WorldWideScience

Sample records for broadband

  1. Adoption of Broadband Services

    DEFF Research Database (Denmark)

    Falch, Morten

    2008-01-01

    successful markets for broadband. This is done through analysis of national policies in three European countries-Denmark, Sweden, and Germany-and the U.S., Japan, and South Korea. We concluded that successful implementation of broadband depends on the kind of policy measures to be taken at the national level....... Many countries have provided active support for stimulating diffusion of broadband and national variants of this type of policies in different countries are important for an explanation of national differences in adoption of broadband....

  2. Passive broadband acoustic thermometry

    Science.gov (United States)

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

    2016-04-01

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

  3. Broadband terahertz spectroscopy

    Institute of Scientific and Technical Information of China (English)

    Wenhui Fan

    2011-01-01

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

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

    Data.gov (United States)

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

  5. Broadband pendulum energy harvester

    Science.gov (United States)

    Liang, Changwei; Wu, You; Zuo, Lei

    2016-09-01

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

  6. Broadband terahertz fiber directional coupler

    DEFF Research Database (Denmark)

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

    2010-01-01

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

  7. Metasurface Broadband Solar Absorber

    CERN Document Server

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

    2015-01-01

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

  8. Broadband Advanced Spectral System Project

    Data.gov (United States)

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

  9. Broadband transmission EPR spectroscopy.

    Directory of Open Access Journals (Sweden)

    Wilfred R Hagen

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

  10. Broadband Rotational Spectroscopy

    Science.gov (United States)

    Pate, Brooks

    2014-06-01

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

  11. Driving demand for broadband networks and services

    CERN Document Server

    Katz, Raul L

    2014-01-01

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

  12. Observations involving broadband impedance modelling

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-08-01

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

  13. Observations involving broadband impedance modelling

    Energy Technology Data Exchange (ETDEWEB)

    Berg, J.S.

    1995-08-01

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

  14. Achieving universal access to broadband

    DEFF Research Database (Denmark)

    Falch, Morten; Henten, Anders

    2009-01-01

    The paper discusses appropriate policy measures for achieving universal access to broadband services in Europe. Access can be delivered by means of many different technology solutions described in the paper. This means a greater degree of competition and affects the kind of policy measures...

  15. Integrated Broadband Quantum Cascade Laser

    Science.gov (United States)

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

    2016-01-01

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

  16. Broadband source of polarization entangled photons.

    Science.gov (United States)

    Fraine, A; Minaeva, O; Simon, D S; Egorov, R; Sergienko, A V

    2012-06-01

    A broadband source of polarization entangled photons based on type-II spontaneous parametric down conversion from a chirped PPKTP crystal is presented. With numerical simulation and experimental evaluation, we report a source of broadband polarization entangled states with a bandwidth of approximately 125 nm for use in quantum interferometry. The technique has the potential to become a basis for the development of flexible broadband sources with designed spectral properties.

  17. Charles Ferguson and the "Broadband Problem"

    OpenAIRE

    2004-01-01

    Charles Ferguson has published a book that advocates a major increase in government intervention in the U.S. market for high-speed, "broadband" Internet services. His proposals are based on a faulty understanding of the effects of current telecommunications regulation and unsubstantiated claims that current participants in the broadband marketplace are exercising monopoly power. His policy recommendations would not only fail to accelerate the pace of broadband diffusion in the United States, ...

  18. Principles of broadband switching and networking

    CERN Document Server

    Liew, Soung C

    2010-01-01

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

  19. Achieving Universal Access to Broadband

    Directory of Open Access Journals (Sweden)

    Morten FALCH

    2009-01-01

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

  20. Understanding broadband over power line

    CERN Document Server

    Held, Gilbert

    2006-01-01

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

  1. Broadband Wireline Provider Service Summary; BBRI_wirelineSum12

    Data.gov (United States)

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

  2. 75 FR 10464 - Broadband Technology Opportunities Program

    Science.gov (United States)

    2010-03-08

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

  3. Broadband Helps Bridge the Achievement Gap

    Science.gov (United States)

    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…

  4. The GEOSCOPE broadband seismic observatory

    Science.gov (United States)

    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

  5. Broadband cloaking for flexural waves

    CERN Document Server

    Zareei, Ahmad

    2016-01-01

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

  6. Interpreting Flux from Broadband Photometry

    CERN Document Server

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

    2016-01-01

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

  7. Broadband fast semiconductor saturable absorber.

    Science.gov (United States)

    Jacobovitz-Veselka, G R; Kellerm, U; Asom, T

    1992-12-15

    Kerr lens mode-locked (KLM) solid-state lasers are typically not self-starting. We address this problem by introducing a broadband semiconductor saturable absorber that could be used as a tunable, all-solid-state, passive starting mechanism. We extend the wavelength tunability of a semiconductor saturable absorber to more than 100 nm using a band-gap-engineered low-temperature molecular-beam-epitaxy (MBE)-grown bulk AlGaAs semiconductor saturable absorber in which the absorption edge of the saturable absorber has been artificially broadened by continuously reducing the Al concentration during the MBE growth. We demonstrate its tunability and its feasibility as a starting mechanism for KLM with a picosecond resonant passive mode-locked Ti:sapphire laser. The extension to femtosecond KLM lasers has been discussed previously.

  8. Tuchola County Broadband Network (TCBN)

    DEFF Research Database (Denmark)

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

    2012-01-01

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

  9. Broadband synthetic aperture geoacoustic inversion.

    Science.gov (United States)

    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.

  10. AIRTV: Broadband Direct to Aircraft

    Science.gov (United States)

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

    2002-01-01

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

  11. SCEC Broadband Platform Strong Ground Motion Simulations

    Science.gov (United States)

    Kumar, S.; Callaghan, S.; Maechling, P. J.; Olsen, K. B.; Archuleta, R. J.; Somerville, P. G.; Graves, R. W.; Jordan, T. H.; Broadband Platform Working Group

    2011-12-01

    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 goal of the SCEC Broadband Simulation Platform is to generate broadband (0-10 Hz) ground motions for earthquakes using deterministic low-frequency and stochastic high-frequency simulations. SCEC developers have integrated complex scientific modules for rupture generation, low-frequency deterministic seismogram synthesis, high-frequency stochastic seismogram synthesis, and non-linear site effects calculation into a system that supports easy on-demand computation of broadband seismograms. The SCEC Broadband platform has two primary modes of operation, validation mode, and scenario mode. In validation mode, the earthquake modeling software calculates broadband seismograms for one of three earthquakes, Northridge, Loma Prieta, or Landers at sites with observed strong motion data. Then, the platform calculates goodness of fit measurements that quantify how well the model-based broadband seismograms match the observed seismograms for each event. In scenario mode, the user can specify a scenario earthquake and a list of sites and calculate ground motions at each site for the scenario event. In February 2011, SCEC released Broadband Platform 11.2 as an open-source scientific software distribution. Since that time, we have continued development of the platform by adding a new site response module and new goodness of fit measures by Mayhew and Olsen. Along with a source code distribution of the Broadband Platform, we now offer a virtual software image distribution of the platform to support its use on a variety of computing hardware and operating systems.

  12. Designing broadband plasmonic nanoantennas for ultrasensing

    Science.gov (United States)

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

    2011-03-01

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

  13. 47 CFR 90.1405 - Shared wireless broadband network.

    Science.gov (United States)

    2010-10-01

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

  14. Analysis of the Proposed Ghana Broadband Strategy

    DEFF Research Database (Denmark)

    Williams, Idongesit; Botwe, Yvonne

    This project studied the Ghana Broadband Strategy with the aim of evaluating the recommendations in the strategy side by side the broadband development in Ghana. The researchers conducted interviews both officially and unofficially with ICT stakeholders, made observations, studied Government...... publications and sourced information from the internet in order to find out the extent of broadband development in Ghana. A SWOT analysis is carried out to determine the strengths, weaknesses, opportunities and threat to the development of broadband market in Ghana. The facilitation, regulatory and market...... the market. It is the hope of the researchers that this academic exercise will be useful to anyone who wishes to study the policy effect on the Ghanaian telecommunications market and the Ghanaian approach to Universal Access and Service....

  15. Analyzing Broadband Divide in the Farming Sector

    DEFF Research Database (Denmark)

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

    2013-01-01

    Agriculture industry has been evolving for centuries. Currently, the technological development of Internet oriented farming tools allows to increase the productivity and efficiency of this sector. Many of the already available tools and applications require high bandwidth in both directions......, upstream and downstream connection. The main constraint is that farms are naturally located in rural areas where the required access broadband data rates are not available. This paper studies the broadband divide in relation to the Danish agricultural sector. Results show how there is an important...... difference between the broadband availability for farms and the rest of the households/buildings the country. This divide may be slowing down the potential technological development of the farming industry, in order to keep their competitiveness in the market. Therefore, broadband development in rural areas...

  16. Wireless Broadband Access and Accounting Schemes

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

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

  17. Nanophotonic Design for Broadband Light Management

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-10-13

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

  18. Broadband unidirectional cloak designed by eikonal theory.

    Science.gov (United States)

    Liu, Xuan; Wu, Xiaojia; Zhang, Luoning; Zhou, Jing

    2015-11-02

    A method for designing optical device is derived based on the eikonal theory, which could obtain the eikonal distribution on a curved surface according to the propagation characteristics of the subsequent light wave. Then combining with the phase matching condition, we designed a broadband unidirectional cloak. Different from the reported unidirectional cloaks, the proposed one could be used for coherent wave and has continuous broadband performance. Moreover, it has three cloaked regions. Full-wave simulation results verify the properties of the cloak.

  19. Multi-Mode Broadband Patch Antenna

    Science.gov (United States)

    Romanofsky, Robert R. (Inventor)

    2001-01-01

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

  20. Is European Broadband Ready for Smart Grid?

    DEFF Research Database (Denmark)

    Balachandran, Kartheepan; Pedersen, Jens Myrup

    2014-01-01

    In this short paper we compare the communication requirements for three Smart Grid scenarios with the availability of broadband and mobile communication networks in Europe. We show that only in the most demanding case - where data is collected and transmitted every second - a standard GSM....../GPRS connection is not enough. Whereas in the less demanding scenarios it is almost all of the European households that can be covered by a standard broadband technology for use with Smart Grid....

  1. Broadband mode conversion via gradient index metamaterials.

    Science.gov (United States)

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

    2016-04-21

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

  2. Broadband direct RF digitization receivers

    CERN Document Server

    Jamin, Olivier

    2014-01-01

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

  3. Interpreting Flux from Broadband Photometry

    Science.gov (United States)

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

    2016-10-01

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

  4. Delivery of satellite based broadband services

    Science.gov (United States)

    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.

  5. Standardization of broadband radio access networks

    Science.gov (United States)

    Kruys, Jan; Haine, John

    1998-09-01

    This paper introduces the ETSI Project on Broadband Radio Access Networks (EP-BRAN). BRAN systems will be used for local area applications with limited mobility (HIPERLAN/2); fixed access with area coverage in urban and rural areas (HIPERACCESS); and short range high-speed point-to-point links (HIPERLINK). They will support transport of either IP or ATM protocols, supporting managed quality of service. Such systems are needed to provide access to the future broadband core networks supporting multi-media applications. The paper addresses the motivation and market demand for broadband radio access networks, the objectives and scope of the Project, the operational and technical requirements, the types of networks to be standardized, the scope of the standards, the issue of spectrum and the Project schedule.

  6. Magnetically levitated autoparametric broadband vibration energy harvesting

    Science.gov (United States)

    Kurmann, L.; Jia, Y.; Manoli, Y.; Woias, P.

    2016-11-01

    Some of the lingering challenges within the current paradigm of vibration energy harvesting (VEH) involve narrow operational frequency range and the inevitable non-resonant response from broadband noise excitations. Such VEHs are only suitable for limited applications with fixed sinusoidal vibration, and fail to capture a large spectrum of the real world vibration. Various arraying designs, frequency tuning schemes and nonlinear vibratory approaches have only yielded modest enhancements. To fundamentally address this, the paper proposes and explores the potentials in using highly nonlinear magnetic spring force to activate an autoparametric oscillator, in order to realize an inherently broadband resonant system. Analytical and numerical modelling illustrate that high spring nonlinearity derived from magnetic levitation helps to promote the 2:1 internal frequency matching required to activate parametric resonance. At the right internal parameters, the resulting system can intrinsically exhibit semi-resonant response regardless of the bandwidth of the input vibration, including broadband white noise excitation.

  7. Service Differentiation in Residential Broadband Networks

    DEFF Research Database (Denmark)

    Sigurdsson, Halldór Matthias

    2004-01-01

    As broadband gains widespread adoption with residential users, revenue generating voice- and video-services have not yet taken off. This slow uptake is often attributed to lack of Quality of Service management in residential broadband networks. To resolve this and induce service variety, network...... access providers are implementing service differentiation in their networks where voice and video gets prioritised before data. This paper discusses the role of network access providers in multipurpose packet based networks and the available migration strategies for supporting multimedia services...... in digital subscriber line (DSL) based residential broadband networks. Four possible implementation scenarios and their technical characteristics and effects are described. To conclude, the paper discusses how network access providers can be induced to open their networks for third party service providers....

  8. Participation in the broadband society in Denmark

    DEFF Research Database (Denmark)

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

    2009-01-01

    The purpose of the paper is to provide an empirical overview of broadband developments in Denmark. The overview includes sections on coverage and penetration, connection speeds, retail prices, competition, interconnection prices, and residential access to Internet. The documentation shows that De...... explanation is not that they cannot afford it but that they don't need it. Still, there is an issue with respect to the participation in the broadband society, when an increasing part of communications in society is based on the Internet....

  9. Broadband Polarizers Based on Graphene Metasurfaces

    CERN Document Server

    Guo, Tianjing

    2016-01-01

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

  10. A polarization-independent broadband terahertz absorber

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Cheng; Zang, XiaoFei, E-mail: xfzang@usst.edu.cn, E-mail: ymzhu@usst.edu.cn; Wang, YiQiao; Chen, Lin; Cai, Bin; Zhu, YiMing, E-mail: xfzang@usst.edu.cn, E-mail: ymzhu@usst.edu.cn [Shanghai Key Laboratory of Modern Optical System and Engineering Research Center of Optical Instrument and System, Ministry of Education, University of Shanghai for Science and Technology, Shanghai 200093 (China)

    2014-07-21

    A highly efficient broadband terahertz absorber is designed, fabricated, and experimentally as well as theoretically evaluated. The absorber comprises a heavily doped silicon substrate and a well-designed two-dimensional grating. Due to the destructive interference of waves and diffraction, the absorber can achieve over 95% absorption in a broad frequency range from 1 to 2 THz and for angles of incidence from 0° to 60°. Such a terahertz absorber is also polarization-independent due to its symmetrical structure. This omnidirectional and broadband absorber have potential applications in anti-reflection coatings, imaging systems, and so on.

  11. Noise radar with broadband microwave ring correlator

    Science.gov (United States)

    Susek, Waldemar; Stec, Bronislaw

    2011-06-01

    A principle of quadrature correlation detection of noise signals using an analog broadband microwave correlator is presented in the paper. Measurement results for the correlation function of noise signals are shown and application of such solution in the noise radar for precise determination of distance changes and velocity of these changes is also presented. Results for short range noise radar operation are presented both for static and moving objects. Experimental results using 2,6 - 3,6 GHz noise like waveform for the signal from a breathing human is presented. Conclusions and future plans for applications of presented detection technique in broadband noise radars bring the paper to an end.

  12. VT Total Broadband Availability by Census Block - 06-2013

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201306 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2013. This...

  13. VT Public Locations of Broadband Data - 06-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201106 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2011. This...

  14. VT Public Locations of Broadband Data - 06-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201006 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2010. This...

  15. VT Total Broadband Availability by Census Block - 06-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201106 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2011. This...

  16. VT Cable Broadband Availability by Census Block - 06-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201006 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2010. This...

  17. VT Cable Broadband Availability by Census Block - 12-2012

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201212 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2012. This...

  18. VT Wireless Broadband Availability by Census Block - 06-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201006 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2010. This...

  19. VT Total Broadband Availability by Census Block - 06-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201006 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2010. This...

  20. VT Wireline Broadband Availability by Census Block - 06-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201006 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2010. This...

  1. VT Detailed Broadband Availability by Census Block -12-2012

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201212 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2012. This...

  2. VT DSL Broadband Availability by Census Block - 06-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201106 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2011. This...

  3. VT Detailed Broadband Availability by Census Block -12-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201112 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2011. This...

  4. VT Wireline Broadband Availability by Census Block - 12-2012

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201212 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2012. This...

  5. VT Cable Broadband Availability by Census Block - 12-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201112 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2011. This...

  6. VT Detailed Broadband Availability by Census Block - 06-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201006 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2010. This...

  7. VT Detailed Broadband Availability by Census Block - 06-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201106 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2011. This...

  8. VT DSL Broadband Availability by Census Block - 12-2012

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201212 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2012. This...

  9. VT Total Broadband Availability by Census Block - 12-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201112 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2011. This...

  10. VT Wireline Broadband Availability by Census Block - 12-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201112 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2011. This...

  11. VT Public Locations of Broadband Data - 12-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201012 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2010. This...

  12. VT Wireless Broadband Availability by Census Block - 12-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201012 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2010. This...

  13. VT DSL Broadband Availability by Census Block - 12-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201012 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2010. This...

  14. VT Detailed Broadband Availability by Census Block - 12-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201012 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2010. This...

  15. VT Wireline Broadband Availability by Census Block - 06-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201106 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2011. This...

  16. VT Cable Broadband Availability by Census Block - 12-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201012 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2010. This...

  17. VT Wireless Broadband Availability by Census Block - 12-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201112 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2011. This...

  18. VT Wireless Broadband Availability by Census Block - 12-2012

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201212 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2012. This...

  19. VT Public Locations of Broadband Data - 12-2012

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201212 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2012. This...

  20. VT Wireline Broadband Availability by Census Block - 12-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201012 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2010. This...

  1. VT Cable Broadband Availability by Census Block - 06-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201106 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2011. This...

  2. VT DSL Broadband Availability by Census Block - 12-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201112 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2011. This...

  3. VT Total Broadband Availability by Census Block - 12-2012

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201212 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2012. This...

  4. VT DSL Broadband Availability by Census Block - 06-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201006 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2010. This...

  5. VT Total Broadband Availability by Census Block - 12-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201012 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2010. This...

  6. VT Public Locations of Broadband Data - 12-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201112 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2011. This...

  7. VT Wireless Broadband Availability by Census Block - 06-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201106 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2011. This...

  8. Change in triple play requirements and evolving broadband networks

    NARCIS (Netherlands)

    Wolfswinkel, R.N. van

    2005-01-01

    In the current broadband market there are many new developments regarding both services and the broadband infrastructures carrying those services. This paper will address what the requirements of services are towards broadband networks and how this will evolve over time. The focus will be on the req

  9. Requirements of triple play services towards broadband access networks

    NARCIS (Netherlands)

    Wolfswinkel, R.N. van

    2005-01-01

    In the current broadband market there are many new developments regarding both services and the broadband infrastructures carrying those services. This paper will address what the requirements of services are towards broadband networks. The focus will be on the requirements of triple play related se

  10. EMERGING BROADBAND WIRELESS TECHNOLOGIES: WIFI AND WIMAX

    Directory of Open Access Journals (Sweden)

    Rama K. Raju

    2012-07-01

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

  11. A THEORY FOR BROADBAND VARACTOR PARAMETRIC AMPLIFIERS

    Science.gov (United States)

    design and synthesis of broadband varactor parametric amplifiers. The circuit considered in this thesis is that of linear variable capacitors embedded...second and more important inherent property is that, due to the frequency-coupling action of the variable capacitor , the scattering coefficient at the

  12. Broadband Satellite Technologies and Markets Assessed

    Science.gov (United States)

    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.

  13. The GREGOR Broad-Band Imager

    Science.gov (United States)

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

    2012-11-01

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

  14. FMCW Radar with Broadband Communication Capability

    NARCIS (Netherlands)

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

    2007-01-01

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

  15. BROADBAND TRAVELLING WAVE SEMICONDUCTOR OPTICAL AMPLIFIER

    DEFF Research Database (Denmark)

    2010-01-01

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

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

    CERN Document Server

    Choudrie, Jyoti

    2013-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Yoshio Arai

    2014-03-01

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

  18. Broadband DOA Estimation Based on Nested Arrays

    Directory of Open Access Journals (Sweden)

    Zhi-bo Shen

    2015-01-01

    Full Text Available Direction of arrival (DOA estimation is a crucial problem in electronic reconnaissance. A novel broadband DOA estimation method utilizing nested arrays is devised in this paper, which is capable of estimating the frequencies and DOAs of multiple narrowband signals in broadbands, even though they may have different carrier frequencies. The proposed method converts the DOA estimation of multiple signals with different frequencies into the spatial frequency estimation. Then, the DOAs and frequencies are pair matched by sparse recovery. It is possible to significantly increase the degrees of freedom (DOF with the nested arrays and the number of sources can be more than that of sensor array. In addition, the method can achieve high estimation precision without the two-dimensional search process in frequency and angle domain. The validity of the proposed method is verified by theoretic analysis and simulation results.

  19. Broadband Visible Light Induced NO Formation

    Science.gov (United States)

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

    2009-06-01

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

  20. Inverse Doppler Effects in Broadband Acoustic Metamaterials

    Science.gov (United States)

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

    2016-08-01

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

  1. Broad-band acoustic hyperbolic metamaterial

    CERN Document Server

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

    2015-01-01

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

  2. Inverse Doppler Effects in Broadband Acoustic Metamaterials.

    Science.gov (United States)

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

    2016-08-31

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

  3. Random Lasers for Broadband Directional Emission

    CERN Document Server

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

    2016-01-01

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

  4. Broadband Phase Spectroscopy over Turbulent Air Paths.

    Science.gov (United States)

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

    2015-09-01

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

  5. An ultra-broadband multilayered graphene absorber

    KAUST Repository

    Amin, Muhammad

    2013-01-01

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

  6. A 12 GHz broadband latching circulator

    Science.gov (United States)

    Katoh, Y.; Konishi, H.; Sakamoto, K.

    The two kinds of latching circulators, external return path and internal return path, are defined, noting the advantages (faster switching speed, lower switching energy, less complicated fabrication) offered by the internal configuration. It is noted, however, that this kind of circulator is difficult to make broadband because the return paths do not seem to act as part of the ferrite junction. The development of a 12-GHz broadband, internal return path circulator with impedance matching transformer and in-phase adjustment screws designed using eigenvalue measurement is described. In describing the operating characteristics, it is noted that more than 25 dB isolation over 11 GHz to 13.5 GHz and 0.25 dB insertion loss is obtained.

  7. Broadband S-band class E HPA

    NARCIS (Netherlands)

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

    2009-01-01

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

  8. Broadband S-band Class E HPA

    NARCIS (Netherlands)

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

    2009-01-01

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

  9. Broadband luminescence in liquid-solid transition

    CERN Document Server

    Achilov, M F; Trunilina, O V

    2002-01-01

    Broadband luminescence (BBL) intensity behavior in liquid-solid transition in polyethyleneglycol-600 has been established. Oscillation of BBL intensity observed in liquid-polycrystal transition are not found to observed in liquid-amorphous solid transition. It is shown that application of the theory of electron state tails to interpretation of BBL spectral properties in liquids demands restriction. BBL spectroscopy may be applied for optimization of preparation of polymers with determined properties. (author)

  10. Enhanced broadband optical transmission in metallized woodpiles

    DEFF Research Database (Denmark)

    Malureanu, Radu; Alabastri, A.; Cheng, W.;

    2011-01-01

    We present an optimized isotropic metal deposition technique used for covering three-dimensional polymer structures with a 50 nm smooth silver layer. The technology allows fast and isotropic coating of complex 3D dielectric structures with thin silver layers. Transmission measurements of 3D...... metallized woodpiles reveal a new phenomenon of enhanced optical transmission in broadband range (up to 300 nm) in the near IR....

  11. Metamaterial Coatings for Broadband Asymmetric Mirrors

    CERN Document Server

    Chen, A; Hasegawa, K; Podolskiy, V A; Chen, Aiqing; Deutsch, Miriam; Hasegawa, Keisuke; Podolskiy, Viktor A.

    2006-01-01

    We report on design and fabrication of nano-composite metal-dielectric thin film coatings with high reflectance asymmetries. Applying basic dispersion engineering principles to model a broadband and large reflectance asymmetry, we obtain a model dielectric function for the metamaterial film, closely resembling the effective permittivity of disordered metal-dielectric nano-composites. Coatings realized using disordered nanocrystalline silver films deposited on glass substrates confirm the theoretical predictions, exhibiting symmetric transmittance, large reflectance asymmetries and a unique flat reflectance asymmetry.

  12. Broadband Spectroscopy of Nanoporous-Gold Promoter

    Directory of Open Access Journals (Sweden)

    S. K. Nakatani

    2014-02-01

    Full Text Available The efficiency of UV photocatalysis on TiO2 particles was increased by mixing TiO2 particles with nanoporous gold (NPG with pore diameters of 10–40 nm. This means that NPG acts as a promoter in the photocatalytic reaction of TiO2. Broadband spectroscopic results from millimeter wave to ultra violet of NPG membrane are discussed to estimate plasmonic effect on the catalysis.

  13. Diagonalizing sensing matrix of broadband RSE

    Science.gov (United States)

    Sato, Shuichi; Kokeyama, Keiko; Kawazoe, Fumiko; Somiya, Kentaro; Kawamura, Seiji

    2006-03-01

    For a broadband-operated RSE interferometer, a simple and smart length sensing and control scheme was newly proposed. The sensing matrix could be diagonal, owing to a simple allocation of two RF modulations and to a macroscopic displacement of cavity mirrors, which cause a detuning of the RF modulation sidebands. In this article, the idea of the sensing scheme and an optimization of the relevant parameters will be described.

  14. Design and fabrication of broadband rugate filter

    Institute of Scientific and Technical Information of China (English)

    Zhaug Jun-Chao; Fang Ming; Shao Yu-Chuan; Jin Yun-Xia; He Hong-Bo

    2012-01-01

    The design and the deposition of a rugate filter for broadband applications are discussed.The bandwidth is extended by increasing the rugate period continuously with depth.The width and the smoothness of the reflection band with the distribution of the periods are investigated.The improvement of the steepness of the stopband edges and the suppression of the side lobes in the transmission zone are realized by adding two apodized rugate structures with fixed periods at the external broadband rngate filter interfaces.The rapidly alternating deposition technology is used to fabricate a rugate filter sample.The measured transmission spectrum with a reflection bandwidth of approximately 505 nm is close to that of the designed broadband rugate filter except a transmittance peak in the stopband.Based on the analysis of the cross-sectional scanning electron microscopic image of the sample,it is found that the transmission peak is most likely to be caused by the instability of the deposition rate.

  15. Broadband electromagnetic analysis of compacted kaolin

    Science.gov (United States)

    Bore, Thierry; Wagner, Norman; Cai, Caifang; Scheuermann, Alexander

    2017-01-01

    The mechanical compaction of soil influences not only the mechanical strength and compressibility but also the hydraulic behavior in terms of hydraulic conductivity and soil suction. At the same time, electric and dielectric parameters are increasingly used to characterize soil and to relate them with mechanic and hydraulic parameters. In the presented study electromagnetic soil properties and suction were measured under defined conditions of standardized compaction tests. The impact of external mechanical stress conditions of nearly pure kaolinite was analyzed on soil suction and broadband electromagnetic soil properties. An experimental procedure was developed and validated to simultaneously determine mechanical, hydraulic and broadband (1 MHz-3 GHz) electromagnetic properties of the porous material. The frequency dependent electromagnetic properties were modeled with a classical mixture equation (advanced Lichtenecker and Rother model, ALRM) and a hydraulic-mechanical-electromagnetic coupling approach was introduced considering water saturation, soil structure (bulk density, porosity), soil suction (pore size distribution, water sorption) as well as electrical conductivity of the aqueous pore solution. Moreover, the relaxation behavior was analyzed with a generalized fractional relaxation model concerning a high-frequency water process and two interface processes extended with an apparent direct current conductivity contribution. The different modeling approaches provide a satisfactory agreement with experimental data for the real part. These results show the potential of broadband electromagnetic approaches for quantitative estimation of the hydraulic state of the soil during densification.

  16. Pacific Array (Transportable Broadband Ocean Floor Array)

    Science.gov (United States)

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

    2016-04-01

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

  17. Incoherent broadband optical pulse generation using an optical gate

    Institute of Scientific and Technical Information of China (English)

    Biao Chen; Qiong Jiang

    2008-01-01

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

  18. Broadband tonpilz underwater acoustic transducers based on multimode optimization

    OpenAIRE

    Yao, Qingshan; Jensen, Leif Bjørnø

    1997-01-01

    Head flapping has often been considered to be deleterious for obtaining a tonpilz transducer with broadband, high power performance. In the present work, broadband, high power tonpilz transducers have been designed using the finite element (FE) method. Optimized vibrational modes including the flapping mode of the head are effectively used to achieve the broadband performance. The behavior of the transducer in its longitudinal piston mode and in its flapping mode is analysed for in-air and in...

  19. Investigation of broadband digital predistortion for broadband radio over fiber transmission systems

    Science.gov (United States)

    Zhang, Xiupu; Liu, Taijun; Shen, Dongya

    2016-12-01

    In future broadband cloud radio access networks (C-RAN), front-haul transmission systems play a significant role in performance and cost of C-RAN. Broadband and high linearity radio over fiber (RoF) transmission systems are considered a promising solution for the front-haul. Digital linearization is one possible solution for RoF front-haul. In this paper, we investigate RF domain digital predistortion (DPD) linearization for broadband RoF front-haul. The implemented DPD is first investigated in 2.4 GHz WiFi over fiber transmission systems at 36 Mb/s, and more than 8-dB and 5.6-dB improvements of error vector magnitude (EVM) are achieved in back to back (BTB) and after 10 km single mode fiber (SMF) transmission. Further, both WiFi and ultra wide band (UWB) wireless signals are transmitted together, in which the DPD has linearization bandwidth of 2.4 GHz. It is shown that the implemented DPD leads to EVM improvements of 4.5-dB (BTB) and 3.1-dB (10 km SMF) for the WiFi signal, and 4.6-dB (BTB) and 4-dB (10 km SMF) for the broadband UWB signal.

  20. A novel broadband waterborne acoustic absorber

    Science.gov (United States)

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

    2016-07-01

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

  1. Source of broadband Jovian Kilometric radiation

    Energy Technology Data Exchange (ETDEWEB)

    Jones, D.; Leblanc, Y.

    1987-02-01

    Broadband Jovian Kilometric radiation was observed by Voyagers 1 and 2 to be beamed away from the zenomagnetic equatorial plane. Two theories were proposed for the equatorial shadow zone. One suggested that Io plasma torus forms an obstacle to radiation produced on auroral field lines. The other theory proposed that the source is located on the outer flanks of the torus, the beaming being inherent to the emission mechanism. Results are presented which indicate that the latter is consistent with the observations and it would appear that the emission is produced by linear mode conversion of electrostatic upper hybrid to electromagnetic waves in plasma density gradients.

  2. Optical broadband monitoring of thin film growth

    Institute of Scientific and Technical Information of China (English)

    H.Ehlers; T.Groβ; M.Lappschies; D.Ristau

    2005-01-01

    This contribution is focused on applications of spectroscopic methods for the precise control of deposition processes. In this context, the present study gives a review on selected combinations of conventional and ion deposition techniques with different broadband online spectrophotometric systems. Besides two systems operating in the VIS- and NIR-spectral range in combination with ion processes, also a monochromator system developed for conventional deposition processes in the DUV/VUV-spectral range will be discussed. The considerations will be concluded by a comparison of the major advantages of the specific combinations of processes with online monitoring concepts and by a brief outlook concerning future challenges.

  3. Fibre laser based broadband THz imaging systems

    DEFF Research Database (Denmark)

    Eichhorn, Finn

    State-of-the-art optical fiber technology can contribute towards complex multi-element broadband terahertz imaging systems. Classical table-top terahertz imaging systems are generally limited to a single emitter/receiver pair, which constrains their imaging capability to tedious raster scanning...... imaging techniques. This thesis exhibits that fiber technology can improve the robustness and the flexibility of terahertz imaging systems both by the use of fiber-optic light sources and the employment of optical fibers as light distribution medium. The main focus is placed on multi-element terahertz...

  4. Broadband acoustic properties of a murine skull.

    Science.gov (United States)

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

    2016-03-07

    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.

  5. Broadband surface-wave transformation cloak

    Science.gov (United States)

    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

  6. A Design of Double Broadband MIMO Antenna

    Directory of Open Access Journals (Sweden)

    Yanfeng Geng

    2015-01-01

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

  7. Evaluation of arctic broadband surface radiation measurements

    Directory of Open Access Journals (Sweden)

    N. Matsui

    2011-08-01

    Full Text Available 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.

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

    Institute of Scientific and Technical Information of China (English)

    YANG Kunde; MA Yuanliang

    2003-01-01

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

  9. Broadband Liner Optimization for the Source Diagnostic Test Fan

    Science.gov (United States)

    Nark, Douglas M.; Jones, Michael G.

    2012-01-01

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

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

    DEFF Research Database (Denmark)

    Falch, Morten; Tadayoni, Reza; Henten, Anders

    2015-01-01

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

  11. Silicon graphene waveguide tunable broadband microwave photonics phase shifter

    CERN Document Server

    Capmany, Jose; Muñoz, Pascual

    2013-01-01

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

  12. Techno-economic evaluation of broadband access technologies

    DEFF Research Database (Denmark)

    Sigurdsson, Halldór Matthias; Skouby, Knud Erik

    2005-01-01

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

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

    Science.gov (United States)

    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…

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

    Science.gov (United States)

    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 in…

  15. OFDM Towards Fixed and Mobile Broadband Wireless Access

    DEFF Research Database (Denmark)

    Shanker Jha, Uma; Prasad, Ramjee

    of mobile broadband wireless access and the standards developed by the IEEE 802.16 standards organization. The book gives practitioners a solid understaning of: Basic requirements of fixed and mobile broadband access technologies. Fundamentals of orthogonal frequency division multiplexing (OFDM...

  16. Mammoth Mountain, California broadband seismic experiment

    Science.gov (United States)

    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

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

    Science.gov (United States)

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

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

  18. Modeling the broadband persistent emission of magnetars

    CERN Document Server

    Zane, Silvia; Nobili, Luciano; Rea, Nanda

    2010-01-01

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

  19. Resource Management in Broadband Communication Networks

    DEFF Research Database (Denmark)

    Hansen, Mads Stenhuus

    2003-01-01

    This thesis - Resource Management in Broadband Communication Networks - deals with different ways of optimizing the available resources of data- or telecommunication networks. Especially topics like optimal routing, load balancing and fast recovery of routes in case of link failures are covered...... in communication networks. For instance, the results show that a network controlled by simulated ants can balance the load quickly and efficiently, thereby postponing local hot-spots or in some cases even avoid hot-spots. Furthermore, the results clearly demonstrate, that systems using simulated ants obtain...... a virtually unprecedented robustness. A network with failing components typically return to a fully operational state within seconds or even faster. Hopefully these results of the investigation of simulated ants - along with other results from the literature - can contribute to make the big manufacturers...

  20. Tunable Broadband Printed Carbon Transparent Conductor

    Science.gov (United States)

    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.

  1. Broadband interferometer observations of a triggered lightning

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

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

  2. Hot Carrier extraction with plasmonic broadband absorbers

    CERN Document Server

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

    2016-01-01

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

  3. Broadband Spectral Study of Magnetar Bursts

    Science.gov (United States)

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

    2016-07-01

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

  4. Superconducting Quantum Arrays for Broadband RF Systems

    Science.gov (United States)

    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.

  5. Broadband phase-preserved optical elevator

    CERN Document Server

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

    2011-01-01

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

  6. Broadband optical cooling of molecular rotors

    CERN Document Server

    Lien, Chien-Yu; Odom, Brian C

    2014-01-01

    Contrary to intuition, resonant laser excitation of bound electrons can decrease the temperature of a system, with electronic relaxation times as fast as nanoseconds allowing for rapid cooling to far below ambient temperature. Although laser cooling of atoms is routine owing to their relatively simple internal structure, laser cooling of molecular translational speeds, vibrations, or rotations is challenging because a different laser frequency is required to electronically excite each populated vibrational and rotational state. Here, we show that molecules with decoupled vibrational and electronic modes can be rotationally cooled using a single spectrally filtered broadband laser to simultaneously address many rotational states. We optically cool AlH$^+$ ions held in a room-temperature radiofrequency Paul trap to collect 96% of the population in the ground quantum state, corresponding to a rotational temperature of 4 K. In our current implementation, parity-preserving electronic cycling cools to the two lowes...

  7. Broadband acoustic cloak for ultrasound waves.

    Science.gov (United States)

    Zhang, Shu; Xia, Chunguang; Fang, Nicholas

    2011-01-14

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

  8. Future large broadband switched satellite communications networks

    Science.gov (United States)

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

    1979-01-01

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

  9. Frequency Doubling Broadband Light in Multiple Crystals

    Energy Technology Data Exchange (ETDEWEB)

    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.

  10. Modeling Broadband motions from the Tohoku earthquake

    Science.gov (United States)

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

    2011-12-01

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

  11. Broadband plasmon induced transparency in terahertz metamaterials

    KAUST Repository

    Zhu, Zhihua

    2013-04-25

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

  12. Policy factors affecting broadband development in Poland

    DEFF Research Database (Denmark)

    Henten, Anders; Windekilde, Iwona Maria

    2014-01-01

    is to reduce the gap between Poland and other EU Member Countries in the area of the development and implementation of information and communication technologies. However, Poland’s accession to the European Union and the implementation of EU regulation mechanisms accelerate the integration of Poland...... – with the ‘lightest’forms of intervention first and the ‘strongest’at the end. Furthermore, empirical evidence on the developments in access technologies and the policy initiatives taken by the Polish government are presented. Finally, there is a conclusion regarding the importance of the different types of public......Poland joined the EU in 2004 and still has one of the Europe’s least developed information societies. Broadband penetration in Poland is still amongst the lowest in the EU and significantly below the EU average. Considering the present state of information technology, the key challenge for Poland...

  13. Hollow glass waveguides for broadband infrared transmission.

    Science.gov (United States)

    Abel, T; Hirsch, J; Harrington, J A

    1994-07-15

    Broadband hollow glass waveguides have been fabricated with losses as low as 0.15 dB/m at 10.6 microm. We make these hollow glass waveguides by coating the inside of polyimide-coated silica-glass tubing with a metallic layer followed by a thin dielectric coating of a metal halide. The bore sizes of the guides range from 320 to 700 microm, and we have made lengths as long as 3 m. The bending radii of the waveguides are less than 5 cm for bore sizes less than 500 microm. We have used these waveguides to deliver greater than 80 W of CO(2) laser power and 5 W of Er:YAG laser power. The hollow glass guides are inexpensive, robust, and quite flexible and therefore a good infrared fiber for power and sensor applications.

  14. Broadband Dielectric Spectroscopy on Human Blood

    CERN Document Server

    Wolf, M; Lunkenheimer, P; Loidl, A

    2011-01-01

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

  15. QR Factorization for the Cell Broadband Engine

    Directory of Open Access Journals (Sweden)

    Jakub Kurzak

    2009-01-01

    Full Text Available The QR factorization is one of the most important operations in dense linear algebra, offering a numerically stable method for solving linear systems of equations including overdetermined and underdetermined systems. Modern implementations of the QR factorization, such as the one in the LAPACK library, suffer from performance limitations due to the use of matrix–vector type operations in the phase of panel factorization. These limitations can be remedied by using the idea of updating of QR factorization, rendering an algorithm, which is much more scalable and much more suitable for implementation on a multi-core processor. It is demonstrated how the potential of the cell broadband engine can be utilized to the fullest by employing the new algorithmic approach and successfully exploiting the capabilities of the chip in terms of single instruction multiple data parallelism, instruction level parallelism and thread-level parallelism.

  16. Techno-Economics of Residential Broadband Deployment

    DEFF Research Database (Denmark)

    Sigurdsson, Halldor Matthias

    2007-01-01

    on account of their existing telecom network (”the raw copper”), and typically they will prefer an xDSL-based strategy (various types of Digital Subscriber Line-technology: ADSL, VDSL, etc.), where the rate of speed of data connections are increased gradually to 10-50 Mbit/s or even more, in order to gain...... as much profit as possible from their previous investments. However, the operators are not restricted by these considerations, and they will often choose a fiber-to-the home solution (FTTH, Fiber-to-the-Home), which will offer a far more substantial data capacity in the long run. The choice of the proper...... broadband deployment strategy is depending on a complexed set of parameters, and there is a demand for precise techno-economic cost models estimating financial feasibility. The existing cost models do not consider the dynamic developments in the market caused by competition. The PhD thesis has a profound...

  17. Energy Efficient Evolution of Mobile Broadband Networks

    DEFF Research Database (Denmark)

    Micallef, Gilbert

    costs, which, based on increasing energy prices and necessary network upgrades are likely to increase. Since base station sites make up for about 75% of the power consumption in mobile networks, studies are focused on this specific network element. A number of factors believed to play a role...... the v impact of replacing old equipment. Results show that an aggressive replacement strategy and the upgrade of sites to remote radio head can restrain the increase in power consumption of the network to just 17%. In addition to upgrading equipment, mobile network operators can further reduce power...... network capacity evolution path, replacing old and less efficient equipment, and enabling power saving features, can all considerably reduce the power consumption of future mobile broadband networks. Studies and recommendations presented within this thesis demonstrate that it is realistic for mobile...

  18. Broadband Nonlinear Signal Processing in Silicon Nanowires

    DEFF Research Database (Denmark)

    Yvind, Kresten; Pu, Minhao; Hvam, Jørn Märcher;

    The fast non-linearity of silicon allows Tbit/s optical signal processing. By choosing suitable dimensions of silicon nanowires their dispersion can be tailored to ensure a high nonlinearity at power levels low enough to avoid significant two-photon abso We have fabricated low insertion and propa......The fast non-linearity of silicon allows Tbit/s optical signal processing. By choosing suitable dimensions of silicon nanowires their dispersion can be tailored to ensure a high nonlinearity at power levels low enough to avoid significant two-photon abso We have fabricated low insertion...... and propagation loss silicon nanowires and use them to demonstrate the broadband capabilities of silicon....

  19. Broadband Multifocal Conic-Shaped Metalens

    CERN Document Server

    Bao, Yanjun; Fang, Zheyu

    2016-01-01

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

  20. The broadband spectrum of Centaurus X-3

    Science.gov (United States)

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

    2016-04-01

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

  1. Broadband midinfrared frequency comb with tooth scanning

    Science.gov (United States)

    Lee, Kevin F.; Masłowski, P.; Mills, A.; Mohr, C.; Jiang, Jie; Schunemann, Peter G.; Fermann, M. E.

    2015-03-01

    Frequency combs are a massively parallel source of extremely accurate optical frequencies. Frequency combs generally operate at the visible or near-infrared wavelengths, but fundamental molecular vibrations occur at midinfrared wavelengths. We demonstrate an optically-referenced, broadband midinfrared frequency comb based on a doublyresonant optical parametric oscillator (OPO). By tuning the wavelength of the reference laser, the comb line frequencies are tuned as well. By scanning the reference wavelength, any frequency can be accessed, not just the frequencies of the base comb. Combined with our comb-resolving Fourier transform spectrometer, we can measure 200 wavenumber wide broadband absorption spectra with 200 kHz linewidth comb teeth. Our OPO is pumped by an amplified Tm fiber frequency comb, with phase-locked carrier envelope offset frequency, and repetition rate fixed by phase-locking a frequency comb line to a narrow linewidth diode laser at a telecom channel. The frequency comb is referenced to GPS by long-term stabilization of the repetition rate to a selected value using the temperature of the reference laser as the control. The resulting pump comb is about 3W of 100 fs pulses at 418 MHz repetition rate at 1950 nm. Part of the comb is used for supercontinuum generation for frequency stabilization, and the rest pumps an orientation-patterned gallium arsenide (OP-GaAs) crystal in a doubly-resonant optical parametric oscillator cavity, yielding collinear signal and idler beams from about 3 to 5.5 μm. We verify comb scanning by resolving the 200 MHz wide absorption lines of the entire fundamental CO vibrational manifold at 11 Torr pressure.

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

    Science.gov (United States)

    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.

  3. Broadband tonpilz underwater acoustic transducers based on multimode optimization

    DEFF Research Database (Denmark)

    Yao, Qingshan; Jensen, Leif Bjørnø

    1997-01-01

    Head flapping has often been considered to be deleterious for obtaining a tonpilz transducer with broadband, high power performance. In the present work, broadband, high power tonpilz transducers have been designed using the finite element (FE) method. Optimized vibrational modes including...... the flapping mode of the head are effectively used to achieve the broadband performance. The behavior of the transducer in its longitudinal piston mode and in its flapping mode is analysed for in-air and in-water situations. For the 37.8% bandwidth of the center frequency from 28.5 to 41.8 kHz, the amplitude...

  4. Broadband back grating design for thin film solar cells

    KAUST Repository

    Janjua, Bilal

    2013-01-01

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

  5. Multicarrier Block-Spread CDMA for Broadband Cellular Downlink

    NARCIS (Netherlands)

    Petré, F.; Leus, G.; Moonen, M.; De Man, H.

    2004-01-01

    Effective suppression of multiuser interference (MUI) and mitigation of frequency-selective fading effects within the complexity constraints of the mobile constitute major challenges for broadband cellular downlink transceiver design. Existing wideband direct-sequence (DS) code division multiple acc

  6. Exploiting Narrowband Efficiency for Broadband Convolutive Blind Source Separation

    Directory of Open Access Journals (Sweden)

    Aichner Robert

    2007-01-01

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

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

    Science.gov (United States)

    Zhao, Y; Belkin, M A; Alù, A

    2012-05-29

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

  8. Broadband Reflective Coating Process for Large FUVOIR Mirrors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ZeCoat Corporation will develop and demonstrate a set of revolutionary coating processes for making broadband reflective coatings suitable for very large mirrors (4+...

  9. Broadband Wireless Data Acquisition and Control Device Project

    Data.gov (United States)

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

  10. Economic evaluation of broadband distribution networks to the home

    Science.gov (United States)

    Merk, Charles A.

    1992-02-01

    Economic wideband, linear fiber optic transmitters and receivers pave the way for broadband to the home. The diamond network architecture (DNA) delivers 1 GHz bandwidth. This provides standard video, HDTV, and switched two-way broadband digital services to the home. An economic model is presented using the DNA that considers the impact of digital TV, HDTV, and the evolution of switched voice and data services on a CATV system.

  11. NREL Spectral Standards Development and Broadband Radiometric Calibrations

    Energy Technology Data Exchange (ETDEWEB)

    Myers, D. R.; Andreas, A.; Stoffel, T.; Reda, I.; Wilcox, S.; Gotseff, P.; Kay, B.; Gueymard, C.

    2003-05-01

    We describe a final version of revisions to current ASTM reference standard spectral distributions used to evaluate photovoltaic device performance. An NREL-developed graphical user interface for working with the SMARTS2 spectral model has been developed and is being tested. A proposed ASTM reference Ultraviolet (UV) spectra for materials durability is presented. Improvements in broadband outdoor radiometer calibration, characterization, and reporting software reduce uncertainties in broadband radiometer calibrations.

  12. Peer to peer networking in Ethernet broadband access networks

    OpenAIRE

    Damola, Ayodele

    2005-01-01

    The use of peer-to-peer (P2P) applications is growing dramatically, particularly for sharing content such as video, audio, and software. The traffic generated by these applications represents a large proportion of Internet traffic. For the broadband access network providers P2P traffic presents several problems. This thesis identifies the performance and business issues that P2P traffic has on broadband access networks employing the McCircuit separation technique. A mechanism for managing P2P...

  13. Estimation of broadband surface emissivity from narrowband emissivities.

    Science.gov (United States)

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

    2011-01-01

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

  14. Broadband monitoring simulation with massively parallel processors

    Science.gov (United States)

    Trubetskov, Mikhail; Amotchkina, Tatiana; Tikhonravov, Alexander

    2011-09-01

    Modern efficient optimization techniques, namely needle optimization and gradual evolution, enable one to design optical coatings of any type. Even more, these techniques allow obtaining multiple solutions with close spectral characteristics. It is important, therefore, to develop software tools that can allow one to choose a practically optimal solution from a wide variety of possible theoretical designs. A practically optimal solution provides the highest production yield when optical coating is manufactured. Computational manufacturing is a low-cost tool for choosing a practically optimal solution. The theory of probability predicts that reliable production yield estimations require many hundreds or even thousands of computational manufacturing experiments. As a result reliable estimation of the production yield may require too much computational time. The most time-consuming operation is calculation of the discrepancy function used by a broadband monitoring algorithm. This function is formed by a sum of terms over wavelength grid. These terms can be computed simultaneously in different threads of computations which opens great opportunities for parallelization of computations. Multi-core and multi-processor systems can provide accelerations up to several times. Additional potential for further acceleration of computations is connected with using Graphics Processing Units (GPU). A modern GPU consists of hundreds of massively parallel processors and is capable to perform floating-point operations efficiently.

  15. Broadband Spectral Analysis of Aql X-1

    CERN Document Server

    Raichur, H; Dewangan, G

    2011-01-01

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

  16. Hollow plasmonic antennas for broadband SERS spectroscopy.

    Science.gov (United States)

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

    2015-01-01

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

  17. Broadband Acoustic Cloak for Ultrasound Waves

    CERN Document Server

    Zhang, Shu; Fang, Nicholas

    2010-01-01

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

  18. Broadband Linear Polarization of Jupiter Trojans

    CERN Document Server

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

    2016-01-01

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

  19. Silver conical helix broadband plasmonic nanoantenna

    Science.gov (United States)

    Sobhkhiz, Nader; Moshaii, Ahmad

    2014-01-01

    The discrete dipole approximation method is used to investigate the optical extinction spectra and the electric field enhancement of Ag conical helix (CH) nanostructures. Based on an expected similarity between the radio frequency response of the antenna with the infrared and the visible response of the nanoantenna, the Ag CH nanostructures were designed as a broadband nanoantenna. It is shown that with engineering the structure parameters of the CH nanostructure the plasmonic response of the nanostructure can be designed for a desirable application. In addition, the change of the substrate material for the nanohelix growth is shown to have infinitesimal effect on the resonance peaks of the conical nanohelix. However, varying the surrounding medium can lead to considerable red-shifting of the plasmonic resonance peaks (up to 230 nm). Calculations of the near field around the helical nanoantenna show that the smaller and the larger sides of the CH are related to the plasmonic resonance peaks at low and high wavelengths, respectively. The calculation result for the extinction spectrum has also been compared with similar experimental data for a 2-pitch Ag conical nanohelix and a relatively good agreement between the numerical calculation and the experiment has been obtained.

  20. Broadband Observations of High Redshift Blazars

    CERN Document Server

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

    2016-01-01

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

  1. Broadband Infrared Heterodyne Spectrometer: Final Report

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-12-16

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

  2. Broadband access technology for passive optical network

    Science.gov (United States)

    Chi, Sien; Yeh, Chien-Hung; Chow, Chi-Wai

    2009-01-01

    We will introduce four related topics about fiber access network technologies for PONs. First, an upstream signal powerequalizer is proposed and designed using a FP-LD in optical line terminal applied to the TDM-PON, and a 20dB dynamic upstream power range from -5 to -25dBm having a 1.7dB maximal power variation is retrieved. The fiber-fault protection is also an important issue for PON. We investigate a simple and cost-effective TDM/WDM PON system with self-protected function. Next, using RSOA-based colorless WDM-PON is also demonstrated. We propose a costeffective CW light source into RSOA for 2.5Gb/s upstream in WDM-PON together with self-healing mechanism against fiber fault. Finally, we investigate a 4Gb/s OFDM-QAM for both upstream and downstream traffic in long-reach WDM/TDM PON system under 100km transmission without dispersion compensation. As a result, we believe that these key access technologies are emerging and useful for the next generation broadband FTTH networks.

  3. Silicon Micromachined Sensor for Broadband Vibration Analysis

    Science.gov (United States)

    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.

  4. Chiral Molecules Revisited by Broadband Microwave Spectroscopy

    Science.gov (United States)

    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. A graphene-based broadband optical modulator

    Science.gov (United States)

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

    2011-06-01

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

  6. Broadband homodecoupled heteronuclear multiple bond correlation spectroscopy.

    Science.gov (United States)

    Sakhaii, Peyman; Haase, Burkhard; Bermel, Wolfgang

    2013-03-01

    A general concept for removing proton-proton scalar J couplings in 2D NMR spectroscopy is proposed. The idea is based on introducing an additional J resolved dimension into the pulse sequence of a conventional 2D experiment to design a pseudo 3D NMR experiment. The practical demonstration is exemplified on the widely used gradient coherence selected heteronuclear long-range correlation spectroscopy (HMBC). We refer to this type of pulse sequence as tilt HMBC experiment. For every (13)C chemical shift evolution increment, a homonuclear J resolved experiment is recorded. The long-range defocusing delay of the HMBC pulse sequence is exploited to implement this building block. The J resolved evolution period is incremented in a way very similar to ACCORDION spectroscopy to accommodate the buildup of heteronuclear long-range antiphase magnetisation as well. After Fourier transformation in all dimensions the spectra are tilted in the J resolved dimension. Finally, a projection along the J resolved dimension is calculated leading to almost disappearance of proton-proton spin multiplicities in the 2D tilt HMBC spectrum. The tilt HMBC experiment combines sensitivity with simple experimental setup and can be recorded with short recycle delays, when combined with Ernst angle excitation. The recorded spectra display singlet proton signals for long-range correlation peaks making an unambiguous signal assignment much easier. In addition to the new experiment a simple processing technique is applied to efficiently suppress the noise originating from forward linear prediction in the indirect evolution dimensions. In case of issues with fast repetition times, probe heating and RF power handling most of the RF pulses can be replaced by broadband, frequency swept pulses operating at much lower power.

  7. The Representation of a Broadband Vector Field

    Institute of Scientific and Technical Information of China (English)

    Qunyan Ren; Jean Pierre Hermand; Shengchun Piao

    2011-01-01

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

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

    Science.gov (United States)

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

    2016-08-01

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

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

    CERN Document Server

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

    2016-01-01

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

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

    CERN Document Server

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

    2015-01-01

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

  11. Perfect and broadband acoustic absorption by critical coupling

    CERN Document Server

    Romero-García, V; Richoux, O; Merkel, A; Tournat, V; Pagneux, V

    2015-01-01

    We experimentally and analytically report broadband and narrowband perfect absorption in two different acoustic waveguide-resonator geometries by the mechanism of critical coupling. In the first geometry the resonator (a Helmholtz resonator) is side-loaded to the waveguide and it has a moderate quality factor. In the second geometry the resonator (a viscoelastic porous plate) is in-line loaded and it contains two resonant modes with low quality factor. The interplay between the energy leakage of the resonant modes into the waveguide and the inherent losses of the system reveals a perfect and a broadband nearly perfect absorption. The results shown in this work can motivate relevant research for the design of broadband perfect absorbers in other domains of wave physics.

  12. Broadband and Resonant Approaches to Axion Dark Matter Detection.

    Science.gov (United States)

    Kahn, Yonatan; Safdi, Benjamin R; Thaler, Jesse

    2016-09-30

    When ultralight axion dark matter encounters a static magnetic field, it sources an effective electric current that follows the magnetic field lines and oscillates at the axion Compton frequency. We propose a new experiment to detect this axion effective current. In the presence of axion dark matter, a large toroidal magnet will act like an oscillating current ring, whose induced magnetic flux can be measured by an external pickup loop inductively coupled to a SQUID magnetometer. We consider both resonant and broadband readout circuits and show that a broadband approach has advantages at small axion masses. We estimate the reach of this design, taking into account the irreducible sources of noise, and demonstrate potential sensitivity to axionlike dark matter with masses in the range of 10^{-14}-10^{-6}  eV. In particular, both the broadband and resonant strategies can probe the QCD axion with a GUT-scale decay constant.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-12-21

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

  14. Broadband and Resonant Approaches to Axion Dark Matter Detection

    Science.gov (United States)

    Kahn, Yonatan; Safdi, Benjamin R.; Thaler, Jesse

    2016-09-01

    When ultralight axion dark matter encounters a static magnetic field, it sources an effective electric current that follows the magnetic field lines and oscillates at the axion Compton frequency. We propose a new experiment to detect this axion effective current. In the presence of axion dark matter, a large toroidal magnet will act like an oscillating current ring, whose induced magnetic flux can be measured by an external pickup loop inductively coupled to a SQUID magnetometer. We consider both resonant and broadband readout circuits and show that a broadband approach has advantages at small axion masses. We estimate the reach of this design, taking into account the irreducible sources of noise, and demonstrate potential sensitivity to axionlike dark matter with masses in the range of 10-14-10-6 e V . In particular, both the broadband and resonant strategies can probe the QCD axion with a GUT-scale decay constant.

  15. Broadband negative refractive index obtained by plasmonic hybridization in metamaterials

    Science.gov (United States)

    Nguyen, Hien T.; Bui, Tung S.; Yan, Sen; Vandenbosch, Guy A. E.; Lievens, Peter; Vu, Lam D.; Janssens, Ewald

    2016-11-01

    We experimentally demonstrate a broadband negative refractive index (NRI) behavior in combined dimer and fishnet dimer metamaterials operating in the GHz frequency range. The observations can be well explained by a hybridization model and are in agreement with numerical modelling results. Hybridization of the magnetic resonances is obtained by reducing the distance between the layers in the dimer structures. A ratio of the double negative refractive index bandwidth to operational frequency of approximately 10% was achieved in the fishnet dimer. The applicable frequency range of the broadband NRI was shown to scale with the size of the structures from the microwave to the far infrared.

  16. Symmetry-Breaking Plasmonic Metasurfaces for Broadband Light Bending

    DEFF Research Database (Denmark)

    Ni, Xingjie; Emani, Naresh K.; Kildishev, Alexander V.;

    2012-01-01

    We experimentally demonstrate unparalleled wave-front control in a broadband, optical wavelength range from 1.0 μm to 1.9 μm, using a thin plasmonic layer (metasurface) consisting of a nanoantenna array that breaks the symmetry along the interface.......We experimentally demonstrate unparalleled wave-front control in a broadband, optical wavelength range from 1.0 μm to 1.9 μm, using a thin plasmonic layer (metasurface) consisting of a nanoantenna array that breaks the symmetry along the interface....

  17. The Quest for Ultimate Broadband High Power Microwaves

    CERN Document Server

    Podgorski, Andrew S

    2014-01-01

    Paper describes High Power Microwave research of combining GW peak power to achieve MV/m and GV/m radiated fields in 1 to 500 GHz band. To achieve such fields multiple independently triggered broadband GW sources, supplying power to multiple spatially distributed broadband radiators/antennas are used. Single TW array is used as an ultimate microwave weapon in 1 to 5 GHz range while multiple TW arrays provide GV/m radiating field at plasma frequencies in 300 GHz range leading to fusion power.

  18. Broadband Coherent Enhancement of Transmission and Absorption in Disordered Media

    CERN Document Server

    Hsu, Chia Wei; Bromberg, Yaron; Stone, A Douglas; Cao, Hui

    2015-01-01

    We study the optimal diffusive transmission and absorption of broadband or polychromatic light in a disordered medium. By introducing matrices describing broadband transmission and reflection, we formulate an extremal eigenvalue problem where the optimal input wavefront is given by the corresponding eigenvector. We show analytically that a single wavefront can exhibit strongly enhanced total transmission or total absorption across a bandwidth that is orders of magnitude broader than the spectral correlation width of the medium, due to long-range correlations in coherent diffusion. We find excellent agreement between the analytic theory and numerical simulations.

  19. Rapid detection of arsenic minerals using portable broadband NQR

    Science.gov (United States)

    Lehmann-Horn, J. A.; Miljak, D. G.; O'Dell, L. A.; Yong, R.; Bastow, T. J.

    2014-10-01

    The remote real-time detection of specific arsenic species would significantly benefit in minerals processing to mitigate the release of arsenic into aquatic environments and aid in selective mining. At present, there are no technologies available to detect arsenic minerals in bulk volumes outside of laboratories. Here we report on the first room-temperature broadband 75As nuclear quadrupole resonance (NQR) detection of common and abundant arsenic ores in the Earth crust using a large sample (0.78 L) volume prototype sensor. Broadband excitation aids in detection of natural minerals with low crystallinity. We briefly discuss how the proposed NQR detector could be employed in mining operations.

  20. Broadband electrical impedance matching for piezoelectric ultrasound transducers.

    Science.gov (United States)

    Huang, Haiying; Paramo, Daniel

    2011-12-01

    This paper presents a systematic method for designing broadband electrical impedance matching networks for piezoelectric ultrasound transducers. The design process involves three steps: 1) determine the equivalent circuit of the unmatched piezoelectric transducer based on its measured admittance; 2) design a set of impedance matching networks using a computerized Smith chart; and 3) establish the simulation model of the matched transducer to evaluate the gain and bandwidth of the impedance matching networks. The effectiveness of the presented approach is demonstrated through the design, implementation, and characterization of impedance matching networks for a broadband acoustic emission sensor. The impedance matching network improved the power of the acquired signal by 9 times.

  1. Midinfrared broadband achromatic astronomical beam combiner for nulling interferometry.

    Science.gov (United States)

    Hsiao, Hsien-kai; Winick, Kim A; Monnier, John D

    2010-12-10

    Integrated optic beam combiners offer many advantages over conventional bulk optic implementations for astronomical imaging. To our knowledge, integrated optic beam combiners have only been demonstrated at operating wavelengths below 4 μm. Operation in the midinfrared wavelength region, however, is highly desirable. In this paper, a theoretical design technique based on three coupled waveguides is developed to achieve fully achromatic, broadband, polarization-insensitive, lossless beam combining. This design may make it possible to achieve the very deep broadband nulls needed for exoplanet searching.

  2. Semiconductor Quantum Dash Broadband Emitters: Modeling and Experiments

    KAUST Repository

    Khan, Mohammed Zahed Mustafa

    2013-10-01

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

  3. A novel structure for a broadband left-handed metamaterial

    Institute of Scientific and Technical Information of China (English)

    Xiong Han; Hong Jing-Song; Jin Da-Lin; Zhang Zhi-Min

    2012-01-01

    A low absorptivity broadband negative refractive index metamaterial with a multi-gap split-ring and metallic cross (MSMC) structure is proposed and investigated numerically and experimentally in the microwave frequency range.The effective media parameters were retrieved from the numerical and experimental results,which clearly show that there exists a very wide frequency band where the permittivity and permeability are negative.The influence of the structure parameters on the magnetic response and the cut-off frequency of the negative permittivity are studied in detail.This metamaterial would have potential application in designing broadband microwave devices.

  4. Broadband high reflectivity in subwavelength-grating slab waveguides

    CERN Document Server

    Cui, Xuan; Zhou, Zhongxiang

    2015-01-01

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

  5. Combless broadband terahertz generation with conventional laser diodes.

    Science.gov (United States)

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

    2011-03-14

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

  6. Implementation of Scientific Computing Applications on the Cell Broadband Engine

    Directory of Open Access Journals (Sweden)

    Guochun Shi

    2009-01-01

    Full Text Available The Cell Broadband Engine architecture is a revolutionary processor architecture well suited for many scientific codes. This paper reports on an effort to implement several traditional high-performance scientific computing applications on the Cell Broadband Engine processor, including molecular dynamics, quantum chromodynamics and quantum chemistry codes. The paper discusses data and code restructuring strategies necessary to adapt the applications to the intrinsic properties of the Cell processor and demonstrates performance improvements achieved on the Cell architecture. It concludes with the lessons learned and provides practical recommendations on optimization techniques that are believed to be most appropriate.

  7. Analysis of broadband aerodynamic noise from VS45

    Energy Technology Data Exchange (ETDEWEB)

    Dundabin, P. [Renewable Energy Systems Ltd., Glasgow, Scotland (United Kingdom)

    1997-12-31

    This paper describes the analysis of acoustic data taken from the VS45 at Kaiser-Wilhelm-Koog. The aim was to investigate the dependence of aerodynamic noise on tip speed and angle of attack. In particular, the dependence of noise in individual third octave bands on these variable is examined. The analysis is divided into 3 sections: data selection, data checks and analysis of broadband nacelle noise; analysis of broadband aerodynamic noise and its sensitivity to tip speed and angle of attack. (LN)

  8. Comparison of VP broadband tiltmeter and VS vertical pendulum tiltmeter

    Directory of Open Access Journals (Sweden)

    Wugang Ma

    2015-05-01

    Full Text Available Vertical pendulum (VP tiltmeter is a kind of earthquake precursor observation equipment, which is used to record the interaction force associated with astronomical tidal tilts caused. Currently, VP broadband tiltmeter and vertical sensor (VS vertical pendulum tiltmeter are primarily used. In this paper, we compare the two different instruments by using four aspects—mechanical structure, circuitry, zeroing, and bandwidth—based on their working principles and applications. We conclude that VP broadband tiltmeter is more superior compared with VS vertical pendulum tiltmeter because of its higher bandwidth and degree of automation.

  9. Broadband Wireline Provider Service: Asymmetric xDSL; BBRI_DSLasym12

    Data.gov (United States)

    University of Rhode Island Geospatial Extension Program — This dataset represents the availability of wireline broadband Internet access in Rhode Island via Asymmetric xDSL technology. Broadband availability is summarized...

  10. Broadband Wireline Provider Service: Optical Carrier - Fiber to the End User; BBRI_fiber12

    Data.gov (United States)

    University of Rhode Island Geospatial Extension Program — This dataset represents the availability of wireline broadband Internet access in Rhode Island via "Optical Carrier - Fiber to the End User" technology. Broadband...

  11. Broadband Wireline Provider Service: Symmetric xDSL; BBRI_DSLsym12

    Data.gov (United States)

    University of Rhode Island Geospatial Extension Program — This dataset represents the availability of wireline broadband Internet access in Rhode Island via Symmetric xDSL technology. Broadband availability is summarized at...

  12. Broadband Wireline Provider Service: Cable Modem - DOCSIS 3.0; BBRI_cableDOCSIS12

    Data.gov (United States)

    University of Rhode Island Geospatial Extension Program — This dataset represents the availability of wireline broadband Internet access in Rhode Island via "Cable Modem - DOCSIS 3.0" technology. Broadband availability is...

  13. 76 FR 23812 - Reliability and Continuity of Communications Networks, Including Broadband Technologies; Effects...

    Science.gov (United States)

    2011-04-28

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

  14. VT Fiber Optic Broadband Availability by Census Block - 12-2012

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201212 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2012. This...

  15. VT Fiber Optic Broadband Availability by Census Block - 12-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201112 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2011. This...

  16. VT Fiber Optic Broadband Availability by Census Block - 06-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201006 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2010. This...

  17. VT Fiber Optic Broadband Availability by Census Block - 12-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201012 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2010. This...

  18. VT Fiber Optic Broadband Availability by Census Block - 06-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201106 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2011. This...

  19. Broadband Wireline Provider Service: Cable Modem - Other; BBRI_cableOther12

    Data.gov (United States)

    University of Rhode Island Geospatial Extension Program — This dataset represents the availability of wireline broadband Internet access in Rhode Island via "Cable Modem - Other" technology. Broadband availability is...

  20. Energy efficient evolution of mobile broadband networks

    Energy Technology Data Exchange (ETDEWEB)

    Micallef, G.

    2013-04-15

    existing macro base station sites together with the deployment of outdoor or indoor small cells (heterogeneous network) provide the best compromise between performance and power consumption. Focusing on one of the case studies, it is noted that the upgrade of both HSPA and LTE network layers results in the power consumption of the network increasing by a factor of 4. When coupled with the growth in capacity introduced by the various upgrades (x50), the efficiency of the network is still greatly improved. Over the evolution period, the stated increase in power consumption does not consider improvement in base station equipment. By considering a number of different equipment versions, the evolution study is further extended to also include the impact of replacing old equipment. Results show that an aggressive replacement strategy and the upgrade of sites to remote radio head can restrain the increase in power consumption of the network to just 17%. In addition to upgrading equipment, mobile network operators can further reduce power consumption by enabling a number of power saving features. These features often exploit redundancies within the network and/or the variation in traffic over a daily period. An example of such feature is sleep mode, which allows for base station sites to be systematically powered down during hours with low network traffic. While dependent on the traffic profile, within an urban area sleep mode can reduce the daily energy consumption of the network by around 20%. In addition to the different variances of sleep mode, the potential savings of other features are also described. Selecting a power efficient network capacity evolution path, replacing old and less efficient equipment, and enabling power saving features, can all considerably reduce the power consumption of future mobile broadband networks. Studies and recommendations presented within this thesis demonstrate that it is realistic for mobile network operators to boost network capacity by a

  1. Community Broadband Networks and the Opportunity for E-Government Services

    DEFF Research Database (Denmark)

    Williams, Idongesit

    2017-01-01

    Community Broadband Networks (CBN) facilitate Broadband connectivity in underserved areas in many countries. The lack of Broadband connectivity is one of the reasons for the slow diffusion of e-government services in many countries.This article explains how CBNs can be enabled by governments...... to facilitate the delivery of e–government services in underserved areas in the developed and developing countries.The Community Based Broadband Mobilization (CBNM) models are used as explanatory tools....

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

    Science.gov (United States)

    Menon, Siddhartha Shankar

    2010-01-01

    Broadband holds a critical position in the progress of economic and social indicators by connecting consumers, businesses and governments. South Korea has consistently been the global leader in broadband deployment since 1999. In the last ten years the Korean government has pursued several strategies for its broadband policy. The purpose of this…

  3. 76 FR 28397 - Acceleration of Broadband Deployment by Improving Policies Regarding Public Rights of Way and...

    Science.gov (United States)

    2011-05-17

    ... COMMISSION 47 CFR Chapter I Acceleration of Broadband Deployment by Improving Policies Regarding Public... broadband deployment through improved policies regarding public rights of way and wireless facilities siting... broadband deployment by encouraging improvements in policies regarding public rights of way and...

  4. Photonic crystal fiber design for broadband directional coupling

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper; Bang, Ole; Bjarklev, Anders Overgaard

    2004-01-01

    A novel design for a broadband directional coupler based on a photonic crystal fiber is investigated numerically. It is shown that suitable index-depressing doping of the core regions in an index-guiding twin-core photonic crystal fiber can stabilize the coupling coefficient between the cores over...

  5. A Broadband Metasurface-Based Terahertz Flat-Lens Array

    KAUST Repository

    Wang, Qiu

    2015-02-12

    A metasurface-based terahertz flat-lens array is proposed, comprising C-shaped split-ring resonators exhibiting locally engineerable phase discontinuities. Possessing a high numerical aperture, the planar lens array is flexible, robust, and shows excellent focusing characteristics in a broadband terahertz frequency. It could be an important step towards the development of planar terahertz focusing devices for practical applications.

  6. Bottle microresonator broadband and low repetition rate frequency comb generator

    CERN Document Server

    Dvoyrin, V

    2016-01-01

    We propose a new type of broadband and low repetition rate frequency comb generator which has the shape of an elongated and nanoscale-shallow optical bottle microresonator created at the surface of an optical fiber. The free spectral range (FSR) of the broadband azimuthal eigenfrequency series of this resonator is the exact multiple of the FSR of the dense and narrowband axial series. The effective radius variation of the microresonator is close to a parabola with a nanoscale height which is greater or equal to lambda/2pi*n0 (here lambda is the characteristic radiation wavelength and n0 is the refractive index of the microresonator material). Overall, the microresonator possesses a broadband, small FSR, and accurately equidistant spectrum convenient for the generation of a broadband and low repetition rate optical frequency comb. It is shown that this comb can be generated by pumping with a cw laser, which radiation frequency matches a single axial eigenfrequency of the microresonator, or, alternatively, by p...

  7. The social surplus of broadband initiatives in compulsory education

    Directory of Open Access Journals (Sweden)

    David Peter Parsons

    2016-10-01

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

  8. Nonlinear Analysis of Renal Autoregulation Under Broadband Forcing Conditions

    DEFF Research Database (Denmark)

    Marmarelis, V Z; Chon, K H; Chen, Y M;

    1994-01-01

    Linear analysis of renal blood flow fluctuations, induced experimentally in rats by broad-band (pseudorandom) arterial blood pressure forcing at various power levels, has been unable to explain fully the dynamics of renal autoregulation at low frequencies. This observation has suggested the possi...

  9. Architectures for ku-band broadband airborne satellite communication antennas

    NARCIS (Netherlands)

    Verpoorte, Jaco; Schippers, Harmen; Jorna, Pieter; Roeloffzen, Chris G.H.; Marpaung, David A.I.; Baggen, Rens; Sanadgol, Bahram

    2010-01-01

    This paper describes different architectures for a broadband antenna for satellite communication on aircraft. The antenna is a steerable (conformal) phased array antenna in Ku-band (receive-only). First the requirements for such a system are addressed. Subsequently a number of potential architecture

  10. Linearization Technologies for Broadband Radio-Over-Fiber Transmission Systems

    Directory of Open Access Journals (Sweden)

    Xiupu Zhang

    2014-11-01

    Full Text Available Linearization technologies that can be used for linearizing RoF transmission are reviewed. Three main linearization methods, i.e. electrical analog linearization, optical linearization, and electrical digital linearization are presented and compared. Analog linearization can be achieved using analog predistortion circuits, and can be used for suppression of odd order nonlinear distortion components, such as third and fifth order. Optical linearization includes mixed-polarization, dual-wavelength, optical channelization and the others, implemented in optical domain, to suppress both even and odd order nonlinear distortion components, such as second and third order. Digital predistortion has been a widely used linearization method for RF power amplifiers. However, digital linearization that requires analog to digital converter is severely limited to hundreds of MHz bandwidth. Instead, analog and optical linearization provide broadband linearization with up to tens of GHz. Therefore, for broadband radio over fiber transmission that can be used for future broadband cloud radio access networks, analog and optical linearization are more appropriate than digital linearization. Generally speaking, both analog and optical linearization are able to improve spur-free dynamic range greater than 10 dB over tens of GHz. In order for current digital linearization to be used for broadband radio over fiber transmission, the reduced linearization complexity and increased linearization bandwidth are required. Moreover, some digital linearization methods in which the complexity can be reduced, such as Hammerstein type, may be more promising and require further investigation.

  11. Coherent broadband light source for parallel optical coherence tomography

    NARCIS (Netherlands)

    Rivier, S.; Laversenne, L.; Bourquin, S.; Salathé, R.P.; Pollnau, M.; Grivas, C.; Shepherd, D.P.; Eason, R.W.; Flury, M.; Philipoussis, I.; Herzig, H.P.

    2004-01-01

    A Ti:sapphire planar waveguide is rib structured by Ar ion milling to provide parallel channel waveguides. By coupling high-power pump light through a microlens array into the waveguides, a novel broadband luminescent parallel emitter is demonstrated as a light source for parallel optical coherence

  12. Broadband and tuned signal recycling with a simple michelson interferometer.

    Science.gov (United States)

    Gray, M B; Stevenson, A J; Bachor, H A; McClelland, D E

    1998-09-01

    We present experimental data on the frequency response of both broadband and tuned signal recycling with a benchtop Michelson interferometer. These data are in excellent agreement with our simple theoretical model. We use in-line modulation to give a control system that provides a high degree of orthogonality between the two servo loops.

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

    NARCIS (Netherlands)

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

    2010-01-01

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

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

    Science.gov (United States)

    Qi, Dong-Xiang; Fan, Ren-Hao; Deng, Yu-Qiang; Peng, Ru-Wen; Wang, Mu; Jiangnan University Collaboration

    In this talk, we present our studies on broadband properties of acoustic waves through metal gratings. We have demonstrated that serrated metal gratings, which introduce gradient coatings, can give rise to broadband transmission enhancement of acoustic waves. Here, we have experimentally and theoretically studied the acoustic transmission properties of metal gratings with or without serrated boundaries. The average transmission is obviously enhanced for serrated metal gratings within a wide frequency range, while the Fabry-Perot resonance is significantly suppressed. An effective medium hypothesis with varying acoustic impedance is proposed to analyze the mechanism, which was verified through comparison with finite-element simulation. The serrated boundary supplies gradient mass distribution and gradient normal acoustic impedance, which could efficiently reduce the boundary reflection. Further, by increasing the region of the serrated boundary, we present a broadband high-transmission grating for wide range of incident angle. Our results may have potential applications to broadband acoustic imaging, acoustic sensing and new acoustic devices. References: [1] Dong-Xiang Qi, Yu-Qiang Deng, Di-Hu Xu, Ren-Hao Fan, Ru-Wen Peng, Ze-Guo Chen, Ming-Hui Lu, X. R. Huang and Mu Wang, Appl. Phys. Lett. 106, 011906 (2015); [2] Dong-Xiang Qi, Ren-Hao Fan, Ru-Wen Peng, Xian-Rong Huang, Ming-Hui Lu, Xu Ni, Qing Hu, and Mu Wang, Applied Physics Letters 101, 061912 (2012).

  15. Broadband seismic by means of dispersed source arrays

    NARCIS (Netherlands)

    Caporal, M.; Blacquiere, G.

    2015-01-01

    Seismic sources deployed during a particular survey are historically chosen to be equal. However, from a physical point of view the constraint of using only identical source units is not required. We suggest to abandon this constraint and to replace, or reinforce, traditional broadband sources with

  16. Broad-band hard X-ray reflectors

    DEFF Research Database (Denmark)

    Joensen, K.D.; Gorenstein, P.; Hoghoj, P.;

    1997-01-01

    Interest in optics for hard X-ray broad-band application is growing. In this paper, we compare the hard X-ray (20-100 keV) reflectivity obtained with an energy-dispersive reflectometer, of a standard commercial gold thin-film with that of a 600 bilayer W/Si X-ray supermirror. The reflectivity of ...

  17. Multicomponent gas analysis using broadband quantum cascade laser spectroscopy

    NARCIS (Netherlands)

    Reyes Reyes, A.; Hou, Z.; Van Mastrigt, E.; Horsten, R.C.; De Jongste, J.C.; Pijnenburg, M.W.; Urbach, H.P.; Bhattacharya, N.

    2014-01-01

    We present a broadband quantum cascade laser-based spectroscopic system covering the region between 850 and 1250 cm−1. Its robust multipass cavity ensures a constant interaction length over the entire spectral region. The device enables the detection and identification of numerous molecules present

  18. Distributed Shared Memory for the Cell Broadband Engine (DSMCBE)

    DEFF Research Database (Denmark)

    Larsen, Morten Nørgaard; Skovhede, Kenneth; Vinter, Brian

    2009-01-01

    in and out of non-coherent local storage blocks for each special processor element. In this paper we present a software library, namely the Distributed Shared Memory for the Cell Broadband Engine (DSMCBE). By using techniques known from distributed shared memory DSMCBE allows programmers to program the CELL...

  19. Narrowband to broadband conversion of Landsat TM glacier albedos

    NARCIS (Netherlands)

    Oerlemans, J.; Knap, W.H.; Reijmer, C.

    1999-01-01

    In this paper we present an empirical relationship between the broadband glacier albedo (alpha) and the narrowband glacier albedos in Landsat TM bands 2 and 4 (alpha2 and alpha4, respectively). The relationship was established on the basis of multiple linear regression analysis of 112 ground-based s

  20. 76 FR 13769 - Rural Broadband Access Loans and Loan Guarantees

    Science.gov (United States)

    2011-03-14

    ... access too high, or limit potential demand, thus depressing the profitability of providing service... speed. Broadband loan. Build-out. Competitive analysis. Cost share. Customer premise equipment (CPE... in a notice in the Federal Register, that an applicant must deliver to the customer in order for...

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

    Science.gov (United States)

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

    2010-01-01

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

  2. Kalman filtering and Standard Quantum Limits for broadband measurement

    CERN Document Server

    Mabuchi, H

    1998-01-01

    I utilize the Caves-Milburn model for continuous position measurements to formulate a broadband version of the Standard Quantum Limit (SQL) for monitoring the position of a free mass, and illustrate the use of Kalman filtering to recover the SQL for estimating a weak classical force that acts on a quantum-mechanical test particle under continuous observation.

  3. Broadband microwave photonic phase shifter based on polarisation rotation

    DEFF Research Database (Denmark)

    Xue, Weiqi; Öhman, Filip; Blaaberg, Søren;

    2008-01-01

    A broadband microwave photonic phase shifter is presented based on the polarisation properties of a Mach-Zehnder intensity modulator and nonlinear polarisation rotation in a semiconductor optical amplifier. The system can realise about 150deg phase shift in the frequency range from 50 MHz to 19 GHz....

  4. 78 FR 25787 - Community Connect Broadband Grant Program

    Science.gov (United States)

    2013-05-03

    ... announces the opening of the window for submitting applications and will be set at the level that is needed... the opening of an application window) may set the requirements for fixed and mobile broadband service... providers and providers of satellite services) that is participating in the delivery of services and...

  5. Rapidly converging multichannel controllers for broadband noise and vibrations

    NARCIS (Netherlands)

    Berkhoff, A.P.

    2010-01-01

    Applications are given of a preconditioned adaptive algorithm for broadband multichannel active noise control. Based on state-space descriptions of the relevant transfer functions, the algorithm uses the inverse of the minimum-phase part of the secondary path in order to improve the speed of converg

  6. Biobased Nanoparticles for Broadband UV Protection with Photostabilized UV Filters

    NARCIS (Netherlands)

    Hayden, D.R.; Imhof, A.; Velikov, K. P.

    2016-01-01

    Sunscreens rely on multiple compounds to provide effective and safe protection against UV radiation. UV filters in sunscreens, in particular, provide broadband UV protection but are heavily linked to adverse health effects due to the generation of carcinogenic skin-damaging reactive oxygen species (

  7. China Netcom: Stressing on Broadband and Building an Innovative Enterprise

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    China Network Communications Group Corporation (CNC) proposed and reaffirmed for many times the strategic objective of transferring to a broadband communication and multimedia service provider since the beginning of this year. CNC, insisting on self-innovation, is going to forge itself into a domestically high-class and internationally influential innovative company within five years.

  8. 47 CFR 27.1305 - Shared wireless broadband network.

    Science.gov (United States)

    2010-10-01

    ... broadband technology platform that provides mobile voice, video, and data capability that is seamlessly... includes current and evolving state-of-the-art technologies reasonably made available in the commercial...) Sufficient capacity to meet the needs of public safety. (e) Security and encryption consistent with...

  9. Broad-band spectrophotometry of HAT-P-32 b

    DEFF Research Database (Denmark)

    Mallonn, M.; Bernt, I.; Herrero, E.

    2016-01-01

    Multicolour broad-band transit observations offer the opportunity to characterize 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 previou...

  10. A comparison of vernier acuity for narrowband and broadband stimuli.

    Science.gov (United States)

    Barrett, Brendan T; Whitaker, David

    2004-01-01

    This study investigates the influence of contrast and exposure duration on vernier acuity thresholds for abutting and separated narrowband stimuli, and asks whether these data can predict broadband vernier performance. Vernier thresholds were determined for sinusoidal grating stimuli at two spatial frequencies (1 and 8 c/deg) across a range of contrasts (0.05-0.8) and exposure durations (35-2100 ms). Performance was assessed for the abutting configuration, and when a gap equivalent to 0.5 to 1.5 times the spatial period of the grating was introduced between the upper and lower halves of the grating. Vernier thresholds were also determined for a square-wave stimulus as a function of contrast (0.06 to 0.78). Exposure duration was fixed at 2100 ms. In addition, thresholds were determined at the appropriate contrast levels for the fundamental frequency (1.8 c/deg) of the square-wave, and for a number of the harmonics (3F, 5F, 7F, 9F). Our results provide support for filter models of vernier acuity by showing that vernier performance for abutting and closely-separated broadband stimuli represents the envelope of vernier sensitivity of those spatial frequency mechanisms that are activated by the broadband stimulus. In the case of high frequency grating stimuli presented for long exposure durations, vernier performance can be invariant across much of the contrast range. Despite this, however, contrast independence is not exhibited for abutting broadband stimuli because, within the broadband stimuli, the contrast of the higher harmonic components never reaches a level to reveal this plateau.

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

    Energy Technology Data Exchange (ETDEWEB)

    Reda, I.

    2015-03-01

    Solar and atmospheric science radiometers, e.g. pyranometers, pyrheliometers, and photovoltaic cells are calibrated with traceability to a consensus reference, which is maintained by Absolute Cavity Radiometers (ACRs). The ACR is an open cavity with no window, developed to measure extended broadband direct solar irradiance beyond the ultraviolet and infrared bands below and above 0.2 um and 50 um, respectively. On the other hand, pyranometers and pyrheliometers are developed to measure broadband shortwave irradiance from approximately 0.3 um to 3 um, while the present photovoltaic cells are limited to approximately 0.3 um to 1 um. The broadband mismatch of ACR versus such radiometers causes discrepancy in radiometers' calibration methods that has not been discussed or addressed in the solar and atmospheric science literature. Pyrgeometers are also used for solar and atmospheric science applications and are calibrated with traceability to consensus reference, yet are calibrated during nighttime only, because no consensus reference has yet been established for the daytime longwave irradiance. This poster shows a method to measure the broadband IR irradiance in the direct solar beam from 3 um to 50 um, as a first step that might be used to help develop calibration methods to address the mismatch between broadband ACR and shortwave radiometers, and the lack of a daytime reference for pyrgeometers. The irradiance was measured from sunrise to sunset for 5 days when the sun disk was cloudless; the irradiance varied from approximately 1 Wm-2 to 16 Wm-2 for solar zenith angle from 80 degrees to 16 degrees respectively; estimated uncertainty is 1.5 Wm-2.

  12. Measuring Broadband IR Irradiance in the Direct Solar Beam (Poster)

    Energy Technology Data Exchange (ETDEWEB)

    Reda, I.; Konings, J.; Xie, Y.; Dooraghi, M.; Sengupta, M.

    2015-03-01

    Solar and atmospheric science radiometers, e.g. pyranometers, pyrheliometers, and photovoltaic cells are calibrated with traceability to a consensus reference, which is maintained by Absolute Cavity Radiometers (ACRs). The ACR is an open cavity with no window, developed to measure extended broadband direct solar irradiance beyond the ultraviolet and infrared bands below and above 0.2 micrometers and 50 micrometers, respectively. On the other hand, pyranometers and pyrheliometers are developed to measure broadband shortwave irradiance from approximately 0.3 micrometers to 3 micrcometers, while the present photovoltaic cells are limited to approximately 0.3 micrometers to 1 micrometers. The broadband mismatch of ACR versus such radiometers causes discrepancy in radiometers' calibration methods that has not been discussed or addressed in the solar and atmospheric science literature. Pyrgeometers are also used for solar and atmospheric science applications and calibrated with traceability to consensus reference, yet calibrated during nighttime only, because no consensus reference has yet been established for the daytime longwave irradiance. This poster shows a method to measure the broadband IR irradiance in the direct solar beam from 3 micrometers to 50 micrometers, as first step that might be used to help develop calibration methods to address the mismatch between broadband ACR and shortwave radiometers, and the lack of a daytime reference for pyrgeometers. The irradiance was measured from sunrise to sunset for 5 days when the sun disk was cloudless; the irradiance varied from approximately 1 Wm-2 to 16 Wm-2 for solar zenith angle from 80 degres to 16 degrees respectively; estimated uncertainty is 1.5 Wm-2.

  13. Energy efficient evolution of mobile broadband networks

    Energy Technology Data Exchange (ETDEWEB)

    Micallef, G.

    2013-04-15

    existing macro base station sites together with the deployment of outdoor or indoor small cells (heterogeneous network) provide the best compromise between performance and power consumption. Focusing on one of the case studies, it is noted that the upgrade of both HSPA and LTE network layers results in the power consumption of the network increasing by a factor of 4. When coupled with the growth in capacity introduced by the various upgrades (x50), the efficiency of the network is still greatly improved. Over the evolution period, the stated increase in power consumption does not consider improvement in base station equipment. By considering a number of different equipment versions, the evolution study is further extended to also include the impact of replacing old equipment. Results show that an aggressive replacement strategy and the upgrade of sites to remote radio head can restrain the increase in power consumption of the network to just 17%. In addition to upgrading equipment, mobile network operators can further reduce power consumption by enabling a number of power saving features. These features often exploit redundancies within the network and/or the variation in traffic over a daily period. An example of such feature is sleep mode, which allows for base station sites to be systematically powered down during hours with low network traffic. While dependent on the traffic profile, within an urban area sleep mode can reduce the daily energy consumption of the network by around 20%. In addition to the different variances of sleep mode, the potential savings of other features are also described. Selecting a power efficient network capacity evolution path, replacing old and less efficient equipment, and enabling power saving features, can all considerably reduce the power consumption of future mobile broadband networks. Studies and recommendations presented within this thesis demonstrate that it is realistic for mobile network operators to boost network capacity by a

  14. Performing broadband optical transmission links by appropriate spectral combination of broadband SOA gain, Raman amplification and transmission fiber losses

    Science.gov (United States)

    Motaweh, T.; Sharaiha, A.; Ghisa, L.; Morel, P.; Guégan, M.; Brenot, R.; Verdier, A.

    2017-02-01

    We present the principle of a broadband optical transmission link based on the appropriate combination of the spectral profiles of broadband SOA gain, Raman amplification and transmission fiber losses. We show that, thanks to this principle, a bandwidth as wide as 89 nm (defined at -1 dB) over 75.5 km can be obtained. This bandwidth remains better than 80 nm over a wide range of optical input powers and broadband SOA bias currents, by optimizing the Raman pump. We also show theoretically that the bandwidth of our link is nearly constant for a fiber length from 25 to 100 km optimizing the SOA current. Our broadband transmission link, extended by 24.5 km of fiber, is then validated by achieving the transmission of five CWDM channels modulated at 10 Gbit/s. All five channels were transmitted over 100 km with a minimum received power sensibility of about -15.5 dBm for a reference BER of 10-3.

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

    Science.gov (United States)

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

    2016-08-01

    In this paper, one kind of helix-like chiral metamaterial which can be realized by multiple conventional lithography or electron beam lithographic techniques is proposed to have a broadband bianisotropic optical response analogous to helical metamaterials. On the basis of twisted metamaterials, via tailoring the relative orientation within the lattice, the anisotropy of arcs is converted into magneto-electric coupling of closely spaced arc pairs, which leads to a broad bianisotropic optical response. By connecting the adjacent upper and lower arcs, the coupling of metasurface pairs is transformed into the coupling of the three-dimensional inclusions, and provides a much broader and higher bianisotropic optical response. For only a four-layer helix-like metamaterial, the maximum extinction ratio can reach 19.7. The operation band is in the wavelength range of 4.69 μm to 8.98 μm with an average extinction ratio of 6.9. And the transmittance for selective polarization is above 0.8 in the entire operation band. Such a structure is a promising candidate for integratable and scalable broadband circular polarizers, especially it has great potential to act as a broadband circular micropolarizer in the field of the full-Stokes division of focal plane polarimeters.In this paper, one kind of helix-like chiral metamaterial which can be realized by multiple conventional lithography or electron beam lithographic techniques is proposed to have a broadband bianisotropic optical response analogous to helical metamaterials. On the basis of twisted metamaterials, via tailoring the relative orientation within the lattice, the anisotropy of arcs is converted into magneto-electric coupling of closely spaced arc pairs, which leads to a broad bianisotropic optical response. By connecting the adjacent upper and lower arcs, the coupling of metasurface pairs is transformed into the coupling of the three-dimensional inclusions, and provides a much broader and higher bianisotropic optical

  16. Superluminal propagation and broadband omnidirectional antireflection in optical reflectionless potentials

    CERN Document Server

    Thekkekara, L V; Kasture, Sachin; Mulay, Gajendra; Gupta, S Dutta

    2013-01-01

    Reflectionless potentials (RPs) represent a class of potentials that offer total transmission in the context of one dimensional scattering. Optical realization of RPs in stratified medium can exhibit broadband omnidirectional antireflection property. In addition to the antireflection property, RPs are also expected to demonstrate negative delay. We designed refractive index profiles conforming to RPs and realize them in stratified media consisting of Al2O3 and TiO2 heterolayers. In these structures we observed < 1% reflection over the broad wavelength range of 350 nm to 2500 nm for angles of incidence 0 - 50 degrees. The observed reflection and transmission response of RPs are polarization independent. A negative delay of about 31 fsec with discernible pulse narrowing was observed in passage through two RPs. These RPs can be interesting for optical instrumentation as broadband, omni-directional antireflection coatings as well as in pulse control and transmission applications like delay lines.

  17. Graphene induced tunable and polarization-insensitive broadband metamaterial absorber

    Science.gov (United States)

    Zhang, Yuping; Li, Yue; Cao, Yanyan; Liu, Yuanzhong; Zhang, Huiyun

    2017-01-01

    We design a tunable and broadband metamaterial absorber in the mid-infrared region based on graphene. The unit cell of the proposed metamaterial absorber consists of circular gold patches, which coupled with a graphene layer, and are separated by a dielectric spacer from the gold film on the bottom. The absorption bandwidth is effectively extended by patterning multi-circular gold patches of different dimension elements with appropriate geometrical parameters in a co-plane. The metamaterial absorber achieves its frequency tunable characteristics via changing the applied voltage or chemical doping to manipulate graphene's Fermi energy. We analyzed the surface current distributions and the distributions of the z-component electric field for understanding the absorption mechanism. Moreover, the design principle here could be regarded as a template to extend bandwidth by introducing more circular patches into each unit cell. Our design has potential applications in various fields of stealth technology, photovoltaic devices, sensors, and broadband communication.

  18. Broadband detuned Sagnac interferometer for future generation gravitational wave astronomy

    CERN Document Server

    Voronchev, N V; Danilishin, S L

    2015-01-01

    Broadband suppression of quantum noise below the Standard Quantum Limit (SQL) becomes a top-priority problem for the future generation of large-scale terrestrial detectors of gravitational waves, as the interferometers of the Advanced LIGO project, predesigned to be quantum-noise-limited in the almost entire detection band, are phased in. To this end, among various proposed methods of quantum noise suppression or signal amplification, the most elaborate approach implies a so-called *xylophone* configuration of two Michelson interferometers, each optimised for its own frequency band, with a combined broadband sensitivity well below the SQL. Albeit ingenious, it is a rather costly solution. We demonstrate that changing the optical scheme to a Sagnac interferometer with weak detuned signal recycling and frequency dependent input squeezing can do almost as good a job, as the xylophone for significantly lower spend. We also show that the Sagnac interferometer is more robust to optical loss in filter cavity, used f...

  19. A Performance Study of Wireless Broadband Access (WiMAX

    Directory of Open Access Journals (Sweden)

    Maan A. S. Al-Adwany

    2011-12-01

    Full Text Available WiMAX (worldwide interoperability for microwave access is one of the wireless broadband access technologies which supplies broadband services to clients, but it surpasses other technologies by its coverage area, where one base station can cover a small city. In this paper, WiMAX technology is studied by exploring its basic concepts, applications, and advantages / disadvantages. Also a MATLAB simulator is used to verify the operation of the WiMAX system under various channel impairments and for variety of modulation schemes. From the simulation results, we found that WiMAX system works well in both AWGN and multipath fading channels, but under certain constraints that are addressed in this paper.

  20. Broadband laser polarization control with aligned carbon nanotubes

    CERN Document Server

    Yang, He; Lia, Diao; Chen, Ya; Mattila, Marco; Tian, Ying; Yong, Zhenzhong; Yang, Changxi; Tittonen, Ilkka; Ren, Zhaoyu; Bai, Jingtao; Li, Qingwen; Kauppinen, Esko I; Lipsanen, Harri; Sun, Zhipei

    2015-01-01

    We introduce a simple approach to fabricate aligned carbon nanotube (ACNT) device for broadband polarization control in fiber laser systems. The ACNT device was fabricated by pulling from as-fabricated vertically-aligned carbon nanotube arrays. Their anisotropic property is confirmed with optical and scanning electron microscopy, and with polarized Raman and absorption spectroscopy. The device was then integrated into fiber laser systems (at two technologically important wavelengths of 1 and 1.5 um) for polarization control. We obtained a linearly-polarized light output with the maximum extinction ratio of ~12 dB. The output polarization direction could be fully controlled by the ACNT alignment direction in both lasers. To the best of our knowledge, this is the first time that ACNT device is applied to polarization control in laser systems. Our results exhibit that the ACNT device is a simple, low-cost, and broadband polarizer to control laser polarization dynamics, for various photonic applications (such as ...

  1. An ultra-broadband low-frequency magnetic resonance system

    Science.gov (United States)

    Mandal, S.; Utsuzawa, S.; Cory, D. G.; Hürlimann, M.; Poitzsch, M.; Song, Y.-Q.

    2014-05-01

    MR probes commonly employ resonant circuits for efficient RF transmission and low-noise reception. These circuits are narrow-band analog devices that are inflexible for broadband and multi-frequency operation at low Larmor frequencies. We have addressed this issue by developing an ultra-broadband MR probe that operates in the 0.1-3 MHz frequency range without using conventional resonant circuits for either transmission or reception. This “non-resonant” approach significantly simplifies the probe circuit and allows robust operation without probe tuning while retaining efficient power transmission and low-noise reception. We also demonstrate the utility of the technique through a variety of NMR and NQR experiments in this frequency range.

  2. Research on Raman Crosstalk in Broadband Wavelength Division Multiplexed Systems

    Institute of Scientific and Technical Information of China (English)

    XUE Fei; QIU Kun

    2004-01-01

    After a theoretical model is put forward on the base of accurate description of the Raman gain profile and the physical quantity,maximum Raman crosstalk(MRC),which quantificationally depicts the intensity of Raman crosstalk is defined.The influences of launch power,fiber effective core area,fiber nonlinear index,fiber length,channel number and channel interval on MRC are deduced.The result indicates that compared with low speed and narrowband optical fiber communication system,serious Raman crosstalk lies in high speed and broadband system,which impacts the performance of the system badly.The result is useful for forecasting Raman crosstalk in broadband and high speed optical fiber communication system.

  3. Broadband and chiral binary dielectric meta-holograms

    Science.gov (United States)

    Khorasaninejad, Mohammadreza; Ambrosio, Antonio; Kanhaiya, Pritpal; Capasso, Federico

    2016-01-01

    Subwavelength structured surfaces, known as meta-surfaces, hold promise for future compact and optically thin devices with versatile functionalities. By revisiting the concept of detour phase, we demonstrate high-efficiency holograms with broadband and chiral imaging functionalities. In our devices, the apertures of binary holograms are replaced by subwavelength structured microgratings. We achieve broadband operation from the visible to the near infrared and efficiency as high as 75% in the 1.0 to 1.4 μm range by compensating for the inherent dispersion of the detour phase with that of the subwavelength structure. In addition, we demonstrate chiral holograms that project different images depending on the handedness of the reference beam by incorporating a geometric phase. Our devices’ compactness, lightness, and ability to produce images even at large angles have significant potential for important emerging applications such as wearable optics. PMID:27386518

  4. Photonic crystals for broadband, omnidirectional self-collimation

    Science.gov (United States)

    Chuang, Y.-C.; Suleski, T. J.

    2011-03-01

    In this paper, multiple photonic crystal (PC) structures are proposed to improve three-dimensional (3D) self-collimation performance, including two 3D PCs (tetragonal lattice structures and a complex hexagonal lattice structure) and two two-dimensional (2D) PCs (triangular lattice structures and kagome lattice structures) with out-of-plane orientation. Different design strategies are investigated and compared in terms of the resulting self-collimation performance. Several desired 3D properties are numerically realized for the first time, including broadband 3D self-collimation, omnidirectional beam confinement and broadband omnidirectional self-collimation. These developments can enable future self-collimation applications, such as multiplexers, PC core fibers and solar light collection.

  5. Broadband solar absorption enhancement via periodic nanostructuring of electrodes.

    KAUST Repository

    Adachi, Michael M

    2013-10-14

    Solution processed colloidal quantum dot (CQD) solar cells have great potential for large area low-cost photovoltaics. However, light utilization remains low mainly due to the tradeoff between small carrier transport lengths and longer infrared photon absorption lengths. Here, we demonstrate a bottom-illuminated periodic nanostructured CQD solar cell that enhances broadband absorption without compromising charge extraction efficiency of the device. We use finite difference time domain (FDTD) simulations to study the nanostructure for implementation in a realistic device and then build proof-of-concept nanostructured solar cells, which exhibit a broadband absorption enhancement over the wavelength range of λ = 600 to 1,100 nm, leading to a 31% improvement in overall short-circuit current density compared to a planar device containing an approximately equal volume of active material. Remarkably, the improved current density is achieved using a light-absorber volume less than half that typically used in the best planar devices.

  6. Broadband terahertz metamaterial absorber based on sectional asymmetric structures

    Science.gov (United States)

    Gong, Cheng; Zhan, Mingzhou; Yang, Jing; Wang, Zhigang; Liu, Haitao; Zhao, Yuejin; Liu, Weiwei

    2016-01-01

    We suggest and demonstrate the concept and design of sectional asymmetric structures which can manipulate the metamaterial absorber’s working bandwidth with maintaining the other inherent advantages. As an example, a broadband terahertz perfect absorber is designed to confirm its effectiveness. The absorber’s each cell integrates four sectional asymmetric rings, and the entire structure composed of Au and Si3N4 is only 1.9 μm thick. The simulation results show the bandwidth with absorptivity being larger than 90% is extended by about 2.8 times comparing with the conventional square ring absorber. The composable small cell, ultra-thin, and broadband absorption with polarization and incident angle insensitivity will make the absorber suitable for the applications of focal plane array terahertz imaging. PMID:27571941

  7. Broadband infrared absorption enhancement by electroless-deposited silver nanoparticles

    DEFF Research Database (Denmark)

    Gritti, Claudia; Raza, Søren; Kadkhodazadeh, Shima

    2017-01-01

    Decorating semiconductor surfaces with plasmonic nanoparticles (NPs) is considered a viable solution for enhancing the absorptive properties of photovoltaic and photodetecting devices. We propose to deposit silver NPs on top of a semiconductor wafer by a cheap and fast electroless plating technique....... Optical characterization confirms that the random array of electroless-deposited NPs improves absorption by up to 20% in a broadband of nearinfrared frequencies from the bandgap edge to 2000 nm. Due to the small filling fraction of particles, the reflection in the visible range is practically unchanged......, which points to the possible applications of such deposition method for harvesting photons in nanophotonics and photovoltaics. The broadband absorption is a consequence of the resonant behavior of particles with different shapes and sizes, which strongly localize the incident light at the interface...

  8. A Broadband Approach to Axion Dark Matter Detection

    CERN Document Server

    Kahn, Yonatan; Thaler, Jesse

    2016-01-01

    When ultralight axion dark matter encounters a static magnetic field, it sources an effective electric current that follows the magnetic field lines and oscillates at the axion Compton frequency. We propose a new experiment to detect this axion effective current. In the presence of axion dark matter, a large toroidal magnet will act like an oscillating current ring, whose induced magnetic flux can be measured by an external pickup loop inductively coupled to a SQUID magnetometer. We consider both resonant and broadband readout circuits and show that a broadband approach has advantages at small axion masses. We estimate the reach of this design, taking into account the irreducible sources of noise, and demonstrate potential sensitivity to axion dark matter with masses in the range of 10^{-13} eV to 10^{-6} eV, particularly the QCD axion with a GUT-scale decay constant.

  9. Broadband electrostatic acoustic transducer for ultrasonic measurements in liquids.

    Science.gov (United States)

    Cantrell, J H; Heyman, J S; Yost, W T; Torbett, M A; Breazeale, M A

    1979-01-01

    A broadband capacitive electrostatic acoustic transducer (ESAT) has been developed for use in a liquid environment at megahertz frequencies. The ESAT basically consists of a thin conductive membrane stretched over a metallic housing. The membrane functions as the ground plate of a parallel plate capacitor, the other plate being a dc biased electrode recessed approximately 10 mum from the electrically grounded membrane. An ultrasonic wave incident on the membrane varies the membrane-electrode gap spacing and generates an electrical signal proportional to the wave amplitude. The entire assembly is sealed for immersion in a liquid environment. Calibration of the ESAT with incident ultrasonic waves of constant displacement amplitude from 1 to 15 MHz reveals a decrease in signal response with increasing frequency independent of membrane tension. The use of the ESAT as a broadband ultrasonic transducer in liquids with a predictable frequency response is promising.

  10. Radiative cooling and broadband phenomenon in low-frequency waves

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In this paper, we analyze the effects of radiative cooling on the pure baroclinic low-frequency waves under the approximation of equatorial -plane and semi-geostrophic condition. The results show that radiative cooling does not, exclusively, provide the damping effects on the development of low-frequency waves. Under the delicate radiative-convective equilibrium, radiative effects will alter the phase speed and wave period, and bring about the broadband of phase velocity and wave period by adjusting the vertical profiles of diabatic heating. when the intensity of diabatic heating is moderate and appropriate, it is conductive to the development and sustaining of the low-frequency waves and their broadband phenomena, not the larger, the better. The radiative cooling cannot be neglected in order to reach the moderate and appropriate intensity of diabatic heating.

  11. Broadband terahertz generation and detection at 10 nm scale.

    Science.gov (United States)

    Ma, Yanjun; Huang, Mengchen; Ryu, Sangwoo; Bark, Chung Wung; Eom, Chang-Beom; Irvin, Patrick; Levy, Jeremy

    2013-06-12

    Terahertz (0.1-30 THz) radiation reveals a wealth of information that is relevant for material, biological, and medical sciences with applications that span chemical sensing, high-speed electronics, and coherent control of semiconductor quantum bits. To date, there have been no methods capable of controlling terahertz (THz) radiation at molecular scales. Here we report both generation and detection of broadband terahertz field from 10 nm scale oxide nanojunctions. Frequency components of ultrafast optical radiation are mixed at these nanojunctions, producing broadband THz emission. These same devices detect THz electric fields with comparable spatial resolution. This unprecedented control, on a scale of 4 orders of magnitude smaller than the diffraction limit, creates a pathway toward THz-bandwidth spectroscopy and control of individual nanoparticles and molecules.

  12. An improved outdoor calibration procedure for broadband ultraviolet radiometers.

    Science.gov (United States)

    Cancillo, M L; Serrano, A; Antón, M; García, J A; Vilaplana, J M; de la Morena, B

    2005-01-01

    This article aims at improving the broadband ultraviolet radiometer's calibration methodology. For this goal, three broadband radiometers are calibrated against a spectrophotometer of reference. Three different one-step calibration models are tested: ratio, first order and second order. The latter is proposed in order to adequately reproduce the high dependence on the solar zenith angle shown by the other two models and, therefore, to improve the calibration performance at high solar elevations. The proposed new second-order model requires no additional information and, thus, keeps the operational character of the one-step methodology. The models are compared in terms of their root mean square error and the most qualified is subsequently validated by comparing its predictions with the spectrophotometer measurements within an independent validation data subset. Results show that the best calibration is achieved by the second-order model, with a mean bias error and mean absolute bias error lower than 2.2 and 6.7%, respectively.

  13. Broadband second harmonic generation in whispering gallery mode resonators

    CERN Document Server

    Lin, Guoping; Strekalov, Dmitry V; Yu, Nan

    2013-01-01

    Optical frequency conversion processes in nonlinear materials are limited in wavelength by the accessible phase matching and the required high pump powers. In this letter, we report a novel broadband phase matching (PM) technique in high quality factor (Q) whispering gallery mode (WGM) resonators made of birefringent crystalline materials. This technique relies on two interacting WGMs, one with constant and the other with spatially oscillating phase velocity. Thus, phase matching occurs cyclically. The technique can be implemented with a WGM resonator with its disk plane parallel to the optic axis of the crystal. With a single beta barium borate (BBO) resonator in that configuration, we experimentally demonstrated efficient second harmonic generation (SHG) to harmonic wavelengths from 780 nm in the near infrared to 317 nm in the ultraviolet (UV). The observed SHG conversion efficiency is as high as 4.6% (mW)-1. This broadband PM technique opens a new way for nonlinear optics applications in WGM resonators. Th...

  14. Broadband Brillouin Scatter from CO2-Laser-Target Interactions

    Science.gov (United States)

    Mitchel, G. R.; Grek, B.; Johnston, T. W.; Pépin, H.; Church, P.; Lavigne, P.; Martin, F.; Décoste, R.

    1982-05-01

    Light scattered near the incident wavelength from CO2 laser-solid target interactions in oblique incidence shows the spectral signature of Brillouin scattering both in the backward and in the near specular directions. This instability is apparently seeded by broadband scatter from the critical density surface and then amplified in the underdense plasma. 60% of the incident light is scattered, and the Brillouin contribution to total scatter may be large if the source is also large.

  15. Broad-Band Molecular Polarization in White Dwarfs

    Science.gov (United States)

    Berdyugina, S. V.; Berdyugin, A. V.; Piirola, V.; Shapiro, A.

    2007-09-01

    We present novel calculations of broad-band polarization due to the molecular Paschen--Back effect in a strong magnetic field. Based on that, we analyze new spectropolarimetric observations of the cool magnetic helium-rich white dwarf G 99-37 which shows strongly polarized molecular bands in its spectrum. Combining the polarimetric observations with our model calculations for the CH bands at 4300 Å, we deduce a magnetic field of 8 MG on this unique magnetic white dwarf.

  16. Broadband Cooperative Spectrum Sensing Based on Distributed Modulated Wideband Converter

    Directory of Open Access Journals (Sweden)

    Ziyong Xu

    2016-09-01

    Full Text Available The modulated wideband converter (MWC is a kind of sub-Nyquist sampling system which is developed from compressed sensing theory. It accomplishes highly accurate broadband sparse signal recovery by multichannel sub-Nyquist sampling sequences. However, when the number of sparse sub-bands becomes large, the amount of sampling channels increases proportionally. Besides, it is very hard to adjust the number of sampling channels when the sparsity changes, because its undersampling board is designed by a given sparsity. Such hardware cost and inconvenience are unacceptable in practical applications. This paper proposes a distributed modulated wideband converter (DMWC scheme innovatively, which regards one sensor node as one sampling channel and combines MWC technology with a broadband cooperative spectrum sensing network perfectly. Being different from the MWC scheme, DMWC takes phase shift and transmission loss into account in the input terminal, which are unavoidable in practical application. Our scheme is not only able to recover the support of broadband sparse signals quickly and accurately, but also reduces the hardware cost of the single node drastically. Theoretical analysis and numerical simulations show that phase shift has no influence on the recovery of frequency support, but transmission loss degrades the recovery performance to a different extent. Nevertheless, we can increase the amount of cooperative nodes and select satisfactory nodes by a different transmission distance to improve the recovery performance. Furthermore, we can adjust the amount of cooperative nodes flexibly when the sparsity changes. It indicates DMWC is extremely effective in the broadband cooperative spectrum sensing network.

  17. Spectrum Policy in the Age of Broadband: Issues for Congress

    Science.gov (United States)

    2010-01-29

    homes or convenient public locations, including airports and café environments such as Starbucks . In 2008, there were over 7,000 Starbucks locations...of by a license-holder. 135 “ Starbucks to Expand Technology Relationship with AT&T,” Starbucks Corporation Press Room, February 11, 2008, http...technologies and to formulate new investment strategies . The possibility of allocating additional spectrum for mobile broadband was among the

  18. Toward broadband electroacoustic resonators through optimized feedback control strategies

    OpenAIRE

    Boulandet, R.; Lissek, H.

    2014-01-01

    This paper presents a methodology for the design of broadband electroacoustic resonators for low-frequency room equalization. An electroacoustic resonator denotes a loudspeaker used as a membrane resonator, the acoustic impedance of which can be modified through proportional feedback control, to match a target impedance. However, such impedance matching only occurs over a limited bandwidth around resonance, which can limit its use for the low-frequency equalization of rooms, requiring an effe...

  19. Monolithic Microwave Integrated Circuits (MMIC) Broadband Power Amplifiers (Part 2)

    Science.gov (United States)

    2013-07-01

    2 Figure 2. A 2-GHz load-pull simulation of output power (Pcomp-6 x 65 µm PHEMT). ..............2 Figure 3. A 2-GHz load-pull simulation of PAE (6...5. MMIC 1–5 GHz output power and PAE performance simulation (1, 2, 3, and 4 GHz...load-pull simulation of PAE (6 x 50 µm PHEMT). .......................................7 Figure 9. MMIC 10–19 GHz broadband power amplifier linear

  20. Patterning of graphite nanocones for broadband solar spectrum absorption

    Directory of Open Access Journals (Sweden)

    Yaoran Sun

    2015-06-01

    Full Text Available We experimentally demonstrate a broadband vis-NIR absorber consisting of 300-400 nm nanocone structures on highly oriented pyrolytic graphite. The nanocone structures are fabricated through simple nanoparticle lithography process and analyzed with three-dimensional finite-difference time-domain methods. The measured absorption reaches an average level of above 95% over almost the entire solar spectrum and agrees well with the simulation. Our simple process offers a promising material for solar-thermal devices.

  1. Near-perfect broadband absorption from hyperbolic metamaterial nanoparticles

    Science.gov (United States)

    Riley, Conor T.; Smalley, Joseph S. T.; Brodie, Jeffrey R. J.; Fainman, Yeshaiahu; Sirbuly, Donald J.; Liu, Zhaowei

    2017-02-01

    Broadband absorbers are essential components of many light detection, energy harvesting, and camouflage schemes. Current designs are either bulky or use planar films that cause problems in cracking and delamination during flexing or heating. In addition, transferring planar materials to flexible, thin, or low-cost substrates poses a significant challenge. On the other hand, particle-based materials are highly flexible and can be transferred and assembled onto a more desirable substrate but have not shown high performance as an absorber in a standalone system. Here, we introduce a class of particle absorbers called transferable hyperbolic metamaterial particles (THMMP) that display selective, omnidirectional, tunable, broadband absorption when closely packed. This is demonstrated with vertically aligned hyperbolic nanotube (HNT) arrays composed of alternating layers of aluminum-doped zinc oxide and zinc oxide. The broadband absorption measures >87% from 1,200 nm to over 2,200 nm with a maximum absorption of 98.1% at 1,550 nm and remains large for high angles. Furthermore, we show the advantages of particle-based absorbers by transferring the HNTs to a polymer substrate that shows excellent mechanical flexibility and visible transparency while maintaining near-perfect absorption in the telecommunications region. In addition, other material systems and geometries are proposed for a wider range of applications.

  2. Broadband illumination of superconducting pair breaking photon detectors

    Science.gov (United States)

    Guruswamy, T.; Goldie, D. J.; Withington, S.

    2016-04-01

    Understanding the detailed behaviour of superconducting pair breaking photon detectors such as Kinetic Inductance Detectors (KIDs) requires knowledge of the nonequilibrium quasiparticle energy distributions. We have previously calculated the steady state distributions resulting from uniform absorption of monochromatic sub gap and above gap frequency radiation by thin films. In this work, we use the same methods to calculate the effect of illumination by broadband sources, such as thermal radiation from astrophysical phenomena or from the readout system. Absorption of photons at multiple above gap frequencies is shown to leave unchanged the structure of the quasiparticle energy distribution close to the superconducting gap. Hence for typical absorbed powers, we find the effects of absorption of broadband pair breaking radiation can simply be considered as the sum of the effects of absorption of many monochromatic sources. Distribution averaged quantities, like quasiparticle generation efficiency η, match exactly a weighted average over the bandwidth of the source of calculations assuming a monochromatic source. For sub gap frequencies, however, distributing the absorbed power across multiple frequencies does change the low energy quasiparticle distribution. For moderate and high absorbed powers, this results in a significantly larger η-a higher number of excess quasiparticles for a broadband source compared to a monochromatic source of equal total absorbed power. Typically in KIDs the microwave power absorbed has a very narrow bandwidth, but in devices with broad resonance characteristics (low quality factors), this increase in η may be measurable.

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

    CERN Document Server

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

    2015-01-01

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

  4. Implementation of broadband low-sidelobe beamforming in time domain

    Institute of Scientific and Technical Information of China (English)

    YANG Yixin; SUN Chao; MA Yuanliang

    2003-01-01

    In modern active and passive sonar systems, broadband beamforming for acoustic arrays is widely used to suppress unwanted interference and to detect target signals of interest. A broadband low sidelobe beamforming scheme in time domain is proposed in this paper. The first step of this scheme is to delay the outputs of each element in the acoustic array by a tapped-delay-line (TDL) to accomplish the integer part of the time delay need to form a beam. Then, finite impulse response (FIR) digital filters are used to implement the fractional part of the time delay. The weighting coefficients for all array elements at different frequencies to realize the low sidelobe beams are also implemented with the FIR digital filters. Finally, the outputs of the digital filters are summed up to yield the time domain beam output. The design of low sidelobe beam pattern and that of the FIR digital filters are two crucial technical issues in this beamforming procedure. The low sidelobe beams of each sub-band are designed using the optimized beam synthesis approach based on the principle of MVDR beamforming. An improved adaptive approach are used for the design of FIR digital filters, and the design requirements of these filters were specified by the weights of low sidelobe beams of each sub-band over the broad frequency band. Results of computer simulation for a twelve-element arc array show that the beamforming scheme is very effective in forming low sidelobe broadband beam.

  5. Freely-tunable broadband polarization rotator for terahertz waves

    Science.gov (United States)

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

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

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

    Science.gov (United States)

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

    2016-08-01

    In this paper, one kind of helix-like chiral metamaterial which can be realized by multiple conventional lithography or electron beam lithographic techniques is proposed to have a broadband bianisotropic optical response analogous to helical metamaterials. On the basis of twisted metamaterials, via tailoring the relative orientation within the lattice, the anisotropy of arcs is converted into magneto-electric coupling of closely spaced arc pairs, which leads to a broad bianisotropic optical response. By connecting the adjacent upper and lower arcs, the coupling of metasurface pairs is transformed into the coupling of the three-dimensional inclusions, and provides a much broader and higher bianisotropic optical response. For only a four-layer helix-like metamaterial, the maximum extinction ratio can reach 19.7. The operation band is in the wavelength range of 4.69 μm to 8.98 μm with an average extinction ratio of 6.9. And the transmittance for selective polarization is above 0.8 in the entire operation band. Such a structure is a promising candidate for integratable and scalable broadband circular polarizers, especially it has great potential to act as a broadband circular micropolarizer in the field of the full-Stokes division of focal plane polarimeters.

  7. Origin of Broadband Electrostatic Waves in Earth's Magnetotail

    Science.gov (United States)

    Grabbe, Crockett

    1999-11-01

    Since the discovery on Geotail of spiky pulses on broadband electrostatic "noise" (BEN) in the plasma sheet boundary layer (PSBL), the principle theoretical model pursued involves solitary waves associated with Bernstein-Greene-Kruskal (BGK) modes. That model was set forth because of evidence for nonlinear signatures in the waves, and implicitly assumes BEN for all frequencies and locations occurs well past the linear stage of growth. However, simulations using various versions of this model have been idealized, ignoring physical parameters such as the background magnetic field until recently. A new theory has been proposed by the author in which the strong trapping nonlinearities (so that BGK modes can evolve) are limited to the highest frequencies (near the plasma frequency), whereas the broadband bulk of the lower frequency spectrum (up to 0.1-0.2 ω_pe arises from wide-angle beam instabilities where the magnetic field plays a crucial role and where trapping is too weak for BGK-type modes. Broadband electrostatic Wave data from ISEE-1, ISEE-3 and Polar are presented that support the new model.

  8. A NOVEL QOS SCHEDULING FOR WIRELESS BROADBAND NETWORKS

    Directory of Open Access Journals (Sweden)

    D. David Neels Pon Kumar

    2010-09-01

    Full Text Available During the last few years, users all over the world have become more and more familiar to the availability of broadband access. When users want broadband Internet service, they are generally restricted to a DSL (Digital Subscribers Line, or cable-modem-based connection. Proponents are advocating worldwide interoperability for microwave access (WiMAX, a technology based on an evolving standard for point-to multipoint wireless networking. Scheduling algorithms that support Quality of Service (QoS differentiation and guarantees for wireless data networks are crucial to the deployment of broadband wireless networks. The performance affecting parameters like fairness, bandwidth allocation, throughput, latency are studied and found out that none of the conventional algorithms perform effectively for both fairness and bandwidth allocation simultaneously. Hence it is absolutely essential for an efficient scheduling algorithm with a better trade off for these two parameters. So we are proposing a novel Scheduling Algorithm using Fuzzy logic and Artificial neural networks that addresses these aspects simultaneously. The initial results show that a fair amount of fairness is attained while keeping the priority intact. Results also show that maximum channel utilization is achieved with a negligible increment in processing time.

  9. Low frequency signals analysis from broadband seismometers records

    Science.gov (United States)

    Hsu, Po-Chin

    2016-04-01

    Broadband seismometers record signals over a wide frequency band, in which the high-frequency background noise is usually associated with human activities, such as cars, trains and factory-related activities. Meanwhile, the low-frequency signals are generally linked to the microseisms, atmospheric phenomena and oceanic wave movement. In this study, we selected the broadband seismometer data recorded during the pass of the typhoons with different moving paths, such as Doksuri in 2012, Trami and Kong-Rey in 2013, Hagibis and Matmo in 2014. By comparing the broadband seismic data, the meteorological information, and the marine conditions, we attempt to understand the effect of the meteorological conditions on the low-frequency noise. The result shows that the broadband station located along the southwestern coast of Taiwan usually have relatively higher background noise value, while the inland stations were characterized by lower noise energy. This rapid decay of the noise energy with distance from the coastline suggest that the low frequency noise could be correlated with the oceanic waves. In addition, the noise energy level increases when the distance from the typhoon and the station decreases. The enhanced frequency range is between 0.1~0.3 Hz, which is consistent with the effect caused by the interference of oceanic waves as suggested by the previous studies. This observation indicates that when the pass of typhoon may reinforce the interaction of oceanic waves and caused some influence on the seismic records. The positive correlation between the significant wave height and the noise energy could also give evidence to this observation. However, we found that the noise energy is not necessarily the strongest when the distance from typhoon and the station is the shortest. This phenomenon seems to be related to the typhoon path. When the typhoon track is perpendicular to the coastline, the change of noise energy is generally more significantly; whereas less energy

  10. ANALYSIS OF THE ISSUES OF EFFECTIVE BROADBAND MEDIA SERVICES DEPLOYMENT IN THE COMPUTER COMMUNICATION

    Directory of Open Access Journals (Sweden)

    Dr.S.S.Riaz Ahamed

    2010-06-01

    Full Text Available Fast Internet access barely scratches the surface of the powers of broadband, DSL, and IP technology, which, combined in broadband media services, will connect people and businesses around the world like never before. Broadband media services will put the consumer in total control by enabling personal, custom, on-demand viewing of entertainment, e-learning, video games, and other types of content. Individuals will choose what they want to hear, see, or be entertained by on their own, and people will no longer have to plan around preconceived broadcast schedules for home entertainment. A broadband media service provides endless possibilities for consumers to choose and personalize their entertainment and infotainment. A brief history tracing the evolution of broadband media services will be presented, along with descriptions of multimedia standards, potential services, and the roles of the various entities involved in creating broadband media services–network providers, content providers, services providers, and businesses and consumers.

  11. 将宽带梦想接入现实%Broadband Dream Accessing Reality

    Institute of Scientific and Technical Information of China (English)

    夏竞辉

    2005-01-01

    Now the developing roadmap of “Industrialization Driven by Information Technology” and the industry strategy of “Telecom Giant” are both conformed, which means that the development of broadband industry and its market will be supported by the government, In addition, the Digital Olympics plan of “Establishing the 2008 Olympics as the First Real Broadband Olympics” will give great powers to the broadband development in China, In view of the great importance of broadband development now in China, in this issue “New Telecom Salon” focuses on broadband services development, And we are horned to invite all the experts in this field. They will show us the new image of broadband industry development by discussion here,

  12. An 88-nm broadband ASE source with bismuth-based erbium-doped fiber

    Institute of Scientific and Technical Information of China (English)

    Yanyong Wang; Runchang Zhao; Huanmin Bao; Xiaojun Jiang; Tianxin Yang; Shichen Li; Zhan Sui; Mingzhong Li; Lei Ding; Yiming Luo

    2005-01-01

    @@ A broadband amplified spontaneous emission (ASE) source of 88 nm is demonstrated using novel bismuthbased erbium-doped fiber (EDF) with the length of only 49.2 cm in a bi-direction pumping scheme. The maximum output power of 14.3 dBm is obtained under total pump power of 162 mW. The fiber loop mirror which works as a broadband reflector is responsible for the broadband output spectrum of this source according to the experiments.

  13. FUZZY REQUIREMENT BASED STRATEGY OF QoS SERVICE FOR BROADBAND TELECOMMUNICATION NETWORKS

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A fuzzy requirement based strategy for QoS service in broadband networks was presented. With the analysis of QoS service in ATM networks and broadband IP networks, it gave a requirement-based strategy for QoS service application with Fuzzy language evaluation principles. The requirement parameters are chosen according to the WANT/COST rule, and a fuzzy set is constructed to realize the fuzzy determinant. The simulation results show that it is useful to evaluate the QoS service in broadband networks, and to effectively simplify the access protocols and solve the billing issues in broadband networks.

  14. The monterey bay broadband ocean bottom seismic observatory

    Directory of Open Access Journals (Sweden)

    R. Uhrhammer

    2006-06-01

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

  15. Acoustic Environment of Admiralty Inlet: Broadband Noise Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jinshan; Deng, Zhiqun; Martinez, Jayson J.; Carlson, Thomas J.; Myers, Joshua R.; Weiland, Mark A.; Jones, Mark E.

    2011-09-30

    Admiralty Inlet has been selected as a potential tidal energy site. It is located near shipping lanes, is a highly variable acoustic environment, and is frequented by the highly endangered southern resident killer whale (SRKW). Resolving environmental impacts is the first step to receiving approval to deploy tidal turbines at Admiralty Inlet. Of particular concern is the potential for blade strike or other negative interactions between the SRKW and the tidal turbine. A variety of technologies including passive and active monitoring systems are being considered as potential tools to determine the presence of SRKW in the vicinity of the turbines. Broadband noise level measurements are critical for the determination of design and operation specifications of all marine and hydrokinetic energy capture technologies. Acoustic environment data at the proposed site was acquired at different depths using a cabled vertical line array (VLA) with four calibrated hydrophones. The sound pressure level (SPL) power spectrum density was estimated based on the fast Fourier transform. This study describes the first broadband SPL measurements for this site at different depths with frequency ranging from 10 kHz to 480 kHz in combination with other information. To understand the SPL caused by this bedload transport, three different pressure sensors with temperature and conductivity were also assembled on the VLA to measure the conditions at the hydrophone deployment depth. The broadband SPL levels at frequency ranges of 3 kHz to 7 kHz as a function of depth were estimated. Only the hydrophone at an average depth of 40 m showed the strong dependence of SPL with distance from the bottom, which was possibly caused by the cobbles shifting on the seabed. Automatic Identification System data were also studied to understand the SPL measurements.

  16. Behavioral sensitivity to broadband binaural localization cues in the ferret.

    Science.gov (United States)

    Keating, Peter; Nodal, Fernando R; Gananandan, Kohilan; Schulz, Andreas L; King, Andrew J

    2013-08-01

    Although the ferret has become an important model species for studying both fundamental and clinical aspects of spatial hearing, previous behavioral work has focused on studies of sound localization and spatial release from masking in the free field. This makes it difficult to tease apart the role played by different spatial cues. In humans and other species, interaural time differences (ITDs) and interaural level differences (ILDs) play a critical role in sound localization in the azimuthal plane and also facilitate sound source separation in noisy environments. In this study, we used a range of broadband noise stimuli presented via customized earphones to measure ITD and ILD sensitivity in the ferret. Our behavioral data show that ferrets are extremely sensitive to changes in either binaural cue, with levels of performance approximating that found in humans. The measured thresholds were relatively stable despite extensive and prolonged (>16 weeks) testing on ITD and ILD tasks with broadband stimuli. For both cues, sensitivity was reduced at shorter durations. In addition, subtle effects of changing the stimulus envelope were observed on ITD, but not ILD, thresholds. Sensitivity to these cues also differed in other ways. Whereas ILD sensitivity was unaffected by changes in average binaural level or interaural correlation, the same manipulations produced much larger effects on ITD sensitivity, with thresholds declining when either of these parameters was reduced. The binaural sensitivity measured in this study can largely account for the ability of ferrets to localize broadband stimuli in the azimuthal plane. Our results are also broadly consistent with data from humans and confirm the ferret as an excellent experimental model for studying spatial hearing.

  17. Transonic Tones and Excess Broadband Noise in Overexpanded Supersonic Jets

    Science.gov (United States)

    Zaman, Khairul B. M. Q.

    2009-01-01

    Noise characteristics of convergent-divergent (C-D) nozzles in the overexpanded regime are the focus of this paper. The flow regime is encountered during takeoff and landing of certain airplanes and also with rocket nozzles in launch-pad environment. Experimental results from laboratory-scale single nozzles are discussed. The flow often undergoes a resonance accompanied by emission of tones (referred to as transonic tones). The phenomenon is different from the well-known screech tones. Unlike screech, the frequency increases with increasing supply pressure. There is a staging behavior odd harmonic stages occur at lower pressures while the fundamental occurs in a range of relatively higher pressures. A striking feature is that tripping of the nozzle s internal boundary layer tends to suppress the resonance. However, even in the absence of tones the broadband levels are found to be high. That is, relative to a convergent case and at same pressure ratio, the C-D nozzles are found to be noisier, often by more than 10dB. This excess broadband noise (referred to as EBBN) is further explored. Its characteristics are found to be different from the well-known broadband shockassociated noise ( BBSN ). For example, while the frequency of the BBSN peak varies with observation angle no such variation is noted with EBBN. The mechanisms of the transonic tone and the EBBN are not completely understood yet. They appear to be due to unsteady shock motion inside the nozzle. The shock drives the flow downstream like a vibrating diaphragm, and resonance takes place similarly as with acoustic resonance of a conical section having one end closed and the other end open. When the boundary layer is tripped, apparently a breakdown of azimuthal coherence suppresses the resonance. However, there is still unsteady shock motion albeit with superimposed randomness. Such random motion of the internal shock and its interaction with the separated boundary layer produces the EBBN.

  18. Broadband Ground Motion Simulations for the Puente Hills Fault System

    Science.gov (United States)

    Graves, R. W.

    2005-12-01

    Recent geologic studies have identified the seismic potential of the Puente Hills fault system. This system is comprised of multiple blind thrust segments, a portion of which ruptured in the Mw 5.9 Whittier-Narrows earthquake. Rupture of the entire system could generate a Mw 7.2 (or larger) earthquake. To assess the potential hazard posed by the fault system, we have simulated the response for several earthquake scenarios. These simulations are unprecedented in scope and scale. Broadband (0-10 Hz) ground motions are computed at 66,000 sites, covering most of the LA metropolitan region. Low frequency (f 1 Hz) motions are calculated using a stochastic approach. We consider scenarios ranging from Mw 6.7 to Mw 7.2, including both high and low stress drop events. Finite-fault rupture models for these scenarios are generated following a wavenumber filtering technique (K-2 model) that has been calibrated against recent earthquakes. In all scenarios, strong rupture directivity channels large amplitude pulses of motion directly into the Los Angeles basin, which then propagate southward as basin surface waves. Typically, the waveforms near downtown Los Angeles are dominated by a strong, concentrated pulse of motion. At Long Beach (across the LA basin from the rupture) the waveforms are dominated by late arriving longer period surface waves. The great density of sites used in the calculation allows the construction of detailed maps of various ground motion parameters (PGA, PGV, SA), as well as full animations of the propagating broadband wave field. Additionally, the broadband time histories are available for use in non-linear response analyses of built structures.

  19. An Integrated Broadband Switching System with Narrowband Service Support

    Institute of Scientific and Technical Information of China (English)

    GONG Xiangyang; ZHANG Peng; CHENG Shiduan

    2001-01-01

    It is considered that ATM is not suitable for traditional narrowband services such as voice because of large adapting delay. In this paper,we present an ATM-based broadband switching system, which is capable of supporting narrowband services. A composite cell adapting method is adopted in this system to reduce adapting delay and guarantee QoS (Quality of Service). In the realized system, several key parameters have been measured. The results prove that it can guarantee perfect QoS and relative high bandwidth efficiency.

  20. BaMAP: A Broadband Multimedia Application Platform

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    In this paper, a broadband multimedia application platform, BaMAP, is introduced. The BaMAP aims to offer content and service providers a good integrated environment for efficient content production, management, delivery and sharing. It supports large-scale hierarchical storage, as well as mechanisms for content distribution and queries from remote nodes. The on-demand service, part of the BaMAP, offers two access interfaces, DVB-C and IP, which allow the platform to run on most of the existing access networks.

  1. Faster Broadband, but Who Needs It'?

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    According to New York Times on October 24, the global mobile industry is making the same leap of faith with Long Term Evolution, the technology behind the super-fast wireless broadband net- works now being switched on around the world. In October, mobile operators are building 174 LTE networks in 64 countries, according to the GSA Association, an industry group of net- work equipment makers based in Zurich. With its faster speed and greater capacity to handle the explosive growth in mobile data traffic, operators are wagering that LTE will be critical to future profitability.

  2. A SYNCHRONIZATION ALGORITHM FOR HF (HIGH FREQUENCY) BROADBAND OFDM SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Yang Lei; Zhang You'ai

    2008-01-01

    In this letter, a kind of associated synchronization algorithm which is suitable for HF (High Frequency) broadband OFDM (Orthogonal Frequency Division Multiplexing) system is presented based on describing and constructing the GMW (Gorden, Mills and Welch) sequence. The algorithm is based on the Schmidl and Minn's symbol timing principle, the constructed GMW sequence is transmitted and disposed, and the synchronization is adjudicated using the correlation of GMW sequence. The simulation result indicates that this algorithm has high performance synchronization ability under the low SNR (Signal to Noise Ratio) at two different kinds of channel models.

  3. Simulation of a Broadband Antenna with the Method of Moments

    Directory of Open Access Journals (Sweden)

    M. Czarnecki

    2005-12-01

    Full Text Available In the paper selected problems of computer simulations of abroadband antenna containing large metallic surfaces with the Method ofMoments have been discussed. A novel broadband combined spiral-disconeantenna, built of a complementary spiral and a cone has been analyzed.Since the antenna contains large metallic surfaces wire-grid models hadto be developed in order to simulate the antenna with the thin-wirekernel method of moments. Several wire-grid models of the antenna havebeen proposed and analyzed. The simulation results for input impedancehave been compared to those obtained from measurements and the bestmodel of the antenna has been identified.

  4. Broadband manipulation of acoustic wavefronts by pentamode metasurface

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Ye; Wei, Qi, E-mail: weiqi@nju.edu.cn; Cheng, Ying [Key Laboratory of Modern Acoustics, Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); Xu, Zheng [School of Physics Science and Engineering, Tongji University, Shanghai 200092 (China); Liu, Xiaojun, E-mail: liuxiaojun@nju.edu.cn [Key Laboratory of Modern Acoustics, Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190 (China)

    2015-11-30

    An acoustic metasurface with a sub-wavelength thickness can manipulate acoustic wavefronts freely by the introduction of abrupt phase variation. However, the existence of a narrow bandwidth and a low transmittance limits further applications. Here, we present a broadband and highly transparent acoustic metasurface based on a frequency-independent generalized acoustic Snell's law and pentamode metamaterials. The proposal employs a gradient velocity to redirect refracted waves and pentamode metamaterials to improve impedance matching between the metasurface and the background medium. Excellent wavefront manipulation based on the metasurface is further demonstrated by anomalous refraction, generation of non-diffracting Bessel beam, and sub-wavelength flat focusing.

  5. Potential roles of optical interconnections within broadband switching modules

    Science.gov (United States)

    Lalk, Gail R.; Habiby, Sarry F.; Hartman, Davis H.; Krchnavek, Robert R.; Wilson, Donald K.; Young, Kenneth C., Jr.

    1991-04-01

    An investigation of potential physical design bottlenecks in future broadband telecommunication switches has led to the identification of several areas where optical interconnections may play a role in the practical realization of required system performance. In the model used the speed and interconnection densities as well as requirements for ease-of-access and efficient power utilization challenge conventional partitioning and packaging strategies. Potential areas where optical interconnections may relieve some of the physical design bottlenecks include fiber management at the customer interface to the switch routing and distribution of high-density interconnections within the fabric of the switch and backplane interconnections to increase system throughput.

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

    CERN Document Server

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

    1998-01-01

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

  7. Fast Approximate Broadband Phase Retrieval for Segmented Systems

    Science.gov (United States)

    Jurling, Alden S.; Fienup, James R.

    2011-01-01

    Broadband phase retrieval needed when: a) Narrow spectral filters are unavailable. b) Dim sources. c) Low throughput due to misalignment. d) Short exposures times. i.e., Pointing instability (space); and Atmospheric instability (ground based AO). Traditional approach is computationally burdensome for extreme bandwidths. Approximate approach: a) Substitute monochromatic model. b) Blur model and data. Test case performance: a) approx.270x reduction in computational cost for FGS-like test case. b) Good accuracy for monolithic system. c) Acceptable accuracy for segmented systems. i.e., Reduced by diffraction and Reduced by higher order segment model.

  8. Thermodynamic Upper Bound on Broadband Light Coupling with Photonic Structures

    KAUST Repository

    Yu, Zongfu

    2012-10-01

    The coupling between free space radiation and optical media critically influences the performance of optical devices. We show that, for any given photonic structure, the sum of the external coupling rates for all its optical modes are subject to an upper bound dictated by the second law of thermodynamics. Such bound limits how efficient light can be coupled to any photonic structure. As one example of application, we use this upper bound to derive the limit of light absorption in broadband solar absorbers. © 2012 American Physical Society.

  9. Czerny-Turner imaging spectrometer for broadband spectral simultaneity

    Institute of Scientific and Technical Information of China (English)

    Qingsheng Xue; Shurong Wang; Futian Li

    2009-01-01

    A modified asymmetrical Czerny-Turner arrangement with a fixed plane grating is proposed to correct aberrations over a broadband spectral range by analyzing the dependence of aberrations for different wavelengths.The principle of design is deduced in detail.We compare the performance of this modified Czerny-Turner imaging spectrometer with that of the existing Czerny-Turner arrangement by using a practical Czerny-Turner imaging spectrometer example.The excellent performance of the modified imaging spectrometer is confirmed by simulation with ZEMAX software.

  10. Compact U-Slotted Antenna for Broadband Radar Applications

    Directory of Open Access Journals (Sweden)

    S. Costanzo

    2013-01-01

    Full Text Available The original U-shaped patch antenna is properly modified in this work to provide a compact and broadband antenna configuration with reduced cross-polar effects, well suitable for modern radar applications. The proposed antenna layout is applied to design, realize, and test two different prototypes working at P-band and C-band, typically adopted for ground-penetrating radar. The experimental results successfully demonstrate a large operating bandwidth between 15% and 20%, a significant reduction of size (about half of the standard configuration, and a low cross-polarization level within the operating frequency range.

  11. A broadband micro-machined far-infrared absorber

    Science.gov (United States)

    Wollack, E. J.; Datesman, A. M.; Jhabvala, C. A.; Miller, K. H.; Quijada, M. A.

    2016-05-01

    The experimental investigation of a broadband far-infrared meta-material absorber is described. The observed absorptance is >0.95 from 1 to 20 THz (300-15 μm) over a temperature range spanning 5-300 K. The meta-material, realized from an array of tapers ≈100 μm in length, is largely insensitive to the detailed geometry of these elements and is cryogenically compatible with silicon-based micro-machined technologies. The electromagnetic response is in general agreement with a physically motivated transmission line model.

  12. PHEMT Distributed Power Amplifier Adopting Broadband Impedance Transformer

    DEFF Research Database (Denmark)

    Narendra, K.; Limiti, E.; Paoloni, C.;

    2013-01-01

    A non-uniform drain line distributed power amplifier (DPA) employing a broadband impedance transformer is presented. The DPA is based on GaAs PHEMT technology. The impedance transformer employs asymmetric coupled lines and transforms a low output impedance of the amplifier to a standard 50 Ω tran...... transmission line. The output power of approximately 600 mW, with an associated gain of 9 dB and PAE greater than 30 percent, is demonstrated in the frequency range from 10 to 1800 MHz....

  13. Broad-band photometric evolution of star clusters

    OpenAIRE

    Girardi, Leo

    2001-01-01

    I briefly introduce a database of models that describe the evolution of star clusters in several broad-band photometric systems. Models are based on the latest Padova stellar evolutionary tracks - now including the alpha-enhanced case and improved AGB models - and a revised library of synthetic spectra from model atmospheres. As of today, we have revised isochrones in Johnson-Cousins-Glass, HST/WFPC2, HST/NICMOS, Thuan-Gunn, and Washington systems. Several other filter sets are included in a ...

  14. Design of a Broadband Inverted Conical Quadrifilar Helix Antenna

    Directory of Open Access Journals (Sweden)

    Jingyan Mo

    2016-01-01

    Full Text Available This paper introduces the design of a broadband inverted conical circularly polarized quadrifilar helix antenna (QHA. The antenna has many good characteristics, including wide beam and broad bandwidth, which are achieved by utilizing inverted conical geometry and adjusting the dimensions of the inverted conical support. The antenna is fed by a wideband network to provide 90° phase difference between the four arms with constant amplitude. The antenna impedance and axial ratio bandwidth values are more than 39% and 31.5%, respectively. The measured results coincide well with the simulated ones, which verified the effectiveness of the proposed design.

  15. A Broadband Micro-machined Far-Infrared Absorber

    CERN Document Server

    Wollack, Edward J; Jhabvala, Christine A; Miller, Kevin H; Quijada, Manuel A

    2016-01-01

    The experimental investigation of a broadband far-infrared meta-material absorber is described. The observed absorptance is $>\\,0.95$ from ${\\rm 1-20\\,THz}$ (${\\rm 300-15\\,\\mu m}$) over a temperature range spanning ${\\rm 5-300\\,K}$. The meta-material, realized from an array of tapers ${\\rm \\approx 100\\,\\mu m}$ in length, is largely insensitive to the detailed geometry of these elements and is cryogenically compatible with silicon-based micro-machined technologies. The electromagnetic response is in general agreement with a physically motivated transmission line model.

  16. Broadband unidirectional behavior of electromagnetic waves based on transformation optics

    Science.gov (United States)

    Zang, Xiaofei; Zhu, Yiming; Ji, Xuebin; Chen, Lin; Hu, Qing; Zhuang, Songlin

    2017-01-01

    High directive antennas are fundamental elements for microwave communication and information processing. Here, inspired by the method of transformation optics, we propose and demonstrate a transformation medium to control the transmission path of a point source, resulting in the unidirectional behavior of electromagnetic waves (directional emitter) without any reflectors. The network of inductor-capacitor transmission lines is designed to experimentally realize the transformation medium. Furthermore, the designed device can work in a broadband frequency range. The unidirectional-manner-based device demonstrated in this work will be an important step forward in developing a new type of directive antennas.

  17. Frequency Comb Assisted Broadband Precision Spectroscopy with Cascaded Diode Lasers

    CERN Document Server

    Liu, Junqiu; Pfeiffer, Martin H P; Kordts, Arne; Kamel, Ayman N; Guo, Hairun; Geiselmann, Michael; Kippenberg, Tobias J

    2016-01-01

    Frequency comb assisted diode laser spectroscopy, employing both the accuracy of an optical frequency comb and the broad wavelength tuning range of a tunable diode laser, has been widely used in many applications. In this letter we present a novel method using cascaded frequency agile diode lasers, which allows extending the measurement bandwidth to 37.4 THz (1355 to 1630 nm) at MHz resolution with scanning speeds above 1 THz/s. It is demonstrated as a useful tool to characterize a broadband spectrum for molecular spectroscopy and in particular it enables to characterize the dispersion of integrated microresonators up to the fourth order.

  18. Subcarrier multiplexing tolerant dispersion transmission system employing optical broadband sources.

    Science.gov (United States)

    Grassi, Fulvio; Mora, José; Ortega, Beatriz; Capmany, José

    2009-03-16

    This paper presents a novel SCM optical transmission system for next-generation WDM-PONs combining broadband optical sources and a Mach-Zehnder interferometric structure. The approach leeds to transport RF signals up to 50 GHz being compatible with RoF systems since a second configuration has been proposed in order to overcome dispersion carrier suppression effect using DSB modulation. The theoretical analysis validates the potentiality of the system also considering the effects of the dispersion slope over the transmission window.

  19. Derivation of Improved Surface and TOA Broadband Fluxes Using CERES-derived Narrowband-to-Broadband Coefficients

    Science.gov (United States)

    Khaiyer, Mandana M.; Doelling, David R.; Chan, Pui K.; Nordeen, MIchele L.; Palikonda, Rabindra; Yi, Yuhong; Minnis, Patrick

    2006-01-01

    Satellites can provide global coverage of a number of climatically important radiative parameters, including broadband (BB) shortwave (SW) and longwave (LW) fluxes at the top of the atmosphere (TOA) and surface. These parameters can be estimated from narrowband (NB) Geostationary Operational Environmental Satellite (GOES) data, but their accuracy is highly dependent on the validity of the narrowband-to-broadband (NB-BB) conversion formulas that are used to convert the NB fluxes to broadband values. The formula coefficients have historically been derived by regressing matched polarorbiting satellite BB fluxes or radiances with their NB counterparts from GOES (e.g., Minnis et al., 1984). More recently, the coefficients have been based on matched Earth Radiation Budget Experiment (ERBE) and GOES-6 data (Minnis and Smith, 1998). The Clouds and the Earth's Radiant Energy Budget (CERES see Wielicki et al. 1998)) project has recently developed much improved Angular Distribution Models (ADM; Loeb et al., 2003) and has higher resolution data compared to ERBE. A limited set of coefficients was also derived from matched GOES-8 and CERES data taken on Topical Rainfall Measuring Mission (TRMM) satellite (Chakrapani et al., 2003; Doelling et al., 2003). The NB-BB coefficients derived from CERES and the GOES suite should yield more accurate BB fluxes than from ERBE, but are limited spatially and seasonally. With CERES data taken from Terra and Aqua, it is now possible to derive more reliable NB-BB coefficients for any given area. Better TOA fluxes should translate to improved surface radiation fluxes derived using various algorithms. As part of an ongoing effort to provide accurate BB flux estimates for the Atmospheric Radiation Measurement (ARM) Program, this paper documents the derivation of new NB-BB coefficients for the ARM Southern Great Plains (SGP) domain and for the Darwin region of the Tropical Western Pacific (DTWP) domain.

  20. Broadband acoustic scattering measurements of underwater unexploded ordnance (UXO).

    Science.gov (United States)

    Bucaro, J A; Houston, B H; Saniga, M; Dragonette, L R; Yoder, T; Dey, S; Kraus, L; Carin, L

    2008-02-01

    In order to evaluate the potential for detection and identification of underwater unexploded ordnance (UXO) by exploiting their structural acoustic response, we carried out broadband monostatic scattering measurements over a full 360 degrees on UXO's (two mortar rounds, an artillery shell, and a rocket warhead) and false targets (a cinder block and a large rock). The measurement band, 1-140 kHz, includes a low frequency structural acoustics region in which the wavelengths are comparable to or larger than the target characteristic dimensions. In general, there are aspects that provide relatively high target strength levels ( approximately -10 to -15 dB), and from our experience the targets should be detectable in this structural acoustics band in most acoustic environments. The rigid body scattering was also calculated for one UXO in order to highlight the measured scattering features involving elastic responses. The broadband scattering data should be able to support feature-based separation of UXO versus false targets and identification of various classes of UXO as well.

  1. Amplifier based broadband pixel for sub-millimeter wave imaging

    Science.gov (United States)

    Sarkozy, Stephen; Drewes, Jonathan; Leong, Kevin M. K. H.; Lai, Richard; Mei, X. B. (Gerry); Yoshida, Wayne; Lange, Michael D.; Lee, Jane; Deal, William R.

    2012-09-01

    Broadband sub-millimeter wave technology has received significant attention for potential applications in security, medical, and military imaging. Despite theoretical advantages of reduced size, weight, and power compared to current millimeter wave systems, sub-millimeter wave systems have been hampered by a fundamental lack of amplification with sufficient gain and noise figure properties. We report a broadband pixel operating from 300 to 340 GHz, biased off a single 2 V power supply. Over this frequency range, the amplifiers provide > 40 dB gain and mobility transistor technology, based on a sub-50 nm gate and indium arsenide composite channel with a projected maximum oscillation frequency fmax>1.0 THz. The first sub-millimeter wave-based images using active amplification are demonstrated as part of the Joint Improvised Explosive Device Defeat Organization Longe Range Personnel Imager Program. This development and demonstration may bring to life future sub-millimeter-wave and THz applications such as solutions to brownout problems, ultra-high bandwidth satellite communication cross-links, and future planetary exploration missions.

  2. A highly innovative global broadband mobile communication system concept

    Science.gov (United States)

    Wittig, Manfred

    2010-04-01

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

  3. Error and Congestion Resilient Video Streaming over Broadband Wireless

    Directory of Open Access Journals (Sweden)

    Laith Al-Jobouri

    2015-04-01

    Full Text Available In this paper, error resilience is achieved by adaptive, application-layer rateless channel coding, which is used to protect H.264/Advanced Video Coding (AVC codec data-partitioned videos. A packetization strategy is an effective tool to control error rates and, in the paper, source-coded data partitioning serves to allocate smaller packets to more important compressed video data. The scheme for doing this is applied to real-time streaming across a broadband wireless link. The advantages of rateless code rate adaptivity are then demonstrated in the paper. Because the data partitions of a video slice are each assigned to different network packets, in congestion-prone wireless networks the increased number of packets per slice and their size disparity may increase the packet loss rate from buffer overflows. As a form of congestion resilience, this paper recommends packet-size dependent scheduling as a relatively simple way of alleviating the buffer-overflow problem arising from data-partitioned packets. The paper also contributes an analysis of data partitioning and packet sizes as a prelude to considering scheduling regimes. The combination of adaptive channel coding and prioritized packetization for error resilience with packet-size dependent packet scheduling results in a robust streaming scheme specialized for broadband wireless and real-time streaming applications such as video conferencing, video telephony, and telemedicine.

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

    Science.gov (United States)

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

    2013-09-01

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

  5. Ultra-broadband microwave metamaterial absorber based on resistive sheets

    Science.gov (United States)

    Kim, Y. J.; Yoo, Y. J.; Hwang, J. S.; Lee, Y. P.

    2017-01-01

    We investigate a broadband perfect absorber for microwave frequencies, with a wide incident angle, using resistive sheets, based on both simulation and experiment. The absorber uses periodically-arranged meta-atoms, consisting of snake-shape metallic patterns and metal planes separated by three resistive sheet layers between four dielectric layers. We demonstrate the mechanism of the broadband by impedance matching with free space, and the distribution of surface currents at specific frequencies. In simulation, the absorption was over 96% in 1.4-6.0 GHz. The corresponding experimental absorption band over 96% was 1.4-4.0 GHz, however, the absorption was lower than 96% in the 4.0-6.0 GHz range because of the rather irregular thickness of the resistive sheets. Furthermore, it works for wide incident angles and is relatively independent of polarization. The design is scalable to smaller sizes in the THz range. The results of this study show potential for real applications in prevention of microwave frequency exposure, with devices such as cell phones, monitors, and microwave equipment.

  6. Measuring pulse times of arrival from broadband pulsar observations

    CERN Document Server

    Liu, K; Cognard, I; Stappers, B W; Verbiest, J P W; Lee, K J; Champion, D J; Kramer, M; Freire, P C C; Karuppusamy, R

    2014-01-01

    In recent years, instrumentation enabling pulsar observations with unprecedentedly high fractional bandwidth has been under development which can be used to substantially improve the precision of pulsar timing experiments. The traditional template-matching method used to calculate pulse times-of-arrival (ToAs), may not function effectively on these broadband data due to a variety of effects such as diffractive scintillation in the interstellar medium, profile variation as a function of frequency, dispersion measure (DM) evolution and so forth. In this paper, we describe the channelised Discrete Fourier Transform method that can greatly mitigate the influence of the aforementioned effects when measuring ToAs from broadband timing data. The method is tested on simulated data, and its potential in improving timing precision is shown. We further apply the method to PSR J1909$-$3744 data collected at the Nan\\c{c}ay Radio Telescope with the Nan\\c{c}ay Ultimate Pulsar Processing Instrument. We demonstrate a removal ...

  7. Broadband infrared absorption enhancement by electroless-deposited silver nanoparticles

    Directory of Open Access Journals (Sweden)

    Gritti Claudia

    2016-07-01

    Full Text Available Decorating semiconductor surfaces with plasmonic nanoparticles (NPs is considered a viable solution for enhancing the absorptive properties of photovoltaic and photodetecting devices. We propose to deposit silver NPs on top of a semiconductor wafer by a cheap and fast electroless plating technique. Optical characterization confirms that the random array of electroless-deposited NPs improves absorption by up to 20% in a broadband of near-infrared frequencies from the bandgap edge to 2000 nm. Due to the small filling fraction of particles, the reflection in the visible range is practically unchanged, which points to the possible applications of such deposition method for harvesting photons in nanophotonics and photovoltaics. The broadband absorption is a consequence of the resonant behavior of particles with different shapes and sizes, which strongly localize the incident light at the interface of a high-index semiconductor substrate. Our hypothesis is substantiated by examining the plasmonic response of the electroless-deposited NPs using both electron energy loss spectroscopy and numerical calculations.

  8. Ultra-broadband achromatic imaging with diffractive photon sieves

    Science.gov (United States)

    Zhao, Xiaonan; Hu, Jingpei; Lin, Yu; Xu, Feng; Zhu, Xiaojun; Pu, Donglin; Chen, Linsen; Wang, Chinhua

    2016-06-01

    Diffractive optical elements suffer from large chromatic aberration due to the strong wavelength-dependent nature in diffraction phenomena, and therefore, diffractive elements can work only at a single designed wavelength, which significantly limits the applications of diffractive elements in imaging. Here, we report on a demonstration of a wavefront coded broadband achromatic imaging with diffractive photon sieves. The broadband diffraction imaging is implemented with a wavefront coded pinhole pattern that generates equal focusing power for a wide range of operating wavelength in a single thin-film element without complicated auxiliary optical system. Experimental validation was performed using an UV-lithography fabricated wavefront coded photon sieves. Results show that the working bandwidth of the wavefront coded photon sieves reaches 28 nm compared with 0.32 nm of the conventional one. Further demonstration of the achromatic imaging with a bandwidth of 300 nm is also performed with a wavefront coded photon sieves integrated with a refractive element.

  9. Generation of Broadband Electrostatic Waves in Earth's Magnetotail

    Science.gov (United States)

    Grabbe, Crockett

    2000-04-01

    The theory that broad-band electrostatic waves (BEN) in Earth's magnetotail are trapped-electron (``BGK'') modes is reexamined. Electron/ion beams analyzed for a realistic magnetized-plasma source model with κ distributions are found to drive an unstable spectrum of broad angular range over several orders of magnitude in f, up to \\(0.1-0.2\\)fpe. Analysis indicates that trapping essential for the BGK paradigm is good only at the highest f, whereas most of the spectrum has minimal trapping and can be driven by electron/ion beam instabilities. A new model is proposed in which trapped-electron modes exist only at the highest f band, whereas electron/ion beam instabilities drive the bulk of the broad-band spectrum below that. BEN wave data from ISEE-1 and ISEE-3 show large angles of propagation with respect to the magnetic field for ffce is observed only in a narrow angular range around the magnetic field and may be BGK modes. This predicts that the BEN solitary waves in the source region are not in BEN well into the lobe.

  10. The New Very Broadband Seismic Station TROLL, Antarctica

    Science.gov (United States)

    Kvaerna, Tormod; Schweitzer, Johannes; Pirli, Myrto; Roth, Michael

    2013-04-01

    Troll is the name of the Norwegian permanent research station in Dronning Maud Land, Antarctica. The research base is located inside the continent, at an elevation of about 1300 m and at a distance of about 230 km from the shelf ice border. In the first week of February 2012, a new very broadband seismic station was installed at TROLL. Contrary to many other seismic stations inside the Antarctic continent, the new seismic sensor could be installed on bedrock (migmatite), on a hill at about 300 m distance from the main buildings of the Troll research base. A bedrock installation has the advantage that seismic signals are not disturbed by multiples due to the thick Antarctic ice sheet. The equipment consists of a Streckeisen STS-2.5 broadband sensor and a Quanterra Q330HR 26 bit digitizer. All data are transferred in real time via a satellite link to NORSAR for analysis and further distribution. During the first year, the new seismic station and corresponding data transmission has been running very stably. Initial analysis of the station's event detection capability shows that the performance is comparable to, and sometimes better than, the best performing three-component stations of the International Monitoring System (IMS). We will present examples of diurnal and seasonal variations in the background noise level of the station, the observed global, regional and local seismicity, and the very exciting monitoring capabilities of icebergs drifting along the coast of Dronning Maud Land.

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

    Directory of Open Access Journals (Sweden)

    Francisco Nombela

    2015-08-01

    Full Text Available 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.

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

    Science.gov (United States)

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

    2015-08-21

    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.

  13. Broadband Spectral Investigations of SGR J1550-5418 Bursts

    CERN Document Server

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

    2012-01-01

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

  14. Broadband terahertz dynamics of propylene glycol monomer and oligomers

    Science.gov (United States)

    Koda, Shota; Mori, Tatsuya; Kojima, Seiji

    2016-12-01

    We investigated the broadband terahertz spectra (0.1-5.0 THz) of glass-forming liquids, propylene glycol (PG), its oligomers poly (propylene glycol)s (PPGs), and poly (propylene glycol) diglycidyl ether (PPG-de) using broadband terahertz time-domain spectroscopy and low-frequency Raman scattering. The numerical value of the dielectric loss at around 1.5 THz, which is the peak position of broad peaks in all samples, decreased as the molecular weight increased. Furthermore, the peak at around 1.5 THz is insensitive to the molecular weight. For PPGs, the side chain effect of the oligomer was observed in the terahertz region. Based on the experimental and calculation results for the PPGs and PPG-de, whose end groups are epoxy groups, the beginnings of the increases in the observed dielectric loss above 3.5 THz of the PPGs are assigned to the OH bending vibration. The higher value of the dielectric loss in the terahertz region for the PPG-de can be the tail of a broad peak located in the MHz region. The difference between the Raman susceptibility and dielectric loss reflects the difference in the observable molecular dynamics between the infrared and Raman spectroscopies.

  15. A novel broadband terahertz filter for photonic crystal

    Science.gov (United States)

    Luo, Yuan; Li, Yanyan; Hu, Zhangfang; Liu, Jinlan

    2016-09-01

    The influence of the change of the radius of point defect cylinders, scattering dielectric cylinders, dielectric cylinders on both sides of line waveguide on S parameter is studied. According to the resonant coupling principle between micro-cavity and waveguide, a novel broadband terahertz filter is designed. The novel filter is formed by introducing scattering dielectric cylinders into the resonant microcavity, and the point defect cylinders are composed of HgTe material and adjusting the radius of dielectric cylinders on both sides of line waveguide. Results show that the 3 dB bandwidth reaches 74.2 GHz, the return loss is less than -12.02 dB, the maximum insertion loss in-band reaches 0.35 dB and its drop efficiency is up to 96.79%. The novel terahertz filter has flat passband, sharp rejections at out-bands and its central frequency is 0.338THz. The good performances show that it can meet the requirements of high speed and broadband in terahertz atmosphere communication I window.

  16. Broadband infrared absorption enhancement by electroless-deposited silver nanoparticles

    Science.gov (United States)

    Gritti, Claudia; Raza, Søren; Kadkhodazadeh, Shima; Kardynal, Beata; Malureanu, Radu; Mortensen, N. Asger; Lavrinenko, Andrei V.

    2017-01-01

    Decorating semiconductor surfaces with plasmonic nanoparticles (NPs) is considered a viable solution for enhancing the absorptive properties of photovoltaic and photodetecting devices. We propose to deposit silver NPs on top of a semiconductor wafer by a cheap and fast electroless plating technique. Optical characterization confirms that the random array of electroless-deposited NPs improves absorption by up to 20% in a broadband of near-infrared frequencies from the bandgap edge to 2000 nm. Due to the small filling fraction of particles, the reflection in the visible range is practically unchanged, which points to the possible applications of such deposition method for harvesting photons in nanophotonics and photovoltaics. The broadband absorption is a consequence of the resonant behavior of particles with different shapes and sizes, which strongly localize the incident light at the interface of a high-index semiconductor substrate. Our hypothesis is substantiated by examining the plasmonic response of the electroless-deposited NPs using both electron energy loss spectroscopy and numerical calculations.

  17. Advances in universal scaling for broadband turbulent noise in internal flow devices

    NARCIS (Netherlands)

    Violato, D.; Jong, A.T. de; Golliard, J.

    2014-01-01

    This paper focuses on the scalability of broadband turbulent noise in internal pipe flows. It discusses a universal scaling approach for broadband turbulent noise that is based on surface acoustic power modeled by ANSYS Fluent. This investigation proposes a strategy for amplitude scaling at frequenc

  18. Extending Wireless Broadband Network Architectures with Home Gateways, Localization, and Physical Environment Surveillance

    DEFF Research Database (Denmark)

    Jelling Kristoffersen, Kåre; Kjærgaard, Mikkel Baun; Chen, Jianjun;

    2005-01-01

    Adding content is seen as the next important step in the development and deployment of broadband networks. This paper proposes three different ways of adding content to wireless broadband networks. First, the home gateway is presented as the focal point for delivery of digital services to future...

  19. Broadband terahertz polarization rotator based on a twisted parallel plate waveguide

    DEFF Research Database (Denmark)

    Kristensen, T. Bjørk; Iwaszczuk, Krzysztof; Jepsen, Peter Uhd

    2016-01-01

    A broadband polarization rotator for terahertz waves is developed by 3D printing. The device is based on a twisted parallel plate waveguide.......A broadband polarization rotator for terahertz waves is developed by 3D printing. The device is based on a twisted parallel plate waveguide....

  20. Continuous-wave broadband emitter based on a transition-metal-ion-doped waveguide

    NARCIS (Netherlands)

    Pollnau, M.; Salathé, R.P.; Bhutta, T.; Shepherd, D.P.; Eason, R.W.

    2001-01-01

    We demonstrate the suitability of a simple continuous-wave-pumped transition-metal-ion-doped waveguide as a broadband light source in the wavelength region 600–1000 nm for interferometric applications. Spatially coherent (single mode in the confined direction), spectrally broadband (~130-nm FWHM) lu

  1. The Development of Broadband in Kosovo and its Importance for the Economy

    Directory of Open Access Journals (Sweden)

    Dr.Sc. Justina Pula

    2014-06-01

    Full Text Available The better functioning of economy depends on the availability and quality of public services such as: outstanding education system, well-functioning health system, very good transportation system and other public services as well. The 21th century is seen as the century of information and communication technology. In this way the local and central governments have seen that the broadband is important like other public services. The purpose of this paper is the identification of the importance and the impacts of broadband on the development of the economy and the society. For this purpose we have surveyed in depth different theoretical and empirical literature. The literature shows that government intervention is necessary not only in the regulation of the market but also in providing broadband services and increasing the demand for these services, which in turn would enable the development of the broadband market at the same pace like other EU member states. In the last part of this paper we will show that the development of the broadband market requires a more active role of the government in the development of broadband by increasing the demand and the supply for broadband services. Regardless the fact that ARKEP is working on increasing the development level of the broadband, we will show that the existence of a well-designed governmental plan would make it possible to achieve the goal of an information society.

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

    Science.gov (United States)

    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…

  3. The Evolution of the Policy Objectives of South Korea's Broadband Convergence Network from 2004 to 2007

    Science.gov (United States)

    Menon, Siddhartha

    2011-01-01

    The purpose of this study is to explore the South Korean government's policy objectives for the Broadband Convergence Network (BcN) between 2004 and 2007. The BcN is envisioned as conduit for broadband content and applications. This paper uses generativity as a conceptual framework to determine whether the objectives for the BcN, based on a…

  4. Recovery Act Investments in Broadband: Leveraging Federal Dollars to Create Jobs and Connect America

    Science.gov (United States)

    Executive Office of the President, 2009

    2009-01-01

    Broadband touches nearly every aspect of the U.S. economy, providing Americans with unprecedented opportunities in employment, education, health care, entrepreneurship, and civic participation. For millions of Americans without adequate access to broadband, however, the possibility of falling behind in the knowledge-based economy is real.…

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

    CERN Document Server

    Rutkowski, Lucile

    2016-01-01

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

  6. Analisis Efektivitas Perangkat pada Program Desa Broadband Terpadu [Analysis of Device Effectiveness in Integrated Broadband Village Program

    Directory of Open Access Journals (Sweden)

    Hilarion Hamjen

    2016-12-01

    Full Text Available Pemerintah berkomitmen mendukung pertumbuhan e-commerce dan ekonomi digital di Indonesia untuk mencapai visi Indonesia 2020 sebagai negara ekonomi digital terbesar di Asia Tenggara. Secara fundamental diperlukan dukungan konektivitas nasional dari tingkat pusat sampai ke tingkat lokal, salah satunya melalui program KPU/USO yaitu program DBT (Desa Broadband Terpadu. Penelitian ini bertujuan untuk mengetahui efektivitas perangkat pada program DBT phase 1 dan keterkaitannya dengan konektivitas, dengan menggunakan metode analisis kepentingan kinerja dan uji statistik Chi square. Berdasarkan hasil penelitian diketahui bahwa efektivitas perangkat meliputi variabel kondisi, fungsi, pemeliharaan dan pemanfaatan rata-rata adalah 84,5 persen. Dengan nilai efektivitas tersebut diketahui bahwa keseluruhan variabel kondisi perangkat, fungsi dan pemanfaatannya tidak mempengaruhi konektivitas.  *****The Indonesian government has a strong commitment in supporting the growth of e-commerce and Digital Economy in Indonesia to attain Indonesia’s vision by 2020 as the largest digital economy nation in Southeast Asia. Fundamentally, the national connectivity supports from central level to local level are needed, where one of them comes from Integrated Broadband Village program. This research determines the effectiveness of devices in the DBT program and its correlation to the connectivity, by using importance-performance analysis method and Chi-square statistical test. It is known from the result that the effectiveness of devices, including condition, function, maintenance, and utilization variables, achieves 84.5 percent on average. The value shows that all mentioned variables have insignificant correlations to the connectivity.

  7. 78 FR 41343 - Expanding Access to Broadband and Encouraging Innovation Through Establishment of an Air-Ground...

    Science.gov (United States)

    2013-07-10

    ... an air-ground mobile broadband service, would promote participation by businesses owned by minorities... applications for air-ground mobile broadband licenses. The Notice also proposes to require new air-ground...-ground mobile broadband licensees in the 14.0-14.5 GHz band must file a renewal application in...

  8. 78 FR 22198 - Connect America Fund; A National Broadband Plan for Our Future; Establishing Just and Reasonable...

    Science.gov (United States)

    2013-04-15

    ... eligible telecommunications carriers relating to five-year build-out plans and broadband network testing... eligible telecommunications carriers (ETCs) relating to five-year build-out plans and broadband network... of broadband service build-out is reasonable over the five-year time period. B. Network...

  9. 75 FR 26180 - Effects on Broadband Communications Networks of Damage To or Failure of Network Equipment or...

    Science.gov (United States)

    2010-05-11

    ... COMMISSION 47 CFR Chapter I Effects on Broadband Communications Networks of Damage To or Failure of Network... broadband communications networks and to explore potential measures to reduce network vulnerability to... rapidly increasing importance of wireline and wireless broadband communications networks to...

  10. Evolution and prospects cable networks for broadband services : A technical perspective of the European and specifically the Dutch cable networks

    NARCIS (Netherlands)

    Anonymous

    2012-01-01

    European cable networks have played an important role in the development of broadcast television and broadband services. The delivery of Gigabit broadband services is considered to be the next access network challenge in the development of broadband services. In this whitepaper we have studied and a

  11. Autonomous, continuously recording broadband seismic stations at high-latitude

    Science.gov (United States)

    Beaudoin, B.; Parker, T.; Bonnett, B.; Tytgat, G.; Anderson, K.; Fowler, J.

    2009-04-01

    IRIS PASSCAL is in the third year of an NSF funded development and acquisition effort to establish a pool of cold-hardened seismic stations specifically for high-latitude broadband deployments. We have two complete years of field trials and have successfully recorded continuous seismic data during both years with data recovery rates of ~90%. Our design is premised on a 2W autonomous system recording to local media, capable of lasting two years without service. The system is composed of four new design elements: a heavily insulated station enclosure; a state-of-health (SOH) Iridium modem; a light weight, easily deployed solar panel mount; and a power system that includes power switching between primary (Lithium Thionyl Chloride) and secondary batteries. The station enclosures have proved most critical in keeping our data acquisition systems operating within manufacturer specifications and primary batteries within a 50-70% efficiency range. Enclosures with 2.5cm-thick vacuum panels and 5cm of foam insulation have kept interior enclosure temperatures 25-30°C above background (typically below -50°C). This austral summer we are deploying version three of our enclosures. Significant changes in the design include thicker vacuum panels (5cm), more robust construction, and simplified cable routing. An important aspect of our station design is easy installation and minimal weight. To simplify installation our station enclosures are packed with datalogger, SOH communications and batteries in the lab or base camp, so that access to the internal components is not necessary at the remote site. Bulkhead connectors allow a user to fully interact with the system without ever having to open the enclosure. Solar panel mounts are also fully constructed prior to deployment. Once on site, digging two large holes (one for the enclosure and one for the broadband seismometer) and constructing the site takes roughly 2 hours. A station designed to record continuously for 12-14 months is

  12. Simulation of Broadband Time Histories Combining Deterministic and Stochastic Methodologies

    Science.gov (United States)

    Graves, R. W.; Pitarka, A.

    2003-12-01

    We present a methodology for generating broadband (0 - 10 Hz) ground motion time histories using a hybrid technique that combines a stochastic approach at high frequencies with a deterministic approach at low frequencies. Currently, the methodology is being developed for moderate and larger crustal earthquakes, although the technique can theoretically be applied to other classes of events as well. The broadband response is obtained by summing the separate responses in the time domain using matched butterworth filters centered at 1 Hz. We use a kinematic description of fault rupture, incorporating spatial heterogeneity in slip, rupture velocity and rise time by discretizing an extended finite-fault into a number of smaller subfaults. The stochastic approach sums the response for each subfault assuming a random phase, an omega-squared source spectrum and simplified Green's functions (Boore, 1983). Gross impedance effects are incorporated using quarter wavelength theory (Boore and Joyner, 1997) to bring the response to a generic baserock level (e.g., Vs = 1000 m/s). The deterministic approach sums the response for many point sources distributed across each subfault. Wave propagation is modeled using a 3D viscoelastic finite difference algorithm with the minimum shear wave velocity set at 620 m/s. Short- and mid-period amplification factors provided by Borcherdt (1994) are used to develop frequency dependent site amplification functions. The amplification functions are applied to the stochastic and determinsitic responses separately since these may have different (computational) reference site velocities. The site velocity is taken as the measured or estimated value of {Vs}30. The use of these amplification factors is attractive because they account for non-linear response by considering the input acceleration level. We note that although these design factors are strictly defined for response spectra, we have applied them to the Fourier amplitude spectra of our

  13. MOBB: Data Analysis from an Ocean Floor Broadband Seismic Observatory

    Science.gov (United States)

    Uhrhammer, R. A.; Dolenc, D.; Romanowicz, B.; Stakes, D.; McGill, P.; Neuhauser, D.; Ramirez, T.

    2003-12-01

    MOBB (Monterey bay Ocean floor Broad Band project) is a collaborative project between the Monterey Bay Aquarium Research Institute (MBARI) and the Berkeley Seismological Laboratory (BSL). Its goal is to install and operate a permanent seafloor broadband station as a first step towards extending the on-shore broadband seismic network in northern California, to the seaside of the North-America/Pacific plate boundary, providing improved azimuthal coverage for regional earthquake and structure studies. The MOBB station was installed on the seafloor in Monterey Bay, 40 km offshore, and at a depth of 1000m from the sea surface, in April 2002, and is completely buried under the seafloor level. The installation made use of MBARI's Point Lobos ship and ROV Ventana and the station currently records data autonomously. Dives are scheduled regularly (about every three months) to recover and replace the recording and battery packages. Some data were lost in the first half of 2003 due to hardware and software problems in the recording system. The ocean-bottom MOBB station currently comprises a three-component seismometer package (Guralp CMG-1T), a current-meter, a digital pressure gauge (DPG), and recording and battery packages. The seismometer package is mounted on a cylindrical titanium pressure vessel 54cm in height and 41 cm in diameter, custom built by the MBARI team and outfitted for underwater connection. Since the background noise in the near-shore ocean floor environment is high in the band pass of interest, for the study of regional and teleseismic signals, an important focus of this project is to develop methods to a posteriori increase signal to noise ratios, by deconvolving contributions from various sources of noise. We present results involving analysis of correlation of background noise with tide, ocean current and pressure records, combining data from MOBB and regional land based stations of the Berkeley Digital Seismic Network (BDSN). We also present preliminary

  14. Broadband sum frequency generation via chirped quasi-phase-matching

    CERN Document Server

    Rangelov, A A

    2011-01-01

    An efficient broadband sum frequency generation (SFG) technique using the two collinear optical parametric processes \\omega 3=\\omega 1+\\omega 2 and \\omega 4=\\omega 1+\\omega 3 is proposed. The technique uses chirped quasi-phase-matched gratings, which, in the undepleted pump approximation, make SFG analogous to adiabatic population transfer in three-state systems with crossing energies in quantum physics. If the local modulation period %for aperiodically poled quasi-phase-matching first makes the phase match occur for \\omega 3 and then for \\omega 4 SFG processes then the energy is converted adiabatically to the \\omega 4 field. Efficient SFG of the \\omega 4 field is also possible by the opposite direction of the local modulation sweep; then transient SFG of the \\omega 3 field is strongly reduced. Most of these features remain valid in the nonlinear regime of depleted pump.

  15. Broadband Macroscopic Cortical Oscillations Emerge from Intrinsic Neuronal Response Failures

    Directory of Open Access Journals (Sweden)

    Amir eGoldental

    2015-10-01

    Full Text Available Broadband spontaneous macroscopic neural oscillations are rhythmic cortical firing which was extensively examined during the last century, however, their possible origination is still controversial. In this work we show how macroscopic oscillations emerge in solely excitatory random networks and without topological constraints. We experimentally and theoretically show that these oscillations stem from the counterintuitive underlying mechanism - the intrinsic stochastic neuronal response failures. These neuronal response failures, which are characterized by short-term memory, lead to cooperation among neurons, resulting in sub- or several- Hertz macroscopic oscillations which coexist with high frequency gamma oscillations. A quantitative interplay between the statistical network properties and the emerging oscillations is supported by simulations of large networks based on single-neuron in-vitro experiments and a Langevin equation describing the network dynamics. Results call for the examination of these oscillations in the presence of inhibition and external drives.

  16. Broadband highly-efficient dielectric metadevices for polarization control

    CERN Document Server

    Kruk, Sergey; Kravchenko, Ivan; Miroshnichenko, Andrey; Neshev, Dragomir N; Kivshar, Yuri S

    2016-01-01

    Metadevices based on dielectric nanostructured surfaces with both electric and magnetic Mie-type resonances have resulted in the best efficiency to date for functional flat optics with only one disadvantage: narrow operational bandwidth. Here we experimentally demonstrate broadband transparent all-dielectric metasurfaces for highly efficient polarization manipulation. We utilize the generalized Huygens principle with a superposition of the scattering contributions from several electric and magnetic multipolar modes of the constituent meta-atoms to achieve destructive interference in reflection over a large spectral bandwidth. By employing this novel concept, we demonstrate reflectionless (~90% transmission) half-wave plates, quarter-wave plates, and vector beam q-plates that can operate across multiple telecom bands with ~99% polarization conversion efficiency.

  17. A Broadband Terahertz Waveguide T-Junction Variable Power Splitter

    Science.gov (United States)

    Reichel, Kimberly S.; Mendis, Rajind; Mittleman, Daniel M.

    2016-06-01

    In order for the promise of terahertz (THz) wireless communications to become a reality, many new devices need to be developed, such as those for routing THz waves. We demonstrate a power splitting router based on a parallel-plate waveguide (PPWG) T-junction excited by the TE1 waveguide mode. By integrating a small triangular septum into the waveguide plate, we are able to direct the THz light down either one of the two output channels with precise control over the ratio between waveguide outputs. We find good agreement between experiment and simulation in both amplitude and phase. We show that the ratio between waveguide outputs varies exponentially with septum translation offset and that nearly 100% transmission can be achieved. The splitter operates over almost the entire range in which the waveguide is single mode, providing a sensitive and broadband method for THz power splitting.

  18. Broadband excitation and collection in fiber-optic nonlinear endomicroscopy

    Science.gov (United States)

    Prakash Ghimire, Navin; Bao, Hongchun; Gu, Min

    2013-08-01

    Broadband excitation and collection in a fiber-optic nonlinear endomicroscope are realized by using a single hollow-core double-clad photonic crystal fiber and a gradient index lens. Femtosecond pulses with central wavelengths in the range of 750-850 nm can be directly delivered through the core of the fiber for nonlinear excitation without pre-chirping. A gradient index lens with numerical aperture 0.8 designed to operate over the near-infrared wavelength range is used for focusing the laser beam from the fiber for nonlinear excitation and for collecting the fluorescent signal from the sample. This compact system is suitable to perform nonlinear imaging of multiple fluorophors in the wavelength range of 750-850 nm.

  19. Performance measurement of broadband, wide-angle polarizing beam splitter

    Institute of Scientific and Technical Information of China (English)

    CHEN Wei-bin; ZHENG Zhen-rong; GU Pei-fu; ZHANG Yue-guang

    2007-01-01

    Polarizing beam splitter (PBS) is a critical optical component in projection display system because PBS performance greatly influences the contrast and brightness of the system. PBS performance is usually measured by spectrophotometer after coating and cementing, but the measured result cannot represent the actual performance in practice because people usually change the incident angle in one plane (horizontal plane) and do not consider the other plane (vertical plane). Geometrical polarization rotation occurring at reduced F-number influences the measuring precision of s-polarization transmittance (Ts) and p-polarization reflectance (Rp). A more accurate and practical way to measure the performance of broadband, wide-angle PBS is presented in this paper.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-05-15

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

  1. Broadband sample holder for microwave spectroscopy of superconducting qubits.

    Science.gov (United States)

    Averkin, A S; Karpov, A; Shulga, K; Glushkov, E; Abramov, N; Huebner, U; Il'ichev, E; Ustinov, A V

    2014-10-01

    We present a practical design and implementation of a broadband sample holder suitable for microwave experiments with superconducting integrated circuits at millikelvin temperatures. Proposed design can be easily integrated in standard dilution cryostats, has flat pass band response in a frequency range from 0 to 32 GHz, allowing the RF testing of the samples with substrate size up to 4 × 4 mm(2). The parasitic higher modes interference in the holder structure is analyzed and prevented via design considerations. The developed setup can be used for characterization of superconducting parametric amplifiers, bolometers, and qubits. We tested the designed sample holder by characterizing of a superconducting flux qubit at 20 mK temperature.

  2. Two-dimensional NQR using ultra-broadband electronics

    Science.gov (United States)

    Mandal, S.; Song, Y.-Q.

    2014-03-01

    We have recently developed an ultra-broadband instrument that can effectively excite and detect NMR and NQR signals over a wide frequency range. Our current system operates between 100 kHz and 3.2 MHz using an un-tuned sample coil. The major benefits of this instrument compared to conventional NQR/NMR systems include increased robustness, ease of use (in particular for multi-frequency experiments), and elimination of the need for tuning adjustments in the hardware. Here we describe its use for performing two-dimensional (2D) scans, which allow improved interpretation of complex NQR spectra by detecting the connected resonances. Our method relies on population transfers between the three energy levels of spin-1 nuclei (such as 14N) by using multi-frequency excitation and a single RF coil. Experimental results on pure samples and mixtures are also presented.

  3. A Method for Assessing Quality of Service in Broadband Networks

    DEFF Research Database (Denmark)

    Bujlow, Tomasz; Riaz, M. Tahir; Pedersen, Jens Myrup

    2012-01-01

    Monitoring of Quality of Service (QoS) in high-speed Internet infrastructure is a challenging task. However, precise assessments must take into account the fact that the requirements for the given quality level are service-dependent. Backbone QoS monitoring and analysis requires processing of large...... taken from the description of system sockets. This paper proposes a new method for measuring the Quality of Service (QoS) level in broadband networks, based on our Volunteer-Based System for collecting the training data, Machine Learning Algorithms for generating the classification rules and application...... and provide C5.0 high-quality training data, divided into groups corresponding to different types of applications. It was found that currently existing means of collecting data (classification by ports, Deep Packet Inspection, statistical classification, public data sources) are not sufficient and they do...

  4. HFC双向宽带网%HFC-way Broadband Network

    Institute of Scientific and Technical Information of China (English)

    刘前

    2015-01-01

    With the rapid advent of the information society, information exchange has already become the most important resource, it is mainly for the three forms of images, integrated, intelligent and personal, all-digital service support. HFC network is a better access network, the best solution is the information superhighway broadband access networks.%信息交换已然成最重要的资源,它主要表现为图像、声音和数据3种形式。信息网络发展方向是数字化、综合化、智能化和个人化,支持全数字化业务。HFC网是目前较好的接入网,是信息高速公路宽带接入网的最佳方案。

  5. Broadband dielectric response of AlN ceramic composites

    Directory of Open Access Journals (Sweden)

    Iryna V. Brodnikovska

    2014-03-01

    Full Text Available Aluminium nitride (AlN is considered as a substrate material for microelectronic applications. AlN ceramic composites with different amount of TiO2 (up to 4 vol.% were obtained using hot pressing at different sintering temperature from 1700 to 1900 °C. It was shown that milling of the raw AlN powder has strongly influence on sintering and improves densification. Broadband dielectric spectroscopy was used as a nondestructive method for monitoring of the ceramic microstructures. TiO2 additive affects the key properties of AlN ceramics. Thus, porosity of 0.1 %, dielectric permeability of σ = 9.7 and dielectric loss tangent of tanδ = 1.3·10-3 can be achieved if up to 2 vol.% TiO2 is added.

  6. Broadband metamaterial for nonresonant matching of acoustic waves.

    Science.gov (United States)

    D'Aguanno, G; Le, K Q; Trimm, R; Alù, A; Mattiucci, N; Mathias, A D; Aközbek, N; Bloemer, M J

    2012-01-01

    Unity transmittance at an interface between bulk media is quite common for polarized electromagnetic waves incident at the Brewster angle, but it is rarely observed for sound waves at any angle of incidence. In the following, we theoretically and experimentally demonstrate an acoustic metamaterial possessing a Brewster-like angle that is completely transparent to sound waves over an ultra-broadband frequency range with >100% bandwidth. The metamaterial, consisting of a hard metal with subwavelength apertures, provides a surface impedance matching mechanism that can be arbitrarily tailored to specific media. The nonresonant nature of the impedance matching effectively decouples the front and back surfaces of the metamaterial allowing one to independently tailor the acoustic impedance at each interface. On the contrary, traditional methods for acoustic impedance matching, for example in medical imaging, rely on resonant tunneling through a thin antireflection layer, which is inherently narrowband and angle specific.

  7. Broadband fractal acoustic metamaterials for low-frequency sound attenuation

    Science.gov (United States)

    Song, Gang Yong; Cheng, Qiang; Huang, Bei; Dong, Hui Yuan; Cui, Tie Jun

    2016-09-01

    We fabricate and experimentally characterize a broadband fractal acoustic metamaterial that can serve to attenuate the low-frequency sounds at selective frequencies ranging from 225 to 1175 Hz. The proposed metamaterials are constructed by the periodic Hilbert fractal elements made of photosensitive resin via 3D printing. In analogy to electromagnetic fractal structures, it is shown that multiple resonances can also be excited in the acoustic counterpart due to their self-similar properties, which help to attenuate the acoustic energy in a wide spectrum. The confinement of sound waves in such subwavelength element is evidenced by both numerical and experimental results. The proposed metamaterial may provide possible alternative for various applications such as the noise attenuation and the anechoic materials.

  8. A Broadband Terahertz Waveguide T-Junction Variable Power Splitter.

    Science.gov (United States)

    Reichel, Kimberly S; Mendis, Rajind; Mittleman, Daniel M

    2016-06-29

    In order for the promise of terahertz (THz) wireless communications to become a reality, many new devices need to be developed, such as those for routing THz waves. We demonstrate a power splitting router based on a parallel-plate waveguide (PPWG) T-junction excited by the TE1 waveguide mode. By integrating a small triangular septum into the waveguide plate, we are able to direct the THz light down either one of the two output channels with precise control over the ratio between waveguide outputs. We find good agreement between experiment and simulation in both amplitude and phase. We show that the ratio between waveguide outputs varies exponentially with septum translation offset and that nearly 100% transmission can be achieved. The splitter operates over almost the entire range in which the waveguide is single mode, providing a sensitive and broadband method for THz power splitting.

  9. Best-basis analysis of broadband tremor signals

    Directory of Open Access Journals (Sweden)

    P. Steffen

    1999-06-01

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

  10. Broadband lasercooling of relativistic ions at the ESR

    Energy Technology Data Exchange (ETDEWEB)

    Winters, Danyal; Ullmann, Johannes; Clark, Colin; Dimopoulou, Christina; Nolden, Fritz; Steck, Markus [GSI Darmstadt (Germany); Bussmann, Michael; Siebold, Mathias; Seltmann, Michael; Schramm, Ulrich [HZDR Dresden (Germany); Wen, Weiqiang [GSI Darmstadt (Germany); IMP CAS Lanzhou (China); Sanchez, Rodolfo; Lochmann, Matthias [GSI Darmstadt (Germany); Uni Mainz (Germany); Beck, Tobias; Rein, Benjamin; Tichelmann, Sascha; Birkl, Gerhard; Walther, Thomas [TU Darmstadt (Germany); Zhang, Dacheng; Yang, Jie; Ma, Xinwen [IMP CAS Lanzhou (China); Noertershaeuser, Wilfried [GSI Darmstadt (Germany); Uni Mainz (Germany); TU Darmstadt (Germany); Kuehl, Thomas [GSI Darmstadt (Germany); Uni Mainz (Germany); HI Jena (Germany); Stoehlker, Thomas [GSI Darmstadt (Germany); Uni Jena (Germany); HI Jena (Germany)

    2013-07-01

    We present new results on broadband laser cooling of stored relativistic C{sup 3+} ion beams at the ESR in Darmstadt. For the first time we could show laser cooling of bunched relativistic ion beams using a UV-laser which could scan over a very large range and thus cool all the ions in the 'bucket'. This scheme is much more versatile than a previous scheme, where the bunching frequency was scanned relative to a fixed laser frequency. We have also demonstrated that this cooling scheme works without pre-electron cooling, which is a prerequisite for its general application to future storage rings and synchrotrons, such as the HESR and the SIS100 at FAIR. We also present results from in vacuo VUV-fluorescence detectors, which have proven to be very effective.

  11. Automated computational aberration correction method for broadband interferometric imaging techniques.

    Science.gov (United States)

    Pande, Paritosh; Liu, Yuan-Zhi; South, Fredrick A; Boppart, Stephen A

    2016-07-15

    Numerical correction of optical aberrations provides an inexpensive and simpler alternative to the traditionally used hardware-based adaptive optics techniques. In this Letter, we present an automated computational aberration correction method for broadband interferometric imaging techniques. In the proposed method, the process of aberration correction is modeled as a filtering operation on the aberrant image using a phase filter in the Fourier domain. The phase filter is expressed as a linear combination of Zernike polynomials with unknown coefficients, which are estimated through an iterative optimization scheme based on maximizing an image sharpness metric. The method is validated on both simulated data and experimental data obtained from a tissue phantom, an ex vivo tissue sample, and an in vivo photoreceptor layer of the human retina.

  12. Synchronously pumped femtosecond optical parametric oscillator with broadband chirped mirrors

    Science.gov (United States)

    Stankevičiūte, Karolina; Melnikas, Simas; Kičas, Simonas; Trišauskas, Lukas; Vengelis, Julius; Grigonis, Rimantas; Vengris, Mikas; Sirutkaitis, Valdas

    2015-05-01

    We present results obtained during investigation of synchronously pumped optical parametric oscillator (SPOPO) with broadband complementary chirped mirror pairs (CMP). The SPOPO based on β-BBO nonlinear crystal is pumped by second harmonic of femtosecond Yb:KGW laser and provides signal pulses tunable over spectral range from 625 to 980 nm. More than 500 mW are generated in the signal beam, giving up to 27 % pump power to signal power conversion efficiency. The plane SPOPO cavity mirror pairs were specially designed to provide 99 % reflection in broad spectral range corresponding to signal wavelength tuning (630-1030 nm) and to suppress group delay dispersion (GDD) oscillations down to +/-10 fs2. Dispersion properties of designed mirrors were tested with white light interferometer (WLI) and attributed to the SPOPO tuning behaviour.

  13. The Australia Telescope Compact Array Broadband Backend (CABB)

    CERN Document Server

    Wilson, Warwick E; Axtens, P; Brown, A; Davis, E; Hampson, G; Leach, M; Roberts, P; Saunders, S; Koribalski, B S; Caswell, J L; Lenc, E; Stevens, J; Voronkov, M A; Wieringa, M H; Brooks, K; Edwards, P G; Ekers, R D; Emonts, B; Hindson, L; Johnston, S; Maddison, S T; Mahony, E K; Malu, S S; Massardi, M; Mao, M Y; McConnell, D; Norris, R P; Schnitzeler, D; Subrahmanyan, R; Urquhart, J S; Thompson, M A; Wark, R M

    2011-01-01

    Here we describe the Compact Array Broadband Backend (CABB) and present first results obtained with the upgraded Australia Telescope Compact Array (ATCA). The 16-fold increase in observing bandwidth, from 2 x 128 MHz to 2 x 2048 MHz, high bit sampling, and addition of 16 zoom windows (each divided into a further 2048 channels) provide major improvements for all ATCA observations. The benefits of the new system are: (1) hugely increased radio continuum and polarization sensitivity as well as image fidelity, (2) substantially improved capability to search for and map emission and absorption lines over large velocity ranges, (3) simultaneous multi-line and continuum observations, (4) increased sensitivity, survey speed and dynamic range due to high-bit sampling, and (5) high velocity resolution, while maintaining full polarization output. The new CABB system encourages all observers to make use of both spectral line and continuum data to achieve their full potential. Given the dramatic increase of the ATCA capab...

  14. Nanoscale tailored plasmonic material for optimum broadband solar harvesting

    Science.gov (United States)

    Zerulla, Dominic; McClean-Ilten, Éadaoin

    2016-09-01

    Is it possible to design a dedicated nanostructure on which all surface features contribute entirely to energy harvesting within a solar cell? This is an important challenge in the light that the efficiency of the solar cell technology utilised has a direct impact on the required land-use and also on reaching grid parity. Here, we take a unique approach and present an analytically derived optimum solution to the problem: a nanoscale metal topography, capable of significantly improving the efficiency of solid state solar cells via excitation of surface plasmon polaritons (SPPs). The presented structure is designed to achieve broadband excitation of SPPs through the highest possible density of desired k-vectors at the interface. This leads to high weighted absorption enhancements (>130%) and unprecedented improvements (>30%) of solar cell external quantum efficiencies over the entire harvestable range.

  15. Self-Organizing OFDMA System for Broadband Communication

    Science.gov (United States)

    Roy, Aloke (Inventor); Anandappan, Thanga (Inventor); Malve, Sharath Babu (Inventor)

    2016-01-01

    Systems and methods for a self-organizing OFDMA system for broadband communication are provided. In certain embodiments a communication node for a self organizing network comprises a communication interface configured to transmit data to and receive data from a plurality of nodes; and a processing unit configured to execute computer readable instructions. Further, computer readable instructions direct the processing unit to identify a sub-region within a cell, wherein the communication node is located in the sub-region; and transmit at least one data frame, wherein the data from the communication node is transmitted at a particular time and frequency as defined within the at least one data frame, where the time and frequency are associated with the sub-region.

  16. Broadband Meter-Wavelength Observations of Ionospheric Scintillation

    CERN Document Server

    Fallows, R A; McKay, D; Vierinen, J; Virtanen, I I; Postila, M; Ulich, Th; Enell, C-F; Kero, A; Iinatti, T; Lehtinen, M; Orispää, M; Raita, T; Roininen, L; Turunen, E; Brentjens, M; Ebbendorf, N; Gerbers, M; Grit, T; Gruppen, P; Meulman, H; Norden, M; de Reijer, J-P; Schoenmakers, A; Stuurwold, K

    2015-01-01

    Intensity scintillations of cosmic radio sources are used to study astrophysical plasmas like the ionosphere, the solar wind, and the interstellar medium. Normally these observations are relatively narrow band. With Low Frequency Array (LOFAR) technology at the Kilpisj\\"arvi Atmospheric Imaging Receiver Array (KAIRA) station in northern Finland we have observed scintillations over a 3 octave bandwidth. ``Parabolic arcs'', which were discovered in interstellar scintillations of pulsars, can provide precise estimates of the distance and velocity of the scattering plasma. Here we report the first observations of such arcs in the ionosphere and the first broad-band observations of arcs anywhere, raising hopes that study of the phenomenon may similarly improve the analysis of ionospheric scintillations. These observations were made of the strong natural radio source Cygnus-A and covered the entire 30-250\\,MHz band of KAIRA. Well-defined parabolic arcs were seen early in the observations, before transit, and disapp...

  17. Integrated Broadband Bowtie Antenna on Transparent Silica Substrate

    CERN Document Server

    Zhang, Xingyu; Wang, Shiyi; Subbaraman, Harish; Pan, Zeyu; Zhan, Qiwen; Chen, Ray T

    2016-01-01

    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 silica substrate. The bowtie antenna is designed with broad RF bandwidth to cover the X-band in the electromagnetic spectrum. We numerically investigate the antenna characteristics, specifically its resonant frequency and enhancement factor. Our designed bowtie antenna provides a strong broadband electric field enhancement in its feed gap. Taking advantage of the low-k silica substrate, high enhancement factor can be achieved without the unwanted reflection and scattering from the backside silicon handle which is the issue of using an SOI substrate. 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 silica substrates and then measuring their resonance frequencies. In addition, the far-field rad...

  18. Chirped photonic crystals: a natural strategy for broadband reflectance

    CERN Document Server

    Cook, Caleb Q

    2016-01-01

    One-dimensional photonic crystals with slowly varying, i.e. "chirped", lattice period are responsible for broadband light reflectance in many diverse biological contexts, ranging from the shiny coatings of various beetles to the eyes of certain butterflies. We present a quantum scattering analogy for light reflection from these adiabatically chirped photonic crystals (ACPCs) and apply a WKB-type approximation to obtain a closed-form expression for the reflectance. From this expression we infer several design principles, including a differential equation for the chirp pattern required to elicit a given reflectance spectrum and the minimal number of bilayers required to exceed a desired reflectance threshold. Comparison of the number of bilayers found in ACPCs throughout nature and our predicted minimal required number also gives a quantitative measure of the optimality of chirped biological reflectors. Together these results elucidate the design principles of chirped reflectors in nature and their possible app...

  19. Self-Powered Broadband Photodetector using Plasmonic Titanium Nitride.

    Science.gov (United States)

    Hussain, Amreen A; Sharma, Bikash; Barman, Tapan; Pal, Arup R

    2016-02-17

    We report the demonstration of plasmonic titanium nitride (TiN) for fabrication of an efficient hybrid photodetector. A novel synthesis method based on plasma nanotechnology is utilized for producing air stable plasma polymerized aniline-TiN (PPA-TiN) nanocomposite and its integration in photodetector geometry. The device performs as a self-powered detector that responds to ultraviolet and visible light at zero bias. The photodetector has the advantage of broadband absorption and outcomes an enhanced photoresponse including high responsivity and detectivity under low light conditions. This work opens up a new direction for plasmonic TiN-based hybrid nanocomposite and its exploitation in optoelectronic applications including imaging, light-wave communication and wire-free route for artificial vision.

  20. Optically implemented broadband blueshift switch in the terahertz regime.

    Science.gov (United States)

    Shen, Nian-Hai; Massaouti, Maria; Gokkavas, Mutlu; Manceau, Jean-Michel; Ozbay, Ekmel; Kafesaki, Maria; Koschny, Thomas; Tzortzakis, Stelios; Soukoulis, Costas M

    2011-01-21

    We experimentally demonstrate, for the first time, an optically implemented blueshift tunable metamaterial in the terahertz (THz) regime. The design implies two potential resonance states, and the photoconductive semiconductor (silicon) settled in the critical region plays the role of intermediary for switching the resonator from mode 1 to mode 2. The observed tuning range of the fabricated device is as high as 26% (from 0.76 THz to 0.96 THz) through optical control to silicon. The realization of broadband blueshift tunable metamaterial offers opportunities for achieving switchable metamaterials with simultaneous redshift and blueshift tunability and cascade tunable devices. Our experimental approach is compatible with semiconductor technologies and can be used for other applications in the THz regime.

  1. Broadband non-reciprocal transmission of sound with invariant frequency

    CERN Document Server

    Gu, Zhong-ming; Liang, Bin; Zou, Xin-ye; Cheng, Jian-chun

    2015-01-01

    The emergence of "acoustic diode" (AD) capable of rectifying acoustic wave like electrical diodes do to electricity has been believed to be able to offer unconventional manipulation on sound, e.g., to isolate the wrong-way reflection, and therefore have great potential in various important scenarios such as medical ultrasound applications. However, the existing ADs have always been suffering from the problem that the transmitted wave must have either doubled frequency or deviated direction, lacking the most crucial features for achieving such expectations in practice. Here we design and experimentally demonstrate a broadband yet compact non-reciprocal device with hitherto inaccessible functionality of maintaining the original frequency and high forward transmission while virtually blocking the backscattered wave, which is close to what a perfect AD is expected to provide and is promising to play the essential role in realistic acoustic systems like electric diodes do in electrical circuits. Such an extreme ab...

  2. Tailored quantum statistics from broadband states of light

    CERN Document Server

    Hartmann, S; Molitor, A; Reichert, M; Elsäßer, W; Walser, R

    2014-01-01

    We analyze the statistics of photons originating from amplified spontaneous emission generated by a quantum dot superluminescent diode. Experimentally detectable emission properties are taken into account by parametrizing the corresponding quantum state as a multi-mode phase-randomized Gaussian density operator. The validity of this model is proven in two subsequent experiments using fast two-photon-absorption detection observing second order equal-time- as well as second order fully time-resolved intensity correlations on femtosecond timescales. In the first experiment, we study the photon statistics when the number of contributing longitudinal modes is systematically reduced by applying well-controlled optical feedback. In a second experiment, we add coherent light from a single-mode laserdiode to quantum dot superluminescent diode broadband radiation. Tuning the power ratio, we realize tailored second order correlations ranging from Gaussian to Poissonian statistics. Both experiments are very well matched ...

  3. Broadband analog to digital conversion with spatial-spectral holography

    Energy Technology Data Exchange (ETDEWEB)

    Babbitt, W. Randall [Spectrum Lab, Montana State University, Bozeman, MT 59717-3510 (United States)]. E-mail: babbitt@physics.montana.edu; Neifeld, Mark A. [Spectrum Lab, Montana State University, Bozeman, MT 59717-3510 (United States); Merkel, Kristian D. [Spectrum Lab, Montana State University, Bozeman, MT 59717-3510 (United States)

    2007-11-15

    A new approach to broadband photonic-assisted analog-to-digital converter (ADC) technology is proposed and analyzed. The core of the device is a spatial spectral holographic (SSH) material, which can directly record the signals of interest in the frequency domain. An SSH-ADC acts as a frequency-domain stretch processor, which leverages the high performance of conventional ADCs by converting high bandwidth input signals to low bandwidth output signals without loss of information. Analysis of a 10 GHz bandwidth SSH-ADC predicts that 10-bit performance can be achieved with currently available materials and components. SSH-ADC technology is scalable to bandwidths over 100 GHz with recently developed SSH materials. While the SSH-ADC is a transient digitizer, the spatial parallelism of SSH materials can be utilized to enable continuous digitization.

  4. BROADBAND SPECTRAL INVESTIGATIONS OF SGR J1550-5418 BURSTS

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-09-01

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

  5. Telemedicina: a multimedia broadband teleradiology and radiosurgery project

    Science.gov (United States)

    de Blas-Garcia, Pedro; Lopez-Viver, Rodolfo; Martinez, Demetrio; Ruiz, Ignacio; Barriuso, Daniel; Janez-Escalada, Luis; Gomez, Jose L.; Luyando, Luis

    1996-05-01

    Telemedicina is a Spanish project that covers teleradiology and radiosurgery areas. This project is under the frame of the Spanish Broadband National Plan (PLANBA). The final technical tests are being ended over Ethernet and ATM and it is planned to get their first clinical results on February-96. Two pilots will be installed: one in Madrid linking two sites through a ATM network (provided by Telefonica, Spanish PTT) and a second one in Asturias (north of Spain) using ISDN primary access (2 Mbps). The system handles still images, voice and video records, scanned documents, text and slides allowing doctors to interchange this data using cooperative tools. The system is based on a multimedia Unix platform with voice, video and videoconference devices and boards. The platform will be used in several ways: as desktop videoconferencing, primary diagnosis and review. Communications are based on ATM (over AAL5) at 155 Mbps and ISDN (primary access). The protocol used in both networks is TCP/IP. The application is written in C++ (object oriented design and programming) and C. GUI is built under X-Windows and Motif. The codification of video is MJPEG done through dedicated hardware. The system is integrated in a small PACS (previously installed); the images are captured from the modalities such as CT using the DICOM standard and it is connected with the Radiological Information System. The application allows collaborative work: telepointer, shared windows, editors and actions. Main news of the Telemedicina project will be the incorporation of broadband networks (ATM at 155 Mbps) and the integration of collaborative work. This two aspects allow the doctors to improve their work speeding up the transmission and retrieval of medical records. Also this platform can be used to achieve several goals: such as primary diagnosis, videoconference, review.

  6. Broadband measurements of aerosol extinction in the ultraviolet spectral region

    Science.gov (United States)

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

    2013-04-01

    Aerosols influence the Earth's radiative budget by scattering and absorbing incoming solar radiation. The optical properties of aerosols vary as a function of wavelength, but few measurements have reported the wavelength dependence of aerosol extinction cross sections and complex refractive indices. We describe a new laboratory instrument to measure aerosol optical extinction as a function of wavelength, using cavity enhanced spectroscopy with a broadband light source. The instrument consists of two broadband channels which span the 360-390 and 385-420 nm spectral regions using two light emitting diodes (LED) and a grating spectrometer with charge-coupled device (CCD) detector. We determined aerosol extinction cross sections and directly observed Mie scattering resonances for aerosols that are purely scattering (polystyrene latex spheres and ammonium sulfate), slightly absorbing (Suwannee River fulvic acid), and strongly absorbing (nigrosin dye). We describe an approach for retrieving refractive indices as a function of wavelength from the measured extinction cross sections over the 360-420 nm wavelength region. The retrieved refractive indices for PSL and ammonium sulfate agree within uncertainty with the literature values for this spectral region. The refractive index determined for nigrosin is 1.78 (± 0.03) + 0.19 (± 0.08)i at 360 nm and 1.63 (± 0.03) + 0.21 (± 0.05)i at 420 nm. The refractive index determined for Suwannee River fulvic acid is 1.71 (± 0.02) + 0.07 (± 0.06)i at 360 nm and 1.66 (± 0.02) + 0.06 (± 0.04)i at 420 nm. These laboratory results support the potential for a field instrument capable of determining ambient aerosol optical extinction, average aerosol extinction cross section, and complex refractive index as a function of wavelength.

  7. Broadband enhanced graphene photodetector with fractal metasurface (Conference Presentation)

    Science.gov (United States)

    Wang, Di; Fang, Jieran; DeVault, Clayton T.; Chung, Ting-Fung; Chen, Yong P.; Boltasseva, Alexandra; Shalaev, Vladimir M.; Kildishev, Alexander V.

    2016-09-01

    Graphene has been demonstrated to be a promising photo-detection material because of its ultra-broadband absorption, compatibility with CMOS technology, and dynamic tunability. There are multiple known photo-detection mechanisms in graphene, among which the photovoltaic effect has the fastest response time thus is the prioritized candidate for ultrafast photodetector. There have been numerous efforts to enhance the intrinsically low sensitivity in graphene photovoltaic detectors using metallic plasmonic structures, but such plasmonic enhancements are mostly narrowband and polarization dependent. In this work, we propose a gold Cayley-tree fractal metasurface design that has a multi-band resonance, to realize broadband and polarization-insensitive plasmonic enhancement in graphene photovoltaic detectors. When illuminated with visible light, the fractal metasurface exhibits multiple hotspots at the metal-graphene interface, where the electric field of the incident electromagnetic wave is enhanced and contributes to generating excess electron-hole pairs in graphene. The large metal-graphene interface length in the fractal metasurface also helps to harvest at a higher efficiency the electron-hole pairs by built-in electric field due to metal-graphene potential gradient. To demonstrate the concept, we carried out experiment using Ar-Kr CW laser, an optical chopper, and lock-in amplifier. We obtained experimentally an almost constant ten-fold enhancement of photocurrent generated on the fractal metasurface compared to that generated on the plain gold-graphene edge, at all tested wavelengths (488 nm, 514 nm, 568 nm, and 647 nm). We also observed an unchanged photoresponse with respect to incident light polarization angles, which is a result of the highly symmetric geometry of the fractal metasurface.

  8. Broadband seismological observations at The Geysers geothermal area, California, USA

    Science.gov (United States)

    Jousset, Philippe; Gritto, Roland; Haberland, Christian; Hartline, Craig

    2013-04-01

    The understanding of structure and dynamics of geothermal reservoirs for geothermal exploration and sustainable use of the resource requires an assessment using a multidisciplinary approach. The Geysers geothermal reservoir in northern California is the largest producing geothermal field in the world and has been exploited for over 50 years. Among other geophysical surveys, numerous seismic studies have been conducted based on data acquired by the LBNL seismic monitoring network over the past 20 years. However, thus far, no continuous seismic data have been recorded at the Geysers, which prevents detailed continuous monitoring in relation to reservoir operation. In February 2012, we deployed a temporary network of 33 broadband seismic stations, including Guralp and Trillium sensors (0.008 - 100 Hz). At present the network is still in operation. Twenty-six stations are located within the perimeter of the geothermal reservoir, while 7 are located on a perimeter around the reservoir at greater distances. While the recordings of larger magnitude events (M>3.5) may be saturated on the local stations, the outer stations are intended to record these events without interruption. We present analyses of a larger magnitude event (M~3.5) as well as correlations of continuous observations to geothermal operations. Thanks to the high density of instrumentation and the high dynamic range of the broadband sensors, smaller events (microseismicity) can be detected more easily, allowing for better precision in locations and more accuracy in the determination of magnitudes. The increased dynamic range offers an important improvement in the analysis of seismicity as the majority of events at The Geysers have magnitudes of M<2.0.

  9. Broadband Spectral Investigations of SGR J1550-5418 Bursts

    Science.gov (United States)

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

    2012-01-01

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

  10. Free-space optics: broadband wireless supplement to fiber networks

    Science.gov (United States)

    Leitgeb, Erich; Bregenzer, Josef; Gebhart, M.; Fasser, Peter; Merdonig, A.

    2003-07-01

    Free Space Optics (FSO) is an excellent supplement to conventional radio links and fiber optics. It is the broadband wireless solution for closing the "Last Mile" connectivity gap throughout metropolitan networks. FSO is useful in dense urban and urban applications. The realiabilty and availability of the FSO-link is mainly determined by the local atmospheric condition. In this paper the results of the investigations of the research group "OptiKon" on different installed common network-architectures (ring, mesh and star) are presented. An "Optical Repeater" was used, if there was no line of sight between transmitter and receiver. The usage of optical free space propagation wthi Light Emitting Diodes are source instead of conventionally broadband transmission systems like optical fibers or radio links was also investigated at the Department of Communications and Wave Propagation. Using extended light sources like LEDs and/or multiple transmitter optics due to new laser safety regulations allows multiple output power within the same laser class, increasing the power link budget especially for short range FSO systems. In a first step two families of cost-effective systems were developed and realized. One is based on a modular concept using available standard components, allowing demonstrates at 2×10 Mbps data rae. Another is used for the larger distnaces of about 300 m at a specific power margin of 25 dB/km. Systems for higher data rate are under development. Additionally some ideas and their possible realization for point-to-multipoint configuration are considered. In the last chapter a short overivew about the main results of the work of "OptiKom" is discussed.

  11. Tunable Dielectric Materials and Devices for Broadband Wireless Communications

    Science.gov (United States)

    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

  12. Parallel Processing of Broad-Band PPM Signals

    Science.gov (United States)

    Gray, Andrew; Kang, Edward; Lay, Norman; Vilnrotter, Victor; Srinivasan, Meera; Lee, Clement

    2010-01-01

    A parallel-processing algorithm and a hardware architecture to implement the algorithm have been devised for timeslot synchronization in the reception of pulse-position-modulated (PPM) optical or radio signals. As in the cases of some prior algorithms and architectures for parallel, discrete-time, digital processing of signals other than PPM, an incoming broadband signal is divided into multiple parallel narrower-band signals by means of sub-sampling and filtering. The number of parallel streams is chosen so that the frequency content of the narrower-band signals is low enough to enable processing by relatively-low speed complementary metal oxide semiconductor (CMOS) electronic circuitry. The algorithm and architecture are intended to satisfy requirements for time-varying time-slot synchronization and post-detection filtering, with correction of timing errors independent of estimation of timing errors. They are also intended to afford flexibility for dynamic reconfiguration and upgrading. The architecture is implemented in a reconfigurable CMOS processor in the form of a field-programmable gate array. The algorithm and its hardware implementation incorporate three separate time-varying filter banks for three distinct functions: correction of sub-sample timing errors, post-detection filtering, and post-detection estimation of timing errors. The design of the filter bank for correction of timing errors, the method of estimating timing errors, and the design of a feedback-loop filter are governed by a host of parameters, the most critical one, with regard to processing very broadband signals with CMOS hardware, being the number of parallel streams (equivalently, the rate-reduction parameter).

  13. The Prediction of Broadband Shock-Associated Noise from Dualstream and Rectangular Jets Using RANS CFD

    Science.gov (United States)

    Miller, Steven A.; Morris, Philip J.

    2010-01-01

    Supersonic jets operating off-design produce broadband shock-associated noise. Broadband shock-associated noise is characterized by multiple broadband peaks in the far-field and is often the dominant source of noise towards the sideline and upstream direction relative to the jet axis. It is due to large scale coherent turbulence structures in the jet shear layers interacting with the shock cell structure. A broadband shock-associated noise model recently developed by the authors predicts this noise component from solutions to the Reynolds averaged Navier-Stokes equations using a two-equation turbulence model. The broadband shock-associated noise model is applied to dualstream and rectangular nozzles operating supersonically, heated, and off-design. The dualstream jet broadband shock-associated noise predictions are conducted for cases when the core jet is supersonic and the fan jet is subsonic, the core jet is subsonic and the fan jet is supersonic, and when both jet streams operate supersonically. Rectangular jet predictions are shown for a convergent-divergent nozzle operating both over- and under-expanded for cold and heated conditions. The original model implementation has been heavily modified to make accurate predictions for the dualstream jets. It is also argued that for over-expanded jets the oblique shock wave attached to the nozzle lip contributes little to broadband shock-associated noise. All predictions are compared with experiments.

  14. Running On-Demand Strong Ground Motion Simulations with the Second-Generation Broadband Platform

    Science.gov (United States)

    Callaghan, S.; Maechling, P. J.; Graves, R. W.; Somerville, P. G.; Collins, N.; Olsen, K. B.; Imperatori, W.; Jones, M.; Archuleta, R. J.; Schmedes, J.; Jordan, T. H.; Broadband Platform Working Group

    2010-12-01

    We have developed the second-generation Southern California Earthquake Center (SCEC) Broadband Platform by integrating scientific modeling codes into a system capable of computing broadband seismograms (0-10 Hz) for historical and scenario earthquakes in California. The SCEC Broadband Platform is a collaborative software development project involving SCEC researchers, graduate students, and the SCEC Community Modeling Environment (SCEC/CME) software development group. SCEC scientific groups have contributed software modules to the Broadband Platform including rupture generation, low-frequency deterministic seismogram synthesis, high-frequency stochastic seismogram synthesis, and non-linear site effects. These complex scientific codes have been integrated into a system that supports easy on-demand computation of broadband seismograms. The SCEC Broadband Platform is designed to be used by both scientific and engineering researchers familiar with ground motion simulations. Users may calculate broadband seismograms for both historical earthquakes (validation events including Northridge, Loma Prieta, and Landers) and user-defined earthquakes. Users may select among various codebases for rupture generation, low-frequency synthesis, high-frequency synthesis, and incorporation of site effects, with the option of running a goodness-of-fit comparison against observed or simulated seismograms. The platform produces a variety of data products, including broadband seismograms, rupture visualizations, and goodness-of-fit plots. The Broadband Platform was implemented using software development best practices that support software accuracy, reliability, and ease of use, including version control, user documentation, acceptance tests, and formal software releases. Users can install the platform on their own machine, verify that it is installed correctly, and run their own simulations on demand. The Broadband Platform enables users to run complex ground motion modeling codes without

  15. Security for Telecommuting and Broadband Communications: Recommendations of the National Institute of Standards and Technology

    Science.gov (United States)

    Kuhn, D. R.; Tracy, Miles C.; Frankel, Sheila E.

    2002-08-01

    This document is intended to assist those responsible - users, system administrators, and management - for telecommuting security, by providing introductory information about broadband communication security and policy, security of home office systems, and considerations for system administrators in the central office. It addresses concepts relating to the selection, deployment, and management of broadband communications for a telecommuting user. This document is not intended to provide a mandatory framework for telecommuting or home office broadband communication environments, but rather to present suggested approaches to the topic.

  16. Broadband nanophotonic wireless links and networks using on-chip integrated plasmonic antennas.

    Science.gov (United States)

    Yang, Yuanqing; Li, Qiang; Qiu, Min

    2016-01-19

    Owing to their high capacity and flexibility, broadband wireless communications have been widely employed in radio and microwave regimes, playing indispensable roles in our daily life. Their optical analogs, however, have not been demonstrated at the nanoscale. In this paper, by exploiting plasmonic nanoantennas, we demonstrate the complete design of broadband wireless links and networks in the realm of nanophotonics. With a 100-fold enhancement in power transfer superior to previous designs as well as an ultrawide bandwidth that covers the entire telecommunication wavelength range, such broadband nanolinks and networks are expected to pave the way for future optical integrated nanocircuits.

  17. Theory and design of broadband matching networks applied electricity and electronics

    CERN Document Server

    Chen, Wai-Kai

    1976-01-01

    Theory and Design of Broadband Matching Networks centers on the network theory and its applications to the design of broadband matching networks and amplifiers. Organized into five chapters, this book begins with a description of the foundation of network theory. Chapter 2 gives a fairly complete exposition of the scattering matrix associated with an n-port network. Chapter 3 considers the approximation problem along with a discussion of the approximating functions. Chapter 4 explains the Youla's theory of broadband matching by illustrating every phase of the theory with fully worked out examp

  18. Graded index and randomly oriented core-shell silicon nanowires for broadband and wide angle antireflection

    Directory of Open Access Journals (Sweden)

    P. Pignalosa

    2011-09-01

    Full Text Available Antireflection with broadband and wide angle properties is important for a wide range of applications on photovoltaic cells and display. The SiOx shell layer provides a natural antireflection from air to the Si core absorption layer. In this work, we have demonstrated the random core-shell silicon nanowires with both broadband (from 400nm to 900nm and wide angle (from normal incidence to 60º antireflection characteristics within AM1.5 solar spectrum. The graded index structure from the randomly oriented core-shell (Air/SiOx/Si nanowires may provide a potential avenue to realize a broadband and wide angle antireflection layer.

  19. Improving the solar zenith angle dependence of broadband UV radiometers calibration

    Directory of Open Access Journals (Sweden)

    M. L. Cancillo

    2007-12-01

    Full Text Available This paper focusses on the proposal of a new method for the calibration of broadband ultraviolet radiometers. The advantage of the method proposed is the accurate modelling of the dependence on the solar zenith angle. The new model is compared with other one-step calibration methods and with the two-step method, which requires the knowledge of the actual response of the broadband radiometer. For this purpose, three broadband radiometers are calibrated against a spectrophotometer of reference. The new method is validated comparing its predictions with the spectrophotometer measurements using an independent data set.

  20. Recording Tilt with Broadband Seismic Sensors at Erupting Volcanoes

    Science.gov (United States)

    Young, B. E.; Lees, J. M.; Lyons, J. J.

    2011-12-01

    The horizontal components of broadband seismometers are known to be susceptible to gravitational acceleration due to slow tilting, and this has been successfully exploited to assess ground deformation at many volcanoes, including Anatahan (Mariana Islands), Meakan-dake (Japan), Santiaguito (Guatemala) and Stromboli (Italy). Tilt can be estimated from seismic velocity by differentiating, scaling to remove gravity, and applying an instrument correction. The fundamental assumption in estimating tilt from broadband data is that the signal recorded is the result of tilt and not translation, thus analysis of tilt require filtering below corner frequencies of seismic instruments, where the response to tilt should be flat. However, processing techniques for deriving tilt are not uniform among researchers. Filter type and passband allowance for the processing of data sets differs from case to case, and the dominant periods of tilt signals may vary from tens to hundreds of seconds. For instance, data from Santiaguito was filtered in the 600-30s passband, while at Anatahan filters spanned 13 hours to 8 minutes. In our study, we investigate tilt from seismic data sets at Karymsky (Kamchatka, Russia), Fuego (Guatemala), Yasur (Vanuatu), and Tungurahua (Ecuador) to understand implementation and limitations of this tool. We examine the importance of filter-type distortion related to filtering on the seismic signal. For example, a comparison of time domain versus frequency domain implementation is explored using a variety of lowpass and bandpass filters. We also investigate the advantages and drawbacks of causal versus acausal filters. In a few cases tiltmeters have been co-located with broadband seismic sensors for direct comparison. Signals at Mt. St. Helens, Stromboli, Sakurajima, and Semeru show a correlation of tilt and seismic records, although records at Karymsky volcano suggest that no tilt is recorded on either instrument. We speculate that strong vent explosions exhibit

  1. Comparative Noise Performance of Portable Broadband Sensor Emplacements

    Science.gov (United States)

    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 (installations supported by the PASSCAL program was anecdotal. A formal comparison of these various installation techniques is the subject of this poster

  2. Optimal multisine excitation design for broadband electrical impedance spectroscopy

    Science.gov (United States)

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

    2011-11-01

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

  3. Broadband Phase Retrieval for Image-Based Wavefront Sensing

    Science.gov (United States)

    Dean, Bruce H.

    2007-01-01

    A focus-diverse phase-retrieval algorithm has been shown to perform adequately for the purpose of image-based wavefront sensing when (1) broadband light (typically spanning the visible spectrum) is used in forming the images by use of an optical system under test and (2) the assumption of monochromaticity is applied to the broadband image data. Heretofore, it had been assumed that in order to obtain adequate performance, it is necessary to use narrowband or monochromatic light. Some background information, including definitions of terms and a brief description of pertinent aspects of image-based phase retrieval, is prerequisite to a meaningful summary of the present development. Phase retrieval is a general term used in optics to denote estimation of optical imperfections or aberrations of an optical system under test. The term image-based wavefront sensing refers to a general class of algorithms that recover optical phase information, and phase-retrieval algorithms constitute a subset of this class. In phase retrieval, one utilizes the measured response of the optical system under test to produce a phase estimate. The optical response of the system is defined as the image of a point-source object, which could be a star or a laboratory point source. The phase-retrieval problem is characterized as image-based in the sense that a charge-coupled-device camera, preferably of scientific imaging quality, is used to collect image data where the optical system would normally form an image. In a variant of phase retrieval, denoted phase-diverse phase retrieval [which can include focus-diverse phase retrieval (in which various defocus planes are used)], an additional known aberration (or an equivalent diversity function) is superimposed as an aid in estimating unknown aberrations by use of an image-based wavefront-sensing algorithm. Image-based phase-retrieval differs from such other wavefront-sensing methods, such as interferometry, shearing interferometry, curvature

  4. Broadband Mid-Infrared Comb-Resolved Fourier Transform Spectroscopy

    Science.gov (United States)

    Lee, Kevin; Mills, Andrew; Mohr, Christian; Jiang, Jie; Fermann, Martin; Maslowski, Piotr

    2014-06-01

    We report on a comb-resolved, broadband, direct-comb spectroscopy system in the mid-IR and its application to the detection of trace gases and molecular line shape analysis. By coupling an optical parametric oscillator (OPO), a 100 m multipass cell, and a high-resolution Fourier transform spectrometer (FTS), sensitive, comb-resolved broadband spectroscopy of dilute gases is possible. The OPO has radiation output at 3.1-3.7 and 4.5-5.5 μm. The laser repetition rate is scanned to arbitrary values with 1 Hz accuracy around 417 MHz. The comb-resolved spectrum is produced with an absolute frequency axis depending only on the RF reference (in this case a GPS disciplined oscillator), stable to 1 part in 10^9. The minimum detectable absorption is 1.6x10-6 wn Hz-1/2. The operating range of the experimental setup enables access to strong fundamental transitions of numerous molecular species for applications based on trace gas detection such as environmental monitoring, industrial gas calibration or medical application of human breath analysis. In addition to these capabilities, we show the application for careful line shape analysis of argon-broadened CO band spectra around 4.7 μm. Fits of the obtained spectra clearly illustrate the discrepancy between the measured spectra and the Voigt profile (VP), indicating the need to include effects such as Dicke narrowing and the speed-dependence of the collisional width and shift in the line shape model, as was shown in previous cw-laser studies. In contrast to cw-laser based experiments, in this case the entire spectrum (˜ 250 wn) covering the whole P and R branches can be measured in 16 s with 417 MHz resolution, decreasing the acquisition time by orders of magnitude. The parallel acquisition allows collection of multiple lines simultaneously, removing the correlation of possible temperature and pressure drifts. While cw-systems are capable of measuring spectra with higher precision, this demonstration opens the door for fast

  5. High Temperature and High QE Broadband Longwave Infrared SLS FPA for LANDSAT Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose a high-performance broadband infrared focal plane array (FPA) for the Thermal Infrared Sensor (TIRS) on NASA's LANDSAT satellite. The FPA will feature a...

  6. 75 FR 26206 - Implementing the National Broadband Plan by Studying the Communications Requirements of Electric...

    Science.gov (United States)

    2010-05-11

    ... applications, including, but not limited to: fiber optic; microwave; copper lines; satellite; broadband wireless; unlicensed wireless mesh; licensed point-to-point and point-to- multipoint, low latency...

  7. Optimal design of laterally assembled hexagonal silicon nanowires for broadband absorption enhancement in ultrathin solar cells

    Science.gov (United States)

    Shahraki, Mojtaba; Salehi, Mohammad Reza; Abiri, Ebrahim

    2015-11-01

    Design approaches to carry out broadband absorption in laterally assembled hexagonal silicon nanowire (NW) solar cells are investigated. Two different methods are proposed to improve the current density of silicon NW solar cells. It is observed that the key to the broadband absorption is disorder and irregularity. The first approach to reach the broadband absorption is using multiple NWs with different geometries. Nevertheless, the maximum enhancement is obtained by introducing irregular NWs. They can support more cavity modes, while scattering by NWs leads to broadening of the absorption spectra. An array of optimized irregular NWs also has preferable features compared to other broadband structures. Using irregular NW arrays, it is possible to improve the absorption enhancement of solar cells without introducing more absorbing material.

  8. Zero-Loss Broadband Dispersion Compensation Scheme for G.652 Fibers

    Institute of Scientific and Technical Information of China (English)

    Kamna; Pande; M.R.; Shenoy; B.P.; Pal; K.Thyagarajan

    2003-01-01

    We have evaluated the gain characteristics of an erbium-doped broadband dual-core dispersion compensating fiber (DCF) to achieve a loss-less dispersion compensating module for long-haul G.652 fiber links.

  9. Combined MIMO adaptive and decentralized controllers for broadband active noise and vibration control

    NARCIS (Netherlands)

    Berkhoff, A.P.; Wesselink, J.M.

    2009-01-01

    Recent implementations of multiple-input multiple-output adaptive controllers for reduction of broadband noise and vibrations provide considerably improved performance over traditional adaptive algorithms. The most significant performance improvements are in terms of speed of convergence, the amount

  10. 77 FR 38533 - Lifeline and Link Up Reform and Modernization, Advancing Broadband Availability Through Digital...

    Science.gov (United States)

    2012-06-28

    ... and Link Up Reform and Modernization, Advancing Broadband Availability Through Digital Literacy... affiliates, and any branding (a ``dba,'' or ``doing-business-as company'' or brand designation) as well...

  11. Performance Analysis and Special Issues of Broadband Strategies in the Computer Communication

    CERN Document Server

    Ahamed, S S Riaz

    2010-01-01

    Broadband communications consists of the technologies and equipment required to deliver packet-based digital voice, video, and data services to end users. Broadband affords end users high-speed, always-on access to the Internet while affording service providers the ability to offer value-added services to increase revenues. Due to the growth of the Internet, there has been tremendous buildout of high-speed, inter-city communications links that connect population centers and Internet service providers (ISPs) points of presence (PoPs) around the world. This build out of the backbone infrastructure or core network has occurred primarily via optical transport technology. Broadband access technologies are being deployed to address the bandwidth bottleneck for the "last mile," the connection of homes and small businesses to this infrastructure. One important aspect of broadband access to the home is that it allows people to telecommute effectively by providing a similar environment as when they are physically prese...

  12. Multi-Criteria Comparison Between Legacy and Next Generation Point of Presence Broadband Network Architectures

    Directory of Open Access Journals (Sweden)

    Moufida Feknous

    Full Text Available Development of new applications and the introduction of innovative technologies can lead to revise network architectures in order to build sustainable broadband infrastructures. The present paper describes the main drivers and enabling technologies leadin ...

  13. 78 FR 54241 - Proposed Information Collection; Comment Request; BroadbandMatch Web Site Tool

    Science.gov (United States)

    2013-09-03

    ... of Collection BroadbandMatch users access the Web site through an Internet browser and voluntarily... Commerce, Room 6616, 14th and Constitution Avenue NW., Washington, DC 20230 (or via the Internet at...

  14. Structure Design of Polymer Electro-Optic Modulator with Ultra- Broadband

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Using finite element method, lots of calculating focusing on polymer electro-optic modulators with ultra-broadband were done, a few structures were analyzed. Coplanar waveguide electrode system was advanced, a few real examples was given.

  15. Highly Reflecting, Broadband Deformable Membrane Mirror for Wavefront Control Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Phase I STTR project will develop a highly reflecting, broadband, radiation resistant, low-stress and lightweight, membrane integrated into an electrostatically...

  16. A new broadband differential phase shifter fabricated using a novel CRLH structure

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Broadband phase shifters are mostly proposed and fabricated based on the scheme proposed by Shiffman, which uses a coupled line with far ends connected together and a uniform transmission line to give a differential phase shift. Based on the unique dispersion property of the composite right/left-handed (CRLH) metamaterial structure, a new configuration is presented in this paper for fabricating the broadband differential phase shifter, which employs a novel CRLH metamaterial structure as one of the differential phase-shift arms, instead of the conventional coupled line. The new circuit can achieve a phase shift of 90° in an operational bandwidth as broad as one octave and its phase deviations are quite small. An original design of the novel broadband phase shifter is presented, in which the artificial CRLH structure was implemented by microstrip quasi-lumped elements. Both the simulated and measured results of the 90° broadband differential phase shifter are presented.

  17. Broadband directional couplers fabricated in bulk glass with high repetition rate femtosecond laser pulses.

    Science.gov (United States)

    Chen, Wei-Jen; Eaton, Shane M; Zhang, Haibin; Herman, Peter R

    2008-07-21

    A femtosecond fiber laser was applied to fabricate broadband directional couplers inside bulk glass for general power splitting application in the 1250 to 1650-nm wavelength telecom spectrum. The broadband response was optimized over the 400-nm bandwidth by tailoring the coupling strength and the waveguide interaction length to balance the differing wavelength dependence of the straight interaction and bent transition regions. High spatial finesse of the femtosecond-laser writing technique enabled close placement (approxiamtely 6 microm) of adjacent waveguides that underpinned the wavelength-flattened broadband response at any coupling ratio in the 0% to 100% range. The spectral responses were well-represented by coupled mode theory, permitting simple design and implementation of broadband couplers for bulk 3D optical circuit integration.

  18. Broadband Wireline Provider Service: Other Copper Wireline; BBRI_otherCopper12

    Data.gov (United States)

    University of Rhode Island Geospatial Extension Program — This dataset represents the availability of wireline broadband Internet access in Rhode Island via "Other Copper Wireline" technology. In Rhode Island, this category...

  19. Ultra-Broadband Radial Polarization Conversion based on Goos-Hanchen Shift

    OpenAIRE

    Phua, P. B.; Lai, W. J.

    2007-01-01

    We demonstrate, for the first time, a scheme that generates radially-polarized light using Goos-Hanchen shift of a cylindrically symmetric Total Internal Reflection. It allows ultra-broadband radial polarization conversion for wavelengths differing >1 micron.

  20. 20 THz broadband generation using semi-insulating GaAs interdigitated photoconductive antennas.

    Science.gov (United States)

    Hale, P J; Madeo, J; Chin, C; Dhillon, S S; Mangeney, J; Tignon, J; Dani, K M

    2014-10-20

    We demonstrate broadband (20 THz), high electric field, terahertz generation using large area interdigitated antennas fabricated on semi-insulating GaAs. The bandwidth is characterized as a function of incident pulse duration (15-35 fs) and pump energy (2-30 nJ). Broadband spectroscopy of PTFE is shown. Numerical Drude-Lorentz simulations of the generated THz pulses are performed as a function of the excitation pulse duration, showing good agreement with the experimental data.

  1. Broadband terahertz generation using the semiconductor-metal transition in VO2

    Directory of Open Access Journals (Sweden)

    Nicholas A. Charipar

    2016-01-01

    Full Text Available We report the design, fabrication, and characterization of broadband terahertz emitters based on the semiconductor-metal transition in thin film VO2 (vanadium dioxide. With the appropriate geometry, picosecond electrical pulses are generated by illuminating 120 nm thick VO2 with 280 fs pulses from a femtosecond laser. These ultrafast electrical pulses are used to drive a simple dipole antenna, generating broadband terahertz radiation.

  2. Bistatic scattering characterization of a three-dimensional broadband cloaking structure

    CERN Document Server

    Alitalo, Pekka; Osipov, Andrey V; Thurner, Stefan; Kemptner, Erich; Tretyakov, Sergei A

    2011-01-01

    Here we present the results of full experimental characterization of broadband cloaking of a finite-sized metallic cylinder at X-band. The cloaking effect is characterized by measuring the bistatic scattering patterns of uncloaked and cloaked objects in free space and then comparing these with each other. The results of the measurements demonstrate a broadband cloaking effect and are in good agreement with numerical predictions.

  3. Broadband terahertz generation using the semiconductor-metal transition in VO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Charipar, Nicholas A., E-mail: nicholas.charipar@nrl.navy.mil; Kim, Heungsoo; Mathews, Scott A.; Piqué, Alberto [Naval Research Laboratory, 4555 Overlook Ave., SW, Washington, DC, 20375 (United States)

    2016-01-15

    We report the design, fabrication, and characterization of broadband terahertz emitters based on the semiconductor-metal transition in thin film VO{sub 2} (vanadium dioxide). With the appropriate geometry, picosecond electrical pulses are generated by illuminating 120 nm thick VO{sub 2} with 280 fs pulses from a femtosecond laser. These ultrafast electrical pulses are used to drive a simple dipole antenna, generating broadband terahertz radiation.

  4. The geographical digital divide in broadband access and governmental policies in Japan: three case studies

    Directory of Open Access Journals (Sweden)

    Yoshio Arai

    2013-06-01

    Full Text Available Broadband access is indispensable for advanced Internet services, because voluminous data transfers have recently become popular in developed societies. Although broadband access has spread to a certain degree in developed countries/regions, geographical gaps in broadband access (the so-called “geographical digital divide” remain. Based on three case studies in less-favoured areas of Japan (Hokkaido, Nagano Prefecture and Mie Prefecture, we examined how the geographical digital divide is being bridged, and the contributions that national and local government policies make to this process. Several implications were apparent. First, integrating communication infrastructures with manifold digital services, such as cable television services and broadband access, is an effective way to extend broadband to less-favoured areas. The Japanese government has promoted the construction of digital cable television networks, and they have played a significant role in the completion of universal broadband services. The challenge of digitizing terrestrial television broadcasting has been behind these policies. Another effective means of extending broadband has been the pressure exerted by local governments (under the national policy scheme on private cable television companies to bring their services to even the least populated regions. Finally, in those areas where private digital network services are unprofitable, the establishment of a publicly funded cable business (using a budget-transfer scheme, for example may be an effective option for extending broadband services. In general, the challenge of bridging the geographical digital divide should be tackled with a broad set of regional promotion policies for less-favoured regions.

  5. Secure communication in fiber optic systems via transmission of broad-band optical noise.

    Science.gov (United States)

    Buskila, O; Eyal, A; Shtaif, M

    2008-03-03

    We propose a new scheme for data encryption in the physical layer. Our scheme is based on the distribution of a broadband optical noise-like signal between Alice and Bob. The broadband signal is used for the establishment of a secret key that can be used for the secure transmission of information by using the one-time-pad method. We characterize the proposed scheme and study its applicability to the existing fiber-optics communications infrastructure.

  6. ACCORD Broadband ATM Satellite Experiment (BASE)-DS3 Ku-band channel

    Science.gov (United States)

    1997-12-01

    broadband ATM traf- fic. ATM was initially designed for fibre - optic media, i.e. a random error, low delay, and virtually error free channel...satellite links will soon be required to support broadband ATM traffic. ATM was initially designed for fibre - optic media, i.e. a random error, low...traffic generator and analyser. - Fibre Loop Converter: converts a DS-3 signal into a single-mode fibre optic signal and vice-versa. - EF Data Modem

  7. Role of public organisations in the creation of new broadband access infrastructures

    OpenAIRE

    2005-01-01

    Which roles may a public organisation play in the creation of new broadband access infrastructures? The main discussion issues about the roles of public organisations in relation to regulation and market distortion principles are given. Based upon some public policies and principles, the general requirements in making choices related to infrastructure in a specific broadband project are presented. The issues about the way how governments may fulfil the general requirements are presented. Exam...

  8. The Use of PLC Technology in Broadband Services Offered to Households

    Directory of Open Access Journals (Sweden)

    Daniel Adamko

    2012-04-01

    Full Text Available The volume and quality of broadband services in any country is being understood not only as a major parameter related to the economic growth of that country, but also as a major parameter how much that country is ready for economic growth in the near future. With this understanding the main reasons why expansion of broadband services in Slovakia is an urgent issue are briefly outlined in this paper.

  9. Broadband terahertz wave deflection based on C-shape complex metamaterials with phase discontinuities

    KAUST Repository

    Zhang, Xueqian

    2013-06-21

    A broadband terahertz wave deflector based on metasurface induced phase discontinuities is reported. Various frequency components ranging from 0.43 to 1.0 THz with polarization orthogonal to the incidence are deflected into a broad range of angles from 25° to 84°. A Fresnel zone plate consequently developed from the beam deflector is capable of focusing a broadband terahertz radiation. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Development of Broadband VLBI System and its Application to T&F Transfer

    Science.gov (United States)

    Sekido, Mamoru; Takefuji, Kazuhiro; Ujihara, Hideki; Kondo, Tetsuro; Tsutsumi, Masanori; Miyauchi, Yuka; Kawai, Eiji; Takiguchi, Hiroshi; Hasegawa, Shingo; Ichikawa, Ryuichi; Hanado, Yuko; Koyama, Yasuhiro; Watabe, Ken-ichi; Suzuyama, Tomonari; Amemiya, Masaki; Fukuzaki, Yoshihiro; Komuro, Jun-ichi; Terada, Kenjiro; Namba, Kunitaka; Takahashi, Rumi; Okamoto, Yoshihiro; Ikeda, Takatoshi; Aoki, Tetsuo

    2015-08-01

    We are developing a new broadband VLBI system, named GALA-V, for frequency comparison. Atomic time standards connected to transportable small antennas are compared via broadband VLBI observation with large diameter antenna. Disadvantages of small antenna in sensitivity is compensated (1) by ten times wider frequency range of observation and (2) by joint observation with large diameter antenna. NICT has originally developed broadband feed system (6.5-15GHz) for Kashima 34m radio telescope. The system development and performance evaluation of the Gala-V system are being conducted at NICT (Koganei)- NMIJ (Tsukuba) baseline, where both NICT and NMIJ are institutes of maintaining their UTC.The broadband GALA-V system is designed to be compatible with the VGOS (VLBI2010 Global Observing System), which is the next generation geodetic VLBI system promoted by the IVS. We have successfully made the first VLBI observation between the new Ishioka 13m VGOS antenna of GSI and Kashima 34m antenna. Additionally super broadband VLBI observation over 8GHz bandwidth, and coherent signal synthesis for quite high delay resolution were achieved for the first time in the world. This paper will report recent progress of the broadband system development and results of frequency comparison experiments with the GALA-V system.

  11. Comparison of broadband and hyperspectral thermal infrared imaging of buried threat objects

    Science.gov (United States)

    McFee, John E.; Achal, Steve B.; Diaz, Alejandra U.; Faust, Anthony A.

    2013-06-01

    Previous research by many groups has shown that broad-band thermal infrared (TIR) imagers can detect buried explosive threat devices, such as unexploded ordnance (UXO), landmines and improvised explosive devices (IEDs). Broad-band detection measures the apparent temperature - an average over the wave band of the product of the true soil surface temperature and the emissivity. Broad-band detection suffers from inconsistent performance (low signal, high clutter rates), due in part to diurnal variations, environmental and meteorological conditions, and soil surface effects. It has been suggested that hyperspectral TIR imaging might have improved performance since it can, in principle, allow extraction of the wavelength-dependent emissivity and the true soil surface temperature. This would allow the surface disturbance effects to be separated from the soil column (bulk) effects. A significant, and as yet unanswered, question is whether hyperspectral TIR images provide better detection capability (higher probability of detection and/or lower false alarm rate) than do broad-band thermal images. TIR hyperspectral image data of threat objects, buried and surface-laid in bare soil, were obtained in arid, desert-like conditions over full diurnal cycles for several days. Regions of interest containing threat objects and backgrounds were extracted throughout the time period. Simulated broad-band images were derived from the hyperspectral images. The diurnal variation of the images was studied. Hyperspectral was found to provide some advantage over broad-band imaging in detection of buried threat objects for the limited data set studied.

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

    Science.gov (United States)

    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.

  13. Photonics-based tunable and broadband radio frequency converter

    Science.gov (United States)

    Borges, Ramon Maia; Mazzer, Daniel; Rufino Marins, Tiago Reis; Sodré, Arismar Cerqueira

    2016-03-01

    This paper is regarding the concept and development of a photonics-based tunable and broadband radio frequency converter (PBRC). It employs an external modulation technique to generate and reconfigure its output frequency, a digital circuit to manage the modulators' bias voltages, and an optical interface for connecting it to optical-wireless networks based on radio-over-fiber technology. The proposed optoelectronic device performs photonics-based upconversion and downconversion as a function of the local oscillator frequency and modulators' bias points. Experimental results demonstrate a radiofrequency (RF) carrier conversion with spectral purity over the frequency range from 750 MHz to 6.0 GHz, as well as the integration of the photonics-based converter with an optical backhaul based on a 1.5-km single-mode fiber from a geographically distributed optical network. Low phase noise and distortion absence illustrate its applicability for convergent and reconfigurable optical wireless communications. A potential application relies on the use of PBRC in convergent optical wireless networks to dynamically provide RF carriers as a function of the telecom operator demand and radio propagation environment.

  14. Optimization of broadband omnidirectional antireflection coatings for solar cells

    CERN Document Server

    Guo, Xia; Li, Chong; Zhou, Hongyi; Lv, Benshun; Feng, Yajie; Wang, Huaqiang; Liu, Wuming

    2015-01-01

    Broadband and omnidirectional antireflection coating is a generally effective way to improve solar cell efficiency, because the destructive interference between the reflected and input waves could maximize transmission light in the absorption layer. Several theoretical calculations have been developed to optimize the anti-reflective coating to maximize the average transmittance. However, the solar irradiances of the clear sky spectral direct beam on a receiver plane at different positions and times are variable greatly. Here we report a new theoretical calculation of anti-reflective coating with incident quantum efficiency {\\eta}in as evaluation function for practical application. The two-layer and three-layer anti-reflective coatings are optimized over {\\lambda} = [300, 1100] nm and {\\theta} = [0{\\deg}, 90{\\deg}] for cities of Quito, Beijing and Moscow. The {\\eta}in of two-layer anti-reflective coating increases by 0.26%, 1.37% and 4.24% for these 3 cities, respectively, compared with that other theoretical ...

  15. Broadband Lg Attenuation Modeling in the Middle East

    Energy Technology Data Exchange (ETDEWEB)

    Pasyanos, M E; Matzel, E M; Walter, W R; Rodgers, A J

    2008-08-21

    We present a broadband tomographic model of Lg attenuation in the Middle East derived from source- and site-corrected amplitudes. Absolute amplitude measurements are made on hand-selected and carefully windowed seismograms for tens of stations and thousands of crustal earthquakes resulting in excellent coverage of the region. A conjugate gradient method is used to tomographically invert the amplitude dataset of over 8000 paths over a 45{sup o} x 40{sup o} region of the Middle East. We solve for Q variation, as well as site and source terms, for a wide range of frequencies ranging from 0.5-10 Hz. We have modified the standard attenuation tomography technique to more explicitly define the earthquake source expression in terms of the seismic moment. This facilitates the use of the model to predict the expected amplitudes of new events, an important consideration for earthquake hazard or explosion monitoring applications. The attenuation results have a strong correlation to tectonics. Shields have low attenuation, while tectonic regions have high attenuation, with the highest attenuation at 1 Hz is found in eastern Turkey. The results also compare favorably to other studies in the region made using Lg propagation efficiency, Lg/Pg amplitude ratios and two-station methods. We tomographically invert the amplitude measurements for each frequency independently. In doing so, it appears the frequency-dependence of attenuation is not compatible with the power law representation of Q(f), an assumption that is often made.

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

    CERN Document Server

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

    2010-01-01

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

  17. A Broadband Emission Model of Magnetar Wind Nebulae

    CERN Document Server

    Tanaka, Shuta J

    2016-01-01

    Angular momentum loss by the plasma wind is considered as a universal feature of isolated neutron stars including magnetars. The wind nebulae powered by magnetars allow us to compare the wind properties and the spin-evolution of magnetars with those of rotation-powered pulsars (RPPs). In this paper, we construct a broadband emission model of magnetar wind nebulae (MWNe). The model is similar to past studies of young pulsar wind nebulae (PWNe) around RPPs, but is modified for the application to MWNe that have far less observational information than the young PWNe. We apply the model to the MWN around the youngest ($\\sim$ 1kyr) magnetar 1E 1547.0-5408 that has the largest spin-down power $L_{\\rm spin}$ among all the magnetars. However, the MWN is faint because of low $L_{\\rm spin}$ of 1E 1547.0-5408 compared with the young RPPs. Since most of parameters are not well constrained only by an X-ray flux upper limit of the MWN, we adopt the model parameters from young PWN Kes 75 around PSR J1846-0258 that is a pecul...

  18. Transfer function of FBS-3A feedback broadband seismometer

    Institute of Scientific and Technical Information of China (English)

    刘庆伟; 庄灿涛; 刘慧宁

    2001-01-01

    FBS-3A feedback broadband seismometer has been widely utilized in observation networks up to now. There-fore, it is very important and practically meaningful for the application of this kind of sensor to fulfill some relative research work about its transfer function and for the analysis to the data recorded and the further devel-opment of the seismometer. In this paper, from the viewpoint of achieving its working principle, method of systematic analysis is applied to deduce the transfer functions, including both the transfer function for calibra-tion and that for measurement. Moreover, on the basis of that, the distribution of its zeroes and poles in a com-plex frequency domain is analyzed, which provides a convincing evidence to simplify this seismometer system from a high-order one to a two-order one. And the emulation of the frequency characteristics of FBS-3A is pre-sented in this paper. On the whole, the aim of this article is to do some theoretical work about the earthquake observation sensor, and also to introduce the method of making systematic analysis in a complex frequency domain to the research and the development of the seismometers.

  19. Multicarrier Block-Spread CDMA for Broadband Cellular Downlink

    Directory of Open Access Journals (Sweden)

    Leus Geert

    2004-01-01

    Full Text Available Effective suppression of multiuser interference (MUI and mitigation of frequency-selective fading effects within the complexity constraints of the mobile constitute major challenges for broadband cellular downlink transceiver design. Existing wideband direct-sequence (DS code division multiple access (CDMA transceivers suppress MUI statistically by restoring the orthogonality among users at the receiver. However, they call for receive diversity and multichannel equalization to improve the fading effects caused by deep channel fades. Relying on redundant block spreading and linear precoding, we design a so-called multicarrier block-spread- (MCBS-CDMA transceiver that preserves the orthogonality among users and guarantees symbol detection, regardless of the underlying frequency-selective fading channels. These properties allow for deterministic MUI elimination through low-complexity block despreading and enable full diversity gains, irrespective of the system load. Different options to perform equalization and decoding, either jointly or separately, strike the trade-off between performance and complexity. To improve the performance over multi-input multi-output (MIMO multipath fading channels, our MCBS-CDMA transceiver combines well with space-time block-coding (STBC techniques, to exploit both multiantenna and multipath diversity gains, irrespective of the system load. Simulation results demonstrate the superior performance of MCBS-CDMA compared to competing alternatives.

  20. Reconfigurable Signal Processing and Hardware Architecture for Broadband Wireless Communications

    Directory of Open Access Journals (Sweden)

    Liang Ying-Chang

    2005-01-01

    Full Text Available This paper proposes a broadband wireless transceiver which can be reconfigured to any type of cyclic-prefix (CP -based communication systems, including orthogonal frequency-division multiplexing (OFDM, single-carrier cyclic-prefix (SCCP system, multicarrier (MC code-division multiple access (MC-CDMA, MC direct-sequence CDMA (MC-DS-CDMA, CP-based CDMA (CP-CDMA, and CP-based direct-sequence CDMA (CP-DS-CDMA. A hardware platform is proposed and the reusable common blocks in such a transceiver are identified. The emphasis is on the equalizer design for mobile receivers. It is found that after block despreading operation, MC-DS-CDMA and CP-DS-CDMA have the same equalization blocks as OFDM and SCCP systems, respectively, therefore hardware and software sharing is possible for these systems. An attempt has also been made to map the functional reconfigurable transceiver onto the proposed hardware platform. The different functional entities which will be required to perform the reconfiguration and realize the transceiver are explained.

  1. Ultrathin planar broadband absorber through effective medium design

    Institute of Scientific and Technical Information of China (English)

    Dong Liu; Haitong Yu; Zhen Yang; Yuanyuan Duan

    2016-01-01

    Ultrathin planar absorbers hold promise in solar energy systems because they can reduce the material,fabrication,and system cost.Here,we present a general strategy of effective medium design to realize ultrathin planar broadband absorbers.The absorber consists of two ultrathin absorbing dielectrics to designan effective absorbing medium,a transparent layer,and metallic substrate.Compared with previous studies,this strategy provides another dimension of freedom to enhance optical absorption;therefore,destructive interference can be realized over a broad spectrum.To demonstrate the power and simplicity of this strategy,we both experimentally and theoretically characterized an absorber with 5-nm-thick Ge,10-nm-thick Ti,and 50-nm-thick SiO2 films coated on an Ag substrate fabricated using simple deposition methods.Absorptivity higher than 80% was achieved in 15-nm-thick (1/50 of the center wavelength) Ge and Ti films from 400 nm to near 1 μm.As an application example,we experimentally demonstrated that the absorber exhibited a normal solar absorptivity of 0.8 with a normal emittance of 0.1 at 500 ℃,thus demonstrating its potential in solar thermal systems.The effective medium design strategy is general and allows material versatility,suggesting possible applications in real-time optical manipulation using dynamic materials.

  2. A prism based magnifying hyperlens with broad-band imaging

    Science.gov (United States)

    Habib, Md. Samiul; Stefani, Alessio; Atakaramians, Shaghik; Fleming, Simon C.; Argyros, Alexander; Kuhlmey, Boris T.

    2017-03-01

    Magnification in metamaterial hyperlenses has been demonstrated using curved geometries or tapered devices, at frequencies ranging from the microwave to the ultraviolet spectrum. One of the main issues of such hyperlenses is the difficulty in manufacturing. In this letter, we numerically and experimentally study a wire medium prism as an imaging device at THz frequencies. We characterize the transmission of the image of two sub-wavelength apertures, observing that our device is capable of resolving the apertures and producing a two-fold magnified image at the output. The hyperlens shows strong frequency dependent artefacts, a priori limiting the use of the device for broad-band imaging. We identify the main source of image aberration as the reflections supported by the wire medium and also show that even the weaker reflections severely affect the imaging quality. In order to correct for the reflections, we devise a filtering technique equivalent to spatially variable time gating so that ultra-broad band imaging is achieved.

  3. Broadband access network reference models: a different prospective

    Science.gov (United States)

    Mostafa, Mohamed S.

    1996-11-01

    The current view of the fiber-based broadband access network is that it could basically be modeled into two target networks represented by the following architectures, the fiber to the curb, building, home (FTTC/B/H) -- also termed switched digital video (SDV) -- architecture, and the hybrid fiber coax (HFC) architecture. Both architectures support on-demand digital services. One way to distinguish between these two architectures is based on the digital modulation scheme. The SDV/FTTC architecture utilizes baseband digital modulation both in the fiber distribution and the point-to- point drop. Whereas, the HFC architecture is pass-band and utilizes digitally modulated (as well as analog modulated) subcarriers both on the fiber and the coax for distribution to customers. From a network modeling point of view, the distinction between these two architectures is fuzzy. A hybrid between the above two architectures represents other architectural advantages especially bandwidth utilization in the upstream direction. This paper describes this hybrid architecture and provides an evaluation of the different access network configuration scenarios based on an expanded version of the DAVIC reference models.

  4. Accelerated speckle imaging with the ATST visible broadband imager

    Science.gov (United States)

    Wöger, Friedrich; Ferayorni, Andrew

    2012-09-01

    The Advanced Technology Solar Telescope (ATST), a 4 meter class telescope for observations of the solar atmosphere currently in construction phase, will generate data at rates of the order of 10 TB/day with its state of the art instrumentation. The high-priority ATST Visible Broadband Imager (VBI) instrument alone will create two data streams with a bandwidth of 960 MB/s each. Because of the related data handling issues, these data will be post-processed with speckle interferometry algorithms in near-real time at the telescope using the cost-effective Graphics Processing Unit (GPU) technology that is supported by the ATST Data Handling System. In this contribution, we lay out the VBI-specific approach to its image processing pipeline, put this into the context of the underlying ATST Data Handling System infrastructure, and finally describe the details of how the algorithms were redesigned to exploit data parallelism in the speckle image reconstruction algorithms. An algorithm re-design is often required to efficiently speed up an application using GPU technology; we have chosen NVIDIA's CUDA language as basis for our implementation. We present our preliminary results of the algorithm performance using our test facilities, and base a conservative estimate on the requirements of a full system that could achieve near real-time performance at ATST on these results.

  5. Toward broadband electroacoustic resonators through optimized feedback control strategies

    Science.gov (United States)

    Boulandet, R.; Lissek, H.

    2014-09-01

    This paper presents a methodology for the design of broadband electroacoustic resonators for low-frequency room equalization. An electroacoustic resonator denotes a loudspeaker used as a membrane resonator, the acoustic impedance of which can be modified through proportional feedback control, to match a target impedance. However, such impedance matching only occurs over a limited bandwidth around resonance, which can limit its use for the low-frequency equalization of rooms, requiring an effective control at least up to the Schroeder frequency. Previous experiments have shown that impedance matching can be achieved over a range of a few octaves using a simple proportional control law. But there is still a limit to the feedback gain, beyond which the feedback-controlled loudspeaker becomes non-dissipative. This paper evaluates the benefits of using PID control and phase compensation techniques to improve the overall performance of the electroacoustic resonator. More specifically, it is shown that some adverse effects due to high-order dynamics in the moving-coil transducer can be mitigated. The corresponding control settings are also identified with equivalent electroacoustic resonator parameters, allowing a straightforward design of the controller. Experimental results using PID control and phase compensation are finally compared in terms of sound absorption performances. As a conclusion the overall performances of electroacoustic resonators for damping the modal resonances inside a duct are presented, along with general discussions on practical implementation and the extension to actual room modes damping.

  6. Global characterization of seismic noise with broadband seismometers

    CERN Document Server

    Coughlin, Michael William

    2012-01-01

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

  7. Multiple slow waves in metaporous layers for broadband sound absorption

    Science.gov (United States)

    Yang, Jieun; Lee, Joong Seok; Kim, Yoon Young

    2017-01-01

    Sound absorption for a broad frequency range requires sound dissipation. The mechanics of acoustic metamaterials for non-dissipative applications has been extensively studied, but sound absorption using dissipative porous metamaterials has been less explored because of the complexity resulting from the coupling of its dissipative mechanism and metamaterial behavior. We investigated broadband sound absorption by engineering dissipative metaporous layers, which absorb sound by the mechanism of multiple slow waves, and combined local and global resonance phenomena. A set of rigid partitions of varying lengths was elaborately inserted in a hard-backed porous layer of a finite thickness. An effective medium theory was used to explain the physics involved; high performance at a low-frequency range was found to be mainly due to the formation of global resonances caused by multiple slow waves over the thickness of the metaporous layer, while enhancement at a high-frequency range was attributed to the combined effects of the global resonances and the local resonances directly related to the sizes of the inserted partitions.

  8. Broadband dielectric spectroscopy of inhomogeneous and composite weak conductors

    Science.gov (United States)

    Petzelt, J.; Nuzhnyy, D.

    2016-08-01

    In this paper, we discuss broadband dielectric spectroscopy from mHz up to the infrared range mainly for materials with inhomogeneous weak conductivity, including conductor-dielectric nanocomposites. Our discussion is based on the effective medium approximation (EMA) and experiments modeled by this approach are reviewed. We discuss core-shell composites modeled by coated-spheres (Hashin-Shtrikman model) and normal composites with a possible percolation of the conductor component resulting in sharp or smeared percolation threshold of the DC conductivity and diverging static permittivity in the former case. The sharp percolation threshold is modeled by the Bruggeman EMA or by general EMA with arbitrary percolation threshold and arbitrary critical exponents of the DC conductivity and static permittivity. For the case of smeared percolation threshold in the case of complex topologies, we use the Lichtenecker model allowing for partial percolation of both the components. Finally, numerous papers reporting negative permittivity in weakly conducting materials are criticized and concluded to be due to spurious effects.

  9. Experimental Investigation of Broadband Vaned Helix Traveling-Wave Tube

    Science.gov (United States)

    Kim, Hae Jin; Jang, Lae Bong; Seo, Won Bum; Choi, Jin Joo

    2006-01-01

    A broadband helical traveling-wave-tube (TWT) amplifier for microwave power module (MPM) applications is designed using high frequency structure simulation (HFSS) and LMsuite code. The LMsuite, which is a one-dimensional nonlinear code, was utilized to predict the nonlinear, large-signal performance of the helical TWT. Simulations predict that an output power of 22.6 W is produced when an input power of 63.1 mW is injected at 10 GHz, corresponding to a saturated gain of 25.5 dB. The saturated bandwidth is predicted to be 6-17 GHz. Experiments on a fabricated TWT show that an output power of 18.7 W is produced when an input power of 42.6 mW is injected at 10 GHz, corresponding to a saturated gain of 26.4 dB. The saturated bandwidth is measured to be 6-16 GHz. AM/PM distortion is up to 6°/dB at a drive level 6 dB below the saturation input power. The third-order intermodulation distortion (IMD) ratio is -19 dBc at a 10 dB backoff from the P1 dB point when two-tone signals of 12 and 12.005 GHz are injected at equal amplitude.

  10. Multicarrier Block-Spread CDMA for Broadband Cellular Downlink

    Science.gov (United States)

    Petré, Frederik; Leus, Geert; Moonen, Marc; De Man, Hugo

    2004-12-01

    Effective suppression of multiuser interference (MUI) and mitigation of frequency-selective fading effects within the complexity constraints of the mobile constitute major challenges for broadband cellular downlink transceiver design. Existing wideband direct-sequence (DS) code division multiple access (CDMA) transceivers suppress MUI statistically by restoring the orthogonality among users at the receiver. However, they call for receive diversity and multichannel equalization to improve the fading effects caused by deep channel fades. Relying on redundant block spreading and linear precoding, we design a so-called multicarrier block-spread- (MCBS-)CDMA transceiver that preserves the orthogonality among users and guarantees symbol detection, regardless of the underlying frequency-selective fading channels. These properties allow for deterministic MUI elimination through low-complexity block despreading and enable full diversity gains, irrespective of the system load. Different options to perform equalization and decoding, either jointly or separately, strike the trade-off between performance and complexity. To improve the performance over multi-input multi-output (MIMO) multipath fading channels, our MCBS-CDMA transceiver combines well with space-time block-coding (STBC) techniques, to exploit both multiantenna and multipath diversity gains, irrespective of the system load. Simulation results demonstrate the superior performance of MCBS-CDMA compared to competing alternatives.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-05-10

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

  12. Speech recognition systems on the Cell Broadband Engine

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Y; Jones, H; Vaidya, S; Perrone, M; Tydlitat, B; Nanda, A

    2007-04-20

    In this paper we describe our design, implementation, and first results of a prototype connected-phoneme-based speech recognition system on the Cell Broadband Engine{trademark} (Cell/B.E.). Automatic speech recognition decodes speech samples into plain text (other representations are possible) and must process samples at real-time rates. Fortunately, the computational tasks involved in this pipeline are highly data-parallel and can receive significant hardware acceleration from vector-streaming architectures such as the Cell/B.E. Identifying and exploiting these parallelism opportunities is challenging, but also critical to improving system performance. We observed, from our initial performance timings, that a single Cell/B.E. processor can recognize speech from thousands of simultaneous voice channels in real time--a channel density that is orders-of-magnitude greater than the capacity of existing software speech recognizers based on CPUs (central processing units). This result emphasizes the potential for Cell/B.E.-based speech recognition and will likely lead to the future development of production speech systems using Cell/B.E. clusters.

  13. Broadband infrared imaging spectroscopy for standoff detection of trace explosives

    Science.gov (United States)

    Kendziora, Christopher A.; Furstenberg, Robert; Papantonakis, Michael; Nguyen, Viet; McGill, R. Andrew

    2016-05-01

    This manuscript describes advancements toward a mobile platform for standoff detection of trace explosives on relevant substrates using broadband infrared spectroscopic imaging. In conjunction with this, we are developing a technology for detection based on photo-thermal infrared (IR) imaging spectroscopy (PT-IRIS). PT-IRIS leverages one or more IR quantum cascade lasers (QCL), tuned to strong absorption bands in the analytes and directed to illuminate an area on a surface of interest. An IR focal plane array is used to image the surface thermal emission upon laser illumination. The PT-IRIS signal is processed as a hyperspectral image cube comprised of spatial, spectral and temporal dimensions as vectors within a detection algorithm. Here we describe methods to increase both sensitivity to trace explosives and selectivity between different analyte types by exploiting a broader spectral range than in previous configurations. Previously we demonstrated PT-IRIS at several meters of standoff distance indoors and in field tests, while operating the lasers below the infrared eye-safe intensity limit (100 mW/cm2). Sensitivity to explosive traces as small as a single 10 μm diameter particle (~1 ng) has been demonstrated.

  14. Broadband Circular Polarizers Constructed by Helix-like Chiral Metamaterials

    CERN Document Server

    Ji, Ruonan; Liu, Xingxing; Chen, Xiaoshuang; Lu, Wei

    2016-01-01

    In this paper, a kind of helix-like chiral metamaterial, which can be realized with multiple conventional lithography or electron beam lithographic techniques, is proposed to achieve broadband bianisotropic optical response analogous to helical metamaterial. On the basis of twisted metamaterial, via tailoring the relative orientation within the lattice, the anisotropy of arc 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 to 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 from 4.69 {\\mu}m to 8.98 {\\mu}m with an average extinction ratio of 6.9. And the transmittance for selective polarization is above 0.8 in the entire operation...

  15. Metro Access Convergence for Broadband Future Low Energy Consumption Networks

    Directory of Open Access Journals (Sweden)

    G. M.T. Beleffi

    2011-01-01

    Full Text Available Problem statement: In study the impact of the optical technologies and infrastructures on the reduction of the carbon footprint maintaining high level of broadband to the end user is discussed. Approach: Authors analyze the main energy consumers in Core, Metro and Access Networks as well as the topology and the performaces of the EU FP7 SARDANA Project, a long reach full optical metro access convergent network. This permit to have a clear and innovative view on the topic of the green networks comparing commercial and on the edge solutions for the critical access segment. Three scenarios have been assumed with different uplink bandwidths: unlimited uplink in the CO, limited uplink of 400 Gbit sec-1 and strong limitation of 100 Gbit sec-1. Additionally, three different sizes of the access network with 100, 1,000 and 10,000 subscribers connected to a single CO have been considered. Results: Increasing the number of users and reducing the uplink bandwidth, the difference in energy efficiency between TDM and PONs and P-t-P FTTH networks increases. Conclusion: Authors conclude that in general, a SARDANA like network provides very good energy efficiency for both limited and unlimited uplink and for small and large networks.

  16. Numerical simulation of broadband vortex terahertz beams propagation

    Science.gov (United States)

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

    2016-08-01

    Orbital angular momentum (OAM) represents new informational degree of freedom for data encoding and multiplexing in fiber and free-space communications. OAM-carrying beams (also called vortex beams) were successfully used to increase the capacity of optical, millimetre-wave and radio frequency communication systems. However, the investigation of the OAM potential for the new generation high-speed terahertz communications is also of interest due to the unlimited demand of higher capacity in telecommunications. Here we present a simulation-based study of the propagating in non-dispersive medium broadband terahertz vortex beams generated by a spiral phase plate (SPP). The algorithm based on scalar diffraction theory was used to obtain the spatial amplitude and phase distributions of the vortex beam in the frequency range from 0.1 to 3 THz at the distances 20-80 mm from the SPP. The simulation results show that the amplitude and phase distributions without unwanted modulation are presented in the wavelengths ranges with centres on the wavelengths which are multiple to the SPP optical thickness. This fact may allow to create the high-capacity near-field communication link which combines OAM and wavelength-division multiplexing.

  17. Plasma wakefields driven by intense, broadband, incoherent electromagnetic radiation

    CERN Document Server

    Trines, R M G M; Mendonça, J T; Mori, W B; Norreys, P A; Bingham, R

    2014-01-01

    Non-linear wave-driven processes in plasmas are normally described by either a monochromatic pump wave that couples to other monochromatic waves, or as a random phase wave coupling to other random phase waves. An alternative approach involves an incoherent, random or broadband pump coupling to monochromatic and/or coherent structures in the plasma. This approach can be implemented through the wave kinetic model. In this model, the incoming pump wave is described by either a bunch (for coherent waves) or a sea (for random phase waves) of quasi-particles. A particle-in-cell type code has been developed to perform numerical simulations of such interactions using the quasi-particle approach. This code allows for a comparatively easy description of both random phase and coherent pump pulses coupling to slow electrostatic plasma waves, while providing an extended range of powerful diagnostics leading to a deeper physical insight into the dynamics of the fast waves. As an example, the propagation of short, intense l...

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

    Science.gov (United States)

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

    2016-09-01

    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.

  19. Nonperiodic metallic gratings transparent for broadband terahertz waves

    Science.gov (United States)

    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).

  20. A broadband two axis flux-gate magnetometer

    Directory of Open Access Journals (Sweden)

    P. Palangio

    1998-06-01

    Full Text Available A broadband two axis flux-gate magnetometer was developed to obtain high sensitivity in magnetotelluric measurements. In magnetotelluric sounding, natural low frequency electromagnetic fields are used to estimate the conductivity of the Earth's interior. Because variations in the natural magnetic field have small amplitude(10-100 pT in the frequency range 1 Hz to 100 Hz, highly sensitive magnetic sensors are required. In magnetotelluric measurements two long and heavy solenoids, which must be installed, in the field station, perpendicular to each other (north-south and east-west and levelled in the horizontal plane are used. The coil is a critical component in magnetotelluric measurements because very slight motions create noise voltages, particularly troublesome in wooded areas; generally the installation takes place in a shallow trench. Moreover the coil records the derivative of the variations rather than the magnetic field variations, consequently the transfer function (amplitude and phase of this sensor is not constant throughout the frequency range 0.001-100 Hz. The instrument, developed at L'Aquila Geomagnetic Observatory, has a flat response in both amplitude and phase in the frequency band DC-100 Hz, in addition it has low weight, low power, small volume and it is easier to install in the field than induction magnetometers. The sensivity of this magnetometer is 10 pT rms.

  1. Broadband sonar considerations for small underwater vehicle applications

    Science.gov (United States)

    Benjamin, Kim C.

    2003-10-01

    As underwater vehicles become more prevalent, so too does the design and integration of compact broadband sonar arrays. Rather than rely on conventional tonpilz technology, where the bandwidth is governed by the width of the transducer's mechanical resonance, designers must consider other transducer technologies that are better suited to small vehicle packaging constraints. These constraints include operational ruggedness, light weight, conformability, and low cost. This talk advocates the use of 1-3 piezocomposite and discusses the rationale behind such a selection. In going to a wideband material such as a 1-3 piezocomposite, with typical mechanical quality factors (Qm) around 2, the selection of where to place the resonance frequency differs from that of its tonpilz counterpart. For the tonpilz array, the sonar operational bandwidth is totally governed by the resonance response of the array element and is typically limited to approximately its 3-dB or half power points. Relaxor-based ferroelectric materials such as single crystal PMN-PT, which exhibit extremely large electromechanical coupling coefficients, cannot attain 3-dB bandwidths of a decade or more when configured in a tonpilz design. This presentation will discuss a 1-3 piezocomposite-based approach that places mechanical resonance near the upper band edge of an operational bandwidth of 1 decade (10-100 kHz).

  2. Safety management of Ethernet broadband access based on VLAN aggregation

    Science.gov (United States)

    Wang, Li

    2004-04-01

    With broadband access network development, the Ethernet technology is more and more applied access network now. It is different from the private network -LAN. The differences lie in four points: customer management, safety management, service management and count-fee management. This paper mainly discusses the safety management related questions. Safety management means that the access network must secure the customer data safety, isolate the broad message which brings the customer private information, such as ARP, DHCP, and protect key equipment from attack. Virtue LAN (VLAN) technology can restrict network broadcast flow. We can config each customer port with a VLAN, so each customer is isolated with others. The IP address bound with VLAN ID can be routed rightly. But this technology brings another question: IP address shortage. VLAN aggregation technology can solve this problem well. Such a mechanism provides several advantages over traditional IPv4 addressing architectures employed in large switched LANs today. With VLAN aggregation technology, we introduce the notion of sub-VLANs and super-VLANs, a much more optimal approach to IP addressing can be realized. This paper will expatiate the VLAN aggregation model and its implementation in Ethernet access network. It is obvious that the customers in different sub-VLANs can not communication to each other because the ARP packet is isolated. Proxy ARP can enable the communication among them. This paper will also expatiate the proxy ARP model and its implementation in Ethernet access network.

  3. Broadband measuring system for unsteady flow investigation in wind tunnel

    Science.gov (United States)

    Biriukov, V. I.; Garifullin, M. F.; Korneeva, D. B.; Slitinskaya, A. Ju.

    2016-10-01

    Due to increasingly tough requirements to the accuracy and informativity of the wind tunnel experiments, the urgency has grown of the unsteady flows research. A distinctive feature of such studies is synchronous multichannel measurements of rapidly changing in time process parameters (with a broadband spectrum and characteristic frequencies of 0 Hz to 1000 Hz and above) and also the need for fast processing and storage of large volumes of the data received. To solve these problems and to meet the requirements, TsAGI has developed a measuring system (MS) and the corresponding software. The basic purpose of MS is to conduct transonic buffeting research in T-128 wind tunnel. Besides, it can be used to study separated flow regimes, aeroelastic vibrations, including: classic flutter, stall flutter, limit cycle oscillations, etc. The MS can be used also to study a variety of transient regimes. It is possible to expand the system further on to enhance its performance without introducing any fundamental changes in its structure and software, and without breaking its operability for the period of modernization.

  4. A Hamiltonian method for finding broadband modal eigenvalues.

    Science.gov (United States)

    Wang, Haozhong; Wang, Ning; Gao, Dazhi

    2012-02-01

    For shallow water waveguides over a layered elastic bottom, modal eigenvalues can be determined by searching the locations in the complex plane of the horizontal wave number at which the complex phase function is a multiple of π [C. T. Tindle and N. R. Chapman, J. Acoust. Soc. Am. 96, 1777-1782 (1994)]. In this paper, a Hamiltonian method is introduced for tracing the path in the complex plane along which the phase function keeps real. The Hamiltonian method can also be extended to compute the broadband modal eigenvalues or the modal dispersion curves in the Pekeris waveguide with fluid/elastic bottoms. For each proper or leaky normal mode, a different Hamiltonian is constructed in the complex plane and used to trace automatically the complex dispersion curve with the eigenvalue in a reference frequency as the initial value. In contrast to the usual methods, the dispersion curve for each mode is determined individually. The Hamiltonian method shows good performance by comparing with KRAKEN.

  5. Laterally assembled nanowires for ultrathin broadband solar absorbers.

    Science.gov (United States)

    Song, Kyung-Deok; Kempa, Thomas J; Park, Hong-Gyu; Kim, Sun-Kyung

    2014-05-05

    We studied optical resonances in laterally oriented Si nanowire arrays by conducting finite-difference time-domain simulations. Localized Fabry-Perot and whispering-gallery modes are supported within the cross section of each nanowire in the array and result in broadband light absorption. Comparison of a nanowire array with a single nanowire shows that the current density (J(SC)) is preserved for a range of nanowire morphologies. The J(SC) of a nanowire array depends on the spacing of its constituent nanowires, which indicates that both diffraction and optical antenna effects contribute to light absorption. Furthermore, a vertically stacked nanowire array exhibits significantly enhanced light absorption because of the emergence of coupled cavity-waveguide modes and the mitigation of a screening effect. With the assumption of unity internal quantum efficiency, the J(SC) of an 800-nm-thick cross-stacked nanowire array is 14.0 mA/cm², which yields a ~60% enhancement compared with an equivalent bulk film absorber. These numerical results underpin a rational design strategy for ultrathin solar absorbers based on assembled nanowire cavities.

  6. Broadband PLC for Clustered Advanced Metering Infrastructure (AMI Architecture

    Directory of Open Access Journals (Sweden)

    Augustine Ikpehai

    2016-07-01

    Full Text Available Advanced metering infrastructure (AMI subsystems monitor and control energy distribution through exchange of information between smart meters and utility networks. A key challenge is how to select a cost-effective communication system without compromising the performance of the applications. Current communication technologies were developed for conventional data networks with different requirements. It is therefore necessary to investigate how much of existing communication technologies can be retrofitted into the new energy infrastructure to cost-effectively deliver acceptable level of service. This paper investigates broadband power line communications (BPLC as a backhaul solution in AMI. By applying the disparate traffic characteristics of selected AMI applications, the network performance is evaluated. This study also examines the communication network response to changes in application configurations in terms of packet sizes. In each case, the network is stress-tested and performance is assessed against acceptable thresholds documented in the literature. Results show that, like every other communication technology, BPLC has certain limitations; however, with some modifications in the network topology, it indeed can fulfill most AMI traffic requirements for flexible and time-bounded applications. These opportunities, if tapped, can significantly improve fiscal and operational efficiencies in AMI services. Simulation results also reveal that BPLC as a backhaul can support flat and clustered AMI structures with cluster size ranging from 1 to 150 smart meters.

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

    Science.gov (United States)

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

    2016-01-01

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

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

    Science.gov (United States)

    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.

  9. Broadband dielectric microwave microscopy on micron length scales.

    Science.gov (United States)

    Tselev, Alexander; Anlage, Steven M; Ma, Zhengkun; Melngailis, John

    2007-04-01

    We demonstrate that a near-field microwave microscope based on a transmission line resonator allows imaging in a substantially wide range of frequencies, so that the microscope properties approach those of a spatially resolved impedance analyzer. In the case of an electric probe, the broadband imaging can be used in a direct fashion to separate contributions from capacitive and resistive properties of a sample at length scales on the order of one micron. Using a microwave near-field microscope based on a transmission line resonator we imaged the local dielectric properties of a focused ion beam milled structure on a high-dielectric-constant Ba(0.6)Sr(0.4)TiO(3) thin film in the frequency range from 1.3 to 17.4 GHz. The electrostatic approximation breaks down already at frequencies above approximately 10 GHz for the probe geometry used, and a full-wave analysis is necessary to obtain qualitative information from the images.

  10. Locating Local Earthquakes Using Single 3-Component Broadband Seismological Data

    Science.gov (United States)

    Das, S. B.; Mitra, S.

    2015-12-01

    We devised a technique to locate local earthquakes using single 3-component broadband seismograph and analyze the factors governing the accuracy of our result. The need for devising such a technique arises in regions of sparse seismic network. In state-of-the-art location algorithms, a minimum of three station recordings are required for obtaining well resolved locations. However, the problem arises when an event is recorded by less than three stations. This may be because of the following reasons: (a) down time of stations in a sparse network; (b) geographically isolated regions with limited logistic support to setup large network; (c) regions of insufficient economy for financing multi-station network and (d) poor signal-to-noise ratio for smaller events at most stations, except the one in its closest vicinity. Our technique provides a workable solution to the above problematic scenarios. However, our methodology is strongly dependent on the velocity model of the region. Our method uses a three step processing: (a) ascertain the back-azimuth of the event from the P-wave particle motion recorded on the horizontal components; (b) estimate the hypocentral distance using the S-P time; and (c) ascertain the emergent angle from the vertical and radial components. Once this is obtained, one can ray-trace through the 1-D velocity model to estimate the hypocentral location. We test our method on synthetic data, which produces results with 99% precision. With observed data, the accuracy of our results are very encouraging. The precision of our results depend on the signal-to-noise ratio (SNR) and choice of the right band-pass filter to isolate the P-wave signal. We used our method on minor aftershocks (3 < mb < 4) of the 2011 Sikkim earthquake using data from the Sikkim Himalayan network. Location of these events highlight the transverse strike-slip structure within the Indian plate, which was observed from source mechanism study of the mainshock and larger aftershocks.

  11. Enantiomer Identification in Chiral Mixtures with Broadband Microwave Spectroscopy

    Science.gov (United States)

    Shubert, V. Alvin; Schmitz, David; Medcraft, Chris; Patterson, David; Doyle, John M.; Schnell, Melanie

    2014-06-01

    In nature and as products of chemical syntheses, chiral molecules often exist in mixtures with other chiral molecules. The analysis of these complex mixtures to identify the components, determine which enantiomers are present, and to measure the enantiomeric excesses (ee) is still one of the challenging but very important tasks of analytical chemistry. These analyses are required at every step of modern drug development, from candidate searches to production and regulation. We present here a new method of identifying individual enantiomers in mixtures of chiral molecules in the gas phase. It is based on broadband rotational spectroscopy and employs a sum or difference frequency generation three-wave mixing process that involves a closed cycle of three rotational transitions. The phase of the acquired signal bares the signature of the enantiomer (see figure), as it depends upon the combined quantity, μaμbμc, which is of opposite sign between members of an enantiomeric pair. Furthermore, because the signal amplitude is proportional to the ee, this technique allows for both determining which enantiomer is in excess and by how much. The high resolution of our technique allows us to perform molecule specific measurements of mixtures of chiral molecules with μaμbμc ≠ 0, even when the molecules are very similar (e.g. conformational isomers). We introduce the technique and present results on the analysis of mixtures of the terpenes, carvone, menthone, and carvomenthenol. D. Patterson, M. Schnell, J. M. Doyle, Nature. 497, 475-477, 2013 V. A. Shubert, D. Schmitz, D. Patterson, J. M. Doyle, M. Schnell, Ang. Chem. Int. Ed. 53, 1152-1155,2014

  12. A Broadband Emission Model of Magnetar Wind Nebulae

    Science.gov (United States)

    Tanaka, Shuta J.

    2016-08-01

    Angular momentum loss by the plasma wind is considered as a universal feature of isolated neutron stars including magnetars. The wind nebulae that are powered by magnetars allow us to compare the wind properties and the spin evolution of magnetars with those of rotation-powered pulsars (RPPs). In this paper, we construct a broadband emission model of magnetar wind nebulae (MWNe). This model is similar to past studies of young pulsar wind nebulae (PWNe) around RPPs, but is modified for the application to MWNe that have far less observational information than the young PWNe. We apply the model to the MWN around the youngest (˜1 kyr) magnetar, 1E 1547.0-5408, which has the largest spin-down power L spin among all the magnetars. However, the MWN is faint because of the low L spin of 1E 1547.0-5408 when compared to the young RPPs. Since most parameters are not well constrained by only an X-ray flux upper limit of the MWN, we adopt the model’s parameters from the young PWN Kes 75 around PSR J1846-0258, which is a peculiar RPP showing magnetar-like behaviors. The model predicts that γ-ray flux will be detected in a future TeV γ-ray observation by CTA (Cherenkov Telescope Array). The MWN spectrum does not allow us to test the hypothesis that 1E 1547.0-5408 had a period of milliseconds at its birth because the particles injected during the early phase of evolution suffered from severe adiabatic and synchrotron losses. Furthermore, both observational and theoretical studies of the wind nebulae around magnetars are required to constrain the wind and the spin-down properties of magnetars.

  13. Characterization of Microsolvated Crown Ethers from Broadband Rotational Spectroscopy

    Science.gov (United States)

    Perez, Cristobal; Schnell, Melanie; Blanco, Susana; Lopez, Juan Carlos

    2016-06-01

    Since they were first synthetized, crown ethers have been extensively used in organometallic chemistry due to their unparalleled binding selectivity with alkali metal cations. From a structural point of view, crown ethers are heterocycles containing oxygen and/or other heteroatoms, although the most common ones are formed from ethylene oxide unit. Crown ethers are conventionally seen as being hydrophilic inside and hydrophobic outside when the structures found for the metal cation complexes are considered. However, crown ethers are extremely flexible and in isolation may present a variety of stable conformations so that their structure may be easily adapted in presence of a strong ligand as an alkali metal cation minimize the energy of the resulting complex. Water can be considered a soft ligand which interacts with crown ethers through moderate hydrogen bonds. It is thus interesting to investigate which conformers are selected by water to form complexes, the preferred interaction sites and the possible conformational changes due to the presence of one or more water molecules. Previous studies identified microsolvated crown ethers but in all cases with a chromophore group attached to the structure. Here we present a broadband rotational spectroscopy study of microsolvated crown ethers produced in a pulsed molecular jet expansion. Several 1:1 and 1:2 crown ether:water aggregates are presented for 12-crown-4, 15-crown-5 and 18-crown-6. Unambiguous identification of the structures has been achieved using isotopic substitution within the water unit. The subtle changes induced in the structures of the crown ether monomer upon complexation and the hydrogen-bonding network that hold them together will be also discussed. F. Gámez, B. Martínez-Haya, S. Blanco,J. C. López and J. L. Alonso, Phys. Chem. Chem. Phys. 2014, 14 12912-12918 V. A. Shubert, C.W. Müller and T. Zwier, J. Phys. Chem. A 2009, 113 8067-8079

  14. Rapid characterisation of large earthquakes by multiple seismic broadband arrays

    Directory of Open Access Journals (Sweden)

    D. Roessler

    2010-04-01

    Full Text Available An automatic procedure is presented to retrieve rupture parameters for large earthquakes along the Sunda arc subduction zone. The method is based on standard array analysis and broadband seismograms registered within 30°–100° epicentral distance. No assumptions on source mechanism are required. By means of semblance the coherency of P waveforms is analysed at separate large-aperture arrays. Waveforms are migrated to a 10°×10° wide source region to study the spatio-temporal evolution of earthquakes at each array. The multiplication of the semblance source maps resulting at each array increases resolution. Start, duration, extent, direction, and propagation velocity are obtained and published within 25 min after the onset of the event. First preliminary results can be obtained even within 16 min. Their rapid determination may improve the mitigation of the earthquake and tsunami hazard. Real-time application will provide rupture parameters to the GITEWS project (German Indonesian Tsunami Early Warning System. The method is applied to the two M8.0 Sumatra earthquakes on 12 September 2007, to the M7.4 Java earthquake on 2 September 2009, and to major subduction earthquakes that have occurred along Sumatra and Java since 2000. Obtained rupture parameters are most robust for the largest earthquakes with magnitudes M≥8. The results indicate that almost the entire seismogenic part of the subduction zone off the coast of Sumatra has been ruptured. Only the great Sumatra event in 2004 and the M7.7 Java event on 17 July 2006 could reach to or close to the surface at the trench. Otherwise, the rupturing was apparently confined to depths below 25 km. Major seismic gaps seem to remain off the coast of Padang and the southern tip of Sumatra.

  15. A miniaturized reconfigurable broadband attenuator based on RF MEMS switches

    Science.gov (United States)

    Guo, Xin; Gong, Zhuhao; Zhong, Qi; Liang, Xiaotong; Liu, Zewen

    2016-07-01

    Reconfigurable attenuators are widely used in microwave measurement instruments. Development of miniaturized attenuation devices with high precision and broadband performance is required for state-of-the-art applications. In this paper, a compact 3-bit microwave attenuator based on radio frequency micro-electro-mechanical system (RF MEMS) switches and polysilicon attenuation modules is presented. The device comprises 12 ohmic contact MEMS switches, π-type polysilicon resistive attenuation modules and microwave compensate structures. Special attention was paid to the design of the resistive network, compensate structures and system simulation. The device was fabricated using micromachining processes compatible with traditional integrated circuit fabrication processes. The reconfigurable attenuator integrated with RF MEMS switches and resistive attenuation modules was successfully fabricated with dimensions of 2.45  ×  4.34  ×  0.5 mm3, which is 1/1000th of the size of a conventional step attenuator. The measured RF performance revealed that the attenuator provides 10-70 dB attenuation at 10 dB intervals from 0.1-20 GHz with an accuracy better than  ±1.88 dB at 60 dB and an error of less than 2.22 dB at 10 dB. The return loss of each state of the 3-bit attenuator was better than 11.95 dB (VSWR  <  1.71) over the entire operating band.

  16. Performance analysis of OFDM modulation on indoor broadband PLC channels

    Science.gov (United States)

    Antonio Cortés, José; Díez, Luis; Cañete, Francisco Javier; Sánchez-Martínez, Juan José; Entrambasaguas, José Tomás

    2011-12-01

    Indoor broadband power-line communications is a suitable technology for home networking applications. In this context, orthogonal frequency-division multiplexing (OFDM) is the most widespread modulation technique. It has recently been adopted by the ITU-T Recommendation G.9960 and is also used by most of the commercial systems, whose number of carriers has gone from about 100 to a few thousands in less than a decade. However, indoor power-line channels are frequency-selective and exhibit periodic time variations. Hence, increasing the number of carriers does not always improves the performance, since it reduces the distortion because of the frequency selectivity, but increases the one caused by the channel time variation. In addition, the long impulse response of power-line channels obliges to use an insufficient cyclic prefix. Increasing its value reduces the distortion, but also the symbol rate. Therefore, there are optimum values for both modulation parameters. This article evaluates the performance of an OFDM system as a function of the number of carriers and the cyclic prefix length, determining their most appropriate values for the indoor power-line scenario. This task must be accomplished by means of time-consuming simulations employing a linear time-varying filtering, since no consensus on a tractable statistical channel model has been reached yet. However, this study presents a simpler procedure in which the distortion because of the frequency selectivity is computed using a time-invariant channel response, and an analytical expression is derived for the one caused by the channel time variation.

  17. Study of bidirectional broadband passive optical network (BPON) using EDFA

    Science.gov (United States)

    Almalaq, Yasser

    Optical line terminals (OLTs) and number of optical network units (ONUs) are two main parts of passive optical network (PON). OLT is placed at the central office of the service providers, the ONUs are located near to the end subscribers. When compared with point-to-point design, a PON decreases the number of fiber used and central office components required. Broadband PON (BPON), which is one type of PON, can support high-speed voice, data and video services to subscribers' residential homes and small businesses. In this research, by using erbium doped fiber amplifier (EDFA), the performance of bi-directional BPON is experimented and tested for both downstream and upstream traffic directions. Ethernet PON (E-PON) and gigabit PON (G-PON) are the two other kinds of passive optical network besides BPON. The most beneficial factor of using BPON is it's reduced cost. The cost of the maintenance between the central office and the users' side is suitable because of the use of passive components, such as a splitter in the BPON architecture. In this work, a bidirectional BPON has been analyzed for both downstream and upstream cases by using bit error rate analyzer (BER). BER analyzers test three factors that are the maximum Q factor, minimum bit error rate, and eye height. In other words, parameters such as maximum Q factor, minimum bit error rate, and eye height can be analyzed utilized a BER tester. Passive optical components such as a splitter, optical circulator, and filters have been used in modeling and simulations. A 12th edition Optiwave simulator has been used in order to analyze the bidirectional BPON system. The system has been tested under several conditions such as changing the fiber length, extinction ratio, dispersion, and coding technique. When a long optical fiber above 40km was used, an EDFA was used in order to improve the quality of the signal.

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

    Data.gov (United States)

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

  19. Broadband Printed Cross-Dipole Element with Four Polarization Reconfigurations for Mobile Base Station Array Antenna Applications

    Directory of Open Access Journals (Sweden)

    Soon-Young Eom

    2011-01-01

    Full Text Available This paper describes a broadband printed cross-dipole element with four polarization reconfigurations (BPCDE_PR. The BPCDE_PR can configure two linear and two circular polarizations in the operating band of 1.7–2.5 GHz. To implement the broadband polarization reconfigurations, switched network type broadband phase shifters are proposed and designed. The fabricated BPCDE_PR prototype with switched network including broadband phase shifters shows good electrical performances and the desired polarization reconfigurable functions in the operating band.

  20. Service Class Resource Management For Green Wireless-Optical Broadband Access NetworksWOBAN

    Directory of Open Access Journals (Sweden)

    SRUTHY.S

    2015-08-01

    Full Text Available Abstract-Broadband access networks have become an essential part of worldwide communication systems because of the exponential growth of broadband services such as video on demand high definition TV internet protocol TV and video conferencing. Exponential growth in the volume of wireless data boosted by the growing popularity of mobile devices such as smartphone and tablets has forced the telecommunication industries to rethink the way networks are currently designed and to focus on the development of high-capacity mobile broadband networks. In response to this challenge researchers have been working toward the development of an integrated wireless optical broadband access network. Two major candidate technologies which are currently known for their high capacity as well as quality of service QoS for multimedia traffic are passive optical networks PON and fourth generation 4G wireless networks. PON is a wired access technology well known for its cost efficiency and high capacity whereas 4G is a wireless broadband access technology which has achieved broad market acceptance because of its ease of deployment ability to offer mobility and its cost efficiency. Integration of PON and 4G technologies in the form of wireless-optical broadband access networks offers advantages such as extension of networks in rural areas support for mobile broadband services and quick deployment of broadband networks. These two technologies however have different design architectures for handling broadband services that require quality of service. For example 4G networks use traffic classification for supporting different QoS demands whereas the PON architecture has no such mechanism to differentiate between types of traffic. These two technologies also differ in their power saving mechanisms. Propose a service class mapping for the integrated PON-4G network which is based on the MG1 queuing model and class-based power saving mechanism which significantly improves the

  1. Digital Divides and the 'First Mile': Framing First Nations Broadband Development in Canada

    Directory of Open Access Journals (Sweden)

    Rob McMahon

    2011-05-01

    Full Text Available Across Canada, rural and remote First Nations face a significant 'digital divide'. As self-determining autonomous nations in Canada, these communities are building broadband systems to deliver public services to their members and residents. To address this challenge, First Nations are working towards a variety of innovative, locally driven broadband development initiatives. This paper contributes a theoretical discussion that frames our understanding of these initiatives by drawing on the paradigm of the 'First Mile' (Paisley & Richardson, 1998. We argue that broadband development policy in Canada must be re-framed to address the specific needs of First Nations. The First Mile position foregrounds community-based involvement, control, and ownership: a consideration we suggest has particular resonance for First Nations. This is because it holds potential to move beyond the historical context of paternalistic, colonial-derived development policies, in the context of broadband systems development. We argue First Nations broadband projects offer on-the-ground examples of a First Mile approach, and call for more research in this area.

  2. Design of broadband beamformers based on an expected response interpolation technique

    Institute of Scientific and Technical Information of China (English)

    GUO Qili; SUN Chao; YANG Yixin

    2006-01-01

    A method for designing broadband beamformers based on an expected response interpolation technique was proposed, with the aim of reducing the heavy optimization burden in the broadband beamformer design problem. In the method, some typical fr equencies in the designing frequency band are selected and the optimal array weights are designed on these typical frequencies, based on which a broadband expected response function is constructed.Then, FIR filters are designed to realize the broadband beamforming over the whole designing frequency band, via the interpolation technique which is utilized to the expected responses of the FIR filters. Broadband beamforming can be fulfilled by applying these filters to each of the sensors in the array. By using the proposed method, designers need not to divide the whole designing frequency band into narrow subbands so as to make the narrow band assumption valid, which not only reduces the heavy designing burden, but also releases the requirement for measurements at fine frequency grids in the robust beamformer design. Results of both computer simulations and watertank experiments verify the effectiveness of the proposed method.

  3. Investigating the Factors Affecting Residential Consumer Adoption of Broadband in India

    Directory of Open Access Journals (Sweden)

    Amir Manzoor

    2014-10-01

    Full Text Available This study aims to explore in detail the factors that affect the consumer behavioral intention to adopt broadband Internet in a developing country perspective. Various attitudinal, normative, and control constructs were identified and investigated for their possible influence on broadband Internet adoption. The empirical data for this study were collected using a self-administered questionnaire that included items related to various attitudinal, normative, and control constructs. Descriptive statistics and regression analysis were used to test these constructs for their possible influence on Indian consumers’ adoption of broadband Internet. The findings suggest that perceived ease of use (PE, social outcomes (SO, hedonic outcomes (HO, service quality (SQ, facilitating conditions resources (FCR, and self-efficacy (SE were very significant predictors of Indian consumers’ behavioral intention to adopt broadband Internet. This study has multifold significance. The integrated research framework used in this study is an extension of previous well-established research models (such as Model of Adoption of Technology in Households [MATH], Diffusion of Innovation [DOI], and Theory of Planned Behavior [TPB] and provides an enhanced comprehension of broadband Internet by the Indian household consumers.

  4. Broadband and Narrowband Search for z < 1 Analogs of High Redshift Star Forming Galaxies

    Science.gov (United States)

    Rosenwasser, Benjamin; Barger, Amy J.; Wold, Isak; Lauchlan Cowie, Lennox

    2017-01-01

    Studies of high redshift (z > 6) galaxies rely on extreme broadband colors from Spitzer/IRAC to select samples of low-mass star forming galaxies. These broadband excess searches are biased towards galaxies with the strongest emission lines, and the extent to which existing studies miss fainter galaxies with lower star formation rates remains unknown. Using both broadband (BB) and narrowband (NB) imaging from the HyperSuprimeCam (HSC) and SuprimeCam (SC) on the Subaru Telescope, we have performed a search for z population. The search was performed over roughly 4 square degrees centered on the COSMOS field, and the narrowband filters allow us to probe fainter emission lines than the broadband searches. We carried out spectral followup of our BB excess and NB excess samples using WIYN/Hydra to measure redshifts and line ratios in order to understand the biases in the different selection techniques. We also investigate the rest frame UV properties of our sample using data from GALEX. This study demonstrates the effectiveness of using broadband colors to select intermediate redshift emission line galaxies.

  5. Estimating carbon dioxide fluxes from temperate mountain grasslands using broad-band vegetation indices

    Directory of Open Access Journals (Sweden)

    G. Wohlfahrt

    2010-02-01

    Full Text Available The broad-band normalised difference vegetation index (NDVI and the simple ratio (SR were calculated from measurements of reflectance of photosynthetically active and short-wave radiation at two temperate mountain grasslands in Austria and related to the net ecosystem CO2 exchange (NEE measured concurrently by means of the eddy covariance method. There was no significant statistical difference between the relationships of midday mean NEE with narrow- and broad-band NDVI and SR, measured during and calculated for that same time window, respectively. The skill of broad-band NDVI and SR in predicting CO2 fluxes was higher for metrics dominated by gross photosynthesis and lowest for ecosystem respiration, with NEE in between. A method based on a simple light response model whose parameters were parameterised based on broad-band NDVI allowed to improve predictions of daily NEE and is suggested to hold promise for filling gaps in the NEE time series. Relationships of CO2 flux metrics with broad-band NDVI and SR however generally differed between the two studied grassland sites indicting an influence of additional factors not yet accounted for.

  6. A Design of 45-Degree Dual-Polarization Broadband Plane Station Antenna

    Directory of Open Access Journals (Sweden)

    Jianming Zhou

    2015-01-01

    Full Text Available A new broadband planar dual-polarization base station antenna is proposed, the antenna consists of two broadband plane coplanar base station antenna units, and so it has features of plane antenna. Two broadband plane station antenna units can, respectively, form double polarization in the direction. We analyzed the relative positions between the two antenna units and their effects on the performances of the antenna, especially for the influence of isolation. Broadband antenna has the characteristics of the broadband station antenna, and bandwidth is also guaranteed. The measured results show that the antenna can obtain 45% relative bandwidth, and 30 dB isolation degree also can be got, and the radiation performance is also good. Measurement results confirmed that the antenna gain can be guaranteed among 48% relative bandwidth, 15 dB of gain is got among bandwidth of 1.69–2.78 GHz, the isolation degree of different polarization method can reach 30 dB, and the measurement gain of two polarization methods of antenna both can reach 8.5 dBi.

  7. Mapping Surface Broadband Albedo from Satellite Observations: A Review of Literatures on Algorithms and Products

    Directory of Open Access Journals (Sweden)

    Ying Qu

    2015-01-01

    Full Text Available Surface albedo is one of the key controlling geophysical parameters in the surface energy budget studies, and its temporal and spatial variation is closely related to the global climate change and regional weather system due to the albedo feedback mechanism. As an efficient tool for monitoring the surfaces of the Earth, remote sensing is widely used for deriving long-term surface broadband albedo with various geostationary and polar-orbit satellite platforms in recent decades. Moreover, the algorithms for estimating surface broadband albedo from satellite observations, including narrow-to-broadband conversions, bidirectional reflectance distribution function (BRDF angular modeling, direct-estimation algorithm and the algorithms for estimating albedo from geostationary satellite data, are developed and improved. In this paper, we present a comprehensive literature review on algorithms and products for mapping surface broadband albedo with satellite observations and provide a discussion of different algorithms and products in a historical perspective based on citation analysis of the published literature. This paper shows that the observation technologies and accuracy requirement of applications are important, and long-term, global fully-covered (including land, ocean, and sea-ice surfaces, gap-free, surface broadband albedo products with higher spatial and temporal resolution are required for climate change, surface energy budget, and hydrological studies.

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

    Energy Technology Data Exchange (ETDEWEB)

    Bood, Joakim

    2000-06-01

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

  9. Spectral Analysis of Broadband Seismic Array Data, Tien Shan

    Science.gov (United States)

    Shamshy, S.; Pavlis, G. L.

    2003-12-01

    We used a spectral analysis method to examine amplitude variations of body waves recorded in the Tien Shan region of central Asia. We used broadband data from the Kyrgyz Network (KNET), Kazakhstan Network (KZNET), and from a set of temporary, PASSCAL stations operated from 1997-2000 we refer to as the Ghengis array. A spectral ratio method similar to that used by Wilson and Pavlis (2000) was employed, but with station AAK used as a reference instead of the array median. Spectral ratios were estimated for all teleseismic events and a larger, intermediate depth events from the Hindu-Kush region for all three-components of ground motion and total signal strength on all components. Results are visualized by maps of amplitude for various frequency bands and through the 4-D animation method introduced by Wilson and Pavlis (2000). Data from Hindu-Kush events showed amplitude variations as much as a factor of 100 across the study area with a strong frequency dependence. The largest variations were at the highest frequencies observed near 15 Hz. Stations in the northwestern part of the Tien Shan array show little variation in amplitude relative to the reference station, AAK. In the central and eastern part of the array, the amplitude estimates are significantly smaller at all frequencies. In contrast, for stations in the western Tien Shan near the Talas-Fergana Fault, and the southern Tien Shan near the Tarim Basin, the amplitude values become much larger than the reference site. The teleseismic data show a different pattern and show a somewhat smaller, overall amplitude variation at comparable frequencies. The northern part of the array again shows small variations relative to the reference stations. There are some amplifications in the southern stations of the array, especially in the Tarim Basin. The higher frequency observations that show large amplifications at stations in the Tarim Basin are readily explained by site effects due to the thick deposits of sediments

  10. Dynamics of the Wulong landslide revealed by broadband seismic records

    Science.gov (United States)

    Li, Zhengyuan; Huang, Xinghui; Xu, Qiang; Yu, Dan; Fan, Junyi; Qiao, Xuejun

    2017-02-01

    The catastrophic Wulong landslide occurred at 14:51 (Beijing time, UTC+8) on 5 June 2009, in Wulong Prefecture, Southwest China. This rockslide occurred in a complex topographic environment. Seismic signals generated by this event were recorded by the seismic network deployed in the surrounding area, and long-period signals were extracted from 8 broadband seismic stations within 250 km to obtain source time functions by inversion. The location of this event was simultaneously acquired using a stepwise refined grid search approach, with an error of 2.2 km. The estimated source time functions reveal that, according to the movement parameters, this landslide could be divided into three stages with different movement directions, velocities, and increasing inertial forces. The sliding mass moved northward, northeastward and northward in the three stages, with average velocities of 6.5, 20.3, and 13.8 m/s, respectively. The maximum movement velocity of the mass reached 35 m/s before the end of the second stage. The basal friction coefficients were relatively small in the first stage and gradually increasing; large in the second stage, accompanied by the largest variability; and oscillating and gradually decreasing to a stable value, in the third stage. Analysis shows that the movement characteristics of these three stages are consistent with the topography of the sliding zone, corresponding to the northward initiation, eastward sliding after being stopped by the west wall, and northward debris flowing after collision with the east slope of the Tiejianggou valley. The maximum movement velocity of the sliding mass results from the largest height difference of the west slope of the Tiejianggou valley. The basal friction coefficients of the three stages represent the thin weak layer in the source zone, the dramatically varying topography of the west slope of the Tiejianggou valley, and characteristics of the debris flow along the Tiejianggou valley. Based on the above

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

    Science.gov (United States)

    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. Single chip super broadband InGaN/GaN LED enabled by nanostructured substrate.

    Science.gov (United States)

    Yin, Stuart Shizhuo; Wang, Chao; Zhu, Wenbin; Yao, Jimmy; Zou, Jun; Lin, Xiaoyan; Luo, Claire

    2014-08-25

    A new type of LED, single chip super broadband InGaN/GaN LED is presented in this paper. The LED is composed of an InGaN/GaN quantum well layer deposited on the nanostructured sapphire substrate, inscribed by femtosecond laser ablation. The super broadband emission is enabled due to the large variation of indium composition in a small local area so that different wavelengths can be emitted over a small area and the summation of these different emission wavelengths forms super broadband emission, which covers the entire visible spectral range. The result of this paper represents a major technological advance in white light LED lighting because it enables single chip white LED lighting without the need of phosphor down converter that can significantly improve the efficiency without the Stokes loss and reduce the cost.

  13. Broadband quasi perfect absorption using chirped multi-layer porous materials

    CERN Document Server

    Jiménez, Noé; Cebrecos, Alejandro; Picó, Rubén; Sánchez-Morcillo, Víctor J; García-Raffi, Lluis M

    2016-01-01

    This work theoretically analyzes the sound absorption properties of a chirped multi-layer porous material including transmission, in particular showing the broadband unidirectional absorption properties of the system. Using the combination of the impedance matching condition and the balance between the leakage and the intrinsic losses as well as the critical coupling condition, the system is designed to have broadband unidirectional and nearly perfect absorption. The transfer and scattering matrix formalism, together with full wave numerical simulations are used to demonstrate the results showing excellent agreement between them. The proposed system allows to construct broadband sound absorbers with improved absorption in the low frequency regime using less than 15 \\% of the complete porous material.

  14. Broadband angle- and permittivity-insensitive nondispersive optical activity based on chiral metamaterials

    CERN Document Server

    Song, Kun; Su, Zhaoxian; Ding, Changlin; Liu, Yahong; Luo, Chunrong; Zhao, Xiaopeng; Bhattarai, Khagendra; Zhou, Jiangfeng

    2016-01-01

    Because of the strong inherent resonances, the giant optical activity obtained via chiral metamaterials generally suffers from high dispersion, which has been a big stumbling block to broadband applications. In this paper, we propose a type of chiral metamaterial consisting of interconnected metal helix structures with four-fold symmetry, which exhibits nonresonant Drude-like response and can therefore avoid the highly dispersive optical activity resulting from resonances. It shows that the well-designed chiral metamaterial can achieve nondispersive and pure optical activity with high transmittance in a broadband frequency range. And the optical activity of multi-layer chiral metamaterials is proportional to the layer numbers of single-layer chiral metamaterial. Most remarkably, the broadband behaviors of nondispersive optical activity and high transmission are insensitive to the incident angles of electromagnetic waves and permittivity of dielectric substrate, thereby enabling more flexibility in polarizatio...

  15. Broadband shifts in LFP power spectra are correlated with single-neuron spiking in humans

    Science.gov (United States)

    Manning, Jeremy R.; Jacobs, Joshua; Fried, Itzhak; Kahana, Michael J.

    2010-01-01

    A fundamental question in neuroscience concerns the relation between the spiking of individual neurons and the aggregate electrical activity of neuronal ensembles as seen in local-field potentials (LFPs). Because LFPs reflect both spiking activity and subthreshold events, this question is not simply one of data aggregation. Recording from 20 neurosurgical patients, we directly examined the relation between LFPs and neuronal spiking. Examining 2,030 neurons in widespread brain regions, we found that firing rates were positively correlated with broadband (2 – 150 Hz) shifts in the LFP power spectrum. In contrast, narrowband oscillations correlated both positively and negatively with firing rates at different recording sites. Broadband power shifts were a more-reliable predictor of neuronal spiking than narrowband power shifts. These findings suggest that broadband LFP power provides valuable information concerning neuronal activity beyond that contained in narrowband oscillations. PMID:19864573

  16. Reducing Broadband Shortwave Radiometer Calibration-Bias Caused by Longwave Irradiance in the Reference Direct Beam

    Energy Technology Data Exchange (ETDEWEB)

    Reda, Ibrahim; Andreas, Afshin; Dooraghi, Mike; Sengupta, Manajit; Habte, Aron; Kutchenreiter, Mark

    2017-01-01

    Shortwave radiometers such as pyranometers, pyrheliometers, and photovoltaic cells are calibrated with traceability to consensus reference, maintained by Absolute Cavity Radiometers (ACRs). The ACR is an open cavity with no window, and measures the extended broadband spectrum of the terrestrial direct solar beam irradiance, unlike shortwave radiometers that cover a limited range of the spectrum. The difference between the two spectral ranges may lead to calibration bias that can exceed 1%. This article describes a method to reduce the calibration bias resulting from using broadband ACRs to calibrate shortwave radiometers, by using an ACR with Schott glass window to measure the reference broadband shortwave irradiance in the terrestrial direct solar beam from 0.3 um to 3 um.

  17. Reduction of blurring in broadband volume holographic imaging using a deconvolution method

    Science.gov (United States)

    Lv, Yanlu; Zhang, Xuanxuan; Zhang, Dong; Zhang, Lin; Luo, Yuan; Luo, Jianwen

    2016-01-01

    Volume holographic imaging (VHI) is a promising biomedical imaging tool that can simultaneously provide multi-depth or multispectral information. When a VHI system is probed with a broadband source, the intensity spreads in the horizontal direction, causing degradation of the image contrast. We theoretically analyzed the reason of the horizontal intensity spread, and the analysis was validated by the simulation and experimental results of the broadband impulse response of the VHI system. We proposed a deconvolution method to reduce the horizontal intensity spread and increase the image contrast. Imaging experiments with three different objects, including bright field illuminated USAF test target and lung tissue specimen and fluorescent beads, were carried out to test the performance of the proposed method. The results demonstrated that the proposed method can significantly improve the horizontal contrast of the image acquire by broadband VHI system. PMID:27570703

  18. Volterra series based predistortion for broadband RF power amplifiers with memory effects

    Institute of Scientific and Technical Information of China (English)

    Jin Zhe; Song Zhihuan; He Jiaming

    2008-01-01

    RF power amplifiers(PAs)are usually considered as memoryless devices in most existing predistortion techniques.However,in broadband communication systems,such as WCDMA,the PA memory effects are significant,and memoryless predistortion cannot linearize the PAs effectively.After analyzing the PA memory effects,a novel predistortion method based on the simplified Volterra series is proposed to linearize broadband RF PAs with memory effects.The indirect learning architecture is adopted to design the predistortion scheme and the recursive least squares algorithm with forgetting factor is applied to identify the parameters of the predistorter.Simulation results show that the proposed predistortion method can compensate the nonlinear distortion and memory effects of broadband RF PAs effectively.

  19. Broadband quasi perfect absorption using chirped multi-layer porous materials

    Science.gov (United States)

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

    2016-12-01

    This work theoretically analyzes the sound absorption properties of a chirped multi-layer porous material including transmission, in particular showing the broadband unidirectional absorption properties of the system. Using the combination of the impedance matching condition and the balance between the leakage and the intrinsic losses, the system is designed to have broadband unidirectional and quasi perfect absorption. The transfer and scattering matrix formalism, together with numerical simulations based on the finite element method are used to demonstrate the results showing excellent agreement between them. The proposed system allows to construct broadband sound absorbers with improved absorption in the low frequency regime using less amount of material than the complete bulk porous layer.

  20. Metamaterial buffer for broadband non-resonant impedance matching of obliquely incident acoustic waves.

    Science.gov (United States)

    Fleury, Romain; Alù, Andrea

    2014-12-01

    Broadband impedance matching and zero reflection of acoustic waves at a planar interface between two natural materials is a rare phenomenon, unlike its optical counterpart, frequently observed for polarized light incident at the Brewster angle. In this article, it is shown that, by inserting a metamaterial layer between two acoustic materials with different impedance, it is possible to artificially realize an extremely broadband Brewster-like acoustic intromission angle window, in which energy is totally transmitted from one natural medium to the other. The metamaterial buffer, composed of acoustically hard materials with subwavelength tapered apertures, provides an interesting way to match the impedances of two media in a broadband fashion, different from traditional methods like quarter-wave matching or Fabry-Pérot resonances, inherently narrowband due to their resonant nature. This phenomenon may be interesting for a variety of applications including energy harvesting, acoustic imaging, ultrasonic transducer technology, and noise control.