WorldWideScience

Sample records for broadband

  1. Broadband radiometer

    Science.gov (United States)

    Cannon, T.W.

    1994-07-26

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

  2. Adoption of Broadband Services

    DEFF Research Database (Denmark)

    Falch, Morten

    2008-01-01

    Broadband is seen as a key infrastructure for developing the information society. For this reason many Governments are actively engaged in stimulating investments in broadband infrastructures and use of broadband services. This chapter compares a wide range of broadband strategies in the most...... 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...

  3. Broadband Electromagnetic Technology

    Science.gov (United States)

    2011-06-23

    The objectives of this project are to continue the enhancements to the combined Broadband Electromagnetic and Full Encirclement Unit (BEM-FEU) technologies and to evaluate the systems capability in the laboratory and the field. The BEM instrument ...

  4. Broadband Radiometric LED Measurements.

    Science.gov (United States)

    Eppeldauer, G P; Cooksey, C C; Yoon, H W; Hanssen, L M; Podobedov, V B; Vest, R E; Arp, U; Miller, C C

    2016-01-01

    At present, broadband radiometric measurements of LEDs with uniform and low-uncertainty results are not available. Currently, either complicated and expensive spectral radiometric measurements or broadband photometric LED measurements are used. The broadband photometric measurements are based on the CIE standardized V(λ) function, which cannot be used in the UV range and leads to large errors when blue or red LEDs are measured in its wings, where the realization is always poor. Reference irradiance meters with spectrally constant response and high-intensity LED irradiance sources were developed here to implement the previously suggested broadband radiometric LED measurement procedure [1, 2]. Using a detector with spectrally constant response, the broadband radiometric quantities of any LEDs or LED groups can be simply measured with low uncertainty without using any source standard. The spectral flatness of filtered-Si detectors and low-noise pyroelectric radiometers are compared. Examples are given for integrated irradiance measurement of UV and blue LED sources using the here introduced reference (standard) pyroelectric irradiance meters. For validation, the broadband measured integrated irradiance of several LED-365 sources were compared with the spectrally determined integrated irradiance derived from an FEL spectral irradiance lamp-standard. Integrated responsivity transfer from the reference irradiance meter to transfer standard and field UV irradiance meters is discussed.

  5. Broadband Radiometric LED Measurements

    Science.gov (United States)

    Eppeldauer, G. P.; Cooksey, C. C.; Yoon, H. W.; Hanssen, L. M.; Podobedov, V. B.; Vest, R. E.; Arp, U.; Miller, C. C.

    2017-01-01

    At present, broadband radiometric measurements of LEDs with uniform and low-uncertainty results are not available. Currently, either complicated and expensive spectral radiometric measurements or broadband photometric LED measurements are used. The broadband photometric measurements are based on the CIE standardized V(λ) function, which cannot be used in the UV range and leads to large errors when blue or red LEDs are measured in its wings, where the realization is always poor. Reference irradiance meters with spectrally constant response and high-intensity LED irradiance sources were developed here to implement the previously suggested broadband radiometric LED measurement procedure [1, 2]. Using a detector with spectrally constant response, the broadband radiometric quantities of any LEDs or LED groups can be simply measured with low uncertainty without using any source standard. The spectral flatness of filtered-Si detectors and low-noise pyroelectric radiometers are compared. Examples are given for integrated irradiance measurement of UV and blue LED sources using the here introduced reference (standard) pyroelectric irradiance meters. For validation, the broadband measured integrated irradiance of several LED-365 sources were compared with the spectrally determined integrated irradiance derived from an FEL spectral irradiance lamp-standard. Integrated responsivity transfer from the reference irradiance meter to transfer standard and field UV irradiance meters is discussed. PMID:28649167

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

    DEFF Research Database (Denmark)

    Olivero, Massimo; Svalgaard, Mikael

    2005-01-01

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

  7. Dual broadband metamaterial absorber.

    Science.gov (United States)

    Kim, Young Ju; Yoo, Young Joon; Kim, Ki Won; Rhee, Joo Yull; Kim, Yong Hwan; Lee, YoungPak

    2015-02-23

    We propose polarization-independent and dual-broadband metamaterial absorbers at microwave frequencies. This is a periodic meta-atom array consisting of metal-dielectric-multilayer truncated cones. We demonstrate not only one broadband absorption from the fundamental magnetic resonances but additional broadband absorption in high-frequency range using the third-harmonic resonance, by both simulation and experiment. In simulation, the absorption was over 90% in 3.93-6.05 GHz, and 11.64-14.55 GHz. The corresponding experimental absorption bands over 90% were 3.88-6.08 GHz, 9.95-10.46 GHz and 11.86-13.84 GHz, respectively. The origin of absorption bands was elucidated. Furthermore, it is independent of polarization angle owing to the multilayered circular structures. The design is scalable to smaller size for the infrared and the visible ranges.

  8. 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...

  9. 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 by micro......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...

  10. Toward broadband mechanical spectroscopy

    DEFF Research Database (Denmark)

    Hecksher, Tina; Torchinsky, Darius; Klieber, Christoph

    2017-01-01

    Diverse material classes exhibit qualitatively similar behavior when made viscous upon cooling toward the glass transition, suggesting a common theoretical basis. We used seven different measurement methods to determine the mechanical relaxation kinetics of a prototype molecular glass former over...... a temporal range of 13 decades and over a temperature range spanning liquid to glassy states. The data conform to time–temperature superposition for the main (alpha) process and to a scaling relation of schematic mode-coupling theory. The broadband mechanical measurements demonstrated have fundamental...

  11. BPL (Broadband Power Line)

    OpenAIRE

    Peralta, Arturo

    2010-01-01

    El mundo actual requiere cada vez más el estar conectados con la sociedad de la Información y el Conocimiento, esto demanda que en los hogares, lugares de turismo, trabajos, universidades, etcétera, se cuente con una conexión a Internet de Alta Velocidad, que además sea segura y confiable. En este documento se presenta las características más importantes de la tecnología BPL (Broadband Power Line) o PLC (Power Line Comunication), la cual permite brindar el servicio de Internet ...

  12. Broadband frequency conversion

    DEFF Research Database (Denmark)

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

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

  13. 75 FR 29516 - Broadband Researchers' Data Workshop

    Science.gov (United States)

    2010-05-26

    ... Administration Broadband Researchers' Data Workshop AGENCY: National Telecommunications and Information... demonstrated in the agency's October 30, 2009, Broadband Data Transparency Public Workshop.\\2\\ \\2\\ See http...

  14. Broadband unidirectional ultrasound propagation

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, Dipen N.; Pantea, Cristian

    2017-12-12

    A passive, linear arrangement of a sonic crystal-based apparatus and method including a 1D sonic crystal, a nonlinear medium, and an acoustic low-pass filter, for permitting unidirectional broadband ultrasound propagation as a collimated beam for underwater, air or other fluid communication, are described. The signal to be transmitted is first used to modulate a high-frequency ultrasonic carrier wave which is directed into the sonic crystal side of the apparatus. The apparatus processes the modulated signal, whereby the original low-frequency signal exits the apparatus as a collimated beam on the side of the apparatus opposite the sonic crystal. The sonic crystal provides a bandpass acoustic filter through which the modulated high-frequency ultrasonic signal passes, and the nonlinear medium demodulates the modulated signal and recovers the low-frequency sound beam. The low-pass filter removes remaining high-frequency components, and contributes to the unidirectional property of the apparatus.

  15. Broadband Advanced Spectral System Project

    Data.gov (United States)

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

  16. Does broadband internet affect fertility?

    OpenAIRE

    Billari, Francesco C.; Giuntella, Osea; Stella, Luca

    2017-01-01

    The spread of high-speed Internet epitomizes the digital revolution, affecting several aspects of our life. Using German panel data, we test whether the availability of broadband Internet influences fertility choices in a low-fertility setting, which is well-known for the difficulty to combine work and family life. We exploit a strategy devised by Falck et al. (2014) to obtain causal estimates of the impact of broadband on fertility. We find positive effects of highspeed Internet availability...

  17. Broadband accelerator control network

    Energy Technology Data Exchange (ETDEWEB)

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

    1983-01-01

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

  18. 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.

  19. ATST visible broadband imager

    Science.gov (United States)

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

    2012-09-01

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

  20. 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

  1. Broadband Transmission EPR Spectroscopy

    Science.gov (United States)

    Hagen, Wilfred R.

    2013-01-01

    EPR spectroscopy employs a resonator operating at a single microwave frequency and phase-sensitive detection using modulation of the magnetic field. The X-band spectrometer is the general standard with a frequency in the 9–10 GHz range. Most (bio)molecular EPR spectra are determined by a combination of the frequency-dependent electronic Zeeman interaction and a number of frequency-independent interactions, notably, electron spin – nuclear spin interactions and electron spin – electron spin interactions, and unambiguous analysis requires data collection at different frequencies. Extant and long-standing practice is to use a different spectrometer for each frequency. We explore the alternative of replacing the narrow-band source plus single-mode resonator with a continuously tunable microwave source plus a non-resonant coaxial transmission cell in an unmodulated external field. Our source is an arbitrary wave digital signal generator producing an amplitude-modulated sinusoidal microwave in combination with a broadband amplifier for 0.8–2.7 GHz. Theory is developed for coaxial transmission with EPR detection as a function of cell dimensions and materials. We explore examples of a doublet system, a high-spin system, and an integer-spin system. Long, straigth, helical, and helico-toroidal cells are developed and tested with dilute aqueous solutions of spin label hydroxy-tempo. A detection limit of circa 5 µM HO-tempo in water at 800 MHz is obtained for the present setup, and possibilities for future improvement are discussed. PMID:23555819

  2. 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 ...

  3. Observations involving broadband impedance modelling

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-08-01

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

  4. 75 FR 27984 - Broadband Technology Opportunities Program

    Science.gov (United States)

    2010-05-19

    ... interoperability framework for use across the United States. The FCC's National Broadband Plan recognized that... Research, Projects, at http://www.pscr.gov/projects/broadband/700mhz/700mhz.php . Pursuant to the eligible...

  5. Broadband Synthetic Ground Motion Records

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The dataset contains broadband synthetic ground motion records for three events: 1) 1994 M6.7 Northridge, CA, 2) 1989 M7.0 Loma Prieta, CA, and 3) 1999 M7.5 Izmit,...

  6. Linearization of broadband microwave amplifier

    Directory of Open Access Journals (Sweden)

    Đorić Aleksandra

    2014-01-01

    Full Text Available The linearization of broadband power amplifier for application in the frequency range 0.9-1.3 GHz is considered in this paper. The amplifier is designed for LDMOSFET characterized by the maximum output power 4W designing the broadband lumped element matching circuits and matching circuits in topologies that combines LC elements and transmission lines. The linearization of the amplifier is carried out by the second harmonics of the fundamental signals injected at the input and output of the amplifier transistor. The effects of linearization are considered for the case of two sinusoidal signals separated in frequency by different intervals up to 80 MHz ranging input power levels to saturation. [Projekat Ministarstva nauke Republike Srbije, br. TR-32052

  7. Broadband light-emitting diode

    Science.gov (United States)

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

    1998-01-01

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

  8. Analysis of the Proposed Ghana Broadband Strategy

    DEFF Research Database (Denmark)

    Williams, Idongesit; Botwe, Yvonne

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

  9. 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

  10. Broadband Traffic Forecasting in the Transport Network

    Directory of Open Access Journals (Sweden)

    Valentina Radojičić

    2012-07-01

    Full Text Available This paper proposes a modification of traffic forecast model generated by residential and small business (SOHO, Small Office Home Office users. The model includes forecasted values of different relevant factors and competition on broadband market. It allows forecasting the number of users for various broadband technologies and interaction impact of long-standing technologies as well as the impact of the new technology entrant on the market. All the necessary parameters are evaluated for the Serbian broadband market. The long-term forecasted results of broadband traffic are given. The analyses and evaluations performed are important inputs for the transport network resources planning.

  11. 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...... 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...

  12. POTS to broadband ... cable modems.

    Science.gov (United States)

    Kabachinski, Jeff

    2003-01-01

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

  13. 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.

  14. 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

  15. 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...

  16. Electronically Switchable Broadband Metamaterial Absorber.

    Science.gov (United States)

    Lee, Dongju; Jeong, Heijun; Lim, Sungjoon

    2017-07-07

    In this study, the novel electronically switchable broadband metamaterial absorber, using a PIN diode, is proposed. The unit cell of the absorber was designed with a Jerusalem-cross resonator and an additive ring structure, based on the FR-4 dielectric substrate. Chip resistors and PIN diodes were used to provide both a broadband characteristic and a switching capability. To satisfy the polarization insensitivity, the unit cell was designed as a symmetrical structure, including the DC bias network, electronic devices, and conductor patterns. The performance of the proposed absorber was verified using full-wave simulation and measurements. When the PIN diode was in the ON state, the proposed absorber had a 90% absorption bandwidth from 8.45-9.3 GHz. Moreover, when the PIN diode was in the OFF state, the 90% absorption bandwidth was 9.2-10.45 GHz. Therefore, the absorption band was successfully switched between the low-frequency band and the high-frequency band as the PIN diode was switched between the ON and OFF states. Furthermore, the unit cell of the proposed absorber was designed as a symmetrical structure, and its performance showed insensitivity with respect to the polarization angle.

  17. 78 FR 32165 - Broadband Over Power Lines

    Science.gov (United States)

    2013-05-29

    ... providing for Access BPL technology--which has potential applications for broadband and Smart Grid uses... strike an appropriate balance between the dual objectives of providing for Access BPL technology--which has potential applications for broadband and Smart Grid uses--while protecting incumbent radio...

  18. 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…

  19. Customer Churn Prediction for Broadband Internet Services

    Science.gov (United States)

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

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

  20. 47 CFR 27.1305 - Shared wireless broadband network.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Shared wireless broadband network. 27.1305... broadband network. The Shared Wireless Broadband Network developed by the 700 MHz Public/Private Partnership must be designed to meet requirements associated with a nationwide, public safety broadband network. At...

  1. 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. At...

  2. Analyzing Broadband Divide in the Farming Sector

    DEFF Research Database (Denmark)

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

    2013-01-01

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

  3. 75 FR 3820 - Broadband Initiatives Program

    Science.gov (United States)

    2010-01-22

    ... the RUS, under the Recovery Act. Broadband means providing two-way data transmission with advertised... no cost (including no costs for installation, activation, or other hidden fees) and to providing to...

  4. 75 FR 14131 - Broadband Technology Opportunities Program

    Science.gov (United States)

    2010-03-24

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE... Program AGENCY: National Telecommunications and Information Administration, U.S. Department of Commerce... for the electronic submission of CCI projects under the Broadband Technology Opportunities Program...

  5. 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.

  6. Broadband networks, smart grids and climate change

    CERN Document Server

    Noam, Eli M; Kranz, Johann J

    2015-01-01

    Noted scholars and professionals from the energy and telecommunications businesses explain in this volume how the convergence of broadband services and responsive 'smart' energy grids could help to mitigate climate change and boost corporation profits.

  7. 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...

  8. Ultra-broadband photonic internet

    Science.gov (United States)

    Romaniuk, Ryszard S.

    2011-06-01

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

  9. Broadband in schools: towards a definition and model of broadband for South African schools

    CSIR Research Space (South Africa)

    Ford, Merryl

    2017-05-01

    Full Text Available South Africa is about to provide broadband internet connectivity to all schools in the country via the implementation of the national broadband policy. The challenge is to ensure a balance between the schools’ demand-side usage and supply...

  10. Identifying Broadband Rotational Spectra with Neural Networks

    Science.gov (United States)

    Zaleski, Daniel P.; Prozument, Kirill

    2017-06-01

    A typical broadband rotational spectrum may contain several thousand observable transitions, spanning many species. Identifying the individual spectra, particularly when the dynamic range reaches 1,000:1 or even 10,000:1, can be challenging. One approach is to apply automated fitting routines. In this approach, combinations of 3 transitions can be created to form a "triple", which allows fitting of the A, B, and C rotational constants in a Watson-type Hamiltonian. On a standard desktop computer, with a target molecule of interest, a typical AUTOFIT routine takes 2-12 hours depending on the spectral density. A new approach is to utilize machine learning to train a computer to recognize the patterns (frequency spacing and relative intensities) inherit in rotational spectra and to identify the individual spectra in a raw broadband rotational spectrum. Here, recurrent neural networks have been trained to identify different types of rotational spectra and classify them accordingly. Furthermore, early results in applying convolutional neural networks for spectral object recognition in broadband rotational spectra appear promising. Perez et al. "Broadband Fourier transform rotational spectroscopy for structure determination: The water heptamer." Chem. Phys. Lett., 2013, 571, 1-15. Seifert et al. "AUTOFIT, an Automated Fitting Tool for Broadband Rotational Spectra, and Applications to 1-Hexanal." J. Mol. Spectrosc., 2015, 312, 13-21. Bishop. "Neural networks for pattern recognition." Oxford university press, 1995.

  11. Policy factors affecting broadband development in Poland

    DEFF Research Database (Denmark)

    Henten, Anders; Windekilde, Iwona Maria

    2014-01-01

    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...... will gradually change the previous balance of power. The specific problem of the Polish market is its very poor infrastructure development and the lack of competitors on the fixed market. This translates into limited access to services for end users particularly in the rural areas. A much lower level...... and discuss broadband access development in Poland and the policy factors influencing this development as well as to examine national strategies used to stimulate service and infrastructure competition in Poland. There are, indeed, many other factors affecting broadband development such as the income level...

  12. 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....

  13. 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 co....../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.......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...

  14. Design of metamaterial surfaces with broadband absorbance.

    Science.gov (United States)

    Wu, Chihhui; Shvets, Gennady

    2012-02-01

    A simple design paradigm for making broadband ultrathin plasmonic absorbers is introduced. The absorber's unit cell is composed of subunits of various sizes, resulting in nearly 100% absorbance at multiple adjacent frequencies and high absorbance over a broad frequency range. A simple theoretical model for designing broadband absorbers is presented. It uses a single-resonance model to describe the optical response of each subunit and employs the series circuit model to predict the overall response. Validity of the circuit model relies on short propagation lengths of the surface plasmons.

  15. 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.

  16. Temperature-independent broadband silicon modulator

    Science.gov (United States)

    Yi, H. X.; Li, T. T.; Zhang, J. L.; Wang, X. J.; Zhou, Z.

    2015-04-01

    We demonstrate a 20 Gb/s temperature-independent silicon modulator based on symmetrical Mach-Zehnder Interferometer. The MMI coupler was used as splitter/combiner in symmetrical MZI for balanced propagation. The ±15 °C temperature-independent eye diagrams were measured at 10 Gb/s with over 15 dB extinction ratio. Based on over 30 nm flat optical bandwidth, the broadband modulation was demonstrated from 1530 nm to 1560 nm. The temperature-independent broadband silicon modulator is adaptable to interconnection and communication systems in practice.

  17. Graphical programming for broadband pulse NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Belmonte, S.B. [Universidade do Estado (UERJ), Rio de Janeiro, RJ (Brazil). Dept. de Engenharia Eletronica; Oliveira, I.S.; Guimaraes, A.P. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)

    1997-12-31

    In a broadband pulsed nuclear magnetic resonance (NMR) spectrometer we often need to sweep the excitation frequency over a wide range, and acquire the spin echo components in quadrature for further spectral analysis. Computer languages such as C or Pascal have been traditionally applied to the development of software control of laboratory equipment, and consequently, the automatization of NMR experiments. However, the use of graphical languages have proved to be a flexible and convenient way for experiment and data acquisition control. In our application we use the graphical language Labview for the automatic control of a broadband pulse NMR spectrometer, dedicated to the study of magnetic metal systems. (author) 2 refs., 2 figs.

  18. 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 Denmark is doing well in most international comparisons, but retail prices are still relatively high and connection speeds are lower than the best performing countries. In terms of households, approximately three quarters have broadband access. Denmark - and a number of other countries as well - has thus...

  19. Polarization insensitive, broadband terahertz metamaterial absorber.

    Science.gov (United States)

    Grant, James; Ma, Yong; Saha, Shimul; Khalid, Ata; Cumming, David R S

    2011-09-01

    We present the simulation, implementation, and measurement of a polarization insensitive broadband resonant terahertz metamaterial absorber. By stacking metal-insulator layers with differing structural dimensions, three closely positioned resonant peaks are merged into one broadband absorption spectrum. Greater than 60% absorption is obtained across a frequency range of 1.86 THz where the central resonance frequency is 5 THz. The FWHM of the device is 48%, which is two and half times greater than the FWHM of a single layer structure. Such metamaterials are promising candidates as absorbing elements for bolometric terahertz imaging.

  20. Techno-Economics of Residential Broadband Deployment

    DEFF Research Database (Denmark)

    Sigurdsson, Halldor Matthias

    2007-01-01

    og kombinerer en solid teknisk viden om telenet og tjenester med økonomisk teori og teori for regulering af telekommunikation. På grundlag heraf opstilles en tekno-økonomisk omkostningsmodel, der simulerer kapitaludgifter og ydelser. Som et særligt element i modellen benyttes spilteori til......-Economics of Residential Broadband Deployment. It investigates the current market situation of broadband services, where the electricity companies challenge the incumbent telecom operators by extensive deployment of optical fibres to the end users. Very often the old telecom operators have a well-developed infrastructure...

  1. VT Wireless 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...

  2. 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...

  3. 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...

  4. 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...

  5. 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...

  6. VT Wireline 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...

  7. VT Detailed 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...

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  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 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...

  14. 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...

  15. 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...

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. VT Public Locations of Broadband Data - 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...

  1. 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...

  2. 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...

  3. 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...

  4. 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...

  5. 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...

  6. 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...

  7. 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...

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  12. 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...

  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 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...

  16. 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...

  17. 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...

  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 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...

  20. VT DSL 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...

  1. VT Cable 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...

  2. 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...

  3. Migration factors among broadband services: Panel data analysis

    OpenAIRE

    Shinohar, Sobee; Akematsu, Yuji; Tsuji, Masatsugu

    2012-01-01

    Providing nationwide deployment of broadband services has become an important national agenda. The U.S. announced a National Broadband Plan and EU a Digital Agenda for Europe, both of which aim at providing access to 100 Mbps broadband services by 2020 to substantial numbers of households. The purpose of this paper is to analyze the migration factors among broadband services, namely CATV (BB), DSL and FTTx, in OECD 30 countries. In so doing, we focus especially on migration from CATV (BB) and...

  4. Broadband Grounded Vertical Antennas for 30-180 MHZ (VHF)

    Science.gov (United States)

    2013-10-18

    antennas are well known for their broadband gain (monocone, bicone ) but are never combined with a monopole. An eccentric combination of broadband...DATES COVERED 00-00-2014 to 00-00-2014 4. TITLE AND SUBTITLE Broadband Grounded Vertical Antennas For 30-180 MZH (VHF) 5a. CONTRACT NUMBER 5b...18 Attorney Docket No. 102536 1 of 17 BROADBAND GROUNDED VERTICAL ANTENNAS FOR 30-180 MHZ (VHF) STATEMENT OF GOVERNMENT INTEREST

  5. Broadband: An Insight and Its Benefits | Devardhi | Science ...

    African Journals Online (AJOL)

    It is viewed by some as a double-edged sword: networking could promote economic development, yet electronic commerce also has the potential to displace local businesses. The paper focuses on defining broadband, identifying and assessing the benefits of broadband technologies. Although broadband technologies are ...

  6. 75 FR 36071 - Framework for Broadband Internet Service

    Science.gov (United States)

    2010-06-24

    ... COMMISSION Framework for Broadband Internet Service AGENCY: Federal Communications Commission. ACTION: Notice..., broadband Internet service. Recent developments--including a decision of the United States Court of Appeals... broadband Internet service. DATES: Comments must be submitted by July 15, 2010, and reply comments must be...

  7. Modelling and control of broadband traffic using multiplicative ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Modelling of broadband network traffic has emerged as an active area in the last decade. This has been primarily ... that broadband network traffic exhibits statistical self-similarity triggered off an immense volume of ...... with CAC control techniques and adaptive prediction of delay for bandwidth management in broadband ...

  8. 77 FR 36903 - Accelerating Broadband Infrastructure Deployment

    Science.gov (United States)

    2012-06-20

    ... and wireless broadband infrastructure. The Federal Government controls nearly 30 percent of all land... their respective agencies, in consultation with the Director of the Office of Science and Technology... of all application and other requirements; ensuring consistent interpretation and application of all...

  9. Catalyzing Broadband Internet in Africa | IDRC - International ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    This project aims to inform policies that help marginalized groups in Africa, such as women and the poor, to take advantage of the social and economic opportunities of broadband Internet. Internet access is critical for social and economic development in developing countries. According to a 2009 World Bank study, a 10% ...

  10. Broadband Minimum Variance Beamforming for Ultrasound Imaging

    DEFF Research Database (Denmark)

    Holfort, Iben Kraglund; Gran, Fredrik; Jensen, Jørgen Arendt

    2009-01-01

    A minimum variance (MV) approach for near-field beamforming of broadband data is proposed. The approach is implemented in the frequency domain, and it provides a set of adapted, complex apodization weights for each frequency subband. The performance of the proposed MV beamformer is tested on simu...

  11. 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.

  12. 75 FR 10455 - Broadband Initiatives Program

    Science.gov (United States)

    2010-03-08

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF AGRICULTURE Rural Utilities Service RIN 0572-ZA01 Broadband Initiatives Program AGENCY: Rural Utilities Service... fraud, waste and abuse, contact [email protected] for BIP. You may obtain additional...

  13. The broadband debate: A documentary research on the broadband policy in Australia

    OpenAIRE

    Li, Grace

    2011-01-01

    Against a current trend of investing in the next generation networks (NGNs) by using public funds, the Australian government has recently initiated a so-called National Broadband Networks (NBN) project to invest up to AUD$36 billion tax payer's money on building a national wide fibre broadband network aiming to cover 93 per cent Australian by 2020. As being the most costly infrastructure-building project in Australian history, the NBN project will use a public-private-partnership as the instr...

  14. 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

  15. 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.

  16. High-Resolution Broadband Spectral Interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Erskine, D J; Edelstein, J

    2002-08-09

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

  17. Broadband active electrically small superconductor antennas

    Science.gov (United States)

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

    2017-10-01

    A new type of broadband active electrically small antenna (ESA) based on superconducting quantum arrays (SQAs) has been proposed and developed. These antennas are capable of providing both sensing and amplification of broadband electromagnetic signals with a very high spurious-free dynamic range (SFDR)—up to 100 dB (and even more)—with high sensitivity. The frequency band can range up to tens of gigahertz, depending on Josephson junction characteristic frequency, set by fabrication. In this paper we review theoretical and experimental studies of SQAs and SQA-based antenna prototypes of both transformer and transformer-less types. The ESA prototypes evaluated were fabricated using a standard Nb process with critical current density 4.5 kA cm-2. Measured device characteristics, design issues and comparative analysis of various ESA types, as well as requirements for interfaces, are reviewed and discussed.

  18. 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.

  19. 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)

  20. The design of broadband radar absorbing surfaces

    OpenAIRE

    Go, Han Suk

    1990-01-01

    Approved for public release, distribution unlimited There has been a growing and widespread interest in radar-absorbing material technology. As the name implies, radar absorbing materials or RAM's are coatings whose electric and magnetic properties have been selected to allow the absorption of microwave energy at discrete or broadband frequencies. In military applications low radar cross section (RCS) of a vehicle may be required in order to escape detection while a covert mission is being...

  1. Switched Broadband Services For The Home

    Science.gov (United States)

    Sawyer, Don M.

    1990-01-01

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

  2. 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.

  3. Rail-based Broadband Synthetic Aperture Ocean Measurement System

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Enables collection of broadband acoustic scattering databases where acoustic sources and receivers can be translated on a precise linear path under program...

  4. Broadband low‐frequency electromagnetic waves in the inner magnetosphere

    National Research Council Canada - National Science Library

    Chaston, C. C; Bonnell, J. W; Kletzing, C. A; Hospodarsky, G. B; Wygant, J. R; Smith, C. W

    2015-01-01

    A prominent yet largely unrecognized feature of the inner magnetosphere associated with particle injections, and more generally geomagnetic storms, is the occurrence of broadband electromagnetic field...

  5. Analysis of United States’ Broadband Policy

    Science.gov (United States)

    2007-03-01

    of webcams . Today there is a much greater chance that someone working in the corporate sector is working or keeping up to date with their office...all American adults had high-speed Internet connections at home in the United States. In March 2005, that number was only 30 percent.47 Many new...Project’s combined January-March tracking survey of 4,402 adults ; 1,265 were home broadband users. 2006 data comes from the Pew Internet Project’s February

  6. Ultra-broadband microwave metamaterial absorber

    Science.gov (United States)

    Ding, Fei; Cui, Yanxia; Ge, Xiaochen; Jin, Yi; He, Sailing

    2012-03-01

    A microwave ultra-broadband polarization-independent metamaterial absorber is demonstrated. It is composed of a periodic array of metal-dielectric multilayered quadrangular frustum pyramids. These pyramids possess resonant absorption modes at multi-frequencies, of which the overlapping leads to the total absorption of the incident wave over an ultra-wide spectral band. The experimental absorption at normal incidence is above 90% in the frequency range of 7.8-14.7 GHz, and the absorption is kept large when the incident angle is smaller than 60°. The experimental results agree well with the numerical simulation.

  7. Broad-band semiconductor optical amplifiers

    Energy Technology Data Exchange (ETDEWEB)

    Ding Ying [Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)]. E-mail: yingding@red.semi.ac.cn; Kan Qiang [Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China); Wang Junling [Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing 100044 (China); Pan Jiaoqing [Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China); Zhou Fan [Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China); Chen Weixi [School of Physics, Peking University, Beijing 100871 (China); Wang Wei [Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)

    2007-01-15

    Broad-band semiconductor optical amplifiers (SOAs) with different thicknesses and thin bulk tensile-strained active layers were fabricated and studied. Amplified spontaneous emission (ASE) spectra and gain spectra of SOAs were measured and analyzed at different CW biases. A maximal 3 dB ASE bandwidth of 136 nm ranging from 1480 to 1616 nm, and a 3 dB optical amplifier gain bandwidth of about 90 nm ranging from 1510 to 1600 nm, were obtained for the very thin bulk active SOA. Other SOAs characteristics such as saturation output power and polarization sensitivity were measured and compared.

  8. Bioinspired irregularly chirped broadband reflecting multilayers

    Science.gov (United States)

    Chiadini, Francesco; Fiumara, Vincenzo; Scaglione, Antonio

    2017-08-01

    Dielectric multilayers consisting of alternating layers of two different materials with thicknesses irregularly decreasing with depth in the structure are included in the cuticle of some beetles whose shell exhibits broadband reflection in the optical wavelength range. Emulating these structures, we propose and numerically analyze irregularly chirped dielectric multilayers. Analysis was performed using a dedicated genetic algorithm (GA) that searches for the multilayer configurations maximizing the reflection for normal incidence over a large wavelength range. We found that the GA leads to the irregularly chirped reflectors that significantly outperform the regularly chirped ones proposed and analyzed in the literature.

  9. Broadband Planar 5:1 Impedence Transformer

    Science.gov (United States)

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

    2015-01-01

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

  10. Broadband slant linearly polarized biconical antenna

    Science.gov (United States)

    Lakshminarayana, D.; Prasad, R. V. H.; Murthy, T. G. K.

    1993-06-01

    A broadband biconical antenna with a slant linear polarizer, operating over 2-26 GHz range was designed and fabricated. The results of tests are presented, including the return loss plot of the antenna, radiation patterns at 2, 10, and 26 GHz for vertical and horizontal polarizations in azimuth and elevation planes, and curves indicating the elevation beam-width and gain of the antenna vs. frequency. The antenna gives an omni deviation of +/- 3 dB over 2-26 GHz. It is highly compact, and thus is suitable for systems where space requirements are very stringent.

  11. 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...

  12. Broadband bright twin beams and their upconversion

    Science.gov (United States)

    Chekhova, Maria V.; Germanskiy, Semen; Horoshko, Dmitri B.; Kitaeva, Galiya Kh.; Kolobov, Mikhail I.; Leuchs, Gerd; Phillips, Chris R.; Prudkovskii, Pavel A.

    2018-02-01

    We report on the observation of broadband (40 THz) bright twin beams through high-gain parametric down-conversion in an aperiodically poled lithium niobate crystal. The output photon number is shown to scale exponentially with the pump power and not with the pump amplitude, as in homogeneous crystals. Photon-number correlations and the number of frequency/temporal modes are assessed by spectral covariance measurements. By using sum-frequency generation on the surface of a non-phasematched crystal, we measure a cross-correlation peak with the temporal width 90 fs.

  13. Broadband for all closing the infrastructure gap

    CSIR Research Space (South Africa)

    Roux, K

    2015-10-01

    Full Text Available ” • World Bank on economic impact of broadband: The “1.38% factor” in GDP growth • “The impact of South Africa Connect on jobs and the economy”, Dr R Katz, 2013 • Investment in network construction • Economic “spill-overs” • Multifactor... gaps Province Weighted Gap (k- people.km) % Average Gap Eastern Cape 25 714 25% 3.92 km KwaZulu-Natal 23 393 23% 2.28 km Limpopo 17 265 17% 3.19 km North West 11 513 11% 3.28 km Gauteng...

  14. Peramalan Pengguna Broadband di Indonesia [Forecasting of Broadband Users in Indonesia

    Directory of Open Access Journals (Sweden)

    Azwar Aziz

    2016-07-01

    Full Text Available Negara Indonesia memiliki peluang yang sangat besar untuk merealisasikan potensi pitalebar, mengingat Indonesia memiliki jumlah penduduk 253 juta orang dan pengguna internet 88,1 juta orang pada tahun 2014. Di sisi lain sektor komunikasi (salah satunya termasuk telekomunikasi merupakan satu-satunya sektor yang secara konsisten memberikan kontribusi pertumbuhan terhadap Pendapatan Domestik Bruto (PDB sebesar dua angka (double digit. Kemudian peran penting pemerintah adalah selalu mengantisipasi dalam membuat regulasi telekomunikasi, salah satu nya untuk mempercepat penggelaran prasarana pitalebar, seperti menerbitkan Peraturan Presiden RI. Nomor 96 Tahun 2014 tentang Rencana Pitalebar Indonesia 2014 – 2019.  Secara riil pembangunan jaringan pitalebar di Indonesia masih dilakukan di kota-kota besar, mengingat pengguna telekomunikasi sebagian besar berada di kota-kota besar. Selain itu perangkat hanset atau handphone, ketersediaan di pasaran masih terbatas dan harganya masih mahal. Kajian ini menggunakan metodologi penelitian kuantitatif dengan menghitung peramalan dan kualitatif, dengan melakukan observasi atau pengamatan langsung ke lapangan kepada perusahaan Telkom, Telkomsel, XL Axiata dan Indosat. Selanjutnya hasil penelitian ini diperoleh lima faktor yang mempengaruhi penggunaan pitalebar yaitu jumlah penduduk, produk domestik bruto, pendapatan per kapita, laju pertumbuhan ekonomi dan inflasi, dan laju penetrasi. Selain itu, hasil pitalebar menunjukkan pengguna pitalebar lima tahun kedepan selalu meningkat.*****Indonesia has a tremendous opportunity to implement the potential of broadband, as Indonesia has a population of 253 million people and 88.1 million Internet users in 2014. On the other hand, the communication sector (one of them including telecommunications is the only sector that is consistently contributed to the growth of Gross Domestic Product (GDP as many as two numbers (double-digit. Then the important role of government is

  15. 76 FR 23812 - Reliability and Continuity of Communications Networks, Including Broadband Technologies; Effects...

    Science.gov (United States)

    2011-04-28

    ... they begin to deploy Smart Grid. Hospitals and healthcare providers can leverage broadband technologies... COMMISSION Reliability and Continuity of Communications Networks, Including Broadband Technologies; Effects... broadband technologies. 4. Today's increasingly interconnected world is one in which communications services...

  16. Reflective afocal broadband adaptive optics scanning ophthalmoscope

    Science.gov (United States)

    Dubra, Alfredo; Sulai, Yusufu

    2011-01-01

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

  17. 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.

  18. Broadband acoustic properties of a murine skull

    Science.gov (United States)

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

    2016-03-01

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

  19. The design of broadband radar absorbing surfaces

    Science.gov (United States)

    Suk, Go H.

    1990-09-01

    There has been a growing and widespread interest in radar absorbing material technology. As the name implies, radar absorbing materials or RAM's are coatings whose electric and magnetic properties have been selected to allow the absorption of microwave energy at discrete or broadband frequencies. In military applications low radar cross section (RCS) of a vehicle may be required in order to escape detection while a covert mission is being carried on. These requirements have led to the very low observable or stealth technology that reduces the probability of detection of an aircraft. The design of radar absorbing materials is limited by constraints on the allowable volume and weight of the surface coating, and it is difficult to design a broadband radar absorbing structure in limited volume. This thesis investigates the use of lossy dielectric materials of high dielectric permittivity in multilayer composites for the production of low radar cross section (RCS). The analysis is done by computing the plane wave reflection coefficient at the exterior surface of the composite coating by means of a computer program which selects layer parameters which determine low reflection coefficients for electromagnetic radiation under constraint of limited layer thickness as well as maximum frequency bandwidth.

  20. Reliability monitoring of broadband access networks

    Directory of Open Access Journals (Sweden)

    Perlicki Krzysztof

    2017-06-01

    Full Text Available One of the critical issues for broadband accesss is how to test the access network infrastructure and quality of optical signal. The installation and powering up of an optical fiber access networks requires measurement techniques for verifying the link has been configured properly and that its constituent components are functioning correctly. Maintenance functions for a broadband optical access network are classified in two main categories: preventive maintenance and post-fault maintenance. The first one consists of: surveillance (to detect degradation in optical fiber components, or any other anomalous condition not preventing the signal transmission,, testing (to measure and locate any detected degradation or anomalous condition and control (fiber identification and fiber transfer to allow the testing of the link.. In turn second one consisits of: surveillance (to detect alarms or trouble reports and activate a procedure for restoration, testing (to locate the fault and/or verify the carrier performances after the restoration and remedy (fiber identification, fiber repair or fiber transfer to restore the link.

  1. Broadband Adoption and Poverty: Evidence and New Research ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Broadband Adoption and Poverty: Evidence and New Research Directions from Latin America. Development luminaries like Jeffrey Sachs and Muhammad Yunus espouse the importance of broadband networks for promoting development. But where's the evidence to support the theory? Despite a strong national and ...

  2. Techno-economic evaluation of broadband access technologies

    DEFF Research Database (Denmark)

    Sigurdsson, Halldór Matthias; Skouby, Knud Erik

    2005-01-01

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

  3. Wireless Fidelity (Wi-Fi) Broadband Network Technology: An ...

    African Journals Online (AJOL)

    ... coverage, while Wi-Fi can be integrated with WiMAX networks to provide Internet connectivity to mobile Wi-Fi users. This paper explores the Wi-Fi broadband wireless network technology, its uses, advantages and disadvantages, comparison with other broadband wireless networks and integration with WiMAX network.

  4. 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…

  5. 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...

  6. Analisis Perkembangan Internet Broadband di Daerah Perbatasan Sulawesi Utara

    Directory of Open Access Journals (Sweden)

    Riva'atul Adaniah Wahab

    2016-12-01

    Full Text Available Adopsi teknologi internet broadband dapat memberikan dampak ekonomi bagi masyarakat perbatasan. Karenanya pemerataan pembangunan internet broadband di wilayah  ini harus segera diwujudkan. Penelitian deskriptif kuantitatif ini dilaksanakan di wilayah perbatasan Provinsi Sulawesi Utara untuk mengetahui kondisi aspek supply dan demand perkembangan internet broadband di wilayah tersebut. Berdasarkan hasil penelitian, dapat disimpulkan bahwa dari aspek supply, kondisi infrastruktur masih sangat kurang, ketersediaan layanan internet broadband berkualitas tinggi dengan tarif rendah juga masih sulit diwujudkan. Dari aspek demand, stigma atau persepsi masyarakat bahwa internet tidak penting menjadi salah satu faktor penyebab tidak memiliki akses internet. Adapun hambatan yang paling dominan adalah ketidakpahaman dalam penggunaan internet. Faktor ini juga menjadi mendasari literasi internet broadband masyarakat pada level 0 yaitu  tidak peduli akan pentinya internet. Menanggapai kondisi ini, penyusunan dan penetapan kebijakan serta regulasi seperti QoS layanan, tarif interkoneksi, infrastructure sharing dibuat untuk menyediakan internet broadband berkualitas tinggi dengan harga murah. Selain itu distribusi perangkat mobile berharga murah (smartphone juga perlu didorong dengan penerapan TKDN untuk produksi perangkat. Tidak kalah pentingnya adalah peningkatan literasi internet broadband masyarakat melalui sosialisasi atau pelatihan baik formal maupun nonformal. Abstract   Adoption of internet broadband internet can provide the economic impact for border communities. Hence equitable development of internet broadband in the region should be immediately implemented. This quantitative descriptive study was conducted in the border region of North Sulawesi to determine the condition of supply and demand aspects of the development of internet broadband. Based on the results, it can be concluded that from the aspect of supply, the condition of the

  7. Broadband Acoustic Cloak for Ultrasound Waves

    Science.gov (United States)

    Zhang, Shu; Xia, Chunguang; Fang, Nicholas

    2011-01-01

    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 (˜6dB/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. Piezoelectric energy harvesting from broadband random vibrations

    Science.gov (United States)

    Adhikari, S.; Friswell, M. I.; Inman, D. J.

    2009-11-01

    Energy harvesting for the purpose of powering low power electronic sensor systems has received explosive attention in the last few years. Most works using deterministic approaches focusing on using the piezoelectric effect to harvest ambient vibration energy have concentrated on cantilever beams at resonance using harmonic excitation. Here, using a stochastic approach, we focus on using a stack configuration and harvesting broadband vibration energy, a more practically available ambient source. It is assumed that the ambient base excitation is stationary Gaussian white noise, which has a constant power-spectral density across the frequency range considered. The mean power acquired from a piezoelectric vibration-based energy harvester subjected to random base excitation is derived using the theory of random vibrations. Two cases, namely the harvesting circuit with and without an inductor, have been considered. Exact closed-form expressions involving non-dimensional parameters of the electromechanical system have been given and illustrated using numerical examples.

  9. Broadband Approximations for Doubly Curved Reflector Antenna

    Directory of Open Access Journals (Sweden)

    V. Schejbal

    2010-12-01

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

  10. 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....... The first part gives a brief description of some of the existing protocols for routing and controlling resources, such as RSVP, OSPF, BGP, PNNI, etc. The remaining part concerns the following two fundamentally different approaches to resource management etc.: - Software agents - Simulated ants...... at developing a demonstration platform, where software agents handled virtually all aspects of controlling an ATM-based network. In the beginning of the part about simulated ants it is explained how scientists believe ants in nature find their way through the environment between their nest and food sources...

  11. Broadband optical characterization of material properties

    DEFF Research Database (Denmark)

    Nielsen, Otto Højager Attermann

    the applicability of optical techniques for this purpose, the fermentation of milk into yogurt has been used as a model system. Studies have been conducted on commercially available products, but also of on-line measurement of the fermentation process. The second process is from the aquaculture industry...... to develop and investigate the applicability of optical broadband characterization techniques in industrially relevant production process. Both combined broad and high resolution techniques have the potential to provide important information on scattering properties related to particle size distributions......, as well as details of the absorption spectrum which relate to chemical composition. The thesis focuses on two production process from the food industry. The first process is from the dairy industry where discrimination between chemical and structural properties is of importance. To explore...

  12. 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.

  13. Terahertz broadband polarization converter based on metamaterials

    Science.gov (United States)

    Li, Yonghua; Zhao, Guozhong

    2018-01-01

    Based on the metamaterial composed of symmetrical split resonant ring, a broadband reflective terahertz polarization converter is proposed. The numerical simulation shows that it can rotate the polarization direction of linear polarized wave 90° in the range of 0.7-1.8THz and the polarization conversion ratio is over 90%. The reflection coefficient of the two electric field components in the diagonal direction is the same and the phase difference is 180° ,which leads to the cross-polarization rotation.In order to further study the physical mechanism of high polarization conversion, we analyze the surface current distribution of the resonant ring. The polarization converter has potential applications in terahertz wave plate and metamaterial antenna design.

  14. Broadband graphene-based metamaterial absorbers

    Science.gov (United States)

    Liu, Chang; Qi, Limei; Zhang, Xu

    2018-01-01

    In this paper, a new type of broadband tunable metamaterial absorber is proposed. The structure consists of a single-layer ring graphene and a metal ground plane separated by a dielectric spacer. The graphene rings are connected each other to be easily tuned by the voltage. In addition, this absorber is polarization-independent at normal incidence due to the symmetric pattern of the unit cell. Results reveal the bandwidth of 90% absorption reaches to 2.25 THz for a single-ring structure. The bandwidth of 90% absorption increases to 3.2 THz by combining two similar rings with different sizes in one unit cell. The physical mechanism of the single-ring and dual-ring absorbers are given based on the impedance matching theory.

  15. Digital broadband linearization of optical links.

    Science.gov (United States)

    Lam, Daniel; Fard, Ali M; Buckley, Brandon; Jalali, Bahram

    2013-02-15

    We present a digital postprocessing linearization technique to efficiently suppress dynamic distortions added to a wideband signal in an analog optical link. Our technique achieves up to 35 dB suppression of intermodulation distortions over multiple octaves of signal bandwidth. In contrast to conventional linearization methods, it does not require excessive analog bandwidth for performing digital correction. This is made possible by regenerating undesired distortions from the captured output, and subtracting it from the distorted digitized signal. Moreover, we experimentally demonstrate a record spurious-free dynamic range of 120 dB·Hz(2/3) over a 6 GHz electrical signal bandwidth. While our digital broadband linearization technique advances state-of-the-art optical links, it can also be applied to other nonlinear dynamic systems.

  16. 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.

  17. A compact broadband nonsynchronous noncommensurate impedance transformer

    DEFF Research Database (Denmark)

    Zhurbenko, Vitaliy; Kim, Kseniya; Narenda, Kumar

    2012-01-01

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

  18. 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...... for propagation of the light in at least a first mode along a longitudinal axis (102, 202, 302) of the amplifier (100, 200, 300, 400, 800) in a propagation direction (103, 203, 303), and wherein the waveguide region (101, 201, 301, 401, 801) comprises a gain region (104, 204, 304, 404, 804) for amplifying......, 301, 401, 801) increases along the longitudinal axis (102, 202, 302), and wherein the ratio between the width (106, 206, 306) of the waveguide region (101, 201, 301, 401, 801) and the width (107, 207, 307) of the gain region (104, 204, 304, 404, 804) increases along the longitudinal axis (102, 202...

  19. Broadband sound pressure enhancement in passive metafluids

    Science.gov (United States)

    Popa, Bogdan-Ioan

    2017-09-01

    Acoustic sensors operating in lossy environments, such as water, require significant sensitivity to overcome the sound attenuation in the environment and thus see farther. We show here that a surprisingly large class of passive fluids has the ability to enhance the sound pressure propagating inside them without employing active actuation. Specifically, the general requirements for this remarkable property are fluid impedance higher than the impedance of the environment and negligible insertion loss as sound propagates from the environment into the high impedance fluid. We demonstrate the pressure enhancing effect by designing a broadband isotropic metafluid that increases the pressure of sound waves impinging from water. We validate the design in numerical simulations showing that significant sound pressure level increases are achievable in realistic metafluid structures in large bandwidths covering several octaves. Our approach opens up unexplored avenues towards improving acoustic transducer sensitivity, which is critical in applications, such as medical ultrasound imaging, sonar, and acoustic communications.

  20. Broadband optical modulators based on graphene supercapacitors.

    Science.gov (United States)

    Polat, Emre O; Kocabas, Coskun

    2013-01-01

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

  1. 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.

  2. Broadband graphene-based metamaterial absorbers

    Directory of Open Access Journals (Sweden)

    Chang Liu

    2018-01-01

    Full Text Available In this paper, a new type of broadband tunable metamaterial absorber is proposed. The structure consists of a single-layer ring graphene and a metal ground plane separated by a dielectric spacer. The graphene rings are connected each other to be easily tuned by the voltage. In addition, this absorber is polarization-independent at normal incidence due to the symmetric pattern of the unit cell. Results reveal the bandwidth of 90% absorption reaches to 2.25 THz for a single-ring structure. The bandwidth of 90% absorption increases to 3.2 THz by combining two similar rings with different sizes in one unit cell. The physical mechanism of the single-ring and dual-ring absorbers are given based on the impedance matching theory.

  3. Patient portals and broadband internet inequality.

    Science.gov (United States)

    Perzynski, Adam T; Roach, Mary Joan; Shick, Sarah; Callahan, Bill; Gunzler, Douglas; Cebul, Randall; Kaelber, David C; Huml, Anne; Thornton, John Daryl; Einstadter, Douglas

    2017-09-01

    Patient portals have shown potential for increasing health care quality and efficiency. Internet access and other factors influencing patient portal use could worsen health disparities. Observational study of adults with 1 or more visits to the outpatient clinics of an urban public health care system from 2012 to 2015. We used mixed effects logistic regression to evaluate the association between broadband internet access and (1) patient portal initiation (whether a patient logged in at least 1 time) and (2) messaging, controlling for demographic and neighborhood characteristics. There were 243 248 adults with 1 or more visits during 2012-2015 and 70 835 (29.1%) initiated portal use. Portal initiation was 34.1% for whites, 23.4% for blacks, and 23.8% for Hispanics, and was lower for Medicaid (26.5%), Medicare (23.4%), and uninsured patients (17.4%) than commercially insured patients (39.3%). In multivariate analysis, both initiation of portal use (odds ratio [OR] = 1.24 per quintile, 95% confidence interval [CI], 1.23-1.24, P  internet access. The majority of adults with outpatient visits to a large urban health care system did not use the patient portal, and initiation of use was lower for racial and ethnic minorities, persons of lower socioeconomic status, and those without neighborhood broadband internet access. These results suggest the emergence of a digital divide in patient portal use. Given the scale of investment in patient portals and other internet-dependent health information technologies, efforts are urgently needed to address this growing inequality.

  4. Metropolitan area networks: a corner stone in the broadband era

    Science.gov (United States)

    Ghanem, Adel

    1991-02-01

    Deployment of Broadband ISDN is being influenced by both a market pull and a technology push. New broadband service opportunities exist in the business and residential sectors of the market place. It is envisioned that some customers will need connections directly to broadband switches because of the high bandwidth needed for their applications. At the same time Metropolitan Area Network (MAN) systems will serve those customers with bandwidth requirements less than or equal to 150 Mbps. A given MAN will have a geographical domain to serve where it will carry out the switching tasks within this domain. While MANs couldbe designed using differentarchitecturalconcepts the setofservices expected tobeprovidedby MANs could be equivalent to thelist ofservices thatwillbe supported by the targetbroadband network. This paperpositions MANs as a major building block for Broadband networks. It also examines the evolution process ofMANs as a needed step to assure the successful deployment of these new broadband services. 2. BISDN - OVERVIEW Broadband ISDN (BISDN) is being driven into existence by both a market pull as well as a technology push. Opportunities for new valueadded services are the prime market pull for future broadband networks. These services opportunities extend beyond simple voice and low speed data applications and cover both the residential and the business sectors of the market. It is noted for instance that business customers have growing needs for sophisticated telecommunication vehicles to support their

  5. Broadband infrared absorbers with stacked double chromium ring resonators

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Huixu; Stan, Liliana; Czaplewski, David A.; Gao, Jie; Yang, Xiaodong

    2017-01-01

    A broadband absorber in the infrared wavelength range from 1 μm up to 5 μm is designed and demonstrated with stacked double chromium ring resonators on a reflective chromium mirror. The near-perfect broadband absorption is realized by combining the multilayer impedance match in the short wavelength range and the double plasmonic resonances in the long wavelength range, which is illustrated with an equivalent circuit model for the impedance analysis. The broadband absorber is proved to be angle-insensitive and polarization-independent due to the geometrical symmetry. The thermal analysis for heat generation and temperature distributions inside the absorber structure is also investigated.

  6. 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...

  7. Fixed Broadband Deployment Data: June, 2016 Status V1

    Data.gov (United States)

    Federal Communications Commission — Version 1 reflects data filed by the March 1, 2016 filing deadline and any revisions made before February 10, 2017. All facilities-based broadband providers are...

  8. 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.

  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. Fixed Broadband Deployment Data: June, 2016 Status V2

    Data.gov (United States)

    Federal Communications Commission — This data contains status reports for June 2016, with revisions accepted through May 2017. All facilities-based broadband providers are required to file data with...

  11. Thermally tunable water-substrate broadband metamaterial absorbers

    Science.gov (United States)

    Pang, Yongqiang; Wang, Jiafu; Cheng, Qiang; Xia, Song; Zhou, Xiao Yang; Xu, Zhuo; Cui, Tie Jun; Qu, Shaobo

    2017-03-01

    The naturally occurring water has frequency dispersive permittivity at microwave frequencies and thus is a promising constituent material for broadband absorbers. Here, we develop water as the dielectric spacer in the substrate of metal-backed metamaterial (MM) absorbers. The designed substrate is a hybrid of water and a low-permittivity dielectric material. Such a design allows tight packaging of water and easy fabrication of the absorber. We obtain broadband absorption at temperatures of interest by designing the hybrid substrate and MM inclusions. Additionally, the absorption performance of the water-substrate MM absorbers could be tunable according to the environment temperature. We experimentally demonstrate the broadband and thermally tunable absorption performance. We expect that water could replace dielectric layers in other structural MM absorbers to achieve the broadband and thermally tunable absorption performance.

  12. A novel ultrathin and broadband microwave metamaterial absorber

    Science.gov (United States)

    Wang, Bei-Yin; Liu, Shao-Bin; Bian, Bo-Rui; Mao, Zhi-Wen; Liu, Xiao-Chun; Ma, Ben; Chen, Lin

    2014-09-01

    In this paper, the design, simulation, fabrication, and measurement of an ultrathin and broadband microwave metamaterial absorber (MMA) based on a double-layer structure are presented. Compared with the prior work, our structure is simple and polarization insensitive. The broadband MMA presents good absorption above 90 % between 8.85 GHz and 14.17 GHz , with a full width at half maximum (FWHM) absorption bandwidth of 6.77 GHz and a relative FWHM absorption bandwidth of 57.3 % . Moreover, the structure has a thickness of 1.60 mm (only λ/20 at the lowest frequencies). The experimental results show excellent absorption rates which are in good correspondence with the simulated results. The broadband absorber is promising candidates as absorbing elements in scientific and technical applications because of its broadband absorption and polarization insensitive.

  13. 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

  14. Tunable and Broadband Differential Phase Sections in Terahertz Frequency Range

    Science.gov (United States)

    Kosiak, O. S.; Bezborodov, V. I.; Kuleshov, Ye. M.; Nesterov, P. K.

    2016-12-01

    Purpose: Studying the quasioptical tunable and broadband differential phase section (DPS) consisting of several birefringent elements (BE) on the basis of form birefringence effect. Design/methodology/approach: Using the polarization scattering matrix method, the impact of the mutual rotation axis of anisotropy of several BE by the amount of phase shift and the position of the plane of anisotropy of resulting DPS is considered. Findings: The DPS tunable in a wide range are shown to be possibly implemented in the case of quarter- wave DPS of two, and in the case of half-wave DPS of three, identical non-tunable BE. The analysis has shown to the possibility of creating a broadband quarter-wave and half-wave DPS. Conclusions: Experimental research has confirmed the possibility of constructing a tunable and broadband DPS. On this basis, tunable and broadband polarization converters, rotators of polarization plane, polarization phase shifters and frequency shifters in the terahertz frequency range can be created.

  15. 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+...

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

    Science.gov (United States)

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

    2014-12-17

    A high-temperature stable broadband plasmonic absorber is designed, fabricated, and optically characterized. A broadband absorber with an average high absorption of 95% and a total thickness of 240 nm is fabricated, using a refractory plasmonic material, titanium nitride. This absorber integrates both the plasmonic resonances and the dielectric-like loss. It opens a path for the interesting applications such as solar thermophotovoltaics and optical circuits. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Nonlinear envelope equation for broadband optical pulses in quadratic media

    CERN Document Server

    Conforti, Matteo; De Angelis, Costantino

    2010-01-01

    We derive a nonlinear envelope equation to describe the propagation of broadband optical pulses in second order nonlinear materials. The equation is first order in the propagation coordinate and is valid for arbitrarily wide pulse bandwidth. Our approach goes beyond the usual coupled wave description of $\\chi^{(2)}$ phenomena and provides an accurate modelling of the evolution of ultra-broadband pulses also when the separation into different coupled frequency components is not possible or not profitable.

  18. Analysis of broadband services diffusion in OECD 30 countries: Focusing on open access obligations

    OpenAIRE

    Shinohara, Sobee; Akematsu, Yuji; Tsuji, Masatsugu

    2011-01-01

    Deployment of broadband for everyone has become a major policy objective in many countries, including Japan and the U.S. Recently, the U.S. announced a National Broadband Plan which is aimed at providing 100 million households with access to 100 Mbps broadband services by 2020. The purpose of this paper is to conduct an empirical analysis to identify factors affecting broadband service diffusion in OECD 30 member countries. First, considering the ratios by broadband technologies, we categoriz...

  19. Developing a Broadband Adoption Model in the UK Context

    Science.gov (United States)

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

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

  20. Broadband properties of active galactic nuclei

    Science.gov (United States)

    Edelson, Richard Allen

    The broadband radio-infrared-optical-ultraviolet properties of active galactic nuclei are used to investigate the nature of the central engine and the surrounding environment. Optically selected quasars and Seyfert 1 galaxies tend to have relatively flat infrared spectra and low reddenings, while most Seyfert 2 galaxies and other dusty objects have steep infrared spectra and larger reddenings. The infrared spectra of most luminous radio-quiet active galaxies turn over near approx. 80 micron. It appears that the infrared spectra of most quasars and luminous Seyfert 1 galaxies are dominated by unreprocessed radiation from a synchrotron self-absorbed source of order a light day across, about the size of the hypothesized accretion disk. Seyfert 2 galaxies and other reddened objects have infrared spectra which appear to be dominated by thermal emission from warm dust, probably in the disk of the underlying galaxy. A broad emission feature, centered near 5 micron, is present in many luminous quasars and Seyfert 1 galaxies. Highly polarized objects (blazars) can be strongly variable at far infrared wavelengths over time scales of months. Seyfert galaxies tend to have steep radio spectra.

  1. Electronic resonances in broadband stimulated Raman spectroscopy

    Science.gov (United States)

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

    2016-01-01

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

  2. Broadband Vibration Attenuation Using Hybrid Periodic Rods

    Directory of Open Access Journals (Sweden)

    S. Asiri

    2008-12-01

    Full Text Available This paper presents both theoretically and experimentally a new kind of a broadband vibration isolator. It is a table-like system formed by four parallel hybrid periodic rods connected between two plates. The rods consist of an assembly of periodic cells, each cell being composed of a short rod and piezoelectric inserts. By actively controlling the piezoelectric elements, it is shown that the periodic rods can efficiently attenuate the propagation of vibration from the upper plate to the lower one within critical frequency bands and consequently minimize the effects of transmission of undesirable vibration and sound radiation. In such a system, longitudinal waves can propagate from the vibration source in the upper plate to the lower one along the rods only within specific frequency bands called the "Pass Bands" and wave propagation is efficiently attenuated within other frequency bands called the "Stop Bands". The spectral width of these bands can be tuned according to the nature of the external excitation. The theory governing the operation of this class of vibration isolator is presented and their tunable filtering characteristics are demonstrated experimentally as functions of their design parameters. This concept can be employed in many applications to control the wave propagation and the force transmission of longitudinal vibrations both in the spectral and spatial domains in an attempt to stop/attenuate the propagation of undesirable disturbances.

  3. Extreme-angle broadband metamaterial lens.

    Science.gov (United States)

    Kundtz, Nathan; Smith, David R

    2010-02-01

    For centuries, the conventional approach to lens design has been to grind the surfaces of a uniform material in such a manner as to sculpt the paths that rays of light follow as they transit through the interfaces. Refractive lenses formed by this procedure of bending the surfaces can be of extremely high quality, but are nevertheless limited by geometrical and wave aberrations that are inherent to the manner in which light refracts at the interface between two materials. Conceptually, a more natural--but usually less convenient--approach to lens design would be to vary the refractive index throughout an entire volume of space. In this manner, far greater control can be achieved over the ray trajectories. Here, we demonstrate how powerful emerging techniques in the field of transformation optics can be used to harness the flexibility of gradient index materials for imaging applications. In particular we design and experimentally demonstrate a lens that is broadband (more than a full decade bandwidth), has a field-of-view approaching 180 degrees and zero f-number. Measurements on a metamaterial implementation of the lens illustrate the practicality of transformation optics to achieve a new class of optical devices.

  4. Hollow plasmonic antennas for broadband SERS spectroscopy

    Directory of Open Access Journals (Sweden)

    Gabriele C. Messina

    2015-02-01

    Full Text Available 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.

  5. 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.

  6. A Broadband Ultrathin Nonlinear Switching Metamaterial

    Directory of Open Access Journals (Sweden)

    E. Zarnousheh Farahani

    2017-05-01

    Full Text Available In this paper, an ultrathin planar nonlinear metamaterial slab is designed and simulated. Nonlinearity is provided through placing diodes in each metamaterial unit cell. The diodes are auto-biased and activated by an incident wave. The proposed structure represents a broadband switching property between two transmission and reflection states depending on the intensity of the incident wave. High permittivity values are presented creating a near zero effective impedance at low power states, around the second resonant mode of the structure unit cell; as the result, the incident wave is reflected. Increasing the incident power to the level which can activate the loaded diodes in the structure results in elimination of the resonance and consequently a drop in the permittivity values near the permeability one as well as a switch to the transmission state. A full wave as well as a nonlinear simulations are performed. An optimization method based on weed colonization is applied to the unit cell of the metamaterial slab to achieve the maximum switching bandwidth. The structure represents a 24% switching bandwidth of a 10 dB reduction in the reflection coefficient.

  7. HCIT Broadband Contrast Performance Sensitivity Studies

    Science.gov (United States)

    Sidick, Erkin; Shaklan, Stuart; Balasubramanian, Kunjithapatham

    2012-01-01

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

  8. Ionomer Dynamics: Insights from Broadband Dielectric Spectroscopy

    Science.gov (United States)

    Runt, James

    2015-03-01

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

  9. 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.

  10. Broadband Spectral Investigations of Magnetar Bursts

    Science.gov (United States)

    Kırmızıbayrak, Demet; Şaşmaz Muş, Sinem; Kaneko, Yuki; Göğüş, Ersin

    2017-09-01

    We present our broadband (2-250 keV) time-averaged spectral analysis of 388 bursts from SGR J1550-5418, SGR 1900+14, and SGR 1806-20 detected with the Rossi X-ray Timing Explorer (RXTE) here and as a database in a companion web-catalog. We find that two blackbody functions (BB+BB), the sum of two modified blackbody functions (LB+LB), the sum of a blackbody function and a power-law function (BB+PO), and a power law with a high-energy exponential cutoff (COMPT) all provide acceptable fits at similar levels. We performed numerical simulations to constrain the best fitting model for each burst spectrum and found that 67.6% of burst spectra with well-constrained parameters are better described by the Comptonized model. We also found that 64.7% of these burst spectra are better described with the LB+LB model, which is employed in the spectral analysis of a soft gamma repeater (SGR) for the first time here, than with the BB+BB and BB+PO models. We found a significant positive lower bound trend on photon index, suggesting a decreasing upper bound on hardness, with respect to total flux and fluence. We compare this result with bursts observed from SGR and AXP (anomalous X-ray pulsar) sources and suggest that the relationship is a distinctive characteristic between the two. We confirm a significant anticorrelation between burst emission area and blackbody temperature, and find that it varies between the hot and cool blackbody temperatures differently than previously discussed. We expand on the interpretation of our results in the framework of a strongly magnetized neutron star.

  11. Broadband Spectral Investigations of Magnetar Bursts

    Energy Technology Data Exchange (ETDEWEB)

    Kırmızıbayrak, Demet; Şaşmaz Muş, Sinem; Kaneko, Yuki; Göğüş, Ersin, E-mail: demetk@sabanciuniv.edu [Faculty of Engineering and Natural Sciences, Sabancı University, Orhanlı Tuzla, Istanbul 34956 (Turkey)

    2017-09-01

    We present our broadband (2–250 keV) time-averaged spectral analysis of 388 bursts from SGR J1550−5418, SGR 1900+14, and SGR 1806−20 detected with the Rossi X-ray Timing Explorer ( RXTE ) here and as a database in a companion web-catalog. We find that two blackbody functions (BB+BB), the sum of two modified blackbody functions (LB+LB), the sum of a blackbody function and a power-law function (BB+PO), and a power law with a high-energy exponential cutoff (COMPT) all provide acceptable fits at similar levels. We performed numerical simulations to constrain the best fitting model for each burst spectrum and found that 67.6% of burst spectra with well-constrained parameters are better described by the Comptonized model. We also found that 64.7% of these burst spectra are better described with the LB+LB model, which is employed in the spectral analysis of a soft gamma repeater (SGR) for the first time here, than with the BB+BB and BB+PO models. We found a significant positive lower bound trend on photon index, suggesting a decreasing upper bound on hardness, with respect to total flux and fluence. We compare this result with bursts observed from SGR and AXP (anomalous X-ray pulsar) sources and suggest that the relationship is a distinctive characteristic between the two. We confirm a significant anticorrelation between burst emission area and blackbody temperature, and find that it varies between the hot and cool blackbody temperatures differently than previously discussed. We expand on the interpretation of our results in the framework of a strongly magnetized neutron star.

  12. Specdata: Automated Analysis Software for Broadband Spectra

    Science.gov (United States)

    Oliveira, Jasmine N.; Martin-Drumel, Marie-Aline; McCarthy, Michael C.

    2017-06-01

    With the advancement of chirped-pulse techniques, broadband rotational spectra with a few tens to several hundred GHz of spectral coverage are now routinely recorded. When studying multi-component mixtures that might result, for example, with the use of an electrical discharge, lines of new chemical species are often obscured by those of known compounds, and analysis can be laborious. To address this issue, we have developed SPECdata, an open source, interactive tool which is designed to simplify and greatly accelerate the spectral analysis and discovery. Our software tool combines both automated and manual components that free the user from computation, while giving him/her considerable flexibility to assign, manipulate, interpret and export their analysis. The automated - and key - component of the new software is a database query system that rapidly assigns transitions of known species in an experimental spectrum. For each experiment, the software identifies spectral features, and subsequently assigns them to known molecules within an in-house database (Pickett .cat files, list of frequencies...), or those catalogued in Splatalogue (using automatic on-line queries). With suggested assignments, the control is then handed over to the user who can choose to accept, decline or add additional species. Data visualization, statistical information, and interactive widgets assist the user in making decisions about their data. SPECdata has several other useful features intended to improve the user experience. Exporting a full report of the analysis, or a peak file in which assigned lines are removed are among several options. A user may also save their progress to continue at another time. Additional features of SPECdata help the user to maintain and expand their database for future use. A user-friendly interface allows one to search, upload, edit or update catalog or experiment entries.

  13. The relationship investigation between factors affecting demand for broadband and the level of satisfaction among broadband customers in the South East Coast of Sabah, Malaysia

    Science.gov (United States)

    Hashim, S. H. A.; Hamid, F. A.; Kiram, J. J.; Sulaiman, J.

    2017-09-01

    This paper aims to investigate the relationship between factors that affecting the demand for broadband and the level of satisfaction. Previous researchers have found that the adoption of broadband is greatly influenced by many factors. Thus, in this study, a self-administered questionnaire was developed to obtain the factors affecting demand for broadband among broadband customers as well as their level of satisfaction. Pearson correlation, one-way analysis of variance (ANOVA) and t-test were used for statistical interpretation of the relationship. This study shows that there are better relationships between several factors over demand for broadband and satisfaction level.

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

    Science.gov (United States)

    Peternel, Blaž Kos, Andrej

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

  15. Broadband low-frequency sound isolation by lightweight adaptive metamaterials

    Science.gov (United States)

    Liao, Yunhong; Chen, Yangyang; Huang, Guoliang; Zhou, Xiaoming

    2018-03-01

    Blocking broadband low-frequency airborne noises is highly desirable in lots of engineering applications, while it is extremely difficult to be realized with lightweight materials and/or structures. Recently, a new class of lightweight adaptive metamaterials with hybrid shunting circuits has been proposed, demonstrating super broadband structure-borne bandgaps. In this study, we aim at examining their potentials in broadband sound isolation by establishing an analytical model that rigorously combines the piezoelectric dynamic couplings between adaptive metamaterials and acoustics. Sound transmission loss of the adaptive metamaterial is investigated with respect to both the frequency and angular spectrum to demonstrate their sound-insulation effects. We find that efficient sound isolation can indeed be pursued in the broadband bi-spectrum for not only the case of the small resonator's periodicity where only one mode relevant to the mass-spring resonance exists, but also for the large-periodicity scenario, so that the total weight can be even lighter, in which the multiple plate-resonator coupling modes appear. In the latter case, the negative spring stiffness provided by the piezoelectric stack has been utilized to suppress the resonance-induced high acoustic transmission. Such kinds of adaptive metamaterials could open a new approach for broadband noise isolation with extremely lightweight structures.

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

    Science.gov (United States)

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

    2001-12-01

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

  17. Bio-inspired heterogeneous composites for broadband vibration mitigation

    Science.gov (United States)

    Chen, Yanyu; Wang, Lifeng

    2015-12-01

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

  18. Broadband minimum variance beamforming for ultrasound imaging.

    Science.gov (United States)

    Holfort, Iben Kraglund; Gran, Fredrik; Jensen, Jørgen Arendt

    2009-02-01

    A minimum variance (MV) approach for near-field beamforming of broadband data is proposed. The approach is implemented in the frequency domain, and it provides a set of adapted, complex apodization weights for each frequency subband. The performance of the proposed MV beamformer is tested on simulated data obtained using Field II. The method is validated using synthetic aperture data and data obtained from a plane wave emission. Data for 13 point targets and a circular cyst with a radius of 5 mm are simulated. The performance of the MV beamformer is compared with delay-and-sum (DS) using boxcar weights and Hanning weights and is quantified by the full width at half maximum (FWHM) and the peak-side-lobe level (PSL). Single emission {DS boxcar, DS Hanning, MV} provide a PSL of {-16, -36, -49} dB and a FWHM of {0.79, 1.33, 0.08} mm. Using all 128 emissions, {DS boxcar, DS Hanning, MV} provides a PSL of {-32, -49, -65} dB, and a FWHM of {0.63, 0.97, 0.08} mm. The contrast of the beamformed single emission responses of the circular cyst was calculated as {-18, -37, -40} dB. The simulations have shown that the frequency subband MV beamformer provides a significant increase in lateral resolution compared with DS, even when using considerably fewer emissions. An increase in resolution is seen when using only one single emission. Furthermore, the effect of steering vector errors is investigated. The steering vector errors are investigated by applying an error of the sound speed estimate to the ultrasound data. As the error increases, it is seen that the MV beamformer is not as robust compared with the DS beamformer with boxcar and Hanning weights. Nevertheless, it is noted that the DS does not outperform the MV beamformer. For errors of 2% and 4% of the correct value, the FWHM are {0.81, 1.25, 0.34} mm and {0.89, 1.44, 0.46} mm, respectively.

  19. Double-corrugated metamaterial surfaces for broadband microwave absorption

    Science.gov (United States)

    Pang, Yongqiang; Cheng, Haifeng; Zhou, Yongjiang; Wang, Jun

    2013-02-01

    Double-corrugated metamaterial surfaces are proposed to achieve broadband absorbers in the microwave region. The principal corrugation having a long period is made of hypo-corrugated metal structures filled with a dielectric medium. It is shown that the incident electromagnetic wave with a certain frequency can be strongly absorbed by the corrugation region where the height is about λ/4, with λ being the corresponding wavelength in the dielectric. Assembling various heights of corrugations together to form a graded corrugation surface can excite many distinct absorption modes and their overlapping with each other results in a broadband absorption. We experimentally demonstrate a broadband metamaterial absorber with more than 80% absorbance in the frequency range of 7.22-18.0 GHz which agrees well with the numerical simulation.

  20. Broadband planar multilayered absorbers tuned by VO2 phase transition

    Science.gov (United States)

    Peng, Hao; Ji, Chunhui; Lu, Lulu; Li, Zhe; Li, Haoyang; Wang, Jun; Wu, Zhiming; Jiang, Yadong; Xu, Jimmy; Liu, Zhijun

    2017-08-01

    The metal-insulator transition makes vanadium dioxide an attractive material for developing reconfigurable optoelectronic components. Here we report on dynamically tunable broadband absorbers consisting of planar multilayered thin films. By thermally triggering the phase transition of vanadium dioxide, the effective impedance of multilayered structures is tuned in or out of the condition of impedance matching to free-space, leading to switchable broadband absorptions. Two types of absorbers are designed and demonstrated by using either the insulating or metallic state of vanadium dioxide at the impedance matched condition. The planar multilayered absorbers exhibit tunable absorption bands over the wavelength ranges of 5-9.3 μm and 3.9-8.2 μm, respectively. A large modulation depth up to 88% is measured. The demonstrated broadband absorbance tunability is of potential interest for reconfigurable bolometric sensing, camouflaging, and modulation of mid-infrared lights.

  1. Broadband electromagnetic dipole scattering by coupled multiple nanospheres

    Science.gov (United States)

    Jing, Xufeng; Ye, Qiufeng; Hong, Zhi; Zhu, Dongshuo; Shi, Guohua

    2017-11-01

    With the development of nanotechnology, the ability to manipulate light at the nanoscale is critical to future optical functional devices. The use of high refractive index dielectric single silicon nanoparticle can achieve electromagnetic dipole resonant properties. Compared with single nanosphere, the use of dimer and trimer introduces an additional dimension (gap size) for improving the performance of dielectric optical devices through the coupling between closely connected silicon nanospheres. When changing the gap size between the nanospheres, the interaction between the particles can be from weak to strong. Compared with single nanospheres, dimerized or trimeric nanospheres exhibit more pronounced broadband scattering properties. In addition, by introducing more complex interaction, the trimericed silicon nanospheres exhibit a more significant increase in bandwidth than expected. In addition, the presence of the substrate will also contribute to the increase in the bandwidth of the nanospheres. The broadband response in dielectric nanostructures can be effectively applied to broadband applications such as dielectric nanoantennas or solar cells.

  2. 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.

  3. Upper Bound Performance Estimation for Copper Based Broadband Access

    DEFF Research Database (Denmark)

    Jensen, Michael; Gutierrez Lopez, Jose Manuel

    2012-01-01

    Around 70% of all broadband connections in the European Union are carried over copper, and the scenario is unlikely to change in the next few years as carriers still believe in the profitability of their copper infrastructure. In this paper we show how to estimate the performance upper bound of c...... to define the limitations of copper based broadband access. A case study in a municipality in Denmark shows how the estimated network dimension to be able to provide video conference services to the majority of the population might be too high to be implemented in reality.......Around 70% of all broadband connections in the European Union are carried over copper, and the scenario is unlikely to change in the next few years as carriers still believe in the profitability of their copper infrastructure. In this paper we show how to estimate the performance upper bound...

  4. Realization of Broadband Matched Filter Structures Based on Dual Networks

    Directory of Open Access Journals (Sweden)

    M. Gerding

    2005-01-01

    Full Text Available This paper deals with the basic electrical properties of dual networks and with their application in broadband matched filter structures. Starting with the main characteristics and different realization methods of dual networks, a filter structure is presented, which is based on a combination of dual networks and which provides a broadband matched input and two decoupled output ports. This filter synthesis focuses on the design of high pass filters, which are suitable to be used as differentiating stages in electrical pulse generators as a part of the so-called pulse shaping network. In order to achieve a proper pulse shape and for the prevention of multiple reflections between the switching circuit and the differentiating network, a broadband matched filter is a basic requirement.

  5. Broadband polymer microstructured THz fiber coupler with downdoped cores

    DEFF Research Database (Denmark)

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

    2010-01-01

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

  6. Crosstalk analysis of a broadband data communications system

    Energy Technology Data Exchange (ETDEWEB)

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

    1987-11-01

    A broadband cable system represents a significant resource for data transmission within a facility. Duplication of a broadband network to provide services of varying sensitivity levels within the same area is wasteful of capital resources. The sharing of a network by different data services is financially attractive providing that sensitive data are inaccessible from nonsensitive ports. The use of equipment from two manufacturers introduces a deliberate incompatibility for the purpose of data isolation. This report presents test results obtained by this technique. 4 refs., 26 figs.

  7. Design of Metamaterial Surfaces with Broad-band Absorbance

    OpenAIRE

    Wu, Chihhui; Shvets, Gennady

    2011-01-01

    A simple design paradigm for making broad-band ultra-thin plasmonic absorbers is introduced. The absorber's unit cell is composed of sub-units of various sizes, resulting in nearly 100% absorbance at multiple adjacent frequencies and high absorbance over a broad frequency range. A simple theoretical model for designing broad-band absorbers is presented. It uses a single-resonance model to describe the optical response of each sub-unit and employs the series circuit model to predict the overal...

  8. 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)

  9. Semiconductor Quantum Dash Broadband Emitters: Modeling and Experiments

    KAUST Repository

    Khan, Mohammed Zahed Mustafa

    2013-10-01

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

  10. Preliminary study on broadband antireflection coatings for large aperture telescopes

    Science.gov (United States)

    Wang, Ye-Ru; Li, Xin-Nan; Wang, Jin-Feng; Tian, Jie

    2017-12-01

    A broadband anti-reflective (AR) coating design for astronomical large-aperture telescopes is proposed. We give simulations of two-, three- and four-layer silica sol-gel on fused silica and finally get the optimal optical constants. As a comparison, we discuss the traditional dielectric material that has been applied to broadband AR coatings. To better guide the following experiment, we also conduct error analysis and feasibility analysis, combining with the technological characteristics of sol-gel. The analytical method is suitable for other wavebands and substrates. It is also instructive for large area AR coatings in the field of solar cells.

  11. Broadband high reflectivity in subwavelength-grating slab waveguides.

    Science.gov (United States)

    Tian, Hao; Cui, Xuan; Du, Yan; Tan, Peng; Shi, Guang; Zhou, Zhongxiang

    2015-10-19

    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 (Δf / ̅f > 30%). The incident-angle region with R > 0.99 extends over a range greater than 40°. Moreover, an asymmetric waveguide structure with a semiconductor substrate is studied.

  12. 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....

  13. Fast recursive algorithm for broadband APFs using complex cepstrums.

    Science.gov (United States)

    Phua, P B; Ippen, E

    2004-10-04

    Integrated-optical All-Pass Filters are of interest for their potential compactness and economy of production. For broadband applications, the number of APFs involved can be as large as 50. To find optima for all the large number of parameters involved, we need a fast and efficient algorithm based on recursive equations. APF design algorithms based on complex cepstrum are proposed in digital signal processing. In this paper, we enhance these algorithms to efficiently fit the differential phase profile required for in-line broadband Polarization Mode Dispersion and Polarization Dependent Loss compensation.

  14. 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.

  15. Achieving broadband electromagnetic transparency with transmission line metamaterials

    Science.gov (United States)

    Li, Tinghua; Huang, Ming; Yang, Jingjing; Xu, Xingui; Chen, Min

    2015-04-01

    Electromagnetic transparent device (ETD) capable of protecting the device inside without affecting its performance is a fascinating device with extensive application prospects. In this paper, an equivalent circuit method for realizing ETD using transmission line (TL) metamaterials is presented. The validity of such a method and the transparent effect of the device are demonstrated through the Agilent's Advanced Design System (ADS) circuit simulator. Moreover, the influence of the quality factor of lumped elements on the performance of the device and its broadband characteristics are also investigated. This work suggests an alternative way to achieve the broadband electromagnetic transparency and has great guiding significance for the practical fabrication of ETD.

  16. 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...

  17. 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...

  18. VT Current and Future Status of Broadband Availability by Sub-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...

  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. 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...

  1. 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...

  2. 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...

  3. Refinements to the Graves and Pitarka (2010) Broadband Ground-Motion Simulation Method

    Energy Technology Data Exchange (ETDEWEB)

    Graves, R.; Pitarka, A.

    2014-12-17

    This brief article describes refinements to the Graves and Pitarka (2010) broadband ground-motion simulation methodology (GP2010 hereafter) that have been implemented in version 14.3 of the Southern California Earthquake Center (SCEC) Broadband Platform (BBP).

  4. VT Fiber Optic 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...

  5. 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...

  6. 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...

  7. 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...

  8. 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...

  9. 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…

  10. 76 FR 13797 - Rural Broadband Access Loans and Loan Guarantees Program

    Science.gov (United States)

    2011-03-14

    ... (download plus upload speeds) for both fixed and mobile broadband service and the broadband lending speed will be a minimum bandwidth of 5 megabits per second for both fixed and mobile service to the customer...; ] DEPARTMENT OF AGRICULTURE Rural Utilities Service Rural Broadband Access Loans and Loan Guarantees Program...

  11. Interoperability of Services in an Open Broadband Market : Cases from the Netherlands

    NARCIS (Netherlands)

    Burgmeijer, J.

    2006-01-01

    End-to-end interoperability of broadband services and networks is a condition for an open broadband market. A business model for broadband service interoperability is given. Two cases from the Netherlands, of initiatives from the market to reach interoperability, are presented: E-norm and FIST VoIP.

  12. 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

  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

  14. 75 FR 38385 - Unleashing the Wireless Broadband Revolution

    Science.gov (United States)

    2010-07-01

    ... beginning the next transformation in information technology: the wireless broadband revolution. Few... applications that will transform Americans' lives. Spectrum and the new technologies it enables also are... myriad of wireless devices, networks, and applications that can drive the new economy. To do so, we can...

  15. Catalyzing Broadband Internet in Africa | CRDI - Centre de ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    This project aims to inform policies that help marginalized groups in Africa, such as women and the poor, to take advantage of the social and economic opportunities of broadband Internet. Internet access is critical for social and economic development in developing countries. According to a 2009 World Bank study, a 10% ...

  16. Broadband illusion optical devices based on conformal mappings

    Science.gov (United States)

    Xiong, Zhan; Xu, Lin; Xu, Ya-Dong; Chen, Huan-Yang

    2017-10-01

    In this paper, we propose a simple method of illusion optics based on conformal mappings. By carefully developing designs with specific conformal mappings, one can make an object look like another with a significantly different shape. In addition, the illusion optical devices can work in a broadband of frequencies.

  17. Supporting QoS in broadband wireless and wired access

    NARCIS (Netherlands)

    Peelen, Bastien; Zivkovic, Miroslav; Bijwaard, D.; Teunissen, Harold

    2003-01-01

    Wireless local area network (WLAN), cable, and digital subscriber line (xDSL) are among the most popular broadband access technologies in use today. In all such technologies, the transport capacity provided at the level of the physical medium is non-deterministically shared by different traffic

  18. Single-shot spectroscopy of broadband Yb fiber laser

    Science.gov (United States)

    Suzuki, Masayuki; Yoneya, Shin; Kuroda, Hiroto

    2017-02-01

    We have experimentally reported on a real-time single-shot spectroscopy of a broadband Yb-doped fiber (YDF) laser which based on a nonlinear polarization evolution by using a time-stretched dispersive Fourier transformation technique. We have measured an 8000 consecutive single-shot spectra of mode locking and noise-like pulse (NLP), because our developed broadband YDF oscillator can individually operate the mode locking and NLP by controlling a pump LD power and angle of waveplates. A shot-to-shot spectral fluctuation was observed in NLP. For the investigation of pulse formation dynamics, we have measured the spectral evolution in an initial fluctuations of mode locked broadband YDF laser at an intracavity dispersion of 1500 and 6200 fs2 for the first time. In both case, a build-up time between cw and steady-state mode locking was estimated to be 50 us, the dynamics of spectral evolution between cw and mode locking, however, was completely different. A shot-to-shot strong spectral fluctuation, as can be seen in NLP spectra, was observed in the initial timescale of 20 us at the intracavity dispersion of 1500 fs2. These new findings would impact on understanding the birth of the broadband spectral formation in fiber laser oscillator.

  19. 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...

  20. 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...

  1. Broadband optical beam forming for airborne phased array antenna

    NARCIS (Netherlands)

    Schippers, H.; Verpoorte, J.; Jorna, P.; Hulzinga, A.; Zhuang, L.; Meijerink, Arjan; Roeloffzen, C.G.H.; Marpaung, D.A.I.; van Etten, Wim; Heideman, Rene; Leinse, Arne; Wintels, M.

    2009-01-01

    For enhanced communication on board aircraft, novel antenna systems with broadband satellite-based capabilities are required. The technology will enhance airline operations by providing in-flight connectivity for flight crew information and will bring live TV and high-speed Internet connectivity to

  2. Rwanda's policy vacuum could mean trouble for broadband

    International Development Research Centre (IDRC) Digital Library (Canada)

    IDRC CRDI

    company Electrogaz has also decided to establish a private fibre-optic network alongside its grid. ... The main beneficiaries of broadband services are the private sector, particularly banks and insurance companies that have ... Establishing a framework that allows free and fair competition in the market is important.

  3. 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 ove...... an extremely broad (octave-spanning) frequency range....

  4. 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.

  5. 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.

  6. 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.

  7. Novel crystalline-waveguide broadband light sources for interferometry

    NARCIS (Netherlands)

    Pollnau, Markus

    In recent years, broadband fiber interferometers have become very popular as basic instruments used in optical low-coherence reflectometry for diagnostics of fiber and integrated optics devices or in optical coherence tomography (OCT) for imaging applications in the biomedical field. The

  8. Broadband nanoindentation of glassy polymers: Part II. Viscoplasticity

    Science.gov (United States)

    Joseph E. Jakes; Rod S. Lakes; Don S. Stone

    2012-01-01

    The relationship between hardness and flow stress in glassy polymers is examined. Materials studied include poly(methylmethacrylate), polystyrene, and polycarbonate. Properties are strongly rate dependent, so broadband nanoindentation creep (BNC) is used to measure hardness across a broad range of indentation strain rates (10-4 to 10 s

  9. Drivers and barriers for development of alternative broadband

    DEFF Research Database (Denmark)

    Tadayoni, Reza; Sigurdsson, Halldór Matthias

    2005-01-01

    Alternative broadband infrastructures are emerging and developing very fast. Different technologies and organization/business models have been used to establish these networks. The aim of the paper is to understand and identify the technological, economic and political/regulatory drivers and barr...

  10. PHEMT Distributed Power Amplifier Adopting Broadband Impedance Transformer

    DEFF Research Database (Denmark)

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

    2013-01-01

    A non-uniform drain line distributed power amplifier (DPA) employing a broadband impedance transformer is presented. The DPA is based on GaAs PHEMT technology. The impedance transformer employs asymmetric coupled lines and transforms a low output impedance of the amplifier to a standard 50 Ω...

  11. 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

  12. Assessment of broadband snr estimation for hearing aid applications

    DEFF Research Database (Denmark)

    May, Tobias; Kowalewski, Borys; Fereczkowski, Michal

    2017-01-01

    An accurate estimation of the broadband input signal-to-noise ratio (SNR) is a prerequisite for many hearing-aid algorithms. An extensive comparison of three SNR estimation algorithms was performed. Moreover, the influence of the duration of the analysis window on the SNR estimation performance...

  13. Modelling and control of broadband traffic using multiplicative ...

    Indian Academy of Sciences (India)

    ... of which at an interval indicates the burstiness in the traffic at that point. This value has to be estimated and used for the estimation of the congestion and predictive control of the traffic in broadband networks. The estimation can be done by employing wavelet transforms and a Kalman filter based predictor for predicting the ...

  14. 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...

  15. Concave serrations on broadband trailing edge noise reduction

    NARCIS (Netherlands)

    Ragni, D.; Avallone, F.; van der Velden, W.C.P.

    2017-01-01

    The far-field noise and flow field of a novel curved trailing-edge serration (i.e. iron-shaped) are investigated. Spectra of the far-field broadband noise, directivity plots and the flow-field over the iron-shaped serration are obtained from numerical computations performed using a compressible

  16. Developing a broadband automatic speech recognition system for Afrikaans

    CSIR Research Space (South Africa)

    De Wet, Febe

    2011-08-01

    Full Text Available Afrikaans is one of the eleven official languages of South Africa. It is classified as an under-resourced language. No annotated broadband speech corpora currently exist for Afrikaans. This article reports on the development of speech resources...

  17. Architectures for ku-band broadband airborne satellite ccommunication antennas

    NARCIS (Netherlands)

    Verpoorte, Jaco; Schippers, Harmen; Jorna, Pieter; Roeloffzen, C.G.H.; Marpaung, D.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

  18. 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…

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

    Science.gov (United States)

    Xu, Ziyong; Li, Zhi; Li, Jian

    2016-09-28

    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.

  20. 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.

  1. 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.

  2. Broadband THz waveguiding and high-precision broadband time-resolved spectroscopy

    DEFF Research Database (Denmark)

    Cooke, David; Iwaszczuk, Krzysztof; Nielsen, Kristian

    2009-01-01

    , have tailored dispersion and may be bent into sharp bends. Due to the confinement of the THz field in the core of the fibers they are ideal for stable guiding of THz light in confined environments, and may serve as a useful basis for a wealth of fiber-based photonic components in the THz range......We demonstrate optical fibers designed for the THz frequency range, fabricated in a low-loss polymer. The polymer fibers display a broadband loss of 0.4 dB/cm over the 0.1-1 THz range, with a minimum loss of 0.1 dB/cm in the region near 500 GHz. The fibers, based on endlessly single-mode design......, particularly in spectroscopic applications where tight confinement of the THz field is required. We further demonstrate a new spectroscopic technique for ultrafast time-resolved THz time-domain spectroscopy which simultaneously acquires both reference and sample data. By using this scheme we show...

  3. 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

  4. 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 f...... 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.......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...

  5. 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 ...

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

    Science.gov (United States)

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

    2016-05-01

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

  7. Broadband circularly polarizing dichroism with high efficient plasmonic helical surface.

    Science.gov (United States)

    Hu, Jingpei; Zhao, Xiaonan; Li, Ruibin; Zhu, Aijiao; Chen, Linghua; Lin, Yu; Cao, Bing; Zhu, Xiaojun; Wang, Chinhua

    2016-05-16

    We propose and experimentally demonstrate a broadband and high efficient circularly polarizing dichroism using a simple single-cycle and single-helical plasmonic surface array arranged in square lattice. Two types of helical surface structures (partially or completely covered with a gold film) are investigated. It is shown that the circular polarization dichroism in the mid-IR range (3µm - 5µm) can reach 80% (when the surface is partially covered with gold) or 65% (when the surface is completely covered with gold) with a single-cycle and single-helical surface. Experimental fabrications of the proposed helical plasmonic surface are implemented with direct 3D laser writing followed by electron beam evaporation deposition of gold. The experimental evaluations of the circular polarization dichroism are in excellent agreement with the simulation. The proposed helical surface structure is of advantages of easy-fabrication, high-dichroism and scalable to other frequencies as a high efficient broadband circular polarizer.

  8. High-frequency broadband modulation of electroencephalographic spectra

    Directory of Open Access Journals (Sweden)

    Julie A Onton

    2009-12-01

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

  9. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Ciubotaru, F., E-mail: Florin.Ciubotaru@imec.be [imec, Kapeldreef 75, B-3001 Leuven (Belgium); KU Leuven, Departement Electrotechniek (ESAT), Kasteelpark Arenberg 10, B-3001 Leuven (Belgium); Devolder, T. [Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91405 Orsay (France); Manfrini, M.; Adelmann, C.; Radu, I. P. [imec, Kapeldreef 75, B-3001 Leuven (Belgium)

    2016-07-04

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

  11. 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...... that of the gold, Various other design options are discussed, and we conclude that continued interest in the X-ray supermirror for broad-band hard X-ray applications is warranted....... of the multilayer is found to agree extraordinarily well with theory (assuming an interface roughness of 4.5 Angstrom), while the agreement for the gold film is less, The overall performance of the supermirror is superior to that of gold, extending the band of reflection at least a factor of 2.8 beyond...

  12. Monolithic optoelectronic integrated broadband optical receiver with graphene photodetectors

    Directory of Open Access Journals (Sweden)

    Cheng Chuantong

    2017-07-01

    Full Text Available Optical receivers with potentially high operation bandwidth and low cost have received considerable interest due to rapidly growing data traffic and potential Tb/s optical interconnect requirements. Experimental realization of 65 GHz optical signal detection and 262 GHz intrinsic operation speed reveals the significance role of graphene photodetectors (PDs in optical interconnect domains. In this work, a novel complementary metal oxide semiconductor post-backend process has been developed for integrating graphene PDs onto silicon integrated circuit chips. A prototype monolithic optoelectronic integrated optical receiver has been successfully demonstrated for the first time. Moreover, this is a firstly reported broadband optical receiver benefiting from natural broadband light absorption features of graphene material. This work is a perfect exhibition of the concept of monolithic optoelectronic integration and will pave way to monolithically integrated graphene optoelectronic devices with silicon ICs for three-dimensional optoelectronic integrated circuit chips.

  13. Monolithic optoelectronic integrated broadband optical receiver with graphene photodetectors

    Science.gov (United States)

    Cheng, Chuantong; Huang, Beiju; Mao, Xurui; Zhang, Zanyun; Zhang, Zan; Geng, Zhaoxin; Xue, Ping; Chen, Hongda

    2017-07-01

    Optical receivers with potentially high operation bandwidth and low cost have received considerable interest due to rapidly growing data traffic and potential Tb/s optical interconnect requirements. Experimental realization of 65 GHz optical signal detection and 262 GHz intrinsic operation speed reveals the significance role of graphene photodetectors (PDs) in optical interconnect domains. In this work, a novel complementary metal oxide semiconductor post-backend process has been developed for integrating graphene PDs onto silicon integrated circuit chips. A prototype monolithic optoelectronic integrated optical receiver has been successfully demonstrated for the first time. Moreover, this is a firstly reported broadband optical receiver benefiting from natural broadband light absorption features of graphene material. This work is a perfect exhibition of the concept of monolithic optoelectronic integration and will pave way to monolithically integrated graphene optoelectronic devices with silicon ICs for three-dimensional optoelectronic integrated circuit chips.

  14. Broadband and chiral binary dielectric meta-holograms.

    Science.gov (United States)

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

    2016-05-01

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

  15. 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

  16. 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

    2016-08-30

    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.

  17. Transparent broadband metamaterial absorber based on resistive films

    Science.gov (United States)

    Sheokand, Harsh; Ghosh, Saptarshi; Singh, Gaganpreet; Saikia, Mondeep; Srivastava, Kumar Vaibhav; Ramkumar, J.; Anantha Ramakrishna, S.

    2017-09-01

    In this paper, an optically transparent metamaterial with broadband absorption is presented theoretically and demonstrated experimentally. The design comprises of structures made of resistive films of indium-tin-oxide and the metamaterial exhibits over 10 dB absorption in the frequency range of 6.06-14.66 GHz. The novelty of the structure lies in its large absorption bandwidth along with a reduced thickness and optical transparency compared to broadband absorbers reported earlier. Besides, the proposed design is polarization-insensitive and gives rise to angular independent absorption for both transverse electric and transverse magnetic polarizations. The absorption mechanism in the structure has been studied by deriving an equivalent circuit model as well as analyzing several design parameters. Finally, a prototype of the proposed structure has been fabricated and measured, which shows good agreement with the simulated results.

  18. 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.

  19. 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.

  20. 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.

  1. Dictionary for Sparse Representation of Chirp Echo in Broadband Radar

    OpenAIRE

    Gao, Lei

    2010-01-01

    A new dictionary for sparse representation of chirp echo in broadband radar is put forward in this paper. Different with chirplet decomposition which decomposes echo in time-frequency plane, the dictionary transforms the sparsity of target observed by radar in distance range to the sparsity in frequency domain by stretch processing and the sparse representation of echo is realized. Using strict deduction with mathematics, the sparsity of echo in dictionary is proved and the dictionary is orth...

  2. Broadband light-induced absorbance change in multilayer graphene.

    Science.gov (United States)

    Obraztsov, Petr A; Rybin, Maxim G; Tyurnina, Anastasia V; Garnov, Sergey V; Obraztsova, Elena D; Obraztsov, Alexander N; Svirko, Yuri P

    2011-04-13

    We report the ultrafast light-induced absorbance change in CVD-grown multilayer graphene. Using femtosecond pump-probe measurements in 1100-1800 nm spectral range, we revealed broadband absorbance change when the probe photon energy was higher than that of the pump photon. The observed phenomenon is interpreted in terms of the Auger recombination and impact ionization playing a significant role in the dynamics of photoexcited carriers in graphene.

  3. Broadband infrared meanderline reflective quarter-wave plate.

    Science.gov (United States)

    Wadsworth, Samuel L; Boreman, Glenn D

    2011-05-23

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

  4. Gain-assisted broadband ring cavity enhanced spectroscopy

    Science.gov (United States)

    Selim, Mahmoud A.; Adib, George A.; Sabry, Yasser M.; Khalil, Diaa

    2017-02-01

    Incoherent broadband cavity enhanced spectroscopy can significantly increase the effective path length of light-matter interaction to detect weak absorption lines over broad spectral range, for instance to detect gases in confined environments. Broadband cavity enhancement can be based on the decay time or the intensity drop technique. Decay time measurement is based on using tunable laser source that is expensive and suffers from long scan time. Intensity dependent measurement is usually reported based on broadband source using Fabry-Perot cavity, enabling short measurement time but suffers from the alignment tolerance of the cavity and the cavity insertion loss. In this work we overcome these challenges by using an alignment-free ring cavity made of an optical fiber loop and a directional coupler, while having a gain medium pumped below the lasing threshold to improve the finesse and reduce the insertion loss. Acetylene (C2H2) gas absorption is measured around 1535 nm wavelength using a semiconductor optical amplifier (SOA) gain medium. The system is analyzed for different ring resonator forward coupling coefficient and loses, including the 3-cm long gas cell insertion loss and fiber connector losses used in the experimental verification. The experimental results are obtained for a coupler ratio of 90/10 and a fiber length of 4 m. The broadband source is the amplified spontaneous emission of another SOA and the output is measured using a 70pm-resolution optical spectrum analyzer. The absorption depth and the effective interaction length are improved about an order of magnitude compared to the direct absorption of the gas cell. The presented technique provides an engineering method to improve the finesse and, consequently the effective length, while relaxing the technological constraints on the high reflectivity mirrors and free-space cavity alignment.

  5. Broadband Sources in the 1-3 THz Range

    Science.gov (United States)

    Mehdi, Imran; Ward, John; Maestrini, Alain; Chattopadhyay, Goutam; Schlecht, Erich; Thomas, Bertrand; Lin, Robert; Lee, Choonsup; Gill, John

    2009-01-01

    Broadband electronically tunable sources in the terahertz range are a critical technology for enabling space-borne as well as ground-based applications. By power-combining MMIC amplifier and frequency tripler chips, we have recently demonstrated >1 mW of output power at 900 GHz. This source provides a stepping stone to enable sources in the 2-3 THz range than can sufficiently pump multi-pixel imaging arrays.

  6. On sine dwell or broadband methods for modal testing

    Science.gov (United States)

    Chen, Jay-Chung; Wada, Ben K.

    1987-01-01

    For large, complex spacecraft structural systems, the objectives of the modal test are outlined. Based on these objectives, the comparison criteria for the modal test methods, namely, the broadband excitation and the sine dwell methods are established. Using the Galileo spacecraft modal test and the Centaur G Prime upper stage vehicle modal test as examples, the relative advantages or disadvantages of each method are examined. The usefulness or shortcoming of the methods are given from a practicing engineer's view point.

  7. Comparison of sine dwell and broadband methods for modal testing

    Science.gov (United States)

    Chen, Jay-Chung

    1989-01-01

    The objectives of modal tests for large complex spacecraft structural systems are outlined. The comparison criteria for the modal test methods, namely, the broadband excitation and the sine dwell methods, are established. Using the Galileo spacecraft modal test and the Centaur G Prime upper stage vehicle modal test as examples, the relative advantage or disadvantage of each method is examined. The usefulness or shortcomings of the methods are given from a practical engineering viewpoint.

  8. Nonlinear broadband photoluminescence of graphene induced by femtosecond laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Wei-Tao; Wu, S.W.; Schuck, P.J.; Salmeron, Miquel; Shen, Y.R.; Wang, F.

    2010-07-01

    Upon femtosecond laser irradiation, a bright, broadband photoluminescence is observed from graphene at frequencies well above the excitation frequency. Analyses show that it arises from radiative recombination of a broad distribution of nonequilibrium electrons and holes, generated by rapid scattering between photoexcited carriers within tens of femtoseconds after the optical excitation. Its highly unusual characteristics come from the unique electronic and structural properties of graphene.

  9. Internet access and investment incentives for broadband service providers

    OpenAIRE

    Baranes, Edmond; Poudou, Jean-Christophe

    2011-01-01

    This paper studies a model of the Internet broadband market as a platform in order to show how di¤erent pricing schemes from the so-called "net neutrality " can increase economic e¢ ciency by allowing more investment of access providers and enhancing consumers surplus and social welfare. We show that departing from the "net neutrality", where at rates are used, introducing termination fees can increase incentives to invest for the ISP and enhance social surplus. Keywords : Network neutrality,...

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

    Science.gov (United States)

    2010-01-29

    services (an aspect of net neutrality ).97 The 2010 fiscal year budget prepared by the Office of Management and Budget projects new revenue from...detailed description of the concept and policy issues is available in CRS Report R40616, Access to Broadband Networks: The Net Neutrality Debate, by Angele...Committee, February 27, 2009, page 12. Background on the proposal is provided in this report under the section “Issues for Congress.” 97 The term net

  11. Imitating Broadband Diurnal Light Variations Using Solid State Light Sources

    Science.gov (United States)

    Ferguson, Ian; Melton, Andrew; Li, Nola; Nicol, David; Park, Eun Hyun; Tosini, Gianluca

    Many studies have documented the success of light therapy in treating disorders of the human internal clock (circadian rhythm). Recent biological research has shown the importance of developing light sources that are tunable in the blue region of the spectrum for treatment to be safe and effective. A novel tunable broadband solid-state light source is presented here that mimics the diurnal variation in sunlight by modulating the intensity of blue light emission.

  12. Broadband reflectionless metamaterials with customizable absorption-transmission-integrated performance

    Science.gov (United States)

    Shen, Yang; Zhang, Jieqiu; Pang, Yongqiang; Li, Yongfeng; Zheng, QiQi; Wang, Jiafu; Ma, Hua; Qu, Shaobo

    2017-08-01

    Broadband reflectionless metamaterials with customizable absorption-transmission-integrated performance are proposed, discussed, and demonstrated in this paper. The three-dimensional metamaterial absorbers (MAs) consist of multilayered metal-insulator composition which are introduced here for broadband electromagnetic wave absorption. The frequency selective surfaces (FSSs) backed on the bottom also help achieve multi-transmissions inside or outside of the absorption band. Simulations indicate that diversiform combinations of the MAs and the FSSs will contribute more choice of customizable absorption-transmission-integrated performance. Compared with the foregoing designs, the three-dimensional MAs used here possess broadband absorption with abrupt transition zone which are easier to achieve absorption-transmission-integrated performance with almost no reflection during the entire frequency band. Meanwhile, the simple component and the easy fabrication also make it possible for the absorption-transmission-integrated metamaterials (ATMAs) to be referenced at higher frequencies, such as infrared or optical frequencies. At last, an experimental proof is given at the microwave frequencies. The good agreement between simulation and measurement indicates that our proposed ATMAs will exhibit great potential applications, for example, stealth technology, communication security, and selective multi-frequency sensing.

  13. Broadband source localization using horizontal-beam acoustic intensity striations.

    Science.gov (United States)

    Turgut, Altan; Orr, Marshall; Rouseff, Daniel

    2010-01-01

    Waveguide invariant theory is applied to horizontal line array (HLA) beamformer output to localize moving broadband noise sources from measured acoustic intensity striation patterns. Acoustic signals emitted by ships of opportunity (merchant ships) were simultaneously recorded on a HLA and three hydrophones separated by 10 km during the RAGS03 (relationship between array gain and shelf-break fluid processes) experiment. Hough transforms are used to estimate both the waveguide invariant parameter "beta" and the ratio of source range at the closest point of approach to source speed from the observed striation patterns. Broadband (50-150-Hz) acoustic data-sets are used to demonstrate source localization capability as well as inversion capability of waveguide invariant parameter beta. Special attention is paid to bathymetric variability since the acoustic intensity striation patterns seem to be influenced by range-dependent bathymetry of the experimental area. The Hough transform method is also applied to the HLA beam-time record data and to the acoustic intensity data from three distant receivers to validate the estimation results from HLA beamformer output. Good agreement of the results from all three approaches suggests the feasibility of locating broadband noise sources and estimating waveguide invariant parameter beta in shallow waters.

  14. Tracing the phase of focused broadband laser pulses

    Science.gov (United States)

    Hoff, Dominik; Krüger, Michael; Maisenbacher, Lothar; Sayler, A. M.; Paulus, Gerhard G.; Hommelhoff, Peter

    2017-10-01

    Precise knowledge of the behaviour of the phase of light in a focused beam is fundamental to understanding and controlling laser-driven processes. More than a hundred years ago, an axial phase anomaly for focused monochromatic light beams was discovered and is now commonly known as the Gouy phase. Recent theoretical work has brought into question the validity of applying this monochromatic phase formulation to the broadband pulses becoming ubiquitous today. Based on electron backscattering at sharp nanometre-scale metal tips, a method is available to measure light fields with sub-wavelength spatial resolution and sub-optical-cycle time resolution. Here we report such a direct, three-dimensional measurement of the spatial dependence of the optical phase of a focused, 4-fs, near-infrared pulsed laser beam. The observed optical phase deviates substantially from the monochromatic Gouy phase--exhibiting a much more complex spatial dependence, both along the propagation axis and in the radial direction. In our measurements, these significant deviations are the rule and not the exception for focused, broadband laser pulses. Therefore, we expect wide ramifications for all broadband laser-matter interactions, such as in high-harmonic and attosecond pulse generation, femtochemistry, ophthalmological optical coherence tomography and light-wave electronics.

  15. 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.

  16. A Broadband Bessel Beam Launcher Using Metamaterial Lens.

    Science.gov (United States)

    Qi, Mei Qing; Tang, Wen Xuan; Cui, Tie Jun

    2015-06-30

    An approach of generating broadband Bessel beams is presented. The broadband Bessel beams are produced by a gradient index (GRIN) metamaterial lens illuminated by broadband waveguide antenna. The metamaterial lens is constructed with multi-layered structure and each layer is composed of GRIN metamaterials. The metamaterials are designed as dielectric plates printed with metallic patterns in the center region and drilled by air holes near the edge, which operate in wide band. The metamaterial lens serves as a convertor which transforms the spherical beams emitted from feed into conical beams. The conical beams form quasi-Bessel beams in the near-field region. The aperture diameter of the GRIN lens is much larger than the operating wavelength to guarantee the transformation. In principle, this kind of metamaterial lens can produce Bessel beams at arbitrary distance by designing the refractive-index distribution. To verify the approach, we have designed, fabricated and tested a metamaterial lens. Full-wave simulation and experiment results have proved that the generated Bessel beams can be maintained in distance larger than 1 meter within a ranging from 12 GHz to 18 GHz.

  17. Detection and characterization of pulses in broadband seismometers

    Science.gov (United States)

    Wilson, David; Ringler, Adam; Hutt, Charles R.

    2017-01-01

    Pulsing - caused either by mechanical or electrical glitches, or by microtilt local to a seismometer - can significantly compromise the long‐period noise performance of broadband seismometers. High‐fidelity long‐period recordings are needed for accurate calculation of quantities such as moment tensors, fault‐slip models, and normal‐mode measurements. Such pulses have long been recognized in accelerometers, and methods have been developed to correct these acceleration steps, but considerable work remains to be done in order to detect and correct similar pulses in broadband seismic data. We present a method for detecting and characterizing the pulses using data from a range of broadband sensor types installed in the Global Seismographic Network. The technique relies on accurate instrument response removal and employs a moving‐window approach looking for acceleration baseline shifts. We find that pulses are present at varying levels in all sensor types studied. Pulse‐detection results compared with average daily station noise values are consistent with predicted noise levels of acceleration steps. This indicates that we can calculate maximum pulse amplitude allowed per time window that would be acceptable without compromising long‐period data analysis.

  18. 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.

  19. Broadband polarization-insensitive absorber based on gradient structure metamaterial

    Science.gov (United States)

    Yang, Guo-Hui; Liu, Xiao-Xin; Lv, Yue-Long; Fu, Jia-Hui; Wu, Qun; Gu, Xuemai

    2014-05-01

    Metamaterial absorber (MA) is a hot spot in the research on electromagnetic absorbers. In this paper, a metamaterial based broadband polarization-insensitive absorber is proposed. The absorber is fabricated with FR-4 dielectric substrate foiled with copper. The top layer of the unit cell of the MA is composed of resistors mounted crosswire and gradient split ring resonator (SRR) with a square metal patch (SMP) in it. The overall structure is symmetrical, which makes the MA polarization-insensitive. The gradient SRRs and SMPs resonate at adjacent frequencies resulting in broadband property. The absorption rates of the MA for TE and TM wave are calculated through the simulated S-parameters. The bandwidth is 9.9 GHz, where the absorption rate maintains 60% up to 98.28% in both cases and the relative bandwidth is 57.13%. Both broadband and polarization-insensitivity properties are achieved, which demonstrate promising application prospect of the proposed MA in shielding and stealth technology.

  20. Crustal thickness investigation on three broadband stations in Northern Sumatra

    Science.gov (United States)

    Anggono, T.; Syuhada; Soedjatmiko, B.; Amran, A.

    2017-04-01

    We present a preliminary result of crustal thickness in Northern Sumatra from receiver function analysis and grid search. Total of 111 teleseismic events from three broadband stations (TPTI, KCSI, and BSI) of IA-Network were used to calculate the receiver functions. We identified direct P and S arrival from the receiver function. Converted phases Ps were relatively clear for all three broadband stations. Ps-P time was estimated about 2 - 3 s, 2 s, and 5 - 6 s for station TPTI, KCSI, and BSI, respectively. We applied H-k stacking method to obtain crustal thickness and Vp/Vs ratio beneath the three broadband stations. At station TPTI, we obtained the crustal thickness is about 19.54 ± 3.84 km, Vp/Vs ratio is about 1.73 ± 0.14. At station KCSI, the crustal thickness was estimated to be 37.07 ± 4.47 km, Vp/Vs ratio is about 1.84 ± 0.10. At station BSI, which is located to the north of these two stations, the crustal thickness was estimated to be 40.56 ± 2.26 km, Vp/Vs ratio is about 1.81 ± 0.05. These results show relatively large variation of crustal thickness in the Northern Sumatra.

  1. Discrete and broadband electron acceleration in Jupiter's powerful aurora.

    Science.gov (United States)

    Mauk, B H; Haggerty, D K; Paranicas, C; Clark, G; Kollmann, P; Rymer, A M; Bolton, S J; Levin, S M; Adriani, A; Allegrini, F; Bagenal, F; Bonfond, B; Connerney, J E P; Gladstone, G R; Kurth, W S; McComas, D J; Valek, P

    2017-09-06

    The most intense auroral emissions from Earth's polar regions, called discrete for their sharply defined spatial configurations, are generated by a process involving coherent acceleration of electrons by slowly evolving, powerful electric fields directed along the magnetic field lines that connect Earth's space environment to its polar regions. In contrast, Earth's less intense auroras are generally caused by wave scattering of magnetically trapped populations of hot electrons (in the case of diffuse aurora) or by the turbulent or stochastic downward acceleration of electrons along magnetic field lines by waves during transitory periods (in the case of broadband or Alfvénic aurora). Jupiter's relatively steady main aurora has a power density that is so much larger than Earth's that it has been taken for granted that it must be generated primarily by the discrete auroral process. However, preliminary in situ measurements of Jupiter's auroral regions yielded no evidence of such a process. Here we report observations of distinct, high-energy, downward, discrete electron acceleration in Jupiter's auroral polar regions. We also infer upward magnetic-field-aligned electric potentials of up to 400 kiloelectronvolts, an order of magnitude larger than the largest potentials observed at Earth. Despite the magnitude of these upward electric potentials and the expectations from observations at Earth, the downward energy flux from discrete acceleration is less at Jupiter than that caused by broadband or stochastic processes, with broadband and stochastic characteristics that are substantially different from those at Earth.

  2. Discrete and broadband electron acceleration in Jupiter's powerful aurora

    Science.gov (United States)

    Mauk, B. H.; Haggerty, D. K.; Paranicas, C.; Clark, G.; Kollmann, P.; Rymer, A. M.; Bolton, S. J.; Levin, S. M.; Adriani, A.; Allegrini, F.; Bagenal, F.; Bonfond, B.; Connerney, J. E. P.; Gladstone, G. R.; Kurth, W. S.; McComas, D. J.; Valek, P.

    2017-09-01

    The most intense auroral emissions from Earth's polar regions, called discrete for their sharply defined spatial configurations, are generated by a process involving coherent acceleration of electrons by slowly evolving, powerful electric fields directed along the magnetic field lines that connect Earth's space environment to its polar regions. In contrast, Earth's less intense auroras are generally caused by wave scattering of magnetically trapped populations of hot electrons (in the case of diffuse aurora) or by the turbulent or stochastic downward acceleration of electrons along magnetic field lines by waves during transitory periods (in the case of broadband or Alfvénic aurora). Jupiter's relatively steady main aurora has a power density that is so much larger than Earth's that it has been taken for granted that it must be generated primarily by the discrete auroral process. However, preliminary in situ measurements of Jupiter's auroral regions yielded no evidence of such a process. Here we report observations of distinct, high-energy, downward, discrete electron acceleration in Jupiter's auroral polar regions. We also infer upward magnetic-field-aligned electric potentials of up to 400 kiloelectronvolts, an order of magnitude larger than the largest potentials observed at Earth. Despite the magnitude of these upward electric potentials and the expectations from observations at Earth, the downward energy flux from discrete acceleration is less at Jupiter than that caused by broadband or stochastic processes, with broadband and stochastic characteristics that are substantially different from those at Earth.

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

    National Research Council Canada - National Science Library

    Kuhn, D

    2002-01-01

    This document is intended to assist those responsible - users, system administrators, and management - for telecommuting security, by providing introductory information about broadband communication...

  4. A simple design of ultra-broadband and polarization insensitive terahertz metamaterial absorber

    Science.gov (United States)

    Wang, Ben-Xin; Wang, Ling-Ling; Wang, Gui-Zhen; Huang, Wei-Qing; Li, Xiao-Fei; Zhai, Xiang

    2014-06-01

    Ultra-broadband metamaterial absorbers have attracted considerable attention due to their great prospect for practical applications. These absorbers are usually stacked by many (no. stealth technology.

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

    Science.gov (United States)

    Walton, D.J.; Furst, F.; Harrison, F.A.; Middleton, M.J.; Fabian, A. C.; Bachetti, M.; Barret, D.; Miller, J. M.; Ptak, A.; Rana, V.; hide

    2017-01-01

    We present results from four new broadband X-ray observations of the extreme ultraluminous X-ray source Holmberg IX X-1 (L (sub X) greater than 10 (sup 40) ergs per second), performed by Suzaku and NuSTAR in coordination. Combined with the archival data, 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. The spectra are well fit by two thermal blackbody components that dominate the emission below 10 kiloelectronvolts, as well as a steep (Gamma approximately equal to 3.5) power-law tail that?dominates above approximately 15 kiloelectronvolts. Remarkably, while the 0.3-10.0 kiloelectronvolts flux varies by a factor of approximately 3 between all these epochs, the 15-40 kiloelectronvolts flux varies by only approximately 20 percent. Although the spectral variability is strongest in the approximately 1-10 kiloelectronvolts band, both of the thermal components are required to vary when all epochs are considered. We also revisit the search for iron absorption features by leveraging the high-energy NuSTAR data to improve our sensitivity to extreme velocity outflows in light of the ultra-fast outflow recently detected in NGC 1313 X-1. Iron absorption from a similar outflow along our line of sight can be ruled out in this case. We discuss these results in the context of super-Eddington accretion models that invoke a funnel-like geometry for the inner flow, and propose a scenario in which we have an almost face-on view of a funnel that expands to larger radii with increasing flux, resulting in an increasing degree of geometrical collimation for the emission from intermediate-temperature regions.

  6. 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.

  7. 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.

  8. 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

    2017-01-20

    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.

  9. Application of Planar Broadband Slow-Wave Systems

    Directory of Open Access Journals (Sweden)

    Edvardas Metlevskis

    2012-04-01

    Full Text Available Different types of planar broadband slow-wave systems are used for designing microwave devices. The papers published by Lithuanian scientists analyze and investigate the models of helical and meander slow-wave systems. The article carefully examines the applications of meander slow-wave systems and presents the areas where similar systems, e.g. mobile devices, RFID, wireless technologies are used and reviewed nowadays. The paper also focuses on the examples of the papers discussing antennas, filters and couplers that contain designed and fabricated meander slow-wave systems.Article in Lithuanian

  10. Broadband near-infrared metamaterial absorbers utilizing highly lossy metals

    DEFF Research Database (Denmark)

    Ding, Fei; Dai, Jin; Chen, Yiting

    2016-01-01

    demonstrate thin, broadband, polarization-insensitive and omnidirectional absorbers working in the near-infrared range. We choose titanium (Ti) instead of the commonly used gold (Au) to construct nano-disk arrays on the top of a silicon dioxide (SiO2) coated Au substrate, with the quality (Q) factor......Radiation absorbers have increasingly been attracting attention as crucial components for controllable thermal emission, energy harvesting, modulators, etc. However, it is still challenging to realize thin absorbers which can operate over a wide spectrum range. Here, we propose and experimentally...... materials....

  11. 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.

  12. 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.

  13. Coherent Lensless imaging with Ultra-Broadband Light Sources

    Directory of Open Access Journals (Sweden)

    Eikema K. S. E.

    2013-03-01

    Full Text Available We demonstrate a method for efficient lensless imaging using ultra-broadband light sources. By using a pair of time-delayed, coherent pulses in a Fourier-transform scheme, spectrally resolved diffraction patterns are obtained throughout the entire spectrum of the incident light source. We perform a proof-of-principle experiment using an octave-spanning visible light source, and obtain images of a holographic test sample with near-diffraction limited resolution. Our approach provides a promising route towards efficient high-resolution imaging using table-top high-harmonic soft-X-ray sources.

  14. 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.

  15. Broadband aberration-free focusing reflector for acoustic waves

    Science.gov (United States)

    Wang, Aixia; Qu, Shaobo; Ma, Hua; Wang, Jiafu; Jiang, Wei; Feng, Mingde

    2017-11-01

    An aberration-free focusing reflector (AFR) for acoustic waves is proposed with the aim to eliminate spherical aberration and coma simultaneously. Meanwhile, the AFR can focus acoustic waves with low dispersion in a wide frequency range of 14-50 kHz. The broadband aberration-free focusing effect is originated from an elliptical reflection phase gradient profile, which is achieved by milling different depths of axisymmetric grooves on a planoconcave-like brass plate using the ray theory. Theoretical and numerical results are in good agreement. The designed AFR can find broad engineering, industrial and medical applications.

  16. Chromatic signatures of broadband optical spectra for liquor discrimination

    Science.gov (United States)

    Jones, G. R.; Deakin, A. G.; Spencer, J. W.

    2009-02-01

    Methods based upon chromatic analysis are described for quantifying broadband optical absorption spectra in discriminating between different types of liquors. The absorption spectra are quantified by three chromaticity coordinates, which can be represented by two points, one on each of two chromatic diagrams. Various types of liquors may then be distinguished on such chromatic maps and groups of similar samples conveniently identified. Examples of the deployment of the approach are given for distinguishing between and classifying various types, brands and mixtures of alcoholic beverages and for identifying an authentic brand. The method provides a high level of traceability and is not restricted to a particular type of optical spectrum.

  17. Broadband metamaterial absorber based on coupling resistive frequency selective surface.

    Science.gov (United States)

    Sun, LiangKui; Cheng, HaiFeng; Zhou, YongJiang; Wang, Jun

    2012-02-13

    We report the design, fabrication, and measurement of a broadband metamaterial absorber, which consists of lossy frequency selective surface (FSS) and a metallic ground plane separated by a dielectric layer. The compact single unit cell of the FSS contains crisscross and fractal square patch which couple with each other. Both qualitative analysis by equivalent circuit and accurate numeric calculation show that the coupling between the crisscross and the fractal square patch can enhance the bandwidth with the reflectivity below -10dB in the frequency range of 2-18GHz by producing a third absorption null. In the end, the designed absorber was realized by experiment.

  18. Self-Affine Graphene Metasurfaces for Tunable Broadband Absorption

    Science.gov (United States)

    Wu, Pin Chieh; Papasimakis, Nikitas; Tsai, Din Ping

    2016-10-01

    Graphene has emerged as a promising platform for THz metasurfaces supporting electrically tunable deep-subwavelength plasmonic excitations. Here, we introduce a broadband graphene metasurface based on the Hilbert curve, a continuous, space-filling fractal. We demonstrate the enhancement of graphene absorption over a broad frequency band (0.5-60 THz) with an average absorption level exceeding 20%. Owing to the continuous nature of the metasurface patterns, both the absorption level and the bandwidth can be controlled electrically by varying the graphene charge-carrier concentration.

  19. Triplet-singlet conversion by broadband optical pumping

    OpenAIRE

    Horchani, Ridha; Lignier, Hans; Bouloufa-Maafa, Nadia; Fioretti, Andrea; Pillet, Pierre; Comparat, Daniel

    2012-01-01

    We demonstrate the conversion of cold Cs_{2} molecules initially distributed over several vibrational levels of the lowest triplet state a^{3}\\Sigma_{u}^{+} into the singlet ground state X^{1}\\Sigma_{g}^{+}. This conversion is realized by a broadband laser exciting the molecules to a well-chosen state from which they may decay to the singlet state throug\\textcolor{black}{h two sequential single-photon emission steps: Th}e first photon populates levels with mixed triplet-singlet character, mak...

  20. 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.

  1. 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.

  2. 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.

  3. Broadband ultrathin low-profile metamaterial microwave absorber

    Science.gov (United States)

    Sood, Deepak; Tripathi, Chandra Charu

    2016-04-01

    In this paper, a single-layer broadband low-profile ultrathin metamaterial microwave absorber is proposed for wide angle of incidence. The proposed absorber provides triple-band absorption under normal incidence of electromagnetic wave with two peaks lying in X-band and one in Ku-band. The unit cell is designed by using parametric optimization in such a way that the three peaks merge together to give broadband absorption. The absorber exhibits full width at half maxima bandwidth (FWHM) of 7.75 GHz from 7.55 to 15.30 GHz for wide angle of incidence up to 60° for both TE and TM polarizations. The mechanism of absorption of the absorber has been analyzed by field and surface current distributions. The proposed absorber has been fabricated and experimentally tested for different angles of incidence and polarization of the incident wave. The absorber is low profile with unit cell dimension of the order of 0.168 λ 0, and it is ultrathin with a thickness of ~ λ 0/17 at the center frequency of 11.43 GHz corresponding to the FWHM absorption bandwidth. This proposed absorber can be used for many potential applications such as stealth technology, cloaking and in antenna systems.

  4. 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.

  5. 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.

  6. Simple reaction time for broadband sounds compared to pure tones.

    Science.gov (United States)

    Schlittenlacher, Josef; Ellermeier, Wolfgang; Avci, Gül

    2017-02-01

    Although many studies have explored the relation between reaction time (RT) and loudness, including effects of intensity, frequency, and binaural summation, comparable work on spectral summation is rare. However, most real-world sounds are not pure tones and typically have bandwidths covering several critical bands. Since comparing to a 1-kHz pure tone, the reference tone, is important for loudness measurement and standardization, the present work focuses on comparing RTs for broadband noise to those for 1-kHz pure tones in three experiments using different spectral and binaural configurations. The results of Experiments 1 and 2 yield good quantitative agreement with spectral loudness summation models for moderate and high sound pressure levels, measured using both pink noise covering almost the entire hearing range and bandpass-filtered pink noise with different center frequencies. However, at lower levels, the RT measurements yield an interaction of level and bandwidth, which is not in line with loudness scaling data. In Experiment 3, which investigated the binaural summation of broadband sounds, the binaural gain for white noise was determined to be 9 dB, which is somewhat larger than what had been found in previous RT measurements using 1-kHz pure tones.

  7. Broadband non-unity magnetic permeability in planar hyperbolic metamaterials

    Science.gov (United States)

    Papadakis, Georgia Theano; Fleischman, Dagny; Davoyan, Artur R.; Thyagarajan, Krishnan; Atwater, Harry A.

    Metal/dielectric heterostructures with extreme anisotropy and topologically nontrivial dispersion are of fundamental and applied interest due to unique optical and opto-electronic properties. Here we demonstrate that, surprisingly, such systems exhibit a broadband non-unity magnetic response. Typically the electromagnetic properties of such metal-dielectric stacks are deduced from effective medium theories for unbounded, i.e., infinite in size periodic arrangements (c.f., Maxwell-Garnett approximation). In this talk, we show that this description is incomplete for metamaterials with finite number of layers. We demonstrate that a few-layer metal-dielectric metamaterial exhibits a non-unity magnetic permeability across the whole visible spectrum. The response can be diamagnetic or paramagnetic depending on the type of the terminating layers: metallic or dielectric, with non-resonant magnetic permeability that can be engineered to attain values as low as -2 or as high as 2. We have developed a theoretical model that explains the underlying mechanism. We further experimentally validate non-unity effective permeability in the optical range of frequencies. Ag/SiO2 and Ge-based metamaterials fabricated with electron beam evaporation are characterized by ellipsometric measurements and also phase and amplitude of transmittance/reflectance. These results open pathways for creating broadband subwavelength magnetic structures in the visible regime.

  8. HERA Broadband Feed Design for Low-Frequency Radio Astronomy

    Science.gov (United States)

    Garza, Sierra; Trung, Vincent; Ewall-Wice, Aaron Michael; Li, Jianshu; Hewitt, Jacqueline; Riley, Daniel; Bradley, Richard F.; Makhija, Krishna

    2018-01-01

    As part of the Hydrogen Epoch of Reionization Array (HERA) project, we are designing a broadband low-frequency radio feed to extend the bandwidth from 100-200 MHz to 50-220 MHz. By extending the lower-limit to 50 MHz, we hope to detect the signatures of the first black holes heating the hydrogen gas in the intergalactic medium.The isolation of a very faint signal from vastly brighter foregrounds sets strict requirements on antenna spectral smoothness, polarization purity, forward gain, and internal reflections. We are currently working to meet these requirements with a broad-band sinuous antenna feed suspended over the 14-m parabolic HERA dish, using a combination of measurements and simulations to verify the performance of our design.A sinuous feed has been designed and simulated with Computer Simulation Technology (CST) software. We will present the construction of a prototype sinuous antenna and measurements of its reflection coefficient, S11, including laboratory characterization of baluns. Our measurements agree well with the CST simulations of the antenna’s performance, giving us confidence in our ability to model the feed and ensure that it meets the requirements of a 21cm cosmology measurement.

  9. Dendritic-metasurface-based flexible broadband microwave absorbers

    Science.gov (United States)

    Wang, Mei; Weng, Bin; Zhao, Jing; Zhao, Xiaopeng

    2017-06-01

    Based on the dendritic metasurface model, a type of flexible and lightweight microwave absorber (MA) comprising resistance film array with dendritic slot (RFADS), dielectric material, and metal plate is proposed. A broadband absorptivity of >80% is obtained both from simulation and experiment at frequency ranges of 3.0-9.2 and 3.2-9.00 GHz, respectively. And the thickness of MA is 5 mm, which is only 0.05λ _{low}, or 0.15λ _ {high}, where the λ _{low} and the λ _{high} are the beginning and the end of the working frequency. By combining this metasurface-based MA with the dendritic-resistance-film-based microwave metasurface absorber (MMA), we designed a broadband MMA. The simulations and experiments showed that this kind of MMA can absorb the radiation effectively at a wide frequency range 4.5-17.5 GHz. And the thickness of this combined MMA is 4 mm. All the structures showed their insensitivity to the incident angle (0°-40°) and the polarization of the incident wave because of their structural symmetry. In addition, the small thickness, low apparent density, and flexibility made those structures possess the advantages of being applied in microwave stealth and radar cross-section (RCS) reduction.

  10. 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.

  11. Broadband ultrasound attenuation imaging: a new imaging method in osteoporosis.

    Science.gov (United States)

    Roux, C; Fournier, B; Laugier, P; Chappard, C; Kolta, S; Dougados, M; Berger, G

    1996-08-01

    The purpose of this study was to evaluate the usefulness in osteoporosis of a new ultrasound imaging device able to create a parametric image of broadband ultrasound attenuation (BUA) at the os calcis. Three regions of interest were located in the great tuberosity of the os calcis. Precision was evaluated in 37 patients. Calcaneal bone mineral density (BMD) and BUA were compared in 33 patients. In 236 patients (including 77 with osteoporotic fractures), BUA and lumbar and femoral BMD measurements were performed. The measurements were compared using correlation coefficients. Their clinical value was estimated by comparisons of the results between patients with fractures and age-matched controls, using comparisons of the means, areas under the ROC curves, and logistic regression. Precision was in a 1.4-3.3% range. Local BUA and BMD were highly correlated (r = 0.88). Significant correlations were found between BUA and lumbar (r = 0.56) and femur (r = 0.66) BMD. In multiple regression, years since menopause and weight were significant predictors of BUA. Patients with fractures had lower BUA and BMD than age-matched controls. BUA showed the largest difference between the two populations (13-16%). Areas under the ROC curves were similar for BUA and BMD. Logistic regression after adjustment for confounding factors showed that BUA discriminated between fracture and nonfracture subjects. Broadband ultrasound attenuation imaging improves the reproducibility of ultrasound measurements. It may be useful in osteoporosis, due to its good discriminating value.

  12. Broad-Band Analysis of Polar Motion Excitations

    Science.gov (United States)

    Chen, J.

    2016-12-01

    Earth rotational changes, i.e. polar motion and length-of-day (LOD), are driven by two types of geophysical excitations: 1) mass redistribution within the Earth system, and 2) angular momentum exchange between the solid Earth (more precisely the crust) and other components of the Earth system. Accurate quantification of Earth rotational excitations has been difficult, due to the lack of global-scale observations of mass redistribution and angular momentum exchange. The over 14-years time-variable gravity measurements from the Gravity Recovery and Climate Experiment (GRACE) have provided a unique means for quantifying Earth rotational excitations from mass redistribution in different components of the climate system. Comparisons between observed Earth rotational changes and geophysical excitations estimated from GRACE, satellite laser ranging (SLR) and climate models show that GRACE-derived excitations agree remarkably well with polar motion observations over a broad-band of frequencies. GRACE estimates also suggest that accelerated polar region ice melting in recent years and corresponding sea level rise have played an important role in driving long-term polar motion as well. With several estimates of polar motion excitations, it is possible to estimate broad-band noise variance and noise power spectra in each, given reasonable assumptions about noise independence. Results based on GRACE CSR RL05 solutions clearly outperform other estimates with the lowest noise levels over a broad band of frequencies.

  13. 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.

  14. Coding metasurface for broadband microwave scattering reduction with optical transparency.

    Science.gov (United States)

    Chen, Ke; Cui, Li; Feng, Yijun; Zhao, Junming; Jiang, Tian; Zhu, Bo

    2017-03-06

    Metasurfaces have promised great possibilities in full control of the electromagnetic wavefront by spatially manipulating the phase characteristics across the interface. Here, we report a scheme to realize broadband backward scattering reduction through diffusion-like microwave reflection by utilizing a flexible indium-tin-oxide (ITO)-based ultrathin coding metasurface (less than 0.1 wavelength thick) with high optical transparence. The diffusion-like scattering is caused by the destructive interference of the scattered far-field electromagnetic wave, which is further attributed to the randomly distributed reflection phases on the metasurface composed of pre-designed meta-atoms arranged with a computer-generated pseudorandom coding sequence. Both simulation and measurement on fabricated prototype sample have been carried out to validate its performance, demonstrating a polarization-independent broadband (nearly from 8 GHz to 15 GHz) 10 dB scattering reduction with good oblique performance. The excellent performances can also be preserved to conformal cases when the flexible metasurface is uniformly wrapped around a metallic cylinder. The proposed metasurface may create new opportunities to tailor the exotic microwave scattering features with simultaneously high transmittance in visible frequencies, which could provide crucial benefits in many practical uses, such as window and solar panel applications.

  15. 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.

  16. Characterization of Large Water Clusters by Broadband Rotational Spectroscopy

    Science.gov (United States)

    Perez, Cristobal; Zaleski, Daniel P.; Seifert, Nathan A.; Pate, Brooks H.; Kisiel, Zbigniew; Temelso, Berhane; Shields, George C.; Shipman, Steven T.; Finnerman, Ian

    2013-06-01

    Most theoretical water models match with experimental result reasonably well up to n=10. For clusters larger than the decamer there is no clear consensus in the global minimum geometries, as the low-energy landscape for a given cluster size changes considerably depending on the model applied. However, there is agreement in considering the undecamer regime as one of the richer pure water cluster regimes, with a large number (>50) of isomers within 1 kcal/mol of the global minimum. Using broadband chirped-pulse Fourier transform microwave (CP-FTMW) spectroscopy operating in the 2-8 GHz frequency range, seven low-energy isomers of the water undecamer have been identified in a pulsed molecular beam. The observed water cluster structures have been identified as belonging to four families on basis to their rotational constants according to their different oxygen atom frameworks. These families can be explained by building up the structures from smaller water cluster subunits. Rotational spectra consistent with theoretical predictions for two isomers of (H_{2}O)_{13} and one of (H_{2}O)_{15} have also been identified. Due to the high density of lines observed in the broadband spectrum, the traditional method of pattern recognition using ab-initio calculations was replaced with a new approach combining high-level ab-initio calculations with automatic fitting tools. These autofitting routines were tested on these systems and are also briefly described.

  17. 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.

  18. 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....

  19. Towards a universal scaling for broadband turbulent noise in internal flow devices

    NARCIS (Netherlands)

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

    2013-01-01

    An investigation is performed on the scalability of broadband noise sources from separated flows in internal pipe systems. Broadband sources from for example wellhead chokes, bends and valves can potentially excite subsea manifolds through fluid acoustic coupling and fluid structural coupling. The

  20. 76 FR 37779 - Rural Broadband Access Loans and Loan Guarantees Program

    Science.gov (United States)

    2011-06-28

    ... Rural Utilities Service Rural Broadband Access Loans and Loan Guarantees Program AGENCY: Rural Utilities... for the Rural Broadband Access Loans and Loan Guarantees Program for fiscal year (FY) 2011. A Notice..., 2011, at 76 FR 13797, prior to the passage of a final appropriations bill identifying a definite...

  1. 77 FR 12951 - Lifeline and Link Up Reform and Modernization, Advancing Broadband Availability Through Digital...

    Science.gov (United States)

    2012-03-02

    ...] Lifeline and Link Up Reform and Modernization, Advancing Broadband Availability Through Digital Literacy... March 2, 2012 Part III Federal Communications Commission 47 CFR Chapter 54 Lifeline and Link Up Reform and Modernization, Advancing Broadband Availability Through Digital Literacy Training; Final Rule #0...

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

    Science.gov (United States)

    2012-04-20

    .... 2948] Lifeline and Link Up Reform and Modernization; Advancing Broadband Availability Through Digital... applicability. Subject: Lifeline and Link Up Reform and Modernization; Advancing Broadband Availability through Digital Literacy Training, et al., published at 77 FR 12952, March 2, 2012 in WC Docket Nos. 11-42, 03...

  3. 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

  4. 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.

  5. 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.

  6. 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

  7. Recent evolutions of the GEOSCOPE broadband seismic observatory

    Science.gov (United States)

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

    2017-04-01

    The GEOSCOPE observatory provides 35 years of continuous broadband data to the scientific community. The 32 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 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 GEOSCOPE data center and are automatically transmitted to other data centers (IRIS-DMC and RESIF) and tsunami warning centers. In 2016, a new station has been installed in Wallis and Futuna (FUTU, South-Western Pacific Ocean), and WUS station has been reinstalled in Western China. Data of the stations are technically validated by IPGP (25 stations) or EOST (6 stations) in order to check their continuity and integrity. A 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 GEOSCOPE data center in Paris. They are made available to the international scientific community through different interfaces (see details on http://geoscope.ipgp.fr). An important technical work is done to homogenize the data formats of the whole GEOSCOPE database, in order to make easier the data duplication at the IRIS-DMC and RESIF data centers. The GEOSCOPE broadband seismic observatory also provides near-real time information on the World large seismicity (above magnitude 5.5-6) through the automated application of the SCARDEC method. 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 minutes after the occurrence of the event. A specific webpage is then

  8. Broadband mid-IR subharmonic OPOs for molecular spectroscopy

    Science.gov (United States)

    Leindecker, Nick; Marandi, Alireza; Vodopyanov, Konstantin L.; Byer, Robert L.

    2012-02-01

    We generate broadband mid-infrared frequency combs via degenerate optical parametric oscillation in a subharmonic OPO. This technique efficiently transfers the desirable properties of shorter wavelength mode-locked sources to the mid- IR. Our OPO resonator is a 3m or 4m ring cavity composed of one pair of concave mirrors with R=50mm and four flat mirrors, all but one of which are gold coated with > 99% reflection. A single dielectric mirror is used to introduce the pump (2.05 micron from IMRA America, 75 MHz, 80 fs, 600mW or 1.55 micron from Menlo Systems C-fiber, 100 MHz, 70 fs, 350 mW or 1.56 micron from Toptica Photonics FemtoFiber Pro, 80 MHz, 85 fs, 380 mW). The dielectric mirror is transmissive for the pump and reflective in a 2.5- 4 micron or 3- 6 micron (for 2 micron pump) range. Broadband parametric gain around the 3.1-micron subharmonic is provided by short (0.2-0.5mm) periodically poled lithium niobate (MgO:PPLN) at Brewster angle. Crystals were cut from Crystal Technology Inc. material having QPM period of 34.8 microns for type 0 (e=e+e) phase matching at t=32 deg. C. With the 2-micron pump, orientation patterned gallium arsenide from BAE systems is used as the non-linear material In both systems, the enormous acceptance bandwidth at degeneracy, typical for OPOs with type 0 (or type I) phase-matching, gives broad bandwidth and makes temperature tuning insignificant. Broadband oscillation is achieved when signal/idler are brought into degenerate resonance by fine-tuning the cavity length with a mirror on a piezo stage. Using an 8% reflective pellicle, we outcouple a frequency comb of more than 1000nm bandwidth, centered around 3.1 microns from the Er/PPLN system. A 1mm or 2.5mm thick ZnSe plate at Brewster angle provides 2nd-order group velocity dispersion compensation, improving the OPO bandwidth. The OPO threshold was measured to be < 30mW. When locked, the OPO outputs 60 mW of average power centered at 3.1 microns. With the Tm/OP-GaAs system we

  9. Guidelines for Standardized Testing of Broadband Seismometers and Accelerometers

    Science.gov (United States)

    Hutt, Charles R.; Evans, John R.; Followill, Fred; Nigbor, Robert L.; Wielandt, Erhard

    2010-01-01

    Testing and specification of seismic and earthquake-engineering sensors and recorders has been marked by significant variations in procedures and selected parameters. These variations cause difficulty in comparing such specifications and test results. In July 1989, and again in May 2005, the U.S. Geological Survey hosted international pub-lic/private workshops with the goal of defining widely accepted guidelines for the testing of seismological inertial sensors, seismometers, and accelerometers. The Proceedings of the 2005 workshop have been published and include as appendix 6 the report of the 1989 workshop. This document represents a collation and rationalization of a single set of formal guidelines for testing and specifying broadband seismometers and accelerometers.

  10. Metamaterial-based perfect absorber: polarization insensitivity and broadband

    Science.gov (United States)

    Hien Nguyen, Thi; Bui, Son Tung; Nguyen, Trong Tuan; Nguyen, Thanh Tung; Lee, YoungPak; Nguyen, Manh An; Vu, Dinh Lam

    2014-06-01

    We report the design and simulation of a microwave metamaterials-based perfect absorber using a simple and highly symmetric structure. The basic structure consists of three functional layers: the middle is a dielectric, the back is a metallic plane and the front is a ring of metal. The influence of structural parameters on the absorbance and absorption frequency were investigated. The results show an exceptional absorption performance of near unity around 16 GHz. In addition, the absorption is insensitive to the polarization of the incident beam due to the highly symmetric structure. Finally, four and nine rings with different sizes are arranged appropriately in a unit cell in order to construct a broadband absorber. A polarization-insensitive absorbance of above 90% is achieved over a bandwidth of 15%.

  11. Broadband metamaterial for optical transparency and microwave absorption

    Science.gov (United States)

    Zhang, Cheng; Cheng, Qiang; Yang, Jin; Zhao, Jie; Cui, Tie Jun

    2017-04-01

    We present a metamaterial for simultaneous optical transparency and microwave absorption in broadband, which can be used as an optically transparent radar-wave absorber. The proposed metamaterial absorber is made of windmill-shaped elements with the reflection spectra featured by three absorption bands. By properly tailoring the resonances of the structure, we achieve the optimized metamaterial absorptivity that is greater than 90% from 8.3 to 17.4 GHz. In the meantime, excellent optical transmittance is achieved by use of the indium tin oxide (ITO) film with moderate surface resistance, implying that the optical properties of the metamaterial are hardly affected by the periodic meta-atoms. Both numerical simulations and experimental results demonstrate the good performance of the proposed metamaterial, thereby enabling a wide range of applications such as ultrathin detectors and photovoltaic solar cells in the future.

  12. Three-dimensional broadband omnidirectional acoustic ground cloak

    Science.gov (United States)

    Zigoneanu, Lucian; Popa, Bogdan-Ioan; Cummer, Steven A.

    2014-04-01

    The control of sound propagation and reflection has always been the goal of engineers involved in the design of acoustic systems. A recent design approach based on coordinate transformations, which is applicable to many physical systems, together with the development of a new class of engineered materials called metamaterials, has opened the road to the unconstrained control of sound. However, the ideal material parameters prescribed by this methodology are complex and challenging to obtain experimentally, even using metamaterial design approaches. Not surprisingly, experimental demonstration of devices obtained using transformation acoustics is difficult, and has been implemented only in two-dimensional configurations. Here, we demonstrate the design and experimental characterization of an almost perfect three-dimensional, broadband, and, most importantly, omnidirectional acoustic device that renders a region of space three wavelengths in diameter invisible to sound.

  13. Ultra-broadband carpet cloak for transverse-electric polarization

    Science.gov (United States)

    Deng, Ye; Xu, Su; Zhang, Runren; Zheng, Bin; Chen, Hua; Gao, Fei; Yu, Faxin; Zhang, Baile; Chen, Hongsheng

    2016-04-01

    Magnetism is a necessity in constructing macroscopic metamaterial invisibility cloaks that are theoretically designed by transformation optics, but will generally limit the cloaking bandwidth to an impractically narrow range. To meet the broad bandwidth demand, magnetism has been fully abandoned in previous demonstrations of macroscopic carpet cloaking, whose approach, however, cannot apply to a transverse-electric (TE) polarization. To fill this gap, here we experimentally demonstrate an ultra-broadband magnetic carpet cloak for the TE polarization. The cloak is made of non-resonant closed-ring metamaterials with little dispersion and the cloaking performance is confirmed with both time-domain simulation and frequency scanning measurement over a broad bandwidth corresponding to a pulse signal illumination.

  14. Broadband metamaterial as an "invisible" radiative cooling coat

    Science.gov (United States)

    Huang, Yijia; Pu, Mingbo; Zhao, Zeyu; Li, Xiong; Ma, Xiaoliang; Luo, Xiangang

    2018-01-01

    In this paper, we propose a compact planar device in infrared (3- 12 μm) that has a high emission range from 5 μm to 8 μm while simultaneously serving as a broadband mirror for the rest wavelengths by engineering its thermal emission characteristics. The structure utilizes a random-stacked multilayer to reduce the thickness required for ideal spectrum engineering. In addition, it is also convenient to fabricate and scale up. All the features above makes it an ;invisible; radiative cooling coat by taking advantage of the atmospheric transparency window. We believe that this device may fundamentally enable new technological possibilities for stealth techniques by integrating the device with traditional cloaking methods.

  15. Broadband opto-mechanical phase shifter for photonic integrated circuits

    Science.gov (United States)

    Guo, Xiang; Zou, Chang-Ling; Ren, Xi-Feng; Sun, Fang-Wen; Guo, Guang-Can

    2012-08-01

    A broadband opto-mechanical phase shifter for photonic integrated circuits is proposed and numerically investigated. The structure consists of a mode-carrying waveguide and a deformable non-mode-carrying nanostring, which are parallel with each other. Since the nanostring can be deflected by the optical gradient force between the waveguide and the nanostring, the effective refractive indices of the waveguide will be changed and a phase shift will be generated. The phase shift under different geometry sizes, launched powers and boundary conditions are calculated and the dynamical properties as well as the thermal noise's effect are also discussed. It is demonstrated that a π phase shift can be realized with only about 0.64 mW launched power and 50 μm long nanostring. The proposed phase shifter may find potential usage in future investigation of photonic integrated circuits.

  16. Nanoscale broadband transmission lines for spin qubit control.

    Science.gov (United States)

    Dehollain, J P; Pla, J J; Siew, E; Tan, K Y; Dzurak, A S; Morello, A

    2013-01-11

    The intense interest in spin-based quantum information processing has caused an increasing overlap between the two traditionally distinct disciplines of magnetic resonance and nanotechnology. In this work we discuss rigorous design guidelines to integrate microwave circuits with charge-sensitive nanostructures, and describe how to simulate such structures accurately and efficiently. We present a new design for an on-chip, broadband, nanoscale microwave line that optimizes the magnetic field used to drive a spin-based quantum bit (or qubit) while minimizing the disturbance to a nearby charge sensor. This new structure was successfully employed in a single-spin qubit experiment, and shows that the simulations accurately predict the magnetic field values even at frequencies as high as 30 GHz.

  17. Study on electrical impedance matching for broadband ultrasonic transducer

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Geon Woo [University of Science and Technology, Daejeon (Korea, Republic of); Kim, Ki Bok [Korea Research Institute of Standards and Science, Center for Safety Measurement, Daejeon (Korea, Republic of); Baek, Kwang Sae [Elache Co., Busan (Korea, Republic of)

    2017-02-15

    Ultrasonic transducers with high resolution and resonant frequency are required to detect small defects (less than hundreds of μm) by ultrasonic testing. The resonance frequency and resolution of an ultrasonic transducer are closely related to the thickness of piezo-electric materials, backing materials, and the electric impedance matching technique. Among these factors, electrical impedance matching plays an important role because it can reduce the loss and reflection of ultrasonic energy differences in electrical impedance between an ultrasonic transducer and an ultrasonic defects detecting system. An LC matching circuit is the most frequently used electric matching method. It is necessary for the electrical impedance of an ultrasonic transducer to correspond to approximately 50 Ω to compensate the difference in electrical impedance between both connections. In this study, a 15 MHz immersion ultrasonic transducer was fabricated and an LC electrical impedance circuit was applied to that for having broad-band frequency characteristic.

  18. Broadband infrared vibrational nano-spectroscopy using thermal blackbody radiation.

    Science.gov (United States)

    O'Callahan, Brian T; Lewis, William E; Möbius, Silke; Stanley, Jared C; Muller, Eric A; Raschke, Markus B

    2015-12-14

    Infrared vibrational nano-spectroscopy based on scattering scanning near-field optical microscopy (s-SNOM) provides intrinsic chemical specificity with nanometer spatial resolution. Here we use incoherent infrared radiation from a 1400 K thermal blackbody emitter for broadband infrared (IR) nano-spectroscopy. With optimized interferometric heterodyne signal amplification we achieve few-monolayer sensitivity in phonon polariton spectroscopy and attomolar molecular vibrational spectroscopy. Near-field localization and nanoscale spatial resolution is demonstrated in imaging flakes of hexagonal boron nitride (hBN) and determination of its phonon polariton dispersion relation. The signal-to-noise ratio calculations and analysis for different samples and illumination sources provide a reference for irradiance requirements and the attainable near-field signal levels in s-SNOM in general. The use of a thermal emitter as an IR source thus opens s-SNOM for routine chemical FTIR nano-spectroscopy.

  19. Auditory brainstem response recording to multiple interleaved broadband chirps.

    Science.gov (United States)

    Cebulla, Mario; Stürzebecher, Ekkehard; Don, Manuel; Müller-Mazzotta, Jochen

    2012-01-01

    The simultaneous application of multiple stimuli that excite different frequency regions of the cochlea is a well-established method for recording frequency-specific auditory steady state responses. Because the stimuli are applied at different repetition rates, they actually do not appear exactly simultaneously. There is always a certain time difference between the multiple frequency-specific stimuli. This is true also for multiple interleaved broadband stimuli. Therefore, because of this time difference, one may expect a successful recording of responses to multiple broadband chirp stimuli even when such stimuli activate the whole cochlear partition. This article describes a technique for recording auditory brainstem responses evoked by trains of broadband chirps presented simultaneously at equal stimulus levels but at different repetition rates. The interactions between the interleaved stimulus trains were studied to lay the foundation for a rapid method of assessing temporal aspects of peripheral auditory processing. The first step in laying this foundation is to determine the characteristics of responses from an intact and normal-hearing system to these interleaved chirp trains. Subsequently, the studied interactions between the interleaved applied stimuli may provide a referential framework for future clinical studies aimed at assessing pathological populations. Two chirp trains were applied concurrently at the same stimulus level but at different repetition rates of 20/sec and 22/sec, respectively. Two overall stimulus levels were investigated: 50 and 30 dB nHL. Because of the 2 Hz difference between the repetition rates, the time difference between the stimuli of the two stimulus trains followed a periodic cycling. The cycling period of 0.5 sec contained ten 20/sec stimuli and eleven 22/sec-stimuli. The response to a single train of chirps with the repetition rate of 20/sec was also recorded. The test group consisted of 11 young adult subjects, all with

  20. Broadband degenerate OPO for mid-infrared frequency comb generation.

    Science.gov (United States)

    Leindecker, Nick; Marandi, Alireza; Byer, Robert L; Vodopyanov, Konstantin L

    2011-03-28

    We present a new technique suitable for generating broadband phase- and frequency-locked frequency combs in the mid-infrared. Our source is based on a degenerate optical parametric oscillator (OPO) which rigorously both down-converts and augments the spectrum of a pump frequency comb provided by a commercial mode-locked near-IR laser. Low intracavity dispersion, combined with extensive cross-mixing of comb components, results in extremely broad instantaneous mid-IR bandwidths. We achieve an output power of 60 mW and 20 dB bandwidth extending from 2500 to 3800 nm. Among other applications, such a source is well-suited for coherent Fourier-transform spectroscopy in the absorption-rich mid-IR 'molecular fingerprint' region.

  1. Broadband image sensor array based on graphene-CMOS integration

    Science.gov (United States)

    Goossens, Stijn; Navickaite, Gabriele; Monasterio, Carles; Gupta, Shuchi; Piqueras, Juan José; Pérez, Raúl; Burwell, Gregory; Nikitskiy, Ivan; Lasanta, Tania; Galán, Teresa; Puma, Eric; Centeno, Alba; Pesquera, Amaia; Zurutuza, Amaia; Konstantatos, Gerasimos; Koppens, Frank

    2017-06-01

    Integrated circuits based on complementary metal-oxide-semiconductors (CMOS) are at the heart of the technological revolution of the past 40 years, enabling compact and low-cost microelectronic circuits and imaging systems. However, the diversification of this platform into applications other than microcircuits and visible-light cameras has been impeded by the difficulty to combine semiconductors other than silicon with CMOS. Here, we report the monolithic integration of a CMOS integrated circuit with graphene, operating as a high-mobility phototransistor. We demonstrate a high-resolution, broadband image sensor and operate it as a digital camera that is sensitive to ultraviolet, visible and infrared light (300-2,000 nm). The demonstrated graphene-CMOS integration is pivotal for incorporating 2D materials into the next-generation microelectronics, sensor arrays, low-power integrated photonics and CMOS imaging systems covering visible, infrared and terahertz frequencies.

  2. A new parameterization of spectral and broadband ocean surface albedo.

    Science.gov (United States)

    Jin, Zhonghai; Qiao, Yanli; Wang, Yingjian; Fang, Yonghua; Yi, Weining

    2011-12-19

    A simple yet accurate parameterization of spectral and broadband ocean surface albedo has been developed. To facilitate the parameterization and its applications, the albedo is parameterized for the direct and diffuse incident radiation separately, and then each of them is further divided into two components: the contributions from surface and water, respectively. The four albedo components are independent of each other, hence, altering one will not affect the others. Such a designed parameterization scheme is flexible for any future update. Users can simply replace any of the adopted empirical formulations (e.g., the relationship between foam reflectance and wind speed) as desired without a need to change the parameterization scheme. The parameterization is validated by in situ measurements and can be easily implemented into a climate or radiative transfer model.

  3. A reflective-backing-free metamaterial absorber with broadband response

    Science.gov (United States)

    Xu, Cuilian; Qu, Shaobo; Wang, Jiafu; Yan, Mingbao; Pang, Yongqiang; Wang, Wenjie; Ma, Hua

    In this paper, we propose a polarization-independent and broadband perfect infrared (IR) metamaterial absorber (MA) without reflective backing. The proposed absorber is a periodic meta-atom array consisting of metal-dielectric-multilayer truncated cones which can absorb 80% EM wave from 50.70 to 81.87THz, while transmit 80% EM wave from 0 to 37.71THz. With the decreasing of frequency, the transmissivity increases, which is close to 100% from 0 to 5THz. We can broaden the absorption bandwidth of the MA by cascading multi-layers truncated cones. Furthermore, the proposed IR MA promises to be one desirable stealth material for radar-IR compatibility.

  4. 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...

  5. 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.

  6. Broadband quantitative NQR for authentication of vitamins and dietary supplements

    Science.gov (United States)

    Chen, Cheng; Zhang, Fengchao; Bhunia, Swarup; Mandal, Soumyajit

    2017-05-01

    We describe hardware, pulse sequences, and algorithms for nuclear quadrupole resonance (NQR) spectroscopy of medicines and dietary supplements. Medicine and food safety is a pressing problem that has drawn more and more attention. NQR is an ideal technique for authenticating these substances because it is a non-invasive method for chemical identification. We have recently developed a broadband NQR front-end that can excite and detect 14N NQR signals over a wide frequency range; its operating frequency can be rapidly set by software, while sensitivity is comparable to conventional narrowband front-ends over the entire range. This front-end improves the accuracy of authentication by enabling multiple-frequency experiments. We have also developed calibration and signal processing techniques to convert measured NQR signal amplitudes into nuclear spin densities, thus enabling its use as a quantitative technique. Experimental results from several samples are used to illustrate the proposed methods.

  7. Generalized Broadband Beamforming Using a Modal Subspace Decomposition

    Directory of Open Access Journals (Sweden)

    Rodney A. Kennedy

    2007-01-01

    Full Text Available We propose a new broadband beamformer design technique which produces an optimal receiver beam pattern for any set of field measurements in space and time. The modal subspace decomposition (MSD technique is based on projecting a desired pattern into the subspace of patterns achievable by a particular set of space-time sampling positions. This projection is the optimal achievable pattern in the sense that it minimizes the mean-squared error (MSE between the desired and actual patterns. The main advantage of the technique is versatility as it can be applied to both sparse and dense arrays, nonuniform and asynchronous time sampling, and dynamic arrays where sensors can move throughout space. It can also be applied to any beam pattern type, including frequency-invariant and spot pattern designs. A simple extension to the technique is presented for oversampled arrays, which allows high-resolution beamforming whilst carefully controlling input energy and error sensitivity.

  8. 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.

  9. Omnidirectional broadband insulating device for flexural waves in thin plates

    CERN Document Server

    Climente, Alfonso; Sánchez-Dehesa, José

    2013-01-01

    This work presents a gradient index device for insulating from vibrations a circular area of a thin plate. The gradient of the refractive index is achieved by locally changing the thickness of the plate, exploiting in this way the thickness-dependence of the dispersion relation of flexural waves in thin plates. A well-like thickness profile in an annular region of the plate is used to mimic the combination of an attractive and repulsive potentials, focusing waves at its bottom and dissipating them by means of a properly designed absorptive layer placed on top of the plate. The central area is therefore isolated from vibrations while they are dissipated at the bottom of the well. Simulations have been done using the multilayer multiple scattering method and the results prove their broadband efficiency and omnidirectional properties.

  10. A novel broadband bi-mode active frequency selective surface

    Science.gov (United States)

    Xu, Yang; Gao, Jinsong; Xu, Nianxi; Shan, Dongzhi; Song, Naitao

    2017-05-01

    A novel broadband bi-mode active frequency selective surface (AFSS) is presented in this paper. The proposed structure is composed of a periodic array of convoluted square patches and Jerusalem Crosses. According to simulation results, the frequency response of AFSS definitely exhibits a mode switch feature between band-pass and band-stop modes when the diodes stay in ON and OFF states. In order to apply a uniform bias to each PIN diode, an ingenious biasing network based on the extension of Wheatstone bridge is adopted in prototype AFSS. The test results are in good agreement with the simulation results. A further physical mechanism of the bi-mode AFSS is shown by contrasting the distribution of electric field on the AFSS patterns for the two working states.

  11. A novel broadband bi-mode active frequency selective surface

    Directory of Open Access Journals (Sweden)

    Yang Xu

    2017-05-01

    Full Text Available A novel broadband bi-mode active frequency selective surface (AFSS is presented in this paper. The proposed structure is composed of a periodic array of convoluted square patches and Jerusalem Crosses. According to simulation results, the frequency response of AFSS definitely exhibits a mode switch feature between band-pass and band-stop modes when the diodes stay in ON and OFF states. In order to apply a uniform bias to each PIN diode, an ingenious biasing network based on the extension of Wheatstone bridge is adopted in prototype AFSS. The test results are in good agreement with the simulation results. A further physical mechanism of the bi-mode AFSS is shown by contrasting the distribution of electric field on the AFSS patterns for the two working states.

  12. Energy savings in mobile broadband network based on load predictions

    DEFF Research Database (Denmark)

    Samulevicius, Saulius; Pedersen, Torben Bach; Sørensen, Troels Bundgaard

    2012-01-01

    in wireless networks. To save energy in MBNs, one of the options is to turn off parts of the network equipment in areas where traffic falls below a specific predefined threshold. This paper looks at a methodology for identifying periods of the day when cells or sites carrying low traffic are candidates...... for being totally or partly switched off, given that the decrease in service quality can be controlled gracefully when the sites are switched off. Based on traffic data from an operational network, potential average energy savings of approximately 30% with some few low traffic cells/sites reaching up to 99......Abstract—The deployment of new network equipment is resulting in increasing energy consumption in mobile broadband networks (MBNs). This contributes to higher CO2 emissions. Over the last 10 years MBNs have grown considerably, and are still growing to meet the evolution in traffic volume carried...

  13. 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).

  14. O2 (1Δg) detection using broadband CARS

    Science.gov (United States)

    Liu, Jinbo; Guo, Jingwei; Cai, Xianglong; Gai, Baodong; Meng, Qingkun; Jin, Yuqi

    2015-02-01

    1 Δg oxygen was the active medium of chemical oxygen iodine laser (COIL), the concentration and distribution of 1 Δg oxygen was important for the output power and beam quality. However, the current test technique, such as fluorescence detection method, absorption spectrum method could not get accurate 1 Δg oxygen information, due to the interference from the iodine fluorescence or the rigorous request of the laser source and optics and detection elements. The anti-stokes Raman spectrum of 1 Δg oxygen was regarded as a potential technique to obtain desirable signal, and the coherent anti-stokes Raman scatter (CARS) was the most feasible technique to get better signal to noise ratio (SNR). In this paper, we reported a broadband nanosecond coherent anti-stokes Raman scatter (CARS) detecting system built up for the detection of the concentration and distribution of O2( 1 Δg) in COIL:The second harmonic of a Nd: YAG pulse laser was separated into two parts, one part was used to pump a broadband nanosecond dye laser to generate light of 578-580 nm, which covered both stokes lines of O2 ( 1 Δg)and O2 (3 ∑) The other part was combined with dye laser output by a dichroic mirror, and then introduced into the detection region of COIL through a focus lens. CARS signals for O2(1 Δg)and O2 (3 ∑)have different wavelengths, and their intensity was proportional to the square of the concentration of O2(1 Δg) and O2( 3 ∑). By changing the focus spot of pump and stokes laser, the concentration distribution of O2(1 Δg) and O2(3 ∑)at different position could be obtained.

  15. Broadband Measurement of Aerosol Extinction in the Visible Range

    Science.gov (United States)

    He, Quanfu; Bluvshtein, Nir; Segev, Lior; Flores, Michel; Rudich, Yinon; Washenfelder, Rebecca; Brown, Steven

    2017-04-01

    Atmospheric aerosols influence the Earth's radiative budget directly by scattering and absorbing incoming solar radiation. Aerosol direct forcing remains one of the largest uncertainties in quantifying the role that aerosols play in the Earth's radiative budget. The optical properties of aerosols vary as a function of wavelength, but few measurements reported the wavelength dependence of aerosol extinction cross section and complex refractive indices, particularly in the blue and visible spectral range. There is also currently a large gap in our knowledge of how the optical properties evolve as a function of atmospheric aging in the visible spectrum. In this study, we constructed a new and novel laboratory instrument to measure aerosol extinction as a function of wavelength, using cavity enhanced spectroscopy with a white light source. This broadband cavity enhanced spectroscopy (BBCES) covers the 395-700 nm spectral region using a broadband light source and a grating spectrometer with charge-coupled device detector (CCD). We evaluated this BBCES by measuring extinction cross section for aerosols that are pure scattering, slightly absorbing and strongly absorbing atomized from standard materials. We also retrieved the refractive indices from the measured extinction cross sections. Secondary organic aerosols from biogenic and anthropogenic precursors were "aged" to differential time scales (1 to 10 days) in an Oxidation Flow Reactor (OFR) under the combined influence of OH, O3 and UV light. The new BBCES was used to online measure the extinction cross sections of the SOA. This talk will provide a comprehensive understanding of aerosol optical properties alerting during aging process in the 395 - 700 nm spectrum.

  16. Fast and precise data acquisition for broadband microwave tomography systems

    Science.gov (United States)

    Mallach, Malte; Musch, Thomas

    2017-09-01

    Microwave imaging (MWI) is a noninvasive diagnosis method, which has been investigated for a wide range of applications. MWI techniques include radar-based approaches as well as microwave tomography (MWT). One major challenge designing broadband MWI systems is the development of a data acquisition unit that allows for fast broadband scattering parameter measurements with a high measurement precision and a high dynamic range (DR), at reasonable cost. The cost-performance criteria cannot readily be achieved using commercial, continuous wave (CW) vector network analyzers (VNA) or pulse-based systems. Therefore, in this paper we propose a data acquisition unit, based on the well-known method of frequency modulated continuous wave (FMCW) network analysis. It offers fast scattering parameter measurements without compromising the measurement precision and the DR, and is particularly advantageous for MWI systems requiring a high number of frequency samples. A 2-port metadyne prototype electronics with low hardware complexity was developed, which allows very fast, precise, and accurate reflection and transmission measurements in the frequency range from 0.5 GHz to 5.5 GHz. To the best of the authors’ knowledge, a system with combined performance in terms of bandwidth, sweep time (1 ms), DR (80 dB) and maximum signal-to-noise-and-spurious ratio (65 dB) has not previously been reported. The design, the calibration, and the characterization of the prototype electronics are described in detail, and the measurement results are compared to those obtained with commercial high-end CW VNA. The advantages and limitations of the metadyne FMCW technique compared to the heterodyne CW technique are discussed. The applicability of the prototype electronics and the described calibration technique for microwave imaging has been demonstrated based on measurements using an 8-port MWT sensor and a switching matrix.

  17. 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.

  18. 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.

  19. Broadband supercontinuum light source seeded by random distributed feedback fiber laser

    Science.gov (United States)

    Ma, R.; Rao, Y. J.; Zhang, W. L.; Wu, H.; Zeng, X.

    2017-04-01

    A novel broadband light source based on supercontinuum (SC) generation seeded by random distributed feedback fiber laser (RFL) is proposed and demonstrated for the first time. A half-opened fiber cavity formed by FBG and TrueWave fiber is used to generate random lasing and SC simultaneously. Experimental results indicate that RFL can be used as an effective pump for generation of SC. SC with 20-dB bandwidth of >250 nm was obtained. Such a broadband SC light source seeded by RFL may pave a way to generate high power broadband RFLs for use in optical sensing and measurement.

  20. 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

  1. New Broadband LIDAR for Greenhouse Carbon Dioxide Gas Sensing in the Earth's Atmosphere

    Science.gov (United States)

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

    2011-01-01

    We present demonstration of a novel broadband lidar technique capable of dealing with the atmospherically induced variations in CO2 absorption using a Fabry-Perot based detector and a broadband laser. The Fabry-Perot solid etalon in the receiver part is tuned to match the wavelength of several CO2 absorption lines simultaneously. The broadband technique tremendously reduces the requirement for source wavelength stability, instead putting this responsibility on the Fabry- Perot based receiver. The instrument technology we are developing has a clear pathway to space and realistic potential to become a robust, low risk space measurement system.

  2. 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.

  3. Ultimate VHF Broadband Interferometer Zen KAWASAKI and Manabu AKITA

    Science.gov (United States)

    Kawasaki, Z.; Akita, M.

    2013-12-01

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

  4. 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 (<1 s to 100 s). Moving towards an instrument pool composed entirely of direct burial sensors (some with integrated digitizers) could yield higher

  5. 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

  6. Enabling mobile/wireless broadband technologies and services for the next billion users

    CSIR Research Space (South Africa)

    Mekuria, F

    2011-09-01

    Full Text Available As wireless devices and the useful services they can deliver become more pervasive and affordable; the need for wireless broadband technologies meeting the demands of emerging market countries is growing. In this paper the technology choice...

  7. 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...

  8. Broadband Energy Harvester Using Non-linear Polymer Spring and Electromagnetic/Triboelectric Hybrid Mechanism

    National Research Council Canada - National Science Library

    Rahul Kumar Gupta; Qiongfeng Shi; Lokesh Dhakar; Tao Wang; Chun Huat Heng; Chengkuo Lee

    2017-01-01

    .... In this work, we investigate a broadband energy harvester based on combination of non-linear stiffening effect and multimodal energy harvesting to obtain high bandwidth over wide range of accelerations (0.1 g-2.0 g...

  9. Improving rural broadband deployment with synergistic effects between multiple fixed infrastructures

    Directory of Open Access Journals (Sweden)

    Felix Limbach

    2016-10-01

    This paper explores cost savings that can be achieved if national non-telecommunication infrastructures are considered as source for broadband networks in rural areas. Moreover, it assesses economic, political and regulatory measures required for improving synergy utilization. The presented approach is based on a techno-economic broadband deployment model, which is applied to all rural communities in Germany. Results indicate that synergy optimized network topologies can generally decrease rural broadband deployment cost. However, it is required that local authorities recognize the definition of broadband tender areas as a chance for the aggregation of demand. Moreover, national regulators need to ensure that metro-aggregation, backbone and co-location costs, which are associated with non-telecommunication infrastructures, do not exceed the costs of the incumbent by more than 50%.

  10. 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...

  11. 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 as...

  12. Systematic Approach for Design of Broadband, High Efficiency, High Power RF Amplifiers

    National Research Council Canada - National Science Library

    Mohadeskasaei, Seyed Alireza; An, Jianwei; Chen, Yueyun; Li, Zhi; Abdullahi, Sani Umar; Sun, Tie

    2017-01-01

    ...‐AB RF amplifiers with high gain flatness. It is usually difficult to simultaneously achieve a high gain flatness and high efficiency in a broadband RF power amplifier, especially in a high power design...

  13. Broadband as a factor of development: a challenge for Mexican digital agenda

    Directory of Open Access Journals (Sweden)

    Delia CROVI DRUETTA

    2012-02-01

    Full Text Available This article aims to analyze the importance of broadband as a development issue that has been highlighted at regional and international meetings. As a result of these concerns, in 2010 UNESCO and ITU set up the Broadband Digital Development Commision aimed at promoting the use of this resource related to the objectives of development Goals, Mgs, as proposed by the United Nations Development Programme, UNDP. Data is also provided regarding the broadband in Mexico, availability of factors support the view that there exists a digital division in this area and the absence of public policies consider it a factor of development. Working together explains beyond broadband access and positioned as a key player in processes of technological appropriation that encourage social and cultural changes.

  14. Optimization of photonic crystal 60 degrees waveguide bends for broadband and slow-light transmission

    DEFF Research Database (Denmark)

    Lavrinenko, Andrei; Tetu, Amelie; Frandsen, Lars Hagedorn

    2007-01-01

    We present results on broadband transmission through photonic crystal waveguide bends optimized for slowlight modes. Theoretical analysis and topology optimization are complemented by experimental verification of designs fabricated in SOI material....

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

    National Research Council Canada - National Science Library

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

    2013-01-01

    .... Here, we show the use of broadband light-absorbing nanoparticles as solar photothermal heaters, which generate high-temperature steam for a standalone, efficient solar autoclave useful for sanitation...

  16. 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...

  17. Characteristics of a Broadband Dye Laser Using Pyrromethene and Rhodamine Dyes

    Science.gov (United States)

    Tedder, Sarah A.; Danehy, Paul M.; Wheeler, Jeffrey L.

    2011-01-01

    A broadband dye laser pumped by a frequency-doubled Nd:YAG laser with a full-width half-maximum (FWHM) from 592 to 610 nm was created for the use in a dual-pump broadband CARS system called WIDECARS. The desired broadband dye laser was generated with a mixture of Pyrromethene dyes as an oscillator gain medium and a spectral selective optic in the oscillator cavity. A mixture of Rhodamine dyes were used in the amplifier dye cell. To create this laser a study was performed to characterize the spectral behavior of broadband dye lasers created with Rhodamine dyes 590, 610, and 640, Pyrromethene dyes 597 and 650 as well as mixture of these dyes.

  18. Large-area broadband saturable Bragg reflectors by use of oxidized AlAs.

    Science.gov (United States)

    Tandon, S N; Gopinath, J T; Shen, H M; Petrich, G S; Kolodziejski, L A; Kärtner, F X; Ippen, E P

    2004-11-01

    Broadband saturable Bragg reflectors (SBRs) are designed and fabricated by monolithic integration of semiconductor saturable absorbers with broadband Bragg mirrors. The wet oxidation of AlAs creates low-index AlxOy layers for broadband, high-index-contrast AlGaAs/AlxOy or InGaAlP/AlxOy mirrors. SBR mirror designs indicate greater than 99% reflectivity over bandwidths of 294, 466, and 563 nm for center wavelengths of 800, 1300, and 1550 nm, respectively. Highly strained and unstrained absorbers are stably integrated with the oxidized mirrors. Large-scale lateral oxidation techniques permit the fabrication of SBRs with diameters of 500 microm. Large-area, broadband SBRs are used to self-start and mode lock a variety of laser systems at wavelengths from 800 to 1550 nm.

  19. Near-unity broadband absorption designs for semiconducting nanowire arrays via localized radial mode excitation

    National Research Council Canada - National Science Library

    Fountaine, Katherine T; Kendall, Christian G; Atwater, Harry A

    2014-01-01

    ...We report design methods for achieving near-unity broadband light absorption in sparse nanowire arrays, illustrated by results for visible absorption in GaAs nanowires on Si substrates. Sparse (5% fill fraction...

  20. Spectrum database as a service (SDaaS) for broadband innovation and efficient spectrum utilization

    CSIR Research Space (South Africa)

    Mfupe, L

    2013-10-01

    Full Text Available Broadband innovations for future wireless networks involves rapid sharing of radio frequency (RF) spectrum resources by means of dynamic spectrum access techniques (DSA) to satisfy immediate portfolio of heterogeneous demands of wireless IP services...

  1. 77 FR 22762 - Proposed Information Collection; Comment Request; State Broadband Data and Development Grant...

    Science.gov (United States)

    2012-04-17

    ... National Telecommunications and Information Administration Proposed Information Collection; Comment Request; State Broadband Data and Development Grant Program Progress Report AGENCY: National Telecommunications... collections, as required by the Paperwork Reduction Act of 1995. DATES: Written comments must be submitted on...

  2. 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.

  3. Optimization of Photonic Crystal 60o Waveguide Bends in the Slow Light Regime for Broadband Transmission

    DEFF Research Database (Denmark)

    Lavrinenko, Andrei; Têtu, Amélie; Frandsen, Lars Hagedorn

    2006-01-01

    We present results for broadband transmission through photonic crystal waveguide bends optimized for slow-light modes. Theoretical analysis is complemented by experimental verification of designs including topology optimized ones fabricated in SOI material.......We present results for broadband transmission through photonic crystal waveguide bends optimized for slow-light modes. Theoretical analysis is complemented by experimental verification of designs including topology optimized ones fabricated in SOI material....

  4. Ultra-broadband optical signal processing using AlGaAs-OI devices

    DEFF Research Database (Denmark)

    Galili, Michael; Da Ros, Francesco; Hu, Hao

    2017-01-01

    Aluminum Gallium Arsenide on insulator (AlGaAs-OI) has recently been developed into a very attractive platform for optical signal processing. This paper reviews key results of broadband optical signal processing using this platform.......Aluminum Gallium Arsenide on insulator (AlGaAs-OI) has recently been developed into a very attractive platform for optical signal processing. This paper reviews key results of broadband optical signal processing using this platform....

  5. Telecommunications and Internet Broadband Policy: Sorting Out the Pieces for Telerehabilitation

    OpenAIRE

    Seelman, Katherine D.

    2010-01-01

    Technological change is accelerating and with it regulatory upheaval. Most of us agree that providing universal telecommunication services to all our citizens is a worthy ideal. Nonetheless, many of us do not agree that regulation should be the means to make broadband Internet services widely available. This Viewpoint begins sorting out pieces of the emerging United States, regulatory and policy puzzle for broadband Internet with an eye to the interests of telerehabilitation providers and con...

  6. 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.

  7. Broadband black phosphorus optical modulator in visible to mid-infrared spectral range

    OpenAIRE

    ZHANG, Rui; Zhang, Yuxia; Yu, Haohai; Zhang, Huaijin; Yang, Ruinong; Yang, Bingchao; Liu, Zhongyuan; Wang, Jiyang

    2015-01-01

    Black phosphorous (BP), a two-dimensional (2D) material, has a direct bandgap, which fills up the bandgap lacuna left by graphene topological insulators and transition-metal dichalcogenides because of its dependence on the layers and applied strains. Theoretically, the direct and tunable band gap indicates the broadband applications in optoelectronics with high efficiencies in the spectral range from visible to mid-infrared. Here, a BP broadband optical modulator is experimentally constructed...

  8. Low Profile Antenna Performance Study Part 2. Broadband Antenna Techniques Survey

    Science.gov (United States)

    1977-10-01

    shaped radiators, presented in the literature [141, [15], and depicted in Figs. 3b and c, resemble the biconical antenna and Alford’s tapered-horn...V Research and Development Technical Report .ECOM-4542 LOW PROFILE ANTENNA PERFORMANCE STUDY PART I1: BROADBAND ANTENNA TECHNIQUES SURVEY C. M...Small antenna , low-profile antenna , broadband matching, folded antennas , multi- element antennas , antenna loading. 90. ABSTRACT (Conlinu en revere, side

  9. On the Design of Conical Antennas for Broadband Impedance Matching Performance

    OpenAIRE

    Francisco Estêvão Simão Pereira; Maurício Henrique Costa Dias

    2017-01-01

    In the scope of broadband radiators, the biconical antenna, or its monopole conical counterpart, is long known to be a proper choice. One common form of such radiator, the spherically capped conical antenna (SCCA), has closed-form solution to its input impedance, from which the broadband performance potential is easily verified. Nonetheless, from the design perspective, apart from a few clues inferred from existing solutions, little is found to accurately guide the choice of the main geometri...

  10. Are Classroom Internet Use and Academic Performance Higher after Government Broadband Subsidies to Primary Schools?

    OpenAIRE

    Hyland, Marie; Layte, Richard; Lyons, Seán; McCoy, Selina; Silles, Mary

    2015-01-01

    This paper combines data from a government programme providing broadband access to primary schools in Ireland with survey microdata on schools', teachers' and pupils use of the internet to examine the links between public subsidies, classroom use of the internet and educational performance. Provision of broadband service under a government scheme was associated with more than a doubling of teachers' use of the internet in class after about a two year lag. Better computing facilities in school...

  11. Broadband Reflectionless Metasheets: Frequency-Selective Transmission and Perfect Absorption

    Directory of Open Access Journals (Sweden)

    V. S. Asadchy

    2015-07-01

    Full Text Available Energy of propagating electromagnetic waves can be fully absorbed in a thin lossy layer, but only in a narrow frequency band, as follows from the causality principle. On the other hand, it appears that there are no fundamental limitations on broadband matching of thin resonant absorbing layers. However, known thin absorbers produce significant reflections outside of the resonant absorption band. In this paper, we explore possibilities to realize a thin absorbing layer that produces no reflected waves in a very wide frequency range, while the transmission coefficient has a narrow peak of full absorption. Here we show, both theoretically and experimentally, that a thin resonant absorber, invisible in reflection in a very wide frequency range, can be realized if one and the same resonant mode of the absorbing array unit cells is utilized to create both electric and magnetic responses. We test this concept using chiral particles in each unit cell, arranged in a periodic planar racemic array, utilizing chirality coupling in each unit cell but compensating the field coupling at the macroscopic level. We prove that the concept and the proposed realization approach also can be used to create nonreflecting layers for full control of transmitted fields. Our results can have a broad range of potential applications over the entire electromagnetic spectrum including, for example, perfect ultracompact wave filters and selective multifrequency sensors.

  12. Broadband laser ranging precision and accuracy experiments with PDV benchmarking

    Science.gov (United States)

    Catenacci, Jared; Daykin, Ed; Howard, Marylesa; Lalone, Brandon; Miller, Kirk

    2017-06-01

    Broadband laser ranging (BLR) is a developmental diagnostic designed to measure the precise position of surfaces and particle clouds moving at velocities of several kilometers per second. Recent single stage gas gun experiments were conducted to quantify the precision and accuracy possible with a typical BLR system. For these experiments, the position of a mirrored projectile is measured relative to the location of a stationary optical flat (uncoated window) mounted within the gun catch tank. Projectile velocity is constrained to one-dimensional motion within the gun barrel. A collimating probe is aligned to be orthogonal to both the target window and the mirrored impactor surface. The probe is used to simultaneously measure the position and velocity with a BLR and conventional Photonic Doppler Velocimetry (PDV) system. Since there is a negligible lateral component to the target velocity, coupled with strong signal returns from a mirrored surface, integrating the PDV measurement provides a high fidelity distance measurement reference to which the BLR measurement may be compared.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Broadband architecture for galvanically accessible superconducting microwave resonators

    Science.gov (United States)

    Bosman, Sal J.; Singh, Vibhor; Bruno, Alessandro; Steele, Gary A.

    2015-11-01

    In many hybrid quantum systems, a superconducting circuit is required, which combines DC-control with a coplanar waveguide (CPW) microwave resonator. The strategy thus far for applying a DC voltage or current bias to microwave resonators has been to apply the bias through a symmetry point in such a way that it appears as an open circuit for certain frequencies. Here, we introduce a microwave coupler for superconducting CPW cavities in the form of a large shunt capacitance to ground. Such a coupler acts as a broadband mirror for microwaves while providing galvanic connection to the center conductor of the resonator. We demonstrate this approach with a two-port λ/4-transmission resonator with linewidths in the MHz regime ( Q ˜103 ) that shows no spurious resonances and apply a voltage bias up to 80 V without affecting the quality factor of the resonator. This resonator coupling architecture, which is simple to engineer, fabricate, and analyse, could have many potential applications in experiments involving superconducting hybrid circuits.

  18. Broadband laser ranging development at the DOE Labs

    Science.gov (United States)

    Bennett, Corey V.; La Lone, Brandon M.; Younk, Patrick W.; Daykin, Ed P.; Rhodes, Michelle A.

    2017-02-01

    Broadband Laser Ranging (BLR) is a new diagnostic being developed in collaboration across multiple USA Dept. of Energy (DOE) facilities. Its purpose is to measure the precise position of surfaces and particle clouds moving at speeds of a few kilometers per second. The diagnostic uses spectral interferometry to encode distance into a modulation in the spectrum of pulses from a mode-locked fiber laser and uses a dispersive Fourier transformation to map the spectral modulation into time. This combination enables recording of range information in the time domain on a fast oscilloscope every 25-80 ns. Discussed here are some of the hardware design issues, system tradeoffs, calibration issues, and experimental results. BLR is being developed as an add-on to conventional Photonic Doppler Velocimetry (PDV) systems because PDV often yields incomplete information when lateral velocity components are present, or when there are drop-outs in the signal amplitude. In these cases, integration of the velocity from PDV can give incorrect displacement results. Experiments are now regularly fielded with over 100 channels of PDV, and BLR is being developed in a modular way to enable high channel counts of BLR and PDV recorded from the same probes pointed at the same target location. In this way instruments, will independently record surface velocity and distance information along the exact same path.

  19. 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.

  20. Broadband homodyne reflectometer devoted to density fluctuation measurements

    Energy Technology Data Exchange (ETDEWEB)

    Estrada, T.; Sanchez, J.; Branas, B.; Navarro, A.P. (Asociacion EURATOM/CIEMAT, 28040 Madrid (Spain))

    1990-10-01

    A microwave reflectometer has been used in the TJ-I tomakak ({ital R}=0.30 m, {ital a}=0.10 m, {ital I}{sub {ital p}I{ital p}}{lt} 50 kA, {ital B}{sub {ital t}} {lt} 1.5 T) to monitor density fluctuations in the plasma bulk. Experiments were made in the range 33--50 GHz, {ital x} mode. The system uses a single antenna for launching and receiving the microwave beam. Since broadband operation usually requires homodyne detection, different techniques were used to overcome the limitations due to this detection scheme. Radial profiles of the density turbulence were taken and the behavior of the spectra analyzed. A slow frequency sweeping has been performed to provide a method to normalize the signals reflected from different radial positions. In addition this technique can be used to obtain information on the absolute value of the phase oscillation amplitude. Spectra of the edge density fluctuations obtained by reflectometry and by Langmuir probes are compared. By the use of two reflectometers in the same antenna, radial correlation experiments can be performed. Some discussions on the ability of homodyne reflectometry to determine coherence lengths are also presented. A slow sweeping of the frequency is proposed to overcome the lack on the information given by the homodyne system.

  1. Testing the unified model of AGN with broadband polarimetry

    Science.gov (United States)

    Marin, F.

    2015-09-01

    The keystone of the unified model of AGN is the detection of optical broad line signatures in the polarized spectra of Seyfert-2s. Perpendicular scattering of BLR photons in the polar regions towards our line-of-sight naturally explains the anisotropic nature of AGN, likely to be due to equatorial obscuration. Hence, the observed AGN properties differ according to the orientation of the nuclear structure. However, the inclination of the system is not easily derived directly from observations, resulting in loose constraints, especially if estimated only from spectroscopic measurements. In this presentation, I will highlight the importance of polarimetric simulations in determining the true orientation of AGN by showing different realizations of the unified model. Predictions will be compared to a substantial catalog of optical-UV observations and extended towards the X-ray regime. The pre-selection by the ESA of a X-ray polarimeter for the study phase of the next M4 mission is a step forward in a better, broadband, understanding of AGN.

  2. Advanced Broadband Links for TIER III UAV Data Communication

    Science.gov (United States)

    Griethe, Wolfgang; Gregory, Mark; Heine, Frank; Kampfner, Hartmut

    2011-08-01

    Unmanned Aeronautical Vehicle (UAV) are getting more and more importance because of their prominent role as national reconnaissance systems, for disaster monitoring, and environmental mapping. However, the existence of reliable and robust data links are indispensable for Unmanned Aircraft System (UAS) missions. In particular for Beyond Line-Of-Sight operations (BLOS) of Tier III UAVs, satellite data links are a key element since extensive sensor data have to be transmitted preferably in real-time or near real-time.The paper demonstrates that the continuously increasing number of UAS and the intensified use of high resolution sensors will reveal RF-bandwidth as a limitating factor in the communication chain of Tier III UAVs. The RF-bandwidth gap can be partly closed by use of high-order modulation, of course, but much more progress in terms of bandwidth allocation can be achieved by using optical transmission technology. Consequently, the paper underlines that meanwhile this technology has been sufficiently verified in space, and shows that optical links are suited as well for broadband communications of Tier III UAVs. Moreover, the advantages of LaserCom in UAV scenarios and its importance for Network Centric Warfare (NCW) as well as for Command, Control, Communications, Computers, Intelligens, Surveillance, and Reconnaissance (C4ISR) are emphasized. Numerous practical topics and design requirements, relevant for the establishment of optical links onboard of Tier III UAVs, are discussed.

  3. Broadband Asymmetric Light Transmission at Metal/Dielectric Composite Grating.

    Science.gov (United States)

    Zhu, Rui; Wu, Xuannan; Hou, Yidong; Zheng, Gaige; Zhu, Jianhua; Gao, Fuhua

    2018-01-17

    Optical diode-like effect has sparked growing interest in recent years due to its potential applications in integrated photonic systems. In this paper, we propose and numerically demonstrate a new type of easy-processing metal/dielectric cylinder composite grating on semi-sphere substrate, which can achieve high-contrast asymmetric transmission of unpolarized light for the sum of all diffraction modes in the entire visible region, and effectively guide the diffraction light transmitting out the substrate. The asymmetric light transmission (ALT) ratio is larger than 2 dB in the waveband from 380 nm to 780 nm and the maximum ALT ratio can reach to 13 dB at specified wavelengths. The thorough theoretical research reveals that the proposed metal/dielectric pillar composite grating structure, together with the substrate, can effectively excite localized surface plasmonic resonance (LSPR) effect and waveguide mode (WGM), and enlarge the diffraction difference between forward and backward transmission spaces, including both number of diffraction orders and diffraction efficiency, thus resulting in high-contrast broadband ALT phenomenon. In particular, lowering the symmetry of the grating can achieve polarization-dependent ALT. Such a type of easy-processing ALT device with high performance for both polarized and unpolarized light can be regarded as suitable candidates in practical applications.

  4. Optimization of filtering schemes for broadband astro-combs.

    Science.gov (United States)

    Chang, Guoqing; Li, Chih-Hao; Phillips, David F; Szentgyorgyi, Andrew; Walsworth, Ronald L; Kärtner, Franz X

    2012-10-22

    To realize a broadband, large-line-spacing astro-comb, suitable for wavelength calibration of astrophysical spectrographs, from a narrowband, femtosecond laser frequency comb ("source-comb"), one must integrate the source-comb with three additional components: (1) one or more filter cavities to multiply the source-comb's repetition rate and thus line spacing; (2) power amplifiers to boost the power of pulses from the filtered comb; and (3) highly nonlinear optical fiber to spectrally broaden the filtered and amplified narrowband frequency comb. In this paper we analyze the interplay of Fabry-Perot (FP) filter cavities with power amplifiers and nonlinear broadening fiber in the design of astro-combs optimized for radial-velocity (RV) calibration accuracy. We present analytic and numeric models and use them to evaluate a variety of FP filtering schemes (labeled as identical, co-prime, fraction-prime, and conjugate cavities), coupled to chirped-pulse amplification (CPA). We find that even a small nonlinear phase can reduce suppression of filtered comb lines, and increase RV error for spectrograph calibration. In general, filtering with two cavities prior to the CPA fiber amplifier outperforms an amplifier placed between the two cavities. In particular, filtering with conjugate cavities is able to provide 300 nm wavelength coverage. Such superior performance will facilitate the search for and characterization of Earth-like exoplanets, which requires <10 cm/s RV calibration error.

  5. Black phosphorus: broadband nonlinear optical absorption and application

    Science.gov (United States)

    Li, Ying; He, Yanliang; Cai, Yao; Chen, Shuqing; Liu, Jun; Chen, Yu; Yuanjiang, Xiang

    2018-02-01

    Black phosphorus (BP), 2D layered material with layered dependent direct bandgap (0.3 eV (bulk), 2.0 eV (single layer)) that has gained renewed attention, has been demonstrated as an extremely appropriate optical material for broadband optical applications from infrared to mid-infrared wavebands. Herein, by coupling multi-layer BP films with microfiber, we fabricated a nonlinear optical device with long light–matter interaction distance and enhanced damage threshold. Through taking full advantage of its fine nonlinear optical absorption property, we obtained stable mode-locking (51 ps) and Q-switched mode-locking states in Yb-doped or Er-doped (403.7 fs) all-fiber lasers and the single-longitudinal-mode operation (53 kHz) in an Er-doped fiber laser with enhanced power tolerance, using the same nonlinear optical device. Our results showed that BP could be a favorable nonlinear optical material for developing BP-enabled wave-guiding photonic devices, and revealed new insight into BP for high optical power unexplored optical devices.

  6. 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.

  7. Tunable Broadband Transparency of Macroscopic Quantum Superconducting Metamaterials

    Directory of Open Access Journals (Sweden)

    Daimeng Zhang

    2015-12-01

    Full Text Available Narrow-band invisibility in an otherwise opaque medium has been achieved by electromagnetically induced transparency (EIT in atomic systems. The quantum EIT behavior can be classically mimicked by specially engineered metamaterials via carefully controlled interference with a “dark mode.” However, the narrow transparency window limits the potential applications that require a tunable wideband transparent performance. Here, we present a macroscopic quantum superconducting metamaterial with manipulative self-induced broadband transparency due to a qualitatively novel nonlinear mechanism that is different from conventional EIT or its classical analogs. A near-complete disappearance of resonant absorption under a range of applied rf flux is observed experimentally and explained theoretically. The transparency comes from the intrinsic bistability of the meta-atoms and can be tuned on and off easily by altering rf and dc magnetic fields, temperature, and history. Hysteretic in situ 100% tunability of transparency paves the way for autocloaking metamaterials, intensity-dependent filters, and fast-tunable power limiters.

  8. 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

    2016-09-12

    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.

  9. A broadband ultrathin metamaterial absorber using tilted parallel strips

    Science.gov (United States)

    Ahmadi, Farzad; Ida, Nathan

    2017-02-01

    A polarization insensitive metamaterial absorber is proposed consisting of a dielectric layer sandwiched between two tilted parallel metallic strips and a ground plane. First, a new analytical model is introduced to predict the resonance frequency for square, rectangular and wire geometries which shows less relative errors in comparison with previously proposed models. Then, ultra wide bandwidth absorption covering the entire x-band and Ku-band restricting a 10-dB absorption bandwidth is achieved with a relative material thickness λ0/10 and a relative FWHM absorption bandwidth of 90% for normal incidence angle. The model also shows good absorption coefficients for oblique incident angles for both s- and p-polarizations. Three different resonance modes are observed, which led to such broadband absorption. Each resonance mode is investigated to determine its dependence on the scatterers and unit cell dimensions, which can help one to design a multiple band absorber. The electromagnetic field distributions of the scatterers are studied to explain the absorber mechanism. The results are compared to previous works showing remarkable improvement.

  10. Reverberation Mapping Quasars: X-ray and broadband SED properties

    Science.gov (United States)

    Merloni, A.; Simm, T.; Nandra, K.; Green, P.

    2017-10-01

    An ongoing SDSS reverberation mapping (RM) program (Shen et al. 2015) provides significantly improved black hole mass estimates for a large sample of QSOs out to redshift ˜3 in a single 7 square degree field. A recently approved large XMM-Newton program will complete the X-ray coverage of the field, contributing to a unique legacy sample of hundreds of QSOs with accurately measured bolometric luminosity, spectral energy distributions, Eddington ratios and variability properties. As illustration, we present here the X-ray spectral properties of the RM-QSOs derived from the analysis of all existing XMM-Newton and deep Chandra (AEGIS field) observations of the field. Taking advantage of the unprecedented multi-band, multi-epoch imaging and spectroscopy provided by the SDSS-RM campaign, the Pan-STARRS1 medium deep survey and the GALEX time domain survey we study in detail their instantaneous broadband spectral energy distributions to obtain accurate measures of the bolometric luminosity and to test accretion disk models. This data set allows us to dissect correlations between optical/X-ray spectral properties with black hole mass and Eddington ratio, as well as to constrain evolution of the radiative efficiency providing a first handle on black hole spin evolution in a large, statistical sample of AGN.

  11. Broadband mid-infrared superlattice light-emitting diodes

    Science.gov (United States)

    Ricker, R. J.; Provence, S. R.; Norton, D. T.; Boggess, T. F.; Prineas, J. P.

    2017-05-01

    InAs/GaSb type-II superlattice light-emitting diodes were fabricated to form a device that provides emission over the entire 3-5 μm mid-infrared transmission window. Variable bandgap emission regions were coupled together using tunnel junctions to emit at peak wavelengths of 3.3 μm, 3.5 μm, 3.7 μm, 3.9 μm, 4.1 μm, 4.4 μm, 4.7 μm, and 5.0 μm. Cascading the structure recycles the electrons in each emission region to emit several wavelengths simultaneously. At high current densities, the light-emitting diode spectra broadened into a continuous, broadband spectrum that covered the entire mid-infrared band. When cooled to 77 K, radiances of over 1 W/cm2 sr were achieved, demonstrating apparent temperatures above 1000 K over the 3-5 μm band. InAs/GaSb type-II superlattices are capable of emitting from 3 μm to 30 μm, and the device design can be expanded to include longer emission wavelengths.

  12. 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.

  13. 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.

  14. 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).

  15. 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.

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

    Science.gov (United States)

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

    2012-12-01

    Seismic surveying is the most important type of deep exploration and oil-gas exploration. In order to obtain the high-quality deeper strata information in the deep exploration, large amount of drugs, large group interval and the low-frequency detector must be used, the length of the measuring line is usually tens of kilometers or even hundreds of kilometers. Conventional seismic exploration instrument generally do not have site storage function or limited storage capacity, due to the shackles of the transmission cable, the system bulky and difficult to handle, inefficient construction, high labor costs, collection capabilities and accuracy are the drawbacks of restrictions. This article describes a deep exploration of high-performance broadband seismograph. To ensure the quality of data acquisition, the 24-bit ADCs applied and the low noise analog front end circuit designed carefully, which enable the instrument noise level less than 1.5uV and the dynamic range over 120dB. Integrate dual-frequency GPS OEM board with the acquisition station. As a result, the acquisition station itself can make a static self-positioning and the horizontal accuracy can reach to centimeter-level. Furthermore, it can provide high accuracy position data to subsequent seismic data processing. Combine the precise timing system of GPS with digital clock that has high precision oven-controlled crystal oscillator (OCXO). It enables the accuracy of clock synchronization to reach 0.01ms and the stability of OCXO frequency reach 3e-8, which could solve the problems of synchronous triggering of the data acquisition unit of multiple recording units in the instrument and real-time calibration of the inaccuracy of system clock. The instrument uses a high-capacity (large than 16GB/station), high reliability of the seismic data storage solutions, which enables the instrument to record continuously for more than 138 hours at the sampling rate of 2000sps. Using low-power design techniques for power

  17. Topology optimization of anisotropic broadband double-negative elastic metamaterials

    Science.gov (United States)

    Dong, Hao-Wen; Zhao, Sheng-Dong; Wang, Yue-Sheng; Zhang, Chuanzeng

    2017-08-01

    As the counterpart of electromagnetic and acoustic metamaterials, elastic metamaterials are artificial periodic elastic composite materials offering the possibility to manipulate elastic wave propagation in the subwavelength scale through different mechanisms. For the promising superlensing in the medical ultrasonic detection, double-negative metamaterials possessing the negative effective mass density and elastic modulus simultaneously can be utilized as the ideal superlens for breaking the diffraction limit. In this paper, we present a topology optimization scheme to design the two-dimensional (2D) single-phase anisotropic elastic metamaterials with broadband double-negative effective material properties and demonstrate the superlensing effect at the deep-subwavelength scale. We also discuss the impact of several design parameters adopted in the objective function and constraints on the optimized results. Unlike all previously reported mechanisms, the present optimized structures exhibit the novel quadrupolar or multipolar resonances for the negative effective mass density and negative effective elastic modulus. In addition, negative refraction of the transverse waves in a single-phase material is observed. Most optimized structures in this paper can serve as the anisotropic zero-index metamaterials for the longitudinal or transverse waves at a certain frequency. The cloaking effect is demonstrated for both the longitudinal and transverse waves. Moreover, with the particular constraints in the optimization procedure, a super-anisotropic metamaterial exhibiting the double-negative and hyperbolic dispersions in two principal directions within two different frequency ranges is obtained. The developed optimization scheme provides a robust computational tool for negative-index engineering of elastic metamaterials and may guide the design and optimization of other types of metamaterials, including the electromagnetic and acoustic metamaterials. The unusual properties

  18. 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

  19. 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.

  20. Multicore fiber beamforming network for broadband satellite communications

    Science.gov (United States)

    Zainullin, Airat; Vidal, Borja; Macho, Andres; Llorente, Roberto

    2017-02-01

    Multi-core fiber (MCF) has been one of the main innovations in fiber optics in the last decade. Reported work on MCF has been focused on increasing the transmission capacity of optical communication links by exploiting space-division multiplexing. Additionally, MCF presents a strong potential in optical beamforming networks. The use of MCF can increase the compactness of the broadband antenna array controller. This is of utmost importance in platforms where size and weight are critical parameters such as communications satellites and airplanes. Here, an optical beamforming architecture that exploits the space-division capacity of MCF to implement compact optical beamforming networks is proposed, being a new application field for MCF. The experimental demonstration of this system using a 4-core MCF that controls a four-element antenna array is reported. An analysis of the impact of MCF on the performance of antenna arrays is presented. The analysis indicates that the main limitation comes from the relatively high insertion loss in the MCF fan-in and fan-out devices, which leads to angle dependent losses which can be mitigated by using fixed optical attenuators or a photonic lantern to reduce MCF insertion loss. The crosstalk requirements are also experimentally evaluated for the proposed MCF-based architecture. The potential signal impairment in the beamforming network is analytically evaluated, being of special importance when MCF with a large number of cores is considered. Finally, the optimization of the proposed MCF-based beamforming network is addressed targeting the scalability to large arrays.

  1. 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.

  2. A Low Frequency Broadband Flextensional Ultrasonic Transducer Array.

    Science.gov (United States)

    Savoia, Alessandro Stuart; Mauti, Barbara; Caliano, Giosuè

    2016-01-01

    In this paper, we propose the design and the fabrication of a multicell, piezoelectrically actuated, flextensional transducer array structure, characterized by a low mechanical impedance, thus allowing wideband and high-sensitivity immersion operation in the low ultrasonic frequency range. The transducer structure, consisting of a plurality of circular elementary cells orderly arranged according to a periodic hexagonal tiling, features a high flexibility in the definition of the active area shape and size. We investigate, by finite element modeling (FEM), the influence of different piezoelectric and elastic materials for the flexural plate, for the plate support and for the backing, on the transducer electroacoustic behavior. We carry out the dimensioning of the transducer components and cell layout, in terms of materials and geometry, respectively, by aiming at a circular active area of 80-mm diameter and broadband operation in the 30-100-kHz frequency range in immersion. PZT-5H ceramic disks and a calibrated thickness stainless steel plate are chosen for the vibrating structure, and FR-4 laminates and a brass plate, respectively, for the plate support and the backing. The diameter of the individual cells is set to 6 mm resulting in 121 cells describing a quasi-circular area, and the total thickness of the transducer is less than 10 mm. We report on the fabrication process flow for the accurate assembly of the transducer, based, respectively, on epoxy resin and wire bonding for the mechanical and electrical interconnection of the individual parts. The results of the electrical impedance and transmit pressure field characterization are finally reported and discussed.

  3. A disorder-based strategy for tunable, broadband wave attenuation

    Science.gov (United States)

    Zhang, Weiting; Celli, Paolo; Cardella, Davide; Gonella, Stefano

    2017-04-01

    One of the most daunting limitations of phononic crystals and acoustic/elastic metamaterials is their passivity: a given configuration is bound to display its phononic properties only around its design point, i.e., working at some pre-determined operating conditions. In the past decade, this shortcoming has inspired the design of phononic media with tunable wave characteristics; noteworthy results have been obtained through a family of methodologies involving shunted piezoelectric elements. Shunting a piezoelectric element means connecting it to a passive electric circuit; tunability stems from the ability to modify the effective mechanical properties of the piezoelectric medium by modifying the circuit characteristics. One of the most popular shunting circuits is the resistor-inductor, which allows the patch-and-shunt system to behave as an electromechanical resonator. A common motif among the works employing shunted piezos for phononic control is periodicity: the patches are typically periodically placed in the domain and the circuits are identically tuned. The objective of this work is to demonstrate that the wave attenuation performance of structures with shunted piezoelectric patches can be improved by leveraging notions of organized disorder. Based on the idea of rainbow trapping broadband wave attenuation obtained by tuning an array of resonators at distinct neighboring frequencies we design and test an electromechanical waveguide structure capable of attenuating waves over broad frequency ranges. In order to emphasize the fact that periodicity is not a binding requirement when working with RL shunts (which induce locally resonant bandgaps), we report on the performance of random arrangements of patches. In an attempt to demonstrate the tunability attribute of our strategy, we take advantage of the reconfigurability of the circuits to show how a single waveguide can attenuate both waves and vibrations over different frequency ranges.

  4. 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...

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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

  12. A Broadband Silicon Seismic Package for Planetary Exploration

    Science.gov (United States)

    Pike, W. Thomas; Standley, Ian; Calcutt, Simon; Kedar, Sharon

    2017-04-01

    The Silicon Seismic Package (SSP) is a compact, 0.3 ng/rtHz sensitivity silicon microseismometer based on the hardware successfully delivered to the InSight Mars 2018 mission. The SSP provides a sensitivity and dynamic range comparable to significantly more massive broadband terrestrial instruments in a robust, compact package. Combined with a high resolution radiation-hardened digitiser under development, the SSP offers high performance seismic monitoring under a range of planetary environments. The sensor is micromachined from single-crystal silicon by through-wafer deep reactive-ion etching to produce a non-magnetic suspension and proof mass. It is robust to high shock (> 1000 g) and vibration (> 30 grms). For qualification SP units have undergone the full thermal cycles of the InSight mission and has been noise tested down to 208K and up to 330K, with no degradation in the performance in both cases. In addition, the sensor has been tested as functional down to 77K. The total mass for the three-axis SP delivery is 635g while the power requirement is less than 400 mW. The SSP has particular advantages for a planetary deployment. All three axes deliver full performance over a tilt range of ±1 m/s2 which allows for operation without levelling. With no magnetic sensitivity and a temperature sensitivity below 2E-5 m/s^2, there is no need for magnetic field monitoring and the additional resources for thermal isolation are also much reduced. In terms of performance the SSP has fast initialisation, reaching a noise floor below 1 ng/√Hz in less than a minute from an untilted configuration. The noise floor is 0.3 ng/rtHz from 10 s to 10 Hz, with a long period noise below 10 ng/rtHz at 1000s. This allows tidal measurements as well as seismic monitoring for a number of proposed planetary missions.

  13. Characteristics of Broadband Seismic Noise in Taiwan and Neighboring Islands

    Science.gov (United States)

    Chen, Ching-Wei; Rau, Ruey-Juin

    2017-04-01

    We used seismic waveform data from 115 broad-band stations of BATS (Institute of Earth Science, Academia Sinica) and Central Weather Bureau Seismic Network from 2012 to 2016 for noise-level mapping in Taiwan and neighboring islands. We computed Power Spectral Density (PSD) for each station and analyzed long-term variance of microseism energy and polarizations of noise for severe weather events. The island of Taiwan is surrounded by ocean and the Central Range which has the highest peak Jade Mountain at 3,952 meters height occupies more than 66% of the island and departs it into the east and west coasts. The geographic settings then result in the high population density in the western plain and northern Taiwan. The dominant noise source in the microseism band (periods from 4-20 seconds) is the coupling between the near-coast ocean and sea floor which produces the high noise of averaging -130 dB along the west coastal area. In the eastern volcanic-arc coastal areas, the noise level is about 7% smaller than the west coast due to its deeper offshore water depth. As for the shorter periods (0.1-0.25 seconds) band, the so-called culture noise, an anthropic activity variance with the highest -103 dB can be identified in the metropolitan areas, such as the Taipei city and the noise level in the Central Range area is averaging -138 dB. Moreover, the noise also shows a daily and temporal evolution mainly related to the traffic effect. Furthermore, we determined the noise level for the entire island of Taiwan during 26-28 September, 2016, when the typhoon Megi hit the island and retrieved the enhancement of secondary microseism energy for each stations. Typhoon Megi landed in eastern and central Taiwan and reached the maximum wind speed of 45m/s in the surrounded eyewall. The Central Range, as a barrier, decreased the wind speed in southern Taiwan making an enhancement less than 10 dB, while in northern Taiwan where the direction the typhoon headed to, can reach more than 35

  14. The unsustainable directionality of innovation – The example of the broadband transition

    DEFF Research Database (Denmark)

    Røpke, Inge

    2012-01-01

    Information and communication technology (ICT) can be seen as a general-purpose technology with wide-ranging socio-economic and environmental implications across sectors. ICTs also constitute a system of technologies with stronger internal links since the emergence of the Internet and broadband...... as a new information infrastructure. The new infrastructure has co-evolved with widespread integration of ICTs in everyday life, and consumer demand has been decisive for ICT innovation. This article explores the environmental directionality of ICT innovation and the broadband transition, focusing mainly...... more prominently in the broadband transition. Finally, it is discussed how the direction of ICT innovation could be influenced in order to realize more of the positive sustainability potential....

  15. Ultra-broadband strong light absorption based on thin multilayered metamaterials

    CERN Document Server

    Ding, Fei; Cheng, Hao; Mo, Lei; He, Sailing

    2013-01-01

    Light absorption plays an important role in many research areas. Here, we propose and demonstrate a thin ultra-broadband strong light absorber consisting of periodic taper arrays constructed by an alumina-chrome multilayered metamaterial (MM) on a gold substrate. The large material loss of chrome and special anisotropic effective permittivity of the MM are the fundamental origins of the ultra-broadband absorption in which no resonance is used. The absorber is lowly sensitive to the incident angle, and can be insensitive to the polarization. One two-dimensional periodic array of 400nm-height MM tapers is fabricated. The measured absorption can be over 90% almost over the entire solar spectrum, reaching an average level of 96%, and it remains high (above 85%) even in the longer wavelength range until 4um. The proposed absorbers open a new avenue to realize broadband thin light-harvesting structures.

  16. 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...

  17. Viewpoint: Telecommunications and Internet Broadband Policy: Sorting Out the Pieces for Telerehabilitation

    Directory of Open Access Journals (Sweden)

    Kate D. Seelman

    2010-09-01

    Full Text Available Technological change is accelerating and with it regulatory upheaval.  Most of us agree that providing universal telecommunication services to all our citizens is a worthy ideal.  Nonetheless, many of us do not agree that regulation should be the means to make broadband Internet services widely available. This Viewpoint begins sorting out pieces of the emerging United States, regulatory and policy puzzle for broadband Internet with an eye to the interests of telerehabilitation providers and consumers. Just how might changes in legal authority, regulation and agency jurisdictions impact us?Key words: telecommunications regulation, telerehabilitation, Federal Communications Commission (FCC, Telecommunications Act of 1996, National Broadband Plan; Comcast vs. FCC; electronic health records (EHR; personal health records (PHR; health information technology (HIT, 

  18. Ultrafast broadband Fourier-transform CARS spectroscopy operating at 50,000 spectra/second

    Science.gov (United States)

    Tamamitsu, Miu; Sakaki, Yusuke; Nakamura, Tasuku; Podagatlapalli, G. Krishna; Ideguchi, Takuro; Goda, Keisuke

    2017-02-01

    We present a coherent Raman scattering (CRS) spectroscopy technique achieving a CRS spectral acquisition rate of 50,000 spectra/second over a Raman spectral region of 200 - 1430 cm-1 with a resolution of 4.2 cm-1. This ultrafast, broadband and high-resolution CRS spectroscopic performance is realized by a polygonal Fourier-domain delay line serving as an ultra-rapid optical-path-length scanner in a broadband Fourier-transform coherent anti-Stokes Raman scattering (CARS) spectroscopy platform. We present a theoretical description of the technique and demonstrate continuous, ultrafast, broadband, and high-resolution CARS spectroscopy on a liquid toluene sample using our proof-of-concept setup.

  19. Broadband characteristics of vibration energy harvesting using one-dimensional phononic piezoelectric cantilever beams

    Energy Technology Data Exchange (ETDEWEB)

    Chen Zhongsheng, E-mail: czs_study@sina.com [Key Laboratory of Science and Technology on Integrated Logistics Support, College of Mechatronic Engineering and Automation, National University of Defense Technology, Changsha, Hunan 410073 (China); Yang Yongmin; Lu Zhimiao; Luo Yanting [Key Laboratory of Science and Technology on Integrated Logistics Support, College of Mechatronic Engineering and Automation, National University of Defense Technology, Changsha, Hunan 410073 (China)

    2013-02-01

    Nowadays broadband vibration energy harvesting using piezoelectric effect has become a research hotspot. The innovation in this paper is the widening of the resonant bandwidth of a piezoelectric harvester based on phononic band gaps, which is called one-dimensional phononic piezoelectric cantilever beams (PPCBs). Broadband characteristics of one-dimensional PPCBs are analyzed deeply and the vibration band gap can be calculated. The effects of different parameters on the vibration band gap are presented by both numerical and finite element simulations. Finally experimental tests are conducted to validate the proposed method. It can be concluded that it is feasible to use the PPCB for broadband vibration energy harvesting and there should be a compromise among related parameters for low-frequency vibrations.

  20. Broadband Metamaterial Reflectors for Polarization Manipulation Based on Cross/Ring Resonators

    Directory of Open Access Journals (Sweden)

    Z. Zhang

    2016-09-01

    Full Text Available We presented the investigation of broadband metamaterial reflector for polarization manipulation based on cross/ring resonators. It is demonstrated that the meta¬material reflector can convert the linearly polarized inci¬dent wave to its cross polarized wave or circularly polar¬ized wave. Due to the multiple resonances at neighboring frequencies, the proposed reflector presents broadband property and high efficiency. The measured fraction band¬width of cross polarization conversion is 55.5% with effi¬ciency higher than 80%. Furthermore, a broadband circu¬lar polarizer is designed by adjusting the dimension para¬meters and the measured fraction bandwidth exceeds 30%.

  1. An application of the TODIM method to the evaluation of Broadband Internet plans

    Directory of Open Access Journals (Sweden)

    Luís Alberto Duncan Rangel

    2011-08-01

    Full Text Available This article presents a case study of the evaluation of the various types of access to the Broadband Internet available to a small company, located in Volta Redonda, in the state of Rio de Janeiro. This small company needs to implement Broadband Internet in its establishment and sought an evaluation of the companies which work providing this type of service. With the aim of carrying out a technical evaluation of the provision of the Broadband Internet service and, considering the diverse points of view and needs of this small company, a Multicriteria Decision Aiding Method, the TODIM method, was used. By means of this research, the power of this Operational Research tool was verified in the search for the solution to the problem of ranking the services offered in the city, according to the criteria chosen by this small company.

  2. All-dielectric resonant cavity-enabled metals with broadband optical transparency

    Science.gov (United States)

    Liu, Zhengqi; Zhang, Houjiao; Liu, Xiaoshan; Pan, Pingping; Liu, Yi; Tang, Li; Liu, Guiqiang

    2017-06-01

    Metal films with broadband optical transparency are desirable in many optoelectronic devices, such as displays, smart windows, light-emitting diodes and infrared detectors. As bare metal is opaque to light, this issue of transparency attracts great scientific interest. In this work, we proposed and demonstrated a feasible and universal approach for achieving broadband optical transparent (BOT) metals by utilizing all-dielectric resonant cavities. Resonant dielectrics provide optical cavity modes and couple strongly with the surface plasmons of the metal film, and therefore produce a broadband near-unity optical transparent window. The relative enhancement factor (EF) of light transmission exceeds 3400% in comparison with that of pure metal film. Moreover, the transparent metal motif can be realized by other common metals including gold (Au), silver (Ag) and copper (Cu). These optical features together with the fully retained electric and mechanical properties of a natural metal suggest that it will have wide applications in optoelectronic devices.

  3. Anechoic wind tunnel study of turbulence effects on wind turbine broadband noise

    Science.gov (United States)

    Loyd, B.; Harris, W. L.

    1995-01-01

    This paper describes recent results obtained at MIT on the experimental and theoretical modelling of aerodynamic broadband noise generated by a downwind rotor horizontal axis wind turbine. The aerodynamic broadband noise generated by the wind turbine rotor is attributed to the interaction of ingested turbulence with the rotor blades. The turbulence was generated in the MIT anechoic wind tunnel facility with the aid of biplanar grids of various sizes. The spectra and the intensity of the aerodynamic broadband noise have been studied as a function of parameters which characterize the turbulence and of wind turbine performance parameters. Specifically, the longitudinal integral scale of turbulence, the size scale of turbulence, the number of turbine blades, and free stream velocity were varied. Simultaneous measurements of acoustic and turbulence signals were made. The sound pressure level was found to vary directly with the integral scale of the ingested turbulence but not with its intensity level. A theoretical model based on unsteady aerodynamics is proposed.

  4. A New Broadband Microwave Frequency Device for Powering ECR Ion Sources

    CERN Document Server

    Kawai, Yoko; Liu, Yuan

    2005-01-01

    The multiple discrete frequency technique has been used to improve the performance of conventional B-field configuration ECR ion sources. However, the practical application of this technique is very costly, requiring multiple independent single-frequency rf power supplies and complicated rf injection systems. Broadband sources of rf power offer a low-cost and more effective method for increasing the physical size of the ECR zone within these ion sources. An Additive White Gaussian Noise Generator (AWGNG) system for injecting broadband rf power into these ion sources has been developed in conjunction with a commercial firm. The noise generator, in combination with an external oscillator and a traveling wave tube amplifier, can be used to generate broadband rf power without modifying the injection system. The AWGNG and its use for enhancing the performance of conventional B-field configuration ECR ion sources will be described.

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

    Science.gov (United States)

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

    2016-07-01

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

  6. Broadband light absorber based on porous alumina structure covered with ultrathin iridium film

    Science.gov (United States)

    Fang, Bo; Yang, Chenying; Pang, Chenlei; Shen, Weidong; Zhang, Xing; Zhang, Yueguang; Yuan, Wenjia; Liu, Xu

    2017-04-01

    In this letter, we propose a broadband absorber with high efficiency by an atomic layer depositing nanometer iridium (Ir) film onto a porous anodic alumina (PAA) template. The average absorption is able to achieve as high as 93.4% from 400 to 1100 nm and the absorption efficiency can reach up to 96.8% for the improved structure of the quadrangular frustum pyramid array. Not only the hexagonal latticed structures of the PAA template but also many similar structures based on gratings or holes with the square latticed or other latticed mode can realize the broadband high absorption efficiency. The light absorbed within the Ir/Glass interface and the sidewalls of PAA by the light funneling effect both contribute to the broadband absorption with high efficiency. This absorber, described in this paper, can be manufactured with a low-cost and large-area manner and has potential applications in fields of light harvesting, imaging, etc.

  7. 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.

  8. On the Scaling Law for Broadband Shock Noise Intensity in Supersonic Jets

    Science.gov (United States)

    Kanudula, Max

    2009-01-01

    A theoretical model for the scaling of broadband shock noise intensity in supersonic jets was formulated on the basis of linear shock-shear wave interaction. An hypothesis has been postulated that the peak angle of incidence (closer to the critical angle) for the shear wave primarily governs the generation of sound in the interaction process rather than the noise generation contribution from off-peak incident angles. The proposed theory satisfactorily explains the well-known scaling law for the broadband shock -associated noise in supersonic jets.

  9. Broadband vibration energy harvester utilizing three out-of-plane modes of one vibrating body

    Science.gov (United States)

    Park, Shi-Baek; Jang, Seon-Jun; Kim, In-Ho; Choi, Yong Je

    2017-10-01

    In this paper, we introduce the concept, design equation, and realization of a broadband electromagnetic vibrational energy harvester. The spatial vibrating system in the proposed harvester is arranged to have three out-of-plane vibration modes. We devise the design method for its three natural frequencies and accompanying modes and apply it to the broadband energy harvesting by locating three frequencies close to each other. The numerical simulation and the experimental results show that it satisfies the designated frequencies as well as the enhanced bandwidth for power generation.

  10. Telecommunications and internet broadband policy: sorting out the pieces for telerehabilitation.

    Science.gov (United States)

    Seelman, Katherine D

    2010-01-01

    Technological change is accelerating and with it regulatory upheaval. Most of us agree that providing universal telecommunication services to all our citizens is a worthy ideal. Nonetheless, many of us do not agree that regulation should be the means to make broadband Internet services widely available. This Viewpoint begins sorting out pieces of the emerging United States, regulatory and policy puzzle for broadband Internet with an eye to the interests of telerehabilitation providers and consumers. Just how might changes in legal authority, regulation and agency jurisdictions impact us?

  11. Numerical Simulation of Partially-Coherent Broadband Optical Imaging Using the FDTD Method

    Science.gov (United States)

    Çapoğlu, İlker R.; White, Craig A.; Rogers, Jeremy D.; Subramanian, Hariharan; Taflove, Allen; Backman, Vadim

    2012-01-01

    Rigorous numerical modeling of optical systems has attracted interest in diverse research areas ranging from biophotonics to photolithography. We report the full-vector electromagnetic numerical simulation of a broadband optical imaging system with partially-coherent and unpolarized illumination. The scattering of light from the sample is calculated using the finite-difference time-domain (FDTD) numerical method. Geometrical optics principles are applied to the scattered light to obtain the intensity distribution at the image plane. Multilayered object spaces are also supported by our algorithm. For the first time, numerical FDTD calculations are directly compared to and shown to agree well with broadband experimental microscopy results. PMID:21540939

  12. BROADBAND METHOD FOR GROUP VELOCITY DISPERSION MEASUREMENTS IN THE MID-INFRARED

    Directory of Open Access Journals (Sweden)

    D. S. Klimentov

    2011-01-01

    Full Text Available A setup for broadband measurements of dispersion parameter in optical fibers based on the Mach–Zehnder interferometer is developed. Tm-doped fiber pumped at 1.61 μm was used as a source of broadband emission, that allowed to achieve the measurement spectral range of 1700 to 2000 nm. The method is applicable for comparatively short pieces of optical fiber with lengths of less than 1 meter. The method was successfully tested for the standard telecommunication SMF-28 fiber.

  13. Metamaterial Composite with an Ultra-Broadband Usable Range of over 25 Terahertz

    DEFF Research Database (Denmark)

    Strikwerda, Andrew; Zalkovskij, Maksim; Krabbe, Alexander

    2014-01-01

    Using a metamaterial composite , we demonstrate a band pass filter that has only a single transmission mode from 0 to >25 THz. This usable bandwidth match es , or e xceed s , that of current ly used THz sources and demonstrates a path towards broadband metamaterial design.......Using a metamaterial composite , we demonstrate a band pass filter that has only a single transmission mode from 0 to >25 THz. This usable bandwidth match es , or e xceed s , that of current ly used THz sources and demonstrates a path towards broadband metamaterial design....

  14. High broad-band photoresponsivity of mechanically formed InSe-graphene van der Waals heterostructures.

    Science.gov (United States)

    Mudd, Garry W; Svatek, Simon A; Hague, Lee; Makarovsky, Oleg; Kudrynskyi, Zakhar R; Mellor, Christopher J; Beton, Peter H; Eaves, Laurence; Novoselov, Kostya S; Kovalyuk, Zakhar D; Vdovin, Evgeny E; Marsden, Alex J; Wilson, Neil R; Patanè, Amalia

    2015-07-01

    High broad-band photoresponsivity of mechanically formed InSe-graphene van der Waals heterostructures is achieved by exploiting the broad-band transparency of graphene, the direct bandgap of InSe, and the favorable band line up of InSe with graphene. The photoresponsivity exceeds that for other van der Waals heterostructures and the spectral response extends from the near-infrared to the visible spectrum. © 2015 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Combining Wired and Wireless Networks for a QoS-Aware Broadband Infrastructure

    DEFF Research Database (Denmark)

    Pedersen, Jens Myrup; Riaz, Muhammad Tahir; Knudsen, Thomas Phillip

    2004-01-01

    We show how integrated planning of wired and wireless infrastructures can be used to build a QoS-aware broadband infrastructure. The outset is a case study of the municipality of Hals, a rural community in Denmark, where the objective is to establish a broadband infrastructure reaching all...... To The Home for primary connections and Fixed Wireless Access for backup. This is implemented over 15 years, during which temporary solutions ensure sufficient QoS and reliability for all users. These temporary solutions form parts of the final solutions....

  16. III-V semiconductor resonators: A new strategy for broadband light perfect absorbers

    Science.gov (United States)

    Liu, Xiaoshan; Chen, Jian; Liu, Jiasong; Huang, Zhenping; Yu, Meidong; Pan, Pingping; Liu, Zhengqi

    2017-11-01

    Broadband light perfect absorbers (BPAs) are desirable for applications in numerous optoelectronics devices. In this work, a semiconductor-based broadband light perfect absorber (S-BPA) has been numerically demonstrated by utilizing plasmonlike resonances of high-index semiconductor resonators. A maximal absorption of 99.7% is observed in the near-infrared region. By taking the absorption above 80% into account, the spectral bandwidth reaches 340 nm. The absorption properties mainly originate from the optical cavity modes induced by the cylinder resonators and ultrathin semiconductor film. These optical properties and simple structural features can maintain the absorber platform with wide applications in semiconductor optoelectronics.

  17. Broadband and stable acoustic vortex emitter with multi-arm coiling slits

    KAUST Repository

    Jiang, Xue

    2016-05-16

    We present the analytical design and experimental realization of a scheme based on multi-arm coiling slits to generate the stable acoustic vortices in a broadband. The proposed structure is able to spiral the acoustic wave spatially and generate the twisted acoustic vortices with invariant topological charge for a long propagation distance. Compared with conventional methods which require the electronic control of a bulky loudspeaker, this scheme provides an effective and compact solution to generate acoustic vortices with controllable topological charge in the broadband, which offers more initiatives in the demanding applications.

  18. Photonic crystals with broadband, wide-angle, and polarization-insensitive transparency.

    Science.gov (United States)

    Yao, Zhongqi; Luo, Jie; Lai, Yun

    2016-11-01

    Photonic crystals (PhCs) are well-known band gap materials that can block the propagation of electromagnetic waves within certain frequency regimes. Here, we demonstrate that PhCs can also exhibit the contrary property: broadband, wide-angle, and polarization-insensitive transparency beyond normal dielectric solids. Such high transparency attributes to robust impedance matching between a large group of eigen-states in PhCs and propagating waves in free space. As a demonstration, a transparent wall for broadband microwaves is designed for enhancing the transmittance of WiFi and 4G signals.

  19. Room temperature Up-conversion detection of a broadband Mid-IR source

    DEFF Research Database (Denmark)

    Barh, Ajanta; Tidemand-Lichtenberg, Peter; Pedersen, Christian

    2016-01-01

    The paper presents efficient up-conversion based room temperature detection of a broadband mid-infrared light source, ranging from 3.6 ~ 4.9 μm, exploiting nonlinear sum frequency generation in a periodically poled lithium-niobate crystal.......The paper presents efficient up-conversion based room temperature detection of a broadband mid-infrared light source, ranging from 3.6 ~ 4.9 μm, exploiting nonlinear sum frequency generation in a periodically poled lithium-niobate crystal....

  20. Ultra-broadband Photonic Harmonic Mixer Based on Optical Comb Generation

    DEFF Research Database (Denmark)

    Zhao, Ying; Pang, Xiaodan; Deng, Lei

    2012-01-01

    We propose a novel photonic harmonic mixer operating at frequencies up to the millimeter-wave (MMW) band. By combining a broadband fiber-wireless signal with highorder harmonics of a fundamental local oscillator in an optical frequency comb generator, frequency down-conversion can be implemented...... without using costly ultra-broadband photodiode. It is theoretically shown that the down-conversion efficiency and the bandwidth of the mixer is highly dependent on the optical modulation indices and the fundamental frequency of comb lines. Down-conversion of a W-band (75-110GHz) fiberwireless signal...

  1. Characterization and calibration of ultraviolet broadband radiometers measuring erythemally weighted irradiance.

    Science.gov (United States)

    Hülsen, Gregor; Gröbner, Julian

    2007-08-10

    An ultraviolet calibration center has been established in Davos, Switzerland. It provides a laboratory for characterizing the spectral and angular response of broadband radiometers. The absolute calibration of these instruments is performed through the comparison to the reference spectroradiometer QASUME. We present what we believe to be a novel calibration methodology that explicitly includes the information of the angular and spectral response functions. From the results of the latest broadband intercomparison campaign, the typical uncertainties of these instruments could be obtained. Most radiometers have an expanded uncertainty of approximately 7%. The angular response introduces an uncertainty of 0.9%-7.2%, depending on the cosine error of the radiometer.

  2. A Broadband and High Gain Tapered Slot Antenna for W-Band Imaging Array Applications

    Directory of Open Access Journals (Sweden)

    Dong Sik Woo

    2014-01-01

    Full Text Available A broadband and high gain tapered slot antenna (TSA by utilizing a broadband microstrip- (MS- to-coplanar stripline (CPS balun has been developed for millimeter-wave imaging systems and sensors. This antenna exhibits ultrawideband performance for frequency ranges from 70 to over 110 GHz with the high antenna gain, low sidelobe levels, and narrow beamwidth. The validity of this antenna as imaging arrays is also demonstrated by analyzing mutual couplings and 4-element linear array. This antenna can be applied to mm-wave phased array, imaging array for plasma diagnostics applications.

  3. 77 FR 26987 - Connect America Fund; A National Broadband Plan for Our Future; Establishing Just and Reasonable...

    Science.gov (United States)

    2012-05-08

    ... Docket Nos. 01-92, 96-45; WT Docket No. 10-208; FCC 11-161] Connect America Fund; A National Broadband... collection associated with the Commission's Connect America Fund; A National Broadband Plan for Our Future... adopted a Report and Order, FCC 11-161, 76 FR 73830, November 29, 2011, Connect America Fund; A National...

  4. Perceived Benefits and Barriers to the Use of High-Speed Broadband in Ireland's Second-Level Schools

    Science.gov (United States)

    Coyne, Bryan; Devitt, Niamh; Lyons, Seán; McCoy, Selina

    2015-01-01

    As part of Ireland's National Digital Strategy, high-speed broadband is being rolled out to all second-level schools to support greater use of information and communication technology (ICT) in education. This programme signals a move from slow and unreliable broadband connections for many schools to a guaranteed high-speed connection with…

  5. Acoustic deterrence of bighead carp (Hypophthalmichthys nobilis) to a broadband sound stimulus

    Science.gov (United States)

    Vetter, Brooke J.; Murchy, Kelsie; Cupp, Aaron R.; Amberg, Jon J.; Gaikowski, Mark P.; Mensinger, Allen F.

    2017-01-01

    Recent studies have shown the potential of acoustic deterrents against invasive silver carp (Hypophthalmichthys molitrix). This study examined the phonotaxic response of the bighead carp (H. nobilis) to pure tones (500–2000 Hz) and playbacks of broadband sound from an underwater recording of a 100 hp outboard motor (0.06–10 kHz) in an outdoor concrete pond (10 × 5 × 1.2 m) at the U.S. Geological Survey Upper Midwest Environmental Science Center in La Crosse, WI. The number of consecutive times the fish reacted to sound from alternating locations at each end of the pond was assessed. Bighead carp were relatively indifferent to the pure tones with median consecutive responses ranging from 0 to 2 reactions away from the sound source. However, fish consistently exhibited significantly (P < 0.001) greater negative phonotaxis to the broadband sound (outboard motor recording) with an overall median response of 20 consecutive reactions during the 10 min trials. In over 50% of broadband sound tests, carp were still reacting to the stimulus at the end of the trial, implying that fish were not habituating to the sound. This study suggests that broadband sound may be an effective deterrent to bighead carp and provides a basis for conducting studies with wild fish.

  6. RF Performance of Layer-Structured Broadband Passive Millimeter-Wave Imaging System

    Directory of Open Access Journals (Sweden)

    Kunio Sakakibara

    2016-01-01

    Full Text Available Low profile and simple configuration are advantageous for RF module in passive millimeter-wave imaging system. High sensitivity over broad operation bandwidth is also necessary to detect right information from weak signal. We propose a broadband layer-structured module with low profile, simple structure, and ease of manufacture. This module is composed of a lens antenna and a detector module that consists of a detector circuit and a broadband microstrip-to-waveguide transition. The module forms a layer structure as a printed substrate with detector circuit is fixed between two metal plates with horn antennas and back-short waveguides. We developed a broadband passive millimeter-wave imaging module composed of a lens antenna and a detector module in this work. The gain and the antenna efficiency were measured, and the broadband operation was observed for the lens antenna. For the detector module, peak sensitivity was 8100 V/W. Furthermore, the detector module recognized a difference in the absorber’s temperature. The designs of the lens antenna and the detector module are presented and the RF performances of these components are reported. Finally, passive millimeter-wave imaging of a car, a human, and a metal plate in clothes is demonstrated in this paper.

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

    Science.gov (United States)

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

    2015-12-01

    The Headquarters for Earthquake Research Promotion (HERP) of Japan has organized the broadband ground motion simulation method into a standard procedure called the "recipe" (HERP, 2009). In the recipe, the source rupture is represented by the characterized source model (Irikura and Miyake, 2011). The broadband ground motion time histories are computed by a hybrid approach: the 3-D finite-difference method (Aoi et al. 2004) and the stochastic Green's function method (Dan and Sato, 1998; Dan et al. 2000) for the long- (> 1 s) and short-period (sites are well reproduced by the simulations. Then we evaluate 5% damped pseudo acceleration spectra (PSA) in the framework of the SCEC Broadband Platform (BBP) validation (Dreger et al. 2015). The validation results are generally acceptable in the period range 0.1 - 10 s, whereas those in the shortest period range (0.01-0.1 s) are less satisfactory. We also evaluate the simulations with the 1-D velocity structure models used in the SCEC BBP validation exercise. Although the goodness-of-fit parameters for PSA do not significantly differ from those for the 3-D velocity structure model, noticeable differences in velocity waveforms are observed. Our results suggest the importance of 1) well-constrained 3-D velocity structure model for broadband ground motion simulations and 2) evaluation of time series of ground motion as well as response spectra.

  8. Broadband absorber with periodically sinusoidally-patterned graphene layer in terahertz range.

    Science.gov (United States)

    Ye, Longfang; Chen, Yao; Cai, Guoxiong; Liu, Na; Zhu, Jinfeng; Song, Zhengyong; Liu, Qing Huo

    2017-05-15

    We demonstrate that a broadband terahertz absorber with near-unity absorption can be realized using a net-shaped periodically sinusoidally-patterned graphene sheet, placed on a dielectric spacer supported on a metallic reflecting plate. Because of the gradient width modulation of the unit graphene sheet, continuous plasmon resonances can be excited, and therefore broadband terahertz absorption can be achieved. The results show that the absorber's normalized bandwidth of 90% terahertz absorbance is over 65% under normal incidence for both TE and TM polarizations when the graphene chemical potential is set as 0.7 eV. And the broadband absorption is insensitive to the incident angles and the polarizations. The peak absorbance remains more than 70% over a wide range of the incident angles up to 60° for both polarizations. Furthermore, this absorber also has the advantage of flexible tunability via electrostatic doping of graphene sheet, which peak absorbance can be continuously tuned from 14% to 100% by controlling the chemical potential from 0 eV to 0.8 eV. The design scheme is scalable to develop various graphene-based tunable broadband absorbers at other terahertz, infrared, and visible frequencies, which may have promising applications in sensing, detecting, and optoelectronic devices.

  9. Computer Aided Design and Analysis of a 2-4 GHz Broadband Balanced Microstrip Amplifier

    Directory of Open Access Journals (Sweden)

    S. H. Ibrahim

    2012-07-01

    Full Text Available In this paper, a computer-aided design and analysis of a 2-4 GHz broadband balanced microstrip amplifier using a full computer simulation program developed by the author and others is presented. A short and efficient CAD procedure for broadband amplifier design is introduced. The first step is to design an initial narrow-band high gain microstrip amplifier at 3-GHz central frequency. The second step is to optimize the initial lengths and widths of the input and output microstrip-matching circuits to get the broadband amplifier over the range 2-4 GHz. The analysis of both narrow and broadband amplifiers is investigated. In addition, with the design and analysis of a low-pass microstrip filter, the paper introduces the design and analysis of a Lange coupler. The final AC schematic diagram of the designed amplifier with the lengths and widths of microstrip lines is presented.Key Words: Computer-Aided Design and Analysis, Microstrip Amplifier, Microwave Amplifier.

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

    DEFF Research Database (Denmark)

    Canning, John; Skivesen, Nina; Kristensen, Martin

    2007-01-01

    Both quasi-TE and TM polarisation spectra for a silicon- on-insulator (SOI) waveguide are recorded over (1100-1700) nm using a broadband supercontinuum source. By studying both the input and output polarisation eigenstates we observe narrowband resonant cross coupling near the lowest quasi-TE mode...

  11. 2010 E-Rate Program and Broadband Usage Survey: Report. DA 10-2414

    Science.gov (United States)

    Federal Communications Commission, 2010

    2010-01-01

    This report presents data from the "2010 E-rate Program and Broadband Usage Survey" commissioned by the Federal Communications Commission (FCC) and conducted by Harris Interactive, Inc. (Harris), an independent national marketing research firm, between February and April 2010. The primary goal of the survey was to collect data on the current state…

  12. Robust and fast schemes in broadband active noise and vibration control

    NARCIS (Netherlands)

    Fraanje, P.R.

    2004-01-01

    This thesis presents robust and fast active control algorithms for the suppression of broadband noise and vibration disturbances. Noise disturbances, e.g., generated by engines in airplanes and cars or by air ow, can be reduced by means of passive or active methods.

  13. Broadband in Schools: Effects on Student Performance and Spillovers for Household Internet Adoption

    Science.gov (United States)

    Belo, Rodrigo

    2012-01-01

    This work comprises studies on the effects of broadband Internet in schools at three different levels: student performance, household Internet adoption, and individual computer and Internet use patterns and skill acquisition. I focus in the case of Portugal, where by 2006 the Portuguese government had completed a major initiative that upgraded the…

  14. Towards Future Broadband Public Safety Systems: Current Issues and Future Directions

    DEFF Research Database (Denmark)

    Popovska Avramova, Andrijana; Ruepp, Sarah Renée; Dittmann, Lars

    2015-01-01

    The vision of the Fifth generation (5G) of mobile communication is that it will be an umbrella for communications for various vertical industries that have different requirements for delay, data rates, reliability, availability, and security. 5G will not be a single technology - rather a converge...... broadband trusted communication system for safety and critical missions...

  15. PLL application research of a broadband MEMS phase detector: Theory, measurement and modeling

    Science.gov (United States)

    Han, Juzheng; Liao, Xiaoping

    2017-06-01

    This paper evaluates the capability of a broadband MEMS phase detector in the application of phase locked loops (PLLs) through the aspect of theory, measurement and modeling. For the first time, it demonstrates how broadband property and optimized structure are realized through cascaded transmission lines and ANSYS simulations. The broadband MEMS phase detector shows potential in PLL application for its dc voltage output and large power handling ability which is important for munition applications. S-parameters of the power combiner in the MEMS phase detector are measured with S11 better than -15 dB and S23 better than -10 dB over the whole X-band. Compared to our previous works, developed phase detection measurements are performed and focused on signals at larger power levels up to 1 W. Cosine tendencies are revealed between the output voltage and the phase difference for both small and large signals. Simulation approach through equivalent circuit modeling is proposed to study the PLL application of the broadband MEMS phase detector. Synchronization and tracking properties are revealed.

  16. Broadband conformal phased array with optical beam forming for airborne satellite communication

    NARCIS (Netherlands)

    Schippers, H.; Verpoorte, J.; Jorna, P.; Hulzinga, A.; Meijerink, Arjan; Roeloffzen, C.G.H.; Zhuang, L.; Marpaung, D.A.I.; van Etten, Wim; Heideman, Rene; Leinse, Arne; Borreman, A.; Hoekman, M.; Wintels, M.

    2008-01-01

    For enhanced communication on board an aircraft, novel antenna systems with broadband satellite based capabilities are required. The technology will enhance airline operations by providing in-flight connectivity for flight crew information and will bring live TV and high speed Internet connectivity

  17. Erratum to “Ultra-Broadband Photonic Harmonic Mixer Based on Optical Comb Generation”

    DEFF Research Database (Denmark)

    Zhao, Ying; Pang, Xiaodan; Deng, Lei

    2012-01-01

    We propose a novel photonic harmonic mixer operating at frequencies up to the millimeter-wave (MMW) band. By combining a broadband fiber-wireless signal with highorder harmonics of a fundamental local oscillator in an optical frequency comb generator, frequency down-conversion can be implemented ...

  18. Broadband Microwave Wireless Power Transfer for Weak-Signal and Multipath Environments

    Science.gov (United States)

    Barton, Richard J.

    2014-01-01

    In this paper, we study the potential benefits of using relatively broadband wireless power transmission WPT strategies in both weak-signal and multipath environments where traditional narrowband strategies can be very inefficient. The paper is primarily a theoretical and analytical treatment of the problem that attempts to derive results that are widely applicable to many different WPT applications, including space solar power SSP.

  19. Analysis of discrete-time queue for broadband ISDN with priorities among traffic classes

    Science.gov (United States)

    Takine, Tetsuya; Sengupta, Bhaskar; Hasegawa, Toshiharu

    1994-02-01

    In Broadband ISDN (Integrated Service Digital Network), different classes of traffic expect to receive different quality of service. One way of providing service is to implement a priority structure among traffic classes. We analyze a single server queue in which video and voice traffic receive priority over data traffic.

  20. Broadband asymmetric transmission of linearly polarized electromagnetic waves based on chiral metamaterial

    Science.gov (United States)

    Stephen, Lincy; Yogesh, N.; Subramanian, V.

    2018-01-01

    The giant optical activity of chiral metamaterials (CMMs) holds great potential for tailoring the polarization state of an electromagnetic (EM) wave. In controlling the polarization state, the aspect of asymmetric transmission (AT), where a medium allows the EM radiation to pass through in one direction while restricting it in the opposite direction, adds additional degrees of freedom such as one-way channelling functionality. In this work, a CMM formed by a pair of mutually twisted slanted complementary metal strips is realized for broadband AT accompanied with cross-polarization (CP) conversion for linearly polarized EM waves. Numerically, the proposed ultra-thin (˜λ/42) CMM shows broadband AT from 8.58 GHz to 9.73 GHz (bandwidth of 1.15 GHz) accompanied with CP transmission magnitude greater than 0.9. The transmission and reflection spectra reveal the origin of the asymmetric transmission as the direction sensitive cross polarization conversion and anisotropic electric coupling occurring in the structure which is then elaborated with the surface current analysis and electric field distribution within the structure. An experiment is carried out to verify the broadband AT based CP conversion of the proposed CMM at microwave frequencies, and a reliable agreement between numerical and experimental results is obtained. Being ultra-thin, the reported broadband AT based CP conversion of the proposed CMM is useful for controlling radiation patterns in non-reciprocal EM devices and communication networks.