessica; Liang, Wenxuan; Yu, Xiaoyun; Yu, Shaoyong; Li, Xingde

    2016-03-01

    Endoscopic OCT is a promising technology enabling noninvasive in vivo imaging of internal organs, such as the gastrointestinal tract and airways. The past few years have witnessed continued efforts to achieve ultrahigh resolution and speed. It is well-known that the axial resolution in OCT imaging has a quadratic dependence on the central wavelength. While conventional OCT endoscopes operate in 1300 nm wavelength, the second-generation endoscopes are designed for operation around 800 nm where turn-key, broadband sources are becoming readily available. Traditionally 1300 nm OCT endoscopes are scanned at the proximal end, and a broadband fiber-optic rotary joint as a key component in scanning endoscopic OCT is commercially available. Bandwidths in commercial 800 nm rotary joints are unfortunately compromised due to severe chromatic aberration, which limits the resolution afforded by the broadband light source. In the past we remedied this limitation by using a home-made capillary-tube-based rotary joint where the maximum reliable speed is ~10 revolutions/second. In this submission we report our second-generation, home-built high-speed and broadband rotary joint for 800 nm wavelength, which uses achromatic doublets in order achieve broadband achromatic operation. The measured one-way throughput of the rotary joint is >67 % while the fluctuation of the double-pass coupling efficiency during 360° rotation is less than +/-5 % at a speed of 70 revolutions/second. We demonstrate the operation of this rotary joint in conjunction with our ultrahigh-resolution (2.4 µm in air) diffractive catheter by three-dimensional full-circumferential endoscopic imaging of guinea pig esophagus at 70 frames per second in vivo.

  3. Simulation and Implementation of Moth-eye Structures as a Broadband Anti-Reflective Layer

    NASA Astrophysics Data System (ADS)

    Deshpande, Ketan S.

    Conventional single layer thin anti-reflective coatings (ARCs) are only suitable for narrowband applications. A multilayer film stack is often employed for broadband applications. A coating of multiple layers with alternating low and high refractive index materials increases the overall cost of the system. This makes multilayer ARCs unsuitable for low-cost broadband applications. Since the discovery of moth-eye corneal nipple patterns and their potential applicability in the field of broadband ARCs, many studies have been carried out to fabricate these bio-inspired nanostructures with available manufacturing processes. Plasma etching processes used in microelectronic manufacturing are applied for creating these nanostructures at the Rochester Institute of Technology's Semiconductor & Microsystems Fabrication Laboratory (SMFL). Atomic Force Microscope (AFM) scanned surfaces of the nanostructure layer are simulated and characterized for their optical properties using a Finite-Difference Time Domain (FDTD) simulator from Lumerical Solutions, Inc. known as FDTD Solutions. Simulation results show that the layer is anti-reflective over 50 to 350 nm broadband of wavelengths at 0° angle of incidence. These simulation results were supported by ellipsometer reflection measurements off the actual samples at multiple angles of light incidence, which show a 10% to 15% decrease in reflection for 240 to 400 nm wavelengths. Further improvements in the optical efficiency of these structures can be achieved through simulation-fabrication-characterization cycles performed for this project. The optimized nanostructures can then serve the purpose of low-cost anti-reflective coatings for solar cells and similar applications.

  4. Broadband Processing in a Noisy Shallow Ocean Environment: A Particle Filtering Approach

    DOE PAGESBeta

    Candy, J. V.

    2016-04-14

    Here we report that when a broadband source propagates sound in a shallow ocean the received data can become quite complicated due to temperature-related sound-speed variations and therefore a highly dispersive environment. Noise and uncertainties disrupt this already chaotic environment even further because disturbances propagate through the same inherent acoustic channel. The broadband (signal) estimation/detection problem can be decomposed into a set of narrowband solutions that are processed separately and then combined to achieve more enhancement of signal levels than that available from a single frequency, thereby allowing more information to be extracted leading to a more reliable source detection.more » A Bayesian solution to the broadband modal function tracking, pressure-field enhancement, and source detection problem is developed that leads to nonparametric estimates of desired posterior distributions enabling the estimation of useful statistics and an improved processor/detector. In conclusion, to investigate the processor capabilities, we synthesize an ensemble of noisy, broadband, shallow-ocean measurements to evaluate its overall performance using an information theoretical metric for the preprocessor and the receiver operating characteristic curve for the detector.« less

  5. BROADBAND PHOTOMETRIC REVERBERATION MAPPING OF NGC 4395

    SciTech Connect

    Edri, Haim; Rafter, Stephen E.; Kaspi, Shai; Behar, Ehud; Chelouche, Doron E-mail: shai@physics.technion.ac.il E-mail: doron@sci.haifa.ac.il

    2012-09-01

    We present results of broadband photometric reverberation mapping (RM) to measure the radius of the broad-line region, and subsequently the black hole mass (M{sub BH}), in the nearby, low-luminosity active galactic nuclei NGC 4395. Using the Wise Observatory's 1 m telescope equipped with the Sloan Digital Sky Survey g', r', and i' broadband filters, we monitored NGC 4395 for nine consecutive nights and obtained three light curves each with over 250 data points. The g' and r' bands include time variable contributions from H{beta} and H{alpha}, respectively, plus continuum. The i' band is free of broad lines and covers exclusively continuum. We show that by looking for a peak in the difference between the cross-correlation and the auto-correlation functions for all combinations of filters, we can get a reliable estimate of the time lag necessary to compute M{sub BH}. We measure the time lag for H{alpha} to be 3.6 {+-} 0.8 hr, comparable to previous studies using the line-resolved spectroscopic RM method. We argue that this lag implies a black hole mass of M{sub BH} = (4.9 {+-} 2.6) Multiplication-Sign 10{sup 4} M{sub Sun }.

  6. Broadband acoustic properties of a murine skull

    NASA Astrophysics Data System (ADS)

    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.

  7. Inverse Doppler Effects in Broadband Acoustic Metamaterials

    PubMed Central

    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

  8. Reflective afocal broadband adaptive optics scanning ophthalmoscope.

    PubMed

    Dubra, Alfredo; Sulai, Yusufu

    2011-06-01

    A broadband adaptive optics scanning ophthalmoscope (BAOSO) consisting of four afocal telescopes, formed by pairs of off-axis spherical mirrors in a non-planar arrangement, is presented. The non-planar folding of the telescopes is used to simultaneously reduce pupil and image plane astigmatism. The former improves the adaptive optics performance by reducing the root-mean-square (RMS) of the wavefront and the beam wandering due to optical scanning. The latter provides diffraction limited performance over a 3 diopter (D) vergence range. This vergence range allows for the use of any broadband light source(s) in the 450-850 nm wavelength range to simultaneously image any combination of retinal layers. Imaging modalities that could benefit from such a large vergence range are optical coherence tomography (OCT), multi- and hyper-spectral imaging, single- and multi-photon fluorescence. The benefits of the non-planar telescopes in the BAOSO are illustrated by resolving the human foveal photoreceptor mosaic in reflectance using two different superluminescent diodes with 680 and 796 nm peak wavelengths, reaching the eye with a vergence of 0.76 D relative to each other. PMID:21698035

  9. Reflective afocal broadband adaptive optics scanning ophthalmoscope

    PubMed Central

    Dubra, Alfredo; Sulai, Yusufu

    2011-01-01

    A broadband adaptive optics scanning ophthalmoscope (BAOSO) consisting of four afocal telescopes, formed by pairs of off-axis spherical mirrors in a non-planar arrangement, is presented. The non-planar folding of the telescopes is used to simultaneously reduce pupil and image plane astigmatism. The former improves the adaptive optics performance by reducing the root-mean-square (RMS) of the wavefront and the beam wandering due to optical scanning. The latter provides diffraction limited performance over a 3 diopter (D) vergence range. This vergence range allows for the use of any broadband light source(s) in the 450-850 nm wavelength range to simultaneously image any combination of retinal layers. Imaging modalities that could benefit from such a large vergence range are optical coherence tomography (OCT), multi- and hyper-spectral imaging, single- and multi-photon fluorescence. The benefits of the non-planar telescopes in the BAOSO are illustrated by resolving the human foveal photoreceptor mosaic in reflectance using two different superluminescent diodes with 680 and 796 nm peak wavelengths, reaching the eye with a vergence of 0.76 D relative to each other. PMID:21698035

  10. Cascaded frequency doublers for broadband laser radiation

    SciTech Connect

    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)

  11. Cascaded frequency doublers for broadband laser radiation

    NASA Astrophysics Data System (ADS)

    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 %.

  12. A novel broadband circularly polarised monopole antenna

    NASA Astrophysics Data System (ADS)

    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.

  13. Evaluation of Arctic Broadband Surface Radiation Measurements

    SciTech Connect

    Matsui, N.; Long, Charles N.; Augustine, J. A.; Halliwell, D.; Uttal, Taneil; Longenecker, D.; Niebergale, J.; Wendell, J.; Albee, R.

    2012-02-24

    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 mounted on complex mechanical platforms (solar trackers) that rotate sensors and shading devices that track the sun. High quality measurements require striking a balance between locating sensors in a pristine undisturbed location free of artificial blockage (such as buildings and towers) and providing accessibility to allow operators to clean and maintain the instruments. Three significant sources of erroneous data include solar tracker malfunctions, rime/frost/snow deposition on the instruments and operational problems due to limited operator access in extreme weather conditions. In this study, a comparison is made between the global and component sum (direct [vertical component] + diffuse) shortwave measurements. The difference between these two quantities (that theoretically should be zero) is used to illustrate the magnitude and seasonality of radiation flux measurement problems. The problem of rime/frost/snow deposition is investigated in more detail for one case study utilizing both shortwave and longwave measurements. Solutions to these operational problems are proposed that utilize measurement redundancy, more sophisticated heating and ventilation strategies and a more systematic program of operational support and subsequent data quality protocols.

  14. Evaluation of arctic broadband surface radiation measurements

    NASA Astrophysics Data System (ADS)

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

    2011-08-01

    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 mounted on complex mechanical platforms (solar trackers) that rotate sensors and shading devices that track the sun. High quality measurements require striking a balance between locating sensors in a pristine undisturbed location free of artificial blockage (such as buildings and towers) and providing accessibility to allow operators to clean and maintain the instruments. Three significant sources of erroneous data include solar tracker malfunctions, rime/frost/snow deposition on the instruments and operational problems due to limited operator access in extreme weather conditions. In this study, a comparison is made between the global and component sum (direct [vertical component] + diffuse) shortwave measurements. The difference between these two quantities (that theoretically should be zero) is used to illustrate the magnitude and seasonality of radiation flux measurement problems. The problem of rime/frost/snow deposition is investigated in more detail for one case study utilizing both shortwave and longwave measurements. Solutions to these operational problems are proposed that utilize measurement redundancy, more sophisticated heating and ventilation strategies and a more systematic program of operational support and subsequent data quality protocols.

  15. Municipal Broadband in Wilson, North Carolina: A Study

    ERIC Educational Resources Information Center

    O'Boyle, Timothy

    2012-01-01

    Relatively little empirical attention has been paid to the political economy of publicly-retailed fiber-optic broadband internet service. To address this gap in the literature, this dissertation examines the history, dynamics and trends in the municipal broadband movement. In specific, Wilson, North Carolina's Greenlight service is examined…

  16. Broadband linear and nonlinear optical response of plasmonic quasicrystals

    NASA Astrophysics Data System (ADS)

    Ravishankar, Ajith P.; Yallapragada, V. J.; Kasture, S.; Nagarajan, Arvind; Achanta, Venu Gopal

    2016-05-01

    Plasmonic quasicrystals with 5-fold rotation symmetry are shown to offer broadband transmission enhancement. The observed linear transmission enhancement leads to broadband second harmonic generation in a wide incident angle range contrary to unpatterned gold film. From the measured linear and harmonic transmitted powers, we estimate the 2nd order susceptibility values in the 760-840 nm range.

  17. Implementation of a Broadband Cable System on a University Campus.

    ERIC Educational Resources Information Center

    Rhoadarmer, Michael

    1995-01-01

    Discusses broadband communications; broadband coaxial cable and its utility in the media center; basic electronics of radio signals (radio frequency, radio band, bandwidth, MHz, skimming, decibels, sloped amplifiers); engineering basics (insertion loss, splitter, tap, and three beats); and factors to consider before designing a campus broadband…

  18. Silicon graphene waveguide tunable broadband microwave photonics phase shifter.

    PubMed

    Capmany, José; Domenech, David; Muñoz, Pascual

    2014-04-01

    We propose the use of silicon graphene waveguides to implement a tunable broadband microwave photonics phase shifter based on integrated ring cavities. Numerical computation results show the feasibility for broadband operation over 40 GHz bandwidth and full 360° radiofrequency phase-shift with a modest voltage excursion of 0.12 volt. PMID:24718185

  19. 78 FR 8353 - Rural Broadband Access Loans and Loan Guarantees

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-06

    ... referred to as the Agency, is adopting as final, with change, an interim rule (published at 76 FR 13770 on... percent) with in-home Internet access had a broadband connection. A marked difference exists, however, between urban and rural broadband use--only 70 percent of rural households with in-home Internet...

  20. Boeing 18-Inch Fan Rig Broadband Noise Test

    NASA Technical Reports Server (NTRS)

    Ganz, Ulrich W.; Joppa, Paul D.; Patten, Timothy J.; Scharpf, Daniel F.

    1998-01-01

    The purposes of the subject test were to identify and quantify the mechanisms by which fan broadband noise is produced, and to assess the validity of such theoretical models of those mechanisms as may be available. The test was conducted with the Boeing 18-inch fan rig in the Boeing Low-Speed Aeroacoustic Facility (LSAF). The rig was designed to be particularly clean and geometrically simple to facilitate theoretical modeling and to minimize sources of interfering noise. The inlet is cylindrical and is equipped with a boundary layer suction system. The fan is typical of modern high-by-pass ratio designs but is capable of operating with or without fan exit guide vanes (stators), and there is only a single flow stream. Fan loading and tip clearance are adjustable. Instrumentation included measurements of fan performance, the unsteady flow field incident on the fan and stators, and far-field and in-duct acoustic fields. The acoustic results were manipulated to estimate the noise generated by different sources. Significant fan broadband noise was found to come from the rotor self-noise as measured with clean inflow and no boundary layer. The rotor tip clearance affected rotor self-noise somewhat. The interaction of the rotor with inlet boundary layer turbulence is also a significant source, and is strongly affected by rotor tip clearance. High level noise can be generated by a high-order nonuniform rotating at a fraction of the fan speed, at least when tip clearance and loading are both large. Stator-generated noise is the loudest of the significant sources, by a small margin, at least on this rig. Stator noise is significantly affected by propagation through the fan.

  1. Automatically acquired broadband plasmonic-metamaterial black absorber during the metallic film-formation.

    PubMed

    Liu, Zhengqi; Liu, Xiaoshan; Huang, Shan; Pan, Pingping; Chen, Jing; Liu, Guiqiang; Gu, Gang

    2015-03-01

    Broadband electromagnetic wave absorbers are highly desirable in numerous applications such as solar-energy harvesting, thermo-photovoltaics, and photon detection. The aim to efficiently achieve ultrathin broadband absorbers with high-yield and low-cost fabrication process has long been pursued. Here, we theoretically propose and experimentally demonstrate a unique broadband plasmonic-metamaterial absorber by utilizing a sub-10 nm meta-surface film structure to replace the precisely designed metamaterial crystal in the common metal-dielectric-metal absorbers. The unique ultrathin meta-surface can be automatically obtained during the metal film formation process. Spectral bandwidth with absorbance above 80% is up to 396 nm, where the full absorption width at half-maximum is about 92%. The average value of absorbance across the whole spectral range of 370-880 nm reaches 83%. These super absorption properties can be attributed to the particle plasmon resonances and plasmon near-field coupling by the automatically formed metallic nanoparticles as well as the plasmon polaritons of the metal film with the induced plasmonic magnetic resonances occurring between the top meta-surface and the bottom metal mirror. This method is quite simple, cost-effective for large-area fabrication, and compatible with current industrial methods for microelectro-mechanical systems, which makes it an outstanding candidate for advanced high-efficiency absorber materials. PMID:25679790

  2. Rapid-Response Low Infrared Emission Broadband Ultrathin Plasmonic Light Absorber

    PubMed Central

    Tagliabue, Giulia; Eghlidi, Hadi; Poulikakos, Dimos

    2014-01-01

    Plasmonic nanostructures can significantly advance broadband visible-light absorption, with absorber thicknesses in the sub-wavelength regime, much thinner than conventional broadband coatings. Such absorbers have inherently very small heat capacity, hence a very rapid response time, and high light power-to-temperature sensitivity. Additionally, their surface emissivity can be spectrally tuned to suppress infrared thermal radiation. These capabilities make plasmonic absorbers promising candidates for fast light-to-heat applications, such as radiation sensors. Here we investigate the light-to-heat conversion properties of a metal-insulator-metal broadband plasmonic absorber, fabricated as a free-standing membrane. Using a fast IR camera, we show that the transient response of the absorber has a characteristic time below 13 ms, nearly one order of magnitude lower than a similar membrane coated with a commercial black spray. Concurrently, despite the small thickness, due to the large absorption capability, the achieved absorbed light power-to-temperature sensitivity is maintained at the level of a standard black spray. Finally, we show that while black spray has emissivity similar to a black body, the plasmonic absorber features a very low infra-red emissivity of almost 0.16, demonstrating its capability as selective coating for applications with operating temperatures up to 400°C, above which the nano-structure starts to deform. PMID:25418040

  3. Rapid-response low infrared emission broadband ultrathin plasmonic light absorber.

    PubMed

    Tagliabue, Giulia; Eghlidi, Hadi; Poulikakos, Dimos

    2014-01-01

    Plasmonic nanostructures can significantly advance broadband visible-light absorption, with absorber thicknesses in the sub-wavelength regime, much thinner than conventional broadband coatings. Such absorbers have inherently very small heat capacity, hence a very rapid response time, and high light power-to-temperature sensitivity. Additionally, their surface emissivity can be spectrally tuned to suppress infrared thermal radiation. These capabilities make plasmonic absorbers promising candidates for fast light-to-heat applications, such as radiation sensors. Here we investigate the light-to-heat conversion properties of a metal-insulator-metal broadband plasmonic absorber, fabricated as a free-standing membrane. Using a fast IR camera, we show that the transient response of the absorber has a characteristic time below 13 ms, nearly one order of magnitude lower than a similar membrane coated with a commercial black spray. Concurrently, despite the small thickness, due to the large absorption capability, the achieved absorbed light power-to-temperature sensitivity is maintained at the level of a standard black spray. Finally, we show that while black spray has emissivity similar to a black body, the plasmonic absorber features a very low infra-red emissivity of almost 0.16, demonstrating its capability as selective coating for applications with operating temperatures up to 400°C, above which the nano-structure starts to deform. PMID:25418040

  4. Rapid-Response Low Infrared Emission Broadband Ultrathin Plasmonic Light Absorber

    NASA Astrophysics Data System (ADS)

    Tagliabue, Giulia; Eghlidi, Hadi; Poulikakos, Dimos

    2014-11-01

    Plasmonic nanostructures can significantly advance broadband visible-light absorption, with absorber thicknesses in the sub-wavelength regime, much thinner than conventional broadband coatings. Such absorbers have inherently very small heat capacity, hence a very rapid response time, and high light power-to-temperature sensitivity. Additionally, their surface emissivity can be spectrally tuned to suppress infrared thermal radiation. These capabilities make plasmonic absorbers promising candidates for fast light-to-heat applications, such as radiation sensors. Here we investigate the light-to-heat conversion properties of a metal-insulator-metal broadband plasmonic absorber, fabricated as a free-standing membrane. Using a fast IR camera, we show that the transient response of the absorber has a characteristic time below 13 ms, nearly one order of magnitude lower than a similar membrane coated with a commercial black spray. Concurrently, despite the small thickness, due to the large absorption capability, the achieved absorbed light power-to-temperature sensitivity is maintained at the level of a standard black spray. Finally, we show that while black spray has emissivity similar to a black body, the plasmonic absorber features a very low infra-red emissivity of almost 0.16, demonstrating its capability as selective coating for applications with operating temperatures up to 400°C, above which the nano-structure starts to deform.

  5. Validation of Improved Broadband Shortwave and Longwave Fluxes Derived From GOES

    NASA Technical Reports Server (NTRS)

    Khaiyer, Mandana M.; Nordeen, Michele L.; Palikonda, Rabindra; Yi, Yuhong; Minnis, Patrick; Doelling, David R.

    2009-01-01

    Broadband (BB) shortwave (SW) and longwave (LW) fluxes at TOA (Top of Atmosphere) are crucial parameters in the study of climate and can be monitored over large portions of the Earth's surface using satellites. The VISST (Visible Infrared Solar Split-Window Technique) satellite retrieval algorithm facilitates derivation of these parameters from the Geostationery Operational Environmental Satellites (GOES). However, only narrowband (NB) fluxes are available from GOES, so this derivation requires use of narrowband-to-broadband (NB-BB) conversion coefficients. The accuracy of these coefficients affects the validity of the derived broadband (BB) fluxes. Most recently, NB-BB fits were re-derived using the NB fluxes from VISST/GOES data with BB fluxes observed by the CERES (Clouds and the Earth's Radiant Energy Budget) instrument aboard Terra, a sun-synchronous polar-orbiting satellite that crosses the equator at 10:30 LT. Subsequent comparison with ARM's (Atmospheric Radiation Measurement) BBHRP (Broadband Heating Rate Profile) BB fluxes revealed that while the derived broadband fluxes agreed well with CERES near the Terra overpass times, the accuracy of both LW and SW fluxes decreased farther away from the overpass times. Terra's orbit hampers the ability of the NB-BB fits to capture diurnal variability. To account for this in the LW, seasonal NB-BB fits are derived separately for day and night. Information from hourly SW BB fluxes from the Meteosat-8 Geostationary Earth Radiation Budget (GERB) is employed to include samples over the complete solar zenith angle (SZA) range sampled by Terra. The BB fluxes derived from these improved NB-BB fits are compared to BB fluxes computed with a radiative transfer model.

  6. Optical BEAMTAP beam-forming and jammer-nulling system for broadband phased-array antennas.

    PubMed

    Kriehn, G; Kiruluta, A; Silveira, P E; Weaver, S; Kraut, S; Wagner, K; Weverka, R T; Griffiths, L

    2000-01-10

    We present an approach to receive-mode broadband beam forming and jammer nulling for large adaptive antenna arrays as well as its efficient and compact optical implementation. This broadband efficient adaptive method for true-time-delay array processing (BEAMTAP) algorithm decreases the number of tapped delay lines required for processing an N-element phased-array antenna from N to only 2, producing an enormous savings in delay-line hardware (especially for large broadband arrays) while still providing the full NM degrees of freedom of a conventional N-element time-delay-and-sum beam former that requires N tapped delay lines with M taps each. This allows the system to adapt fully and optimally to an arbitrarily complex spatiotemporal signal environment that can contain broadband signals of interest, as well as interference sources and narrow-band and broadband jammers--all of which can arrive from arbitrary angles onto an arbitrarily shaped array--thus enabling a variety of applications in radar, sonar, and communication. This algorithm is an excellent match with the capabilities of radio frequency (rf) photonic systems, as it uses a coherent optically modulated fiber-optic feed network, gratings in a photorefractive crystal as adaptive weights, a traveling-wave detector for generating time delay, and an acousto-optic device to control weight adaptation. Because the number of available adaptive coefficients in a photorefractive crystal is as large as 10(9), these photonic systems can adaptively control arbitrarily large one- or two-dimensional antenna arrays that are well beyond the capabilities of conventional rf and real-time digital signal processing techniques or alternative photonic techniques. PMID:18337889

  7. Ultra-broadband sound absorption by acoustic metamaterials

    NASA Astrophysics Data System (ADS)

    Jiang, Xue; Liang, Bin; Cheng, Jian-Chun

    2015-03-01

    Metamaterials with extraordinary properties unavailable in nature have opened up new design possibilities. Acoustic absorbers are of particular significances for acoustics-based devices and find applications in various scenarios, but subject to the inherent restriction of the natural acoustical parameters and limited operating bandwidth. We report the theoretical design, numerical calculation and experimental study on the realization of a metamaterial-based acoustic absorber with a simple yet efficient structure. The proposed acoustic absorber works in an ultra-broad band without restricted by the material type or requiring extra absorbing material. Such distinct effects stem from the localization and dissipation of different spectrum components at predesigned spatial positions. Theoretical predictions developed based on classical acoustic theory agree well with numerical and experimental results. The realization of ultra-broadband acoustic absorber with unique properties of stiffness and environmental-friendliness has paved the way for designing conceptual acoustic devices, and has potential applications in situations with special requirements on acoustic absorption characteristics. Key Laboratory of Modern Acoustics, MOE, Department of Physics, Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, China.

  8. Broadband metasurface holograms: toward complete phase and amplitude engineering.

    PubMed

    Wang, Qiu; Zhang, Xueqian; Xu, Yuehong; Gu, Jianqiang; Li, Yanfeng; Tian, Zhen; Singh, Ranjan; Zhang, Shuang; Han, Jiaguang; Zhang, Weili

    2016-01-01

    As a revolutionary three-dimensional imaging technique, holography has attracted wide attention for its ability to photographically record a light field. However, traditional phase-only or amplitude-only modulation holograms have limited image quality and resolution to reappear both amplitude and phase information required of the objects. Recent advances in metasurfaces have shown tremendous opportunities for using a planar design of artificial meta-atoms to shape the wave front of light by optimal control of both its phase and amplitude. Inspired by the concept of designer metasurfaces, we demonstrate a novel amplitude-phase modulation hologram with simultaneous five-level amplitude modulation and eight-level phase modulation. Such a design approach seeks to turn the perceived disadvantages of the traditional phase or amplitude holograms, and thus enable enhanced performance in resolution, homogeneity of amplitude distribution, precision, and signal-to-noise ratio. In particular, the unique holographic approach exhibits broadband characteristics. The method introduced here delivers more degrees of freedom, and allows for encoding highly complex information into designer metasurfaces, thus having the potential to drive next-generation technological breakthroughs in holography. PMID:27615519

  9. Nonperiodic metallic gratings transparent for broadband terahertz waves

    NASA Astrophysics Data System (ADS)

    Fan, Ren-Hao; Ren, Xiao-Ping; Peng, Ru-Wen; Huang, Xian-Rong; Wang, Mu

    Recently, we demonstrate both theoretically and experimentally that nonperiodic metallic gratings can become transparent for broadband terahertz waves. Quasiperiodic and disordered metallic gratings effectively weaken and even eliminate Wood's anomalies, which are the diffraction-related characters of periodic gratings. Consequently, both the transparence bandwidth and transmission efficiency are significantly increased due to the structural aperiodicity. Furthermore, we show that for a specific light source, for example, a line source, a corresponding nonperiodic transparent grating can be also designed. We expect that our findings can be applied for transparent conducting panels, perfect white-beam polarizers, antireflective conducting solar cells, and beyond. References: X. P. Ren, R. H. Fan, R. W. Peng, X. R. Huang, D. H. Xu, Y. Zhou, and Mu Wang, Physical Review B, 91, 045111 (2015); R. H. Fan, R. W. Peng, X. R. Huang, J. Li, Y. Liu, Q. Hu, Mu. Wang, and X. Zhang, Advanced Materials, 24, 1980 (2012); and X. R. Huang, R. W. Peng, and R. H. Fan. Physical Review Letters, 105, 243901 (2010).

  10. Progress in Measurement of Carbon Dioxide Using a Broadband LIDAR

    NASA Technical Reports Server (NTRS)

    Heaps, William S.; Georgieva, Elena; Huang, Wen

    2010-01-01

    Innovative active system using advanced source technology development will enable precise daytime or nighttime measurements of column CO2. Directly responds to NRC DS ASCENDS mission. Number of lasers is reduced compared to competing technologies which reduces the complexity of sensor and thus the cost and risk of failure. Knowledge gained from previously developed passive sensor decreases the risk and cost of the present lidar system development. The instrument can play a significant role as an intercomparison instrument for OCO (Orbiting Carbon Observatory) if it is rebuilt and launched as well as other laser based instruments under development for participation in ASCENDS. It can play a role as an airborne instrument in its own right in addressing the problems of scale arising from differences between point observations by the existing ground based CO2 network and wider area measurements obtained by satellites. Developed 2.0 micron broadband system as well and will compare performance of both systems to choose optimal approach for ASCENDS. Have begun development of approach that uses array detectors instead of APD. This approach will have lower noise than APD and may simplify design of the detector optical train.

  11. Future integrated broadband fiber, wireless, and satellite networks

    NASA Astrophysics Data System (ADS)

    Chan, Vincent W. S.

    2006-10-01

    With the increasing technical maturity in fiber, wireless and satellite communication technologies, new horizons are becoming feasible for future broadband networks, providing economical data rates well in excess of Gbps for stationary and mobile users as well as novel applications these advanced network services will permit. This talk explores the future architecture possibilities of such a network using new and radical technology building blocks such as: free space laser communications, multiple access multi-beam data satellite communications, novel all-optical network transport/switching and analog transmission and processing over optical carriers that support coherent distributed platform sensing and communications. We will articulate why we have to design this new network across layers from the Physical Layer to the Network and Transport Layers (even the Application Layer). Not only can future network performance and cost undergo quantum-leap improvements; such a network can have profound transforming effects on space and terrestrial system architectures for sensing, healthcare, early warning systems, disaster relief, research collaborations and other new commercial applications.

  12. A cost model for broadband access networks: FTTx versus WiMAX

    NASA Astrophysics Data System (ADS)

    Pereira, João Paulo Ribeiro

    2007-09-01

    Local communities and governments are taking various steps to fight the so-called "digital divide" between well served urban communities and undeserved areas. In order to make broadband access available to these under served areas, several technical solutions are available with the capacity to provide high speed Internet access, video, telephony services, etc. This paper presents a cost-model and a tool for the evaluation of broadband access technologies (xDSL, HFC, FTTx, WiMAX, PLC and satellite), and compares two technologies: FTTx and WiMAX. Our tool compares these different access technologies in different scenarios, and examining the capital expense and deployment of building access networks with the same requisite performance using each technology. The cost model is limited to the access part of the network. The results obtained by our evaluation tool give the possibility to compare several BB access technologies, and support the decision about which is the better technological solution for a given scenario

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

    NASA Technical Reports Server (NTRS)

    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.

  14. Laboratory measurements of high-frequency, acoustic broadband backscattering from sea ice and crude oil.

    PubMed

    Bassett, Christopher; Lavery, Andone C; Maksym, Ted; Wilkinson, Jeremy P

    2015-01-01

    Recent decreases in summer sea ice cover are spurring interest in hydrocarbon extraction and shipping in Arctic waters, increasing the risk of an oil spill in ice covered waters. With advances in unmanned vehicle operation, there is an interest in identifying techniques for remote, underwater detection of oil spills from below. High-frequency (200-565 kHz), broadband acoustic scattering data demonstrate that oil can be detected and quantified under laboratory grown sea ice and may be of use in natural settings. A simple scattering model based on the reflection coefficients from the interfaces agrees well with the data. PMID:25618096

  15. Tip geometry effects on the model helicopter rotor low frequency broadband noise

    NASA Technical Reports Server (NTRS)

    Humbad, N. G.; Harris, W. L.

    1981-01-01

    The effect of rotor blade tip shapes and performance parameters on the low frequency broadband noise (LFBN) is investigated experimentally. The experimental results show 2 to 5 dB reductions for swept geometries compared with square tip blades at constant blade loading. A theoretical model is formulated which includes a detailed lift response function. For the square tip blades, theoretical results are found to be in good agreement with the experimental results. While the effects of advance ratio and tip speed on the LFBN are explicable, those of blade loading are not clearly understood.

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

    NASA Astrophysics Data System (ADS)

    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.

  17. Future large broadband switched satellite communications networks

    NASA Technical Reports Server (NTRS)

    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.

  18. A broadband multimedia TeleLearning system

    SciTech Connect

    Wang, Ruiping; Karmouch, A.

    1996-12-31

    In this paper we discuss a broadband multimedia TeleLearning system under development in the Multimedia Information Research Laboratory at the University of Ottawa. The system aims at providing a seamless environment for TeleLearning using the latest telecommunication and multimedia information processing technology. It basically consists of a media production center, a courseware author site, a courseware database, a courseware user site, and an on-line facilitator site. All these components are distributed over an ATM network and work together to offer a multimedia interactive courseware service. An MHEG-based model is exploited in designing the system architecture to achieve the real-time, interactive, and reusable information interchange through heterogeneous platforms. The system architecture, courseware processing strategies, courseware document models are presented.

  19. Broadband optical modulators based on graphene supercapacitors.

    PubMed

    Polat, Emre O; Kocabas, Coskun

    2013-01-01

    Optical modulators are commonly used in communication and information technology to control intensity, phase, or polarization of light. Electro-optic, electroabsorption, and acousto-optic modulators based on semiconductors and compound semiconductors have been used to control the intensity of light. Because of gate tunable optical properties, graphene introduces new potentials for optical modulators. The operation wavelength of graphene-based modulators, however, is limited to infrared wavelengths due to inefficient gating schemes. Here, we report a broadband optical modulator based on graphene supercapacitors formed by graphene electrodes and electrolyte medium. The transparent supercapacitor structure allows us to modulate optical transmission over a broad range of wavelengths from 450 nm to 2 μm under ambient conditions. We also provide various device geometries including multilayer graphene electrodes and reflection type device geometries that provide modulation of 35%. The graphene supercapacitor structure together with the high-modulation efficiency can enable various active devices ranging from plasmonics to optoelectronics. PMID:24215484

  20. Superconducting Quantum Arrays for Broadband RF Systems

    NASA Astrophysics Data System (ADS)

    Kornev, V.; Sharafiev, A.; Soloviev, I.; Kolotinskiy, N.; Mukhanov, O.

    2014-05-01

    Superconducting Quantum Arrays (SQAs), homogenous arrays of Superconducting Quantum Cells, are developed for implementation of broadband radio frequency (RF) systems capable of providing highly linear magnetic signal to voltage transfer with high dynamic range, including active electrically small antennas (ESAs). Among the proposed quantum cells which are bi-SQUID and Differential Quantum Cell (DQC), the latter delivered better performance for SQAs. A prototype of the transformer-less active ESA based on a 2D SQA with nonsuperconducting electric connection of the DQCs was fabricated using HYPRES niobium process with critical current density 4.5 kA/cm2. The measured voltage response is characterized by a peak-to-peak swing of ~100 mV and steepness of ~6500 μV/μT.

  1. Broadband polygonal invisibility cloak for visible light.

    PubMed

    Chen, Hongsheng; Zheng, Bin

    2012-01-01

    Invisibility cloaks have recently become a topic of considerable interest thanks to the theoretical works of transformation optics and conformal mapping. The design of the cloak involves extreme values of material properties and spatially dependent parameter tensors, which are very difficult to implement. The realization of an isolated invisibility cloak in the visible light, which is an important step towards achieving a fully movable invisibility cloak, has remained elusive. Here, we report the design and experimental demonstration of an isolated polygonal cloak for visible light. The cloak is made of several elements, whose electromagnetic parameters are designed by a linear homogeneous transformation method. Theoretical analysis shows the proposed cloak can be rendered invisible to the rays incident from all the directions. Using natural anisotropic materials, a simplified hexagonal cloak which works for six incident directions is fabricated for experimental demonstration. The performance is validated in a broadband visible spectrum. PMID:22355767

  2. Broadband polygonal invisibility cloak for visible light

    PubMed Central

    Chen, Hongsheng; Zheng, Bin

    2012-01-01

    Invisibility cloaks have recently become a topic of considerable interest thanks to the theoretical works of transformation optics and conformal mapping. The design of the cloak involves extreme values of material properties and spatially dependent parameter tensors, which are very difficult to implement. The realization of an isolated invisibility cloak in the visible light, which is an important step towards achieving a fully movable invisibility cloak, has remained elusive. Here, we report the design and experimental demonstration of an isolated polygonal cloak for visible light. The cloak is made of several elements, whose electromagnetic parameters are designed by a linear homogeneous transformation method. Theoretical analysis shows the proposed cloak can be rendered invisible to the rays incident from all the directions. Using natural anisotropic materials, a simplified hexagonal cloak which works for six incident directions is fabricated for experimental demonstration. The performance is validated in a broadband visible spectrum. PMID:22355767

  3. Energetic electron interaction with broadband ULF waves

    NASA Astrophysics Data System (ADS)

    Vassiliadis, D.; Tornquist, M.; Koepke, M. E.; Shao, X.

    2014-12-01

    Electron energization in Earth's radiation belts is frequently explained in terms of an internal process whose effects can be enhanced by radial diffusion. Both types of energization include resonant interactions of the electrons with low-frequency waves. Spectra of such waves are often assumed to be broadband and to have a typical range of negative spectral indices (similar to 1/f), however recent studies show that power spectra of ground geomagnetic pulsations are significantly more complex. We use particle tracing simulations in a realistic magnetospheric field configuration to determine the effects of the spectral parameters. The low-frequency wave contribution to the radial diffusion coefficient is found to vary as a function of the spectral index magnitude. Research was supported by NSF/AGS 0741841.

  4. Frequency Doubling Broadband Light in Multiple Crystals

    SciTech Connect

    ALFORD,WILLIAM J.; SMITH,ARLEE V.

    2000-07-26

    The authors compare frequency doubling of broadband light in a single nonlinear crystal with doubling in five crystals with intercrystal temporal walk off compensation, and with doubling in five crystals adjusted for offset phase matching frequencies. Using a plane-wave, dispersive numerical model of frequency doubling they study the bandwidth of the second harmonic and the conversion efficiency as functions of crystal length and fundamental irradiance. For low irradiance the offset phase matching arrangement has lower efficiency than a single crystal of the same total length but gives a broader second harmonic bandwidth. The walk off compensated arrangement gives both higher conversion efficiency and broader bandwidth than a single crystal. At high irradiance, both multicrystal arrangements improve on the single crystal efficiency while maintaining broad bandwidth.

  5. Feedback controllers for broadband active noise reduction

    NASA Astrophysics Data System (ADS)

    Petitjean, Benoit; Legrain, Isabelle

    1994-09-01

    The aim of the present paper is to demonstrate the efficiency of an LQG-based controller for the active control of the acoustic field radiated by a rectangular panel. This topic has been of interest for numerous researchers in the past 10 or 15 years, but very little attention has been paid to broadband disturbances occurring in a relatively high frequency range. These are unfortunately common features of noise perturbations in realistic structures such as airplanes or helicopters. The few articles that deal with this problem provide very scarce experimental results and are related to frequency bands where the structure dynamics is rather poor. From the outset, the problem at hand involves numerous difficulties, such as the modeling of the active structure itself and the possible large size of the controller. In the following, the experimental setup is described, then the controller design procedure is developed and finally some experimental results are shown that prove the efficiency of the method.

  6. Broadband spectrophotometry on nonplanar EUV multilayer optics

    NASA Astrophysics Data System (ADS)

    Balasa, I.; Blaschke, H.; Ristau, D.

    2011-04-01

    A reliable and compact EUV-spectrometer adapted for the broadband analysis of curved EUV-optics for near normal incidence applications will be presented. Using a specific design for the specimen holder, the limits of both types of samples, convex and concave, can be verified. The capability of the device is confirmed by investigations in the spectral reflectivity of a single EUV-multilayer mirror deposited on a silicon wafer. Its radius of curvature (ROC) is continuously adjustable, providing a direct comparison of the detected peak reflectivity, peak location and spectral bandwidth in dependence on its curvature. The range of curvature applied is in compliance with optics specifications of current projection systems for EUV-lithography.

  7. Broad-band multisection electrooptic modulators

    NASA Astrophysics Data System (ADS)

    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.

  8. Tunable Broadband Printed Carbon Transparent Conductor

    NASA Astrophysics Data System (ADS)

    Xu, Yue; Wan, Jiayu

    Transparent conductors have been widely applied in solar cells, transparent smart skins, and sensing/imaging antennas, etc. Carbon-based transparent conductor has attracted great attention for its low cost and broad range transparency. Ion intercalation has been known to highly dope graphitic materials, thereby tuning materials' optoelectronic properties. For the first time, we successfully tune the optical transmittance of a reduced graphene oxide (RGO)/CNT network from mid-IR range to visible range by means of Li-ion intercalation/deintercalation. We also observed a simultaneous increase of the electrical conductivity with the Li-ion intercalation. This printed carbon hybrid thin film was prepared through all solution processes and was easily scalable. This study demonstrates the possibility of using ion intercalation for low cost, tunable broadband transparent conductors.

  9. Statistical dispersion relation for spatially broadband fields.

    PubMed

    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

  10. A broadband scalar optical vortex coronagraph

    NASA Astrophysics Data System (ADS)

    Errmann, Ronnie; Minardi, Stefano; Pertsch, Thomas

    2014-07-01

    In recent years, new coronagraphic schemes have been proposed, the most promising being the optical vortex phase mask coronagraphs. In our work, a new scheme of broadband optical scalar vortex coronagraph is proposed and characterized experimentally in the laboratory. Our setup employs a pair of computer generated phase gratings (one of them containing a singularity) to control the chromatic dispersion of phase plates and achieves a constant peak-to-peak attenuation below 1:1000 over a bandwidth of 120 nm centered at 700 nm. An inner working angle of λ/D is demonstrated along with a raw contrast of 11.5magnitudes at 2λ/D. A more compact setup achieves a peak-to-peak attenuation below 1:1000 over a bandwidth of 60 nm with the other results remaining the same.

  11. Broadband optical isolator based on helical metamaterials.

    PubMed

    Cao, Hu; Yang, ZhenYu; Zhao, Ming; Wu, Lin; Zhang, Peng

    2015-05-01

    Based on helical metamaterials, a new broadband optical isolator with a triple-helix structure is proposed in this paper. The right-handed circularly polarized light can transmit through the isolator with its polarization unchanged. The reverse propagating light, which is caused by the reflection of the latter optical devices, is converted into left-handed circularly polarized light that is suppressed by the proposed isolator because of absorption. Our design has some unprecedented advantages such as broad frequency ranges and a compact structure; moreover, neither polarizers nor adscititious magnetic fields are required. Properties of the isolator are investigated using the finite-difference time-domain method, and this phenomenon is studied by the mechanism of helical antenna theory. PMID:26366900

  12. On helicopter rotor low frequency broadband noise

    NASA Technical Reports Server (NTRS)

    Williams, Morgan; Harris, Wesley L.

    1985-01-01

    The effect of shear-layer-type inflow turbulence on the low-frequency broadband noise of a model helicopter rotor is experimentally studied. The measurements and the one-dimensional energy spectral density indicate that the upstream airfoil wake turbulence is nonisotropic, but approaches isotropy at high wavenumbers. Turbulence measurements also indicate that the wake turbulence is weak. The effect of the inflow turbulence intensity on the peak sound pressure level follows an intensity-velocity squared scaling law. A number of length scales and turbulence intensities exist which can be measured in the airfoil wake depending on the position at which the measurements are taken. Comparison of experimental and theoretical sound pressure power spectral densities indicates that the initial anisotropy of the inflow turbulence does not invalidate the isotropic turbulence assumption made in noise prediction models as long as measured turbulence intensities and length scales are used.

  13. Ultra-broadband terahertz metamaterial absorber

    NASA Astrophysics Data System (ADS)

    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.

  14. Broadband Seismic Study of the Dominican Republic

    NASA Astrophysics Data System (ADS)

    Pulliam, J.; Polanco Rivera, E.; Pujols Guridy, R.; Huerfano Moreno, V. A.; Lopez, A. M.

    2014-12-01

    The Northeast Caribbean Plate Boundary Zone (NCPBZ) is characterized by oblique subduction of oceanic crust belonging to the North American Plate, a broad zone of deformation to accommodate strain, and the development of transform and normal faults on and around the island of Hispaniola. Other features may include the formation of a new microplates, rearrangement and aggregation of crustal fragments into new islands, and rotations of the microplates. Numerous issues regarding the nature and timing of formation of the features described above, their roles in regional tectonics and even whether they exist at all, remain unresolved. Our short-term goal is to better constraint lithospheric structure and identify active earthquake faults with a temporary broadband seismic network in the Dominican Republic. The oblique-subduction-to-strike-slip transition found in the NCPBZ is representative of numerous locales around the world, so lessons learned here may inform our understanding of plate tectonics broadly. In 2013-2014 we installed sixteen broadband seismic stations in the Dominican Republic. The temporary network will remain in place for two years. Data acquired by the temporary network will be integrated with data recorded by existing seismic facilities in the region and the combined dataset will be used for a series of analyses that will, collectively, allow us to image lithospheric structure and aid seismic hazard assessment for the island of Hispaniola. Preliminary results will be presented from the deployment, including regional earthquake locations and improved 1D Earth structure as well as plans for collaborations between regional seismic networks and local capacity-building.

  15. The broadband spectrum of Centaurus X-3

    NASA Astrophysics Data System (ADS)

    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.

  16. Broadband fitting approach for the application of supercontinuum broadband laser absorption spectroscopy to combustion environments

    NASA Astrophysics Data System (ADS)

    Göran Blume, Niels; Ebert, Volker; Dreizler, Andreas; Wagner, Steven

    2016-01-01

    In this work, a novel broadband fitting approach for quantitative in-flame measurements using supercontinuum broadband laser absorption spectroscopy (SCLAS) is presented. The application and verification of this approach in an atmospheric, laminar, non-premixed CH4/air flame (Wolfhard-Parker burner, WHP) is discussed. The developed fitting scheme allows for an automatic recognition and fitting of a B-spline curve reference intensity for SCLAS broadband measurements while automatically removing the influence of absorption peaks. This approach improves the fitting residual locally (in between absorption lines) and globally by 23% and 13% respectively, while improving the in-flame SNR by a factor of 2. Additionally, the approach inherently improves the time-wavelength-correlation based on recorded in-flame measurements itself in combination with a theoretical spectrum of the analyte. These improvements have allowed for the recording of complete spatially resolved methane concentration profiles in the WHP burner. Comparison of the measured absolute mole fraction profile for methane with previously measured reference data shows excellent agreement in position, shape and absolute values. These improvements are a prerequisite for the application of SCLAS in high-pressure combustion systems.

  17. Comparative Noise Performance of Portable Broadband Sensor Emplacements

    NASA Astrophysics Data System (ADS)

    Sweet, Justin; Arias-Dotson, Eliana; Beaudoin, Bruce; Anderson, Kent

    2015-04-01

    IRIS PASSCAL has supported portable broadband seismic experiments for close to 30 years. During that time we have seen a variety of sensor vaults deployed. The vaults deployed fall into two broad categories, a PASSCAL style vault and a Flexible Array style vault. The PASSCAL vault is constructed of materials available in-county and it is the Principle Investigator (PI) who establishes the actual field deployed design. These vaults generally are a large barrel placed in a ~1 m deep hole. A small pier, decoupled from the barrel, is fashioned in the bottom of the vault (either cement, paving stone or tile) for the sensor placement. The sensor is insulated and protected. Finally the vault is sealed and buried under ~30 cm of soil. The Flexible Array vault is provided to PIs by the EarthScope program, offering a uniform portable vault for these deployments. The vault consists of a 30 cm diameter by 0.75 cm tall piece of plastic sewage pipe buried with ~10 cm of pipe above grade. A rubber membrane covers the bottom and cement was poured into the bottom, coupling the pier to the pipe. The vault is sealed and buried under ~30 cm of soil. Cost, logistics, and the availability of materials in-country are usually the deciding factors for PIs when choosing a vault design and frequently trades are made given available resources. Recently a third type of portable broadband installation, direct burial, is being tested. In this case a sensor designed for shallow, direct burial is installed in a ~20 cm diameter by ~1 m deep posthole. Direct burial installation costs are limited to the time and effort required to dig the posthole and emplace the sensor. Our initial analyses suggest that direct burial sensors perform as well and at times better than sensor in vaults on both horizontal and vertical channels across a range of periods (<1 s to 100 s). Moving towards an instrument pool composed entirely of direct burial sensors (some with integrated digitizers) could yield higher

  18. Solution processable broadband transparent mixed metal oxide nanofilm optical coatings via substrate diffusion doping

    NASA Astrophysics Data System (ADS)

    Glynn, Colm; Aureau, Damien; Collins, Gillian; O'Hanlon, Sally; Etcheberry, Arnaud; O'Dwyer, Colm

    2015-11-01

    . Here, we report a facile solution processed technique for the formation of a transparent thin film through an inter-diffusion process involving substrate dopant species at a range of low annealing temperatures compatible with processing conditions required by many state-of-the-art devices. The inter-diffusion process facilitates the movement of Si, Na and O species from the substrate into the as-deposited vanadium oxide thin film forming a composite fully transparent V0.0352O0.547Si0.4078Na0.01. Thin film X-ray diffraction and Raman scattering spectroscopy show the crystalline component of the structure to be α-NaVO3 within a glassy matrix. This optical coating exhibits high broadband transparency, exceeding 90-97% absolute transmission across the UV-to-NIR spectral range, while having low roughness and free of surface defects and pinholes. The production of transparent films for advanced optoelectronic devices, optical coatings, and low- or high-k oxides is important for planar or complex shaped optics or surfaces. It provides opportunities for doping metal oxides to ternary, quaternary or other mixed metal oxides on glass, encapsulants or other substrates that facilitate diffusional movement of dopant species. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06184a

  19. Broadband infrared beam splitter for spaceborne interferometric infrared sounder.

    PubMed

    Yu, Tianyan; Liu, Dingquan; Qin, Yang

    2014-10-01

    A broadband infrared beam splitter (BS) on ZnSe substrate used for the spaceborne interferometric infrared sounder (SIIRS) is studied in the spectral range of 4.44-15 μm. Both broadband antireflection coating and broadband beam-splitter coating in this BS are designed and tested. To optimize the optical properties and the stability of the BS, suitable infrared materials were selected, and improved deposition techniques were applied. The designed structures matched experimental data well, and the properties of the BS met the application specification of SIIRS. PMID:25322240

  20. Separation of piano tones into tonal and broadband components

    NASA Astrophysics Data System (ADS)

    Keane, Martin

    2005-09-01

    Few studies have proposed simple objective methods to evaluate the quality of piano tones. Recordings of both sound and vibration of six pianos (two grands and four uprights) were analyzed. The results suggest an objective measure for piano tone quality. A method is given for splitting recorded tones into tonal and broadband components. The broadband vibration was found to be more intense in the upright pianos than in the grand pianos, this is due to differences in the construction of the keybed. There was no such difference found in the tonal component. These results suggest the hypothesis that a smaller broadband component correlates with higher quality in piano tones.

  1. Ultra-broadband perfect cross polarization conversion metasurface

    NASA Astrophysics Data System (ADS)

    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.

  2. Design of a new broadband monopole optical nano-antenna

    NASA Astrophysics Data System (ADS)

    Zhou, Rongguo; Ding, Jun; Arigong, Bayaner; Lin, Yuankun; Zhang, Hualiang

    2013-11-01

    In this paper, we propose a novel design of broadband monopole optical nano-antennas. It is consisted of a corrugated half elliptical patch inside an elliptical aperture. By adjusting the dimensions of the elliptical patch and the elliptical aperture, the overall performance of the proposed monopole nano-antenna can be made remarkable broadband. Full wave electromagnetic simulations have been used to investigate the effects of different parameters on the nano-antenna performance. Moreover, the proposed broadband nano-antenna can support light waves with different polarizations. It is expected that the new optical antenna will pave the way towards the development of high performance optical antennas and optical systems.

  3. Statistically Based Approach to Broadband Liner Design and Assessment

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    The Southern California Earthquake Center (SCEC) Broadband Platform is a collaborative software development project involving SCEC researchers, graduate students, and the SCEC Community Modeling Environment. The SCEC Broadband Platform 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 Broadband Platform runs earthquake rupture and wave propagation modeling software to calculate seismograms of a historical earthquake for which observed strong ground motion data is available. Also in validation mode, the Broadband Platform 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. During the past year, we have modified the software to enable the addition of a large number of historical events, and we are now adding validation simulation inputs and observational data for 23 historical events covering the Eastern and Western United States, Japan, Taiwan, Turkey, and Italy. 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. By establishing an interface between scientific modules with a common set of input and output files, the Broadband

  5. Broadband Emission Spectra from the Cygnus X-3 Jet in the Soft Spectral State

    NASA Astrophysics Data System (ADS)

    Zhang, Jian-Fu; Lu, Ju-Fu

    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.

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

    SciTech Connect

    Zhang, Jian-Fu; Lu, Ju-Fu E-mail: lujf@xmu.edu.cn

    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.

  7. Microelectromechanical Systems (MEMS) Broadband Light Source Developed

    NASA Technical Reports Server (NTRS)

    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

  8. Considerations of broadband seismic observation on Mars

    NASA Astrophysics Data System (ADS)

    Nishikawa, Y.; Kurita, K.; Araya, A.; Hori, T.; Kobayashi, N.; Shiraishi, H.; Kakuma, H.; Ishihara, Y.

    2010-12-01

    The surface of Mars has been extensively investigated and huge amount of data have been acquired such as high Res images. On the other hand interior of the Mars has been only weakly constrained by the mean density, the moment of inertia and gravity data. The size of core is poorly constrained and negatively correlated with the core density. High dissipation state is reported for the mantle by tidal interaction (Bills et al 2006), which is against a conventional view of small,cool planet. To clarify these points seismic observation on Mars is deadly needed. Japan Mars exploration project(MELOS) is now under discussion and it includes seismic measurements for determination the interior structure of Mars such as the core size, its state and attenuation in the mantle. Our plan is to install broadband high sensitivity seismometers,which are intended to detect continuous excitation of free oscillation by atmospheric turbulence. In this presentation we would like to show a basic design of broadband high sensitivity seismometer as well as environment protection designs. The basic parts are composed of a long period pendulum, laser interferometry and its control feedback electricity. As for the environment protection design,the following factors are important. 1. Surface condition. Martian surface is composed of stones gravels and sand. Drift is expected to occur due to the sudden change in ground slope. We need a device for self adjustment to keep the horizontal. 2. Temperature. Surface temperature at Martian equator is expected to vary between 190 to 300K. We have to consider changes in spring tension, thermal expansion of components and changes in circuit constants. 3. Surface wind. Inhomogeneously heated surface and topographic effect generate wind over 20m per second. We have to consider to lessen the effect of seismometer,even if we install the seismometer on the ground. 4. Radiation. Radiation that rains down on Mars is stronger because of thin atmosphere. Radiation

  9. Broadband light trapping based on periodically textured ZnO thin films

    NASA Astrophysics Data System (ADS)

    Liu, Bofei; Liang, Xuejiao; Liang, Junhui; Bai, Lisha; Gao, Haibo; Chen, Ze; Zhao, Ying; Zhang, Xiaodan

    2015-05-01

    -conductive, and large-scale periodically-textured ZnO TCFEs with broadband light trapping properties. A sheet resistance below 15 Ω sq-1 was achieved for the periodically-textured ZnO TCFEs, with a concomitant average transmission of 81% (including the glass substrate) in the 400-1100 nm spectral range, a haze improvement in a broadband spectral range, and a wider scattering angular domain. The proposed approach affords a promising alternative method to prepare periodically-textured TCFEs, which are essential for many optoelectronic device semiconductors, such as photovoltaic and display applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr01528f

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

    NASA Astrophysics Data System (ADS)

    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.

  11. 47 CFR 90.528 - Public safety broadband license.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... barring violations of law, rules or policy warranting denial of renewal. (e) The Public Safety Broadband... Security Bureaus. ... basis, a full financial accounting to the Commission, in a format to be set forth in the Network...

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

    SciTech Connect

    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.

  13. Low-frequency broadband noise generated by a model rotor

    NASA Technical Reports Server (NTRS)

    Aravamudan, K. S.; Harris, W. L.

    1979-01-01

    Low-frequency broadband noise generated by model rotors is attributed to the interaction of ingested turbulence with the rotor blades. The influence of free-stream turbulence in the low-frequency broadband noise radiation from model rotors has been experimentally investigated. The turbulence was generated in the M.I.T. anechoic wind tunnel facility with the aid of bipolar grids of various sizes. The spectra and the intensity of the low-frequency broadband noise have been studied as a function of parameters which characterize the turbulence and of helicopter performance parameters. The location of the peak intensity was observed to be strongly dependent on the rotor-tip velocity and on the longitudinal integral scale of turbulence. The size scale of turbulence had negligible effect on the intensity of low-frequency broadband noise. The experimental data show good agreement with an ad hoc model based on unsteady aerodynamics.

  14. Refractory plasmonics with titanium nitride: broadband metamaterial absorber.

    PubMed

    Li, Wei; Guler, Urcan; Kinsey, Nathaniel; Naik, Gururaj V; Boltasseva, Alexandra; Guan, Jianguo; Shalaev, Vladimir M; Kildishev, Alexander V

    2014-12-17

    A high-temperature stable broadband plasmonic absorber is designed, fabricated, and optically characterized. A broadband absorber with an average high absorption of 95% and a total thickness of 240 nm is fabricated, using a refractory plasmonic material, titanium nitride. This absorber integrates both the plasmonic resonances and the dielectric-like loss. It opens a path for the interesting applications such as solar thermophotovoltaics and optical circuits. PMID:25327161

  15. Excess wings in broadband dielectric spectroscopy

    NASA Astrophysics Data System (ADS)

    Candelaresi, S.; Hilfer, R.

    2014-12-01

    Analysis of excess wings in broadband dielectric spectroscopy data of glass forming materials provides evidence for anomalous time evolutions and fractional semigroups. Solutions of fractional evolution equations in frequency space are used to fit dielectric spectroscopy data of glass forming materials with a range between 4 and 10 decades in frequency. It is shown that with only three parameters (two relaxation times plus one exponent) excellent fits can be obtained for 5-methyl-2-hexanol and for methyl-m-toluate over up to 7 decades. The traditional Havriliak-Negami fit with three parameters (two exponents and one relaxation time) fits only 4-5 decades. Using a second exponent, as in Havriliak-Negami fits, the α-peak and the excess wing can be modeled perfectly with our theory for up to 10 decades for all materials at all temperatures considered here. Traditionally this can only be accomplished by combining two Havriliak-Negami functions with 7 parameters. The temperature dependent relaxation times are fitted with the Vogel-Tammann-Fulcher relation which provides the corresponding Vogel-Fulcher temperatures. The relaxation times turn out to obey almost perfectly the Vogel-Tammann-Fulcher law. Computable expressions of time dependent relaxation functions are also reported.

  16. Highly coherent modeless broadband semiconductor laser.

    PubMed

    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

  17. Electronic resonances in broadband stimulated Raman spectroscopy

    PubMed Central

    Batignani, G.; Pontecorvo, E.; Giovannetti, G.; Ferrante, C.; Fumero, G.; Scopigno, T.

    2016-01-01

    Spontaneous Raman spectroscopy is a formidable tool to probe molecular vibrations. Under electronic resonance conditions, the cross section can be selectively enhanced enabling structural sensitivity to specific chromophores and reaction centers. The addition of an ultrashort, broadband femtosecond pulse to the excitation field allows for coherent stimulation of diverse molecular vibrations. Within such a scheme, vibrational spectra are engraved onto a highly directional field, and can be heterodyne detected overwhelming fluorescence and other incoherent signals. At variance with spontaneous resonance Raman, however, interpreting the spectral information is not straightforward, due to the manifold of field interactions concurring to the third order nonlinear response. Taking as an example vibrational spectra of heme proteins excited in the Soret band, we introduce a general approach to extract the stimulated Raman excitation profiles from complex spectral lineshapes. Specifically, by a quantum treatment of the matter through density matrix description of the third order nonlinear polarization, we identify the contributions which generate the Raman bands, by taking into account for the cross section of each process. PMID:26728791

  18. HCIT Broadband Contrast Performance Sensitivity Studies

    NASA Technical Reports Server (NTRS)

    Sidick, Erkin; Shaklan, Stuart; Balasubramanian, Kunjithapatham

    2012-01-01

    The High Contrast Imaging Testbed (HCIT) at the Jet Propulsion Laboratory employs a broadband wavefront correction algorithm called Electric Field Conjugation (EFC) to obtain the required 10-10 contrast. This algorithm works with one deformable mirror (DM) to estimate the electric-field to be controlled, and with one or multiple DM's to create a "darkhole" in a predefined region of the image plane where terrestrial planets would be found. We have investigated the effects of absorbing dust particles on a flat optic, absorbing spots on the occulting mask, dead actuators on the DM, and the effects of control bandwidth on the efficiency of the EFC algorithm in a Lyot coronagraph configuration. The structural design of the optical system as well as the parameters of various optical elements used in the analysis is drawn from those of the HCIT system that have been implemented with one DM. The simulation takes into account the surface errors of various optical elements. Results of some of these studies have been verified by actual measurements.

  19. CAA broadband noise prediction for aeroacoustic design

    NASA Astrophysics Data System (ADS)

    Ewert, R.; Dierke, J.; Siebert, J.; Neifeld, A.; Appel, C.; Siefert, M.; Kornow, O.

    2011-08-01

    The current status of a computational aeroacoustics (CAA) approach to simulate broadband noise is reviewed. The method rests on the use of steady Reynolds averaged Navier-Stokes (RANS) simulation to describe the time-averaged motion of turbulent flow. By means of synthetic turbulence the steady one-point statistics (e.g. turbulence kinetic energy) and turbulent length- and time-scales of RANS are translated into fluctuations having statistics that very accurately reproduce the initial RANS target-setting. The synthetic fluctuations are used to prescribe sound sources which drive linear perturbation equations. The whole approach represents a methodology to solve statistical noise theory with state-of-the-art CAA tools in the time-domain. A brief overview of the synthetic turbulence model and its numerical discretization in terms of the random particle-mesh (RPM) and fast random particle-mesh (FRPM) method is given. Results are presented for trailing-edge noise, slat noise, and jet noise. Some problems related to the formulation of vortex sound sources are discussed.

  20. Silicon Micromachined Sensor for Broadband Vibration Analysis

    NASA Technical Reports Server (NTRS)

    Gutierrez, Adolfo; Edmans, Daniel; Cormeau, Chris; Seidler, Gernot; Deangelis, Dave; Maby, Edward

    1995-01-01

    The development of a family of silicon based integrated vibration sensors capable of sensing mechanical resonances over a broad range of frequencies with minimal signal processing requirements is presented. Two basic general embodiments of the concept were designed and fabricated. The first design was structured around an array of cantilever beams and fabricated using the ARPA sponsored multi-user MEMS processing system (MUMPS) process at the Microelectronics Center of North Carolina (MCNC). As part of the design process for this first sensor, a comprehensive finite elements analysis of the resonant modes and stress distribution was performed using PATRAN. The dependence of strain distribution and resonant frequency response as a function of Young's modulus in the Poly-Si structural material was studied. Analytical models were also studied. In-house experimental characterization using optical interferometry techniques were performed under controlled low pressure conditions. A second design, intended to operate in a non-resonant mode and capable of broadband frequency response, was proposed and developed around the concept of a cantilever beam integrated with a feedback control loop to produce a null mode vibration sensor. A proprietary process was used to integrat a metal-oxide semiconductor (MOS) sensing device, with actuators and a cantilever beam, as part of a compatible process. Both devices, once incorporated as part of multifunction data acquisition and telemetry systems will constitute a useful system for NASA launch vibration monitoring operations. Satellite and other space structures can benefit from the sensor for mechanical condition monitoring functions.

  1. Pricing by timing: innovating broadband data plans

    NASA Astrophysics Data System (ADS)

    Ha, Sangtae; Joe-Wong, Carlee; Sen, Soumya; Chiang, Mung

    2012-01-01

    Wireless Internet usage is doubling every year. Users are using more of high bandwidth data applications, and the heavy usage concentrates on several peak hours in a day, forcing ISPs to overprovision their networks accordingly. In order to remain profitable, ISPs have been using pricing as a congestion management tool. We review many of such pricing schemes in practice today and argue that they do not solve ISPs' problem of growing data traffic. We believe that dynamic, time-dependent usage pricing, which charges users based on when they access the Internet, can incentivize users to spread out their bandwidth consumption more evenly across different times of the day, thus helping ISPs to overcome the problem of peak congestion. Congestion pricing is not a new idea in itself, but the time for its implementation in data networks has finally arrived. Our key contribution lies in developing new analysis and a fully integrated system architecture, called TUBE (Time-dependent Usage-based Broadband price Engineering) that enables ISPs to implement the proposed TDP plan. The theory, simulation, and system implementation of TUBE system is further complemented with consumer surveys conducted in India and the US, along with preparations for a field trial that is currently underway.

  2. Ionomer Dynamics: Insights from Broadband Dielectric Spectroscopy

    NASA Astrophysics Data System (ADS)

    Runt, James

    2015-03-01

    Ionomers (polymers containing ionic functionality) have been traditionally used as packaging materials and in molding applications, and are now of increasing interest as candidate single ion conductors for energy storage devices, in energy conversion, and for other electroactive materials applications. The focus of this presentation is on the insight that broadband dielectric (impedance) spectroscopy brings to our understanding of ion and polymer dynamics of this family of materials. As an example of our recent work on relatively conductive ionomers, the first portion of the presentation will focus on anion conducting polyphosphazene ionomers, in which polymer bound cations are quaternized with either short alkyl or short ether oxygen chains. The low Tg, amorphous nature, and cation-solvating backbone distinguish polyphosphazenes as promising materials for ion conduction, the iodide variants being of particular interest in solar cells. In the second part of this overview, the first findings on the molecular dynamics of linear precise polyethylene-based ionomers containing 1-methylimidazolium bromide pendants on exactly every 9th, 15th, or 21st carbon atom will be summarized. In order to develop a robust interpretation of the dynamics of these materials, it is imperative to develop a thorough understanding of microphase separation (e.g. ion aggregation), and each of the above studies is complimented by multiangle X-ray scattering experiments. Supported by the NSF Polymers Program and DOE Basic Energy Sciences.

  3. Electronic resonances in broadband stimulated Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Batignani, G.; Pontecorvo, E.; Giovannetti, G.; Ferrante, C.; Fumero, G.; Scopigno, T.

    2016-01-01

    Spontaneous Raman spectroscopy is a formidable tool to probe molecular vibrations. Under electronic resonance conditions, the cross section can be selectively enhanced enabling structural sensitivity to specific chromophores and reaction centers. The addition of an ultrashort, broadband femtosecond pulse to the excitation field allows for coherent stimulation of diverse molecular vibrations. Within such a scheme, vibrational spectra are engraved onto a highly directional field, and can be heterodyne detected overwhelming fluorescence and other incoherent signals. At variance with spontaneous resonance Raman, however, interpreting the spectral information is not straightforward, due to the manifold of field interactions concurring to the third order nonlinear response. Taking as an example vibrational spectra of heme proteins excited in the Soret band, we introduce a general approach to extract the stimulated Raman excitation profiles from complex spectral lineshapes. Specifically, by a quantum treatment of the matter through density matrix description of the third order nonlinear polarization, we identify the contributions which generate the Raman bands, by taking into account for the cross section of each process.

  4. DKIST visible broadband imager data processing pipeline

    NASA Astrophysics Data System (ADS)

    Beard, Andrew; Cowan, Bruce; Ferayorni, Andrew

    2014-07-01

    The Daniel K. Inouye Solar Telescope (DKIST) Data Handling System (DHS) provides the technical framework and building blocks for developing on-summit instrument quality assurance and data reduction pipelines. The DKIST Visible Broadband Imager (VBI) is a first light instrument that alone will create two data streams with a bandwidth of 960 MB/s each. The high data rate and data volume of the VBI require near-real time processing capability for quality assurance and data reduction, and will be performed on-summit using Graphics Processing Unit (GPU) technology. The VBI data processing pipeline (DPP) is the first designed and developed using the DKIST DHS components, and therefore provides insight into the strengths and weaknesses of the framework. In this paper we lay out the design of the VBI DPP, examine how the underlying DKIST DHS components are utilized, and discuss how integration of the DHS framework with GPUs was accomplished. We present our results of the VBI DPP alpha release implementation of the calibration, frame selection reduction, and quality assurance display processing nodes.

  5. Broadband acoustic quantification of stratified turbulence.

    PubMed

    Lavery, Andone C; Geyer, W Rockwell; Scully, Malcolm E

    2013-07-01

    High-frequency broadband acoustic scattering techniques have enabled the remote, high-resolution imaging and quantification of highly salt-stratified turbulence in an estuary. Turbulent salinity spectra in the stratified shear layer have been measured acoustically and by in situ turbulence sensors. The acoustic frequencies used span 120-600 kHz, which, for the highly stratified and dynamic estuarine environment, correspond to wavenumbers in the viscous-convective subrange (500-2500 m(-1)). The acoustically measured spectral levels are in close agreement with spectral levels measured with closely co-located micro-conductivity probes. The acoustically measured spectral shapes allow discrimination between scattering dominated by turbulent salinity microstructure and suspended sediments or swim-bladdered fish, the two primary sources of scattering observed in the estuary in addition to turbulent salinity microstructure. The direct comparison of salinity spectra inferred acoustically and by the in situ turbulence sensors provides a test of both the acoustic scattering model and the quantitative skill of acoustical remote sensing of turbulence dissipation in a strongly sheared and salt-stratified estuary. PMID:23862783

  6. Broadband metasurface absorber for solar thermal applications

    NASA Astrophysics Data System (ADS)

    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. Broadband Electromagnetic Transparency by Graded Metamaterial Sphere

    NASA Astrophysics Data System (ADS)

    Sun, L.; Yu, K. W.

    2010-03-01

    We have investigated the scattering of electromagnetic waves from a radially inhomogeneous metamaterial sphere whose dielectric permittivity is described by the graded Drude model ɛs(r)=1-φp^2(r)/2̂. The radial position dependent plasma frequency depends on r as φp^2=1/2-c(r/r0)^n, where c and n are positive constants and r0 is the radius of the sphere. The electromagnetic field distribution has been calculated within the full-wave Mie scattering theory. When n=2, exact analytic solutions can be obtained in terms of confluent Heun function and confluent hypergeometric function of Kummer. This allows us to obtain the full-wave total scattering cross section analytically from the scattering field amplitudes. While the total scattering cross section Qs depends on both the graded plasma frequency profile and the frequency of the incident electromagnetic wave, it is found that Qs can achieve extremely small values over a broad frequency band and graded parameters. The analytic solutions allow us to assess the conditions for achieving broadband electromagnetic transparency in the metamaterial sphere and make tunable electromagnetic transparency feasible.

  8. Broadband linear polarization of Jupiter Trojans

    NASA Astrophysics Data System (ADS)

    Bagnulo, S.; Belskaya, I.; Stinson, A.; Christou, A.; Borisov, G. B.

    2016-01-01

    Context. 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. Aims: 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. Methods: We have obtained high-accuracy broadband 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. Results: 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. Conclusions: An extended polarimetric survey may help to further investigate the origin and the surface evolution of Jupiter Trojans.

  9. Hot Carrier Extraction with Plasmonic Broadband Absorbers.

    PubMed

    Ng, Charlene; Cadusch, Jasper J; Dligatch, Svetlana; Roberts, Ann; Davis, Timothy J; Mulvaney, Paul; Gómez, Daniel E

    2016-04-26

    Hot charge carrier extraction from metallic nanostructures is a very promising approach for applications in photocatalysis, 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 multistack layered configuration to achieve broadband, near-unit light absorption, which is spatially localized on the nanoparticle layer. We show that this enhanced light absorbance leads to ∼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 (i) the photons have energies higher than the Schottky junctions and (ii) the absorption of light is localized on the metal nanoparticles. PMID:26982625

  10. Broadband Infrared Heterodyne Spectrometer: Final Report

    SciTech Connect

    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. Absolute calibration technique for broadband ultrasonic transducers

    NASA Technical Reports Server (NTRS)

    Yost, William T. (Inventor); Cantrell, John H. (Inventor)

    1994-01-01

    Calibrating an ultrasonic transducer can be performed with a reduced number of calculations and testing. A wide-band pulser is connected to an ultrasonic transducer under test to generate ultrasonic waves in a liquid. A single frequency is transmitted to the electrostatic acoustic transducer (ESAT) and the voltage change produced is monitored. Then a broadband ultrasonic pulse is generated by the ultrasonic transducer and received by the ESAT. The output of the ESAT is amplified and input to a digitized oscilloscope for fast Fourier transform. The resulting plot is normalized with the monitored signal from the single frequency pulse. The plot is then corrected for characteristics of the membrane and diffraction effects. The transfer function of the final plot is determined. The transfer function gives the final sensitivity of the ultrasonic transducer as a function of frequency. The advantage of the system is the speed of calibrating the transducer by a reduced number of measurements and removal of the membrane and diffraction effects.

  12. Analyses of broadband noise mechanisms of rotors

    NASA Astrophysics Data System (ADS)

    George, A. R.

    The various source mechanisms which generate broadband noise on a range of rotors are reviewed. Analyses of these mechanisms are presented and compared to existing experimental data. The sources considered are load fluctuations due to inflow turbulence, due to turbulent blade boundary layers passing the trailing edge, and due to tip vortex formation turbulence. Vortex shedding noise due to laminar boundary layers and blunt trailing edges is not considered in detail as it can be avoided in most cases. Present analyses are adequate to predict the spectra from a wide variety of experiments on fans, helicopter rotors, and wind turbines to within about 5 to 10 dB. Better knowledge of the inflow turbulence improves the accuracy of the predictions. Inflow turbulence noise depends strongly on ambient conditions and dominates at low frequencies. Trailing edge and tip vortex noise are important at higher frequencies if inflow turbulence is weak. Boundary layer trailing edge noise increases slowly with angle of attack but not as rapidly as tip vortex formation noise. Tip noise can be important at high angles of attack for wide chord, square edge tips.

  13. Analyses of broadband noise mechanisms of rotors

    NASA Technical Reports Server (NTRS)

    George, A. R.

    1986-01-01

    The various source mechanisms which generate broadband noise on a range of rotors are reviewed. Analyses of these mechanisms are presented and compared to existing experimental data. The sources considered are load fluctuations due to inflow turbulence, due to turbulent blade boundary layers passing the trailing edge, and due to tip vortex formation turbulence. Vortex shedding noise due to laminar boundary layers and blunt trailing edges is not considered in detail as it can be avoided in most cases. Present analyses are adequate to predict the spectra from a wide variety of experiments on fans, helicopter rotors, and wind turbines to within about 5 to 10 dB. Better knowledge of the inflow turbulence improves the accuracy of the predictions. Inflow turbulence noise depends strongly on ambient conditions and dominates at low frequencies. Trailing edge and tip vortex noise are important at higher frequencies if inflow turbulence is weak. Boundary layer trailing edge noise increases slowly with angle of attack but not as rapidly as tip vortex formation noise. Tip noise can be important at high angles of attack for wide chord, square edge tips.

  14. Development of Submillimeter SIS Mixers and Broadband HEMT Amplifiers

    NASA Technical Reports Server (NTRS)

    Zmuidzinas, J.

    2004-01-01

    This is the final technical report for NASA grant NAG5-9493. entitled "Development of Submillimeter SIS Mixers and Broadband HEMT Amplifiers". The goal of this project was to develop and demonstrate a new generation of superconducting tunnel junction (SIS) receivers with extremely wide instantaneous (intermediate-frequency, or IF) bandwidths. of order 12 GHz. along with the wideband low-noise microwave HEMT (high electron mobility transistor) amplifiers which follow the SIS mixer. These wideband SIS/HEMT receivers would allow rapid submillimeter wavelength spectral line surveys to be carried out, for instance with the NASA airborne observatory SOFIA. and could potentially be useful for future submillimeter space missions such as SAFIR. In addition, there are potential NASA earth science applications. such as the monitoring of the distribution of chemical species in the stratosphere and troposphere using the limb-sounding technique. The overall goals of this project have been achieved: a broadband 200-300 SIS receiver was designed and constructed, and was demonstrated in the field through a test run at the Caltech Submillimeter Observatory on Mauna Kea. HI. The technical details are described in the appendices. which are primarily conference publications. but Appendix A also includes an unpublished summary of the latest results. The work on the SIS mixer design are described in the conference publications (appendices B and C). The "Supermix" software package that was developed at Caltech and used for the SIS design is also described in two conference papers, but has been substantially revised, debugged. and extended as part of the work completed for this grant. The Supermix package is made available to the community at no charge. The electromagnetic design of a radial waveguide probe similar to the one used in this work is described in a journal publication. Details of the novel fabrication procedure used for producing the SIS devices at JPL are also given in an

  15. Grain-size Distributions from Deconvolved Broadband Magnetic Susceptibility

    NASA Astrophysics Data System (ADS)

    Fukuma, K.

    2014-12-01

    A magnetic susceptibility meter with several-decade frequency band has recently made it possible to obtain superparamagnetic grain-size distributions only by room-temperature measurement. A rigorous deconvolution scheme of frequency dependence of susceptibility is already available. I have made some corrections on the deconvolution scheme and present its applications to broadband susceptibility data on loess and volcanic rocks. Deconvolution of frequency dependence of susceptibility was originally developed by Shchervakov and Fabian [2005]. Suppose an ensemble of grains distributed for two independent variables of volume (grain-size) and energy barrier. Applying alternating magnetic field with varying frequency results in differentiating grains by energy barrier - not directly by volume. Since the response function for frequency is known, deconvolution of frequency dependence of susceptibility provide a rigorous solution for the second moment of volume on the volume-energy barrier distribution. Based on a common assumption of a linear relation between volume and energy barrier, we can obtain analytical volume or grain-size distributions of superparamagnetic grains. A ZH broadband susceptibility meter comprises of two separated devices for lower (SM-100, 65 - 16kHz) and higher (SM-105, 16k - 512kHz) frequency ranges. At every frequency susceptibility calibration was conducted using three kinds of paramagnetic rare earth oxides [Fukuma and Torii, 2011]. Almost all samples exhibited seemingly linear dependences of in-phase susceptibility on logarithmic frequency. This indicates that the measured data do not suffer serious noise, and that the second moment of volume is relatively constant against energy barrier. Nonetheless, third-order polynomial fittings revealed slight deflections from the quasi-linear susceptibility - logarithmic frequency relations. Deconvolving the polynomials showed that such slight defections come from peaks or troughs in varying second moment

  16. Broadband Light Source Based on Four-Color Self-Assembled InAs Quantum Dot Ensembles Monolithically Grown in Selective Areas

    NASA Astrophysics Data System (ADS)

    Ozaki, Nobuhiko; Takeuchi, Koichi; Ohkouchi, Shunsuke; Ikeda, Naoki; Sugimoto, Yoshimasa; Asakawa, Kiyoshi; Hogg, Richard A.

    We developed advanced techniques for the growth of self-assembled quantum dots (QDs) for fabricating a broadband light source that can be applied to optical coherence tomography (OCT). Four QD ensembles and strain reducing layers (SRLs) were grown in selective areas on a wafer by the use of a 90° rotational metal mask. The SRL thickness was varied to achieve appropriate shifts in the peak wavelength of the QD emission spectrum of up to 120nm. The four-color QD ensembles were expected to have a broad bandwidth of more than 160nm due to the combination of excited state emissions when introduced in a current-induced broadband light source such as a superluminescent diode (SLD). Furthermore, a desired shape of the SLD spectrum can be obtained by controlling the injection current applied to each QD ensemble. The broadband and spectrum shape controlled light source is promising for high-resolution and low-noise OCT systems.

  17. Efficacy Analysis of a Script-based Guide for EVAR Execution: is it Possible to Reduce Patient Exposure to Contrast, Operative Time and Blood Loss even when Advanced Technologies are not Available?

    PubMed Central

    Molinari, Giovani José Dal Poggetto; Guillaumon, Ana Terezinha; Dalbem, Andréia Marques de Oliveira

    2015-01-01

    INTRODUCTION Despite the patient and medical staff exposure to radiation in endovascular aneurysm repair, the benefits of this abdominal aortic aneurysm type of surgical management are justfied by minor recovery time and hospitalization, as well as an option for patients not elected to conventional open repair. In this minimally invasive surgical aproach, time of procedure and radiation doses can be substantial - and the increasing frequency of these procedures and it's complexity have impelled vascular surgeons to face additional and successive risk to occupational radiation exposure. Meticulous study of the computed tomography angiography during the endovascular aneurysm repair preparation allows reduction of unnecessary radiation exposure, as also reduces consecutive image acquisition and contrast use (that may be related to renal overload in susceptible patients). Some studies have proposed strategies to optimize endovascular intervention to reduce contrast use and X-ray exposure. Although they might prove to be effective, they rely on use of additional specific and advanced equipment, available only in major centers. As an alternative to this expensive and restrict technology, it is presented a simpler technique through image manipulation on software OsiriX, aiming to reduce both exposures. OBJECTIVE To analyze the efficacy of the adoption of a study protocol and a script-based guide in preparation for endovascular aneurysm repair through verifying it's impact over the surgical procedure - as referred to intravascular contrast infuse, effects over renal function, blood loss and operatory time. METHODS A longitudinal prospective study from March 2014 through March 2015, where 30 performed endovascular aneurysm repair were compared to a historic control group. The planning for endovascular aneurysm repair through the patient's tomographic image manipulation in the prospective group was performed with OsiriX MD software. A script-based guide upon gathering

  18. Theoretical and experimental evaluation of broadband decoupling techniques for in vivo nuclear magnetic resonance spectroscopy.

    PubMed

    de Graaf, Robin A

    2005-06-01

    A theoretical and experimental evaluation of existing broadband decoupling methods with respect to their utility for in vivo (1)H-(13)C NMR spectroscopy is presented. Simulations are based on a modified product operator formalism, while an experimental evaluation is performed on in vitro samples and human leg and rat brain in vivo. The performance of broadband decoupling methods was evaluated with respect to the required peak and average RF powers, decoupling bandwidth, decoupling side bands, heteronuclear scalar coupling constant, and sensitivity toward B(2) inhomogeneity. In human applications only the WALTZ and MLEV decoupling methods provide adequate decoupling performance at RF power levels that satisfy the FDA guidelines on local tissue heating. For very low RF power levels (B(2max) < 300 Hz) one should verify empirically whether the experiment will benefit from broadband decoupling. At higher RF power levels acceptable for animal studies additional decoupling techniques become available and provide superior performance. Since the average RF power of adiabatic RF pulses is almost always significantly lower than the peak RF power, it can be stated that for average RF powers suitable for animal studies it is always possible to design an adiabatic decoupling scheme that outperforms all other schemes. B(2) inhomogeneity degrades the decoupling performance of all methods, but the decoupling bandwidths for WALTZ-16 and especially adiabatic methods are still satisfactory for useful in vivo decoupling with a surface coil. PMID:15906279

  19. Preliminary results from NERIES Broadband Ocean Bottom Seismometer deployment

    NASA Astrophysics Data System (ADS)

    Singh, S.; Favali, P.; Jokat, W.

    2009-04-01

    Off-shore of southern Europe is one of the most seismically active regions on the Earth. However, this region is mainly monitored using land seismic networks, leaving a large observational gap in the Mediterranean Sea and NE Atlantic. As a first step towards filling this gap, NERIES BBOBS Group (IPGP, INGV, AWI) has deployed three broadband ocean bottom seismometers (OBS) for three years, where the OBS are recovered and redeployed every year. One OBS was deployed in the Ligurian Sea (40° N, 6.5° E), between Balearic Islands and Sardinia, three in the Ionian Sea (36° N, 18° E), between Italy and Greece, and six near Azores at MOMAR site (2 W 37 N). The first year of deployment and recovery completed in August 2008 and the BBOBS have been deployed for the second year. The 2007 year has been an year of several great earthquakes (Sumatra, Kuril Island, China), which were recorded by these OBS. Our OBS also recorded hundreds of local earthquakes of magnitude >2.5 along with regional earthquakes that were not identified by land network. At the end of each year of recovery, the data will be freely available to scientific community through ORFEUS, which is a great opportunity for seismologists to use these data for region and global studies.

  20. Development of broadband antireflection of high-index substrate using SiNx/SiO2

    NASA Astrophysics Data System (ADS)

    Lim, Kim Peng; Ng, Doris K. T.; Wang, Qian

    2016-03-01

    Broadband antireflection coatings are commonly required in many silicon or III-V compound semiconductor based optoelectronic devices such as solar cells, photodetectors, and image sensors so as to enhance light conversion efficiency. Conventional approach using a single-layer antireflection coating is simple and commonly used in industry but it has a limited working bandwidth. To achieve broadband or even omni-directional characteristics, structures using thick graded refractive index (GRIN) multilayers or nanostructured surfaces which have equivalent graded refractive index profile have been proposed and demonstrated. In this paper, we will show our development of broadband antireflection for high index substrate using SiNx/SiO2 via inductively coupled plasma chemical vapour deposition (ICPCVD). Global optimization of thin-film broadband antireflection coating using adaptive simulated annealing is presented. Unlike the conventional optical coating design which uses the refractive index of available materials, the optimization approach used here decides the optimal values of the refractive index as well as the thickness of each layer. The first thin-film material optimization is carried out on the ICP-CVD machine operating at low temperature of 250°C by tuning the SiH4/N2 gas ratio. The demonstrated double layer antireflection thin film reduces the average reflectance of Si surface from ~32% to ~3.17% at normal incidence for wavelength range from 400 to 1100 nm. This optical thin-film design and material development can be extended to optical wavelength filters and integrated micro-GRIN devices.

  1. Ultrafast nonlinear photoresponse of single-wall carbon nanotubes: a broadband degenerate investigation

    NASA Astrophysics Data System (ADS)

    Xu, Shuo; Wang, Fengqiu; Zhu, Chunhui; Meng, Yafei; Liu, Yujie; Liu, Wenqing; Tang, Jingyi; Liu, Kaihui; Hu, Guohua; Howe, Richard C. T.; Hasan, Tawfique; Zhang, Rong; Shi, Yi; Xu, Yongbing

    2016-04-01

    Understanding of the fundamental photoresponse of carbon nanotubes has broad implications for various photonic and optoelectronic devices. Here, Z-scan and pump-probe spectroscopy performed across 600-2400 nm were combined to give a broadband `degenerate' mapping of the nonlinear absorption properties of single-wall carbon nanotubes (SWNTs). In contrast to the views obtained from non-degenerate techniques, sizable saturable absorption is observed from the visible to the near-infrared range, including the spectral regions between semiconducting excitonic peaks and metallic tube transitions. In addition, the broadband mapping unambiguously reveals a photobleaching to photoinduced absorption transition feature within the first semiconducting excitonic band ~2100 nm, quantitatively marking the long-wavelength cut-off for saturable absorption of the SWNTs investigated. Our findings present a much clearer physical picture of SWNTs' nonlinear absorption characteristics, and help provide updated design guidelines for SWNT based nonlinear optical devices.Understanding of the fundamental photoresponse of carbon nanotubes has broad implications for various photonic and optoelectronic devices. Here, Z-scan and pump-probe spectroscopy performed across 600-2400 nm were combined to give a broadband `degenerate' mapping of the nonlinear absorption properties of single-wall carbon nanotubes (SWNTs). In contrast to the views obtained from non-degenerate techniques, sizable saturable absorption is observed from the visible to the near-infrared range, including the spectral regions between semiconducting excitonic peaks and metallic tube transitions. In addition, the broadband mapping unambiguously reveals a photobleaching to photoinduced absorption transition feature within the first semiconducting excitonic band ~2100 nm, quantitatively marking the long-wavelength cut-off for saturable absorption of the SWNTs investigated. Our findings present a much clearer physical picture of

  2. A graphene-based broadband optical modulator

    NASA Astrophysics Data System (ADS)

    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.

  3. Developing broadband sources for optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Chen, L. R.; Kashyap, R.; Azaña, J.; Maciejko, R.; Matei, R.; Baron, J.; Nemova, G.; Chauve, J.; Bojor, L.; Beitel, D.; Saqqa, S.; Singh, K.

    2006-09-01

    Optical coherence tomography (OCT) is an emerging medical diagnostic technology for noninvasive in situ and in vivo cross-sectional morphological imaging of transparent or nontransparent biological tissues and materials on a micrometer scale. The technique uses low coherence interferometry to extract the intensity of the reflected signal as a function of penetration depth in the sample and is analogous to ultrasound except that much shorter wavelength infrared radiation is used rather than sound waves. Among the key enabling technologies for OCT systems are high-power, broadband optical sources (BBS). Such sources are required to provide large dynamic range and sensitivity, as well as very high axial resolution. In this paper, we present our ongoing work on developing BBS based on the amplified spontaneous emission (ASE) from semiconductor optical amplifiers (SOAs) and erbium-doped fiber amplifiers (EDFAs). We target sources spanning the S, C, and L bands, with milliwatts of output power and smoothly shaped output spectra. In terms of shaping the output spectra, we consider different designs of gain flattening filters based on side-tapped fiber Bragg gratings (FBGs) as well as specially apodized FBGs operating in transmission. In terms of the source development, we have developed strained multiple-quantum well SOAs and hybrid SOA-EDFA structures. In the hybrid structures, we have also investigated the possibility of exploiting the unused ASE from the SOA as a secondary input to the L-band EDFA. We have also explored techniques such as double-passing to enhance efficiency as well as gain-clamping to provide some inherent spectral flattening.

  4. Chiral Molecules Revisited by Broadband Microwave Spectroscopy

    NASA Astrophysics Data System (ADS)

    Schnell, Melanie

    2014-06-01

    Chiral molecules have fascinated chemists for more than 150 years. While their physical properties are to a very good approximation identical, the two enantiomers of a chiral molecule can have completely different (bio)chemical activities. For example, the right-handed enantiomer of carvone smells of spearmint while the left-handed one smells of caraway. In addition, the active components of many drugs are of one specific handedness, such as in the case of ibuprofen. However, in nature as well as in pharmaceutical applications, chiral molecules often exist in mixtures with other chiral molecules. The analysis of these complex mixtures to identify the molecular components, to determine which enantiomers are present, and to measure the enantiomeric excesses (ee) remains a challenging task for analytical chemistry, despite its importance for modern drug development. We present here a new method of differentiating enantiomers of chiral molecules in the gas phase based on broadband rotational spectroscopy. The phase of the acquired signal bares the signature of the enantiomer, as it depends upon the combined quantity, μ_a μ_b μ_c, which is of opposite sign between enantiomers. It thus also provides information on the absolute configuration of the particular enantiomer. Furthermore, the signal amplitude is proportional to the ee. A significant advantage of our technique is its inherent mixture compatibility due to the fingerprint-like character of rotational spectra. In this contribution, we will introduce the technique and present our latest results on chiral molecule spectroscopy and enantiomer differentiation. D. Patterson, M. Schnell, J.M. Doyle, Nature 497 (2013) 475-477 V.A. Shubert, D. Schmitz, D. Patterson, J.M. Doyle, M. Schnell, Angewandte Chemie International Edition 53 (2014) 1152-1155

  5. Broadband model-based processing for shallow ocean environments

    SciTech Connect

    Candy, J.V.; Sullivan, E.J.

    1998-07-01

    Most acoustic sources found in the ocean environment are spatially complex and broadband. In the case of shallow water propagation, these source characteristics complicate the analysis of received acoustic data considerably. A common approach to the broadband problem is to decompose the received signal into a set of narrow-band lines. This then allows the problem to be treated as a multiplicity of narrow-band problems. Here a model-based approach is developed for the processing of data received on a vertical array from a broadband source where it is assumed that the propagation is governed by the normal-mode model. The goal of the processor is to provide an enhanced (filtered) version of the pressure at the array and the modal functions. Thus a pre-processor is actually developed, since one could think of several applications for these enhanced quantities such as localization, modal estimation, etc. It is well-known that in normal-mode theory a different modal structure evolves for each temporal frequency; thus it is not surprising that the model-based solution to this problem results in a scheme that requires a {open_quotes}bank{close_quotes} of narrow-band model-based processors{emdash}each with its own underlying modal structure for the narrow frequency band it operates over. The {open_quotes}optimal{close_quotes} Bayesian solution to the broadband pressure field enhancement and modal function extraction problem is developed. It is shown how this broadband processor can be implemented (using a suboptimal scheme) in pseudo real time due to its inherent parallel structure. A set of noisy broadband data is synthesized to demonstrate how to construct the processor and achieve a minimum variance (optimal Bayesian) design. It is shown that both broadband pressure-field and modal function estimates can be extracted illustrating the feasibility of this approach. {copyright} {ital 1998 Acoustical Society of America.}

  6. An improved method to derive surface albedo from narrowband AVHRR satellite data : narrowband to broadband conversion.

    SciTech Connect

    Song, J.; Gao, W.; Environmental Research; Northern Illinois Univ.

    1999-02-01

    A method was investigated to estimate broadband surface shortwave albedo from the narrowband reflectances obtained by the Advanced Very High Resolution Radiometers (AVHRRs) on board the polar orbiting satellites. Field experiments were conducted to measure simultaneously multispectral narrowband reflectances and broadband albedo over various vegetation and soil surfaces. These data were combined to examine the behavior of narrowband-to-broadband (NTB) conversion factors for different surfaces. Many previous studies have used constant NTB conversion factors for the AVHRR data. The results from this investigation indicate that the optimal NTB conversion factors for AVHRR channels 1 and 2 have a strong dependence on the amount of green vegetation within the field of view. Two conversion factors, f1 and f2, were established to quantify, respectively, (1) the relationship between the reflectance in the narrow red wave band and the total reflectance within the whole visible subregion (0.3-0.685 m) and (2) the relationship between the reflectance in the narrow near-infrared wave band and the total reflectance within the whole near-infrared subregion (0.685-2.8 m). Values of f1 and f2, calculated from field data, correlated well with the normalized difference vegetation index (NDVI), largely because of the unique characteristics of light absorption and scattering within the red and near-infrared wave bands by green leaves. The f1-NDVI and f2-NDVI relationships developed from this study were used to infer empirical coefficients needed to estimate surface albedo from AVHRR data. The surface albedo values calculated by the new method agreed with ground-based measurements within a root-mean-square error of 0.02, which is better than other methods that use constant empirical coefficients. Testing with albedo measurements made by unmanned aerospace vehicles during a field campaign also indicates that the new method provides an improved estimate of surface albedo.

  7. Development and experiment of a broadband seismograph for deep exploration

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Lin, J.; Yang, H.; Zheng, F.; Zhang, L.; Chen, Z.

    2012-12-01

    management in ether hardware or software, the average power consumption reached 2 watts, within a high-capacity lithium battery inside, the seismograph can work 80 hours continuously. With a internal 24-bit DAC and the FPGA control logic, a series of self-test items are achieved, including: noise level, the crosstalk between channels, common mode rejection ratio, harmonic distortion, detector impedance, impulse response, the gain calibration etc. Because the instrument Integrates a WIFI module inside, the instrument status and the quality of data acquisition can be real-time monitoring via a hand-held terminals. In order to verify the reliability and validity of the instrument, a deep seismic exploration research using the instruments provided in this article carried out in a certain area, 32 broadband seismograph were placed in the 120 km-long measure line (place one at intervals of about 4 km), to record the source signal far from a few hundred kilometers away. Experimental results show that performance of analog acquisition channels of the introduced instrument could reach the international advanced level. However, the non-cable designing makes the instrument get rid of the bulky cables and fulfill the target to lighten seismic instruments, which could definitely improve working efficiency, save surveying cost and be helpful to the work in the condition of complex geographical and geological environment.

  8. Bio-inspired heterogeneous composites for broadband vibration mitigation

    NASA Astrophysics Data System (ADS)

    Chen, Yanyu; Wang, Lifeng

    2015-12-01

    Structural biological materials have developed heterogeneous and hierarchical architectures that are responsible for the outstanding performance to provide protection against environmental threats including static and dynamic loading. Inspired by this observation, this research aims to develop new material and structural concepts for broadband vibration mitigation. The proposed composite materials possess a two-layered heterogeneous architecture where both layers consist of high-volume platelet-shape reinforcements and low-volume matrix, similar to the well-known “brick and mortar” microstructure of biological composites. Using finite element method, we numerically demonstrated that broadband wave attenuation zones can be achieved by tailoring the geometric features of the heterogeneous architecture. We reveal that the resulting broadband attenuation zones are gained by directly superimposing the attenuation zones in each constituent layer. This mechanism is further confirmed by the investigation into the phonon dispersion relation of each layer. Importantly, the broadband wave attenuation capability will be maintained when the mineral platelet orientation is locally manipulated, yet a contrast between the mineral platelet concentrations of the two constituent layers is essential. The findings of this work will provide new opportunities to design heterogeneous composites for broadband vibration mitigation and impact resistance under mechanically challenging environmental conditions.

  9. Bio-inspired heterogeneous composites for broadband vibration mitigation

    PubMed Central

    Chen, Yanyu; Wang, Lifeng

    2015-01-01

    Structural biological materials have developed heterogeneous and hierarchical architectures that are responsible for the outstanding performance to provide protection against environmental threats including static and dynamic loading. Inspired by this observation, this research aims to develop new material and structural concepts for broadband vibration mitigation. The proposed composite materials possess a two-layered heterogeneous architecture where both layers consist of high-volume platelet-shape reinforcements and low-volume matrix, similar to the well-known “brick and mortar” microstructure of biological composites. Using finite element method, we numerically demonstrated that broadband wave attenuation zones can be achieved by tailoring the geometric features of the heterogeneous architecture. We reveal that the resulting broadband attenuation zones are gained by directly superimposing the attenuation zones in each constituent layer. This mechanism is further confirmed by the investigation into the phonon dispersion relation of each layer. Importantly, the broadband wave attenuation capability will be maintained when the mineral platelet orientation is locally manipulated, yet a contrast between the mineral platelet concentrations of the two constituent layers is essential. The findings of this work will provide new opportunities to design heterogeneous composites for broadband vibration mitigation and impact resistance under mechanically challenging environmental conditions. PMID:26642932

  10. The Prediction of Scattered Broadband Shock-Associated Noise

    NASA Technical Reports Server (NTRS)

    Miller, Steven A. E.

    2015-01-01

    A mathematical model is developed for the prediction of scattered broadband shock-associated noise. Model arguments are dependent on the vector Green's function of the linearized Euler equations, steady Reynolds-averaged Navier-Stokes solutions, and the two-point cross-correlation of the equivalent source. The equivalent source is dependent on steady Reynolds-averaged Navier-Stokes solutions of the jet flow, that capture the nozzle geometry and airframe surface. Contours of the time-averaged streamwise velocity component and turbulent kinetic energy are examined with varying airframe position relative to the nozzle exit. Propagation effects are incorporated by approximating the vector Green's function of the linearized Euler equations. This approximation involves the use of ray theory and an assumption that broadband shock-associated noise is relatively unaffected by the refraction of the jet shear layer. A non-dimensional parameter is proposed that quantifies the changes of the broadband shock-associated noise source with varying jet operating condition and airframe position. Scattered broadband shock-associated noise possesses a second set of broadband lobes that are due to the effect of scattering. Presented predictions demonstrate relatively good agreement compared to a wide variety of measurements.

  11. Mid- and Long-IR Broadband Quantum Well Photodetector

    NASA Technical Reports Server (NTRS)

    Soibel, Alexander; Ting, David Z.; Khoshakhlagh, Arezou; Gunapala, Sarath D.

    2012-01-01

    A single-stack broadband quantum well infrared photodetector (QWIP) has been developed that consists of stacked layers of GaAs/AlGaAs quantum wells with absorption peaks centered at various wavelengths spanning across the 9- to-11- m spectral regions. The correct design of broadband QWIPs was a critical step in this task because the earlier implementation of broadband QWIPs suffered from a tuning of spectral response curve with an applied bias. Here, a new QWIP design has been developed to overcome the spectral tuning with voltage that results from non-uniformity and bias variation of the electrical field across the detector stacks with different absorption wavelengths. In this design, a special effort has been made to avoid non-uniformity and bias tuning by changing the doping levels in detector stacks to compensate for variation of dark current generation rate across the stacks with different absorption wavelengths. Single-pixel photodetectors were grown, fabricated, and tested using this new design. The measured dark current is comparable with the dark measured current for single-color QWIP detectors with similar cutoff wavelength, thus indicating high material quality as well as absence of performance degradation resulting from broadband design. The measured spectra clearly demonstrate that the developed detectors cover the desired special range of 8 to 12 m. Moreover, the shape of the spectral curves does not change with applied biases, thus overcoming the problem plaguing previous designs of broadband QWIPs.

  12. System and method for detection of dispersed broadband signals

    DOEpatents

    Qian, S.; Dunham, M.E.

    1999-06-08

    A system and method for detecting the presence of dispersed broadband signals in real time are disclosed. The present invention utilizes a bank of matched filters for detecting the received dispersed broadband signals. Each matched filter uses a respective robust time template that has been designed to approximate the dispersed broadband signals of interest, and each time template varies across a spectrum of possible dispersed broadband signal time templates. The received dispersed broadband signal x(t) is received by each of the matched filters, and if one or more matches occurs, then the received data is determined to have signal data of interest. This signal data can then be analyzed and/or transmitted to Earth for analysis, as desired. The system and method of the present invention will prove extremely useful in many fields, including satellite communications, plasma physics, and interstellar research. The varying time templates used in the bank of matched filters are determined as follows. The robust time domain template is assumed to take the form w(t)=A(t)cos[l brace]2[phi](t)[r brace]. Since the instantaneous frequency f(t) is known to be equal to the derivative of the phase [phi](t), the trajectory of a joint time-frequency representation of x(t) is used as an approximation of [phi][prime](t). 10 figs.

  13. System and method for detection of dispersed broadband signals

    DOEpatents

    Qian, Shie; Dunham, Mark E.

    1999-06-08

    A system and method for detecting the presence of dispersed broadband signals in real time. The present invention utilizes a bank of matched filters for detecting the received dispersed broadband signals. Each matched filter uses a respective robust time template that has been designed to approximate the dispersed broadband signals of interest, and each time template varies across a spectrum of possible dispersed broadband signal time templates. The received dispersed broadband signal x(t) is received by each of the matched filters, and if one or more matches occurs, then the received data is determined to have signal data of interest. This signal data can then be analyzed and/or transmitted to Earth for analysis, as desired. The system and method of the present invention will prove extremely useful in many fields, including satellite communications, plasma physics, and interstellar research. The varying time templates used in the bank of matched filters are determined as follows. The robust time domain template is assumed to take the form w(t)=A(t)cos{2.phi.(t)}. Since the instantaneous frequency f(t) is known to be equal to the derivative of the phase .phi.(t), the trajectory of a joint time-frequency representation of x(t) is used as an approximation of .phi.'(t).

  14. Broadband Access Network Planning Optimization Considering Real Copper Cable Lengths

    NASA Astrophysics Data System (ADS)

    Peternel, Blaž Kos, Andrej

    Broadband access network planning strategies with techno-economic calculations are important topics, when optimal broadband network deployments are considered. This paper analyzes optimal deployment combination of digital subscriber line technologies (xDSL) and fiber to the home technologies (FTTx), following different user bandwidth demand scenarios. For this reason, optimal placement of remote digital subscriber line multiplexer (RDSLAM) is examined. Furthermore, the article also discusses the economy of investments, depending on certain investment threshold and the reach of different xDSL technologies. Finally, the difference between broadband network deployment in a characteristic urban and rural area in Republic of Slovenia, in terms of required optical cable dig length per household is shown. A tree structure network model of a traditional copper access network is introduced. A dynamic programming logic, with recursion as a basis of a tree structure examination and evaluation of optimal network elements placement is used. The tree structure network model considers several real network parameters (e. g.: copper cable lengths, user coordinates, node coordinates). The main input for the optimization is a local loop distance between each user and a candidate node for RDSLAM placement. Modelling of copper access networks with a tree structure makes new extensions in planning optimization of broadband access networks. Optimization of network elements placement has direct influence on efficiency and profitability of broadband access telecommunication networks.

  15. Broadband Observations of High Redshift Blazars

    NASA Astrophysics Data System (ADS)

    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.

  16. Geyser's Eruptive Activity in Broadband Seismic Records

    NASA Astrophysics Data System (ADS)

    Kugaenko, Yulia; Saltykov, Vadim

    2010-05-01

    A geyser is a spring characterized by intermittent discharge of water ejected turbulently and accompanied by a vapor phase (steam). The formation of geysers is due to particular hydrogeological conditions, which exist in only a few places on Earth, so they are a fairly rare phenomenon. The reasons of geyser periodicity and specifics of the activity for every particular geyser are not completely clear yet. So almost for all known geysers it is necessary to develop the personal model. In given study we first use seismic method for detection of possible hidden feature of geyser's eruptive activity in Kamchatkan Valley of the Geysers. Broadband seismic records of geyser generated signals were obtained in hydrothermal field. The Valley of the Geysers belongs to Kronotskiy State Natural Biosphere Reserve and the UNESCO World Natural Heritage Site "Volcanoes of Kamchatka". Neither seismological nor geophysical investigations were carried out here earlier. In September, 2009 seismic observation was organized in geyser's field by 24-bit digital output broadband seismometers (GURALP CMG-6TD flat velocity response 0.033-50 Hz). Four geysers were surveyed: the fountain type Big and Giant geysers; the cone type Pearl geyser and the short-period Gap geyser. Seismometers were set as possible close to the geyser's surface vent (usually at the distance near 3-5 m). Main parameters of the eruptions for the investigated geysers: - The Giant geyser is the most powerful among the regular active geysers in Kamchatkan Valley of the Geysers. The height of the fountain reaches 30 meters, the mass of water erupted is about 40-60 tons. The main cycle of activity varies significantly: in 1945 the intervals between eruptions was near 3 hours, nowadays it is 5-6 hours. As a geyser of fountain type, the Giant geyser erupts from the 2*3 m2 pool of water. - The Big geyser was flooded by the lake after the natural catastrophe (giant mud-stone avalanche, formed by landslide, bed into Geiyzernaya

  17. Geyser's Eruptive Activity in Broadband Seismic Records

    NASA Astrophysics Data System (ADS)

    Kugaenko, Yulia; Saltykov, Vadim

    2010-05-01

    A geyser is a spring characterized by intermittent discharge of water ejected turbulently and accompanied by a vapor phase (steam). The formation of geysers is due to particular hydrogeological conditions, which exist in only a few places on Earth, so they are a fairly rare phenomenon. The reasons of geyser periodicity and specifics of the activity for every particular geyser are not completely clear yet. So almost for all known geysers it is necessary to develop the personal model. In given study we first use seismic method for detection of possible hidden feature of geyser's eruptive activity in Kamchatkan Valley of the Geysers. Broadband seismic records of geyser generated signals were obtained in hydrothermal field. The Valley of the Geysers belongs to Kronotskiy State Natural Biosphere Reserve and the UNESCO World Natural Heritage Site "Volcanoes of Kamchatka". Neither seismological nor geophysical investigations were carried out here earlier. In September, 2009 seismic observation was organized in geyser's field by 24-bit digital output broadband seismometers (GURALP CMG-6TD flat velocity response 0.033-50 Hz). Four geysers were surveyed: the fountain type Big and Giant geysers; the cone type Pearl geyser and the short-period Gap geyser. Seismometers were set as possible close to the geyser's surface vent (usually at the distance near 3-5 m). Main parameters of the eruptions for the investigated geysers: - The Giant geyser is the most powerful among the regular active geysers in Kamchatkan Valley of the Geysers. The height of the fountain reaches 30 meters, the mass of water erupted is about 40-60 tons. The main cycle of activity varies significantly: in 1945 the intervals between eruptions was near 3 hours, nowadays it is 5-6 hours. As a geyser of fountain type, the Giant geyser erupts from the 2*3 m2 pool of water. - The Big geyser was flooded by the lake after the natural catastrophe (giant mud-stone avalanche, formed by landslide, bed into Geiyzernaya

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

    SciTech Connect

    Hyun, Jerome K.; Ahn, Chi Won; Kim, Woo Choong; Kim, Tae Hyun; Hyun, Moon Seop; Kim, Hee Yeoun E-mail: jhpark@nnfc.re.kr; Park, Jae Hong E-mail: jhpark@nnfc.re.kr; Lee, Won-Oh

    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%.

  19. Piezomagnetoelastic broadband energy harvester: Nonlinear modeling and characterization

    NASA Astrophysics Data System (ADS)

    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.

  20. Broadband unidirectional cloaks based on flat metasurface focusing lenses

    NASA Astrophysics Data System (ADS)

    Li, Yongfeng; Zhang, Jieqiu; Qu, Shaobo; Wang, Jiafu; Pang, Yongqiang; Xu, Zhuo; Zhang, Anxue

    2015-08-01

    Bandwidth extension and thickness reduction are now the two key issues of cloaks. In this paper, we propose to achieve broadband, thin uni-directional electromagnetic (EM) cloaks using metasurfaces. To this end, a wideband flat focusing lens is firstly devised based on high-efficiency transmissive metasurfaces. Due to the nearly dispersionless parabolic phase profile along the metasurface in the operating band, incident plane waves can be focused efficiently after passing through the metasurface. Broadband unidirectional EM cloaks were then designed by combining two identical flat lenses. Upon illumination, the incident plane waves are firstly focused by one lens and then are restored by the other lens, avoiding the cloaked region. Both simulation and experiment results verify the broadband unidirectional cloak. The broad bandwidth and small thickness of such cloaks have potential applications in achieving invisibility for electrically large objects.

  1. Inferring surface solar absorption from broadband satellite measurements

    NASA Technical Reports Server (NTRS)

    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.

  2. Photo-excited broadband tunable terahertz metamaterial absorber

    NASA Astrophysics Data System (ADS)

    Zhang, Jianna; Wang, Guocui; Zhang, Bo; He, Ting; He, Yanan; Shen, Jingling

    2016-04-01

    We demonstrate a photo-excited broadband tunable metamaterial absorber for use in the terahertz region. The metamaterial absorber consists of a hybrid metal-semiconductor square split ring and a metallic ground plane that are separated by a dielectric resonator spacer. The conductivity of the silicon used to fill the gap in the metallic resonator is tuned actively as a function of the incident pump power, which results in frequency modulation of the resonance absorption peak. Broadband tunable metamaterial absorbers are produced by suitable placement of the photoconductive silicon in different critical regions of the metallic resonator. In addition, the proposed method is applicable to a concentric rings-based metallic resonator. The proposed photo-excited broadband tunable metamaterial absorber has numerous potential applications, including uses as terahertz modulators and switches.

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

    PubMed

    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

  4. Broadband spatiotemporal Gaussian Schell-model pulse trains.

    PubMed

    Dutta, Rahul; Korhonen, Minna; Friberg, Ari T; Genty, Göery; Turunen, Jari

    2014-03-01

    A new class of partially coherent model sources is introduced on the basis of the second-order coherence theory of nonstationary optical fields. These model sources are spatially fully coherent at each frequency but can have broadband spectra and variable spectral coherence properties, which lead to reduced spatiotemporal coherence in the time domain. The source model is motivated by the spectral coherence properties of supercontinuum pulse trains generated in single-spatial-mode optical fibers. We demonstrate that such broadband light is highly (but not completely) spatially coherent, even though the spectral and temporal coherence properties may vary over a wide range. The model sources introduced here are convenient in assessing the spatiotemporal coherence of broadband pulses in optical systems. PMID:24690663

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

    NASA Astrophysics Data System (ADS)

    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.

  6. Source localization for active control of turbofan rotor-stator broadband noise

    NASA Astrophysics Data System (ADS)

    Walker, Bruce E.

    2005-09-01

    In order to identify a reference signal source for an active noise cancellation system, cross-correlation techniques were used to localize broadband noise source regions on exit guide vanes of the NASA Glenn Research Center Advance Noise Control Fan (ANCF). Arrays of surface pressure sensors were imbedded in one guide vane and in the wall of the fan. Synchronous sampling was used with a multichannel data acquisition system to allow removal of periodic components from the signals. The signals were then cross-correlated to assess radiation directivity and the relationship between vane surface pressure and in-duct acoustic noise. The results of these measurements indicated that broadband unsteady pressures near the leading edge tip of the guide vane were well enough correlated with acoustic radiation that 2-3 dB active noise cancellation could be achieved using a simple gain-delay control algorithm and actuator array. After successful simulation in a wind tunnel environment the concept was incorporated on 15 guide vanes and tested in ANCF. Cross-correlation measurements were further used to evaluate system performance and to identify competing noises from rotating and stationary sources within the fan.

  7. The new Hamburg Broadband Oceanbottom Seismometer: experiences from a longterm-deployment in the Tyrrhenian Sea

    NASA Astrophysics Data System (ADS)

    Dahm, T.; Herber, R.; Thorwart, M.

    2001-12-01

    Since winter 2000 the Geophysical Institute of the University of Hamburg, Germany, has developed 4 new broadband free-fall oceanbottom stations which are available for longterm experiments in oceanbottom seismology. The modular system consists of a flat and broad frame and anchor, holding commercially available components as datalogger (Send-MLS, < 200 sps, 24 bit), releaser (Mors-Oceano), sensors (PMD Scientific 21233m LP seismometer and E-2PD hydrophone), and location tools (Novatec flashlight and radio antenna). The broadband sensor is mounted into a passively gravity-levelled oil-damped gimbal in one of the four buoyancy glass-spheres (17''), which itself is fixed in close contact to the anchor of the station. The station can be alternatively equipped with a 4.5 Hz sensor hosted in an external pack and a SEND-MBS datalogger, for use in high-frequency seismics. The frame and anchor is designed to have a good coupling to ground below 10 Hz and a low sensitivity to flow and differential-motion induced tilt. Two pressure tubes are available for the data-acquisition system, the power, and possible additional equipment. The maximal deployment depth is 6000 m. It is possible to continously record 4 channels with 50 sps for one year. A first 6-month deployment has been in the Tyrrhenian Sea, within a cooperational project with GEOMAR, Kiel, and GEOSTAR of INGV, Rome, in order to study teleseismic phases and the local seismicity from the Ionian slab and the Aeolian Island volcanic chain. Several M>7 events have been recorded. The Hamburg stations show, in most cases, low tilt-noise and high-quality teleseismic and local recordings, also on the horizontal components, indicating a good coupling in the frequency range of interest. We found that the compact and simple design of the free-fall station is well suited for oceanbottom broadband seismology.

  8. Design and implementation of super broadband high speed waveguide switches

    NASA Astrophysics Data System (ADS)

    Zhu, Wenbin; Chao, Ju-Hung; Wang, Chao; Yao, Jimmy; Yin, Stuart

    2015-08-01

    In this paper, based on the theory of dynamic waveguiding effect in nanodisordered KTN crystals, a detailed design and implementation of a super broadband 1x2 high speed waveguide switch is presented. The important waveguide parameters, including the dimension, the refractive index distribution, and the electric field distribution within the waveguide are quantitatively simulated and analyzed. An experimental verification of switching effect based on the design is also conducted, which confirmed the design. The broadband and high speed nature of such kind of switch can play a key role in data center networks and cloud computing, which needs low power consumption and high speed switches.

  9. Realization of a broadband electromagnetic gateway at microwave frequencies

    NASA Astrophysics Data System (ADS)

    Bai, Guo Dong; Yang, Fan; Jiang, Wei Xiang; Mei, Zhong Lei; Cui, Tie Jun

    2015-10-01

    We propose and experimentally demonstrate a broadband illusion device—"electromagnetic gateway" at microwave frequencies. The device is first realized using crossed split-ring resonator and wire unit cells, which can provide the desirable double-negative parameters through fine geometrical designs. Taking into account the complexities in practical realization, we then simplify the original design by using only half of the unit cells. Both simulation and experimental results verify the good abilities of the simplified gateway device in broadband in microwave frequencies.

  10. Sensitive, time-resolved, broadband spectroscopy of single transient processes

    NASA Astrophysics Data System (ADS)

    Fjodorow, Peter; Baev, Ivan; Hellmig, Ortwin; Sengstock, Klaus; Baev, Valery M.

    2015-09-01

    Intracavity absorption spectroscopy with a broadband Er3+-doped fiber laser is applied to time-resolved measurements of transient gain and absorption in electrically excited Xe and Kr plasmas. The achieved time resolution for broadband spectral recording of a single process is 25 µs. For pulsed-periodic processes, the time resolution is limited by the laser pulse duration, which is set here to 3 µs. This pulse duration also predefines the effective absorption path length, which amounts to 900 m. The presented technique can be applied to multicomponent analysis of single transient processes such as shock tube experiments, pulse detonation engines, or explosives.

  11. A piezoelectric bistable plate for nonlinear broadband energy harvesting

    NASA Astrophysics Data System (ADS)

    Arrieta, A. F.; Hagedorn, P.; Erturk, A.; Inman, D. J.

    2010-09-01

    Recently, the idea of using nonlinearity to enhance the performance of vibration-based energy harvesters has been investigated. Nonlinear energy harvesting devices have been shown to be capable of operating over wider frequency ranges delivering more power than their linear counterparts, rendering them more suitable for real applications. In this paper, we propose to exploit the rich nonlinear behavior of a bistable composite plate with bonded piezoelectric patches for broadband nonlinear energy harvesting. The response of the structure is experimentally investigated revealing different large amplitude oscillations. Substantially large power is extracted over a wide frequency range achieving broadband nonlinear energy harvesting.

  12. Broadband sound blocking in phononic crystals with rotationally symmetric inclusions.

    PubMed

    Lee, Joong Seok; Yoo, Sungmin; Ahn, Young Kwan; Kim, Yoon Young

    2015-09-01

    This paper investigates the feasibility of broadband sound blocking with rotationally symmetric extensible inclusions introduced in phononic crystals. By varying the size of four equally shaped inclusions gradually, the phononic crystal experiences remarkable changes in its band-stop properties, such as shifting/widening of multiple Bragg bandgaps and evolution to resonance gaps. Necessary extensions of the inclusions to block sound effectively can be determined for given incident frequencies by evaluating power transmission characteristics. By arraying finite dissimilar unit cells, the resulting phononic crystal exhibits broadband sound blocking from combinational effects of multiple Bragg scattering and local resonances even with small-numbered cells. PMID:26428816

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

    PubMed

    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

  14. Crosstalk analysis of a broadband data communications system

    SciTech Connect

    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.

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

    PubMed

    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

  16. Experimental demonstration of quantum teleportation of broadband squeezing.

    PubMed

    Yonezawa, Hidehiro; Braunstein, Samuel L; Furusawa, Akira

    2007-09-14

    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+/-0.2 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 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. PMID:17930422

  17. Combless broadband terahertz generation with conventional laser diodes.

    PubMed

    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. PMID:21445166

  18. Compact solar autoclave based on steam generation using broadband light-harvesting nanoparticles

    PubMed Central

    Neumann, Oara; Feronti, Curtis; Neumann, Albert D.; Dong, Anjie; Schell, Kevin; Lu, Benjamin; Kim, Eric; Quinn, Mary; Thompson, Shea; Grady, Nathaniel; Nordlander, Peter; Oden, Maria; Halas, Naomi J.

    2013-01-01

    The lack of readily available sterilization processes for medicine and dentistry practices in the developing world is a major risk factor for the propagation of disease. Modern medical facilities in the developed world often use autoclave systems to sterilize medical instruments and equipment and process waste that could contain harmful contagions. Here, we show the use of broadband light-absorbing nanoparticles as solar photothermal heaters, which generate high-temperature steam for a standalone, efficient solar autoclave useful for sanitation of instruments or materials in resource-limited, remote locations. Sterilization was verified using a standard Geobacillus stearothermophilus-based biological indicator. PMID:23836642

  19. Compact solar autoclave based on steam generation using broadband light-harvesting nanoparticles.

    PubMed

    Neumann, Oara; Feronti, Curtis; Neumann, Albert D; Dong, Anjie; Schell, Kevin; Lu, Benjamin; Kim, Eric; Quinn, Mary; Thompson, Shea; Grady, Nathaniel; Nordlander, Peter; Oden, Maria; Halas, Naomi J

    2013-07-16

    The lack of readily available sterilization processes for medicine and dentistry practices in the developing world is a major risk factor for the propagation of disease. Modern medical facilities in the developed world often use autoclave systems to sterilize medical instruments and equipment and process waste that could contain harmful contagions. Here, we show the use of broadband light-absorbing nanoparticles as solar photothermal heaters, which generate high-temperature steam for a standalone, efficient solar autoclave useful for sanitation of instruments or materials in resource-limited, remote locations. Sterilization was verified using a standard Geobacillus stearothermophilus-based biological indicator. PMID:23836642

  20. Assessing Quality of Experience while comparing competing mobile broadband services from the user perspective

    NASA Astrophysics Data System (ADS)

    Madruga, Ewerton L.; David, Rodrigo; Sabóia de Souza, Rodolfo; Dantas, Romulo

    2015-01-01

    The growth of mobile traffic is exploding globally, and users can already choose their best smartphone or tablet options from a handful of manufacturers based on specific criteria such as price and usability. It is much less clear when the user needs to pick from various mobile broadband service providers when choices are available. After all, how does one know what is the best provider for a given usage profile? This work uses drive tests to investigate the variation of radio frequency conditions and relate them to the quality of experience from the viewpoint of the user.

  1. Broadband networks for interactive telemedical applications

    NASA Astrophysics Data System (ADS)

    Graschew, Georgi; Roelofs, Theo A.; Rakowsky, Stefan; Schlag, Peter M.

    2002-08-01

    Using off-the-shelf hardware components and a specially developed high-end software communication system (WinVicos) satellite networks for interactive telemedicine have been designed and developed. These networks allow for various telemedical applications, like intraoperative teleconsultation, second opinioning, teleteaching, telementoring, etc.. Based on the successful GALENOS network, several projects are currently being realized: MEDASHIP (Medical Assistance for Ships); DELTASS (Disaster Emergency Logistic Telemedicine Advanced Satellites Systems) and EMISPHER (Euro-Mediterranean Internet-Satellite Platform for Health, medical Education and Research).

  2. Free-space optical technology and distribution architecture for broadband metro and local services

    NASA Astrophysics Data System (ADS)

    Dodley, J. P.; Britz, David M.; Bowen, D. J.; Lundgren, Carl W.

    2001-02-01

    12 This paper addresses the hardware and operational requirements for broadband metro and local services using line of sight wireless Free Space Optical Communication (FSOC) optical links. The primary considerations for successful optical wireless service provisions include link availability, type of service and integration into existing fiber optic networks. A comprehensive link analysis for broadband access services is presented. This paper addresses FSOC critical atmospheric transmission impairments and describes one possible FSOC/network fiber optic interface and routing scenario. This paper will also detail methods to restor FSOC service links that have failed due to atmospheric impairments. This paper will detail the use of secondary radio (mm wave or ISM band radio) link architectures to provide critical transmission back-up for data, emergency and voice call services. An FSOC back-up link for existing millimeter-wave radio local services is also discussed. A co-operative network of FSOC links is discussed for achieving availability requirements for metro and local distribution services. This paper also describes one possible rooftop routing scenario using optical cross- connect architectures located at each node of the local FSOC access network. Rooftop routing will utilize the technology flexibility and system redundancy described above to provide high `five nines' metro service availability. This paper will also describe a proposed FSOC test installation to study link architectures, performance of such links, and vendor product interface and evaluation.

  3. NASA's K/Ka-Band Broadband Aeronautical Terminal for Duplex Satellite Video Communications

    NASA Technical Reports Server (NTRS)

    Densmore, A.; Agan, M.

    1994-01-01

    JPL has recently begun the development of a Broadband Aeronautical 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). The BAT system will provide the systems and technology groundwork for an eventual commercial K/Ka-band aeronautical satellite communication system. With industry/government partnerships, three main goals will be addressed by the BAT task: 1) develop, characterize and demonstrate the performance of an ACTS based high data rate aeronautical communications system; 2) assess the performance of current video compression algorithms in an aeronautical satellite communication link; and 3) characterize the propagation effects of the K/Ka-band channel for aeronautical communications.

  4. Libraries Use Broadband Internet Service to Serve High Need Communities. Data Note. Number 1

    ERIC Educational Resources Information Center

    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…

  5. 76 FR 51271 - Implementing a Nationwide, Broadband, Interoperable Public Safety Network in the 700 MHz Band

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-18

    ... COMMISSION 47 CFR Part 90 Implementing a Nationwide, Broadband, Interoperable Public Safety Network in the... interoperable public safety broadband network. The establishment of a common air interface for 700 MHz public safety broadband networks will create a foundation for interoperability and provide a clear path for...

  6. Model-based processing for shallow ocean environments: The broadband problem

    SciTech Connect

    Candy, J.V.; Sullivan, E.J.

    1996-01-31

    Most acoustic sources found is the ocean environmental are spatially complex and broadband. When propagating in a shallow ocean these source characteristics complicate the analysis of received acoustic data considerably. The enhancement of broadband acoustic pressure- field measurements using a vertical array is discussed. Here a model- based approach is developed for a broadband source using a normal- mode propagation model.

  7. The Evolution of South Korea's Broadband Convergence Network, 2004-2007

    ERIC Educational Resources Information Center

    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…

  8. 76 FR 44495 - A National Broadband Plan for Our Future; Petition for Reconsideration

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-26

    ... COMMISSION 47 CFR Chapter I A National Broadband Plan for Our Future; Petition for Reconsideration AGENCY... proceeding concerning a ] national broadband plan for our future and published pursuant to 47 CFR 1.429(e... Matter of Implementation of Section 224 of the Act (WC Docket No. 07-245); A National Broadband Plan...

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

  11. Electronic systems for transverse coupled-bunch feedback in the Advanced Light Source (ALS)

    SciTech Connect

    Barry, W.; Lambertson, G.R.; Lo, C.C.

    1993-10-01

    In order to effectively control a large number of transverse coupled-bunch modes in the LBL Advanced Light Source (ALS) storage ring, a broad-band, bunch-by-bunch feedback system has been designed, and is beginning to undergo testing and commissioning. This paper addresses, in some detail, the major electronic components of the feedback system. In particular, the components described include: broad-band microwave position detection receivers, closed orbit offset signal rejection circuitry, and baseband quadrature processing circuitry.

  12. 76 FR 26620 - A National Broadband Plan for Our Future

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-09

    ...In this document, the Commission revises its pole attachment rules to promote competition and to reduce the potentially excessive costs of deploying telecommunications, cable, and broadband networks. The Commission also revises the telecommunications rate formula for pole attachments consistent with the statutory framework, reinterprets the Communications Act of 1934, as amended, to allow......

  13. 47 CFR 90.1403 - Public safety broadband license conditions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... responsibilities of the Public Safety Broadband Licensee shall include the following: (1) Negotiation of the NSA... the 763-768 MHz and 793-798 MHz bands, within the technical and operational confines of the NSA. (4... equipment and applications. (5) Sole authority, which cannot be waived in the NSA, to approve,...

  14. 47 CFR 90.1403 - Public safety broadband license conditions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... responsibilities of the Public Safety Broadband Licensee shall include the following: (1) Negotiation of the NSA... the 763-768 MHz and 793-798 MHz bands, within the technical and operational confines of the NSA. (4... equipment and applications. (5) Sole authority, which cannot be waived in the NSA, to approve,...

  15. 75 FR 36071 - Framework for Broadband Internet Service

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-24

    ...This document begins an open, public process to consider the adequacy of the current legal framework within which the Commission promotes investment and innovation in, and protects consumers of, broadband Internet service. Recent developments--including a decision of the United States Court of Appeals for the District of Columbia Circuit and affirmation from Congress that the Commission plays......

  16. Broadband antireflective surface-relief structure for THz optics.

    PubMed

    Brückner, Claudia; Pradarutti, Boris; Stenzel, Olaf; Steinkopf, Ralf; Riehemann, Stefan; Notni, Gunther; Tünnermann, Andreas

    2007-02-01

    The requirements for a broadband antireflective structure in the THz spectral region are derived. Optimized structural parameters for a surface-relief grating adapted to the spectrum of an intended THz pulse are deduced. The effect of a structure fabricated into Topas((R)) by a single-point diamond-turning process is demonstrated. PMID:19532301

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

    NASA Astrophysics Data System (ADS)

    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.

  18. Cable Communications Revolution. Future: Broadband Communications, Local Origination.

    ERIC Educational Resources Information Center

    Peters, Robert W.

    The revolution in two-way broadband communications envisioned for the future includes remote access to libraries, interactive educational programing, shopping at home, personal and property security, and many other services limited only by man's imagination and his ability to deliver the service at a price the consumer is willing and able to pay.…

  19. Novel broadband glass phosphors for high CRI WLEDs.

    PubMed

    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

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

    ERIC Educational Resources Information Center

    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. The Glenview Model: Community Networking via Broadband Cable.

    ERIC Educational Resources Information Center

    Mundt, John P.

    This paper describes the installation of a data network in the community of Glenview, Illinois, which uses broadband cable equipment to connect schools, libraries, and governmental agencies to each other and to the Internet via a high speed Ethernet network. The history of the project is outlined followed by a discussion of the implementation of…

  2. A stochastic approach to robust broadband structural control

    NASA Technical Reports Server (NTRS)

    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.

  3. Broadband-ISDN: Personal Connections to Global Resources.

    ERIC Educational Resources Information Center

    Kaman, Geradine M.

    1993-01-01

    Discusses the development and impact of broadband ISDN (Integrated Services Digital Network) on global telecommunications and society. Issues covered include regulatory policies, ownership and control, content regulation, home access, rural versus urban access, pricing, user groups, barriers, and privacy. The need for greater public involvement is…

  4. Methods and devices for generation of broadband pulsed radiation

    DOEpatents

    Borguet, Eric; Isaienko, Oleksandr

    2013-05-14

    Methods and apparatus for non-collinear optical parametric ampliffication (NOPA) are provided. Broadband phase matching is achieved with a non-collinear geometry and a divergent signal seed to provide bandwidth gain. A chirp may be introduced into the pump pulse such that the white light seed is amplified in a broad spectral region.

  5. Broadband enhanced transmission of acoustic waves through serrated metal gratings

    NASA Astrophysics Data System (ADS)

    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).

  6. A planar broad-band flared microstrip slot antenna

    NASA Astrophysics Data System (ADS)

    Povinelli, Mark J.

    1987-08-01

    Experimental results have been obtained on a planar multioctave bandwidth flared microstrip slot. When crossed, the element is capable of horizontal, vertical, or circular polarization. A design was fabricated and measurements were taken to define the performance. The input impedance and radiation characteristics are shown to have a broad-band response when configured as a cavity-backed element.

  7. 47 CFR 90.1403 - Public safety broadband license conditions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... responsibilities of the Public Safety Broadband Licensee shall include the following: (1) Negotiation of the NSA... the 763-768 MHz and 793-798 MHz bands, within the technical and operational confines of the NSA. (4... equipment and applications. (5) Sole authority, which cannot be waived in the NSA, to approve,...

  8. Global Interoperability of Broadband Networks (GIBN): Project Overview

    NASA Technical Reports Server (NTRS)

    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.

  9. Analysis of broadband seismograms from selected IASPEI events

    USGS Publications Warehouse

    Choy, G.L.; Engdahl, E.R.

    1987-01-01

    Broadband seismograms of body waves that are flat to displacement and velocity in the frequency range from 0.01 to 5.0 Hz can now be routinely obtained for most earthquakes of magnitude greater than about 5.5. These records are obtained either directly or through multichannel deconvolution of waveforms from digitally recording seismograph stations. In contrast to data from conventional narrowband seismographs, broadband records have sufficient frequency content to define the source-time functions of body waves, even for shallow events for which the source functions of direct and surface-reflected phases may overlap. Broadband seismograms for selected IASPEI events are systematically analysed to identify depth phases and the presence of subevents. The procedure results in improved estimates of focal depth, identification of subevents in complex earthquakes, and better resolution of focal mechanisms. We propose that it is now possible for reporting agencies, such as the National Earthquake Information Center, to use broadband digital waveforms routinely in the processing of earthquake data. ?? 1987.

  10. Ultra-broadband light trapping using nanotextured decoupled graphene multilayers

    PubMed Central

    Anguita, José V.; Ahmad, Muhammad; Haq, Sajad; Allam, Jeremy; Silva, S. Ravi P.

    2016-01-01

    The ability to engineer a thin two-dimensional surface for light trapping across an ultra-broad spectral range is central for an increasing number of applications including energy, optoelectronics, and spectroscopy. Although broadband light trapping has been obtained in tall structures of carbon nanotubes with millimeter-tall dimensions, obtaining such broadband light–trapping behavior from nanometer-scale absorbers remains elusive. We report a method for trapping the optical field coincident with few-layer decoupled graphene using field localization within a disordered distribution of subwavelength-sized nanotexturing metal particles. We show that the combination of the broadband light–coupling effect from the disordered nanotexture combined with the natural thinness and remarkably high and wavelength-independent absorption of graphene results in an ultrathin (15 nm thin) yet ultra-broadband blackbody absorber, featuring 99% absorption spanning from the mid-infrared to the ultraviolet. We demonstrate the utility of our approach to produce the blackbody absorber on delicate opto-microelectromechanical infrared emitters, using a low-temperature, noncontact fabrication method, which is also large-area compatible. This development may pave a way to new fabrication methodologies for optical devices requiring light management at the nanoscale. PMID:26933686

  11. Ultra-broadband light trapping using nanotextured decoupled graphene multilayers.

    PubMed

    Anguita, José V; Ahmad, Muhammad; Haq, Sajad; Allam, Jeremy; Silva, S Ravi P

    2016-02-01

    The ability to engineer a thin two-dimensional surface for light trapping across an ultra-broad spectral range is central for an increasing number of applications including energy, optoelectronics, and spectroscopy. Although broadband light trapping has been obtained in tall structures of carbon nanotubes with millimeter-tall dimensions, obtaining such broadband light-trapping behavior from nanometer-scale absorbers remains elusive. We report a method for trapping the optical field coincident with few-layer decoupled graphene using field localization within a disordered distribution of subwavelength-sized nanotexturing metal particles. We show that the combination of the broadband light-coupling effect from the disordered nanotexture combined with the natural thinness and remarkably high and wavelength-independent absorption of graphene results in an ultrathin (15 nm thin) yet ultra-broadband blackbody absorber, featuring 99% absorption spanning from the mid-infrared to the ultraviolet. We demonstrate the utility of our approach to produce the blackbody absorber on delicate opto-microelectromechanical infrared emitters, using a low-temperature, noncontact fabrication method, which is also large-area compatible. This development may pave a way to new fabrication methodologies for optical devices requiring light management at the nanoscale. PMID:26933686

  12. Migration to Broadband and Ubiquitous Environments by Using Fiber-Optic Technologies in Access/Home Areas

    NASA Astrophysics Data System (ADS)

    Oguchi, Kimio

    2016-03-01

    The recent dramatic advances in information and communication technologies have yielded new environments. However, adoption still differs area by area. To realize the future broadband environment that everyone can enjoy everywhere, several technical issues have to be resolved before network penetration becomes ubiquitous. One such key is the use of fiber optics for the home and mobile services. This article overviews initial observations drawn from numerical survey data gathered over the last decade in several countries/regions, and gives some example scenarios for network/service evolution. One result implies that implementing new/future services must consider the gross domestic product impact.

  13. Demarcating Advanced Learning Approaches from Methodological and Technological Perspectives

    ERIC Educational Resources Information Center

    Horvath, Imre; Peck, David; Verlinden, Jouke

    2009-01-01

    In the field of design and engineering education, the fast and expansive evolution of information and communication technologies is steadily converting traditional learning approaches into more advanced ones. Facilitated by Broadband (high bandwidth) personal computers, distance learning has developed into web-hosted electronic learning. The…

  14. Broadband polarization gratings for efficient liquid crystal display, beam steering, spectropolarimetry, and Fresnel zone plate

    NASA Astrophysics Data System (ADS)

    Oh, Chulwoo

    Efficient control of light polarization is essential in any optical systems where polarized light is used or polarization information is of interest. In addition to intensity and wavelength, polarization of light gives a very useful/powerful tool to control light itself and observe many interesting optical phenomena in nature and applications. Most available light sources, however, produce unpolarized or weakly polarized light except some of fancy lasers. Therefore, efficient polarization control/generation is important to improve/advance existing or emerging technologies utilizing polarized light. It is also true that polarization can be used to control another properties of light (i.e., intensity, direction). We have introduced and demonstrated achromatic polarization gratings (PGs) as broadband polarizing beam splitters performing ˜100% theoretical efficiency over a wide spectral range. The novel design of achromatic PGs and their effective fabrication method will be presented. Experimental demonstration will show that practically 100% efficient diffraction is achieved by achromatic PGs embodied as thin liquid crystal (LC) layers patterned by holographic photoalignment techniques. Non-ideal diffraction behaviors of the PGs also have been investigated beyond the paraxial limitations via numerical analysis based on the finite-difference time-domain method. We, first, study the effect of the grating regime for this special type of anisotropic diffraction gratings with the minimum assumptions. Optical properties of the PGs at oblique incidence angles and in a finite pixel are numerically predicted and confirmed by experiments. Design and fabrication of small-period PGs are discussed to show how to achieve high diffraction efficiency and large diffraction angles at the same time. Three key innovative technologies utilizing the unique diffraction properties of the PGs have been introduced and experimentally demonstrated. The first application for light-efficient LC

  15. Broadband ferromagnetic resonance system and methods for ultrathin magnetic films

    NASA Astrophysics Data System (ADS)

    Montoya, Eric; McKinnon, Tommy; Zamani, Atieh; Girt, Erol; Heinrich, Bret

    2014-04-01

    Spintronics requires the development of magnetic thin film structures having a wide range of magnetic properties. Ferromagnetic resonance (FMR) is a well understood experimental technique that has proven to be an invaluable tool to probe the static and dynamic magnetic properties of ultrathin films, multilayer nanostructures, and superlattices. In order to achieve a full characterization of thin film materials, one needs to carry out FMR measurements at a wide range of microwave frequencies. In this paper, we show that one does not have to use a broadband vector network analyzer; similar performance can be achieved by using a broadband microwave signal generator, a coplanar waveguide, and a broadband microwave detector. To obtain a good signal to noise ratio, one needs to employ a modulation technique in order to use lock-in detection; in this paper, we use low frequency external field modulation (105 Hz) and microwave power amplitude pulse modulation (10 kHz). The sensitivity and the performance of this broadband microwave system is demonstrated on two types of samples: molecular beam epitaxy grown single crystal GaAs(001)/Fe/Au and sputter deposited textured Si(111)/Ta/Ru/Co/Ru superlattice structures. The samples were mounted on a coplanar waveguide, allowing one a broadband measurement, ~0.1-50 GHz, of DC field swept FMR signals. The results are compared to traditional field swept, field modulated measurements in microwave cavity resonators. Despite the fact that the FMR signal can be very different from that obtained by standard microwave cavities, we show that the analysis of the FMR signal is fairly simple using an admixture of the in-phase and out-of-phase components of rf susceptibility and that the resulting fitted magnetic parameters are in excellent agreement. Additionally, we demonstrate that microwave power amplitude pulse modulation can be used to greatly speed up data collection times, especially for very weak and broad FMR signals.

  16. Measuring Broadband IR Irradiance in the Direct Solar Beam (Presentation)

    SciTech Connect

    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)

    SciTech Connect

    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. Atmospheric extinction in solar tower plants: the Absorption and Broadband Correction for MOR measurements

    NASA Astrophysics Data System (ADS)

    Hanrieder, N.; Wilbert, S.; Pitz-Paal, R.; Emde, C.; Gasteiger, J.; Mayer, B.; Polo, J.

    2015-05-01

    Losses of reflected Direct Normal Irradiance due to atmospheric extinction in concentrating solar tower plants can vary significantly with site and time. The losses of the direct normal irradiance between the heliostat field and receiver in a solar tower plant are mainly caused by atmospheric scattering and absorption by aerosol and water vapor concentration in the atmospheric boundary layer. Due to a high aerosol particle number, radiation losses can be significantly larger in desert environments compared to the standard atmospheric conditions which are usually considered in raytracing or plant optimization tools. Information about on-site atmospheric extinction is only rarely available. To measure these radiation losses, two different commercially available instruments were tested and more than 19 months of measurements were collected at the Plataforma Solar de Almería and compared. Both instruments are primarily used to determine the meteorological optical range (MOR). The Vaisala FS11 scatterometer is based on a monochromatic near-infrared light source emission and measures the strength of scattering processes in a small air volume mainly caused by aerosol particles. The Optec LPV4 long-path visibility transmissometer determines the monochromatic attenuation between a light-emitting diode (LED) light source at 532 nm and a receiver and therefore also accounts for absorption processes. As the broadband solar attenuation is of interest for solar resource assessment for Concentrating Solar Power (CSP), a correction procedure for these two instruments is developed and tested. This procedure includes a spectral correction of both instruments from monochromatic to broadband attenuation. That means the attenuation is corrected for the actual, time-dependent by the collector reflected solar spectrum. Further, an absorption correction for the Vaisala FS11 scatterometer is implemented. To optimize the Absorption and Broadband Correction (ABC) procedure, additional

  19. DXBC: a long distance wireless broadband communication system for coastal maritime surveillance applications

    NASA Astrophysics Data System (ADS)

    Vastianos, George E.; Argyreas, Nick D.; Xilouris, Chris K.; Thomopoulos, Stelios C. A.

    2015-05-01

    The field of Homeland Security focuses on the air, land, and sea borders surveillance in order to prevent illegal activities while facilitating lawful travel and trade. The achievement of this goal requires collaboration of complex decentralized systems and services, and transfer of huge amount of information between the remote surveillance areas and the command & control centers. It becomes obvious that the effectiveness of the provided security depends highly on the available communication capabilities between the interconnected areas. Although nowadays the broadband communication between remote places is presumed easy because of the extensive infrastructure inside residential areas, it becomes a real challenge when the required information should be acquired from locations where no infrastructure is available such as mountain or sea areas. The Integrated Systems Lab of NCSR Demokritos within the PERSEUS FP7- SEC-2011-261748 project has developed a wireless broadband telecommunication system that combines different communication channels from subGHz to microwave frequencies and provides secure IP connectivity between sea surveillance vessels and the Command and Control Centers (C3). The system was deployed in Fast Patrol Boats of the Hellenic Coast Guard that are used for maritime surveillance in sea boarders and tested successfully in two demonstration exercises for irregular migration and smuggling scenarios in the Aegean Archipelagos. This paper describes in detail the system architecture in terms of hardware and software and the evaluation measurements of the system communication capabilities.

  20. A JET MODEL FOR THE BROADBAND SPECTRUM OF THE SEYFERT 1 GALAXY NGC 4051

    SciTech Connect

    Maitra, Dipankar; Miller, Jon M.; King, Ashley; Markoff, Sera

    2011-07-10

    Recent radio very long baseline interferometry observations of the {approx} parsec-scale nuclear region of the narrow line Seyfert 1 galaxy NGC 4051 hint toward the presence of outflowing plasma. From available literature we have collected high-quality, high-resolution broadband spectral energy distribution (SED) data of the nuclear region of NGC 4051 spanning from radio through X-rays, to test whether the broadband SED can be explained within the framework of a relativistically outflowing jet model. We show that once the contribution from the host galaxy is taken into account, the broadband emission from the active galactic nucleus (AGN) of NGC 4051 can be well described by the jet model. Contributions from dust and ongoing star formation in the nuclear region tend to dominate the IR emission even at the highest resolutions. In the framework of the jet model, the correlated high variability of the extreme-ultraviolet and X-rays compared to other wavelengths suggests that the emission at these wavelengths is optically thin synchrotron originating in the particle acceleration site(s) in the jet very close (few r{sub g}= GM{sub BH}/c{sup 2}) to the central supermassive black hole of mass M{sub BH}. Our conclusions support the hypothesis that narrow line Seyfert 1 galaxies (which NGC 4051 is a member of) harbor a 'jetted' outflow with properties similar to what has already been seen in low-luminosity AGNs and stellar mass black holes in hard X-ray state.

  1. Broad-band near-field ground motion simulations in 3-dimensional scattering media

    NASA Astrophysics Data System (ADS)

    Imperatori, W.; Mai, P. M.

    2013-02-01

    The heterogeneous nature of Earth's crust is manifested in the scattering of propagating seismic waves. In recent years, different techniques have been developed to include such phenomenon in broad-band ground-motion calculations, either considering scattering as a semi-stochastic or purely stochastic process. In this study, we simulate broad-band (0-10 Hz) ground motions with a 3-D finite-difference wave propagation solver using several 3-D media characterized by von Karman correlation functions with different correlation lengths and standard deviation values. Our goal is to investigate scattering characteristics and its influence on the seismic wavefield at short and intermediate distances from the source in terms of ground motion parameters. We also examine scattering phenomena, related to the loss of radiation pattern and the directivity breakdown. We first simulate broad-band ground motions for a point-source characterized by a classic ω2 spectrum model. Fault finiteness is then introduced by means of a Haskell-type source model presenting both subshear and super-shear rupture speed. Results indicate that scattering plays an important role in ground motion even at short distances from the source, where source effects are thought to be dominating. In particular, peak ground motion parameters can be affected even at relatively low frequencies, implying that earthquake ground-motion simulations should include scattering also for peak ground velocity (PGV) calculations. At the same time, we find a gradual loss of the source signature in the 2-5 Hz frequency range, together with a distortion of the Mach cones in case of super-shear rupture. For more complex source models and truly heterogeneous Earth, these effects may occur even at lower frequencies. Our simulations suggests that von Karman correlation functions with correlation length between several hundred metres and few kilometres, Hurst exponent around 0.3 and standard deviation in the 5-10 per cent range

  2. Locating and Modeling Regional Earthquakes with Broadband Waveform Data

    NASA Astrophysics Data System (ADS)

    Tan, Y.; Zhu, L.; Helmberger, D.

    2003-12-01

    Retrieving source parameters of small earthquakes (Mw < 4.5), including mechanism, depth, location and origin time, relies on local and regional seismic data. Although source characterization for such small events achieves a satisfactory stage in some places with a dense seismic network, such as TriNet, Southern California, a worthy revisit to the historical events in these places or an effective, real-time investigation of small events in many other places, where normally only a few local waveforms plus some short-period recordings are available, is still a problem. To address this issue, we introduce a new type of approach that estimates location, depth, origin time and fault parameters based on 3-component waveform matching in terms of separated Pnl, Rayleigh and Love waves. We show that most local waveforms can be well modeled by a regionalized 1-D model plus different timing corrections for Pnl, Rayleigh and Love waves at relatively long periods, i.e., 4-100 sec for Pnl, and 8-100 sec for surface waves, except for few anomalous paths involving greater structural complexity, meanwhile, these timing corrections reveal similar azimuthal patterns for well-located cluster events, despite their different focal mechanisms. Thus, we can calibrate the paths separately for Pnl, Rayleigh and Love waves with the timing corrections from well-determined events widely recorded by a dense modern seismic network or a temporary PASSCAL experiment. In return, we can locate events and extract their fault parameters by waveform matching for available waveform data, which could be as less as from two stations, assuming timing corrections from the calibration. The accuracy of the obtained source parameters is subject to the error carried by the events used for the calibration. The detailed method requires a Green­_s function library constructed from a regionalized 1-D model together with necessary calibration information, and adopts a grid search strategy for both hypercenter and

  3. The National Heart, Lung, and Blood Institute retrovirus epidemiology donor studies (Retrovirus Epidemiology Donor Study and Retrovirus Epidemiology Donor Study-II): twenty years of research to advance blood product safety and availability.

    PubMed

    Kleinman, Steven; King, Melissa R; Busch, Michael P; Murphy, Edward L; Glynn, Simone A

    2012-10-01

    The Retrovirus Epidemiology Donor Study (REDS), conducted from 1989 to 2001, and the REDS-II, conducted from 2004 to 2012, were National Heart, Lung, and Blood Institute-funded, multicenter programs focused on improving blood safety and availability in the United States. The REDS-II also included international study sites in Brazil and China. The 3 major research domains of REDS/REDS-II have been infectious disease risk evaluation, blood donation availability, and blood donor characterization. Both programs have made significant contributions to transfusion medicine research methodology by the use of mathematical modeling, large-scale donor surveys, innovative methods of repository sample storage, and establishing an infrastructure that responded to potential emerging blood safety threats such as xenotropic murine leukemia virus-related virus. Blood safety studies have included protocols evaluating epidemiologic and/or laboratory aspects of human immunodeficiency virus, human T-lymphotropic virus 1/2, hepatitis C virus, hepatitis B virus, West Nile virus, cytomegalovirus, human herpesvirus 8, parvovirus B19, malaria, Creutzfeldt-Jakob disease, influenza, and Trypanosoma cruzi infections. Other analyses have characterized blood donor demographics, motivations to donate, factors influencing donor return, behavioral risk factors, donors' perception of the blood donation screening process, and aspects of donor deferral. In REDS-II, 2 large-scale blood donor protocols examined iron deficiency in donors and the prevalence of leukocyte antibodies. This review describes the major study results from over 150 peer-reviewed articles published by these 2 REDS programs. In 2011, a new 7-year program, the Recipient Epidemiology and Donor Evaluation Study-III, was launched. The Recipient Epidemiology and Donor Evaluation Study-III expands beyond donor-based research to include studies of blood transfusion recipients in the hospital setting and adds a third country, South Africa

  4. 75 FR 3820 - Broadband Initiatives Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-22

    ... Telecommunication Information Administration (NTIA) issued a joint Notice of Funds Availability at 74 FR 33104..., 2009, at 74 FR 58940, RUS has determined to make the following changes: B. Application Changes From the... having to submit them to RUS.\\5\\ \\5\\ See 74 FR at 58941. The majority of commenters agree that...

  5. Incident angle-tuned, broadband, ultrahigh-sensitivity plasmonic antennas prepared from nanoparticles on imprinted mirrors

    NASA Astrophysics Data System (ADS)

    Yu, Chen-Chieh; Tseng, Yi-Chuan; Su, Pao-Yun; Lin, Keng-Te; Shao, Chang-Ching; Chou, Sin-Yi; Yen, Yu-Ting; Chen, Hsuen-Li

    2015-02-01

    morphologies, the NIMAs achieved broadband electromagnetic enhancement from single configurations. The enhancement of the electric field intensity in the NIMAs originated from coupling between the localized surface plasmon resonance of the NPs and the periodic structure-excited surface plasmon resonance (SPR) of the imprinted mirror. Moreover, the coupling wavelengths could be modulated because the SPR wavelength was readily tuned by changing the angle of the incident light. Herein, we demonstrate that such NIMAs are robust substrates for visible and NIR surface-enhanced resonance Raman scattering under multiple laser lines (532, 633, and 785 nm) of excitation. In addition, we have found that NIMAs are ultrasensitive SERS-active substrates that can detect analytes (e.g., rhodamine 6G) at concentrations as low as 10-15 M. Electronic supplementary information (ESI) available: Additional SERS spectra of malachite green and CF790 dye. See DOI: 10.1039/c4nr05902f

  6. Responses of Cell Renewal Systems to Long-term Low-Level Radiation Exposure: A Feasibility Study Applying Advanced Molecular Biology Techniques on Available Histological and Cytological Material of Exposed Animals and Men

    SciTech Connect

    Fliedner Theodor M.; Feinendegen Ludwig E.; Meineke Viktor; Fritz Thomas E.

    2005-02-28

    First results of this feasibility study showed that evaluation of the stored material of the chronically irradiated dogs with modern molecular biological techniques proved to be successful and extremely promising. Therefore an in deep analysis of at least part of the huge amount of remaining material is of outmost interest. The methods applied in this feasibility study were pathological evaluation with different staining methods, protein analysis by means of immunohistochemistry, strand break analysis with the TdT-assay, DNA- and RNA-analysis as well as genomic examination by gene array. Overall more than 50% of the investigated material could be used. In particular the results of an increased stimulation of the immune system within the dogs of the 3mSv group as both compared to the control and higher dose groups gives implications for the in depth study of the cellular events occurring in context with low dose radiation. Based on the findings of this study a further evaluation and statistically analysis of more material can help to identify promising biomarkers for low dose radiation. A systematic evaluation of a correlation of dose rates and strand breaks within the dog tissue might moreover help to explain mechanisms of tolerance to IR. One central problem is that most sequences for dog specific primers are not known yet. The discovery of the dog genome is still under progress. In this study the isolation of RNA within the dog tissue was successful. But up to now there are no gene arrays or gene chips commercially available, tested and adapted for canine tissue. The uncritical use of untested genomic test systems for canine tissue seems to be ineffective at the moment, time consuming and ineffective. Next steps in the investigation of genomic changes after IR within the stored dog tissue should be limited to quantitative RT-PCR of tested primer sequences for the dog. A collaboration with institutions working in the field of the discovery of the dog genome could

  7. Giant and broadband circular asymmetric transmission based on two cascading polarization conversion cavities

    NASA Astrophysics Data System (ADS)

    Ji, Ruonan; Wang, Shao-Wei; Liu, Xingxing; Lu, Wei

    2016-04-01

    In this paper, a three-layered sandwiched metamaterial is proposed to achieve giant and broadband asymmetric transmission of circularly polarized waves at the near-infrared communication band. The metamaterial consists of two layers of identical 45° tilted chiral S-shaped metasurfaces sandwiched with a subwavelength metallic grating. Based on the delicate combination of broadband polarization conversion and a cavity-enhanced effect, the asymmetric parameter can reach a maximum value of 0.87 and over 0.6 in a wide range from 1.2 to 2.0 μm, which has not been found in previous reports. Furthermore, a perfect robustness to misalignments is obtained as the effect originated from function-independent cascading cavities, which effectively reduce the requirement of alignment precision in layer-by-layer photolithography processes. The proposed nanostructure has a great potential to be used as a circular polarization rotator or diode-like device in optical communication systems.In this paper, a three-layered sandwiched metamaterial is proposed to achieve giant and broadband asymmetric transmission of circularly polarized waves at the near-infrared communication band. The metamaterial consists of two layers of identical 45° tilted chiral S-shaped metasurfaces sandwiched with a subwavelength metallic grating. Based on the delicate combination of broadband polarization conversion and a cavity-enhanced effect, the asymmetric parameter can reach a maximum value of 0.87 and over 0.6 in a wide range from 1.2 to 2.0 μm, which has not been found in previous reports. Furthermore, a perfect robustness to misalignments is obtained as the effect originated from function-independent cascading cavities, which effectively reduce the requirement of alignment precision in layer-by-layer photolithography processes. The proposed nanostructure has a great potential to be used as a circular polarization rotator or diode-like device in optical communication systems. Electronic supplementary

  8. Broad-band spectrophotometry of HAT-P-32 b: Search for a scattering signature in the planetary spectrum

    NASA Astrophysics Data System (ADS)

    Mallonn, M.; Bernt, I.; Herrero, E.; Hoyer, S.; Kirk, J.; Wheatley, P. J.; Seeliger, M.; Mackebrandt, F.; von Essen, C.; Strassmeier, K. G.; Granzer, T.; Künstler, A.; Dhillon, V. S.; Marsh, T. R.; Gaitan, J.

    2016-08-01

    Multi-colour broad-band transit observations offer the opportunity to characterise the atmosphere of an extrasolar planet with small- to medium-sized telescopes. One of the most favourable targets is the hot Jupiter HAT-P-32 b. We combined 21 new transit observations of this planet with 36 previously published light curves for a homogeneous analysis of the broad-band transmission spectrum from the Sloan u' band to the Sloan z' band. Our results rule out cloud-free planetary atmosphere models of solar metallicity. Furthermore, a discrepancy at reddest wavelengths to previously published results makes a recent tentative detection of a scattering feature less likely. Instead, the available spectral measurements of HAT-P-32 b favour a completely flat spectrum from the near-UV to the near-IR. A plausible interpretation is a thick cloud cover at high altitudes.

  9. Broadband, optical Internet-based, modular, interactive information system for research deptartment in university environment: part II

    NASA Astrophysics Data System (ADS)

    Koprek, Waldemar; Stepien, Marcin; Wojtas, Marcin; Pozniak, Krzysztof T.; Romaniuk, Ryszard S.

    2005-02-01

    The work describes selected components of a standardized, modular and interactive broadband Internet based, information system for a research and didactic unit at the WUT. There are presented descriptions of the realization of a few issues and achievements which are the results of work continuation on the web service for the Measurement Systems and Optoelectronics Unit (referred later to as the ZSPiO) of the Institute of Electronic Systems in the Department of Electronics and Information Technologies of the Warsaw University of Technology. The service is available through the ISE WUT portal www.ise.pw.edu.pl. The theoretical and design considerations were implemented practically in the existing web service. The further chapters describe all solutions and their implementations. The first part of this work was published in reference 1. The application uses broadband Internet LAN.

  10. Availability growth modeling

    SciTech Connect

    Wendelberger, J.R.

    1998-12-01

    In reliability modeling, the term availability is used to represent the fraction of time that a process is operating successfully. Several different definitions have been proposed for different types of availability. One commonly used measure of availability is cumulative availability, which is defined as the ratio of the amount of time that a system is up and running to the total elapsed time. During the startup phase of a process, cumulative availability may be treated as a growth process. A procedure for modeling cumulative availability as a function of time is proposed. Estimates of other measures of availability are derived from the estimated cumulative availability function. The use of empirical Bayes techniques to improve the resulting estimates is also discussed.

  11. The improved broadband Real-Time Seismic Network in Romania

    NASA Astrophysics Data System (ADS)

    Neagoe, C.; Ionescu, C.

    2009-04-01

    Starting with 2002 the National Institute for Earth Physics (NIEP) has developed its real-time digital seismic network. This network consists of 96 seismic stations of which 48 broad band and short period stations and two seismic arrays are transmitted in real-time. The real time seismic stations are equipped with Quanterra Q330 and K2 digitizers, broadband seismometers (STS2, CMG40T, CMG 3ESP, CMG3T) and strong motions sensors Kinemetrics episensors (+/- 2g). SeedLink and AntelopeTM (installed on MARMOT) program packages are used for real-time (RT) data acquisition and exchange. The communication from digital seismic stations to the National Data Center in Bucharest is assured by 5 providers (GPRS, VPN, satellite communication, radio lease line and internet), which will assure the back-up communications lines. The processing centre runs BRTT's AntelopeTM 4.10 data acquisition and processing software on 2 workstations for real-time processing and post processing. The Antelope Real-Time System is also providing automatic event detection, arrival picking, event location and magnitude calculation. It provides graphical display and reporting within near-real-time after a local or regional event occurred. Also at the data center was implemented a system to collect macroseismic information using the internet on which macro seismic intensity maps are generated. In the near future at the data center will be install Seiscomp 3 data acquisition processing software on a workstation. The software will run in parallel with Antelope software as a back-up. The present network will be expanded in the near future. In the first half of 2009 NIEP will install 8 additional broad band stations in Romanian territory, which also will be transmitted to the data center in real time. The Romanian Seismic Network is permanently exchanging real -time waveform data with IRIS, ORFEUS and different European countries through internet. In Romania, magnitude and location of an earthquake are now

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

    PubMed

    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

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

    NASA Astrophysics Data System (ADS)

    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

  14. Ultra-broadband wavelength conversion sensor using thermochromic liquid crystals

    NASA Astrophysics Data System (ADS)

    Chen, Ichun Anderson; Park, S. W.; Chen, G.; Wang, C.; Bethea, C.; Martini, R.; Woolard, D.

    2013-03-01

    Wavelength conversion (WC) imaging is a methodology that employs temperature sensitive detectors to convert photoinduced termperature into a detectable optical signal. One specific method is to use molecular detectors such as thermochromic liquid crystals (TLC), which exhibits thermochromism to observe the surface temperature of an area by observing the apparent color in the visible spectrum. Utilizing this methodology, an ultra-broadband room temperature imaging system was envisioned and realized using off the shelf thermochromic liquid crystals. The thermochromic properties of the sensor were characterized to show a thermochromic coefficient α = 10%/°K and a noise equivalent power (NEP) of 64 μW. With the TLC camera, images of both pulsed and continuous wave (CW) sources spanning 0.6 μm to 150 μm wavelengths were captured to demonstrate its potential as a portable, low-cost, and ultra-broadband imaging tool.

  15. High-frequency Broadband Modulations of Electroencephalographic Spectra

    PubMed Central

    Onton, Julie; Makeig, Scott

    2009-01-01

    High-frequency cortical potentials in electroencephalographic (EEG) scalp recordings have low amplitudes and may be confounded with scalp muscle activities. EEG data from an eyes-closed emotion imagination task were linearly decomposed using independent component analysis (ICA) into maximally independent component (IC) processes. Joint decomposition of IC log spectrograms into source- and frequency-independent modulator (IM) processes revealed three distinct classes of IMs that separately modulated broadband high-frequency (∼15–200 Hz) power of brain, scalp muscle, and likely ocular motor IC processes. Multi-dimensional scaling revealed significant but spatially complex relationships between mean broadband brain IM effects and the valence of the imagined emotions. Thus, contrary to prevalent assumption, unitary modes of spectral modulation of frequencies encompassing the beta, gamma, and high gamma frequency ranges can be isolated from scalp-recorded EEG data and may be differentially associated with brain sources and cognitive activities. PMID:20076775

  16. Broadband Plasmonic Microlenses based on Patches of Nanoholes

    PubMed Central

    Gao, Hanwei; Hyun, Jerome K.; Lee, Min Hyung; Yang, Jiun-Chan; Lauhon, Lincoln J.; Odom, Teri W.

    2010-01-01

    This paper reports a new type of diffractive microlens based on finite-areas of 2D arrays of circular nanoholes (patches). The plasmonic microlenses can focus single wavelengths of light across the entire visible spectrum as well as broadband white light with little divergence. The focal length is determined primarily by the overall size of the patch and is tolerant to significant changes in patch substructure, including lattice geometry and local order of the circular nanoholes. The optical throughput, however, depends sensitively on the patch substructure and is determined by the wavelengths of surface plasmon resonances. This simple diffractive lens design enables millions of broadband plasmonic microlenses to be fabricated in parallel using soft nanolithographic techniques. PMID:20839781

  17. Broadband terahertz metamaterial absorber based on sectional asymmetric structures.

    PubMed

    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

  18. Broadband pump-probe spectroscopy at 20-MHz modulation frequency.

    PubMed

    Preda, Fabrizio; Kumar, Vikas; Crisafi, Francesco; Figueroa Del Valle, Diana Gisell; Cerullo, Giulio; Polli, Dario

    2016-07-01

    We introduce an innovative high-sensitivity broadband pump-probe spectroscopy system, based on Fourier-transform detection, operating at 20-MHz modulation frequency. A common-mode interferometer employing birefringent wedges creates two phase-locked delayed replicas of the broadband probe pulse, interfering at a single photodetector. A single-channel lock-in amplifier demodulates the interferogram, whose Fourier transform provides the differential transmission spectrum. Our approach combines broad spectral coverage with high sensitivity, due to high-frequency modulation and detection. We demonstrate its performances by measuring two-dimensional differential transmission maps of a carbon nanotubes sample, simultaneously acquiring the signal over the entire 950-1350 nm range with 2.7·10-6  rms noise over 1.5 s integration time. PMID:27367078

  19. Broadband Wavelength Spanning Holographic Polymer Dispersed Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Rai, Kashma; Shriyan, Sameet; Fontecchio, Adam

    2008-03-01

    Broadened interaction wavelength of holographic polymer dispersed liquid crystals (HPDLCs) have extensive applications in beam steering for instrument clusters, hyperspectral imaging, wavelength filtering and construction of lightweight optics. A novel simultaneous time and spatial multiplexing formation configuration is proposed here, to increase narrow wavelength reflecting notch to broad range wavelength spanning device. HPDLC films have electro-optic controllability by applying field. No moving parts, light weight, small footprint compared to prisms and lenses, high color purity make the broadband wavelength HPDLCs desirable for the above applications. Varying the incident laser beam exposure angles using motorized rotating stage, during formation is the key step here for their formation in a single medium. The fabricated broadband wavelength sensitive HPDLCs are characterized for the uniformity of the reflected peak and electro optic response. Their output wavefront is analyzed using wavefront analysis technique.

  20. Chromatic compensation of broadband light diffraction: ABCD-matrix approach.

    PubMed

    Lancis, Jésus; Mínguez-Vega, Gladys; Tajahuerce, Enrique; Climent, Vicent; Andrés, Pedro; Caraquitena, José

    2004-10-01

    Compensation of chromatic dispersion for the optical implementation of mathematical transformations has proved to be an important tool in the design of new optical methods for full-color signal processing. A novel approach for designing dispersion-compensated, broadband optical transformers, both Fourier and Fresnel, based on the collimated Fresnel number is introduced. In a second stage, the above framework is fully exploited to achieve the optical implementation of the fractional Fourier transform (FRT) of any diffracting screen with broadband illumination. Moreover, we demonstrate that the amount of shift variance of the dispersion-compensated FRT can be tuned continuously from the spatial domain, which is totally space variant, to the spectral domain, which is totally space invariant, with the chromatic correction remaining unaltered. PMID:15497415

  1. Broadband Fourier-domain mode-locked lasers

    NASA Astrophysics Data System (ADS)

    Hsu, Kevin; Meemon, Panomsak; Lee, Kye-Sung; Delfyett, Peter J.; Rolland, Jannick P.

    2011-09-01

    Broadband, high-speed wavelength-swept lasers can substantially enhance applications in optical coherence tomography, chemical spectroscopy, and fiber-optic sensing. We report the demonstration of Fourier-domain mode-lock lasers operating at about 90 kHz effective sweep rate over a 158 nm sweep range using a single-band design and over a 284 nm sweep range across the 1.3 μm to 1.5 μm wavelength spectrum using a unique broadband design. A novel dual-detection full-range Fourier-domain optical coherence tomography system is developed which provides 7 μm axial resolution (in air) at about 90 kHz axial scan rate for mirror-image resolved Doppler imaging in a human finger and an African frog tadpole.

  2. Metallic stereostructured layer: An approach for broadband polarization state manipulation

    SciTech Connect

    Xiong, Xiang; Hu, Yuan-Sheng; Jiang, Shang-Chi; Hu, Yu-Hui; Fan, Ren-Hao; Ma, Guo-Bin; Shu, Da-Jun; Peng, Ru-Wen; Wang, Mu

    2014-11-17

    In this letter, we report a full-metallic broadband wave plate assembled by standing metallic L-shaped stereostructures (LSSs). We show that with an array of LSSs, high polarization conversion ratio is achieved within a broad frequency band. Moreover, by rotating the orientation of the array of LSSs, the electric components of the reflection beam in two orthogonal directions and their phase difference can be independently tuned. In this way, all the polarization states on the Poincaré sphere can be realized. As examples, the functionalities of a quarter wave plate and a half wave plate are experimentally demonstrated with both reflection spectra and focal-plane-array imaging. Our designing provides a unique approach in realizing the broadband wave plate to manipulate the polarization state of light.

  3. Broadband optical switch based on liquid crystal dynamic scattering.

    PubMed

    Geis, M W; Bos, P J; Liberman, V; Rothschild, M

    2016-06-27

    This work demonstrates a novel broadband optical switch, based on dynamic-scattering effect in liquid crystals (LCs). Dynamic-scattering-mode technology was developed for display applications over four decades ago, but was displaced in favor of the twisted-nematic LCs. However, with the recent development of more stable LCs, dynamic scattering provides advantages over other technologies for optical switching. We demonstrate broadband polarization-insensitive attenuation of light directly passing thought the cell by 4 to 5 orders of magnitude at 633 nm. The attenuation is accomplished by light scattering to higher angles. Switching times of 150 μs to 10% transmission have been demonstrated. No degradation of devices is found after hundreds of switching cycles. The light-rejection mechanism is due to scattering, induced by disruption of LC director orientation with dopant ion motion with an applied electric field. Angular dependence of scattering is characterized as a function of bias voltage. PMID:27410544

  4. Broadband terahertz metamaterial absorber based on sectional asymmetric structures

    PubMed Central

    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

  5. Planar metamaterial-based beam-scanning broadband microwave antenna

    NASA Astrophysics Data System (ADS)

    Dhouibi, Abdallah; Burokur, Shah Nawaz; de Lustrac, André

    2014-05-01

    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.

  6. Broadband electrostatic acoustic transducer for ultrasonic measurements in liquids

    NASA Technical Reports Server (NTRS)

    Cantrell, J. H., Jr.; 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 microns 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.

  7. Broadband and chiral binary dielectric meta-holograms

    PubMed Central

    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

  8. Broadband and chiral binary dielectric meta-holograms.

    PubMed

    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

  9. Broadband solar absorption enhancement via periodic nanostructuring of electrodes

    PubMed Central

    Adachi, Michael M.; Labelle, André J.; Thon, Susanna M.; Lan, Xinzheng; Hoogland, Sjoerd; Sargent, Edward H.

    2013-01-01

    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 1100 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. PMID:24121519

  10. Planar metamaterial-based beam-scanning broadband microwave antenna

    SciTech Connect

    Dhouibi, Abdallah; Burokur, Shah Nawaz Lustrac, André de

    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.

  11. All electrical propagating spin wave spectroscopy with broadband wavevector capability

    NASA Astrophysics Data System (ADS)

    Ciubotaru, F.; Devolder, T.; Manfrini, M.; Adelmann, C.; Radu, I. P.

    2016-07-01

    We developed an all electrical experiment to perform the broadband phase-resolved spectroscopy of propagating spin waves in micrometer sized thin magnetic stripes. The magnetostatic surface spin waves are excited and detected by scaled down to 125 nm wide inductive antennas, which award ultra broadband wavevector capability. The wavevector selection can be done by applying an excitation frequency above the ferromagnetic resonance. Wavevector demultiplexing is done at the spin wave detector thanks to the rotation of the spin wave phase upon propagation. A simple model accounts for the main features of the apparatus transfer functions. Our approach opens an avenue for the all electrical study of wavevector-dependent spin wave properties including dispersion spectra or non-reciprocal propagation.

  12. Dispersion multiplexing with broadband filtering for miniature spectrometers.

    PubMed

    Cull, E C; Gehm, M E; Brady, D J; Hsieh, C R; Momtahan, O; Adibi, A

    2007-01-20

    We replace the traditional grating used in a dispersive spectrometer with a multiplex holographic grating to increase the spectral range sensed by the instrument. The multiplexed grating allows us to measure three different, overlapping spectral bands on a color digital focal plane. The detector's broadband color filters, along with a computational inversion algorithm, let us disambiguate measurements made from the three bands. The overlapping spectral bands allow us to measure a greater spectral bandwidth than a traditional spectrometer with the same sized detector. Additionally, our spectrometer uses a static coded aperture mask in the place of a slit. The aperture mask allows increased light throughput, offsetting the photon loss at the broadband filters. We present our proof-of-concept dispersion multiplexing spectrometer design with experimental measurements to verify its operation. PMID:17228382

  13. Diffraction using laser-driven broadband electron wave packets

    NASA Astrophysics Data System (ADS)

    Xu, Junliang; Blaga, Cosmin I.; Zhang, Kaikai; Lai, Yu Hang; Lin, C. D.; Miller, Terry A.; Agostini, Pierre; Dimauro, Louis F.

    2014-08-01

    Directly monitoring atomic motion during a molecular transformation with atomic-scale spatio-temporal resolution is a frontier of ultrafast optical science and physical chemistry. Here we provide the foundation for a new imaging method, fixed-angle broadband laser-induced electron scattering, based on structural retrieval by direct one-dimensional Fourier transform of a photoelectron energy distribution observed along the polarization direction of an intense ultrafast light pulse. The approach exploits the scattering of a broadband wave packet created by strong-field tunnel ionization to self-interrogate the molecular structure with picometre spatial resolution and bond specificity. With its inherent femtosecond resolution, combining our technique with molecular alignment can, in principle, provide the basis for time-resolved tomography for multi-dimensional transient structural determination.

  14. Diffraction using laser-driven broadband electron wave packets

    NASA Astrophysics Data System (ADS)

    Xu, Junliang; Blaga, Cosmin I.; Zhang, Kaikai; Lai, Yu Hang; Lin, C. D.; Miller, Terry A.; Agostini, Pierre; Dimauro, Louis F.

    2015-05-01

    Directly monitoring atomic motion during a molecular transformation with atomic-scale spatio-temporal resolution is a frontier of ultrafast optical science and physical chemistry. Here we provide the foundation for a new imaging method, fixed-angle broadband laser-induced electron scattering, based on structural retrieval by direct one-dimensional Fourier transform of a photoelectron energy distribution observed along the polarization direction of an intense ultrafast light pulse. The approach exploits the scattering of a broadband wave packet created by strong-field tunnel ionization to self-interrogate the molecular structure with picometer spatial resolution and bond specificity. With its inherent femtosecond resolution, combining our technique with molecular alignment can, in principle, provide the basis for time-resolved tomography for multi-dimensional transient structural determination.

  15. Wave propagation in reconfigurable broadband gain metamaterials at microwave frequencies

    NASA Astrophysics Data System (ADS)

    Fan, Yifeng; Nagarkoti, Deepak S.; Rajab, Khalid Z.; Hao, Yang; Zhang, Hao Chi; Cui, Tie Jun

    2016-05-01

    The wave dispersion characteristics for loop array-based metamaterials were analyzed, based on the general transmission line model of a one-dimensional host medium interacting with a chain of coupled loops. By relating the wave propagation constant and the effective parameters of the coupled host medium, we showed that an active medium embedded with non-Foster loaded loop array can be designed to exhibit broadband negative material parameters with positive gain. Accounting for all interactions, the stability of the active medium was investigated, further yielding necessary design specifications for the non-Foster loads. Subsequently, an experimental demonstration was provided to verify the theoretical analysis, showing that stable reconfigurable broadband gain metamaterials at microwave frequencies can be obtained with proper negative impedance converter design.

  16. Tapered fluorotellurite microstructured fibers for broadband supercontinuum generation.

    PubMed

    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

  17. Photoexcited broadband blueshift tunable perfect terahertz metamaterial absorber

    NASA Astrophysics Data System (ADS)

    Xu, Zong-Cheng; Gao, Run-Mei; Ding, Chun-Feng; Wu, Liang; Zhang, Ya-Ting; Yao, Jian-Quan

    2015-04-01

    We present an demonstration of optically tunable metamaterial absorber at terahertz frequencies. The metamaterials are based on two split ring resonators (SSRs) that can be tuned by integrating photoconductive silicon into the metamaterial unit cell. Filing the gap between the resonator arm with a semiconductor (silicon), leads to easy modification of its optical response through a pump beam which changes conductivity of Si. The conductivity of silicon is a function of incident pump power. Therefore, the conductivity of silicon is tuned effectively by applying an external pump power. We demonstrate that a blueshift of the resonance frequency under illumination can be accomplished and a broadband switch of absorption frequencies varying from 0.68 to 1.41 THz, with a tuning range of 51.8%. The realization of broadband blueshift tunable metamaterial absorber offers opportunities for achieving switchable metamaterial absorber and could be implemented in terahertz devices to achieve additional functionalities.

  18. Optical mesoscopy without the scatter: broadband multispectral optoacoustic mesoscopy

    PubMed Central

    Chekkoury, Andrei; Gateau, Jérôme; Driessen, Wouter; Symvoulidis, Panagiotis; Bézière, Nicolas; Feuchtinger, Annette; Walch, Axel; Ntziachristos, Vasilis

    2015-01-01

    Optical mesoscopy extends the capabilities of biological visualization beyond the limited penetration depth achieved by microscopy. However, imaging of opaque organisms or tissues larger than a few hundred micrometers requires invasive tissue sectioning or chemical treatment of the specimen for clearing photon scattering, an invasive process that is regardless limited with depth. We developed previously unreported broadband optoacoustic mesoscopy as a tomographic modality to enable imaging of optical contrast through several millimeters of tissue, without the need for chemical treatment of tissues. We show that the unique combination of three-dimensional projections over a broad 500 kHz–40 MHz frequency range combined with multi-wavelength illumination is necessary to render broadband multispectral optoacoustic mesoscopy (2B-MSOM) superior to previous optical or optoacoustic mesoscopy implementations. PMID:26417486

  19. Effect of blunt trailing edge on rotor broadband noise

    NASA Technical Reports Server (NTRS)

    Chou, S.-T.; George, A. R.

    1986-01-01

    The production of high-frequency broadband noise by turbulent vortex shedding from rotor blades with blunt trailing edges is investigated analytically. The derivation of the governing equations, analogous to that of Kim and George (1982) for boundary-layer/trailing-edge noise, is explained, and numerical results are compared with the experimental data of Hubbard et al. (1981) and Lowson et al. (1972) in graphs. It is shown that vortex-shedding noise is a significant component of blunt-trailing-edge rotor broadband noise and that the analytical method employed gives reasonable predictions. The need for a better empirical expression for the normalized spectrum and for more measurements of surface pressure fluctuations near blunt trailing edges is indicated.

  20. Spectroscopic low coherence interferometry using a supercontinuum source and an ultra broadband spectrometer

    NASA Astrophysics Data System (ADS)

    Fleischhauer, F.; Caujolle, S.; Feutcher, T.; Rajendram, R.; Leick, L.; Podoleanu, A.

    2016-03-01

    Spectroscopic optical coherence tomography (SOCT) combines the imaging capability of optical coherence tomography with spectroscopic absorption information. SOCT requires a large bandwidth combined with a broadband spectrometer, due to the processing of the measured data, which includes dividing the spectrum in spectral bands. Both, spectral and axial resolution of SOCT depend on the spectral width of each window. A supercontinuum source with its broad spectrum allows a sufficient number of windows combined with a reasonable axial resolution, which depends on the application. Here a SOCT system is used in the visible spectral range from 480 to 730 nm by combining a supercontinuum light source, a Michelson interferometer and a commercial available broadband spectrometer. This wavelength range is chosen because it covers a range of useful absorbers, including that of human proteins. The system is tested with a laser dye rhodamine B for calibration and verification. Rhodamine B has an absorption peak at around 542 nm, which resembles the absorption spectrum of several proteins in the globin group. The results show that the absorption spectrum of rhodamine B can be reconstructed with sufficient accuracy and demonstrate that varying spectroscopic information can be retrieved from different depths.

  1. A high transmission broadband gradient index lens using elastic shell acoustic metamaterial elements.

    PubMed

    Titovich, Alexey S; Norris, Andrew N; Haberman, Michael R

    2016-06-01

    The use of cylindrical elastic shells as elements in acoustic metamaterial devices is demonstrated through simulations and underwater measurements of a cylindrical-to-plane wave lens. Transformation acoustics of a circular region to a square dictate that the effective density in the lens remain constant and equal to that of water. Piecewise approximation to the desired effective compressibility is achieved using a square array with elements based on the elastic shell metamaterial concept developed by Titovich and Norris [J. Acoust. Soc. Am. 136(4), 1601-1609 (2014)]. The sizes of the elements are chosen based on availability of shells, minimizing fabrication difficulties. The tested device is neutrally buoyant comprising 48 elements of nine different types of commercial shells made from aluminum, brass, copper, and polymers. Simulations indicate a broadband range in which the device acts as a cylindrical to plane wave lens. The experimental findings confirm the broadband quadropolar response from approximately 20 to 40 kHz, with positive gain of the radiation pattern in the four plane wave directions. PMID:27369162

  2. Broadband adiabatic inversion pulses for cross polarization in wideline solid-state NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Harris, Kristopher J.; Lupulescu, Adonis; Lucier, Bryan E. G.; Frydman, Lucio; Schurko, Robert W.

    2012-11-01

    Efficient acquisition of ultra-wideline solid-state NMR powder patterns is a continuing challenge. In particular, when the breadth of the powder pattern is much larger than the cross-polarization (CP) excitation bandwidth, transfer efficiencies suffer and experimental times are greatly increased. Presented herein is a CP pulse sequence with an excitation bandwidth that is up to ten times greater than that available from a conventional spin-locked CP pulse sequence. The pulse sequence, broadband adiabatic inversion CP (BRAIN-CP), makes use of the broad, uniformly large frequency profiles of chirped inversion pulses, to provide these same characteristics to the polarization transfer process. A detailed theoretical analysis is given, providing insight into the polarization transfer process involved in BRAIN-CP. Experiments on spin-1/2 nuclei including 119Sn, 199Hg and 195Pt nuclei are presented, and the large bandwidth improvements possible with BRAIN-CP are demonstrated. Furthermore, it is shown that BRAIN-CP can be combined with broadband frequency-swept versions of the Carr-Purcell-Meiboom-Gill experiment (for instance with WURST-CPMG, or WCPMG for brevity); the combined BRAIN-CP/WCPMG experiment then provides multiplicative signal enhancements of both CP and multiple-echo acquisition over a broad frequency region.

  3. Disk Structure of Cataclysmic Variables in the light of Broadband Noise Characteristics

    NASA Astrophysics Data System (ADS)

    Balman, Solen

    2016-07-01

    Flicker noise and its variations in accreting systems have been a diagnostic tool in understanding the structure in accretion disks. I study the nature of time variability of brightness of non-magnetic cataclysmic variables. Dwarf novae demonstrate band limited noise in the UV and X-ray energy bands, which can be adequately explained in the framework of the model of propagating fluctuations. The detected frequency breaks in the range (1-6) mHz indicates an optically thick disk truncation in the inner disk of some dwarf novae systems. Analysis of other available data (SS Cyg, SU UMa, WZ Sge, Z Cha) indicate that during the outburst the inner disk radius moves towards the white dwarf and receeds as the outburst declines while changes in the X-ray energy spectrum is also observed. Cross-correlations between the simultaneous Optical, UV and X-ray light curves show time lags in the X-rays consistent with truncated inner optically thick disk. I compare magnetic and nonmagnetic CVs in terms of their broadband noise characteristics and summarize findings regarding broadband noise structure and time lags in other types of nonmagnetic CVs which in general show compliance with the model of propagating fluctuations. In addition, I discuss comparisons with X-ray binaries.

  4. Broadband unidirectional acoustic cloak based on phase gradient metasurfaces with two flat acoustic lenses

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Peng; Wan, Le-Le; Chen, Tian-Ning; Song, Ai-Ling; Wang, Fang

    2016-07-01

    Narrow bandwidth and bulky configuration are the main obstacles for the realization and application of invisible cloaks. In this paper, we present an effective method to achieve broadband and thin acoustic cloak by using an acoustic metasurface (AMS). In order to realize this cloak, we use slitted unit cells to design the AMS due to the advantage of less energy loss, broad operation bandwidth, and subwavelength thickness. According to the hyperboloidal phase profile along the AMS, the incident plane waves can be focused at a designed focal spot by the flat lens. Furthermore, broadband acoustic cloak is obtained by combining two identical flat lenses. The incident plane waves are focused at the center point in between of the two lenses by passing through one lens, and then recovered by passing through the other one. However, they cannot reach the cloaked regions in between of the two lenses. The simulation results can verify the non-detectability effect of the acoustic cloak. Our study results provide an available and simple approach to experimentally achieve the acoustic cloak, which can be used in acoustic non-detectability for large objects.

  5. Broadband infrared meanderline reflective quarter-wave plate.

    PubMed

    Wadsworth, Samuel L; Boreman, Glenn D

    2011-05-23

    We present a novel reflective quarter-wave plate comprised of subwavelength meanderline elements. The device is operational over the long-wave infrared (LWIR) spectrum, with significant spectral and angular bandwidths. Power reflection is approximately 70% over the majority of the LWIR. Efficient conversion from a 45° linear polarization state into circular polarization is demonstrated from finite-element electromagnetic simulations and from broadband polarimetric measurements. PMID:21643314

  6. Broadband Shock Noise Reduction in Turbulent Jets by Water Injection

    NASA Technical Reports Server (NTRS)

    Kandula, Max

    2008-01-01

    The concept of effective jet properties introduced by the author (AIAA-2007-3 645) has been extended to the estimation of broadband shock noise reduction by water injection in supersonic jets. Comparison of the predictions with the test data for cold underexpanded supersonic nozzles shows a satisfactory agreement. The results also reveal the range of water mass flow rates over which saturation of mixing noise reduction and existence of parasitic noise are manifest.

  7. Freely tunable broadband polarization rotator for terahertz waves.

    PubMed

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

    2015-02-18

    A freely tunable polarization rotator for broadband terahertz waves is demonstrated using a three-rotating-layer metallic grating structure, which can conveniently rotate the polarization of a linearly polarized terahertz wave to any desired direction with nearly perfect conversion efficiency. This low-cost, high-efficiency, and freely tunable device has potential applications as material analysis, wireless communication, and THz imaging. PMID:25545177

  8. Broadband study of X-Per using Suzaku observations

    NASA Astrophysics Data System (ADS)

    Maitra, Chandreyee; Paul, Biswajit; Pragati Pradhan, MISS.; Raichur, Harsha

    2016-07-01

    We present detailed broadband timing and spectral analysis of the persistent, low luminosity and slowly spinning pulsar 'X-per' using a Suzaku observation of the source. We have found for the first time, evidence for different intensity states with signatures of changes in the accretion geometry of the source. In addition, we confirm the presence of the cyclotron resonance at 30 keV which varies with the intensity states providing very crucial inputs on the accretion geometry.

  9. A broadband polarization-insensitive cloak based on mode conversion

    NASA Astrophysics Data System (ADS)

    Gu, Chendong; Xu, Yadong; Li, Sucheng; Lu, Weixin; Li, Jensen; Chen, Huanyang; Hou, Bo

    2015-07-01

    In this work, we demonstrate an one-dimensional cloak consisting of parallel-plated waveguide with two slabs of gradient index metamaterials attached to its metallic walls. In it objects are hidden without limitation of polarizations, and good performance is observed for a broadband of frequencies. The experiments at microwave frequencies are carried out, supporting the theoretical results very well. The essential principle behind the proposed cloaking device is based on mode conversion, which provides a new strategy to manipulate wave propagation.

  10. Architecture For Delivery Of Broadband Services To The Residence

    NASA Astrophysics Data System (ADS)

    Coathup, Larry; Goddard, G. W.; McEachern, James; Bears, James

    1990-01-01

    This paper presents a technology and architecture perspective of the cost of evolving today's copper access network, optimized for POTS, to a fiber access network providing both narrowband and broadband services. Architectures are assessed using application studies based on cost models for actual routes in North America. This study identifies three architectures as serious candidates (i.e., close to copper in cost) for providing POTS service in 1992: the double star, the active pedestal and the star-bus.

  11. Broadband Black-Phosphorus Photodetectors with High Responsivity.

    PubMed

    Huang, Mingqiang; Wang, Mingliang; Chen, Cheng; Ma, Zongwei; Li, Xuefei; Han, Junbo; Wu, Yanqing

    2016-05-01

    An array of black-phosphorus photodetectors with channel lengths down to 100 nm is fabricated, and temperature-dependent photodetection measurements from 300 K down to 20 K are carried out. The devices show high photoresponse in a broadband spectral range with a record-high photoresponsivity of 4.3 × 10(6) A W(-1) at 300 K for the 100 nm device. PMID:26969832

  12. Broadband picosecond radiation source based on noncollinear optical parametric amplifier

    SciTech Connect

    Arakcheev, V G; Morozov, V B; Vereshchagin, A K; Vereshchagin, K A; Tunkin, V G; Yakovlev, D V

    2014-04-28

    Amplification of broadband radiation of modeless dye laser by a noncollinear optical parametric amplifier based on a KTP crystal has been implemented upon pumping by 63-ps second-harmonic pulses of a Nd : YAG laser. Pulses with a bandwidth of 21 nm, a duration of 26 ps and an energy of 1.2 mJ have been obtained at the centre wavelength of 685 nm. (nonlinear optical phenomena)

  13. Nonlinear broadband photoluminescence of graphene induced by femtosecond laser irradiation

    SciTech Connect

    Liu, Wei-Tao; Wu, S.W.; Schuck, P.J.; Salmeron, Miquel; Shen, Y.R.; Wang, F.

    2010-07-01

    Upon femtosecond laser irradiation, a bright, broadband photoluminescence is observed from graphene at frequencies well above the excitation frequency. Analyses show that it arises from radiative recombination of a broad distribution of nonequilibrium electrons and holes, generated by rapid scattering between photoexcited carriers within tens of femtoseconds after the optical excitation. Its highly unusual characteristics come from the unique electronic and structural properties of graphene.

  14. Broadband Sources in the 1-3 THz Range

    NASA Technical Reports Server (NTRS)

    Mehdi, Imran; Ward, John; Maestrini, Alain; Chattopadhyay, Goutam; Schlecht, Erich; Thomas, Bertrand; Lin, Robert; Lee, Choonsup; Gill, John

    2009-01-01

    Broadband electronically tunable sources in the terahertz range are a critical technology for enabling space-borne as well as ground-based applications. By power-combining MMIC amplifier and frequency tripler chips, we have recently demonstrated >1 mW of output power at 900 GHz. This source provides a stepping stone to enable sources in the 2-3 THz range than can sufficiently pump multi-pixel imaging arrays.

  15. Surface states controlled broadband enhancement of two-photon absorption

    SciTech Connect

    Zhou, Zhiqiang; Lu, Changgui; Xu, Shuhong; Jiang, Yuan; Yun, Binfeng; Wang, Chunlei; Cui, Yiping

    2013-12-02

    We demonstrate the controllable broadband enhancement of two-photon absorption in a wide spectral range from 710 nm to 960 nm by controlling the surface states of aqueous Co{sup 2+} doped CdTe quantum dots, which is consistent with the measurement results of surface potential and fluorescence decay. The enhancement can be tuned in the range between 1 and 1.7 by changing the dopant concentrations that determine the surface states.

  16. Broadband Photovoltaic Detectors Based on an Atomically Thin Heterostructure.

    PubMed

    Long, Mingsheng; Liu, Erfu; Wang, Peng; Gao, Anyuan; Xia, Hui; Luo, Wei; Wang, Baigeng; Zeng, Junwen; Fu, Yajun; Xu, Kang; Zhou, Wei; Lv, Yangyang; Yao, Shuhua; Lu, Minghui; Chen, Yanfeng; Ni, Zhenhua; You, Yumeng; Zhang, Xueao; Qin, Shiqiao; Shi, Yi; Hu, Weida; Xing, Dingyu; Miao, Feng

    2016-04-13

    van der Waals junctions of two-dimensional materials with an atomically sharp interface open up unprecedented opportunities to design and study functional heterostructures. Semiconducting transition metal dichalcogenides have shown tremendous potential for future applications due to their unique electronic properties and strong light-matter interaction. However, many important optoelectronic applications, such as broadband photodetection, are severely hindered by their limited spectral range and reduced light absorption. Here, we present a p-g-n heterostructure formed by sandwiching graphene with a gapless band structure and wide absorption spectrum in an atomically thin p-n junction to overcome these major limitations. We have successfully demonstrated a MoS2-graphene-WSe2 heterostructure for broadband photodetection in the visible to short-wavelength infrared range at room temperature that exhibits competitive device performance, including a specific detectivity of up to 10(11) Jones in the near-infrared region. Our results pave the way toward the implementation of atomically thin heterostructures for broadband and sensitive optoelectronic applications. PMID:26886761

  17. Broadband circular polarizers constructed using helix-like chiral metamaterials.

    PubMed

    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. PMID:27352818

  18. Sound localization of aerial broadband noise in pinnipeds

    NASA Astrophysics Data System (ADS)

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

    2003-04-01

    Pinnipeds (seals, sea lions, and walruses) emit broadband calls on land as part of their communication system in order to coordinate their reproductive activities. How well do they localize these types of signals? In this study, the aerial sound localization acuities of a harbor seal (Phoca vitulina), a California sea lion (Zalophus californianus), and a northern elephant seal (Mirounga angustirostris) were measured in the horizontal plane with a broadband white noise stimulus. 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 relative to a subject's midline that corresponded to 75% correct discrimination. MAAs were 3.6, 4.2, and 4.7 deg for the harbor seal, California sea lion, and northern elephant seal, respectively. These results demonstrate that these pinniped species had sound localization abilities comparable to the domestic cat and rhesus macaques. The acuity differences between our subjects were small, were not predicted by head size, and therefore likely reflect the relatively acute abilities of other pinniped species to localize aerial broadband signals.

  19. Targeted Broadband UVB Phototherapy forthe Treatment of Localized Vitiligo

    PubMed Central

    Kim, Jeong Eun

    2008-01-01

    Background Several new treatments appear to have higher success rates than previous therapies for the treatment of vitiligo, and targeted phototherapy is an alternative that may prove to be time-efficient and an effective therapeutic option for the management of this condition. Objective The aim of this study was to evaluate the efficacy of targeted broadband UVB phototherapy for the treatment of localized vitiligo. Methods Fifty-three vitiliginous patches on thirty-five patients (16 males, 19 females) were treated using a targeted broadband UVB phototherapy device. Treatment was started at 70% of the minimal erythema dose, and then gradually increased. Lesions were treated twice a week for a maximum of 60 treatment sessions. Results Subjects tolerated treatment well. Forty-one of the fifty-three patches (77.4%) achieved repigmentation on ≤75% of the treated areas. Best results were obtained on the face and neck; 20 of the 24 patches (83.3%) concerned achieved ≤75% repigmentation. The least response was on the hands and feet; 3 of 6 patches (50%) showed ≤75% repigmentation. The results were better for focal type than segmental type vitiligo. Conclusion Targeted broadband UVB phototherapy appears to be highly effective at restoring pigmentation in patients with localized vitiligo. PMID:27303172

  20. Broadband circulator based on spoof surface plasmon polaritons

    NASA Astrophysics Data System (ADS)

    Qiu, Tianshuo; Wang, Jiafu; Li, Yongfeng; Wang, Jun; Qu, Shaobo

    2016-09-01

    In this paper, we proposed a method to design broadband circulators with a compact size. We show that spoof surface plasmon polaritons (SSPPs), which are mediated by metallic blade structures, can be used for the design. The SSPPs wave on metallic blade structures and the transverse electromagnetic (TEM) wave on strip lines are combined to realize wideband circulation performance. A broadband characteristic, which is different from a traditional one, with a compact size can be achieved by combining the SSPPs wave and the TEM wave, which propagates simultaneously in the circulator. The simulation results indicate that from 4.5 GHz to 14 GHz, the return loss and isolation degree basically reaches up to 12 dB and 15 dB, respectively. The mechanism of the broadband transmission characteristic is analyzed using field distributions obtained in simulation. Moreover, the insertion loss is less than 1 dB. This method is helpful to reduce the size of the device and the bulk of ferrite.