Improvements in speech understanding with wireless binaural broadband digital hearing instruments in adults with sensorineural hearing loss.

Science.gov (United States)

Kreisman, Brian M; Mazevski, Annette G; Schum, Donald J; Sockalingam, Ravichandran

2010-03-01

This investigation examined whether speech intelligibility in noise can be improved using a new, binaural broadband hearing instrument system. Participants were 36 adults with symmetrical, sensorineural hearing loss (18 experienced hearing instrument users and 18 without prior experience). Participants were fit binaurally in a planned comparison, randomized crossover design study with binaural broadband hearing instruments and advanced digital hearing instruments. Following an adjustment period with each device, participants underwent two speech-in-noise tests: the QuickSIN and the Hearing in Noise Test (HINT). Results suggested significantly better performance on the QuickSIN and the HINT measures with the binaural broadband hearing instruments, when compared with the advanced digital hearing instruments and unaided, across and within all noise conditions.

Study of Shortwave Spectra in Fully 3D Environment: Synergy Between Scanning Radars and Spectral Radiation Measurements

Science.gov (United States)

Wiscombe, Warren J.

2012-01-01

The main theme for our research is the understanding and closure of the surface spectral shortwave radiation problem in fully 3D cloud situations by combining the new ARM scanning radars, shortwave spectrometers, and microwave radiometers with the arsenal of radiative transfer tools developed by our group. In particular, we define first a large number of cloudy test cases spanning all 3D possibilities not just the customary uniform-overcast ones. Second, for each case, we define a "Best Estimate of Clouds That Affect Shortwave Radiation" using all relevant ARM instruments, notably the new scanning radars, and contribute this to the ARM Archive. Third, we test the ASR-signature radiative transfer model RRTMG_SW for those cases, focusing on the near-IR because of long-standing problems in this spectral region, and work with the developers to improve RRTMG_SW in order to increase its penetration into the modeling community.

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

Directory of Open Access Journals (Sweden)

Radiša R. Stefanović

2012-07-01

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

Broadband Access

Indian Academy of Sciences (India)

First page Back Continue Last page Overview Graphics. Broadband Access. Worldwide market for broadband access $30 Billion! Over 200 million broadband subscribers worldwide! Various Competing Broadband access. Digital Subscriber line; Wireless; Optical Fiber.

ARM Enhanced Shortwave Experiment (ARESE) Solar Radiation Data

Data.gov (United States)

National Aeronautics and Space Administration — The ARM Enhanced Shortwave Experiment (ARESE) was conducted at the Department of Energy's ARM Southern Great Plains (SGP) Central Facility between September 22, 1995...

Incoming Shortwave Fluxes at the Surface--A Comparison of GCM Results with Observations.

Science.gov (United States)

Garratt, J. R.

1994-01-01

Evidence is presented that the exam surface net radiation calculated in general circulation models at continental surfaces is mostly due to excess incoming shortwave fluxes. Based on long-term observations from 22 worldwide inland stations and results from four general circulation models the overestimate in models of 20% (11 W m2) in net radiation on an annual basis compares with 6% (9 W m2) for shortwave fluxes for the same 22 locations, or 9% (18 W m2) for a larger set of 93 stations (71 having shortwave fluxes only). For annual fluxes, these differences appear to be significant.

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

Sub-grid-scale effects on short-wave instability in magnetized hall-MHD plasma

International Nuclear Information System (INIS)

Miura, H.; Nakajima, N.

2010-11-01

Aiming to clarify effects of short-wave modes on nonlinear evolution/saturation of the ballooning instability in the Large Helical Device, fully three-dimensional simulations of the single-fluid MHD and the Hall MHD equations are carried out. A moderate parallel heat conductivity plays an important role both in the two kinds of simulations. In the single-fluid MHD simulations, the parallel heat conduction effectively suppresses short-wave ballooning modes but it turns out that the suppression is insufficient in comparison to an experimental result. In the Hall MHD simulations, the parallel heat conduction triggers a rapid growth of the parallel flow and enhance nonlinear couplings. A comparison between single-fluid and the Hall MHD simulations reveals that the Hall MHD model does not necessarily improve the saturated pressure profile, and that we may need a further extension of the model. We also find by a comparison between two Hall MHD simulations with different numerical resolutions that sub-grid-scales of the Hall term should be modeled to mimic an inverse energy transfer in the wave number space. (author)

Direct UV-written broadband directional broadband planar waveguide couplers

DEFF Research Database (Denmark)

Olivero, Massimo; Svalgaard, Mikael

2005-01-01

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

Handheld Broadband Electromagnetic UXO Sensor

National Research Council Canada - National Science Library

Won, I. J; San Filipo, William A; Marqusee, Jeffrey; Andrews, Anne; Robitaille, George; Fairbanks, Jeffrey; Overbay, Larry

2005-01-01

The broadband electromagnetic sensor improvement and demonstration undertaken in this project took the prototype GEM-3 and evolved it into an operational sensor with increased bandwidth and dynamic...

Factors affecting projected Arctic surface shortwave heating and albedo change in coupled climate models.

Science.gov (United States)

Holland, Marika M; Landrum, Laura

2015-07-13

We use a large ensemble of simulations from the Community Earth System Model to quantify simulated changes in the twentieth and twenty-first century Arctic surface shortwave heating associated with changing incoming solar radiation and changing ice conditions. For increases in shortwave absorption associated with albedo reductions, the relative influence of changing sea ice surface properties and changing sea ice areal coverage is assessed. Changes in the surface sea ice properties are associated with an earlier melt season onset, a longer snow-free season and enhanced surface ponding. Because many of these changes occur during peak solar insolation, they have a considerable influence on Arctic surface shortwave heating that is comparable to the influence of ice area loss in the early twenty-first century. As ice area loss continues through the twenty-first century, it overwhelms the influence of changes in the sea ice surface state, and is responsible for a majority of the net shortwave increases by the mid-twenty-first century. A comparison with the Arctic surface albedo and shortwave heating in CMIP5 models indicates a large spread in projected twenty-first century change. This is in part related to different ice loss rates among the models and different representations of the late twentieth century ice albedo and associated sea ice surface state. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Adoption of Broadband Services

DEFF Research Database (Denmark)

Falch, Morten

2008-01-01

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

Shortwave Array Spectroradiometer–Zenith (SASZe) Instrument Handbook

Energy Technology Data Exchange (ETDEWEB)

Flynn, Connor J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2016-04-01

The Shortwave Array Spectroradiometer – Zenith (SASZe) provides measurements of zenith spectral shortwave radiance at 1Hz over a continuous spectral range from approximately 300 nm to 1700 nm. The SASZe design connects an optical collector located outdoors to a pair of spectrometers and data collections system located indoors within a climate-controlled building via an umbilical cable of fiber optic and electrical cables. The light collector incorporates a collimator yielding a 1-degree Full Width at Half Maximum (FWHM) field of view. The data-acquisition electronics and spectrometers include an in-line fiber optic shutter and two Avantes fiber-coupled grating spectroradiometers within a temperature-controlled container. The Avantes Avaspec ULS 2048 charge-coupled device (CCD) spectrometer covers the wavelength range from about 300-1100 nm with a pixel spacing of less than 0.6 nm and a spectral resolution of about 2.4 nm FWHM. The Avantes Avaspec NIR256-1.7 spectrometer covers the wavelength range from about 950 nm to 1700 nm with a pixel spacing of less than 4 nm and a spectral resolution of about 6 nm FWHM.

Broadband infrared beam splitter for spaceborne interferometric infrared sounder.

Science.gov (United States)

Yu, Tianyan; Liu, Dingquan; Qin, Yang

2014-10-01

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

ENSO surface shortwave radiation forcing over the tropical Pacific

Directory of Open Access Journals (Sweden)

K. G. Pavlakis

2008-09-01

Full Text Available We have studied the spatial and temporal variation of the downward shortwave radiation (DSR at the surface of the Earth during ENSO events for a 21-year period over the tropical and subtropical Pacific Ocean (40° S–40° N, 90° E–75° W. The fluxes were computed using a deterministic model for atmospheric radiation transfer, along with satellite data from the ISCCP-D2 database, reanalysis data from NCEP/NCAR for the key atmospheric and surface input parameters, and aerosol parameters from GADS (acronyms explained in main text. A clear anti-correlation was found between the downward shortwave radiation anomaly (DSR-A time-series, in the region 7° S–5° N 160° E–160° W located west of the Niño-3.4 region, and the Niño-3.4 index time-series. In this region where the highest in absolute value DSR anomalies are observed, the mean DSR anomaly values range from −45 Wm⁻² during El Niño episodes to +40 Wm⁻² during La Niña events. Within the Niño-3.4 region no significant DSR anomalies are observed during the cold ENSO phase in contrast to the warm ENSO phase. A high correlation was also found over the western Pacific (10° S–5° N, 120–140° E, where the mean DSR anomaly values range from +20 Wm⁻² to −20 Wm⁻² during El Niño and La Niña episodes, respectively. There is also convincing evidence that the time series of the mean downward shortwave radiation anomaly in the off-equatorial western Pacific region 7–15° N 150–170° E, precedes the Niño-3.4 index time-series by about 7 months and the pattern of this anomaly is indicative of ENSO operating through the mechanism of the western Pacific oscillator. Thus, the downward shortwave radiation anomaly is a complementary index to the SST anomaly for the study of ENSO events and can be used to assess whether or not El Niño or La Niña conditions prevail.

Improved Correction of IR Loss in Diffuse Shortwave Measurements: An ARM Value-Added Product

Energy Technology Data Exchange (ETDEWEB)

Younkin, K; Long, CN

2003-11-01

Simple single black detector pyranometers, such as the Eppley Precision Spectral Pyranometer (PSP) used by the Atmospheric Radiation Measurement (ARM) Program, are known to lose energy via infrared (IR) emission to the sky. This is especially a problem when making clear-sky diffuse shortwave (SW) measurements, which are inherently of low magnitude and suffer the greatest IR loss. Dutton et al. (2001) proposed a technique using information from collocated pyrgeometers to help compensate for this IR loss. The technique uses an empirically derived relationship between the pyrgeometer detector data (and alternatively the detector data plus the difference between the pyrgeometer case and dome temperatures) and the nighttime pyranometer IR loss data. This relationship is then used to apply a correction to the diffuse SW data during daylight hours. We developed an ARM value-added product (VAP) called the SW DIFF CORR 1DUTT VAP to apply the Dutton et al. correction technique to ARM PSP diffuse SW measurements.

Arctic atmospheric preconditioning: do not rule out shortwave radiation just yet

Science.gov (United States)

Sedlar, J.

2017-12-01

Springtime atmospheric preconditioning of Arctic sea ice for enhanced or buffered sea ice melt during the subsequent melt year has received considerable research focus in recent years. A general consensus points to enhanced poleward atmospheric transport of moisture and heat during spring, effectively increasing the emission of longwave radiation to the surface. Studies have essentially ruled out the role of shortwave radiation as an effective preconditioning mechanism because of the relatively weak incident solar radiation and high surface albedo from sea ice and snow during spring. These conclusions, however, are derived primarily from atmospheric reanalysis data, which may not always represent an accurate depiction of the Arctic climate system. Here, observations of top of atmosphere radiation from state of the art satellite sensors are examined and compared with reanalysis and climate model data to examine the differences in the spring radiative budget over the Arctic Ocean for years with extreme low/high ice extent at the end of the ice melt season (September). Distinct biases are observed between satellite-based measurements and reanalysis/models, particularly for the amount of shortwave radiation trapped (warming effect) within the Arctic climate system during spring months. A connection between the differences in reanalysis/model surface albedo representation and the albedo observed by satellite is discussed. These results suggest that shortwave radiation should not be overlooked as a significant contributing mechanism to springtime Arctic atmospheric preconditioning.

Top-down and bottom-up aerosol-cloud closure: towards understanding sources of uncertainty in deriving cloud shortwave radiative flux

Science.gov (United States)

Sanchez, Kevin J.; Roberts, Gregory C.; Calmer, Radiance; Nicoll, Keri; Hashimshoni, Eyal; Rosenfeld, Daniel; Ovadnevaite, Jurgita; Preissler, Jana; Ceburnis, Darius; O'Dowd, Colin; Russell, Lynn M.

2017-08-01

Top-down and bottom-up aerosol-cloud shortwave radiative flux closures were conducted at the Mace Head Atmospheric Research Station in Galway, Ireland, in August 2015. This study is part of the BACCHUS (Impact of Biogenic versus Anthropogenic emissions on Clouds and Climate: towards a Holistic UnderStanding) European collaborative project, with the goal of understanding key processes affecting aerosol-cloud shortwave radiative flux closures to improve future climate predictions and develop sustainable policies for Europe. Instrument platforms include ground-based unmanned aerial vehicles (UAVs)1 and satellite measurements of aerosols, clouds and meteorological variables. The ground-based and airborne measurements of aerosol size distributions and cloud condensation nuclei (CCN) concentration were used to initiate a 1-D microphysical aerosol-cloud parcel model (ACPM). UAVs were equipped for a specific science mission, with an optical particle counter for aerosol distribution profiles, a cloud sensor to measure cloud extinction or a five-hole probe for 3-D wind vectors. UAV cloud measurements are rare and have only become possible in recent years through the miniaturization of instrumentation. These are the first UAV measurements at Mace Head. ACPM simulations are compared to in situ cloud extinction measurements from UAVs to quantify closure in terms of cloud shortwave radiative flux. Two out of seven cases exhibit sub-adiabatic vertical temperature profiles within the cloud, which suggests that entrainment processes affect cloud microphysical properties and lead to an overestimate of simulated cloud shortwave radiative flux. Including an entrainment parameterization and explicitly calculating the entrainment fraction in the ACPM simulations both improved cloud-top radiative closure. Entrainment reduced the difference between simulated and observation-derived cloud-top shortwave radiative flux (δRF) by between 25 and 60 W m-2. After accounting for entrainment

An improved broadband E patch microstrip antenna for wireless communications

Science.gov (United States)

Bzeih, Amer; Chahine, Soubhi Abou; Kabalan, Karim Y.; El-Hajj, Ali; Chehab, Ali

2007-12-01

A broadband probe-fed microstrip antenna with E-shaped patch on a single-layer air substrate is investigated. Bandwidth enhancement of the antenna is achieved by inserting two parallel slots into its radiating patch. The effects of the antenna parameters are analyzed, and their optimal values for broadband operation are obtained. The design parameters are formulated as a function of the center frequency, and the empirical equations are validated by simulation. A 51.5% enhanced E patch antenna for modern wireless communications (Personal Communications Service, Digital Cellular System, Universal Mobile Telecommunications System, Wireless Local Area Network 802.11 b/g, and Bluetooth) is designed, simulated, fabricated, and measured. A comparison between simulated and measured results is presented, and it showed satisfactory agreement. Moreover, the effect of incorporating more parallel slots into the radiating patch is investigated. The antenna is designed and simulated for different scenarios (four slots, six slots, and eight slots), where a bandwidth of 57% is achieved in the eight-slot design.

Broadband enhancement of infrared absorption in microbolometers using Ag nanocrystals

International Nuclear Information System (INIS)

Hyun, Jerome K.; Ahn, Chi Won; Kim, Woo Choong; Kim, Tae Hyun; Hyun, Moon Seop; Kim, Hee Yeoun; Park, Jae Hong; Lee, Won-Oh

2015-01-01

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

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.

TAO/TRITON, RAMA, and PIRATA Buoys, Daily, 1991-present, Downgoing Shortwave Radiation

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has daily Downgoing Shortwave Radiation data from the TAO/TRITON (Pacific Ocean, https://www.pmel.noaa.gov/gtmba/ ), RAMA (Indian Ocean,...

TAO/TRITON, RAMA, and PIRATA Buoys, Monthly, 1991-present, Net Shortwave Radiation

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has monthly Net Shortwave Radiation data from the TAO/TRITON (Pacific Ocean, https://www.pmel.noaa.gov/gtmba/ ), RAMA (Indian Ocean,...

Sensitivity of MENA Tropical Rainbelt to Dust Shortwave Absorption: A High Resolution AGCM Experiment

KAUST Repository

Bangalath, Hamza Kunhu; Stenchikov, Georgiy L.

2016-01-01

Shortwave absorption is one of the most important, but the most uncertain, components of direct radiative effect by mineral dust. It has a broad range of estimates from different observational and modeling studies and there is no consensus on the strength of absorption. To elucidate the sensitivity of the Middle East and North Africa (MENA) tropical summer rainbelt to a plausible range of uncertainty in dust shortwave absorption, AMIP-style global high resolution (25 km) simulations are conducted with and without dust, using the High-Resolution Atmospheric Model (HiRAM). Simulations with dust comprise three different cases by assuming dust as a very efficient, standard and inefficient absorber. Inter-comparison of these simulations shows that the response of the MENA tropical rainbelt is extremely sensitive to the strength of shortwave absorption. Further analyses reveal that the sensitivity of the rainbelt stems from the sensitivity of the multi-scale circulations that define the rainbelt. The maximum response and sensitivity are predicted over the northern edge of the rainbelt, geographically over Sahel. The sensitivity of the responses over the Sahel, especially that of precipitation, is comparable to the mean state. Locally, the response in precipitation reaches up to 50% of the mean, while dust is assumed to be a very efficient absorber. Taking into account that Sahel has a very high climate variability and is extremely vulnerable to changes in precipitation, the present study suggests the importance of reducing uncertainty in dust shortwave absorption for a better simulation and interpretation of the Sahel climate.

Sensitivity of MENA Tropical Rainbelt to Dust Shortwave Absorption: A High Resolution AGCM Experiment

KAUST Repository

Bangalath, Hamza Kunhu

2016-06-13

Shortwave absorption is one of the most important, but the most uncertain, components of direct radiative effect by mineral dust. It has a broad range of estimates from different observational and modeling studies and there is no consensus on the strength of absorption. To elucidate the sensitivity of the Middle East and North Africa (MENA) tropical summer rainbelt to a plausible range of uncertainty in dust shortwave absorption, AMIP-style global high resolution (25 km) simulations are conducted with and without dust, using the High-Resolution Atmospheric Model (HiRAM). Simulations with dust comprise three different cases by assuming dust as a very efficient, standard and inefficient absorber. Inter-comparison of these simulations shows that the response of the MENA tropical rainbelt is extremely sensitive to the strength of shortwave absorption. Further analyses reveal that the sensitivity of the rainbelt stems from the sensitivity of the multi-scale circulations that define the rainbelt. The maximum response and sensitivity are predicted over the northern edge of the rainbelt, geographically over Sahel. The sensitivity of the responses over the Sahel, especially that of precipitation, is comparable to the mean state. Locally, the response in precipitation reaches up to 50% of the mean, while dust is assumed to be a very efficient absorber. Taking into account that Sahel has a very high climate variability and is extremely vulnerable to changes in precipitation, the present study suggests the importance of reducing uncertainty in dust shortwave absorption for a better simulation and interpretation of the Sahel climate.

Top-down and bottom-up aerosol–cloud closure: towards understanding sources of uncertainty in deriving cloud shortwave radiative flux

Directory of Open Access Journals (Sweden)

K. J. Sanchez

2017-08-01

Full Text Available Top-down and bottom-up aerosol–cloud shortwave radiative flux closures were conducted at the Mace Head Atmospheric Research Station in Galway, Ireland, in August 2015. This study is part of the BACCHUS (Impact of Biogenic versus Anthropogenic emissions on Clouds and Climate: towards a Holistic UnderStanding European collaborative project, with the goal of understanding key processes affecting aerosol–cloud shortwave radiative flux closures to improve future climate predictions and develop sustainable policies for Europe. Instrument platforms include ground-based unmanned aerial vehicles (UAVs1 and satellite measurements of aerosols, clouds and meteorological variables. The ground-based and airborne measurements of aerosol size distributions and cloud condensation nuclei (CCN concentration were used to initiate a 1-D microphysical aerosol–cloud parcel model (ACPM. UAVs were equipped for a specific science mission, with an optical particle counter for aerosol distribution profiles, a cloud sensor to measure cloud extinction or a five-hole probe for 3-D wind vectors. UAV cloud measurements are rare and have only become possible in recent years through the miniaturization of instrumentation. These are the first UAV measurements at Mace Head. ACPM simulations are compared to in situ cloud extinction measurements from UAVs to quantify closure in terms of cloud shortwave radiative flux. Two out of seven cases exhibit sub-adiabatic vertical temperature profiles within the cloud, which suggests that entrainment processes affect cloud microphysical properties and lead to an overestimate of simulated cloud shortwave radiative flux. Including an entrainment parameterization and explicitly calculating the entrainment fraction in the ACPM simulations both improved cloud-top radiative closure. Entrainment reduced the difference between simulated and observation-derived cloud-top shortwave radiative flux (δRF by between 25 and 60 W m−2. After

Some observations on stray magnetic fields and power outputs from short-wave diathermy equipment

Energy Technology Data Exchange (ETDEWEB)

Lau, R.W.M.; Dunscombe, P.B.

1984-04-01

Recent years have seen increasing interest in the possible hazards arising from the use of nonionizing electromagnetic radiation. Relatively large and potentially hazardous fields are to be found in the vicinity of short-wave and microwave equipment used in physiotherapy departments to produce therapeutic temperature rises. This note reports the results of measurements of the stray magnetic field and power output of a conventional short-wave diathermy unit when applied to tissue-equivalent phantoms. The dependence of these quantities on the variables, i.e. power setting of the unit, capacitor plate size, phantom size and phantom-capacitor plate separation, are discussed.

Handheld, Broadband Electromagnetic UXO Sensor: Cost & Performance Report

National Research Council Canada - National Science Library

Won, I. J; SanFilipo, Bill; Oren, Alex

2006-01-01

The broadband electromagnetic sensor improvement and demonstration undertaken in this project took the prototype GEM-3 and evolved it into an operational sensor with increased bandwidth and dynamic...

Leaf temperature and transpiration of rice plants in relation to short-wave radiation and wind speed

International Nuclear Information System (INIS)

Ito, D.; Haseba, T.

1984-01-01

Leaf temperature and transpiration amount of rice plants were measured in a steady environment in a laboratory and in field situations. The plants set in Wagner pots were used. Experiments were carried out at the tillering and booting stages, and on the date of maturity. Measured leaf temperatures and transpiration rates were analyzed in connection with incident short-wave radiation on a leaf and wind speed measured simultaneously.Instantaneous supplying and turning-off of steady artificial light caused cyclic changes in leaf temperature and transpiration. Leaf temperature dropped in feeble illumination compared with the steady temperature in the preceeding dark.On the date of maturity, a rice plant leaf was warmer than the air, even in feeble light. Then, the leaf-air temperature difference and transpiration rate showed approximately linear increases with short-wave radiation intensity. On the same date, an increase in wind speed produced a decrease in leaf-air temperature difference, i.e., leaf temperature dropped, and an increase in transpiration rate. The rates of both changes in leaf temperature and transpiration rate were fairly large in a range of wind speed below about 1m/s.For rice plants growing favorably from the tillering stage through the booting stage, the leaves were considerably cooler than the air, even in an intense light and/or solar radiation. The leaf temperature showed the lowest value at short-wave radiations between 0.15 and 0.20ly/min, at above which the leaf temperature rised with an increase in short-wave radiation until it approached the air temperature. Transpiration rate of rice plants increased rapidly with an increase in short-wave radiation ranging below 0.2 or 0.3ly/min, at above which the increase in transpiration rate slowed.The relationships between leaf temperature and/or transpiration rate and wind speed and/or incident short-wave radiation (solar radiation) which were obtained experimentally, supported the relationships

Broadband Faraday isolator.

Science.gov (United States)

Berent, Michał; Rangelov, Andon A; Vitanov, Nikolay V

2013-01-01

Driving on an analogy with the technique of composite pulses in quantum physics, we theoretically propose a broadband Faraday rotator and thus a broadband optical isolator, which is composed of sequences of ordinary Faraday rotators and achromatic quarter-wave plates rotated at the predetermined angles.

Short-wave albedo of a pine forest

Energy Technology Data Exchange (ETDEWEB)

Kessler, A.

1985-06-01

In this paper nine years of continuous records of the short-wave albedo above a Scotch pine forest in middle Europe were analysed. Special emphasis was given to the dependencies of the albedo on its diurnal variation, its annual variation, the solar altitude, the structure of the stand, the cloud cover, the soil moisture and the spectral reflectance. A long-termed trend of the albedo could not be found, e.g. caused by the stand growth. Finally the annual variation of the albedo of the Scotch pine forest was compared with measurements above different surface types in middle Europe.

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.

2016-09-01

At present, broadband radiometric LED measurements 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.

Broadband Internet and Income Inequality

OpenAIRE

HOUNGBONON , Georges Vivien; Liang , Julienne

2017-01-01

Policy makers are aiming for a large coverage of high-speed broadband Internet. However , there is still a lack of evidence about its effects on income distribution. In this paper, we investigate the effects of fixed broadband Internet on mean income and income inequality using a unique town-level data on broadband adoption and quality in France. We find that broadband adoption and quality raise mean income and lower income inequality. These results are robust to initial conditions, and yield...

A Novel Method for Estimating Shortwave Direct Radiative Effect of Above-Cloud Aerosols Using CALIOP and MODIS Data

Science.gov (United States)

Zhang, Z.; Meyer, K.; Platnick, S.; Oreopoulos, L.; Lee, D.; Yu, H.

2014-01-01

This paper describes an efficient and unique method for computing the shortwave direct radiative effect (DRE) of aerosol residing above low-level liquid-phase clouds using CALIOP and MODIS data. It accounts for the overlapping of aerosol and cloud rigorously by utilizing the joint histogram of cloud optical depth and cloud top pressure. Effects of sub-grid scale cloud and aerosol variations on DRE are accounted for. It is computationally efficient through using grid-level cloud and aerosol statistics, instead of pixel-level products, and a pre-computed look-up table in radiative transfer calculations. We verified that for smoke over the southeast Atlantic Ocean the method yields a seasonal mean instantaneous shortwave DRE that generally agrees with more rigorous pixel-level computation within 4. We have also computed the annual mean instantaneous shortwave DRE of light-absorbing aerosols (i.e., smoke and polluted dust) over global ocean based on 4 yr of CALIOP and MODIS data. We found that the variability of the annual mean shortwave DRE of above-cloud light-absorbing aerosol is mainly driven by the optical depth of the underlying clouds.

A hybrid optical system for broadband imaging in guidance and control

Science.gov (United States)

Wu, Xiaofang; Jiang, Yuesong; Shen, Chunyan; Zhao, Yiming

2006-11-01

A binary optics method has been adopted to improve upon a conventional optical system in guidance and control, and a hybrid broadband imaging system that includes a binary surface is analyzed and evaluated by optical design software ZEMAX. The practical design shows that the introduction of binary optics can simplify the structure of the imaging system and reduce the size and weight of the broadband guidance and control system. Moreover, it can help to acquire images of radiation of different wavelengths from targets; hence it will result in improved overall performance of missiles in wars.

Net Surface Shortwave Radiation from GOES Imagery—Product Evaluation Using Ground-Based Measurements from SURFRAD

Directory of Open Access Journals (Sweden)

Anand K. Inamdar

2015-08-01

Full Text Available The Earth’s surface net radiation controls the energy and water exchanges between the Earth’s surface and the atmosphere, and can be derived from satellite observations. The ability to monitor the net surface radiation over large areas at high spatial and temporal resolution is essential for many applications, such as weather forecasting, short-term climate prediction or water resources management. The objective of this paper is to derive the net surface radiation in the shortwave domain at high temporal (half-hourly and spatial resolution (~1 km using visible imagery from Geostationary Operational Environmental Satellite (GOES. The retrieval algorithm represents an adaptation to GOES data of a standard algorithm initially developed for the NASA-operated Clouds and Earth’s Radiant Energy System (CERES scanner. The methodology relies on: (1 the estimation of top of atmosphere shortwave radiation from GOES spectral measurements; and (2 the calculation of net surface shortwave (SW radiation accounting for atmospheric effects. Comparison of GOES-retrieved net surface shortwave radiation with ground-measurements at the National Oceanic and Atmospheric Administration’s (NOAA Surface Radiation (SURFRAD stations yields very good agreement with average bias lower than 5 W·m−2 and root mean square difference around 70 W·m−2. The algorithm performance is usually higher over areas characterized by low spatial variability in term of land cover type and surface biophysical properties. The technique does not involve retrieval and assessment of cloud properties and can be easily adapted to other meteorological satellites around the globe.

Broadband Radiometric LED Measurements

OpenAIRE

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(��) 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 irr...

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 ...

Design and fabrication of broadband rugate filter

International Nuclear Information System (INIS)

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

2012-01-01

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

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.

Sensitivity of tropical rainbelt over Africa and Middle East to dust shortwave absorption: Experiments using a high resolution AGCM

KAUST Repository

Bangalath, Hamza Kunhu; Stenchikov, Georgiy L.

2015-01-01

Response of the rainbelt over Africa to dust direct radiative forcing has been an area of lively debate and is a subject of ongoing research. Previous modeling studies have contrasting results producing different amplitudes or even signs of responses. Uncertainties in the dust radiative forcing are thought to be the major cause of discrepancies in the simulated responses among various studies. The imaginary part of mineral dust shortwave refractive index, which defines the dust absorptivity, has a wide range of values estimated from various observational and modeling studies, as it depends on dust chemical composition and mineralogy. Balkanski et al. (2007) estimated dust shortwave refractive indices by assuming 3 different hematite contents, 0.9%, 1.5% and 2.7% by volume, which corresponds to inefficient, standard, and very efficient dust shortwave absorption, respectively. To investigate the sensitivity of the position and intensity of the tropical rainbelt over Africa and its extension to the Arabian Peninsula to dust shortwave absorption, we have conducted ensembles of numerical simulations for each of the three dust absorptivity scenarios using a high resolution Atmospheric General Circulation Model (AGCM), GFDL's High Resolution Atmospheric Model (HiRAM), at a spatial resolution of 25 km. We found that the strength and the latitudinal extent of the rainbelt are very sensitive to dust shortwave absorption, as well as circulations at various spatiotemporal scales that drive the climate of the region. Reference: Balkanski, Y., M. Schulz, T. Claquin, and S. Guibert (2007), Reevaluation of mineral aerosol radiative forcings suggests a better agreement with satellite and AERONET data, Atmos. Chem. Phys., 7, 81 - 95.

Modeling of Broadband Liners Applied to the Advanced Noise Control Fan

Science.gov (United States)

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

2015-01-01

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

Broadband electrical impedance matching for piezoelectric ultrasound transducers.

Science.gov (United States)

Huang, Haiying; Paramo, Daniel

2011-12-01

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

Estimating net short-wave radiation with the Bellani pyranometer

International Nuclear Information System (INIS)

Bernier, Y.; Plamondon, A.P.

1983-01-01

Two methods were developed by which daily net short-wave radiation (K∗) can be evaluated from Bellani pyranometer readings. The first method involves a simple regression equation. The second method uses a physical approach taking into account the effect of the Bellani's geometry on its response to direct and diffuse radiation throughout the day. Both methods, when tested on experimental data, tended to underestimate the measured K∗, the regression approach exhibiting a higher variance of the error [fr

Broadband standard dipole antenna for antenna calibration

Science.gov (United States)

Koike, Kunimasa; Sugiura, Akira; Morikawa, Takao

1995-06-01

Antenna calibration of EMI antennas is mostly performed by the standard antenna method at an open-field test site using a specially designed dipole antenna as a reference. In order to develop broadband standard antennas, the antenna factors of shortened dipples are theoretically investigated. First, the effects of the dipole length are analyzed using the induced emf method. Then, baluns and loads are examined to determine their influence on the antenna factors. It is found that transformer-type baluns are very effective for improving the height dependence of the antenna factors. Resistive loads are also useful for flattening the frequency dependence. Based on these studies, a specification is developed for a broadband standard antenna operating in the 30 to 150 MHz frequency range.

Sensitivity of tropical rainbelt over Africa and Middle East to dust shortwave absorption: Experiments using a high resolution AGCM

KAUST Repository

Bangalath, Hamza Kunhu

2015-04-01

Response of the rainbelt over Africa to dust direct radiative forcing has been an area of lively debate and is a subject of ongoing research. Previous modeling studies have contrasting results producing different amplitudes or even signs of responses. Uncertainties in the dust radiative forcing are thought to be the major cause of discrepancies in the simulated responses among various studies. The imaginary part of mineral dust shortwave refractive index, which defines the dust absorptivity, has a wide range of values estimated from various observational and modeling studies, as it depends on dust chemical composition and mineralogy. Balkanski et al. (2007) estimated dust shortwave refractive indices by assuming 3 different hematite contents, 0.9%, 1.5% and 2.7% by volume, which corresponds to inefficient, standard, and very efficient dust shortwave absorption, respectively. To investigate the sensitivity of the position and intensity of the tropical rainbelt over Africa and its extension to the Arabian Peninsula to dust shortwave absorption, we have conducted ensembles of numerical simulations for each of the three dust absorptivity scenarios using a high resolution Atmospheric General Circulation Model (AGCM), GFDL\\'s High Resolution Atmospheric Model (HiRAM), at a spatial resolution of 25 km. We found that the strength and the latitudinal extent of the rainbelt are very sensitive to dust shortwave absorption, as well as circulations at various spatiotemporal scales that drive the climate of the region. Reference: Balkanski, Y., M. Schulz, T. Claquin, and S. Guibert (2007), Reevaluation of mineral aerosol radiative forcings suggests a better agreement with satellite and AERONET data, Atmos. Chem. Phys., 7, 81 - 95.

A Novel Method for Estimating Shortwave Direct Radiative Effect of Above-cloud Aerosols over Ocean Using CALIOP and MODIS Data

Science.gov (United States)

Zhang, Z.; Meyer, K.; Platnick, S.; Oreopoulos, L.; Lee, D.; Yu, H.

2013-01-01

This paper describes an efficient and unique method for computing the shortwave direct radiative effect (DRE) of aerosol residing above low-level liquid-phase clouds using CALIOP and MODIS data. It accounts for the overlapping of aerosol and cloud rigorously by utilizing the joint histogram of cloud optical depth and cloud top pressure. Effects of sub-grid scale cloud and aerosol variations on DRE are accounted for. It is computationally efficient through using grid-level cloud and aerosol statistics, instead of pixel-level products, and a pre-computed look-up table in radiative transfer calculations. We verified that for smoke over the southeast Atlantic Ocean the method yields a seasonal mean instantaneous shortwave DRE that generally agrees with more rigorous pixel-level computation within 4%. We have also computed the annual mean instantaneous shortwave DRE of light-absorbing aerosols (i.e., smoke and polluted dust) over global ocean based on 4 yr of CALIOP and MODIS data. We found that the variability of the annual mean shortwave DRE of above-cloud light-absorbing aerosol is mainly driven by the optical depth of the underlying clouds.

Characterizing the information content of cloud thermodynamic phase retrievals from the notional PACE OCI shortwave reflectance measurements

Science.gov (United States)

Coddington, O. M.; Vukicevic, T.; Schmidt, K. S.; Platnick, S.

2017-08-01

We rigorously quantify the probability of liquid or ice thermodynamic phase using only shortwave spectral channels specific to the National Aeronautics and Space Administration's Moderate Resolution Imaging Spectroradiometer, Visible Infrared Imaging Radiometer Suite, and the notional future Plankton, Aerosol, Cloud, ocean Ecosystem imager. The results show that two shortwave-infrared channels (2135 and 2250 nm) provide more information on cloud thermodynamic phase than either channel alone; in one case, the probability of ice phase retrieval increases from 65 to 82% by combining 2135 and 2250 nm channels. The analysis is performed with a nonlinear statistical estimation approach, the GEneralized Nonlinear Retrieval Analysis (GENRA). The GENRA technique has previously been used to quantify the retrieval of cloud optical properties from passive shortwave observations, for an assumed thermodynamic phase. Here we present the methodology needed to extend the utility of GENRA to a binary thermodynamic phase space (i.e., liquid or ice). We apply formal information content metrics to quantify our results; two of these (mutual and conditional information) have not previously been used in the field of cloud studies.

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...

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...

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

Background estimation in short-wave region during determination of total sample composition by x-ray fluorescence method

International Nuclear Information System (INIS)

Simakov, V.A.; Kordyukov, S.V.; Petrov, E.N.

1988-01-01

Method of background estimation in short-wave spectral region during determination of total sample composition by X-ray fluorescence method is described. 13 types of different rocks with considerable variations of base composition and Zr, Nb, Th, U content below 7x10 -3 % are investigated. The suggested method of background accounting provides for a less statistical error of the background estimation than direct isolated measurement and reliability of its determination in a short-wave region independent on the sample base. Possibilities of suggested method for artificial mixtures conforming by the content of main component to technological concemtrates - niobium, zirconium, tantalum are estimated

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...

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...

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

[Determination of fat, protein and DM in raw milk by portable short-wave near infrared spectrometer].

Science.gov (United States)

Li, Xiao-yun; Wang, Jia-hua; Huang, Ya-wei; Han, Dong-hai

2011-03-01

Near infrared diffuse reflectance spectroscopy calibrations of fat, protein and DM in raw milk were studied with partial least-squares (PLS) regression using portable short-wave near infrared spectrometer. The results indicated that good calibrations of fat and DM were found, the correlation coefficients were all 0.98, the RMSEC were 0.187 and 0.217, RMSEP were 0.187 and 0.296, the RPDs were 5.02 and 3.20 respectively; the calibration of protein needed to be improved but can be used for practice, the correlation coefficient was 0.95, RMSEC was 0.105, RMSEP was 0.120, and RPD was 2.60. Furthermore, the measuring accuracy was improved by analyzing the correction relation of fat and DM in raw milk This study will probably provide a new on-site method for nondestructive and rapid measurement of milk.

Determine Daytime Earth's Radiation Budget from DSCOVR

Science.gov (United States)

Su, W.; Thieman, M. M.; Duda, D. P.; Khlopenkov, K. V.; Liang, L.; Sun-Mack, S.; Minnis, P.; SUN, M.

2017-12-01

The Deep Space Climate Observatory (DSCOVR) platform provides a unique perspective for remote sensing of the Earth. With the National Institute of Standards and Technology Advanced Radiometer (NISTAR) and the Earth Polychromatic Imaging Camera (EPIC) onboard, it provides full-disk measurements of the broadband shortwave and total radiances reaching the L1 position. Because the satellite orbits around the L1 spot, it continuously observes a nearly full Earth, providing the potential to determine the daytime radiation budget of the globe at the top of the atmosphere. The NISTAR is a single-pixel instrument that measures the broadband radiance from the entire globe, while EPIC is a spectral imager with channels in the UV and visible ranges. The Level 1 NISTAR shortwave radiances are filtered radiances. To determine the daytime TOA shortwave and longwave radiative fluxes, the NISTAR measured shortwave radiances must be unfiltered first. We will describe the algorithm used to un-filter the shortwave radiances. These unfiltered NISTAR radiances are then converted to the full disk shortwave and daytime longwave fluxes, by accounting for the anisotropic characteristics of the Earth-reflected and emitted radiances. These anisotropy factors are determined by using the scene identifications determined from multiple low Earth orbit and geostationary satellites matched into the EPIC field of view. Time series of daytime radiation budget determined from NISTAR will be presented, and methodology of estimating the fluxes from the small unlit crescent of the Earth that comprises part of the field of view will also be described. The daytime shortwave and longwave fluxes from NISTAR will be compared with CERES dataset.

Evaluation of the shortwave cloud radiative effect over the ocean by use of ship and satellite observations

Directory of Open Access Journals (Sweden)

T. Hanschmann

2012-12-01

Full Text Available In this study the shortwave cloud radiative effect (SWCRE over ocean calculated by the ECHAM 5 climate model is evaluated for the cloud property input derived from ship based measurements and satellite based estimates and compared to ship based radiation measurements. The ship observations yield cloud fraction, liquid water path from a microwave radiometer, cloud bottom height as well as temperature and humidity profiles from radiosonde ascents. Level-2 products of the Satellite Application Facility on Climate Monitoring (CM~SAF from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI have been used to characterize clouds. Within a closure study six different experiments have been defined to find the optimal set of measurements to calculate downward shortwave radiation (DSR and the SWCRE from the model, and their results have been evaluated under seven different synoptic situations. Four of these experiments are defined to investigate the advantage of including the satellite-based cloud droplet effective radius as additional cloud property. The modeled SWCRE based on satellite retrieved cloud properties has a comparable accuracy to the modeled SWCRE based on ship data. For several cases, an improvement through introducing the satellite-based estimate of effective radius as additional information to the ship based data was found. Due to their different measuring characteristics, however, each dataset shows best results for different atmospheric conditions.

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.

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

Broadband solar absorption enhancement via periodic nanostructuring of electrodes.

KAUST Repository

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

2013-01-01

Solution processed colloidal quantum dot (CQD) solar cells have great potential for large area low-cost photovoltaics. However, light utilization remains low mainly due to the tradeoff between small carrier transport lengths and longer infrared photon absorption lengths. Here, we demonstrate a bottom-illuminated periodic nanostructured CQD solar cell that enhances broadband absorption without compromising charge extraction efficiency of the device. We use finite difference time domain (FDTD) simulations to study the nanostructure for implementation in a realistic device and then build proof-of-concept nanostructured solar cells, which exhibit a broadband absorption enhancement over the wavelength range of λ = 600 to 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.

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.

Advent of broadband public-switched communications

Science.gov (United States)

Casey, John J.

1992-02-01

Advances in data communications infrastructure, display technology, and man-machine interfaces have changed business applications and the requirements of public network data transport. These changes have created opportunities for a new generation of public broadband services to more efficiently extend high speed communications capabilities beyond the customer premises. This paper provides a view of the technology and market evolution of these public broadband data communications services, and suggests early customer networked applications that justify the deployment of a public switched broadband network infrastructure.

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.

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...

Measuring Earth's Radiation Budget from the Vicinity of the Moon

Science.gov (United States)

Swartz, W. H.; Lorentz, S. R.; Erlandson, R. E.; Cahalan, R. F.; Huang, P. M.

2018-02-01

We propose to measure Earth's radiation budget (integrated total and solar-reflected shortwave) using broadband radiometers and other technology demonstrated in space. The instrument is compact, autonomous, and has modest resource requirements.

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.

Chaos-assisted broadband momentum transformation in optical microresonators

Science.gov (United States)

Jiang, Xuefeng; Shao, Linbo; Zhang, Shu-Xin; Yi, Xu; Wiersig, Jan; Wang, Li; Gong, Qihuang; Lončar, Marko; Yang, Lan; Xiao, Yun-Feng

2017-10-01

The law of momentum conservation rules out many desired processes in optical microresonators. We report broadband momentum transformations of light in asymmetric whispering gallery microresonators. Assisted by chaotic motions, broadband light can travel between optical modes with different angular momenta within a few picoseconds. Efficient coupling from visible to near-infrared bands is demonstrated between a nanowaveguide and whispering gallery modes with quality factors exceeding 10 million. The broadband momentum transformation enhances the device conversion efficiency of the third-harmonic generation by greater than three orders of magnitude over the conventional evanescent-wave coupling. The observed broadband and fast momentum transformation could promote applications such as multicolor lasers, broadband memories, and multiwavelength optical networks.

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.

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

An Assessment of Emerging Wireless Broadband Technologies

National Research Council Canada - National Science Library

Fountanas, Leonidas

2001-01-01

... technologies in providing broadband services today, emerging wireless broadband technologies are expected to significantly increase their market share over the next years, Deploying a wireless network...

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...

Effects of secondary loudspeaker properties on broadband feedforward active duct noise control.

Science.gov (United States)

Chan, Yum-Ji; Huang, Lixi; Lam, James

2013-07-01

Dependence of the performance of feedforward active duct noise control on secondary loudspeaker parameters is investigated. Noise reduction performance can be improved if the force factor of the secondary loudspeaker is higher. For example, broadband noise reduction improvement up to 1.6 dB is predicted by increasing the force factor by 50%. In addition, a secondary loudspeaker with a larger force factor was found to have quicker convergence in the adaptive algorithm in experiment. In simulations, noise reduction is improved in using an adaptive algorithm by using a secondary loudspeaker with a heavier moving mass. It is predicted that an extra broadband noise reduction of more than 7 dB can be gained using an adaptive filter if the force factor, moving mass and coil inductance of a commercially available loudspeaker are doubled. Methods to increase the force factor beyond those of commercially available loudspeakers are proposed.

Broadband infrared absorption enhancement by electroless-deposited silver nanoparticles

DEFF Research Database (Denmark)

Gritti, Claudia; Raza, Søren; Kadkhodazadeh, Shima

2017-01-01

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

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

Fully phase-encoded MRI near metallic implants using ultrashort echo times and broadband excitation.

Science.gov (United States)

Wiens, Curtis N; Artz, Nathan S; Jang, Hyungseok; McMillan, Alan B; Koch, Kevin M; Reeder, Scott B

2018-04-01

To develop a fully phase-encoded MRI method for distortion-free imaging near metallic implants, in clinically feasible acquisition times. An accelerated 3D fully phase-encoded acquisition with broadband excitation and ultrashort echo times is presented, which uses a broadband radiofrequency pulse to excite the entire off-resonance induced by the metallic implant. Furthermore, fully phase-encoded imaging is used to prevent distortions caused by frequency encoding, and to obtain ultrashort echo times for rapidly decaying signal. Phantom and in vivo acquisitions were used to describe the relationship among excitation bandwidth, signal loss near metallic implants, and T 1 weighting. Shorter radiofrequency pulses captured signal closer to the implant by improving spectral coverage and allowing shorter echo times, whereas longer pulses improved T 1 weighting through larger maximum attainable flip angles. Comparisons of fully phase-encoded acquisition with broadband excitation and ultrashort echo times to T 1 -weighted multi-acquisition with variable resonance image combination selective were performed in phantoms and subjects with metallic knee and hip prostheses. These acquisitions had similar contrast and acquisition efficiency. Accelerated fully phase-encoded acquisitions with ultrashort echo times and broadband excitation can generate distortion free images near metallic implants in clinically feasible acquisition times. Magn Reson Med 79:2156-2163, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

CIMEX: a prototype Instrument to observe from space the amazon forest In the near and shortwave infrared

Science.gov (United States)

Guerin, François; Dantes, Didier; Savaria, Eric; Selingardi, Mario Luis; Montes, Amauri Silva

2018-04-01

This paper, "CIMEX: a prototype Instrument to observe from space the amazon forest In the near and shortwave infrared," was presented as part of International Conference on Space Optics—ICSO 1997, held in Toulouse, France.

Chaos-assisted broadband momentum transformation in optical microresonators.

Science.gov (United States)

Jiang, Xuefeng; Shao, Linbo; Zhang, Shu-Xin; Yi, Xu; Wiersig, Jan; Wang, Li; Gong, Qihuang; Lončar, Marko; Yang, Lan; Xiao, Yun-Feng

2017-10-20

The law of momentum conservation rules out many desired processes in optical microresonators. We report broadband momentum transformations of light in asymmetric whispering gallery microresonators. Assisted by chaotic motions, broadband light can travel between optical modes with different angular momenta within a few picoseconds. Efficient coupling from visible to near-infrared bands is demonstrated between a nanowaveguide and whispering gallery modes with quality factors exceeding 10 million. The broadband momentum transformation enhances the device conversion efficiency of the third-harmonic generation by greater than three orders of magnitude over the conventional evanescent-wave coupling. The observed broadband and fast momentum transformation could promote applications such as multicolor lasers, broadband memories, and multiwavelength optical networks. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Integrable discretizations for the short-wave model of the Camassa-Holm equation

International Nuclear Information System (INIS)

Feng Baofeng; Maruno, Ken-ichi; Ohta, Yasuhiro

2010-01-01

The link between the short-wave model of the Camassa-Holm equation (SCHE) and bilinear equations of the two-dimensional Toda lattice equation is clarified. The parametric form of the N-cuspon solution of the SCHE in Casorati determinant is then given. Based on the above finding, integrable semi-discrete and full-discrete analogues of the SCHE are constructed. The determinant solutions of both semi-discrete and fully discrete analogues of the SCHE are also presented.

Broadband availability in metropolitan and non-metropolitan Pennsylvania

Directory of Open Access Journals (Sweden)

Lawrence E. Wood

2016-09-01

Full Text Available Over the past few years having a broadband connection has become essential for many Internet activities. As broadband increases in importance, it becomes imperative to assess how its use and availability may vary, especially in relation to issues such as geographic location. For rural areas in particular, the availability of broadband service is especially important. This research assesses broadband service availability in rural areas of Pennsylvania, USA. In particular, it examines the extent to which Digital Subscriber Line (DSL and broadband cable modem services are being deployed throughout rural Pennsylvania. It compares this deployment with the availability of such services in the state’s urban and metropolitan areas. The results of this research suggest that there is a “digital divide” in terms of broadband availability between rural and urban areas of Pennsylvania. However, this “divide” is perhaps not as wide as might be expected. Thus, as broadband is becoming increasingly available in rural areas of the U.S. and throughout much of the rest of the world, this research concludes that while research must remain vigilant in terms of assessing advanced telecommunications availability in rural areas, future research should also be sure to focus on how such technologies can be used to promote economic and social concerns, including in relation to building online networks and diminishing social and professional isolation in rural areas.

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...

Economists' Statement on U.S. Broadband Policy

OpenAIRE

Kahn, Alfred E.; Goolsbee, Austan; Bailey, Elizabeth E.; Faulhaber, Gerald R.; Mayo, John; Flamm, Kenneth; Baily, Martin Neil; Milgrom, Paul; Cramton, Peter; Gilbert, Richard; Hall, Robert E.; Litan, Robert E.; Hahn, Robert W.; Greenstein, Shane; Hazlett, Thomas W.

2006-01-01

In this statement, a group of economists assembled by the AEI-Brookings Joint Center makes the following two recommendations to improve the competitive provision of broadband services. First, Congress should eliminate local franchising regulations, which serve as a barrier to new entry. Second, Congress and the Federal Communications Commission should make more spectrum available to private parties and allow them to use it as they see fit or trade their licenses in the market, so that spectru...

Femtosecond Broadband Stimulated Raman Spectroscopy

International Nuclear Information System (INIS)

Lee, Soo-Y; Yoon, Sagwoon; Mathies, Richard A

2006-01-01

Femtosecond broadband stimulated Raman spectroscopy (FSRS) is a new technique where a narrow bandwidth picosecond Raman pump pulse and a red-shifted broadband femtosecond Stokes probe pulse (with or without time delay between the pulses) act on a sample to produce a high resolution Raman gain spectrum with high efficiency and speed, free from fluorescence background interference. It can reveal vibrational structural information and dynamics of stationary or transient states. Here, the quantum picture for femtosecond broadband stimulated Raman spectroscopy (FSRS) is used to develop the semiclassical coupled wave theory of the phenomenon and to derive an expression for the measurable Raman gain in FSRS. The semiclassical theory is applied to study the dependence of lineshapes in FSRS on the pump-probe time delay and to deduce vibrational dephasing times in cyclohexane in the ground state

75 FR 10464 - Broadband Technology Opportunities Program

Science.gov (United States)

2010-03-08

... window for Public Computer Center (PCC) and Sustainable Broadband Adoption (SBA) projects. DATES: All...; Extension of Application Closing Deadline for Comprehensive Community Infrastructure (CCI) Projects. SUMMARY... Infrastructure (CCI) projects under the Broadband Technology Opportunities Program (BTOP) is extended until 5:00...

Broadband for all closing the infrastructure gap

CSIR Research Space (South Africa)

Roux, K

2015-10-01

Full Text Available than just addressing the infrastructure issue. The CSIR is mapping the country’s broadband infrastructure to understand where the largest gaps are, is developing models for how those gaps in broadband infrastructure can be closed. In this presentation...

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.

Analytic Approximations for Soliton Solutions of Short-Wave Models for Camassa-Holm and Degasperis-Procesi Equations

International Nuclear Information System (INIS)

Yang Pei; Li Zhibin; Chen Yong

2010-01-01

In this paper, the short-wave model equations are investigated, which are associated with the Camassa-Holm (CH) and Degasperis-Procesi (DP) shallow-water wave equations. Firstly, by means of the transformation of the independent variables and the travelling wave transformation, the partial differential equation is reduced to an ordinary differential equation. Secondly, the equation is solved by homotopy analysis method. Lastly, by the transformations back to the original independent variables, the solution of the original partial differential equation is obtained. The two types of solutions of the short-wave models are obtained in parametric form, one is one-cusp soliton for the CH equation while the other one is one-loop soliton for the DP equation. The approximate analytic solutions expressed by a series of exponential functions agree well with the exact solutions. It demonstrates the validity and great potential of homotopy analysis method for complicated nonlinear solitary wave problems. (general)

Variety identification of brown sugar using short-wave near infrared spectroscopy and multivariate calibration

Science.gov (United States)

Yang, Haiqing; Wu, Di; He, Yong

2007-11-01

Near-infrared spectroscopy (NIRS) with the characteristics of high speed, non-destructiveness, high precision and reliable detection data, etc. is a pollution-free, rapid, quantitative and qualitative analysis method. A new approach for variety discrimination of brown sugars using short-wave NIR spectroscopy (800-1050nm) was developed in this work. The relationship between the absorbance spectra and brown sugar varieties was established. The spectral data were compressed by the principal component analysis (PCA). The resulting features can be visualized in principal component (PC) space, which can lead to discovery of structures correlative with the different class of spectral samples. It appears to provide a reasonable variety clustering of brown sugars. The 2-D PCs plot obtained using the first two PCs can be used for the pattern recognition. Least-squares support vector machines (LS-SVM) was applied to solve the multivariate calibration problems in a relatively fast way. The work has shown that short-wave NIR spectroscopy technique is available for the brand identification of brown sugar, and LS-SVM has the better identification ability than PLS when the calibration set is small.

Broadband adoption, digital divide, and the global economic competitiveness of Western Balkan countries

Directory of Open Access Journals (Sweden)

Mitrović Đorđe

2015-01-01

Full Text Available The existing variation in economic performance between countries is significantly affected by the level, diffusion, and use of different types of information and communication technology. In the last several years economic competitiveness increasingly depends on broadband availability and the adoption, use, and speed of this technology. Broadband access to the internet fosters economic growth and development and increases a country’s global competitiveness. This technology could have a big impact on the competitive advantage of Western Balkan countries because they currently experience a large digital divide, both within countries (between regions, urban and rural areas, different vulnerable groups, etc. and with EU countries. The purpose of the paper is to analyse the current level and dynamics of the digital divide in Western Balkan countries using the Broadband Achievement Index (BAI, the Data Envelopment Analysis (DEA-based model, the Global Competitiveness Index (GCI, the Corruption Perception Index (CPI, and cross-country methodology. This paper measures and compares Western Balkan countries’ current level of broadband adoption and their position on the evolutionary path towards closing the existing economic and digital gap with EU countries. Comparative analysis of calculated BAI data values, GCI, and CPI shows that Western Balkan countries belong to the ‘laggard’ group regarding their broadband achievement and global economic competitiveness. The values of the calculated BAI sub-indexes in this paper indicate the strong and weak sides of the corresponding aspects of broadband technology implementation and give directions for setting further priorities for political intervention, not only in the building of information society but also in the improvement of the economic competitiveness of Western Balkan countries.

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....

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 ...

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.

[Bare Soil Moisture Inversion Model Based on Visible-Shortwave Infrared Reflectance].

Science.gov (United States)

Zheng, Xiao-po; Sun, Yue-jun; Qin, Qi-ming; Ren, Hua-zhong; Gao, Zhong-ling; Wu, Ling; Meng, Qing-ye; Wang, Jin-liang; Wang, Jian-hua

2015-08-01

Soil is the loose solum of land surface that can support plants. It consists of minerals, organics, atmosphere, moisture, microbes, et al. Among its complex compositions, soil moisture varies greatly. Therefore, the fast and accurate inversion of soil moisture by using remote sensing is very crucial. In order to reduce the influence of soil type on the retrieval of soil moisture, this paper proposed a normalized spectral slope and absorption index named NSSAI to estimate soil moisture. The modeling of the new index contains several key steps: Firstly, soil samples with different moisture level were artificially prepared, and soil reflectance spectra was consequently measured using spectroradiometer produced by ASD Company. Secondly, the moisture absorption spectral feature located at shortwave wavelengths and the spectral slope of visible wavelengths were calculated after analyzing the regular spectral feature change patterns of different soil at different moisture conditions. Then advantages of the two features at reducing soil types' effects was synthesized to build the NSSAI. Thirdly, a linear relationship between NSSAI and soil moisture was established. The result showed that NSSAI worked better (correlation coefficient is 0.93) than most of other traditional methods in soil moisture extraction. It can weaken the influences caused by soil types at different moisture levels and improve the bare soil moisture inversion accuracy.

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...

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...

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...

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...

7 CFR 1738.11 - Availability of broadband service.

Science.gov (United States)

2010-01-01

..., DEPARTMENT OF AGRICULTURE RURAL BROADBAND ACCESS LOANS AND LOAN GUARANTEES Loan Purposes and Basic Policies... given to loans to finance service to eligible rural communities in which broadband service is not...

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...

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...

Broadband Liner Optimization for the Source Diagnostic Test Fan

Science.gov (United States)

Nark, Douglas M.; Jones, Michael G.

2012-01-01

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

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.

Satellite observed impacts of wildfires on regional atmosphere composition and shortwave radiative forcing: multiple cases study

Science.gov (United States)

Fu, Y.; Li, R.; Huang, J.; Bergeron, Y.; Fu, Y.

2017-12-01

Emissions of aerosols and trace gases from wildfires and the direct shortwave radiative forcing were studied using multi-satellite/sensor observations from Aqua Moderate-Resolution Imaging Spectroradiometer (MODIS), Aqua Atmospheric Infrared Sounder (AIRS), Aura Ozone Monitoring Instrument (OMI), and Aqua Cloud's and the Earth's Radiant Energy System (CERES). The selected cases occurred in Northeast of China (NEC), Siberia of Russia, California of America have dominant fuel types of cropland, mixed forest and needleleaf forest, respectively. The Fire radiative power (FRP) based emission coefficients (Ce) of aerosol, NOx (NO2+NO), formaldehyde (HCHO), and carbon monoxide (CO) showed significant differences from case to case. 1) the FRP of the cropland case in NEC is strongest, however, the Ce of aerosol is the lowest (20.51 ± 2.55 g MJ-1). The highest Ce of aerosol is 71.34 ± 13.24 g MJ-1 in the needleleaf fire case in California. 2) For NOx, the highest Ce existed in the cropland case in NEC (2.76 ± 0.25 g MJ-1), which is more than three times of those in the forest fires in Siberia and California. 3) The Ce of CO is 70.21±10.97 and 88.38±46.16 g MJ-1 in the forest fires in Western Siberia and California, which are about four times of that in cropland fire. 4) The variation of Ce of HCHO are relatively small among cases. Strong spatial correlations are found among aerosol optical depth (AOD), NOx, HCHO, and CO. The ratios of NOx to AOD, HCHO, and CO in the cropland case in NEC show much higher values than those in other cases. Although huge differences of emissions and composition ratios exist among cases, the direct shortwave (SW) radiative forcing efficiency (SWARFE) of smoke at the top of the atmosphere (TOA) are in good agreement, with the shortwave radiative forcing efficiencies values of 20.09 to 22.93 per unit AOD. Results in this study reveal noteworthy variations of the FRP-based emissions coefficient and relative chemical composition in the smoke

Community Broadband Networks and the Opportunity for E-Government Services

DEFF Research Database (Denmark)

Williams, Idongesit

2017-01-01

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

Semiconductor Quantum Dash Broadband Emitters: Modeling and Experiments

KAUST Repository

Khan, Mohammed Zahed Mustafa

2013-01-01

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

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...

Optimization of an integrated optic broadband duplexer for 0.8/1.3-micrometer applications

Science.gov (United States)

Ghibaudo, Elise; Broquin, Jean-Emmanuel; Benech, Pierre

2003-06-01

These last years, the growth of data traffic has increased the interest for broadband integrated optic devices. Their applications include, for example, the fiber communications on a single fiber by adding the transmission capacity of two optical telecommunication windows for Local Area Networks (LAN) and Wide Area Networks (WAN) or by combining pump and signal wavelenghts in rare earth doped intergrated optical amplifiers. A promising technology to realize those devices is ion-exchange on glass. Indeed, it allows the integration of different functions in a glass substrate with efficient results and a better compatibility in fiber systems with a low cost. We propose in this paper an original broadband duplexer based on a leaky structure. First, the physical principle of the component is explained. The core of the structure is a leaky zone which involves a non-resonant coupling and ensures a broadband spectral behavior to the component. Then, the broadband duplexer is presented and the focus is specially made on the improvement of the outputs crosstalk through the suppression of parasitical back reflections. Theoretical optimization and validation by simulations are presented. Finally, perspectives of this work are proposed.

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.

AIRTV: Broadband Direct to Aircraft

Science.gov (United States)

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

2002-01-01

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

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

The multispectral reflectance of shortwave radiation by agricultural crops in relation with their morphological and optical properties

NARCIS (Netherlands)

Bunnik, N.J.J.

1978-01-01

Relations between morphological properties of uniform canopies. optical properties of the leaves and reflection of shortwave radiation, in the visible light region and the near infrared, by crops are the subject of this thesis.

The aim of the study was a further investigation of

Stationary spectra of short-wave convective and magnetostatic fluctuations in a finite-pressure plasma and anomalous heat conductivity

International Nuclear Information System (INIS)

Vakulenko, M.O.

1992-01-01

Within the general renormalized statistical approach, the low-frequency short-wave stationary spectra of potential and magnetic perturbations in a finite-pressure plasma, are obtained. Anomalous heat conductivity considerably enhances due to non-linear interaction between magnetic excitations. 11 refs. (author)

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.

Bio-inspired heterogeneous composites for broadband vibration mitigation.

Science.gov (United States)

Chen, Yanyu; Wang, Lifeng

2015-12-08

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.

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.

Impacts of spectral nudging on the simulated surface air temperature in summer compared with the selection of shortwave radiation and land surface model physics parameterization in a high-resolution regional atmospheric model

Science.gov (United States)

Park, Jun; Hwang, Seung-On

2017-11-01

The impact of a spectral nudging technique for the dynamical downscaling of the summer surface air temperature in a high-resolution regional atmospheric model is assessed. The performance of this technique is measured by comparing 16 analysis-driven simulation sets of physical parameterization combinations of two shortwave radiation and four land surface model schemes of the model, which are known to be crucial for the simulation of the surface air temperature. It is found that the application of spectral nudging to the outermost domain has a greater impact on the regional climate than any combination of shortwave radiation and land surface model physics schemes. The optimal choice of two model physics parameterizations is helpful for obtaining more realistic spatiotemporal distributions of land surface variables such as the surface air temperature, precipitation, and surface fluxes. However, employing spectral nudging adds more value to the results; the improvement is greater than using sophisticated shortwave radiation and land surface model physical parameterizations. This result indicates that spectral nudging applied to the outermost domain provides a more accurate lateral boundary condition to the innermost domain when forced by analysis data by securing the consistency with large-scale forcing over a regional domain. This consequently indirectly helps two physical parameterizations to produce small-scale features closer to the observed values, leading to a better representation of the surface air temperature in a high-resolution downscaled climate.

Contrails and their impact on shortwave radiation and photovoltaic power production – a regional model study

Directory of Open Access Journals (Sweden)

S. Gruber

2018-05-01

Full Text Available A high-resolution regional-scale numerical model was extended by a parameterization that allows for both the generation and the life cycle of contrails and contrail cirrus to be calculated. The life cycle of contrails and contrail cirrus is described by a two-moment cloud microphysical scheme that was extended by a separate contrail ice class for a better representation of the high concentration of small ice crystals that occur in contrails. The basic input data set contains the spatially and temporally highly resolved flight trajectories over Central Europe derived from real-time data. The parameterization provides aircraft-dependent source terms for contrail ice mass and number. A case study was performed to investigate the influence of contrails and contrail cirrus on the shortwave radiative fluxes at the earth's surface. Accounting for contrails produced by aircraft enabled the model to simulate high clouds that were otherwise missing on this day. The effect of these extra clouds was to reduce the incoming shortwave radiation at the surface as well as the production of photovoltaic power by up to 10 %.

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)

Observations involving broadband impedance modelling

International Nuclear Information System (INIS)

Berg, J.S.

1995-08-01

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

Decadal changes in shortwave irradiance at the surface in the period from 1960 to 2000 estimated from Global Energy Balance Archive Data

Science.gov (United States)

Gilgen, H.; Roesch, A.; Wild, M.; Ohmura, A.

2009-05-01

Decadal changes in shortwave irradiance at the Earth's surface are estimated for the period from approximately 1960 through to 2000 from pyranometer records stored in the Global Energy Balance Archive. For this observational period, estimates could be calculated for a total of 140 cells of the International Satellite Cloud Climatology Project grid (an equal area 2.5° × 2.5° grid at the equator) using regression models allowing for station effects. In large regions worldwide, shortwave irradiance decreases in the first half of the observational period, recovers from the decrease in the 1980s, and thereafter increases, in line with previous reports. Years of trend reversals are determined for the grid cells which are best described with a second-order polynomial model. This reversal of the trend is observed in the majority of the grid cells in the interior of Europe and in Japan. In China, shortwave irradiance recovers during the 1990s in the majority of the grid cells in the southeast and northeast from the decrease observed in the period from 1960 through to 1990. A reversal of the trend in the 1980s or early 1990s is also observed for two grid cells in North America, and for the grid cells containing the Kuala Lumpur (Malaysia), Singapore, Casablanca (Morocco), Valparaiso (Chile) sites, and, noticeably, the remote South Pole and American Samoa sites. Negative trends persist, i.e., shortwave radiation decreases, for the observational period 1960 through to 2000 at the European coasts, in central and northwest China, and for three grid cells in India and two in Africa.

Does shortwave absorption by methane influence its effectiveness?

Science.gov (United States)

Modak, Angshuman; Bala, Govindasamy; Caldeira, Ken; Cao, Long

2018-01-01

In this study, using idealized step-forcing simulations, we examine the effective radiative forcing of CH4 relative to that of CO2 and compare the effects of CH4 and CO2 forcing on the climate system. A tenfold increase in CH4 concentration in the NCAR CAM5 climate model produces similar long term global mean surface warming ( 1.7 K) as a one-third increase in CO2 concentration. However, the radiative forcing estimated for CO2 using the prescribed-SST method is 81% that of CH4, indicating that the efficacy of CH4 forcing is 0.81. This estimate is nearly unchanged when the CO2 physiological effect is included in our simulations. Further, for the same long-term global mean surface warming, we simulate a smaller precipitation increase in the CH4 case compared to the CO2 case. This is because of the fast adjustment processes—precipitation reduction in the CH4 case is larger than that of the CO2 case. This is associated with a relatively more stable atmosphere and larger atmospheric radiative forcing in the CH4 case which occurs because of near-infrared absorption by CH4 in the upper troposphere and lower stratosphere. Within a month after an increase in CH4, this shortwave heating results in a temperature increase of 0.8 K in the lower stratosphere and upper troposphere. In contrast, within a month after a CO2 increase, longwave cooling results in a temperature decrease of 3 K in the stratosphere and a small change in the upper troposphere. These fast adjustments in the lower stratospheric and upper tropospheric temperature, along with the adjustments in clouds in the troposphere, influence the effective radiative forcing and the fast precipitation response. These differences in fast climate adjustments also produce differences in the climate states from which the slow response begins to evolve and hence they are likely associated with differing feedbacks. We also find that the tropics and subtropics are relatively warmer in the CH4 case for the same global mean

The promise of downlink MU-MIMO for high-capacity next generation mobile broadband networks based on IEEE 802.16 m

Directory of Open Access Journals (Sweden)

Papathanassiou Apostolos

2011-01-01

Full Text Available Abstract The dramatic increase of the demand for mobile broadband services poses stringent requirements on the performance evolution of currently deployed mobile broadband networks, such as Mobile WiMAX Release 1 and 3GPP LTE Release 8. Although the combination of single-user multiple-input multiple-output (SU-MIMO and orthogonal frequency division multiple access (OFDMA provide the appropriate technologies for improving the downlink performance of third generation (3G code division multiple access (CDMA-based mobile radio systems and, thus, address the current mobile internet requirements, a fundamental paradigm shift is required to cope with the constantly increasing mobile broadband data rate and spectral efficiency requirements. Among the different technologies available for making the paradigm shift from current to next-generation mobile broadband networks, multiuser MIMO (MU-MIMO constitutes the most promising technology because of its significant performance improvement advantages. In this article, we analyze the performance of MU-MIMO under a multitude of deployment scenarios and system parameters through extensive system-level simulations which are based on widely used system-level evaluation methodologies. The target mobile broadband system used in the simulations is IEEE 802.16 m which was recently adopted by ITU-R as an IMT-Advanced technology along with 3GPP LTE-Advanced. The results provide insights into different aspects of MU-MIMO with respect to system-level performance, parameter sensitivity, and deployment scenarios, and they can be used by the mobile broadband network designer for maximizing the benefits of MU-MIMO in a scenario with specific deployment requirements and goals.

A Discourse On Broadband Technologies And Curriculum Access In Elective Home Learning

Directory of Open Access Journals (Sweden)

Andrew MCAVOY

2014-12-01

Full Text Available The extent, to which broadband technologies are being considered, when accessing the curriculum, is increasingly evident in traditional learning environments such as schools and colleges. This article explores the impact that these technologies are having on the home schooling community by offering enhanced access and opportunities. It suggests that they have generated improved choices and greater freedoms for learning communities. They have shone a light on the curriculum and removed it from the shadows. The curriculum is no longer the preserve of the educational establishment. The secret garden has been breached by technologies such as broadband and the democratisation of the curriculum is progressively evident as more diverse learning communities are given increased access and control over the curriculum. The author asks how this is being reflected in policy and translated into practice by the home schooling community whilst acknowledging the contemporary nature of broadband technologies and how they are influencing the decision making process of potential home schoolers. Looking to the future, the author suggests that the political agenda is not providing clear direction and that this is being determined by social reform outside the political sphere and largely driven by the consumer. In this case the learner. The relatively current nature of this debate is in itself justification for further research if we are to develop a clearer understanding of how new technologies such as broadband are influencing policy and practice in the home schooling community.

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...

Tunable Broadband Nanocarbon Transparent Conductor by Electrochemical Intercalation.

Science.gov (United States)

Wan, Jiayu; Xu, Yue; Ozdemir, Burak; Xu, Lisha; Sushkov, Andrei B; Yang, Zhi; Yang, Bao; Drew, Dennis; Barone, Veronica; Hu, Liangbing

2017-01-24

Optical transparent and electrical conducting materials with broadband transmission are important for many applications in optoelectronic, telecommunications, and military devices. However, studies of broadband transparent conductors and their controlled modulation are scarce. In this study, we report that reversible transmittance modulation has been achieved with sandwiched nanocarbon thin films (containing carbon nanotubes (CNTs) and reduced graphene oxide (rGO)) via electrochemical alkali-ion intercalation/deintercalation. The transmittance modulation covers a broad range from the visible (450 nm) to the infrared (5 μm), which can be achieved only by rGO rather than pristine graphene films. The large broadband transmittance modulation is understood with DFT calculations, which suggest a decrease in interband transitions in the visible range as well as a reduced reflection in the IR range upon intercalation. We find that a larger interlayer distance in few-layer rGO results in a significant increase in transparency in the infrared region of the spectrum, in agreement with experimental results. Furthermore, a reduced plasma frequency in rGO compared to few-layer graphene is also important to understand the experimental results for broadband transparency in rGO. The broadband transmittance modulation of the CNT/rGO/CNT systems can potentially lead to electrochromic and thermal camouflage applications.

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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

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

Science.gov (United States)

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

2014-12-01

against GMPEs, and several new data products, such as map and distance-based goodness of fit plots. As the number and complexity of scenarios simulated using the Broadband Platform increases, we have added batching utilities to substantially improve support for running large-scale simulations on computing clusters.

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

Science.gov (United States)

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

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

Optimizing UV Index determination from broadband irradiances

Science.gov (United States)

Tereszchuk, Keith A.; Rochon, Yves J.; McLinden, Chris A.; Vaillancourt, Paul A.

2018-03-01

A study was undertaken to improve upon the prognosticative capability of Environment and Climate Change Canada's (ECCC) UV Index forecast model. An aspect of that work, and the topic of this communication, was to investigate the use of the four UV broadband surface irradiance fields generated by ECCC's Global Environmental Multiscale (GEM) numerical prediction model to determine the UV Index. The basis of the investigation involves the creation of a suite of routines which employ high-spectral-resolution radiative transfer code developed to calculate UV Index fields from GEM forecasts. These routines employ a modified version of the Cloud-J v7.4 radiative transfer model, which integrates GEM output to produce high-spectral-resolution surface irradiance fields. The output generated using the high-resolution radiative transfer code served to verify and calibrate GEM broadband surface irradiances under clear-sky conditions and their use in providing the UV Index. A subsequent comparison of irradiances and UV Index under cloudy conditions was also performed. Linear correlation agreement of surface irradiances from the two models for each of the two higher UV bands covering 310.70-330.0 and 330.03-400.00 nm is typically greater than 95 % for clear-sky conditions with associated root-mean-square relative errors of 6.4 and 4.0 %. However, underestimations of clear-sky GEM irradiances were found on the order of ˜ 30-50 % for the 294.12-310.70 nm band and by a factor of ˜ 30 for the 280.11-294.12 nm band. This underestimation can be significant for UV Index determination but would not impact weather forecasting. Corresponding empirical adjustments were applied to the broadband irradiances now giving a correlation coefficient of unity. From these, a least-squares fitting was derived for the calculation of the UV Index. The resultant differences in UV indices from the high-spectral-resolution irradiances and the resultant GEM broadband irradiances are typically within 0

The U.S. Market For Broadband Over Powerline, 3. edition

Energy Technology Data Exchange (ETDEWEB)

NONE

2007-07-15

The report provides a study of the potential market for BPL technology in the U.S. including a look at the past, present, and future state of Broadband Over Powerline (BPL) in the U.S. The Scope of the report includes the following topics: a description of the history of powerline communications (PLC) and broadband over powerline (BPL) technology; an analysis of key drivers of BPL within the electric utility and internet access industries; an overview of BPL technology and architecture; a comparison of BPL with alternative broadband access methods; an analysis of technological, regulatory, and business barriers to BPL's success; identification of the key applications and markets for BPL; a description of business models for BPL; an analysis of key market trends in broadband internet access; a review of the market development of cable modem broadband access; profiles of major U.S. BPL market participants; and, profiles of major U.S. BPL projects.

Direct shortwave forcing of climate by anthropogenic sulfate aerosol: Sensitivity to particle size, composition, and relative humidity

Energy Technology Data Exchange (ETDEWEB)

Nemesure, S.; Wagener, R.; Schwartz, S.E. [Brookhaven National Lab., Upton, New York (United States)

1996-04-01

Recent estimates of global or hemispheric average forcing of climate by anthropogenic sulfate aerosol due to scattering of shortwave radiation are uncertain by more than a factor of 2. This paper examines the sensitivity of forcing to these microphysical properties for the purposes of obtaining a better understanding of the properties required to reduce the uncertainty in the forcing.

Visible light broadband perfect absorbers

Energy Technology Data Exchange (ETDEWEB)

Jia, X. L.; Meng, Q. X.; Yuan, C. X.; Zhou, Z. X.; Wang, X. O., E-mail: wxo@hit.edu.cn [School of Science, Harbin Institute of Technology, Harbin 150001 (China)

2016-03-15

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

Broadband waveguided light sources

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

Policy factors affecting broadband development in Poland

DEFF Research Database (Denmark)

Henten, Anders; Windekilde, Iwona Maria

2014-01-01

of telecommunications network development in Poland than other countries in the European Union is the reason that the circumstances and also the effects of the implementation of some solutions of the EU regulation model are different in Poland than in the most developed EU countries. The aim of the paper is to examine...... 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....../distribution in the country and the infrastructural point of departure. The paper, therefore, analyses the implications of the policy initiatives in light of these basic conditions and the broader context of factors influencing broadband development. In the paper, different kinds of policy initiatives are examined...

Broadband manipulation of refracted wavefronts by gradient acoustic metasurface with V-shape structure

Science.gov (United States)

Lan, Jun; Li, Yifeng; Liu, Xiaozhou

2017-12-01

We present a space folding acoustic metasurface with a V-shaped structure, which exhibits ultra-broadband and high efficiency transmission compared to previously investigated space folding metasurfaces. The proposal employs a gradient refractive index profile to redirect the refracted wave arbitrarily and an existence of air channels with direct sound propagation to improve impedance matching between the metasurface and the background medium. As expected from frequency-independent generalized Snell's law, the demonstrated acoustic metasurface can steer refracted wavefronts at will, including anomalous refraction, non-diffracting Bessel beam, sub-wavelength flat lens, and conversion of the propagating wave into the surface wave. The designed V-shape metasurface overcomes the limitation of narrowband, which may offer potential applications in medical ultrasound imaging and broadband acoustical devices.

Radiometer Calibration and Characterization (RCC) User's Manual: Windows Version 4.0

Energy Technology Data Exchange (ETDEWEB)

Andreas, Afshin M. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Wilcox, Stephen M. [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2016-02-29

The Radiometer Calibration and Characterization (RCC) software is a data acquisition and data archival system for performing Broadband Outdoor Radiometer Calibrations (BORCAL). RCC provides a unique method of calibrating broadband atmospheric longwave and solar shortwave radiometers using techniques that reduce measurement uncertainty and better characterize a radiometer's response profile. The RCC software automatically monitors and controls many of the components that contribute to uncertainty in an instrument's responsivity. This is a user's manual and guide to the RCC software.

Optical broadband in-home networks for converged service delivery

NARCIS (Netherlands)

Shi, Y.

2013-01-01

Broadband access networks, and in particular fibre-to-the-home (FTTH) networks, are offering abundantly available bandwidth in the local loop with high quality of services. Under such broadband connectivity conditions, in-home networks should not represent the bottleneck for high capacity service

A practical approach to compute short-wave irradiance interacting with subgrid-scale buildings

Energy Technology Data Exchange (ETDEWEB)

Sievers, Uwe; Frueh, Barbara [Deutscher Wetterdienst, Offenbach am Main (Germany)

2012-08-15

A numerical approach for the calculation of short-wave irradiances at the ground as well as the walls and roofs of buildings in an environment with unresolved built-up is presented. In this radiative parameterization scheme the properties of the unresolved built-up are assigned to settlement types which are characterized by mean values of the volume density of the buildings and their wall area density. Therefore it is named wall area approach. In the vertical direction the range of building heights may be subdivided into several layers. In the case of non-uniform building heights the shadowing of the lower roofs by the taller buildings is taken into account. The method includes the approximate calculation of sky view and sun view factors. For an idealized building arrangement it is shown that the obtained approximate factors are in good agreement with exact calculations just as for the comparison of the calculated and measured effective albedo values. For arrangements with isolated single buildings the presented wall area approach yields a better agreement with the observations than similar methods where the unresolved built-up is characterized by the aspect ratio of a representative street canyon (aspect ratio approach). In the limiting case where the built-up is well represented by an ensemble of idealized street canyons both approaches become equivalent. The presented short-wave radiation scheme is part of the microscale atmospheric model MUKLIMO 3 where it contributes to the calculation of surface temperatures on the basis of energy-flux equilibrium conditions. (orig.)

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.

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...

Direct and quantitative broadband absorptance spectroscopy with multilayer cantilever probes

Science.gov (United States)

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

2015-04-21

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

Atlantic bottlenose dolphin (Tursiops truncatus) hearing threshold for brief broadband signals.

Science.gov (United States)

Au, Whitlow W L; Lemonds, David W; Vlachos, Stephanie; Nachtigall, Paul E; Roitblat, Herbert L

2002-06-01

The hearing sensitivity of an Atlantic bottlenose dolphin (Tursiops truncatus) to both pure tones and broadband signals simulating echoes from a 7.62-cm water-filled sphere was measured. Pure tones with frequencies between 40 and 140 kHz in increments of 20 kHz were measured along with broadband thresholds using a stimulus with a center frequency of 97.3 kHz and 88.2 kHz. The pure-tone thresholds were compared with the broadband thresholds by converting the pure-tone threshold intensity to energy flux density. The results indicated that dolphins can detect broadband signals slightly better than a pure-tone signal. The broadband results suggest that an echolocating bottlenose dolphin should be able to detect a 7.62-cm diameter water-filled sphere out to a range of 178 m in a quiet environment.

Broadband and Unbundling Regulations in OECD Countries

OpenAIRE

Wallsten, Scott

2006-01-01

Broadband penetration and available speeds vary widely across OECD countries. Policymakers around the world, and especially in countries like the U.S. that lag in the rankings, are searching for policies to narrow those gaps. Relatively little empirical work tests possible reasons for these differences. In this paper I test the impacts of regulations and demographics on broadband development in a panel dataset across countries. In addition to adding to the meager empirical literature on broad...

Radio-over-fibre technology for broadband wireless communication systems

NARCIS (Netherlands)

Ng'Oma, A.

2005-01-01

Wireless coverage of the end-user domain, be it outdoors or indoors (in-building), is poised to become an essential part of broadband communication networks. In order to offer integrated broadband services (combining voice, data, video, multimedia services, and new value added services), these

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...

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...

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...

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...

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...

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...

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...

Spatial-temporal dynamics of broadband terahertz Bessel beam propagation

International Nuclear Information System (INIS)

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

2016-01-01

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

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.

EVALUASI LAYANAN BROADBAND CAMPUS DENGAN MENGGUNAKAN FRAMEWORK COBIT 4.1

Directory of Open Access Journals (Sweden)

Fajar Tri Prabowo

2017-08-01

Full Text Available Abstract - Broadband campus is a high speed internet service with high transfer rate that implemented within the campus area. The sole purpose of this service is to optimize the internet network in certain area that is still lack of a high speed internet connection. This paper will ellaborate more on the evaluation of certain ongoing broadband campus service at Mahasaraswati University in Denpasar by using COBIT 4.1 Framework. This evaluation is intended to enhance the user effectiveness through existing services. This evaluation was conducted through certain mini-survey by using the broadband campus IT service by examining the university students satisfaction through series of interviews and questionnaires. The conclusion that was inferred through the surveys is that the broadband services within the university gain a subsequently low existing maturity level with 1.9 mark in the COBIT Framework scale. One of the major reason of why the service acquire low satisfaction level within the university is due the students in Mahasaraswati University did not manage to optimize the broadband campus service in the first place

The promise of downlink MU-MIMO for high-capacity next generation mobile broadband networks based on IEEE 802.16 m

OpenAIRE

Papathanassiou Apostolos; Davydov Alexei

2011-01-01

Abstract The dramatic increase of the demand for mobile broadband services poses stringent requirements on the performance evolution of currently deployed mobile broadband networks, such as Mobile WiMAX Release 1 and 3GPP LTE Release 8. Although the combination of single-user multiple-input multiple-output (SU-MIMO) and orthogonal frequency division multiple access (OFDMA) provide the appropriate technologies for improving the downlink performance of third generation (3G) code division multip...

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.

A novel method for surface defect inspection of optic cable with short-wave infrared illuminance

Science.gov (United States)

Chen, Xiaohong; Liu, Ning; You, Bo; Xiao, Bin

2016-07-01

Intelligent on-line detection of cable quality is a crucial issue in optic cable factory, and defects on the surface of optic cable can dramatically depress cable grade. Manual inspection in optic cable quality cannot catch up with the development of optic cable industry due to its low detection efficiency and huge human cost. Therefore, real-time is highly demanded by industry in order to replace the subjective and repetitive process of manual inspection. For this reason, automatic cable defect inspection has been a trend. In this paper, a novel method for surface defect inspection of optic cable with short-wave infrared illuminance is presented. The special condition of short-wave infrared cannot only provide illumination compensation for the weak illumination environment, but also can avoid the problem of exposure when using visible light illuminance, which affects the accuracy of inspection algorithm. A series of image processing algorithms are set up to analyze cable image for the verification of real-time and veracity of the detection method. Unlike some existing detection algorithms which concentrate on the characteristics of defects with an active search way, the proposed method removes the non-defective areas of the image passively at the same time of image processing, which reduces a large amount of computation. OTSU algorithm is used to convert the gray image to the binary image. Furthermore, a threshold window is designed to eliminate the fake defects, and the threshold represents the considered minimum size of defects ε . Besides, a new regional suppression method is proposed to deal with the edge burrs of the cable, which shows the superior performance compared with that of Open-Close operation of mathematical morphological in the boundary processing. Experimental results of 10,000 samples show that the rates of miss detection and false detection are 2.35% and 0.78% respectively when ε equals to 0.5 mm, and the average processing period of one frame

The Validation of the GEWEX SRB Surface Shortwave Flux Data Products Using BSRN Measurements: A Systematic Quality Control, Production and Application Approach

Science.gov (United States)

Zhang, Taiping; Stackhouse, Paul W., Jr.; Gupta, Shashi K.; Cox, Stephen J.; Mikovitz, J. Colleen; Hinkelman, Laura M.

2013-01-01

The NASA/GEWEX Surface Radiation Budget (SRB) project has produced a 24.5-year continuous record of global shortwave and longwave radiation fluxes at TOA and the Earth's surface from satellite measurements. The time span of the data is from July 1983 to December 2007, and the spatial resolution is 11 latitude11 longitude. The inputs of the latest version (Release 3.0) include the GEOS Version 4.0.3 meteorological information and cloud properties derived from ISCCP DX data. The SRB products are available on 3-hourly, 3-hourly-monthly, daily and monthly time scales. To assess the quality of the product, we extensively validated the SRB data against 5969 site-months of groundbased measurements from 52 Baseline Surface Radiation Network (BSRN) stations. This paper describes first the characteristics of the BSRN data and the GEWEX SRB data, the methodology for quality control and processing of the shortwave BSRN data, and then the systematic SRB-BSRN comparisons. It is found that, except for occasional extreme outliers as seen in scatter plots, the satellite-based surface radiation data generally agree very well with BSRN measurements. Specifically, the bias/RMS for the daily and monthly mean shortwave fluxes are, respectively, -3.6/35.5 and -5.2/23.3W1 m2 under all-sky conditions.

Magnetically levitated autoparametric broadband vibration energy harvesting

International Nuclear Information System (INIS)

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

2016-01-01

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

Silicon graphene waveguide tunable broadband microwave photonics phase shifter.

Science.gov (United States)

Capmany, José; Domenech, David; Muñoz, Pascual

2014-04-07

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

National Broadband strategies – The case of Brazil

DEFF Research Database (Denmark)

Falch, Morten; Iaskio, Emerson

2018-01-01

as differences in institutional factors. For instance has the government played a leading role in Japan and South Korea, while US and UK have a strong emphasis on market forces and competition. Brazil has chosen their own strategy for broadband development. This strategy is defined within a specific national...... of comparing broadband strategies in different countries. The paper first describes these dimensions, and how the framework relates to other kinds of categorisations. Second it provides a brief overview of how the Brazilian telecom market developed. The subsequent section presents various policy initiatives......). Broadband for all is a widely accepted policy objective in both developed and developing countries. However, the policy strategies for achieving this goal are very different in different countries. These differences are originated in different levels of economic and technological development, as well...

System and method for detection of dispersed broadband signals

Science.gov (United States)

Qian, S.; Dunham, M.E.

1999-06-08

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

Detailed Balance Limit of Efficiency of Broadband-Pumped Lasers.

Science.gov (United States)

Nechayev, Sergey; Rotschild, Carmel

2017-09-13

Broadband light sources are a wide class of pumping schemes for lasers including LEDs, sunlight and flash lamps. Recently, efficient coupling of broadband light to high-quality micro-cavities has been demonstrated for on-chip applications and low-threshold solar-pumped lasers via cascade energy transfer. However, the conversion of incoherent to coherent light comes with an inherent price of reduced efficiency, which has yet to be assessed. In this paper, we derive the detailed balance limit of efficiency of broadband-pumped lasers and discuss how it is affected by the need to maintain a threshold population inversion and thermodynamically dictated minimal Stokes' shift. We show that lasers' slope efficiency is analogous to the nominal efficiency of solar cells, limited by thermalisation losses and additional unavoidable Stokes' shift. The lasers' power efficiency is analogous to the detailed balance limit of efficiency of solar cells, affected by the cavity mirrors and impedance matching factor, respectively. As an example we analyze the specific case of solar-pumped sensitized Nd 3+ :YAG-like lasers and define the conditions to reach their thermodynamic limit of efficiency. Our work establishes an upper theoretical limit for the efficiency of broadband-pumped lasers. Our general, yet flexible model also provides a way to incorporate other optical and thermodynamic losses and, hence, to estimate the efficiency of non-ideal broadband-pumped lasers.

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.

Participation in the broadband society in Denmark

DEFF Research Database (Denmark)

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

2009-01-01

passed the threshold set by the EU with respect to the relevance of initiating a discussion on the implementation of a universal service obligation on broadband. As documented in the paper, there are groups among primarily the elderly and the unemployed who do not have Internet access. Their own......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...

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...

Organic, cross-linking, and shape-stabilized solar thermal energy storage materials: A reversible phase transition driven by broadband visible light

International Nuclear Information System (INIS)

Wang, Yunming; Tang, Bingtao; Zhang, Shufen

2014-01-01

Graphical abstract: Organic shape-stabilized solar thermal energy storage materials (OCSPCMs) with broadband harvesting for visible light were obtained by crosslinking and color matching, which provided a new platform for improving the efficiency of solar radiation utilization. - Highlights: • Novel phase change materials (OCSPCMs) were obtained by crosslinking and color matching. • The η of the OCSPCM was higher than 0.74 (visible light from 400 nm to 700 nm). • The phase change latent heats of the OCSPCMs were more than 120 J/g. • The OCSPCM has excellent form-stable effect during phase change process. - Abstract: Broadband visible sunlight usage and shape-stabilized effect were achieved using organic, cross-linking, and shape-stabilized phase-changed materials (OCSPCMs) with broadband visible light absorption, which were obtained by cross-linking reticulation and color matching (yellow, red, and blue) according to solar irradiation energy density. The obtained OCSPCMs exhibited excellent form-stable phase-change energy storage and broadband visible light-harvesting. Under broadband irradiation (from 400 nm to 700 nm), the light-to-heat conversion and the thermal energy storage efficiency (η > 0.74) of the OCSPCMs were significantly improved upon solar irradiation by color matching compared with those of OCSPCMs with single-band selective absorption of visible light (yellow, red, or blue). Differential scanning calorimetric results indicated that the phase change temperatures and latent heats of OCSPCMs ranged from 32.6 °C to 60.2 °C and from 120.1 J/g to 132.7 J/g, respectively. The novel materials show a reversible (more than 200 cycles) phase transition via ON/OFF switching of visible light irradiation

Effect of surface albedo, water vapour, and atmospheric aerosols on the cloud-free shortwave radiative budget in the Arctic

Energy Technology Data Exchange (ETDEWEB)

Di Biagio, C. [ENEA, Laboratory for Earth Observations and Analyses, Rome (Italy); University of Siena, Department of Earth Science, Siena (Italy); Di Sarra, A. [ENEA, Laboratory for Earth Observations and Analyses, Rome (Italy); Eriksen, P. [Danish Climate Centre, DMI, Danish Meteorological Institute, Copenhagen (Denmark); Ascanius, S.E. [DMI, Danish Meteorological Institute, Qaanaaq (Greenland); Muscari, G. [INGV, Istituto Nazionale di Geofisica e Vulcanologia, Rome (Italy); Holben, B. [NASA Goddard Space Flight Center, Greenbelt, MD (United States)

2012-08-15

This study is based on ground-based measurements of downward surface shortwave irradiance (SW), columnar water vapour (wv), and aerosol optical depth ({tau}) obtained at Thule Air Base (Greenland) in 2007-2010, together with MODIS observations of the surface shortwave albedo (A). Radiative transfer model calculations are used in combination with measurements to separate the radiative effect of A ({Delta}SW{sub A}), wv ({Delta}SW{sub wv}), and aerosols ({Delta}SW{sub {tau}}) in modulating SW in cloud-free conditions. The shortwave radiation at the surface is mainly affected by water vapour absorption, which produces a reduction of SW as low as -100 Wm{sup -2} (-18%). The seasonal change of A produces an increase of SW by up to +25 Wm{sup -2} (+4.5%). The annual mean radiative effect is estimated to be -(21-22) Wm{sup -2} for wv, and +(2-3) Wm{sup -2} for A. An increase by +0.065 cm in the annual mean wv, to which corresponds an absolute increase in {Delta}SW{sub wv} by 0.93 Wm{sup -2} (4.3%), has been observed to occur between 2007 and 2010. In the same period, the annual mean A has decreased by -0.027, with a corresponding decrease in {Delta}SW{sub A} by 0.41 Wm{sup -2} (-14.9%). Atmospheric aerosols produce a reduction of SW as low as -32 Wm{sup -2} (-6.7%). The instantaneous aerosol radiative forcing (RF{sub {tau}}) reaches values of -28 Wm{sup -2} and shows a strong dependency on surface albedo. The derived radiative forcing efficiency (FE{sub {tau}}) for solar zenith angles between 55 and 70 is estimated to be (-120.6 {+-} 4.3) for 0.1 < A < 0.2, and (-41.2 {+-} 1.6) Wm{sup -2} for 0.5 < A < 0.6. (orig.)

A Design of 45-Degree Dual-Polarization Broadband Plane Station Antenna

Directory of Open Access Journals (Sweden)

Jianming Zhou

2015-01-01

Full Text Available A new broadband planar dual-polarization base station antenna is proposed, the antenna consists of two broadband plane coplanar base station antenna units, and so it has features of plane antenna. Two broadband plane station antenna units can, respectively, form double polarization in the direction. We analyzed the relative positions between the two antenna units and their effects on the performances of the antenna, especially for the influence of isolation. Broadband antenna has the characteristics of the broadband station antenna, and bandwidth is also guaranteed. The measured results show that the antenna can obtain 45% relative bandwidth, and 30 dB isolation degree also can be got, and the radiation performance is also good. Measurement results confirmed that the antenna gain can be guaranteed among 48% relative bandwidth, 15 dB of gain is got among bandwidth of 1.69–2.78 GHz, the isolation degree of different polarization method can reach 30 dB, and the measurement gain of two polarization methods of antenna both can reach 8.5 dBi.

Design of broadband single polarized antenna

Science.gov (United States)

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

2015-05-01

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

Application of Improved Radiation Modeling to General Circulation Models

Energy Technology Data Exchange (ETDEWEB)

Michael J Iacono

2011-04-07

This research has accomplished its primary objectives of developing accurate and efficient radiation codes, validating them with measurements and higher resolution models, and providing these advancements to the global modeling community to enhance the treatment of cloud and radiative processes in weather and climate prediction models. A critical component of this research has been the development of the longwave and shortwave broadband radiative transfer code for general circulation model (GCM) applications, RRTMG, which is based on the single-column reference code, RRTM, also developed at AER. RRTMG is a rigorously tested radiation model that retains a considerable level of accuracy relative to higher resolution models and measurements despite the performance enhancements that have made it possible to apply this radiation code successfully to global dynamical models. This model includes the radiative effects of all significant atmospheric gases, and it treats the absorption and scattering from liquid and ice clouds and aerosols. RRTMG also includes a statistical technique for representing small-scale cloud variability, such as cloud fraction and the vertical overlap of clouds, which has been shown to improve cloud radiative forcing in global models. This development approach has provided a direct link from observations to the enhanced radiative transfer provided by RRTMG for application to GCMs. Recent comparison of existing climate model radiation codes with high resolution models has documented the improved radiative forcing capability provided by RRTMG, especially at the surface, relative to other GCM radiation models. Due to its high accuracy, its connection to observations, and its computational efficiency, RRTMG has been implemented operationally in many national and international dynamical models to provide validated radiative transfer for improving weather forecasts and enhancing the prediction of global climate change.

Broadband manipulation of acoustic wavefronts by pentamode metasurface

International Nuclear Information System (INIS)

Tian, Ye; Wei, Qi; Cheng, Ying; Xu, Zheng; Liu, Xiaojun

2015-01-01

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

Prediction of broadband trailing edge noise from a NACA0012 airfoil using wall-modeled large-eddy simulation

Science.gov (United States)

Mehrabadi, Mohammad; Bodony, Daniel

2017-11-01

In modern high-bypass ratio turbofan engines, the reduction of jet exhaust noise through engine design has increased the acoustic importance of the main fan to the point where it can be the primary source of noise in the fight direction of an airplane. While fan noise has been reduced by improved fan designs, its broadband component, originating from the interaction of turbulent flow with a solid surface, still remains an issue. Broadband fan noise is generated by several mechanisms, usually involving a turbulent boundary layer interacting with a solid surface. To prepare for a wall modeled large eddy simulation (WMLES) of the NASA/GE source diagnostic test fan, we study the broadband noise due to the turbulent flow on a NACA0012 airfoil at zero degree angle-of-attack, a chord-based Reynolds number of 408,000, and a Mach number of 0.115 using WMLES. We investigate the prediction of transition-to-turbulence and sound generation from the WMLES and examine its predictability compared with available experimental and DNS datasets for the same flow conditions. Verification of WMLES for such a canonical problem is crucial since it provides useful insight about the WMLES approach before using it for broadband fan noise prediction. AeroAcoustics Research Consortium.

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

International Nuclear Information System (INIS)

Li, Xiaoyu; He, Junhui; Liu, Weiyi

2013-01-01

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

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

Science.gov (United States)

Morin, Bruce L.

2010-01-01

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

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 of th...

A broadband electromagnetic UT system

International Nuclear Information System (INIS)

Repplinger, W.; Salzburger, H.J.

1985-01-01

An ultrasonic testing system based on contactless electromagnetic acoustic (E.M.A.) transduction has been developed by which broadband ultrasonic pulses are excited. This system overcomes disadvantages of usual E.M.A. transducers with meanderlike coil configuration, namely the excitation of narrowband pulses and the symmetrical radiation pattern. By dividing up a meanderlike coil into single elements and a time-delayed firing of the elements, whereby the time delay is given by the distance of the elements and the phase velocity of the wave propagating along the surface, the ultrasonic pulse radiated in one preferred direction becomes broadband by constructive interference. The signals radiated in the opposite direction do no more interfere. Its amplitude is smaller than that of the other direction, so that the transducer becomes uni-directional. This technique can be applied for the excitation of all dispersionless waves (bulk waves and guided waves)

Crosstalk analysis of a broadband data communications system

Science.gov (United States)

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.

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)

Broadband and High power Reactive Jamming Resilient Wireless Communication

Science.gov (United States)

2017-10-21

Broadband and High -power Reactive Jamming Resilient Wireless Communication The views, opinions and/or findings contained in this report are those of... available in extremely hostile environments, where FHSS and DSSS are completely defeated by a broadband and high -power reactive jammer. b. Wireless...SECURITY CLASSIFICATION OF: 1. REPORT DATE (DD-MM-YYYY) 4. TITLE AND SUBTITLE 13. SUPPLEMENTARY NOTES 12. DISTRIBUTION AVAILIBILITY STATEMENT 6. AUTHORS

Robot Towed Shortwave Infrared Camera for Specific Surface Area Retrieval of Surface Snow

Science.gov (United States)

Elliott, J.; Lines, A.; Ray, L.; Albert, M. R.

2017-12-01

Optical grain size and specific surface area are key parameters for measuring the atmospheric interactions of snow, as well as tracking metamorphosis and allowing for the ground truthing of remote sensing data. We describe a device using a shortwave infrared camera with changeable optical bandpass filters (centered at 1300 nm and 1550 nm) that can be used to quickly measure the average SSA over an area of 0.25 m^2. The device and method are compared with calculations made from measurements taken with a field spectral radiometer. The instrument is designed to be towed by a small autonomous ground vehicle, and therefore rides above the snow surface on ultra high molecular weight polyethylene (UHMW) skis.

Frequency Doubling Broadband Light in Multiple Crystals

International Nuclear Information System (INIS)

Alford, William J.; Smith, Arlee V.

2000-01-01

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

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.

Wireless Broadband Access and Accounting Schemes

Institute of Scientific and Technical Information of China (English)

无

2003-01-01

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

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.

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...

An improved phase-locked loop method for automatic resonance frequency tracing based on static capacitance broadband compensation for a high-power ultrasonic transducer.

Science.gov (United States)

Dong, Hui-juan; Wu, Jian; Zhang, Guang-yu; Wu, Han-fu

2012-02-01

The phase-locked loop (PLL) method is widely used for automatic resonance frequency tracing (ARFT) of high-power ultrasonic transducers, which are usually vibrating systems with high mechanical quality factor (Qm). However, a heavily-loaded transducer usually has a low Qm because the load has a large mechanical loss. In this paper, a series of theoretical analyses is carried out to detail why the traditional PLL method could cause serious frequency tracing problems, including loss of lock, antiresonance frequency tracing, and large tracing errors. The authors propose an improved ARFT method based on static capacitance broadband compensation (SCBC), which is able to address these problems. Experiments using a generator based on the novel method were carried out using crude oil as the transducer load. The results obtained have demonstrated the effectiveness of the novel method, compared with the conventional PLL method, in terms of improved tracing accuracy (±9 Hz) and immunity to antiresonance frequency tracing and loss of lock.

Forests, nitrogen and albedo, a very interesting trio indeed

Directory of Open Access Journals (Sweden)

Borghetti M

2009-01-01

Full Text Available A short comment is made on a recent paper (Ollinger et al. 2008 which shows that forest ecosystem carbon uptake in temperate and boreal forests is directly related to canopy nitrogen concentration and that both carbon uptake capacity and canopy nitrogen concentration are positively correlated with shortwave surface albedo measured with broad-band satellite sensors.

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

A non-invasive, quantitative study of broadband spectral responses in human visual cortex.

Directory of Open Access Journals (Sweden)

Eline R Kupers

Full Text Available Currently, non-invasive methods for studying the human brain do not routinely and reliably measure spike-rate-dependent signals, independent of responses such as hemodynamic coupling (fMRI and subthreshold neuronal synchrony (oscillations and event-related potentials. In contrast, invasive methods-microelectrode recordings and electrocorticography (ECoG-have recently measured broadband power elevation in field potentials (~50-200 Hz as a proxy for locally averaged spike rates. Here, we sought to detect and quantify stimulus-related broadband responses using magnetoencephalography (MEG. Extracranial measurements like MEG and EEG have multiple global noise sources and relatively low signal-to-noise ratios; moreover high frequency artifacts from eye movements can be confounded with stimulus design and mistaken for signals originating from brain activity. For these reasons, we developed an automated denoising technique that helps reveal the broadband signal of interest. Subjects viewed 12-Hz contrast-reversing patterns in the left, right, or bilateral visual field. Sensor time series were separated into evoked (12-Hz amplitude and broadband components (60-150 Hz. In all subjects, denoised broadband responses were reliably measured in sensors over occipital cortex, even in trials without microsaccades. The broadband pattern was stimulus-dependent, with greater power contralateral to the stimulus. Because we obtain reliable broadband estimates with short experiments (~20 minutes, and with sufficient signal-to-noise to distinguish responses to different stimuli, we conclude that MEG broadband signals, denoised with our method, offer a practical, non-invasive means for characterizing spike-rate-dependent neural activity for addressing scientific questions about human brain function.

Exceptionally omnidirectional broadband light harvesting scheme for multi-junction concentrator solar cells achieved via ZnO nanoneedles

KAUST Repository

Yeh, Li-Ko; Tian, Wei-Cheng; Lai, Kun-Yu; He, Jr-Hau

2016-01-01

GaInP/GaAs/Ge triple-junction concentrator solar cells with significant efficiency enhancement were demonstrated with antireflective ZnO nanoneedles. The novel nanostructure was attained with a Zn(NO3)2-based solution containing vitamin C. Under one sun AM 1.5G solar spectrum, conversion efficiency of the triple-junction device was improved by 23.7% via broadband improvement in short-circuit currents of 3 sub-cells after the coverage by the nanoneedles with a graded refractive index profile. The efficiency enhancement further went up to 45.8% at 100 suns. The performance boost through the nanoneedles also became increasingly pronounced in the conditions of high incident angles and the cloudy weather, e.g. 220.0% of efficiency enhancement was observed at the incident angle of 60°. These results were attributed to the exceptional broadband omnidirectionality of the antireflective nanoneedles.

Exceptionally omnidirectional broadband light harvesting scheme for multi-junction concentrator solar cells achieved via ZnO nanoneedles

KAUST Repository

Yeh, Li-Ko

2016-12-14

GaInP/GaAs/Ge triple-junction concentrator solar cells with significant efficiency enhancement were demonstrated with antireflective ZnO nanoneedles. The novel nanostructure was attained with a Zn(NO3)2-based solution containing vitamin C. Under one sun AM 1.5G solar spectrum, conversion efficiency of the triple-junction device was improved by 23.7% via broadband improvement in short-circuit currents of 3 sub-cells after the coverage by the nanoneedles with a graded refractive index profile. The efficiency enhancement further went up to 45.8% at 100 suns. The performance boost through the nanoneedles also became increasingly pronounced in the conditions of high incident angles and the cloudy weather, e.g. 220.0% of efficiency enhancement was observed at the incident angle of 60°. These results were attributed to the exceptional broadband omnidirectionality of the antireflective nanoneedles.

Broadband electromagnetic analysis of compacted kaolin

International Nuclear Information System (INIS)

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

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. (paper)

Optimizing the updated Goddard shortwave radiation Weather Research and Forecasting (WRF) scheme for Intel Many Integrated Core (MIC) architecture

Science.gov (United States)

Mielikainen, Jarno; Huang, Bormin; Huang, Allen H.-L.

2015-05-01

Intel Many Integrated Core (MIC) ushers in a new era of supercomputing speed, performance, and compatibility. It allows the developers to run code at trillions of calculations per second using the familiar programming model. In this paper, we present our results of optimizing the updated Goddard shortwave radiation Weather Research and Forecasting (WRF) scheme on Intel Many Integrated Core Architecture (MIC) hardware. The Intel Xeon Phi coprocessor is the first product based on Intel MIC architecture, and it consists of up to 61 cores connected by a high performance on-die bidirectional interconnect. The co-processor supports all important Intel development tools. Thus, the development environment is familiar one to a vast number of CPU developers. Although, getting a maximum performance out of Xeon Phi will require using some novel optimization techniques. Those optimization techniques are discusses in this paper. The results show that the optimizations improved performance of the original code on Xeon Phi 7120P by a factor of 1.3x.

Measurement uncertainty in broadband radiofrequency radiation level measurements

Directory of Open Access Journals (Sweden)

Vulević Branislav D.

2014-01-01

Full Text Available For the evaluation of measurement uncertainty in the measurement of broadband radio frequency radiation, in this paper we propose a new approach based on the experience of the authors of the paper with measurements of radiofrequency electric field levels conducted in residential areas of Belgrade and over 35 municipalities in Serbia. The main objective of the paper is to present practical solutions in the evaluation of broadband measurement uncertainty for the in-situ RF radiation levels. [Projekat Ministarstva nauke Republike Srbije, br. III43009

77 FR 14340 - Proposed Information Collection; Comment Request; Broadband Technology Opportunities Program...

Science.gov (United States)

2012-03-09

..., broadband service by public safety agencies; and (5) To stimulate the demand for broadband, economic growth, and job creation. OMB also requires agencies administering grant programs to [[Page 14341

Broadband enhancement of photoluminance from colloidal metal halide perovskite nanocrystals on plasmonic nanostructured surfaces.

Science.gov (United States)

Zhang, Si; Liang, Yuzhang; Jing, Qiang; Lu, Zhenda; Lu, Yanqing; Xu, Ting

2017-11-07

Metal halide perovskite nanocrystals (NCs) as a new kind of promising optoelectronic material have attracted wide attention due to their high photoluminescence (PL) quantum yield, narrow emission linewidth and wideband color tunability. Since the PL intensity always has a direct influence on the performance of optoelectronic devices, it is of vital importance to improve the perovskite NCs' fluorescence emission efficiency. Here, we synthesize three inorganic perovskite NCs and experimentally demonstrate a broadband fluorescence enhancement of perovskite NCs by exploiting plasmonic nanostructured surface consisting of nanogrooves array. The strong near-field optical localization associated with surface plasmon polariton-coupled emission effect generated by the nanogrooves array can significantly boost the absorption of perovskite NCs and tailor the fluorescence emissions. As a result, the PL intensities of perovskite NCs are broadband enhanced with a maximum factor higher than 8-fold achieved in experimental demonstration. Moreover, the high efficiency PL of perovskite NCs embedded in the polymer matrix layer on the top of plasmonic nanostructured surface can be maintained for more than three weeks. These results imply that plasmonic nanostructured surface is a good candidate to stably broadband enhance the PL intensity of perovskite NCs and further promote their potentials in the application of visible-light-emitting devices.

The influence of scrotonin on survival of Candida guillermondii, irradiated by short-wave ultraviolet

International Nuclear Information System (INIS)

Strakhovskaya, M.G.; Frajkin, G.Ya.; Goncharenko, E.N.

1982-01-01

A study was made on the influence of serotonin on survival of Candida quilliermondu yeast irradiated by 254 nm short-wave ultraviolet. It was established that incubation with serotonin, leading to its penetration inside cells causes two opposite effects - protection from ultraviolet inactivation in preliminary incubation and intensification of cells death in postradiation incubation. Serotonin action is similar to the effects induced in C. guillermondii yeast by 334 nm long-wave ultraviolet light, that is serotonin possesses photomimetic effect. The data obtained are considered as conformaition of participation of serotonin photoinduced synthesis in manifestation of effects of long-wave ultraviolet light action on yeast

An ultra-broadband multilayered graphene absorber

KAUST Repository

Amin, Muhammad; Farhat, Mohamed; Bagci, Hakan

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

Impact of cyclostationarity on fan broadband noise prediction

Science.gov (United States)

Wohlbrandt, A.; Kissner, C.; Guérin, S.

2018-04-01

One of the dominant noise sources of modern Ultra High Bypass Ratio (UHBR) engines is the interaction of the rotor wakes with the leading edges of the stator vanes in the fan stage. While the tonal components of this noise generation mechanism are fairly well understood by now, the broadband components are not. This calls to further the understanding of the broadband noise generation in the fan stage. This article introduces a new extension to the Random Particle Mesh (RPM) method, which accommodates in-depth studies of the impact of cyclostationary wake characteristics on the broadband noise in the fan stage. The RPM method is used to synthesize a turbulence field in the stator domain using a URANS simulation characterized by time-periodic turbulence and mean flow. The rotor-stator interaction noise is predicted by a two-dimensional CAA computation of the stator cascade. The impact of cyclostationarity is decomposed into various effects, which are separately investigated. This leads to the finding that the periodic turbulent kinetic energy (TKE) and periodic flow have only a negligible effect on the radiated sound power. The impact of the periodic integral length scale (TLS) is, however, substantial. The limits of a stationary representation of the TLS are demonstrated making this new extension to the RPM method indispensable when background and wake TKE are of comparable level. Good agreement of the predictions with measurements obtained from the 2015 AIAA Fan Broadband Noise Prediction Workshop are also shown.

Broad-band hard X-ray reflectors

DEFF Research Database (Denmark)

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

1997-01-01

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

Broadband unidirectional cloaks based on flat metasurface focusing lenses

International Nuclear Information System (INIS)

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

2015-01-01

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

Broadband unidirectional cloaks based on flat metasurface focusing lenses

Science.gov (United States)

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

2015-08-01

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

Analysis of United States' Broadband Policy

National Research Council Canada - National Science Library

Uzarski, Joel S

2007-01-01

.... With every month that passes, the United States fails to close the gap in the digital divide both inside its borders as well as among the other countries that lead the world in broadband penetration...

Broadband sub-THz spectroscopy modules integrated in 65-nm CMOS technology

NARCIS (Netherlands)

Matters-Kammerer, M.K.; van Goor, D.; Tripodi, L.

2017-01-01

The design and characterization of a broadband 20-480 GHz continuously tuneable on-chip spectrometer based on non-linear transmission lines in 65-nm CMOS technology is presented. The design procedure of the sampler that detects the ultra-broadband signal from the transmitter in time and frequency

Self-assembled nanotextures impart broadband transparency to glass windows and solar cell encapsulants

Science.gov (United States)

Liapis, Andreas C.; Rahman, Atikur; Black, Charles T.

2017-10-01

Most optoelectronic components and consumer display devices require glass or plastic covers for protection against the environment. Optical reflections from these encapsulation layers can degrade the device performance or lessen the user experience. Here, we use a highly scalable self-assembly based approach to texture glass surfaces at the nanoscale, reducing reflections by such an extent so as to make the glass essentially invisible. Our nanotextures provide broadband antireflection spanning visible and infrared wavelengths (450-2500 nm) that is effective even at large angles of incidence. This technology can be used to improve the performance of photovoltaic devices by eliminating reflection losses, which can be as much as 8% for glass encapsulated cells. In contrast, solar cells encapsulated with nanotextured glass generate the same photocurrent as when operated without a cover. Ultra-transparent windows having surface nanotextures on both sides can withstand three times more optical fluence than commercial broadband antireflection coatings, making them useful for pulsed laser applications.

Design of a temperature control system using incremental PID algorithm for a special homemade shortwave infrared spatial remote sensor based on FPGA

Science.gov (United States)

Xu, Zhipeng; Wei, Jun; Li, Jianwei; Zhou, Qianting

2010-11-01

An image spectrometer of a spatial remote sensing satellite requires shortwave band range from 2.1μm to 3μm which is one of the most important bands in remote sensing. We designed an infrared sub-system of the image spectrometer using a homemade 640x1 InGaAs shortwave infrared sensor working on FPA system which requires high uniformity and low level of dark current. The working temperature should be -15+/-0.2 Degree Celsius. This paper studies the model of noise for focal plane array (FPA) system, investigated the relationship with temperature and dark current noise, and adopts Incremental PID algorithm to generate PWM wave in order to control the temperature of the sensor. There are four modules compose of the FPGA module design. All of the modules are coded by VHDL and implemented in FPGA device APA300. Experiment shows the intelligent temperature control system succeeds in controlling the temperature of the sensor.

Phosphorene/ZnO Nano-Heterojunctions for Broadband Photonic Nonvolatile Memory Applications.

Science.gov (United States)

Hu, Liang; Yuan, Jun; Ren, Yi; Wang, Yan; Yang, Jia-Qin; Zhou, Ye; Zeng, Yu-Jia; Han, Su-Ting; Ruan, Shuangchen

2018-06-10

High-performance photonic nonvolatile memory combining photosensing and data storage with low power consumption ensures the energy efficiency of computer systems. This study first reports in situ derived phosphorene/ZnO hybrid heterojunction nanoparticles and their application in broadband-response photonic nonvolatile memory. The photonic nonvolatile memory consistently exhibits broadband response from ultraviolet (380 nm) to near infrared (785 nm), with controllable shifts of the SET voltage. The broadband resistive switching is attributed to the enhanced photon harvesting, a fast exciton separation, as well as the formation of an oxygen vacancy filament in the nano-heterojunction. In addition, the device exhibits an excellent stability under air exposure compared with reported pristine phosphorene-based nonvolatile memory. The superior antioxidation capacity is believed to originate from the fast transfer of lone-pair electrons of phosphorene. The unique assembly of phosphorene/ZnO nano-heterojunctions paves the way toward multifunctional broadband-response data-storage techniques. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

WIRELESS FIDELITY (Wi-Fi) BROADBAND NETWORK ...

African Journals Online (AJOL)

ES Obe

broadband speed and coverage, while Wi-Fi can be integrated with WiMAX networks to provide Internet ... Microwave Access (WiMAX), IEEE 802.11 standards. 1.0 INTRODUCTION .... These 2G systems provided circuit- switched data ...

Spectral composition of shortwave radiation reflected and deep penetrating into snow near the Barentsburg settlement (Svalbard

Directory of Open Access Journals (Sweden)

P. N. Svyashchennikov

2015-01-01

Full Text Available Data on spectral composition of shortwave radiation that is reflected from snow and penetrates deep into the snow cover obtained near the Barentsburg settlement (Svalbard are discussed in the paper. Measurements were made by the use of the spectral radiometer TriOS Ramses within the wavelength range of 280–950 nm. The results will allow more proper taking account of the anthropogenic pollution effects on the radiative properties of snow cover under conditions of industrial activity related to the coal extraction and burning in Barentsburg.

Broadband over powerline : advances and applications

Energy Technology Data Exchange (ETDEWEB)

Gunther, E.W. [EnerNex Corp., Knoxville, TN (United States)

2006-07-01

An overview of the broadband over powerline (BPL) industry was presented with reference to the history of the technology; current trials and deployments; applications; and, technologies currently in service. The presentation offers background information and a history of BPL, an early adopters test lab, BPL deployment map and access BPL stats. A comparison of wireless, hybrid and fiber optic communication technologies was presented along with access BPL systems and a review of how BPL can enhance utility operations. Diagnostic monitoring, operations improvement, system protection, load and DG management, distribution automation, and customer interface were included in an eye chart for operations enhancement. Suggestions on how BPL can reduce distribution line radio interference were presented along with examples of how BPL EMI analysis can find faulty electrical equipment. BPL customer services include Internet access, consumer portal, voice over Internet protocol, video surveillance, video conferencing, and building automation and energy management. BPL technical issues include installation, operation and electromagnetic compatibility. BPL regulations and standard efforts were described. It was concluded that BPL has a variety of applications in the utility sector including power quality, reliability monitoring and improvement. 1 tab., 7 figs.

High efficiency and broadband acoustic diodes

Science.gov (United States)

Fu, Congyi; Wang, Bohan; Zhao, Tianfei; Chen, C. Q.

2018-01-01

Energy transmission efficiency and working bandwidth are the two major factors limiting the application of current acoustic diodes (ADs). This letter presents a design of high efficiency and broadband acoustic diodes composed of a nonlinear frequency converter and a linear wave filter. The converter consists of two masses connected by a bilinear spring with asymmetric tension and compression stiffness. The wave filter is a linear mass-spring lattice (sonic crystal). Both numerical simulation and experiment show that the energy transmission efficiency of the acoustic diode can be improved by as much as two orders of magnitude, reaching about 61%. Moreover, the primary working band width of the AD is about two times of the cut-off frequency of the sonic crystal filter. The cut-off frequency dependent working band of the AD implies that the developed AD can be scaled up or down from macro-scale to micro- and nano-scale.

Sensitivity improvement for correlations involving arginine side-chain Nε/Hε resonances in multi-dimensional NMR experiments using broadband 15N 180o pulses

International Nuclear Information System (INIS)

Iwahara, Junji; Clore, G. Marius

2006-01-01

Due to practical limitations in available 15 N rf field strength, imperfections in 15 N 180 o pulses arising from off-resonance effects can result in significant sensitivity loss, even if the chemical shift offset is relatively small. Indeed, in multi-dimensional NMR experiments optimized for protein backbone amide groups, cross-peaks arising from the Arg guanidino 15 Nε (∼85 ppm) are highly attenuated by the presence of multiple INEPT transfer steps. To improve the sensitivity for correlations involving Arg Nε-Hε groups, we have incorporated 15 N broadband 180 deg. pulses into 3D 15 N-separated NOE-HSQC and HNCACB experiments. Two 15 N-WURST pulses incorporated at the INEPT transfer steps of the 3D 15 N-separated NOE-HSQC pulse sequence resulted in a ∼1.5-fold increase in sensitivity for the Arg Nε-Hε signals at 800 MHz. For the 3D HNCACB experiment, five 15 N Abramovich-Vega pulses were incorporated for broadband inversion and refocusing, and the sensitivity of Arg 1 Hε- 15 Nε- 13 Cγ/ 13 Cδ correlation peaks was enhanced by a factor of ∼1.7 at 500 MHz. These experiments eliminate the necessity for additional experiments to assign Arg 1 Hε and 15 Nε resonances. In addition, the increased sensitivity afforded for the detection of NOE cross-peaks involving correlations with the 15 Nε/ 1 Hε of Arg in 3D 15 N-separated NOE experiments should prove to be very useful for structural analysis of interactions involving Arg side-chains

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....

Reduction of broadband noise in vehicles by means of active feedforward control

OpenAIRE

Misol, Malte; Haase, Thomas; Monner, Hans Peter

2015-01-01

Broadband noise in a vehicle’s interior is an important issue because of its negative impact on the passengersʼ comfort and wellbeing. The perception of this broadband noise can increase due to the use of new, less noisy drive concepts and the accompanying loss of masking noise compo-nents. This contribution focuses on the reduction of the transmission of external broadband distur-bances through lightweight panel structures (e.g. a car’s roof liner or an aircraft sidewall panel) by means of a...

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.

Numerical simulation of ultrasound-thermotherapy combining nonlinear wave propagation with broadband soft-tissue absorption.

Science.gov (United States)

Ginter, S

2000-07-01

Ultrasound (US) thermotherapy is used to treat tumours, located deep in human tissue, by heat. It features by the application of high intensity focused ultrasound (HIFU), high local temperatures of about 90 degrees C and short treating time of a few seconds. Dosage of the therapy remains a problem. To get it under control, one has to know the heat source, i.e. the amount of absorbed US power, which shows nonlinear influences. Therefore, accurate simulations are essential. In this paper, an improved simulation model is introduced which enables accurate investigations of US thermotherapy. It combines nonlinear US propagation effects, which lead to generation of higher harmonics, with a broadband frequency-power law absorption typical for soft tissue. Only the combination of both provides a reliable calculation of the generated heat. Simulations show the influence of nonlinearities and broadband damping for different source signals on the absorbed US power density distribution.

Sub-50-nm self-assembled nanotextures for enhanced broadband antireflection in silicon solar cells.

Science.gov (United States)

Rahman, Atikur; Ashraf, Ahsan; Xin, Huolin; Tong, Xiao; Sutter, Peter; Eisaman, Matthew D; Black, Charles T

2015-01-21

Materials providing broadband light antireflection have applications as highly transparent window coatings, military camouflage, and coatings for efficiently coupling light into solar cells and out of light-emitting diodes. In this work, densely packed silicon nanotextures with feature sizes smaller than 50 nm enhance the broadband antireflection compared with that predicted by their geometry alone. A significant fraction of the nanotexture volume comprises a surface layer whose optical properties differ substantially from those of the bulk, providing the key to improved performance. The nanotexture reflectivity is quantitatively well-modelled after accounting for both its profile and changes in refractive index at the surface. We employ block copolymer self-assembly for precise and tunable nanotexture design in the range of ~10-70 nm across macroscopic solar cell areas. Implementing this efficient antireflection approach in crystalline silicon solar cells significantly betters the performance gain compared with an optimized, planar antireflection coating.

Energy and carbon balances in cheatgrass, an essay in autecology. [Shortwave radiation, radiowave radiation

Energy Technology Data Exchange (ETDEWEB)

Hinds, W.T.

1975-01-01

An experiment to determine the fates of energy and carbon in cheatgrass (Bromus tectorum L.) was carried out on steep (40/sup 0/) north- and south-facing slopes on a small earth mound, using many small lysimeters to emulate swards of cheatgrass. Meteorological conditions and energy fluxes that were measured included air and soil temperatures, relative humidity, wind speed, incoming shortwave radiation, net all-wave radiation, heat flux to the soil, and evaporation and transpiration separately. The fate of photosynthetically fixed carbon during spring growth was determined by analysis of the plant tissues into mineral nutrients, crude protein, crude fat, crude fiber, and nitrogen-free extract (NFE) for roots, shoots, and seeds separately. (auth)

Developments of sausages in a z-pinch with short-wave perturbation of a boundary

International Nuclear Information System (INIS)

Vikhrev, V.V.; Ivanov, V.V.; Rozanova, G.A.

1989-01-01

A numeric simulation of sausage evolution in z-pinch during short-wave excitation of the boundary of plasma column pinch is carried out. The simulation has shown that due to nonlinear development of sausages in a pinch plasma colomn the cavities filled with a magnetic field in a rarefied pinch plasma are formed. Simultaneously compact column of tense plasma whose temperature is much higher than the average temperature of pinch plasma column are formed on the pinch axis. In the region of inlet in the cavity plasma is radially directed due to ponderomotoric force 1/2 x jB up to velocities greatly increasing the thermal velocity of ions in a plasma column

Broadband luminescent materials in waveguide geometry

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

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.

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...

Advanced broadband baffle materials

International Nuclear Information System (INIS)

Seals, R.D.

1991-01-01

In this paper broadband performance characteristics of robust, light-weight, diffuse-absorptive baffle surfaces fabricated from sputter-deposited beryllium on cross-rolled Be ingot sheet material and on Be foam, plasma sprayed beryllium, plasma sprayed boron-on-beryllium, and chemical vapor deposited boron carbide on graphite are described and compared to Martin Black. An overview of the Optics Manufacturing Operations Development and Integration Laboratory (MODIL) Advanced Optical Baffle Program will be discussed

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...

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

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.

Why Broadband Internet Should Not Be the Priority for Developing Countries

Science.gov (United States)

Noam, Eli

With broadband Internet connectivity progressing, the focus of attention has shifted to those left behind. The shorthand word for this concern is the classic “digital divide.” Underlying virtually every discussion about a gap in broadband penetrations is the implicit assumption that overcoming such a divide is a priority (Meschi et al., 2004; Crandall et al., 2007). But maybe we first should pause for a moment and understand the implications of ending this divide. If we do that, we might end up changing our perspective on Internet policy in an important way: away from a focus on broadband Internet connectivity, and towards universal connectivity and the creation of E-transactions, E-commerce, and E-content.

Nonlinear effects in the propagation of shortwave transverse sound in pure superconductors

International Nuclear Information System (INIS)

Gal'perin, Y.

1982-01-01

Various mechanisms are analyzed which lead to nonlinear phenomena (e.g., the dependence of the absorption coefficient and of the velocity of sound on its intensity) in the propagation of transverse shortwave sound in pure superconductors (the wavelength of the sound being much less than the mean free path of the quasiparticles). It is shown that the basic mechanism, over a wide range of superconductor parameters and of the sound intensity, is the so-called momentum nonlinearity. The latter is due to the distortion (induced by the sound wave) of the quasimomentum distribution of resonant electrons interacting with the wave. The dependences of the absorption coefficient and of the sound velocity on its intensity and on the temperature are analyzed in the vicinity of the superconducting transition point. The feasibility of an experimental study of nonlinear acoustic phenomena in the case of transverse sound is considered

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

Science.gov (United States)

Yang, Yuanqing; Li, Qiang; Qiu, Min

2016-01-19

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

Establishing BRDF calibration capabilities through shortwave infrared

Science.gov (United States)

Georgiev, Georgi T.; Butler, James J.; Thome, Kurt; Cooksey, Catherine; Ding, Leibo

2017-09-01

Satellite instruments operating in the reflective solar wavelength region require accurate and precise determination of the Bidirectional Reflectance Distribution Functions (BRDFs) of the laboratory and flight diffusers used in their pre-flight and on-orbit calibrations. This paper advances that initial work and presents a comparison of spectral Bidirectional Reflectance Distribution Function (BRDF) and Directional Hemispherical Reflectance (DHR) of Spectralon*, a common material for laboratory and onorbit flight diffusers. A new measurement setup for BRDF measurements from 900 nm to 2500 nm located at NASA Goddard Space Flight Center (GSFC) is described. The GSFC setup employs an extended indium gallium arsenide detector, bandpass filters, and a supercontinuum light source. Comparisons of the GSFC BRDF measurements in the shortwave infrared (SWIR) with those made by the National Institute of Standards and Technology (NIST) Spectral Tri-function Automated Reference Reflectometer (STARR) are presented. The Spectralon sample used in this study was 2 inch diameter, 99% white pressed and sintered Polytetrafluoroethylene (PTFE) target. The NASA/NIST BRDF comparison measurements were made at an incident angle of 0° and viewing angle of 45° . Additional BRDF data not compared to NIST were measured at additional incident and viewing angle geometries and are not presented here. The total combined uncertainty for the measurement of BRDF in the SWIR range made by the GSFC scatterometer is less than 1% (k = 1). This study is in support of the calibration of the Radiation Budget Instrument (RBI) and Visible Infrared Imaging Radiometer Suit (VIIRS) instruments of the Joint Polar Satellite System (JPSS) and other current and future NASA remote sensing missions operating across the reflected solar wavelength region.

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.

Adding seismic broadband analysis to characterize Andean backarc seismicity in Argentina

Science.gov (United States)

Alvarado, P.; Giuliano, A.; Beck, S.; Zandt, G.

2007-05-01

Characterization of the highly seismically active Andean backarc is crucial for assessment of earthquake hazards in western Argentina. Moderate-to-large crustal earthquakes have caused several deaths, damage and drastic economic consequences in Argentinean history. We have studied the Andean backarc crust between 30°S and 36°S using seismic broadband data available from a previous ("the CHARGE") IRIS-PASSCAL experiment. We collected more than 12 terabytes of continuous seismic data from 22 broadband instruments deployed across Chile and Argentina during 1.5 years. Using free software we modeled full regional broadband waveforms and obtained seismic moment tensor inversions of crustal earthquakes testing for the best focal depth for each event. We also mapped differences in the Andean backarc crustal structure and found a clear correlation with different types of crustal seismicity (i.e. focal depths, focal mechanisms, magnitudes and frequencies of occurrence) and previously mapped terrane boundaries. We now plan to use the same methodology to study other regions in Argentina using near-real time broadband data available from the national seismic (INPRES) network and global seismic networks operating in the region. We will re-design the national seismic network to optimize short-period and broadband seismic station coverage for different network purposes. This work is an international effort that involves researchers and students from universities and national government agencies with the goal of providing more information about earthquake hazards in western Argentina.

Broadband silicon polarization beam splitter with a high extinction ratio using a triple-bent-waveguide directional coupler.

Science.gov (United States)

Ong, Jun Rong; Ang, Thomas Y L; Sahin, Ezgi; Pawlina, Bryan; Chen, G F R; Tan, D T H; Lim, Soon Thor; Png, Ching Eng

2017-11-01

We report on the design and experimental demonstration of a broadband silicon polarization beam splitter (PBS) with a high extinction ratio (ER)≥30  dB. This was achieved using triple-bent-waveguide directional coupling in a single PBS, and cascaded PBS topology. For the single PBS, the bandwidths for an ER≥30  dB are 20 nm for the quasi-TE mode, and 70 nm for the quasi-TM mode when a broadband light source (1520-1610 nm) was employed. The insertion loss (IL) varies from 0.2 to 1 dB for the quasi-TE mode and 0.2-2 dB for the quasi-TM mode. The cascaded PBS improved the bandwidth of the quasi-TE mode for an ER≥30  dB to 90 nm, with a low IL of 0.2-2 dB. To the best of our knowledge, our PBS system is one of the best broadband PBSs with an ER as high as ∼42  dB and a low IL below 1 dB around the central wavelength, and experimentally demonstrated using edge-coupling.

Broadband Direct UVA irradiance measurement for clear skies evaluated using a smartphone

International Nuclear Information System (INIS)

Igoe, D.; Parisi, A.V.

2015-01-01

UVA wavelengths (320-400 nm) have been implicated in recent studies to contribute to melanoma induction and skin photo-aging in humans and damage to plants. The use of smartphones in UVA observations is a way to supplement measurements made by traditional radiometric and spectro-radiometric technology. Although the smartphone image sensor is not capable of determining broadband UVA irradiances, these can be reconstructed from narrowband irradiances, which the smartphone, with narrowband and neutral density filters, can quantify with discrepancies not exceeding 5 %. Three models that reconstruct direct broadband clear sky UVA were developed from narrowband irradiances derived from smartphone image sensor pixel data with coefficients of determination of between 0.97 and 0.99. Reasonable accuracy and precision in determining the direct broadband UVA was maintained for observations made with solar zenith angles as high as 70 deg. . The developed method has the potential to increase the uptake of the measurement of broadband UVA irradiances. (authors)

Compact, low-loss and broadband photonic crystal circulator based on a star-type ferrite rod

Directory of Open Access Journals (Sweden)

Xiang Xi

Full Text Available We propose and investigate a compact, low-loss and broadband circulator based on a star-type ferrite rod in two-dimensional square-lattice photonic crystals. Only one ferrite rod is required to be inserted in our structure. Firstly, the performances of circulator based on the star-type, circle, and square ferrite rod are compared, showing that the circulator with the star-type ferrite rod performs better than the other two ones. And then, based on the star-type ferrite rod circulator, four cases of improvement, in which the background rods around the center ferrite rod are replaced respectively by the backward-triangle, forward-triangle, backward-semicircle, and forward-semicircle rods, are investigated to modulate the coupling between the center magneto-optical micro-cavity and the corresponding waveguides. The results show that, with proper parameters, all the four cases can greatly improve the output properties of the circulator, and different cases have its own advantages. The mechanism behind these improvements is also discussed. Finite-element method is used to calculate the characteristics of the circulator and Nelder-Mead optimization method is employed to obtain the optimized parameters. The ideas presented here are useful for designing broadband, low insertion loss, and high-isolation circulators which have potential application in integrated photonic crystal devices. Keywords: Photonic crystals, Circulator, Magneto-optical material, Photonic crystal waveguides

A variable-tune spatial heterodyne spectrometer for broadband spectral line studies in the visible and near-UV

Science.gov (United States)

Dawson, Olivia R.; Harris, Walter M.

2017-11-01

Reflective Spatial Heterodyne Spectroscopy (SHS) is an interferometric technique that combines high resolving power and a large input acceptance angle in a format that is compact enough for use at small telescope focal planes and in spacecraft observations of targets in the visible to far ultra-violet (FUV) spectral range. SHS instruments are well suited to the study of faint, extended emission line sources, particularly in the UV where stellar background continuum becomes weak. Their primary limitation comes from the limited spatial sampling of the output interference pattern generated by the incoming spectral source, which limits their use to narrow bandpass near the central tuning wavelength. We describe a the first light results from a broadband SHS that can be used to scan the tuning wavelength across a bandpass extending from 300 to 700 nm. The limitations on the bandpass are arbitrary and can easily be extended into the UV or near infrared. We discuss the results of these validation program and the potential improvements that could be used to expand and/or improve the broadband spectral response of the instrument.

Broadband and tunable optical parametric generator for remote detection of gas molecules in the short and mid-infrared.

Science.gov (United States)

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

2015-04-01

The development of a novel broadband and tunable optical parametric generator (OPG) is presented. The OPG properties are studied numerically and experimentally in order to optimize the generator's use in a broadband spectroscopic LIDAR operating in the short and mid-infrared. This paper discusses trade-offs to be made on the properties of the pump, crystal, and seeding signal in order to optimize the pulse spectral density and divergence while enabling energy scaling. A seed with a large spectral bandwidth is shown to enhance the pulse-to-pulse stability and optimize the pulse spectral density. A numerical model shows excellent agreement with output power measurements; the model predicts that a pump having a large number of longitudinal modes improves conversion efficiency and pulse stability.

Broadband wavelength conversion in hydrogenated amorphous silicon waveguide with silicon nitride layer

Science.gov (United States)

Wang, Jiang; Li, Yongfang; Wang, Zhaolu; Han, Jing; Huang, Nan; Liu, Hongjun

2018-01-01

Broadband wavelength conversion based on degenerate four-wave mixing is theoretically investigated in a hydrogenated amorphous silicon (a-Si:H) waveguide with silicon nitride inter-cladding layer (a-Si:HN). We have found that enhancement of the non-linear effect of a-Si:H waveguide nitride intermediate layer facilitates broadband wavelength conversion. Conversion bandwidth of 490 nm and conversion efficiency of 11.4 dB were achieved in a numerical simulation of a 4 mm-long a-Si:HN waveguide under 1.55 μm continuous wave pumping. This broadband continuous-wave wavelength converter has potential applications in photonic networks, a type of readily manufactured low-cost highly integrated optical circuits.

Polarization-independent broadband meta-holograms via polarization-dependent nanoholes.

Science.gov (United States)

Zhang, Xiaohu; Li, Xiong; Jin, Jinjin; Pu, Mingbo; Ma, Xiaoliang; Luo, Jun; Guo, Yinghui; Wang, Changtao; Luo, Xiangang

2018-05-17

Composed of ultrathin metal or dielectric nanostructures, metasurfaces can manipulate the phase, amplitude and polarization of electromagnetic waves at a subwavelength scale, which is promising for flat optical devices. In general, metasurfaces composed of space-variant anisotropic units are sensitive to the incident polarization due to the inherent polarization dependent geometric phase. Here, we implement polarization-independent broadband metasurface holograms constructed by polarization-dependent anisotropic elliptical nanoholes by elaborate design of complex amplitude holograms. The fabricated meta-hologram exhibits a polarization insensitive feature with an acceptable image quality. We verify the feasibility of the design algorithm for three-dimensional (3D) meta-holograms with simulation and the feasibility for two-dimensional (2D) meta-holograms is experimentally demonstrated at a broadband wavelength range from 405 nm to 632.8 nm. The effective polarization-independent broadband complex wavefront control with anisotropic elliptical nanoholes proposed in this paper greatly promotes the practical applications of the metasurface in technologies associated with wavefront manipulation, such as flat lens, colorful holographic displays and optical storage.

Energy efficiency in future wireless broadband networks

CSIR Research Space (South Africa)

Masonta, MT

2012-10-01

Full Text Available greener economy and environment. In this research, we investigate the concept of green radio communications in wireless networks and discuss approaches for energy efficient solutions in wireless broadband network deployments. These solutions include...

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

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

... generates a 1.4% increase in gross domestic product (GDP) in low-income countries. ... Africa offers a good example of the potential benefits and challenges of ... the policy challenges related to providing affordable broadband services; ...

Broadband Photometric Reverberation Mapping Analysis on SDSS-RM and Stripe 82 Quasars

Science.gov (United States)

Zhang, Haowen; Yang, Qian; Wu, Xue-Bing

2018-02-01

We modified the broadband photometric reverberation mapping (PRM) code, JAVELIN, and tested the availability to get broad-line region time delays that are consistent with the spectroscopic reverberation mapping (SRM) project SDSS-RM. The broadband light curves of SDSS-RM quasars produced by convolution with the system transmission curves were used in the test. We found that under similar sampling conditions (evenly and frequently sampled), the key factor determining whether the broadband PRM code can yield lags consistent with the SRM project is the flux ratio of the broad emission line to the reference continuum, which is in line with the previous findings. We further found a critical line-to-continuum flux ratio, about 6%, above which the mean of the ratios between the lags from PRM and SRM becomes closer to unity, and the scatter is pronouncedly reduced. We also tested our code on a subset of SDSS Stripe 82 quasars, and found that our program tends to give biased lag estimations due to the observation gaps when the R-L relation prior in Markov Chain Monte Carlo is discarded. The performance of the damped random walk (DRW) model and the power-law (PL) structure function model on broadband PRM were compared. We found that given both SDSS-RM-like or Stripe 82-like light curves, the DRW model performs better in carrying out broadband PRM than the PL model.

Characteristics of hybrid broadcast broadband television (HbbTV

Directory of Open Access Journals (Sweden)

Jakšić Branimir

2017-01-01

Full Text Available This paper describes the working principle of hybrid broadcast-broadband TV (Hybrid Broadcast Broadband TV - HbbTV. The architecture of HbbTV system is given, the principle of its operation, as well as an overview of HbbTV specification standards that are in use, with their basic characteristics. Here are described the services provided by Hybrid TV. It is also provided an overview of the distribution of HbbTV services in Europe in terms of the number of TV channels that HbbTV services offer, the number of active hybrid TV devices, HbbTV standards which are in use and models of broadcast networks used to distribute HbbTV service.

Efficient composite broadband polarization retarders and polarization filters

Science.gov (United States)

Dimova, E.; Ivanov, S. S.; Popkirov, G.; Vitanov, N. V.

2014-12-01

A new type of broadband polarization half-wave retarder and narrowband polarization filters are described and experimentally tested. Both, the retarders and the filters are designed as composite stacks of standard optical half-wave plates, each of them twisted at specific angles. The theoretical background of the proposed optical devices was obtained by analogy with the method of composite pulses, known from the nuclear and quantum physics. We show that combining two composite filters built from different numbers and types of waveplates, the transmission spectrum is reduced from about 700 nm to about 10 nm width.We experimentally demonstrate that this method can be applied to different types of waveplates (broadband, zero-order, multiple order, etc.).

Broadband 0.25-um Gallium Nitride (GaN) Power Amplifier Designs

Science.gov (United States)

2017-08-14

networking, and sensor systems of interest to Department of Defense applications, particularly for next-generation radar systems. Broadband, efficient, high...simulations of MMIC (3–6 GHz, 28 V/180 mA) 1.75-mm HEMT power amplifier ............................................... 13 Fig. 20 Simple schematic...design simple , a single 1.75-mm high-electron-mobility transistor (HEMT) was used for a preliminary ideal design of the broadband power amplifier

Broadband terahertz generation using the semiconductor-metal transition in VO2

Directory of Open Access Journals (Sweden)

Nicholas A. Charipar

2016-01-01

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

77 FR 62461 - Implementing Public Safety Broadband Provisions of the Middle Class Tax Relief and Job Creation...

Science.gov (United States)

2012-10-15

... Wireless Broadband Network,'' ``Special Purpose Bankruptcy Remote Entity,'' ``Upper 700 MHz D Block license... definitions ``700 MHz Public/Private Partnership,'' ``Network Assets Holder,'' ``Network Sharing Agreement...,'' ``Public safety broadband network operator,'' ``Shared Wireless Broadband Network, '' ``Special Purpose...

EM Simulation Accuracy Enhancement for Broadband Modeling of On-Wafer Passive Components

DEFF Research Database (Denmark)

Johansen, Tom Keinicke; Jiang, Chenhui; Hadziabdic, Dzenan

2007-01-01

This paper describes methods for accuracy enhancement in broadband modeling of on-wafer passive components using electromagnetic (EM) simulation. It is shown that standard excitation schemes for integrated component simulation leads to poor correlation with on-wafer measurements beyond the lower...... GHz frequency range. We show that this is due to parasitic effects and higher-order modes caused by the excitation schemes. We propose a simple equivalent circuit for the parasitic effects in the well-known ground ring excitation scheme. An extended L-2L calibration method is shown to improve...

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...

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.

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...

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...

Spectrally shaped broadband study of up-conversion in Y2O3:Er3+

International Nuclear Information System (INIS)

Lytle, A.L.; Gagnon, E.; Tulchinsky, L.; Krebs, J.K.

2014-01-01

We present a novel scheme for studying up-conversion through excited state absorption (ESA) by using a broadband excitation source with spectral shaping capabilities. Up-conversion processes have typically been investigated using a single, narrowband excitation source, when the two steps of the process are coincident in frequency, which is often made possible by broadening mechanisms of the intermediate excited state manifolds. Thus, narrowband sources are limited in the systems they can excite and what material information they can provide. With broadband light, we are able to drive up-conversion with non-coincident frequencies as well. Finally, by windowing the spectrum, we determine the optimal excitation bandwidth for low-concentration (1%) Y 2 O 3 :Er 3+ nanocrystals. - Highlights: • Broadband excitation light is used to drive up-conversion in Y 2 O 3 :Er 3+ . • Broadband light excites all available transitions in the two-photon process. • A spectral shaping technique is used to alter the excitation frequencies present. • The optimal excitation bandwidth is measured by windowing the spectrum. • Broadband excitation reveals information inaccessible by narrowband sources

Experimental broadband absorption enhancement in silicon nanohole structures with optimized complex unit cells.

Science.gov (United States)

Lin, Chenxi; Martínez, Luis Javier; Povinelli, Michelle L

2013-09-09

We design silicon membranes with nanohole structures with optimized complex unit cells that maximize broadband absorption. We fabricate the optimized design and measure the optical absorption. We demonstrate an experimental broadband absorption about 3.5 times higher than an equally-thick thin film.

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.

Pyrolysis of Helical Coordination Polymers for Metal-Sulfide-Based Helices with Broadband Chiroptical Activity.

Science.gov (United States)

Hirai, Kenji; Yeom, Bongjun; Sada, Kazuki

2017-06-27

Fabrication of chiroptical materials with broadband response in the visible light region is vital to fully realize their potential applications. One way to achieve broadband chiroptical activity is to fabricate chiral nanostructures from materials that exhibit broadband absorption in the visible light region. However, the compounds used for chiroptical materials have predominantly been limited to materials with narrowband spectral response. Here, we synthesize Ag 2 S-based nanohelices derived from helical coordination polymers. The right- and left-handed coordination helices used as precursors are prepared from l- and d-glutathione with Ag + and a small amount of Cu 2+ . The pyrolysis of the coordination helices yields right- and left-handed helices of Cu 0.12 Ag 1.94 S/C, which exhibit chiroptical activity spanning the entire visible light region. Finite element method simulations substantiate that the broadband chiroptical activity is attributed to synergistic broadband light absorption and light scattering. Furthermore, another series of Cu 0.10 Ag 1.90 S/C nanohelices are synthesized by choosing the l- or d-Glu-Cys as starting materials. The pitch length of nanohelicies is controlled by changing the peptides, which alters their chiroptical properties. The pyrolysis of coordination helices enables one to fabricate helical Ag 2 S-based materials that enable broadband chiroptical activity but have not been explored owing to the lack of synthetic routes.

Magnetization pinning in conducting films demonstrated using broadband ferromagnetic resonance

Science.gov (United States)

Kostylev, M.; Stashkevich, A. A.; Adeyeye, A. O.; Shakespeare, C.; Kostylev, N.; Ross, N.; Kennewell, K.; Magaraggia, R.; Roussigné, Y.; Stamps, R. L.

2010-11-01

The broadband microstrip ferromagnetic resonance (FMR), cavity FMR, and Brillouin light scattering spectroscopy techniques have been applied for detection and characterization of a magnetic inhomogeneity in a film sample. In the case of a 100 nm thick permalloy film, an additional magnetically depleted top sublayer has been detected due to pinning effect it produces on the magnetization in the bulk of the film. The pinning results in appearance of an exchange standing spin wave mode in the broadband FMR absorption spectrum, whose amplitudes are different depending on whether the film or the film substrate faces the microstrip transducer. Comparison of the experimental amplitudes for this mode with results of our theory for both film placements revealed that the depleted layer is located at the film surface facing away from the film substrate. Subsequent broadband FMR characterization of a large number of other presumably single-layer films with thicknesses in the range 30-100 nm showed the same result.

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.

Volterra series based predistortion for broadband RF power amplifiers with memory effects

Institute of Scientific and Technical Information of China (English)

Jin Zhe; Song Zhihuan; He Jiaming

2008-01-01

RF power amplifiers(PAs)are usually considered as memoryless devices in most existing predistortion techniques.However,in broadband communication systems,such as WCDMA,the PA memory effects are significant,and memoryless predistortion cannot linearize the PAs effectively.After analyzing the PA memory effects,a novel predistortion method based on the simplified Volterra series is proposed to linearize broadband RF PAs with memory effects.The indirect learning architecture is adopted to design the predistortion scheme and the recursive least squares algorithm with forgetting factor is applied to identify the parameters of the predistorter.Simulation results show that the proposed predistortion method can compensate the nonlinear distortion and memory effects of broadband RF PAs effectively.

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....

A photo-excited broadband to dual-band tunable terahertz prefect metamaterial polarization converter

Science.gov (United States)

Zhu, Jianfeng; Yang, Yang; Li, Shufang

2018-04-01

A new and simple design of photo-excited broadband to dual-band tunable terahertz (THz) metamaterial cross polarization converter is proposed in this paper. The tunable converter is a sandwich structure with the center-cut cross-shaped metallic patterned structure as a resonator, the middle dielectric layer as a spacer and the bottom metallic film as the ground. The conductivity of the photoconductive semiconductor (Silicon) filled in the gap of the cross-shaped metallic resonator can be tuned by the incident pump power, leading to an easy modulation of the electromagnetic response of the proposed converter. The results show that the proposed cross-polarization converter can be tuned from a broadband with polarization conversion ratio (PCR) beyond 95% (1.86-2.94 THz) to dual frequency bands (fl = 1 . 46 THz &fh = 2 . 9 THz). The conversion peaks can reach 99.9% for the broadband and, 99.5% (fl) and 99.7% (fh) for the dual-band, respectively. Most importantly, numerical simulations demonstrate that the broadband/dual-band polarization conversion mechanism of the converter originates from the localized surface plasmon modes, which make the design simple and different from previous designs. With these good features, the proposed broadband to dual-band tunable polarization converter is expected to be used in widespread applications.

Progress on Broadband Access to the Internet and Use of Mobile Devices in the United States.

Science.gov (United States)

Serrano, Katrina J; Thai, Chan L; Greenberg, Alexandra J; Blake, Kelly D; Moser, Richard P; Hesse, Bradford W

Healthy People 2020 (HP2020) aims to improve population health outcomes through several objectives, including health communication and health information technology. We used 7 administrations of the Health Information National Trends Survey to examine HP2020 goals toward access to the Internet through broadband and mobile devices (N = 34 080). We conducted descriptive analyses and obtained predicted marginals, also known as model-adjusted risks, to estimate the association between demographic characteristics and use of mobile devices. The HP2020 target (7.7% of the US population) for accessing the Internet through a cellular network was surpassed in 2014 (59.7%), but the HP2020 target (83.2%) for broadband access fell short (63.8%). Sex and age were associated with accessing the Internet through a cellular network throughout the years (Wald F test, P Internet through mobile devices presents an opportunity for technology-based health interventions that should be explored.

Integrated Broadband Quantum Cascade Laser

Science.gov (United States)

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

2016-01-01

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

Mastering the broadband challenge: next-generation SONET in a packet world

Science.gov (United States)

Farhi, Eyal

2001-10-01

The continuing liberalization of the world's telecommunications markets and the progressive convergence of voice, data, video and Internet communication are prompting telecommunication service providers to both expand and enhance their service capabilities. As bandwidth-hungry applications proliferate, and the demand for data and data services grows, the requirement for broadband communications appears to be insatiable. To provide the expected level of service in this environment of rapidly increasing demand, telcos and service providers must invest in an expanded network. However, to remain competitive and profitable, they must also continue to leverage their existing infrastructure investment. This paper will examine the current challenges network operators are facing today with the deployment of broadband technologies as they strive to maintain existing infrastructure investments while providing new services to their customers and developing added value network operations. This paper will explore various broadband technologies (optical/wireless) that operate on the primary SDH/SONET standards, their topologies and inherent benefits, which provide operators with solutions to the broadband challenge. New customer demands, such as high-speed Data transmissions (increased Internet use), coupled with operators' continuous need for network optimization, have thrown a wrench into daily operations. Therefore, the need to modernize existing networks has become paramount.

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.

Tapered fluorotellurite microstructured fibers for broadband supercontinuum generation.

Science.gov (United States)

Wang, Fang; Wang, Kangkang; Yao, Chuanfei; Jia, Zhixu; Wang, Shunbin; Wu, Changfeng; Qin, Guanshi; Ohishi, Yasutake; Qin, Weiping

2016-02-01

Fluorotellurite microstructured fibers (MFs) based on TeO2-BaF2-Y2O3 glasses are fabricated by using a rod-in-tube method. Tapered fluorotellurite MFs with varied transition region lengths are prepared by employing an elongation machine. By using a tapered fluorotellurite MF with a transition region length of ∼3.3  cm as the nonlinear medium and a 1560 nm femtosecond fiber laser as the pump source, broadband supercontinuum generation covering from 470 to 2770 nm is obtained. The effects of the transition region length of the tapered fluorotellurite MF on supercontinuum generation are also investigated. Our results show that tapered fluorotellurite MFs are promising nonlinear media for generating broadband supercontinuum light expanding from visible to mid-infrared spectral region.

Fourier transform holography with extended references using a coherent ultra-broadband light source.

Science.gov (United States)

Tenner, Vasco T; Eikema, Kjeld S E; Witte, Stefan

2014-10-20

We demonstrate a technique that enables lensless holographic imaging with extended reference structures, using ultra-broadband radiation sources for illumination. We show that this 'two-pulse imaging' approach works with one- and two-dimensional HERALDO reference structures, and demonstrate that the obtained spectrally resolved data can be used to improve the signal-to-noise ratio in the final image. Intensity stitching of multiple exposures is applied to increase the detected dynamic range, leading to an improved image reconstruction. Furthermore, we show that a combination of holography and iterative phase retrieval can be used to obtain high-quality images quickly and reliably, by using the HERALDO reconstruction as the initial support constraint in the iterative phase retrieval algorithm. A signal-to-noise improvement of two orders of magnitude is achieved compared to the basic HERALDO result.

75 FR 29516 - Broadband Researchers' Data Workshop

Science.gov (United States)

2010-05-26

... foundation for long-term economic stability and prosperity.\\1\\ The increased availability and use of... telecommunications policies pertaining to the Nation's economic and technological advancement. In order to achieve... stakeholders to develop and implement economic and regulatory policies that foster broadband deployment and...

75 FR 27984 - Broadband Technology Opportunities Program

Science.gov (United States)

2010-05-19

... applications, including: streaming video (surveillance, remote monitoring); digital imaging; automatic vehicle location; computer-aided dispatching; electronic mail; mapping and GPS; remote database access; report... entities to deploy public safety broadband systems using the 700 MHz spectrum licensed to the PSST.\\13\\ The...

Broadband Shock Noise in Internally-Mixed Dual-Stream Jets

Science.gov (United States)

Bridges, James E.

2009-01-01

Broadband shock noise (BBSN) has been studied in some detail in single-flow jets and recently in dual-stream jets with separate flow exhaust systems. Shock noise is of great concern in these latter cases because of the noise created for the aircraft cabin by the underexpanded nozzle flow at cruise. Another case where shock noise is of concern is in the case of future supersonic aircraft that are expected to have bypass ratios small enough to justify internally mixed exhaust systems, and whose mission will push cycles to the point of imperfectly expanded flows. Dual-stream jets with internally mixed plume have some simplifying aspects relative to the separate flow jets, having a single shock structure given by the common nozzle pressure. This is used to separate the contribution of the turbulent shear layer to the broadband shock noise. Shock structure is held constant while the geometry and strength of the inner and merged shear layers are varying by changing splitter area ratio and core stream temperature. Flow and noise measurements are presented which document the efforts at separating the contribution of the inner shear layer to the broadband shock noise.

Advances in the density profile evaluation from broadband reflectometry on ASDEX upgrade

International Nuclear Information System (INIS)

Varela, P.; Manso, M.; Conway, G.

2001-01-01

The high temporal and spatial resolutions provided by broadband microwave reflectometry make it an attractive diagnostic technique to measure the density profile in fusion plasmas. However, great problems have been encountered due to the plasma turbulence that difficult, and sometimes prevent, the routine evaluation of density profiles. Advanced broadband systems employ ultra-fast sweeping in an attempt to perform the profile measurement in a time window smaller than the temporal scale of the main plasma fluctuations but this is not sufficient. Indeed, abrupt plasma movements and/or spatial turbulence always affect the reflectometry signals, as shown by numerical studies (with both one- and two-dimensional codes), for the case of ultra-fast sweeping and pulse radar systems. For this reason not only the system performance is important but the software tools also play a crucial role for reflectometry to become a standard density profile diagnostic. Here we present the recent advances towards automatic evaluation of density profiles from broadband reflectometry on ASDEX Upgrade. For regimes with moderate levels of plasma turbulence, density profiles are obtained from single reflectometry samples (temporal resolution of 20 μs), and for higher turbulence levels average profiles are obtained from bursts of ultra-fast (20 μs), closely spaced (10 μs) sweeps. This method improved the accuracy and reliability of density profiles, which can now be obtained automatically from the edge to the bulk plasma - using reflectometry alone - in most plasma regimes of ASDEX Upgrade. New data processing capability has been implemented that allows the profiles to be available to the end-users 10-12 minutes after each discharge. These developments were possible due to the flexibility and high performance of the control and data acquisition systems and to the large number of measurements that can be performed with the diagnostic during each discharge (720 profiles both on the low- and

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, 

Comparison of VP broadband tiltmeter and VS vertical pendulum tiltmeter

Directory of Open Access Journals (Sweden)

Wugang Ma

2015-05-01

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

Broadband S-band class E HPA

NARCIS (Netherlands)

Wanum, M.; van Dijk, R.; de Hek, A.P.; van Vliet, Frank Edward

2009-01-01

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

Broadband seismic : case study modeling and data processing

Science.gov (United States)

Cahyaningtyas, M. B.; Bahar, A.

2018-03-01

Seismic data with wide range of frequency is needed due to its close relation to resolution and the depth of the target. Low frequency provides deeper penetration for the imaging of deep target. In addition, the wider the frequency bandwidth, the sharper the wavelet. Sharp wavelet is responsible for high-resolution imaging and is very helpful to resolve thin bed. As a result, the demand for broadband seismic data is rising and it spurs the technology development of broadband seismic in oil and gas industry. An obstacle that is frequently found on marine seismic data is the existence of ghost that affects the frequency bandwidth contained on the seismic data. Ghost alters bandwidth to bandlimited. To reduce ghost effect and to acquire broadband seismic data, lots of attempts are used, both on the acquisition and on the processing of seismic data. One of the acquisition technique applied is the multi-level streamer, where some streamers are towed on some levels of depth. Multi-level streamer will yield data with varied ghost notch shown on frequency domain. If the ghost notches are not overlapping, the summation of multi-level streamer data will reduce the ghost effect. The result of the multi-level streamer data processing shows that reduction of ghost notch on frequency domain indeed takes place.

Broadband Acoustic Transmission Enhancement through a Structured Stiff Plate with Locally Resonant Elements

International Nuclear Information System (INIS)

Li Yong; Liang Bin; Zou Xin-Ye; Cheng Jian-Chun

2012-01-01

Broadband acoustic transmission enhancement (ATE) is realized for a periodically structured stiff plate without any opening that is conventionally thought to be only capable of supporting narrowband ATE, by introducing locally resonant (LR) elements. This exotic phenomenon is interpreted by analyzing the vibration pattern of the structure-induced LR modes, and is well modeled by a simple 'spring-mass' system which reveals the contribution of the LR effect to the important broadband performance. Our findings should help to better understand the physical mechanism of ATE and may have potential impact on ultrasonic applications such as broadband acoustic filters or compact acoustic devices in subwavelength scale

77 FR 36903 - Accelerating Broadband Infrastructure Deployment

Science.gov (United States)

2012-06-20

... the Nation's global competitiveness in the 21st century, driving job creation, promoting innovation, and expanding markets for American businesses. Broadband access also affords public safety agencies... infrastructure has been deployed in a vast majority of communities across the country, today too many areas still...

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

Science.gov (United States)

2013-09-03

... goal of increased broadband deployment and use in the United States. The BroadbandMatch Web site began... proposed collection of information is necessary for the proper performance of the functions of the agency... the quality, utility, and clarity of the information to be collected; and (d) ways to minimize the...

Broadband seismic deployments in East Antarctica: IPY contribution to monitoring the Earth’s interiors

Directory of Open Access Journals (Sweden)

Masaki Kanao

2014-06-01

Full Text Available “Deployment of broadband seismic stations on the Antarctica continent” is an ambitious project to improve the spatial resolution of seismic data across the Antarctic Plate and surrounding regions. Several international collaborative programs for the purpose of geomonitoring were conducted in Antarctica during the International Polar Year (IPY 2007-2008. The Antarctica’s GAmburtsev Province (AGAP; IPY #147, the GAmburtsev Mountain SEISmic experiment (GAMSEIS, a part of AGAP, and the Polar Earth Observing Network (POLENET; IPY #185 were major contributions in establishing a geophysical network in Antarctica. The AGAP/GAMSEIS project was an internationally coordinated deployment of more than 30 broadband seismographs over the crest of the Gambursev Mountains (Dome-A, Dome-C and Dome-F area. The investigations provide detailed information on crustal thickness and mantle structure; provide key constraints on the origin of the Gamburtsev Mountains; and more broadly on the structure and evolution of the East Antarctic craton and subglacial environment. From GAMSEIS and POLENET data obtained, local and regional seismic signals associated with ice movements, oceanic loading, and local meteorological variations were recorded together with a significant number of teleseismic events. In this chapter, in addition to the Earth’s interiors, we will demonstrate some of the remarkable seismic signals detected during IPY that illustrate the capabilities of broadband seismometers to study the sub-glacial environment, particularly at the margins of Antarctica. Additionally, the AGAP and POLENET stations have an important role in the Federation of Digital Seismographic Network (FDSN in southern high latitude.

Broadband phase-preserved optical elevator

OpenAIRE

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

2011-01-01

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

The development and characterization of advanced broadband mirror coatings for the far-UV

Science.gov (United States)

Egan, Arika; Fleming, Brian T.; Wiley, James; Quijada, Manuel; Del Hoyo, Javier; Hennessy, John; Hicks, Brian; France, Kevin; Kruczek, Nicholas; Erickson, Nicholas

2017-08-01

We present a progress report on the development of new broadband mirror coatings that demonstrate > 80% reflectivities from 1020-5000Å. Four different coating recipes are presented as candidates for future far-ultraviolet (FUV) sensitive broadband observatories. Three samples were first coated with aluminum (Al) and lithium fluoride (LiF) at the NASA Goddard Space Flight Center (GSFC) using a new high-temperature physical vapor deposition (PVD) process. Two of these samples then had an ultrathin (10-20 Å) protective coat of either magnesium fluoride (MgF2) or aluminum fluoride (AlF3) applied using atomic later deposition (ALD) at the NASA Jet Propulsion Laboratory (JPL). A fourth sample was coated with Al and a similar high temperature PVD coating of AlF3. Polarized reflectivities into the FUV for each sample were obtained through collaboration with the Synchrotron Ultraviolet Radiation Facility at the National Institute of Standards and Technology. We present a procedure for using these reflectivities as a baseline for calculating the optical constants of each coating recipe. Given these results, we describe plans for improving our measurement methodology and techniques to develop and characterize these coating recipes for future FUV missions.

The Importance of Broadband for Socio-Economic Development: A Perspective from Rural Australia

Directory of Open Access Journals (Sweden)

Julie Freeman

2016-10-01

Full Text Available Advanced connectivity offers rural communities prospects for socio-economic development. Despite Australia’s national broadband infrastructure plans, inferior availability and quality of rural Internet connections remain persistent issues. This article examines the impact of limited connectivity on rural socio-economic opportunities, drawing from the views of twelve citizens from the Boorowa local government area in New South Wales. The available fixed wireless and satellite connections in Boorowa are slow and unreliable, and remote regions in the municipality are still without any Internet access. Participants identified four key areas in their everyday lives that are impacted by insufficient connectivity: business development, education, emergency communication, and health. Rural citizens often already face challenges in these areas, and infrastructure advancements in urban spaces can exacerbate rural-urban disparities. Participants’ comments demonstrated apprehension that failure to improve connectivity would result in adverse long-term consequences for the municipality. This article suggests that current broadband policy frameworks require strategic adaptations to account for the socio-economic and geographic contexts of rural communities. In order to narrow Australia’s rural-urban digital divide, infrastructure developments should be prioritised in the most underserved regions.

Evaluation of Shortwave Infrared Atmospheric Correction for Ocean Color Remote Sensing of Chesapeake Bay

Science.gov (United States)

Werdell, P. Jeremy; Franz, Bryan A.; Bailey, Sean W.

2010-01-01

The NASA Moderate Resolution Imaging Spectroradiometer onboard the Aqua platform (MODIS-Aqua) provides a viable data stream for operational water quality monitoring of Chesapeake Bay. Marine geophysical products from MODIS-Aqua depend on the efficacy of the atmospheric correction process, which can be problematic in coastal environments. The operational atmospheric correction algorithm for MODIS-Aqua requires an assumption of negligible near-infrared water-leaving radiance, nL(sub w)(NIR). This assumption progressively degrades with increasing turbidity and, as such, methods exist to account for non-negligible nL(sub w)(NIR) within the atmospheric correction process or to use alternate radiometric bands where the assumption is satisfied, such as those positioned within shortwave infrared (SWIR) region of the spectrum. We evaluated a decade-long time-series of nL(sub w)(lambda) from MODIS-Aqua in Chesapeake Bay derived using NIR and SWIR bands for atmospheric correction. Low signal-to-noise ratios (SNR) for the SWIR bands of MODIS-Aqua added noise errors to the derived radiances, which produced broad, flat frequency distributions of nL(sub w)(lambda) relative to those produced using the NIR bands. The SWIR approach produced an increased number of negative nL(sub w)(lambda) and decreased sample size relative to the NIR approach. Revised vicarious calibration and regional tuning of the scheme to switch between the NIR and SWIR approaches may improve retrievals in Chesapeake Bay, however, poor SNR values for the MODIS-Aqua SWIR bands remain the primary deficiency of the SWIR-based atmospheric correction approach.

Broadband nanophotonic waveguides and resonators based on epitaxial GaN thin films

Energy Technology Data Exchange (ETDEWEB)

Bruch, Alexander W.; Xiong, Chi; Leung, Benjamin; Poot, Menno; Han, Jung; Tang, Hong X., E-mail: hong.tang@yale.edu [Department of Electrical Engineering, Yale University, New Haven, Connecticut 06511 (United States)

2015-10-05

We demonstrate broadband, low loss optical waveguiding in single crystalline GaN grown epitaxially on c-plane sapphire wafers through a buffered metal-organic chemical vapor phase deposition process. High Q optical microring resonators are realized in near infrared, infrared, and near visible regimes with intrinsic quality factors exceeding 50 000 at all the wavelengths we studied. TEM analysis of etched waveguide reveals growth and etch-induced defects. Reduction of these defects through improved material and device processing could lead to even lower optical losses and enable a wideband photonic platform based on GaN-on-sapphire material system.

Not all carp are created equal: Impacts of broadband sound on common carp swimming behavior

Science.gov (United States)

Murchy, Kelsie; Vetter, Brooke J.; Brey, Marybeth; Amberg, Jon J.; Gaikowski, Mark; Mensinger, Allen F.

2016-01-01

Bighead carp (Hypophthalmichthys nobilis), silver carp (H. molitrix) (hereafter: bigheaded carps), and common carp (Cyprinus carpio) are invasive fish causing negative impacts throughout their North American range. To control their movements, non-physical barriers are being developed. Broadband sound (0.06 to 10 kHz) has shown potential as an acoustic deterrent for bigheaded carps, but the response of common carp to broadband sound has not been evaluated. Since common carp are ostariophysians, possessing Weberian ossicles similar to bigheaded carps, it is possible that sound can be used as an acoustical deterrent for all three species. Behavioral responses to a broadband sound were evaluated for common carp in an outdoor concrete pond. Common carp responded a median of 3.0 (1st Q: 1.0, 3rd Q: 6.0) consecutive times to the broadband sound which was lower than silver carp and bighead carp to the same stimulus. The current study shows that common carp demonstrate an inconsistent negative phonotaxis response to a broadband sound, and seem to habituate to the sound quickly.

Estimation of radiative forcing and chore length of shallow convective clouds (SCC) based on broadband pyranometer measurement network

Science.gov (United States)

Shi, H.

2017-12-01

We presented a method to identify and calculate cloud radiative forcing (CRF) and horizontal chore length (L) of shallow convective clouds (SCC) using a network of 9 broadband pyranometers. The analyzing data was collected from the SCC campaign during two years summers (2015 2016) at Baiqi site over Inner Mongolia grassland. The network of pyranometers was operated across a spatial domain covering 42.16-42.30° N and 114.83-114.98° E. The SCC detection method was verified by observer reports and cameras, which showed that the detection method and human observations were in agreement about 75 %. The differences between the SCC detection method and human observations can be responsible for following factors: 1) small or dissipating clouds can be neglected for the value of 1 min of temporal resolution of pyranometer; 2) human observation recorded weather conditions four times every day; 3) SCC was indistinguishable from coexistence of SCC and Cirrus (Ci); 4) the SCC detection method is weighted toward clouds crossing the sun's path, while the human observer can view clouds over the entire sky. The deviation of L can be attributed to two factors: 1) the accuracy of wind speed at height of SCC and the ratio of horizontal and vertical length play a key role in determine values of L; 2) the effect of variance of solar zenith angle can be negligible. The downwelling shortwave CRF of SCC was -134.1 Wm-2. The average value of L of SCC was 1129 m. Besides, the distribution of normalized cloud chore length agreed well with power-law fit.

Examining Factors Influencing the Behavioral Intention to Adopt Broadband in Malaysia

Science.gov (United States)

Dwivedi, Yogesh K.; Selamat, Mohamad H.; Wahab, Muhammad S. Abd; Samsudin, Mohd A. Mat; Lal, Banita

The aim of this study was to examine the factors affecting the adoption of broadband Internet in a developing country context by focusing upon Malaysia. The data relating to these factors was collected using a survey approach. The findings of this paper suggest that perceived usefulness, perceived ease of use, and social influence are significant factors for explaining the behavioral intention to adopt broadband Internet by Malaysian accountants. The paper proceeds to outline the research limitations, theoretical contributions, and implications for practice.

Multiyear Statistics of 2-D Shortwave Radiative Effects at Three ARM Sites

Science.gov (United States)

Varnai, Tamas

2010-01-01

This study examines the importance of horizontal photon transport effects, which are not considered in the 1-D calculations of solar radiative heating used by most atmospheric dynamical models. In particular, the paper analyzes the difference between 2-D and 1-D radiative calculations for 2-D vertical cross-sections of clouds that were observed at three sites over 2- to 3-year periods. The results show that 2-D effects increase multiyear 24-hour average total solar absorption by about 4.1 W/sq m, 1.2 W/sq m, and 0.3 W/sq m at a tropical, mid-latitude, and arctic site, respectively. However, 2-D effects are often much larger than these average values, especially for high sun and for convective clouds. The results also reveal a somewhat unexpected behavior, that horizontal photon transport often enhances solar heating even for oblique sun. These findings underscore the need for fast radiation calculation methods that can allow atmospheric dynamical simulations to consider the inherently multidimensional nature of shortwave radiative processes.

Broadband polarization-independent and low-profile optically transparent metamaterial absorber

Science.gov (United States)

Li, Long; Xi, Rui; Liu, Haixia; Lv, Zhiyong

2018-05-01

A transparent metamaterial absorber with simultaneously high optical transparency and broadband microwave absorption is presented in this paper. Consisting of a two-layer soda-lime glass substrate and three-layer patch-shaped indium tin oxide (ITO) films, the proposed absorber has advantages of broadband absorption with an absorptivity higher than 85% in the range from 6.1 to 22.1 GHz, good polarization insensitiveness, a high transparency, a low profile, and wide-incident-angle stability. A prototype of the proposed absorber is fabricated and experimentally measured to demonstrate its excellent performance. The measured results agree well with the theoretical design and numerical simulations.

Broadband sound blocking in phononic crystals with rotationally symmetric inclusions.

Science.gov (United States)

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

2015-09-01

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

Electromagnetically induced transparency with broadband laser pulses

International Nuclear Information System (INIS)

Yavuz, D. D.

2007-01-01

We suggest a scheme to slow and stop broadband laser pulses inside an atomic medium using electromagnetically induced transparency. Extending the suggestion of Harris et al. [Phys. Rev. Lett. 70, 552 (1993)], the key idea is to use matched Fourier components for the probe and coupling laser beams

Water-based metamaterial absorbers for optical transparency and broadband microwave absorption

Science.gov (United States)

Pang, Yongqiang; Shen, Yang; Li, Yongfeng; Wang, Jiafu; Xu, Zhuo; Qu, Shaobo

2018-04-01

Naturally occurring water is a promising candidate for achieving broadband absorption. In this work, by virtue of the optically transparent character of the water, the water-based metamaterial absorbers (MAs) are proposed to achieve the broadband absorption at microwave frequencies and optical transparence simultaneously. For this purpose, the transparent indium tin oxide (ITO) and polymethyl methacrylate (PMMA) are chosen as the constitutive materials. The water is encapsulated between the ITO backed plate and PMMA, serving as the microwave loss as well as optically transparent material. Numerical simulations show that the broadband absorption with the efficiency over 90% in the frequency band of 6.4-30 GHz and highly optical transparency of about 85% in the visible region can be achieved and have been well demonstrated experimentally. Additionally, the proposed water-based MA displays a wide-angle absorption performance for both TE and TM waves and is also robust to the variations of the structure parameters, which is much desired in a practical application.

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.

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

Science.gov (United States)

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

2002-08-01

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

Broadband illumination of superconducting pair breaking photon detectors

International Nuclear Information System (INIS)

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

2016-01-01

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

Asymmetric quantum well broadband thyristor laser

Science.gov (United States)

Liu, Zhen; Wang, Jiaqi; Yu, Hongyan; Zhou, Xuliang; Chen, Weixi; Li, Zhaosong; Wang, Wei; Ding, Ying; Pan, Jiaoqing

2017-11-01

A broadband thyristor laser based on InGaAs/GaAs asymmetric quantum well (AQW) is fabricated by metal organic chemical vapor deposition (MOCVD). The 3-μm-wide Fabry-Perot (FP) ridge-waveguide laser shows an S-shape I-V characteristic and exhibits a flat-topped broadband optical spectrum coverage of ~27 nm (Δ-10 dB) at a center wavelength of ~1090 nm with a total output power of 137 mW under pulsed operation. The AQW structure was carefully designed to establish multiple energy states within, in order to broaden the gain spectrum. An obvious blue shift emission, which is not generally acquired in QW laser diodes, is observed in the broadening process of the optical spectrum as the injection current increases. This blue shift spectrum broadening is considered to result from the prominent band-filling effect enhanced by the multiple energy states of the AQW structure, as well as the optical feedback effect contributed by the thyristor laser structure. Project supported by the National Natural Science Foundation of China (Nos. 61604144, 61504137). Zhen Liu and Jiaqi Wang contributed equally to this work.

Piezo-Phototronic Effect on Selective Electron or Hole Transport through Depletion Region of Vis-NIR Broadband Photodiode.

Science.gov (United States)

Zou, Haiyang; Li, Xiaogan; Peng, Wenbo; Wu, Wenzhuo; Yu, Ruomeng; Wu, Changsheng; Ding, Wenbo; Hu, Fei; Liu, Ruiyuan; Zi, Yunlong; Wang, Zhong Lin

2017-08-01

Silicon underpins nearly all microelectronics today and will continue to do so for some decades to come. However, for silicon photonics, the indirect band gap of silicon and lack of adjustability severely limit its use in applications such as broadband photodiodes. Here, a high-performance p-Si/n-ZnO broadband photodiode working in a wide wavelength range from visible to near-infrared light with high sensitivity, fast response, and good stability is reported. The absorption of near-infrared wavelength light is significantly enhanced due to the nanostructured/textured top surface. The general performance of the broadband photodiodes can be further improved by the piezo-phototronic effect. The enhancement of responsivity can reach a maximum of 78% to 442 nm illumination, the linearity and saturation limit to 1060 nm light are also significantly increased by applying external strains. The photodiode is illuminated with different wavelength lights to selectively choose the photogenerated charge carriers (either electrons or holes) passing through the depletion region, to investigate the piezo-phototronic effect on electron or hole transport separately for the first time. This is essential for studying the basic principles in order to develop a full understanding about piezotronics and it also enables the development of the better performance of optoelectronics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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...

Broadband Wireless Data Acquisition and Control Device, Phase I

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...

Impact of Aerosols on Shortwave and Photosynthetically Active Radiation Balance over Sub-tropical Region in South Asia: Observational and Modeling Approach

Science.gov (United States)

Subba, T.; Pathak, B.

2016-12-01

The North-East Indian Region (NER) (22-30ºN, 89-98ºE) in south Asia sandwiched between two global biodiversity hotspots namely, Himalaya and Indo-Burma, assumes significance owing to its unique topography with mountains in the north, east and south and densely populated Indo Gangetic plains (IGP) towards the west resulting in complex aerosol system. Multi-year (2010-2014) concurrent measurements of aerosol properties and the shortwave radiation budget are examined over four geographically distinct stations of NER operational under Indian Space Research organization's ARFINET (Aerosol Radiative Forcing over India NETwork). An attempt has been made to lessen the ambiguity of forcing estimation by validating the radiative transfer modelled ARF with the CNR4 net radiometer measured values (r2 0.98). The Normalized Difference Vegetation Index and its dependence on the extinction of the photosynthetically active radiation (PAR) due to aerosol are assessed. The spring time enhancement of aerosols in the column has shown significant surface cooling (ARF = -48 ± 5 Wm-2) over the region, while the very high Black Carbon (BC) mass concentrations near the surface (SSA > 0.8) leads to significant atmospheric warming (ARF = +41 ± 7 Wm-2) in the shortwave range. Radiative forcing estimates reveal that the atmospheric forcing by BC could be as high as +30Wm-2 over the western part, which are significantly higher than the eastern part with a consequent heating rate of 1.5 K day-1 revealing an east-west asymmetry over NER. The impact of BC aerosols on the photosynthetic rate varies among different locations ranging from -5±2 Wm-2 to -25±3 Wm-2. Almost 70% of the total atmospheric shortwave radiative absorption is attributed to just 10% contribution of Black Carbon (BC) to total mass concentration and causes a reduction of more than 30% of PAR reaching the surface over Brahmaputra valley due to direct radiative effect. Comparison of previous and the present study shows highest

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.

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

International Nuclear Information System (INIS)

Chen Zhongsheng; Yang Yongmin; Lu Zhimiao; Luo Yanting

2013-01-01

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.

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...

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

The Effect Of Customer Demand And Supplier Performance In Competitive Strategy And Business Performance Case Of Fixed Broadband In Indonesia

Directory of Open Access Journals (Sweden)

Rina D. Pasaribu

2015-08-01

Full Text Available Broadband telecommunication is significantly important to support and improve countrys competitiveness level. However Indonesia performance especially in Fixed Broadband is poor as the penetration rate is very low and far behind from other ASEAN countries. The industry is served by multi operators with one dominant operator. This dominant operator will be studied representing the industry in this study. A qualitative study Pasaribu et al. 2015 related to this paper has found that poor fulfillment of Customer Demand and poor Supplier Performance are two dominant external factors that cause the low performance. A model is proposed to frame the work it consists of four variables Customer Demand Supplier Performance Competitive Strategy and Business Performance. This study aims is use that Pasaribu et al. model directly to business units level to identify and analyze the relationships within the model and significance level of each relationship accordingly. By understanding the priority levels the improvement program could be more effectively planned and implemented. This study is expected to contribute on Fixed Broadband research wich is still very rare especially in Indonesia The research methodology is quantitative methods using survey technique. The respondents are management and customers of the dominant operator business units. Clustering by province regions gave 32 samples from the population of 58 business units. Partial Least Square modelling was used to analise the datas. The main result of this study is that the most significant relationship in the model is Supplier Performance to Competitive Strategy. Furthermore from indicators of Supplier Performance it was found that Quality Relationship has a very high effect among other indicators. By prioritizing these significant constructs it could be expected the related improvement program could be more effective.

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.

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

KAUST Repository

Jiang, Xue; Zhao, Jiajun; Liu, Shi-lei; Liang, Bin; Zou, Xin-ye; Yang, Jing; Qiu, Cheng-Wei; Cheng, Jian-chun

2016-01-01

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.

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?

Wide-angle, polarization-insensitive and broadband absorber based on eight-fold symmetric SRRs metamaterial

Science.gov (United States)

Wu, Dong; Liu, Yumin; Yu, Zhongyuan; Chen, Lei; Ma, Rui; Li, Yutong; Li, Ruifang; Ye, Han

2016-12-01

In this paper, we propose a novel three dimensional metamaterial design with eight-fold rotational symmetry that shows a polarization-insensitive, wide-angle and broadband perfect absorption in the microwave band. By simulation, the polarization-insensitive absorption is over 90% between 26.9 GHz to 32.9 GHz, and the broadband absorption remains a good absorption performance to a wide incident angles for both TE and TM polarizations. The magnetic field distribution are investigated to interpret the physical mechanism of broadband absorption. The broadband absorption is based on overlapping the multiple magnetic resonances at the neighboring frequencies by coupling effects of multiple metallic split-ring resonators (SRRs). Moreover, it is demonstrate that the designed structure can be extended to other frequencies by scale down the size of the unit cell, such as the visible frequencies. The simulated results show that the absorption of the smaller absorber is above 90% in the frequency range from 467 THz to 765 THz(392-642 nm), which include orange to purple light in visible region(400-760nm). The wide-angle and polarization-insensitive stabilities of the smaller absorber is also demonstrated at visible region. The proposed work provides a new design of realization of a polarization-insensitive, wide-angle and broadband absorber ranging different frequency bands, and such a structure has potential application in the fields of solar cell, imaging and detection.

Broadband Spectroscopy of Nanoporous-Gold Promoter

Directory of Open Access Journals (Sweden)

S. K. Nakatani

2014-02-01

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

Diagonalizing sensing matrix of broadband RSE

International Nuclear Information System (INIS)

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

2006-01-01

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

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)

Broadband impedance of the NESTOR storage ring

International Nuclear Information System (INIS)

Androsov, V.P.; Gladkikh, P.I.; Gvozd, A.M.; Karnaukhov, I.M.; Telegin, Yu.N.

2011-01-01

The contributions from lossy and inductive vacuum chamber components to the broadband impedance of the NESTOR storage ring are obtained by using both low-frequency analytical approaches and computer simulations. As was expected considering the small ring circumference (15.44m), the main contributions both to the longitudinal impedance Z || /n and the loss factor k loss come from the RF-cavity. Cavity impedance was also estimated with CST Microwave Studio (CST Studio Suite TM 2006) by simulating coaxial wire method commonly used for impedance measurements. Both estimates agree well. Finally, we performed the simulations of a number of inductive elements with CST Particle Studio 2010 by using wake field solver. We have also evaluated the bunch length in NESTOR taking the conservative estimate of 3 Ohm for the ring broadband impedance and have found that the bunch length s z = 0.5 cm could be obtained in steady state operation mode for the designed bunch current of 10 mA and RF-voltage of 250 kV.

Advanced spectral processing of broadband light using acousto-optic devices with arbitrary transmission functions.

Science.gov (United States)

Molchanov, Vladimir Ya; Yushkov, Konstantin B

2014-06-30

In the paper, we developed a dispersive method for transmission function synthesis of collinear and quasi-collinear acousto-optic tunable filters. General theoretical consideration was performed, and modelling was made for broadband and narrowband signals. Experimental results on spectral shaping of femtosecond laser emission were obtained. Binary spectral encoding of broadband emission was demonstrated.

Active control of time-varying broadband noise and vibrations using a sliding-window Kalman filter

NARCIS (Netherlands)

van Ophem, S.; Berkhoff, Arthur P.; Sas, P.; Moens, D.; Denayer, H.

2014-01-01

Recently, a multiple-input/multiple-output Kalman filter technique was presented to control time-varying broadband noise and vibrations. By describing the feed-forward broadband active noise control problem in terms of a state estimation problem it was possible to achieve a faster rate of

Short-Wave Near-Infrared Spectrometer for Alcohol Determination and Temperature Correction

Directory of Open Access Journals (Sweden)

Qingbo Fu

2012-01-01

Full Text Available A multichannel short-wave near-infrared (SW-NIR spectrometer module based on charge-coupled device (CCD detection was designed. The design relied on a tungsten lamp enhanced by light emitting diodes, a fixed grating monochromator and a linear CCD array. The main advantages were high optical resolution and an optimized signal-to-noise ratio (0.24 nm and 500, resp. in the whole wavelength range of 650 to 1100 nm. An application to alcohol determination using partial least squares calibration and the temperature correction was presented. It was found that the direct transfer method had significant systematic prediction errors due to temperature effect. Generalized least squares weighting (GLSW method was utilized for temperature correction. After recalibration, the RMSEP found for the 25°C model was 0.53% v/v and errors of the same order of magnitude were obtained at other temperatures (15, 35 and 40°C. And an 2 better than 0.99 was achieved for each validation set. The possibility and accuracy of using the miniature SW-NIR spectrometer and GLSW transfer calibration method for alcohol determination at different temperatures were proven. And the analysis procedure was simple and fast, allowing a strict control of alcohol content in the wine industry.

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.

Optimization of the poro-serrated trailing edges for airfoil broadband noise reduction.

Science.gov (United States)

Chong, Tze Pei; Dubois, Elisa

2016-08-01

This paper reports an aeroacoustic investigation of a NACA0012 airfoil with a number of poro-serrated trailing edge devices that contain porous materials of various air flow resistances at the gaps between adjacent members of the serrated-sawtooth trailing edge. The main objective of this work is to determine whether multiple-mechanisms on the broadband noise reduction can co-exist on a poro-serrated trailing edge. When the sawtooth gaps are filled with porous material of low-flow resistivity, the vortex shedding tone at low-frequency could not be completely suppressed at high-velocity, but a reasonably good broadband noise reduction can be achieved at high-frequency. When the sawtooth gaps are filled with porous material of very high-flow resistivity, no vortex shedding tone is present, but the serration effect on the broadband noise reduction becomes less effective. An optimal choice of the flow resistivity for a poro-serrated configuration has been identified, where it can surpass the conventional serrated trailing edge of the same geometry by achieving a further 1.5 dB reduction in the broadband noise while completely suppressing the vortex shedding tone. A weakened turbulent boundary layer noise scattering at the poro-serrated trailing edge is reflected by the lower-turbulence intensity at the near wake centreline across the whole spanwise wavelength of the sawtooth.

Using TV white space spectrum to practise telemedicine: A promising technology to enhance broadband internet connectivity within healthcare facilities in rural regions of developing countries.

Science.gov (United States)

Chavez, Afton; Littman-Quinn, Ryan; Ndlovu, Kagiso; Kovarik, Carrie L

2016-06-01

The following correspondence provides an overview of TV White Space (TVWS) technology, regulations, and potential applications to the health care sector. This report also introduces "Project Kgolagano," a Botswana-based initiative representing the first endeavour to utilize TVWS internet connection for practising telemedicine. TV "white space" refers to the previously unused, wasted spectrum within TV radiofrequency channels that can now be leveraged to obtain broadband internet access. TVWS represents a less costly, faster, and farther-reaching internet connection that is a promising option for connecting the previously unconnected populations of remote and underserved areas. The Botswana-University of Pennsylvania Partnership, Microsoft, Botswana Innovation Hub, Vista Life Sciences, and Global Broadband Solutions have partnered together to bring TVWS wireless broadband access to healthcare facilities in poorly connected regions of Botswana (Lobatse, Francistown, Maun, Gaborone) in order to improve healthcare delivery and facilitate telemedicine in dermatology, cervical cancer screening, and family medicine (HIV/AIDS, TB, general adult and pediatric medicine). © The Author(s) 2015.

Control over multiscale mixing in broadband-forced turbulence

NARCIS (Netherlands)

Kuczaj, Arkadiusz K.; Geurts, Bernardus J.

2008-01-01

The effects of explicit flow modulation on the dispersion of a passive scalar field are studied. Broadband forcing is applied to homogeneous isotropic turbulence to modulate the energy cascading and alter the kinetic energy spectrum. Consequently, a manipulation of turbulent flow can be achieved

Theoretical study of fiber Raman amplifiers by broadband pumps through moment method

International Nuclear Information System (INIS)

Teimorpour, M. H.; Pourmoghadas, A.; Rahimi, L.; Farman, F.; Bahrampour, A.

2007-01-01

The governing equations of Raman optical fiber amplifier with broadband pumps in the steady state are a system of Uncountable Nonlinear Ordinary Differential Equations. In this paper, the Moment Method is used to reduce the uncountable system of Nonlinear Ordinary Differential Equations to a system of finite number of Nonlinear Ordinary Differential Equations. This system of equations is solved numerically. It is shown that the Moment Method is a precise and fast technique for analysis of optical fiber Raman Amplifier with broadband pumps.

Radiative cooling and broadband phenomenon in low-frequency waves

Institute of Scientific and Technical Information of China (English)

无

2000-01-01

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

A broadband Soleil-Babinet compensator for ultrashort light pulses

Science.gov (United States)

Xu, Shixiang; Ma, Yingkun; Cai, Yi; Lu, Xiaowei; Zeng, Xuanke; Chen, Hongyi; Li, Jingzhen

2013-12-01

This letter reports a novel design for a broadband Soleil-Babinet compensator including two pairs of optical wedges plus one plate. According to our birefringent dispersion compensation model, we can eliminate the first-order birefringent phase retardation (BPR) dispersion by using three different birefringent crystals. Our results show a Soleil-Babinet compensator based on a MgF2/ADP/KDP combination can work from 0° to 360° phase compensation with the maximal residual BPR less than 6° within the spectral region from 0.65 to 0.95 μm. The residual BPR of the compensator increases monotonically with the spectral deviation from the designed central wavelength, so our compensator is very suitable to be used for broadband laser pulses with most of their energies around the central wavelengths.

Broad-Band Visually Evoked Potentials: Re(convolution in Brain-Computer Interfacing.

Directory of Open Access Journals (Sweden)

Jordy Thielen

Full Text Available Brain-Computer Interfaces (BCIs allow users to control devices and communicate by using brain activity only. BCIs based on broad-band visual stimulation can outperform BCIs using other stimulation paradigms. Visual stimulation with pseudo-random bit-sequences evokes specific Broad-Band Visually Evoked Potentials (BBVEPs that can be reliably used in BCI for high-speed communication in speller applications. In this study, we report a novel paradigm for a BBVEP-based BCI that utilizes a generative framework to predict responses to broad-band stimulation sequences. In this study we designed a BBVEP-based BCI using modulated Gold codes to mark cells in a visual speller BCI. We defined a linear generative model that decomposes full responses into overlapping single-flash responses. These single-flash responses are used to predict responses to novel stimulation sequences, which in turn serve as templates for classification. The linear generative model explains on average 50% and up to 66% of the variance of responses to both seen and unseen sequences. In an online experiment, 12 participants tested a 6 × 6 matrix speller BCI. On average, an online accuracy of 86% was reached with trial lengths of 3.21 seconds. This corresponds to an Information Transfer Rate of 48 bits per minute (approximately 9 symbols per minute. This study indicates the potential to model and predict responses to broad-band stimulation. These predicted responses are proven to be well-suited as templates for a BBVEP-based BCI, thereby enabling communication and control by brain activity only.

Broadband back grating design for thin film solar cells

KAUST Repository

Janjua, Bilal; Jabbour, Ghassan E.

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.

An improved broadband method to evaluate effective parameters of slab metamaterials in the microwave frequency range

International Nuclear Information System (INIS)

Rybin, O.; Nawaz, T.; Abbasi, T.

2007-01-01

An improved broadband method for determining complex effective refractive index, permittivity and permeability of an arbitrary passive metamaterial in microwave frequency range has been proposed. Evaluation of the effective parameters is realized using the reflection-transmission S-parameters obtained by simulation or experimental measurements and analytically evaluated interface reflection coefficient of the slab. Formulas for evaluation of effective permittivity and permeability which contain the square root of complex functions of S-parameters have been proposed in (1-2). But this method does not propose a way to avoid an ambiguity arising in choosing the square root branch of product of effective permittivity and permeability. Moreover the above calculation procedure requires evaluating the square root branch of function of S-parameters. Proposed way to choose the square root branch gives sometimes mistaken results. Our method is much simple as compared with the above mentioned formulas and it does not require making a choice of square root branch of complex functions of S-parameters in order to evaluate any of the parameters (refractive index, permittivity or permeability). Instead we obtain a formula for complex refractive index which is simple. On the basis of proposed model effective permittivity and permeability for rod meta-materials can be evaluated with enhanced precision and accuracy. Proposed method is easy to be implemented in engineering problems and does not require using complicated mathematical calculations. Comparison of precision of the presented method with the Nicolson-Ross techniques (1-2) has been made using the simulations for different configurations of rod meta-materials. Some discussion concerning the sensitivity of the effective parameters of meta-materials for the accuracy of the frequency dependent S -parameters is also presented in this paper. (author)

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

Tuchola County Broadband Network (TCBN)

DEFF Research Database (Denmark)

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

2012-01-01

In the paper the designing project (plan) of Tuchola City broadband IP optical network has been presented. The extended version of network plan constitute technical part of network Feasibility Study, that it is expected to be implemented in Tuchola and be financed from European Regional Development...... Funds. The network plan presented in the paper contains both topological structure of fiber optic network as well as the active equipment for the network. In the project described in the paper it has been suggested to use Modular Cable System - MCS for passive infrastructure and Metro Ethernet...

Manipulating the strength and broadband of the resonators in the terahertz metamaterials

Science.gov (United States)

Liu, Changxiang; Zhou, Qingli; Li, Chenyu; Zhang, Cunlin

2018-01-01

We investigate two dipoles which are attached or separated with the orthogonal arrangement in the terahertz frequency. These results show that the metasurface could achieve the resonance coupling and polarization conversion effect. There are two resonance dips in the transmission spectra, when these two dipoles are attached to form the L-shaped structure. With the spacing between vertical and horizontal dipoles separated, the broadband of the resonator becomes narrower and resonance dips merge into one deeper dip due to the superposition of the interaction of two dipoles. The loss of the energy is not only coupled to the free space but also converted to the cross-polarization. The broadband and the strength of the crosspolarization are modulated by changing the distance between the vertical and horizontal dipoles. Tuning the spacing, we control the co- and cross polarization of the broadband and the strength at the same time. This modulation provides the functionally potential applications in the terahertz modulators and filters.

Metamaterial-based half Maxwell fish-eye lens for broadband directive emissions

Science.gov (United States)

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

2013-01-01

The broadband directive emission from a metamaterial surface is numerically and experimentally reported. The metasurface, composed of non-resonant complementary closed ring structures, is designed to obey the refractive index of a half Maxwell fish-eye lens. A planar microstrip Vivaldi antenna is used as transverse magnetic polarized wave launcher for the lens. A prototype of the lens associated with its feed structure has been fabricated using standard lithography techniques. To experimentally demonstrate the broadband focusing properties and directive emissions, both the far-field radiation patterns and the near-field distributions have been measured. Measurements agree quantitatively and qualitatively with theoretical simulations.

Photonic crystal fiber design for broadband directional coupling

DEFF Research Database (Denmark)

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

2004-01-01

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

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...

Penetrating Shortwave Radiation and Sea Ice Algae feedbacks using the Community Earth System Model

Science.gov (United States)

Arntsen, A. E.; Perovich, D. K.; Bailey, D. A.; Holland, M. M.

2017-12-01

Transmittance of solar radiation through the sea ice cover determines energy transfer to the upper ocean in the form of heat as well as photosynthetically active radiation (PAR) available for the growth of under ice phytoplankton and bottom ice algal communities. A thinning ice cover, increased pond coverage, and earlier melt onset has increased light availability to the upper ocean in contemporary Arctic ice-covered waters. To investigate seasonal and spatial variability of solar shortwave irradiance penetrating the ice cover in the Beaufort and Chukchi Sea regions, we use the fully coupled Community Earth System Model (CESM) in conjunction with a multistream radiative transfer model constrained and initiated by in situ observations. Results inform the importance of light attenuation by ice-based algal pigments within large scale global climate models. We demonstrate the presence of bio-optical feedbacks related to a younger ice cover and examine how these relationships are impacting the trajectory of under ice blooms and the energy budget of the ice-ocean system.

The broadband spectral energy distributions of SDSS blazars

Science.gov (United States)

Li, Huai-Zhen; Chen, Luo-En; Jiang, Yun-Guo; Yi, Ting-Feng

2015-07-01

We compiled the radio, optical and X-ray data of blazars from the Sloan Digital Sky Survey database, and presented the distribution of luminosities and broadband spectral indices. The distribution of luminosities shows that the averaged luminosity of flat spectrum radio quasars (FSRQs) is larger than that of BL Lacertae (BL Lac) objects. On the other hand, the broadband spectral energy distribution reveals that FSRQs and low energy peaked BL Lac objects have similar spectral properties, but high energy peaked BL Lac objects have a distinct spectral property. This may be due to the fact that different subclasses of blazars have different intrinsic environments and are at different cooling levels. Even so, a unified scheme is also revealed from the color-color diagram, which hints that there are similar physical processes operating in all objects under a range of intrinsic physical conditions or beaming parameters. Supported by the National Natural Science Foundation of China.

A multievent study of broadband electrons observed by the DMSP satellites and their relation to red aurora observed at midlatitude stations

International Nuclear Information System (INIS)

Shiokawa, K.; Meng, C.; Reeves, G.D.; Rich, F.J.; Yumoto, K.

1997-01-01

Broadband electrons during magnetic storms are characterized by an unusually intense flux of precipitating electrons in the broadband energy range from 30 eV to 30 keV near the equatorward edge of the auroral oval (47 degree endash 66 degree magnetic latitude). Broadband electrons were first reported by Shiokawa et al. [1996]. In this paper, we report a multievent study of broadband electrons, using particle data obtained by the Defense Meteorological Satellite Program (DMSP) satellites during 23 magnetic storms from January 1989 through May 1992. Twelve broadband electron events are identified. Most of them are observed in the night sector, but some are observed in the morning sector. Particle data for successive polar passes of the DMSP multisatellites are used to show that broadband electrons generally last for less than 30 min and that for some events, they precipitate over a wide range of local times simultaneously. On the basis of a quantitative calculation of optical emissions from electrons in the neutral atmosphere, we conclude that broadband electrons are a possible cause of red auroras observed at midlatitude ground stations. We suggest that broadband electrons are associated with certain substorms during the main phase of magnetic storms. This conjecture comes from observations of H component positive bays and Pi 2 pulsations observed at low-latitude magnetic stations and from magnetic field variations observed at geosynchronous satellites. We conclude that the magnetospheric source of broadband electrons lies within the inner part of the plasma sheet. This conclusion is based on the facts that broadband electrons appear in latitudes where plasma sheet particles were observed before the event and that broadband electrons are observed poleward of the subauroral ion drifts, a position that corresponds to the inner edge of the injected particle layer during storms. (Abstract Truncated)

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.

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.

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.

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.

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

NARCIS (Netherlands)

Anonymous

2012-01-01

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

Beyond the Glow: Children's Broadband Access, Digital Learning Initiatives, and Academic Achievement in Rural Florida

Science.gov (United States)

Mardis, Marcia

2016-01-01

Approximately 26 million Americans have no access to broadband's social and economic benefits. A persistent level of non-adoption stems from adults' lack of perceived need or benefit. Florida's unique move to all digital instructional materials and required online learning by 2015 may make home broadband essential for maintaining a learning…

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

KAUST Repository

Zhang, Xueqian; Tian, Zhen; Yue, Weisheng; Gu, Jianqiang; Zhang, Shuang; Han, Jiaguang; Zhang, Weili

2013-01-01

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.

Analysis of technology and business antecedents for spectrum sharing in mobile broadband networks

OpenAIRE

Yrjölä, S. (Seppo)

2017-01-01

Abstract Sharing is emerging as one of the megatrends influencing future business opportunities, and wireless communications is no exception to this development. Future mobile broadband networks will operate on different types of spectrum bands including shared spectrum, which calls for changes in the operation and management of the networks. The creation and capture of value by the different players in the mobile broadband ecosystem is expected to change due to regulation, technology, an...

One goal, many paths: Policy proposals for universal access to broadband in Brazil

OpenAIRE

Gomes, André Moura; Cordeiro, Pedro Antero Braga; Araújo, Pedro Lucas da Cruz Pereira

2014-01-01

The purpose is to introduce policy proposals for universal access to broadband, assessing the hypothetical implementation of instruments suggested by the sectoral literature to Brazil. The methodology is based on the analysis of the literature on policies for universal access and broadband plans in the context of Latin America and the Organization for Economic Cooperation and Development (OECD) and the discussion of its effects on related sectoral indicators. Then, the impact of the applicati...

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.

75 FR 36071 - Framework for Broadband Internet Service

Science.gov (United States)

2010-06-24

... Internet service. Introduction 3. This Commission exists ``[f]or the purpose of regulating interstate and... news groups, the ability to create a personal Web page, and the ability to retrieve information from... broadband policies. 31. Some have suggested that although the D.C. Circuit rejected the Commission's theory...

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.

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.

Detector with internal gain for short-wave infrared ranging applications

Science.gov (United States)

Fathipour, Vala; Mohseni, Hooman

2017-09-01

Abstarct.Highly sensitive photon detectors are regarded as the key enabling elements in many applications. Due to the low photon energy at the short-wave infrared (SWIR), photon detection and imaging at this band are very challenging. As such, many efforts in photon detector research are directed toward improving the performance of the photon detectors operating in this wavelength range. To solve these problems, we have developed an electron-injection (EI) technique. The significance of this detection mechanism is that it can provide both high efficiency and high sensitivity at room temperature, a condition that is very difficult to achieve in conventional SWIR detectors. An EI detector offers an overall system-level sensitivity enhancement due to a feedback stabilized internal avalanche-free gain. Devices exhibit an excess noise of unity, operate in linear mode, require bias voltage of a few volts, and have a cutoff wavelength of 1700 nm. We review the material system, operating principle, and development of EI detectors. The shortcomings of the first-generation devices were addressed in the second-generation detectors. Measurement on second-generation devices showed a high-speed response of ˜6 ns rise time, low jitter of less than 20 ps, high amplification of more than 2000 (at optical power levels larger than a few nW), unity excess noise factor, and low leakage current (amplified dark current ˜10 nA at a bias voltage of -3 V and at room temperature. These characteristics make EI detectors a good candidate for high-resolution flash light detection and ranging (LiDAR) applications with millimeter scale depth resolution at longer ranges compared with conventional p-i-n diodes. Based on our experimentally measured device characteristics, we compare the performance of the EI detector with commercially available linear mode InGaAs avalanche photodiode (APD) as well as a p-i-n diode using a theoretical model. Flash LiDAR images obtained by our model show that the EI

76 FR 13769 - Rural Broadband Access Loans and Loan Guarantees

Science.gov (United States)

2011-03-14

... pharmacy work, and savings to health facilities from outsourcing specialized medical procedures. One study... international markets and enables new, small, and home-based businesses to thrive. Broadband access affords...

Nonlinear Analysis of Renal Autoregulation Under Broadband Forcing Conditions

DEFF Research Database (Denmark)

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

1994-01-01

Linear analysis of renal blood flow fluctuations, induced experimentally in rats by broad-band (pseudorandom) arterial blood pressure forcing at various power levels, has been unable to explain fully the dynamics of renal autoregulation at low frequencies. This observation has suggested...... the possibility of nonlinear mechanisms subserving renal autoregulation at frequencies below 0.2 Hz. This paper presents results of 3rd-order Volterra-Wiener analysis that appear to explain adequately the nonlinearities in the pressure-flow relation below 0.2 Hz in rats. The contribution of the 3rd-order kernel...... in describing the dynamic pressure-flow relation is found to be important. Furthermore, the dependence of 1st-order kernel waveforms on the power level of broadband pressure forcing indicates the presence of nonlinear feedback (of sigmoid type) based on previously reported analysis of a class of nonlinear...

A broadband Soleil–Babinet compensator for ultrashort light pulses

International Nuclear Information System (INIS)

Xu, Shixiang; Ma, Yingkun; Cai, Yi; Lu, Xiaowei; Zeng, Xuanke; Chen, Hongyi; Li, Jingzhen

2013-01-01

This letter reports a novel design for a broadband Soleil–Babinet compensator including two pairs of optical wedges plus one plate. According to our birefringent dispersion compensation model, we can eliminate the first-order birefringent phase retardation (BPR) dispersion by using three different birefringent crystals. Our results show a Soleil–Babinet compensator based on a MgF 2 /ADP/KDP combination can work from 0° to 360° phase compensation with the maximal residual BPR less than 6° within the spectral region from 0.65 to 0.95 μm. The residual BPR of the compensator increases monotonically with the spectral deviation from the designed central wavelength, so our compensator is very suitable to be used for broadband laser pulses with most of their energies around the central wavelengths. (letter)

A digital combining-weight estimation algorithm for broadband sources with the array feed compensation system

Science.gov (United States)

Vilnrotter, V. A.; Rodemich, E. R.

1994-01-01

An algorithm for estimating the optimum combining weights for the Ka-band (33.7-GHz) array feed compensation system was developed and analyzed. The input signal is assumed to be broadband radiation of thermal origin, generated by a distant radio source. Currently, seven video converters operating in conjunction with the real-time correlator are used to obtain these weight estimates. The algorithm described here requires only simple operations that can be implemented on a PC-based combining system, greatly reducing the amount of hardware. Therefore, system reliability and portability will be improved.

A New Empirical Model for Short-Term Forecasting of the Broadband Penetration: A Short Research in Greece

Directory of Open Access Journals (Sweden)

Salpasaranis Konstantinos

2011-01-01

Full Text Available The objective of this paper is to present a short research about the overall broadband penetration in Greece. In this research, a new empirical deterministic model is proposed for the short-term forecast of the cumulative broadband adoption. The fitting performance of the model is compared with some widely used diffusion models for the cumulative adoption of new telecommunication products, namely, Logistic, Gompertz, Flexible Logistic (FLOG, Box-Cox, Richards, and Bass models. The fitting process is done with broadband penetration official data for Greece. In conclusion, comparing these models with the empirical model, it could be argued that the latter yields well enough statistics indicators for fitting and forecasting performance. It also stresses the need for further research and performance analysis of the model in other more mature broadband markets.

Short-wave infrared barriode detectors using InGaAsSb absorption material lattice matched to GaSb

Energy Technology Data Exchange (ETDEWEB)

Craig, A. P.; Percy, B.; Marshall, A. R. J. [Physics Department, Lancaster University, Lancaster LA1 4YB (United Kingdom); Jain, M. [Amethyst Research Ltd., Kelvin Campus, West of Scotland Science Park, Glasgow G20 0SP (United Kingdom); Wicks, G.; Hossain, K. [Amethyst Research, Inc., 123 Case Circle, Ardmore, Oklahoma 73401 (United States); Golding, T. [Amethyst Research Ltd., Kelvin Campus, West of Scotland Science Park, Glasgow G20 0SP (United Kingdom); Amethyst Research, Inc., 123 Case Circle, Ardmore, Oklahoma 73401 (United States); McEwan, K.; Howle, C. [Defence Science and Technology Laboratory, Porton Down, Salisbury, Wiltshire SP4 0JQ (United Kingdom)

2015-05-18

Short-wave infrared barriode detectors were grown by molecular beam epitaxy. An absorption layer composition of In{sub 0.28}Ga{sub 0.72}As{sub 0.25}Sb{sub 0.75} allowed for lattice matching to GaSb and cut-off wavelengths of 2.9 μm at 250 K and 3.0 μm at room temperature. Arrhenius plots of the dark current density showed diffusion limited dark currents approaching those expected for optimized HgCdTe-based detectors. Specific detectivity figures of around 7×10{sup 10} Jones and 1×10{sup 10} Jones were calculated, for 240 K and room temperature, respectively. Significantly, these devices could support focal plane arrays working at higher operating temperatures.

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 househ...... 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....

Broadband Reflective Coating Process for Large FUVOIR Mirrors, Phase I

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+...

Optical cavity-assisted broadband optical transparency of a plasmonic metal film

International Nuclear Information System (INIS)

Liu, Zhengqi; Nie, Yiyou; Yuan, Wen; Liu, Xiaoshan; Huang, Shan; Gao, Huogui; Gu, Gang; Liu, Guiqiang; Chen, Jing

2015-01-01

We theoretically present a powerful method to achieve a continuous metal film structure with broadband optical transparency via introducing a dielectric Fabry–Pérot (FP) cavity. An incident optical field could be efficiently coupled and confined with the strong localized plasmons by the non-close-packed plasmonic crystal at the input part and could then become re-radiated output via the transmission channel supported by the dielectric cavity. The formed photonic-plasmonic system could therefore make the seamless metal film structure have a superior near-unity transparency (up to 97%) response and a broadband transparent spectrum with bandwidth >245 nm (with transmittance >90%) in the optical regime. The observed optical properties of the proposed structure can be highly tuned via varying the structural parameters. Based on the colloidal assembly method, the proposed plasmonic crystal can be fabricated in a large area. In addition, the achieved optical transparency can be retained in the extremely roughed metal film structure. Thereby, the findings could offer a feasible way to achieve a broadband transparent metal film structure and hold potential applications in transparent electrodes, touch screens and interactive electronics. (paper)

A novel approach for characterizing broad-band radio spectral energy distributions

Science.gov (United States)

Harvey, V. M.; Franzen, T.; Morgan, J.; Seymour, N.

2018-05-01

We present a new broad-band radio frequency catalogue across 0.12 GHz ≤ ν ≤ 20 GHz created by combining data from the Murchison Widefield Array Commissioning Survey, the Australia Telescope 20 GHz survey, and the literature. Our catalogue consists of 1285 sources limited by S20 GHz > 40 mJy at 5σ, and contains flux density measurements (or estimates) and uncertainties at 0.074, 0.080, 0.119, 0.150, 0.180, 0.408, 0.843, 1.4, 4.8, 8.6, and 20 GHz. We fit a second-order polynomial in log-log space to the spectral energy distributions of all these sources in order to characterize their broad-band emission. For the 994 sources that are well described by a linear or quadratic model we present a new diagnostic plot arranging sources by the linear and curvature terms. We demonstrate the advantages of such a plot over the traditional radio colour-colour diagram. We also present astrophysical descriptions of the sources found in each segment of this new parameter space and discuss the utility of these plots in the upcoming era of large area, deep, broad-band radio surveys.

Characterisation of optical filters for broadband UVA radiometer

Science.gov (United States)

Alves, Luciana C.; Coelho, Carla T.; Corrêa, Jaqueline S. P. M.; Menegotto, Thiago; Ferreira da Silva, Thiago; Aparecida de Souza, Muriel; Melo da Silva, Elisama; Simões de Lima, Maurício; Dornelles de Alvarenga, Ana Paula

2016-07-01

Optical filters were characterized in order to know its suitability for use in broadband UVA radiometer head for spectral irradiance measurements. The spectral transmittance, the angular dependence and the spatial uniformity of the spectral transmittance of the UVA optical filters were investigated. The temperature dependence of the transmittance was also studied.

Metallic stereostructured layer: An approach for broadband polarization state manipulation

International Nuclear Information System (INIS)

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

2014-01-01

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

An approach to the broadband effect on Latin American growth: A structural model

Directory of Open Access Journals (Sweden)

María Verónica Alderete

2017-07-01

Full Text Available This paper analyses the fixed broadband penetration effect on Latin American economic growth. The methodology employed consists of using a simultaneous equation model based on Koutroumpis (2009 and Katz and Callorda (2013. To aid this process, we use country level data from the World Bank and the Regional Dialogue about the Information Society-DIRSI for the 2010-2014 period. The results obtained stress the importance of broadband penetration for economic growth in Latin America.

Broadband and high-efficiency vortex beam generator based on a hybrid helix array.

Science.gov (United States)

Fang, Chaoqun; Wu, Chao; Gong, Zhijie; Zhao, Song; Sun, Anqi; Wei, Zeyong; Li, Hongqiang

2018-04-01

The vortex beam which carries the orbital angular momentum has versatile applications, such as high-resolution imaging, optical communications, and particle manipulation. Generating vortex beams with the Pancharatnam-Berry (PB) phase has drawn considerable attention for its unique spin-to-orbital conversion features. Despite the PB phase being frequency independent, an optical element with broadband high-efficiency circular polarization conversion feature is still needed for the broadband high-efficiency vortex beam generation. In this work, a broadband and high-efficiency vortex beam generator based on the PB phase is built with a hybrid helix array. Such devices can generate vortex beams with arbitrary topological charge. Moreover, vortex beams with opposite topological charge can be generated with an opposite handedness incident beam that propagates backward. The measured efficiency of our device is above 65% for a wide frequency range, with the relative bandwidth of 46.5%.

Broadband photonic crystal fiber coupler with polarization selection of coupling ratio

Science.gov (United States)

Jaroszewicz, Leszek R.; Stasiewicz, Karol A.; Marć, Paweł; Szymański, Michał

2010-09-01

In the paper a new broadband photonic crystal fiber coupler is presented. The proper application of the biconical taper technology has been used for manufacturing the coupler without air holes collapse in LMA10 fiber (NKT Photonics Crystal). This coupler, operates in the weakly coupling condition, protects coupling operation in range from 900 nm to 1700 nm. The coupling ratio between output arms is depending on wavelength and can be tuning by selection the proper input state of polarization. It gives opportunity to use the broadband crystal fiber coupler in many applications in which it is necessary to tune a coupling between output arms during the measurement.

Mission-Critical Mobile Broadband Communications in Open Pit Mines

DEFF Research Database (Denmark)

Uzeda Garcia, Luis Guilherme; Portela Lopes de Almeida, Erika; Barbosa, Viviane S. B.

2016-01-01

that need to be met by the wireless network. This article introduces fundamental concepts behind open-pit mining and discusses why this ever changing environment coupled with strict industrial reliability requirements pose unique challenges to traditional broadband network planning and optimization...

Will they fly? : PPPs and the ultrafast broadband initiative

NARCIS (Netherlands)

Sadowski, B.M.; Howell, B.

2012-01-01

The political perception of New Zealand's broadband market performance as ‘poor' has underpinned many significant changes to the telecommunications policy and regulatory environments since 2001. Most recently, this has been manifested in substantial government subsidies by way of public-private

78 FR 8353 - Rural Broadband Access Loans and Loan Guarantees

Science.gov (United States)

2013-02-06

... outsourcing specialized medical procedures. One study of 24 rural hospitals placed the annual cost of not... a key to economic growth. For rural businesses, broadband gives access to national and international...

"Radiative Closure Studies for Clear Skies During the ARM 2003 Aerosol Intensive Observation Period"

Energy Technology Data Exchange (ETDEWEB)

J. J. Michalsky, G. P. Anderson, J. Barnard, J. Delamere, C. Gueymard, S. Kato, P. Kiedron, A. McComiskey, and P. Ricchiazzi

2006-04-01

The Department of Energy's Atmospheric Radiation Measurement (ARM) program sponsored a large intensive observation period (IOP) to study aerosol during the month of May 2003 around the Southern Great Plains (SGP) Climate Research Facility (CRF) in north central Oklahoma. Redundant measurements of aerosol optical properties were made using different techniques at the surface as well as in vertical profile with sensors aboard two aircraft. One of the principal motivations for this experiment was to resolve the disagreement between models and measurements of diffuse horizontal broadband shortwave irradiance at the surface, especially for modest aerosol loading. This paper focuses on using the redundant aerosol and radiation measurements during this IOP to compare direct beam and diffuse horizontal broadband shortwave irradiance measurements and models at the surface for a wide range of aerosol cases that occurred during 30 clear-sky periods on 13 days of May 2003. Models and measurements are compared over a large range of solar-zenith angles. Six different models are used to assess the relative agreement among them and the measurements. Better agreement than previously achieved appears to be the result of better specification of input parameters and better measurements of irradiances than in prior studies. Biases between modeled and measured direct irradiances are less than 1%, and biases between modeled and measured diffuse irradiances are less than 2%.

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% ...

Multiphase lattice Boltzmann on the Cell Broadband Engine

International Nuclear Information System (INIS)

Belletti, F.; Mantovani, F.; Tripiccione, R.; Biferale, L.; Schifano, S.F.; Toschi, F.

2009-01-01

Computational experiments are one of the most used and flexible investigation tools in fluid dynamics. The Lattice Boltzmann Equation is a well established computational method particularly promising for multi-phase flows at micro and macro scales. Here we present preliminary results on performances of the Lbe method on the Cell Broadband Engine platform.

Evaluation of reproductive function of female rats exposed to radiofrequency fields (27. 12 MHz) near a shortwave diathermy device

Energy Technology Data Exchange (ETDEWEB)

Brown-Woodman, P.D.; Hadley, J.A.; Richardson, L.; Bright, D.; Porter, D.

1989-04-01

In recent years, there has been increased concern regarding effects of operator exposure to the electromagnetic (EM) field associated with shortwave diathermy devices. The present study was designed to investigate the effects, on rats, of repeated exposure to such an EM field. Following repeated exposure for 5 wk, a reduction in fertility occurred as indicated by a reduced number of matings in exposed rats compared to sham-irradiated rats and a reduction in the number of rats that conceived after mating. The data suggest that female operators could experience reduced fertility, if they remained close to the console for prolonged periods. This has particular significant for the physiotherapy profession.

Radio over fiber transceiver employing phase modulation of an optical broadband source.

Science.gov (United States)

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

2010-10-11

This paper proposes a low-cost RoF transceiver for multichannel SCM/WDM signal distribution suitable for future broadband access networks. The transceiver is based on the phase modulation of an optical broadband source centered at third transmission window. Prior to phase modulation the optical broadband source output signal is launched into a Mach-Zehnder interferometer structure, as key device enabling radio signals propagation over the optical link. Furthermore, an optical CWDM is employed to create a multichannel scenario by performing the spectral slicing of the modulated optical signal into a number of channels each one conveying the information from the central office to different base stations. The operation range is up to 20 GHz with a modulation bandwidth around of 500 MHz. Experimental results of the transmission of SCM QPSK and 64-QAM data through 20 Km of SMF exhibit good EVM results in the operative range determined by the phase-to-intensity conversion process. The proposed approach shows a great suitability for WDM networks based on RoF signal transport and also represents a cost-effective solution for passive optical networks.

Design of a miniaturized integrated spectrometer for spectral tissue sensing

Science.gov (United States)

Belay, Gebirie Yizengaw; Hoving, Willem; Ottevaere, Heidi; van der Put, Arthur; Weltjens, Wim; Thienpont, Hugo

2016-04-01

Minimally-invasive image-guided procedures become increasingly used by physicians to obtain real-time characterization feedback from the tissue at the tip of their interventional device (needle, catheter, endoscopic or laparoscopic probes, etc…) which can significantly improve the outcome of diagnosis and treatment, and ultimately reduce cost of the medical treatment. Spectral tissue sensing using compact photonic probes has the potential to be a valuable tool for screening and diagnostic purposes, e.g. for discriminating between healthy and tumorous tissue. However, this technique requires a low-cost broadband miniature spectrometer so that it is commercially viable for screening at point-of-care locations such as physicians' offices and outpatient centers. Our goal is therefore to develop a miniaturized spectrometer based on diffractive optics that combines the functionalities of a visible/near-infrared (VIS/NIR) and shortwave-infrared (SWIR) spectrometer in one very compact housing. A second goal is that the hardware can be produced in high volume at low cost without expensive time consuming alignment and calibration steps. We have designed a miniaturized spectrometer which operates both in the visible/near-infrared and shortwave-infrared wavelength regions ranging from 400 nm to 1700 nm. The visible/near-infrared part of the spectrometer is designed for wavelengths from 400 nm to 800 nm whereas the shortwave-infrared segment ranges from 850 nm to 1700 nm. The spectrometer has a resolution of 6 nm in the visible/near-infrared wavelength region and 10 nm in the shortwave-infrared. The minimum SNR of the spectrometer for the intended application is about 151 in the VIS/NIR range and 6000 for SWIR. In this paper, the modelling and design, and power budget analysis of the miniaturized spectrometer are presented. Our work opens a door for future affordable micro- spectrometers which can be integrated with smartphones and tablets, and used for point

Single-component supported lipid bilayers probed using broadband nonlinear optics.

Science.gov (United States)

Olenick, Laura L; Chase, Hilary M; Fu, Li; Zhang, Yun; McGeachy, Alicia C; Dogangun, Merve; Walter, Stephanie R; Wang, Hong-Fei; Geiger, Franz M

2018-01-31

Broadband SFG spectroscopy is shown to offer considerable advantages over scanning systems in terms of signal-to-noise ratios when probing well-formed single-component supported lipid bilayers formed from zwitterionic lipids with PC headgroups. The SFG spectra obtained from bilayers formed from DOPC, POPC, DLPC, DMPC, DPPC and DSPC show a common peak at ∼2980 cm -1 , which is subject to interference between the C-H and the O-H stretches from the aqueous phase, while membranes having transition temperatures above the laboratory temperature produce SFG spectra with at least two additional peaks, one at ∼2920 cm -1 and another at ∼2880 cm -1 . The results validate spectroscopic and structural data from SFG experiments utilizing asymmetric bilayers in which one leaflet differs from the other in the extent of deuteration. Differences in H 2 O-D 2 O exchange experiments reveal that the lineshapes of the broadband SFG spectra are significantly influenced by interference from OH oscillators in the aqueous phase, even when those oscillators are not probed by the incident infrared light in our broadband setup. In the absence of spectral interference from the OH stretches of the solvent, the alkyl chain terminal methyl group of the bilayer is found to be tilted at an angle of 15° to 35° from the surface normal.

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.

Development of multilayer optics for X-ray broadband spectrometry of plasma emission

International Nuclear Information System (INIS)

Emprin, Benoit

2014-01-01

Within the framework of the research on inertial confinement fusion, the 'Commissariat a l'energie atomique et aux energies alternatives' has studied and implemented an absolute calibrated time-Resolved broadband soft x-Ray spectrometer, called 'Diagnostic de Mesure du rayonnement X'. This diagnostic, composed of 20 measurement channels, measures the emitted radiant power from a laser created plasma in the range from 50 eV to 20 keV. We have developed additional measurement channels to obtain redundancy and an improvement in measurement accuracy. The principle of these new channels is based on an original concept to obtain spectral bounded flat-Responses. Two channels have been developed for the 2 - 4 keV and 4 - 6 keV spectral ranges, using aperiodic multilayer mirrors made at the 'Laboratoire Charles Fabry' with Cr/Sc and Ni/W/SiC/W layers respectively. These mirrors were characterized at synchrotron radiation facilities and integrated into the spectrometer. The two new channels were used during laser-Plasma experimental campaigns at the OMEGA laser facility in Rochester (USA). This allowed us to determine directly the radiant power with only one measurement within a certain spectral band, and with a better precision when compared with using standard channels. The results, in good agreement with the standard measurement channels, allowed us to validate the use of aperiodic multilayer mirrors for X-Ray broadband spectrometry. (author) [fr

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.

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.

Prediction and measurement of the electromagnetic environment of high-power medium-wave and short-wave broadcast antennas in far field.

Science.gov (United States)

Tang, Zhanghong; Wang, Qun; Ji, Zhijiang; Shi, Meiwu; Hou, Guoyan; Tan, Danjun; Wang, Pengqi; Qiu, Xianbo

2014-12-01

With the increasing city size, high-power electromagnetic radiation devices such as high-power medium-wave (MW) and short-wave (SW) antennas have been inevitably getting closer and closer to buildings, which resulted in the pollution of indoor electromagnetic radiation becoming worsened. To avoid such radiation exceeding the exposure limits by national standards, it is necessary to predict and survey the electromagnetic radiation by MW and SW antennas before constructing the buildings. In this paper, a modified prediction method for the far-field electromagnetic radiation is proposed and successfully applied to predict the electromagnetic environment of an area close to a group of typical high-power MW and SW wave antennas. Different from currently used simplified prediction method defined in the Radiation Protection Management Guidelines (H J/T 10. 3-1996), the new method in this article makes use of more information such as antennas' patterns to predict the electromagnetic environment. Therefore, it improves the prediction accuracy significantly by the new feature of resolution at different directions. At the end of this article, a comparison between the prediction data and the measured results is given to demonstrate the effectiveness of the proposed new method. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Relation between seasonally detrended shortwave infrared reflectance data and land surface moisture in semi-arid Sahel

DEFF Research Database (Denmark)

Olsen, Jørgen Lundegaard; Ceccato, Pietro; Proud, Simon Richard

2013-01-01

in vegetation moisture status, and is compared to detrended time series of the Normalized Difference Vegetation Index (NDVI). It was found that when plant available water is low, the SIWSI anomalies increase over time, while the NDVI anomalies decrease over time, but less systematically. Therefore SIWSI may......In the Sudano-Sahelian areas of Africa droughts can have serious impacts on natural resources, and therefore land surface moisture is an important factor. Insufficient conventional sites for monitoring land surface moisture make the use of Earth Observation data for this purpose a key issue...... Second Generation (MSG) satellite. We focused on responses in surface reflectance to soil- and surface moisture for bare soil and early to mid- growing season. A method for implementing detrended time series of the Shortwave Infrared Water Stress Index (SIWSI) is examined for detecting variations...

Calibration of EFOSC2 Broadband Linear Imaging Polarimetry

Science.gov (United States)

Wiersema, K.; Higgins, A. B.; Covino, S.; Starling, R. L. C.

2018-03-01

The European Southern Observatory Faint Object Spectrograph and Camera v2 is one of the workhorse instruments on ESO's New Technology Telescope, and is one of the most popular instruments at La Silla observatory. It is mounted at a Nasmyth focus, and therefore exhibits strong, wavelength and pointing-direction-dependent instrumental polarisation. In this document, we describe our efforts to calibrate the broadband imaging polarimetry mode, and provide a calibration for broadband B, V, and R filters to a level that satisfies most use cases (i.e. polarimetric calibration uncertainty 0.1%). We make our calibration codes public. This calibration effort can be used to enhance the yield of future polarimetric programmes with the European Southern Observatory Faint Object Spectrograph and Camera v2, by allowing good calibration with a greatly reduced number of standard star observations. Similarly, our calibration model can be combined with archival calibration observations to post-process data taken in past years, to form the European Southern Observatory Faint Object Spectrograph and Camera v2 legacy archive with substantial scientific potential.

Broadband Electrophysiological Dynamics Contribute to Global Resting-State fMRI Signal.

Science.gov (United States)

Wen, Haiguang; Liu, Zhongming

2016-06-01

Spontaneous activity observed with resting-state fMRI is used widely to uncover the brain's intrinsic functional networks in health and disease. Although many networks appear modular and specific, global and nonspecific fMRI fluctuations also exist and both pose a challenge and present an opportunity for characterizing and understanding brain networks. Here, we used a multimodal approach to investigate the neural correlates to the global fMRI signal in the resting state. Like fMRI, resting-state power fluctuations of broadband and arrhythmic, or scale-free, macaque electrocorticography and human magnetoencephalography activity were correlated globally. The power fluctuations of scale-free human electroencephalography (EEG) were coupled with the global component of simultaneously acquired resting-state fMRI, with the global hemodynamic change lagging the broadband spectral change of EEG by ∼5 s. The levels of global and nonspecific fluctuation and synchronization in scale-free population activity also varied across and depended on arousal states. Together, these results suggest that the neural origin of global resting-state fMRI activity is the broadband power fluctuation in scale-free population activity observable with macroscopic electrical or magnetic recordings. Moreover, the global fluctuation in neurophysiological and hemodynamic activity is likely modulated through diffuse neuromodulation pathways that govern arousal states and vigilance levels. This study provides new insights into the neural origin of resting-state fMRI. Results demonstrate that the broadband power fluctuation of scale-free electrophysiology is globally synchronized and directly coupled with the global component of spontaneous fMRI signals, in contrast to modularly synchronized fluctuations in oscillatory neural activity. These findings lead to a new hypothesis that scale-free and oscillatory neural processes account for global and modular patterns of functional connectivity observed

Locating and Quantifying Broadband Fan Sources Using In-Duct Microphones

Science.gov (United States)

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

2010-01-01

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

Multicomponent gas analysis using broadband quantum cascade laser spectroscopy

NARCIS (Netherlands)

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

2014-01-01

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

Unbundling in Current Broadband and Next-Generation Ultra-Broadband Access Networks

Science.gov (United States)

Gaudino, Roberto; Giuliano, Romeo; Mazzenga, Franco; Valcarenghi, Luca; Vatalaro, Francesco

2014-05-01

This article overviews the methods that are currently under investigation for implementing multi-operator open-access/shared-access techniques in next-generation access ultra-broadband architectures, starting from the traditional "unbundling-of-the-local-loop" techniques implemented in legacy twisted-pair digital subscriber line access networks. A straightforward replication of these copper-based unbundling-of-the-local-loop techniques is usually not feasible on next-generation access networks, including fiber-to-the-home point-to-multipoint passive optical networks. To investigate this issue, the article first gives a concise description of traditional copper-based unbundling-of-the-local-loop solutions, then focalizes on both next-generation access hybrid fiber-copper digital subscriber line fiber-to-the-cabinet scenarios and on fiber to the home by accounting for the mix of regulatory and technological reasons driving the next-generation access migration path, focusing mostly on the European situation.

Design of a broadband ultra-large area acoustic cloak based on a fluid medium

Science.gov (United States)

Zhu, Jian; Chen, Tianning; Liang, Qingxuan; Wang, Xiaopeng; Jiang, Ping

2014-10-01

A broadband ultra-large area acoustic cloak based on fluid medium was designed and numerically implemented with homogeneous metamaterials according to the transformation acoustics. In the present work, fluid medium as the body of the inclusion could be tuned by changing the fluid to satisfy the variant acoustic parameters instead of redesign the whole cloak. The effective density and bulk modulus of the composite materials were designed to agree with the parameters calculated from the coordinate transformation methodology by using the effective medium theory. Numerical simulation results showed that the sound propagation and scattering signature could be controlled in the broadband ultra-large area acoustic invisibility cloak, and good cloaking performance has been achieved and physically realized with homogeneous materials. The broadband ultra-large area acoustic cloaking properties have demonstrated great potentials in the promotion of the practical applications of acoustic cloak.

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.

A Broadband Metasurface-Based Terahertz Flat-Lens Array

KAUST Repository

Wang, Qiu; Zhang, Xueqian; Xu, Yuehong; Tian, Zhen; Gu, Jianqiang; Yue, Weisheng; Zhang, Shuang; Han, Jiaguang; Zhang, Weili; Zhang, Weili

2015-01-01

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.

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.

Resource Management in Broadband Communication Networks

DEFF Research Database (Denmark)

Hansen, Mads Stenhuus

2003-01-01

. 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......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...

Fiber-based broadband black-light source

OpenAIRE

Sylvestre , Thibaut; Lee , Min Won; Ragueh , A. R.; Stiller , Birgit; Fanjoux , Gil; Barviau , B.; Mussot , A.; Kudlinski , A.

2012-01-01

International audience; Black-Light or Wood's lamp refers to sources that emit long-wavelength ultraviolet radiation (UV-A) from 315 nm and little visible light till 410 nm (blue). In this paper, we present a new fibre-based source of "black light", a source that emits broadband ultraviolet radiation but only small amounts of visible light and no infrared light. We made this source by pumping a specially designed silica photonic crystal fibre (PCF) with 355 nm light pulses from a Q-switched f...

Estimation of chromatic errors from broadband images for high contrast imaging

Science.gov (United States)

Sirbu, Dan; Belikov, Ruslan

2015-09-01

Usage of an internal coronagraph with an adaptive optical system for wavefront correction for direct imaging of exoplanets is currently being considered for many mission concepts, including as an instrument addition to the WFIRST-AFTA mission to follow the James Web Space Telescope. The main technical challenge associated with direct imaging of exoplanets with an internal coronagraph is to effectively control both the diffraction and scattered light from the star so that the dim planetary companion can be seen. For the deformable mirror (DM) to recover a dark hole region with sufficiently high contrast in the image plane, wavefront errors are usually estimated using probes on the DM. To date, most broadband lab demonstrations use narrowband filters to estimate the chromaticity of the wavefront error, but this reduces the photon flux per filter and requires a filter system. Here, we propose a method to estimate the chromaticity of wavefront errors using only a broadband image. This is achieved by using special DM probes that have sufficient chromatic diversity. As a case example, we simulate the retrieval of the spectrum of the central wavelength from broadband images for a simple shaped- pupil coronagraph with a conjugate DM and compute the resulting estimation error.

Optimization of Broadband Seismic Network in the Kingdom of Saudi Arabia

KAUST Repository

Alshuhail, Abdulrahman

2011-05-01

Saudi Arabia covers a large portion of the Arabian plate, a region characterized by seismic activity, along complex divergent and convergent plate boundaries. In order to understand these plate boundaries it is essential to optimize the design of the broadband seismic station network to accurately locate earthquakes. In my study, I apply an optimization method to design the broadband station distribution in Saudi Arabia. This method is based on so called D-optimal planning criterion that optimizes the station distribution for locating the hypocenters of earthquakes. Two additional adjustments were implemented: to preferentially acquire direct and refracted wave, and to account for geometric spreading of seismic waves (and thus increases the signal to noise ratio). The method developed in this study for optimizing the geographical location of broadband stations uses the probability of earthquake occurrence and a 1-D velocity model of the region, and minimizes the ellipsoid volume of the earthquake location errors. The algorithm was applied to the current seismic network, operated by the Saudi Geologic Survey (SGS). Based on the results, I am able to make recommendations on, how to expand the existing network. Furthermore, I quantify the efficiency of our method by computing the standard error of epicenter and depth before and after adding the proposed stations.

Expressive Communication and Human Development in the New Broadband Environment

Science.gov (United States)

Carey, John

2004-01-01

An understanding of the structure and functions of expressive communication in face-to-face communication and audiovisual media can inform the development of new educational services for human development across cultures in the emerging broadband environment.

Sensitivity improvement for correlations involving arginine side-chain N{epsilon}/H{epsilon} resonances in multi-dimensional NMR experiments using broadband {sup 15}N 180{sup o} pulses

Energy Technology Data Exchange (ETDEWEB)

Iwahara, Junji; Clore, G. Marius [National Institutes of Health, Laboratory of Chemical Physics, Building 5, National Institute of Diabetes and Digestive and Kidney Disease (United States)], E-mail: mariusc@intra.niddk.nih.gov

2006-12-15

Due to practical limitations in available {sup 15}N rf field strength, imperfections in {sup 15}N 180{sup o} pulses arising from off-resonance effects can result in significant sensitivity loss, even if the chemical shift offset is relatively small. Indeed, in multi-dimensional NMR experiments optimized for protein backbone amide groups, cross-peaks arising from the Arg guanidino {sup 15}N{epsilon} ({approx}85 ppm) are highly attenuated by the presence of multiple INEPT transfer steps. To improve the sensitivity for correlations involving Arg N{epsilon}-H{epsilon} groups, we have incorporated {sup 15}N broadband 180 deg. pulses into 3D {sup 15}N-separated NOE-HSQC and HNCACB experiments. Two {sup 15}N-WURST pulses incorporated at the INEPT transfer steps of the 3D {sup 15}N-separated NOE-HSQC pulse sequence resulted in a {approx}1.5-fold increase in sensitivity for the Arg N{epsilon}-H{epsilon} signals at 800 MHz. For the 3D HNCACB experiment, five {sup 15}N Abramovich-Vega pulses were incorporated for broadband inversion and refocusing, and the sensitivity of Arg{sup 1}H{epsilon}-{sup 15}N{epsilon}-{sup 13}C{gamma}/{sup 13}C{delta} correlation peaks was enhanced by a factor of {approx}1.7 at 500 MHz. These experiments eliminate the necessity for additional experiments to assign Arg {sup 1}H{epsilon} and {sup 15}N{epsilon} resonances. In addition, the increased sensitivity afforded for the detection of NOE cross-peaks involving correlations with the {sup 15}N{epsilon}/{sup 1}H{epsilon} of Arg in 3D {sup 15}N-separated NOE experiments should prove to be very useful for structural analysis of interactions involving Arg side-chains.

77 FR 3635 - Connect America Fund; A National Broadband Plan for Our Future; Establishing Just and Reasonable...

Science.gov (United States)

2012-01-25

...-208; Report No. 2945] Connect America Fund; A National Broadband Plan for Our Future; Establishing Just and Reasonable Rates for Local Exchange Carriers; High-Cost Universal Service Support et al... applicability. Subject: Connect America Fund: A National Broadband Plan for Our Future; Establishing Just and...

Detection in shallow water using broadband-DORT

Science.gov (United States)

Fromm, David M.; Gaumond, Charles F.; Lingevitch, Joseph F.; Gauss, Roger C.; Menis, Richard

2003-10-01

The decomposition of the time-reversal operator (DORT) [Prada et al., J. Acoust. Soc. Am. 99, 2067-2076 (1996)] has been extended into a coherent, broadband method. Broadband DORT has also been shown to isolate resolvable scatterers at various depths and ranges in a bistatic, active sonar in shallow water. Results are shown from the application of DORT to sea data taken in an area south of Hudson Canyon off the New Jersey coast during Geoclutter II. The vertical source/receiver array with 56 hydrophones spanning the water column was operated between 3.0 and 3.5 kHz. The elements were divided into four groups, with each group acting as a coherent, broadside source. Two methods were used for exciting the separate channels. One method was the use of subsequent LFMs and the other was the use of simultaneous transmission of four pseudorandom-noise signals. The target was a midwater column echo-repeater. Results are compared with modeling based on in situ environmental measurements during the experiment. [The authors acknowledge signal-processing expertise from Dr. Ning Xiang, University of Mississippi, and ENS Alan Meyer, LLNL, support from Dr. Jeff Simmen, ONR, and assistance from Dr. Charles Holland, ARL/PSU. Work supported by ONR.

Broadband acoustic properties of a murine skull.

Science.gov (United States)

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

2016-03-07

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

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.

Silicon-on-insulator-based polarization-independent 1×3 broadband beam splitter with adiabatic coupling

Science.gov (United States)

Gong, Yuanhao; Liu, Lei; Chang, Limin; Li, Zhiyong; Tan, Manqing; Yu, Yude

2017-10-01

We propose and numerically simulate a polarization-independent 1×3 broadband beam splitter based on silicon-on-insulator (SOI) technology with adiabatic coupling. The designed structure is simulated by beam-propagation-method (BPM) and gets simulated transmission uniformity of three outputs better than 0.3dB for TE-polarization and 0.8dB for TM-polarization in a broadband of 180nm.

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

DEFF Research Database (Denmark)

Canning, John; Skivesen, Nina; Kristensen, Martin

2007-01-01

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

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.

Broadband demonstrations of true-time delay using linear sideband chirped programming and optical coherent transients

International Nuclear Information System (INIS)

Reibel, R.R.; Barber, Z.W.; Fischer, J.A.; Tian, M.; Babbitt, W.R.

2004-01-01

Linear sideband chirped (LSC) programming is introduced as a means of configuring spatial-spectral holographic gratings for optical coherent transient processors. Similar to linear frequency chirped programming, LSC programming allows the use of broadband integrated electro-optic phase modulators to produce chirps instead of using elaborate broadband chirped lasers. This approach has several advantages including the ability to use a stabilized laser for the optical carrier as well as stable, reproducible chirped optical signals when the modulator is driven digitally. Using LSC programming, we experimentally demonstrate broadband true-time delay as a proof of principle for the optical control of phased array radars. Here both cw phase modulated and binary phase shift keyed probe signals are true-time delayed with bandwidths of 1 GHz and delay resolutions better than 60 ps

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...

Fast elliptic-curve cryptography on the Cell Broadband Engine

NARCIS (Netherlands)

Costigan, N.; Schwabe, P.; Preneel, B.

2009-01-01

This paper is the first to investigate the power of the Cell Broadband Engine for state-of-the-art public-key cryptography. We present a high-speed implementation of elliptic-curve Diffie-Hellman (ECDH) key exchange for this processor, which needs 697080 cycles on one Synergistic Processor Unit for

Enhanced Solar-to-Hydrogen Generation with Broadband Epsilon-Near-Zero Nanostructured Photocatalysts

KAUST Repository

Tian, Yi

2017-05-08

The direct conversion of solar energy into fuels or feedstock is an attractive approach to address increasing demand of renewable energy sources. Photocatalytic systems relying on the direct photoexcitation of metals have been explored to this end, a strategy that exploits the decay of plasmonic resonances into hot carriers. An efficient hot carrier generation and collection requires, ideally, their generation to be enclosed within few tens of nanometers at the metal interface, but it is challenging to achieve this across the broadband solar spectrum. Here the authors demonstrate a new photocatalyst for hydrogen evolution based on metal epsilon-near-zero metamaterials. The authors have designed these to achieve broadband strong light confinement at the metal interface across the entire solar spectrum. Using electron energy loss spectroscopy, the authors prove that hot carriers are generated in a broadband fashion within 10 nm in this system. The resulting photocatalyst achieves a hydrogen production rate of 9.5 µmol h-1  cm-2 that exceeds, by a factor of 3.2, that of the best previously reported plasmonic-based photocatalysts for the dissociation of H2 with 50 h stable operation.

A broadband damper design inspired by cartilage-like relaxation mechanisms

Science.gov (United States)

Liu, Lejie; Usta, Ahmet D.; Eriten, Melih

2017-10-01

In this study, we introduce a broadband damper design inspired by the cartilage-like relaxation mechanisms. In particular, we study broadband (static to 10 kHz) dissipative properties of model cartilage systems by probe-based static and dynamic indentation, and validate that fractional Zener models can simulate the empirical data up to a desirable accuracy within the frequency range of interest. Utilizing these observations, we design a composite damper design where a poroelastic layer is sandwiched between two hard materials, and load transfer occurs across interfaces with multiple length scales. Modeling those interfaces with fractional Zener elements in parallel configuration, and manipulating the distribution of the Zener elements across different peak relaxation frequencies, we obtain a relatively constant loss factor within an unprecedented frequency range (3-3 kHz). We also discuss how these findings can be employed in a practical damping design.

Broadband semiconductor optical amplifiers of the spectral range 750 – 1100 nm

International Nuclear Information System (INIS)

Andreeva, E V; Il'chenko, S N; Lobintsov, A A; Shramenko, M V; Ladugin, M A; Marmalyuk, A A; Yakubovich, S D

2013-01-01

A line of travelling-wave semiconductor optical amplifiers (SOAs) based on heterostructures used for production of broadband superluminescent diodes is developed. The pure small-signal gains of the developed SOA modules are about 25 dB, while the gain bandwidths at a level of –10 dB reach 50 – 100 nm. As a whole, the SOA modules cover the IR spectral range from 750 to 1100 nm. The SOAs demonstrate a high reliability at a single-mode fibre-coupled cw output power up to 50 mW. Examples of application of two of the developed SOA modules as active elements of broadband fast-tunable lasers are presented. (lasers)

Broadband semiconductor optical amplifiers of the spectral range 750 – 1100 nm

Energy Technology Data Exchange (ETDEWEB)

Andreeva, E V; Il' chenko, S N; Lobintsov, A A; Shramenko, M V [Superlum Diodes Ltd., Moscow (Russian Federation); Ladugin, M A [' Sigm Plyus' Ltd, Moscow (Russian Federation); Marmalyuk, A A [Open Joint-Stock Company M.F. Stel' makh Polyus Research Institute, Moscow (Russian Federation); Yakubovich, S D [Moscow State Institute of Radio-Engineering, Electronics and Automation (Technical University), Moscow (Russian Federation)

2013-11-30

A line of travelling-wave semiconductor optical amplifiers (SOAs) based on heterostructures used for production of broadband superluminescent diodes is developed. The pure small-signal gains of the developed SOA modules are about 25 dB, while the gain bandwidths at a level of –10 dB reach 50 – 100 nm. As a whole, the SOA modules cover the IR spectral range from 750 to 1100 nm. The SOAs demonstrate a high reliability at a single-mode fibre-coupled cw output power up to 50 mW. Examples of application of two of the developed SOA modules as active elements of broadband fast-tunable lasers are presented. (lasers)

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

Broad-band time-resolved near infrared spectroscopy in the TJ-II stellarator

Energy Technology Data Exchange (ETDEWEB)

Rodriguez, M.C.; Pastor, I.; Cal, E. de la; McCarthy, K.J. [Laboratorio Nacional de Fusion, CIEMAT, Madrid (Spain); Diaz, D. [Universidad Autonoma de Madrid, Dept Quimica Fisica Aplicada, Madrid (Spain)

2014-11-15

First experimental results on broad-band, time-resolved Near Infrared (NIR;here loosely defined as covering from 750 to 1650 nm) passive spectroscopy using a high sensitivity InGaAs detector are reported for the TJ-II Stellarator. Experimental set-up is described together with its main characteristics, the most remarkable ones being its enhanced NIR response, broadband spectrum acquisition in a single shot, and time-resolved measurements with up to 1.8 kHz spectral rate. Prospects for future work and more extended physics studies in this newly open spectral region in TJ-II are discussed. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

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.

Broadband giant-refractive-index material based on mesoscopic space-filling curves

Science.gov (United States)

Chang, Taeyong; Kim, Jong Uk; Kang, Seung Kyu; Kim, Hyowook; Kim, Do Kyung; Lee, Yong-Hee; Shin, Jonghwa

2016-08-01

The refractive index is the fundamental property of all optical materials and dictates Snell's law, propagation speed, wavelength, diffraction, energy density, absorption and emission of light in materials. Experimentally realized broadband refractive indices remain 1,800 resulting from a mesoscopic crystal with a dielectric constant greater than three million. This gigantic enhancement effect originates from the space-filling curve concept from mathematics. The principle is inherently very broad band, the enhancement being nearly constant from zero up to the frequency of interest. This broadband giant-refractive-index medium promises not only enhanced resolution in imaging and raised fundamental absorption limits in solar energy devices, but also compact, power-efficient components for optical communication and increased performance in many other applications.

Nitrogen deficiency detection using reflected shortwave radiation from irrigated corn canopies

International Nuclear Information System (INIS)

Blackmer, T.M.; Schepers, J.S.; Varvel, G.E.; Walter-Shea, E.A.

1996-01-01

Techniques that measure the N status of corn (Zea mays L.) can aid in management decisions that have economic and environmental implications. This study was conducted to identify reflected electromagnetic wavelengths most sensitive to detecting N deficiencies in a corn canopy with the possibility for use as a management tool. Reflected shortwave radiation was measured from an irrigated corn N response trial with four hybrids and five N rates at 0, 40, 80, 120, and 160 kg N ha -1 in 1992 and 0, 50, 100, 150, and 200 kg N ha -1 in 1993. A portable spectroradiometer was used to measure reflected radiation (400-1100 nm in 1992, 350-1050 nm in 1993) from corn canopies at approximately the R5 growth stage. Regression analyses revealed that reflected radiation near 550 and 710 nm was superior to reflected radiation near 450 or 650 nm for detecting N deficiencies. The ratio of light reflectance between 550 and 600 nm to light reflectance between 800 and 900 nm also provided sensitive detection of N stress. In 1993, an inexpensive photometric cell, which has peak sensitivity to light centered at 550 nm, was also used to measure reflected radiation from a corn canopy. Photometric cell readings correlated with relative grain yield (P < 0.001, r 2 = 0.74), but more research will be required to develop procedures to account for varying daylight conditions. These results provide information needed for the development of variable-rate fertilizer N application technology. (author)

Compositional Variations in Sands of the Bagnold Dunes, Gale Crater, Mars, from Visible-Shortwave Infrared Spectroscopy and Comparison to Ground-Truth from the Curiosity Rover

OpenAIRE

Lapotre, M. G. A.; Ehlmann, B. L.; Minson, S. E.; Arvidson, R. E.; Ayoub, F.; Fraeman, A. A.; Ewing, R. C.; Bridges, N. T.

2017-01-01

During its ascent up Mount Sharp, the Mars Science Laboratory Curiosity rover traversed the Bagnold Dune Field. We model sand modal mineralogy and grain size at four locations near the rover traverse, using orbital shortwave infrared single-scattering albedo spectra and a Markov chain Monte Carlo implementation of Hapke's radiative transfer theory to fully constrain uncertainties and permitted solutions. These predictions, evaluated against in situ measurements at one site from the Curiosity ...

High-speed combustion diagnostics in a rapid compression machine by broadband supercontinuum absorption spectroscopy.

Science.gov (United States)

Werblinski, Thomas; Fendt, Peter; Zigan, Lars; Will, Stefan

2017-05-20

The first results under fired internal combustion engine conditions based on a supercontinuum absorption spectrometer are presented and discussed. Temperature, pressure, and water mole fraction are inferred simultaneously from broadband H 2 O absorbance spectra ranging from 1340 nm to 1440 nm. The auto-ignition combustion process is monitored for two premixed n-heptane/air mixtures with 10 kHz in a rapid compression machine. Pressure and temperature levels during combustion exceed 65 bar and 1900 K, respectively. To allow for combustion measurements, the robustness of the spectrometer against beam steering has been improved compared to its previous version. Additionally, the detectable wavelength range has been extended further into the infrared region to allow for the acquisition of distinct high-temperature water transitions located in the P-branch above 1410 nm. Based on a theoretical study, line-of-sight (LOS) effects introduced by temperature stratification on the broadband fitting algorithm in the complete range from 1340 nm to 1440 nm are discussed. In this context, the recorded spectra during combustion were evaluated only within a narrower spectral region exhibiting almost no interference from low-temperature molecules (here, P-branch from 1410 nm to 1440 nm). It is shown that this strategy mitigates almost all of the LOS effects introduced by cold molecules and the evaluation of the spectrum in the entirely recorded wavelength range at engine combustion conditions.

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...

Management implications of broadband sound in modulating wild silver carp (Hypophthalmichthys molitrix) behavior

Science.gov (United States)

Vetter, Brooke J.; Calfee, Robin D.; Mensinger, Allen F.

2017-01-01

Invasive silver carp (Hypophthalmichthys molitrix) dominate large regions of the Mississippi River drainage, outcompete native species, and are notorious for their prolific and unusual jumping behavior. High densities of juvenile and adult (~25 kg) carp are known to jump up to 3 m above the water surface in response to moving watercraft. Broadband sound recorded from an outboard motor (100 hp at 32 km/hr) can modulate their behavior in captivity; however, the response of wild silver carp to broadband sound has yet to be determined. In this experiment, broadband sound (0.06–10 kHz) elicited jumping behavior from silver carp in the Spoon River near Havana, IL independent of boat movement, indicating acoustic stimulus alone is sufficient to induce jumping. Furthermore, the number of jumping fish decreased with subsequent sound exposures. Understanding silver carp jumping is not only important from a behavioral standpoint, it is also critical to determine effective techniques for controlling this harmful species, such as herding fish into a net for removal.

Temperature controlled infrared broadband cloaking with the bilayer coatings of semiconductor and superconductor

Energy Technology Data Exchange (ETDEWEB)

Wang, Xiaohua [College of Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); College of Physics and Electronics, Yancheng Teachers University, Yancheng 224051 (China); Liu, Youwen, E-mail: ywliu@nuaa.edu.cn [College of Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Feng, Yuncai [College of Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)

2015-06-15

Highlights: • We first propose that the cloak is composed of the bilayer of semiconductor and superconductor. • We realize the infrared broadband cloaking based on the scattering cancellation method. • The cloaking frequency can be tuned by external temperature. - Abstract: The infrared broadband tunable cloaking have been proposed and investigated with the bilayer coating materials of semiconductor (n-Ge) and high-temperature superconductor (YBa{sub 2}Cu{sub 3}O{sub 7}), whose cloaking frequency can be controlled by external temperature. The analytical solution is derived based on the scattering cancellation cloaking technique from the Mie scattering theory, and the full-wave numerical simulation is performed by the finite element method. The calculated and simulated results have demonstrated that this invisibility cloak may reduce the total scattering cross section of the composite structure of 90% over a broad frequency band of nearly 20 THz, and the infrared cloaking frequency can be tuned by the external temperature. It can provide a feasible way to design a broadband tunable cloak.

Monitoring Instrument Performance in Regional Broadband Seismic Network Using Ambient Seismic Noise

Science.gov (United States)

Ye, F.; Lyu, S.; Lin, J.

2017-12-01

In the past ten years, the number of seismic stations has increased significantly, and regional seismic networks with advanced technology have been gradually developed all over the world. The resulting broadband data help to improve the seismological research. It is important to monitor the performance of broadband instruments in a new network in a long period of time to ensure the accuracy of seismic records. Here, we propose a method that uses ambient noise data in the period range 5-25 s to monitor instrument performance and check data quality in situ. The method is based on an analysis of amplitude and phase index parameters calculated from pairwise cross-correlations of three stations, which provides multiple references for reliable error estimates. Index parameters calculated daily during a two-year observation period are evaluated to identify stations with instrument response errors in near real time. During data processing, initial instrument responses are used in place of available instrument responses to simulate instrument response errors, which are then used to verify our results. We also examine feasibility of the tailing noise using data from stations selected from USArray in different locations and analyze the possible instrumental errors resulting in time-shifts used to verify the method. Additionally, we show an application that effects of instrument response errors that experience pole-zeros variations on monitoring temporal variations in crustal properties appear statistically significant velocity perturbation larger than the standard deviation. The results indicate that monitoring seismic instrument performance helps eliminate data pollution before analysis begins.

Multimodal Broadband Vibrational Sum Frequency Generation (MM-BB-V-SFG) Spectrometer and Microscope.

Science.gov (United States)

Lee, Christopher M; Kafle, Kabindra; Huang, Shixin; Kim, Seong H

2016-01-14

A broadband sum frequency generation (BB-SFG) spectrometer with multimodal (MM) capabilities was constructed, which could be routinely reconfigured for tabletop experiments in reflection, transmission, and total internal reflection (TIR) geometries, as well as microscopic imaging. The system was constructed using a Ti:sapphire amplifier (800 nm, pulse width = 85 fs, repetition rate = 2 kHz), an optical parameter amplification (OPA) system for production of broadband IR pulses tunable between 1000 and 4000 cm(-1), and two Fabry-Pérot etalons arranged in series for production of narrowband 800 nm pulses. The key feature allowing the MM operation was the nearly collinear alignment of the visible (fixed, 800 nm) and infrared (tunable, 1000-4000 cm(-1)) pulses which were spatially separated. Physical insights discussed in this paper include the comparison of spectral bandwidth produced with 40 and 85 fs pump beams, the improvement of spectral resolution using etalons, the SFG probe volume in bulk analysis, the normalization of SFG signals, the stitching of multiple spectral segments, and the operation in different modes for air/liquid and adsorbate/solid interfaces, bulk samples, as well as spectral imaging combined with principle component analysis (PCA). The SFG spectral features obtained with the MM-BB-SFG system were compared with those obtained with picosecond-scanning-SFG system and high-resolution BB-SFG system (HR-BB-SFG) for dimethyl sulfoxide, α-pinene, and various samples containing cellulose (purified commercial products, Cladophora cell wall, cotton and flax fibers, and onion epidermis cell wall).

Customized broadband Sloan-filters for the JST/T250 and JAST/T80 telescopes: measurement summary

Science.gov (United States)

Brauneck, Ulf; Sprengard, Ruediger; Bourquin, Sebastien; Marín-Franch, Antonio

2018-01-01

The Centro de Estudios de Fisica del Cosmos de Aragon will conduct a photometric sky survey with two new telescopes recently set up on the Javalambre mountain in Spain: the JST/T250 is a 2.55-m telescope with a plate scale of 22.67 arc⁢sec/mm and a 3-deg-diameter field of view (FoV) and the auxiliary telescope JAST/T80 with a 82-cm primary mirror and an FoV of 2 deg diameter. A multiple CCD (9k-by-9k array size, 10-μm pixel size) mosaic camera is used in combination with filter trays or filter wheels, each containing a multitude of filters in dimensions of 101.7×96.5 mm or 106.8×106.8 mm. For this project, Schott manufactured 56 specially designed narrow band steep-edged bandpass interference filters and five broadband Sloan-filters which were completed only recently. We report here on the results of the broadband Sloan-filters with transmission bands of 324 to 400 nm (Sloan-u), 400 to 550 nm (Sloan-g), 550 to 700 nm (Sloan-r), 695 to 850 nm (Sloan-i), and 830 to 1200 nm (Sloan-z). The filters are composed of Schott filterglasses and clearglass substrates coated with interference filters and represent an improvement of broadband Sloan filters commonly used in astronomy. In spite of the absorptive elements, the filters show maximum possible transmissions achieved by magnetron sputtered filter coatings. In addition, the blocking of the filters is better than OD5 (transmission <10 to -5) in the range 250 to 1050 nm which was achieved by combining up to three substrates. A high image quality required a low transmitted wavefront error (<λ/8 locally, respectively <λ/2 globally). We report on the spectral and interferometric results measured on the filters.

Broadband and scalable mobile satellite communication system for future access networks

Science.gov (United States)

Ohata, Kohei; Kobayashi, Kiyoshi; Nakahira, Katsuya; Ueba, Masazumi

2005-07-01

Due to the recent market trends, NTT has begun research into next generation satellite communication systems, such as broadband and scalable mobile communication systems. One service application objective is to provide broadband Internet access for transportation systems, temporal broadband access networks and telemetries to remote areas. While these are niche markets the total amount of capacity should be significant. We set a 1-Gb/s total transmission capacity as our goal. Our key concern is the system cost, which means that the system should be unified system with diversified services and not tailored for each application. As satellites account for a large portion of the total system cost, we set the target satellite size as a small, one-ton class dry mass with a 2-kW class payload power. In addition to the payload power and weight, the mobile satellite's frequency band is extremely limited. Therefore, we need to develop innovative technologies that will reduce the weight and maximize spectrum and power efficiency. Another challenge is the need for the system to handle up to 50 dB and a wide data rate range of other applications. This paper describes the key communication system technologies; the frequency reuse strategy, multiplexing scheme, resource allocation scheme, and QoS management algorithm to ensure excellent spectrum efficiency and support a variety of services and quality requirements in the mobile environment.

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

Science.gov (United States)

2011-06-07

....5 megahertz from the channel edge, where (P) is the transmitter power measured in watts. 5.5... broadband applications. Another standard for wireless broadband technology is Long Term Evolution (LTE... refinements of WiMAX and LTE, which are known as WiMAX 2 (based on the 802.16m standard and LTE- Advanced...

Biobased Nanoparticles for Broadband UV Protection with Photostabilized UV Filters

NARCIS (Netherlands)

Hayden, D.R.|info:eu-repo/dai/nl/412640694; Imhof, A.|info:eu-repo/dai/nl/145641600; Velikov, K. P.|info:eu-repo/dai/nl/239483472

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

A broadband high-efficiency Doherty power amplifier using symmetrical devices

Science.gov (United States)

Cheng, Zhiqun; Zhang, Ming; Li, Jiangzhou; Liu, Guohua

2018-04-01

This paper proposes a method for broadband and high-efficiency amplification of Doherty power amplifier (DPA) using symmetric devices. In order to achieve the perfect load modulation, the carrier amplifier output circuit total power length is designed to odd multiple of 90°, and the peak amplifier output total power length is designed to even multiple of 180°. The proposed method is demonstrated by designing a broadband high-efficiency DPA using identical 10-W packaged GaN HEMT devices. Measurement results show that over 51% drain efficiency is achieved at 6-dB back-off power, over the frequency band of 1.9–2.4 GHz. Project supported by the National Natural Science Foundation of China (No. 60123456), the Zhejiang Provincial Natural Science Foundation of China (No. LZ16F010001), and the Zhejiang Provincial Public Technology Research Project (No. 2016C31070).

Broadband internet connection utilizing electric power cables, v. 16(61)

International Nuclear Information System (INIS)

Plastinovski, Jovche

2008-01-01

Considering the introduction of wide spread communication, once again, pay our attention to the oldest network in Macedonia(and world wide)- the electrical network. Being widespread, it can make the broadband communication available from any place that has an electrical connection. This includes the rural areas, which the commercial companies are not interested in. Since the early 80-ties the big power companies have realized the potential of the use electric network for communication. its beginning had faced with difficulties, since in order to send data via the noisy interferes with other units such as the radio and military equipment. But nowadays these obstacles are more or lass overcame. Some of the companies are using BPL (broadband power lines) communication for their daily operations, while in the same time this relatively new technology for data transfer over power lines is under heavy developing. (Author)

Broadband internet connection utilizing electric power cables, v. 16(62)

International Nuclear Information System (INIS)

Plastinovski, Jovche

2008-01-01

Considering the introduction of wide spread communication, once again, pay our attention to the oldest network in Macedonia(and world wide)- the electrical network. Being widespread, it can make the broadband communication available from any place that has an electrical connection. This includes the rural areas, which the commercial companies are not interested in. Since the early 80-ties the big power companies have realized the potential of the use electric network for communication. its beginning had faced with difficulties, since in order to send data via the noisy interferes with other units such as the radio and military equipment. But nowadays these obstacles are more or lass overcame. Some of the companies are using BPL (broadband power lines) communication for their daily operations, while in the same time this relatively new technology for data transfer over power lines is under heavy developing. (Author)

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.

Mirror-based broadband scanner with minimized aberration

Science.gov (United States)

Yu, Jiun-Yann; Tzeng, Yu-Yi; Huang, Chen-Han; Chui, Hsiang-Chen; Chu, Shi-Wei

2009-02-01

To obtain specific biochemical information in optical scanning microscopy, labeling technique is routinely required. Instead of the complex and invasive sample preparation procedures, incorporating spectral acquisition, which commonly requires a broadband light source, provides another mechanism to enhance molecular contrast. But most current optical scanning system is lens-based and thus the spectral bandwidth is limited to several hundred nanometers due to anti-reflection coating and chromatic aberration. The spectral range of interest in biological research covers ultraviolet to infrared. For example, the absorption peak of water falls around 3 μm, while most proteins exhibit absorption in the UV-visible regime. For imaging purpose, the transmission window of skin and cerebral tissues fall around 1300 and 1800 nm, respectively. Therefore, to extend the spectral bandwidth of an optical scanning system from visible to mid-infrared, we propose a system composed of metallic coated mirrors. A common issue in such a mirror-based system is aberrations induced by oblique incidence. We propose to compensate astigmatism by exchanging the sagittal and tangential planes of the converging spherical mirrors in the scanning system. With the aid of an optical design software, we build a diffraction-limited broadband scanning system with wavefront flatness better than λ/4 at focal plane. Combined with a mirror-based objective this microscopic system will exhibit full spectral capability and will be useful in microscopic imaging and therapeutic applications.

Broadband light trapping strategies for quantum-dot photovoltaic cells (>10%) and their issues with the measurement of photovoltaic characteristics.

Science.gov (United States)

Cho, Changsoon; Song, Jung Hoon; Kim, Changjo; Jeong, Sohee; Lee, Jung-Yong

2017-12-12

Bandgap tunability and broadband absorption make quantum-dot (QD) photovoltaic cells (PVs) a promising candidate for future solar energy conversion systems. Approaches to improving the electrical properties of the active layer increase efficiency in part. The present study focuses on optical room for enhancement in QD PVs over wide spectrum in the near-infrared (NIR) region. We find that ray-optical light trapping schemes rather than the nanophotonics approach may be the best solution for enhancing broadband QD PVs by suppressing the escape probability of internal photons without spectral dependency. Based on the theoretical study of diverse schemes for various bandgaps, we apply a V-groove structure and a V-groove textured compound parabolic trapper (VCPT) to PbS-based QD PVs along with the measurement issues for PVs with a light scattering layer. The efficiency of the best device is improved from 10.3% to 11.0% (certified to 10.8%) by a V-groove structure despite the possibility of underestimation caused by light scattering in small-area devices (aperture area: 0.0625 cm 2 ). By minimizing such underestimation, even greater enhancements of 13.6% and 15.6% in short circuit current are demonstrated for finger-type devices (0.167 cm 2 without aperture) and large-area devices (2.10 cm 2 with an aperture of 0.350 cm 2 ), respectively, using VCPT.

Thermodynamic Upper Bound on Broadband Light Coupling with Photonic Structures

KAUST Repository

Yu, Zongfu; Raman, Aaswath; Fan, Shanhui

2012-01-01

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

Estimation of shortwave direct aerosol radiative forcing at four locations on the Indo-Gangetic plains: Model results and ground measurement

Science.gov (United States)

Bibi, Humera; Alam, Khan; Bibi, Samina

2017-08-01

This study provides observational results of aerosol optical and radiative characteristics over four locations in IGP. Spectral variation of Aerosol Optical Depth (AOD), Single Scattering Albedo (SSA) and Asymmetry Parameter (AP) were analysed using AErosol RObotic NETwork (AERONET) data. The analysis revealed that coarse particles were dominant in summer and pre-monsoon, while fine particles were more pronounced in winter and post-monsoon. Furthermore, the spatio-temporal variations of Shortwave Direct Aerosol Radiative Forcing (SDARF) and Shortwave Direct Aerosol Radiative Forcing Efficiency (SDARFE) at the Top Of Atmosphere (TOA), SURface (SUR) and within ATMosphere (ATM) were calculated using SBDART model. The atmospheric Heating Rate (HR) associated with SDARFATM were also computed. It was observed that the monthly averaged SDARFTOA and SDARFSUR were found to be negative leading to positive SDARFATM during all the months over all sites. The increments in net atmospheric forcing lead to maximum HR in November-December and May. The seasonal analysis of SDARF revealed that SDARFTOA and SDARFSUR were negative during all seasons. The SW atmospheric absorption translates to highest atmospheric HR during summer over Karachi and during pre-monsoon over Lahore, Jaipur and Kanpur. Like SDARF, the monthly and seasonal variations of SDARFETOA and SDARFESUR were found to be negative, resulting in positive atmospheric forcing. Additionally, to compare the model estimated forcing against AERONET derived forcing, the regression analysis of AERONET-SBDART forcing were carried out. It was observed that SDARF at SUR and TOA showed relatively higher correlation over Lahore, moderate over Jaipur and Kanpur and lower over Karachi. Finally, the analysis of National Oceanic and Atmospheric Administration Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model revealed that air masses were arriving from multiple source locations.

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 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...

Improvement of intelligibility of ideal binary-masked noisy speech by adding background noise.

Science.gov (United States)

Cao, Shuyang; Li, Liang; Wu, Xihong

2011-04-01

When a target-speech/masker mixture is processed with the signal-separation technique, ideal binary mask (IBM), intelligibility of target speech is remarkably improved in both normal-hearing listeners and hearing-impaired listeners. Intelligibility of speech can also be improved by filling in speech gaps with un-modulated broadband noise. This study investigated whether intelligibility of target speech in the IBM-treated target-speech/masker mixture can be further improved by adding a broadband-noise background. The results of this study show that following the IBM manipulation, which remarkably released target speech from speech-spectrum noise, foreign-speech, or native-speech masking (experiment 1), adding a broadband-noise background with the signal-to-noise ratio no less than 4 dB significantly improved intelligibility of target speech when the masker was either noise (experiment 2) or speech (experiment 3). The results suggest that since adding the noise background shallows the areas of silence in the time-frequency domain of the IBM-treated target-speech/masker mixture, the abruption of transient changes in the mixture is smoothed and the perceived continuity of target-speech components becomes enhanced, leading to improved target-speech intelligibility. The findings are useful for advancing computational auditory scene analysis, hearing-aid/cochlear-implant designs, and understanding of speech perception under "cocktail-party" conditions.

The long-term Global LAnd Surface Satellite (GLASS) product suite and applications

Science.gov (United States)

Liang, S.

2015-12-01

Our Earth's environment is experiencing rapid changes due to natural variability and human activities. To monitor, understand and predict environment changes to meet the economic, social and environmental needs, use of long-term high-quality satellite data products is critical. The Global LAnd Surface Satellite (GLASS) product suite, generated at Beijing Normal University, currently includes 12 products, including leaf area index (LAI), broadband shortwave albedo, broadband longwave emissivity, downwelling shortwave radiation and photosynthetically active radiation, land surface skin temperature, longwave net radiation, daytime all-wave net radiation, fraction of absorbed photosynetically active radiation absorbed by green vegetation (FAPAR), fraction of green vegetation coverage, gross primary productivity (GPP), and evapotranspiration (ET). Most products span from 1981-2014. The algorithms for producing these products have been published in the top remote sensing related journals and books. More and more applications have being reported in the scientific literature. The GLASS products are freely available at the Center for Global Change Data Processing and Analysis of Beijing Normal University (http://www.bnu-datacenter.com/), and the University of Maryland Global Land Cover Facility (http://glcf.umd.edu). After briefly introducing the basic characteristics of GLASS products, we will present some applications on the long-term environmental changes detected from GLASS products at both global and local scales. Detailed analysis of regional hotspots, such as Greenland, Tibetan plateau, and northern China, will be emphasized, where environmental changes have been mainly associated with climate warming, drought, land-atmosphere interactions, and human activities.

Are classroom internet use and academic performance higher after government broadband subsidies to primary schools?

OpenAIRE

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

2013-01-01

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...

Speckle noise reduction on a laser projection display via a broadband green light source.

Science.gov (United States)

Yu, Nan Ei; Choi, Ju Won; Kang, Heejong; Ko, Do-Kyeong; Fu, Shih-Hao; Liou, Jiun-Wei; Kung, Andy H; Choi, Hee Joo; Kim, Byoung Joo; Cha, Myoungsik; Peng, Lung-Han

2014-02-10

A broadband green light source was demonstrated using a tandem-poled lithium niobate (TPLN) crystal. The measured wavelength and temperature bandwidth were 6.5 nm and 100 °C, respectively, spectral bandwidth was 36 times broader than the periodically poled case. Although the conversion efficiency was smaller than in the periodic case, the TPLN device had a good figure of merit owing to the extremely large bandwidth for wavelength and temperature. The developed broadband green light source exhibited speckle noise approximately one-seventh of that in the conventional approach for a laser projection display.

Highly Reflecting, Broadband Deformable Membrane Mirror for Wavefront Control Applications, Phase I

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...

Freely tunable broadband polarization rotator for terahertz waves.

Science.gov (United States)

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

2015-02-18

A freely tunable polarization rotator for broadband terahertz waves is demonstrated using a three-rotating-layer metallic grating structure, which can conveniently rotate the polarization of a linearly polarized terahertz wave to any desired direction with nearly perfect conversion efficiency. This low-cost, high-efficiency, and freely tunable device has potential applications as material analysis, wireless communication, and THz imaging. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Broad-Band Spectral Indices Variability of BL Lacertae by Wavelet ...

Indian Academy of Sciences (India)

by Wavelet Method. Hao-Jing Zhang1,2,∗, Jing-Ming Bai1, Yu-Ying Bao3 & Xiong Zhang2. 1Yunnan Astronomical Observatory, National Astronomical Observatory, ... 3Department of Physics, Yuxi Teachers' College, Yuxi, Yunnan 653100, China. ∗ ... broad-band spectral indices—periodic variation—methods: numerical:.

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

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...

Broadband Two-Photon Absorption Characteristics of Highly Photostable Fluorenyl-Dicyanoethylenylated [60]Fullerene Dyads

Directory of Open Access Journals (Sweden)

Seaho Jeon

2016-05-01

Full Text Available We synthesized four C60-(light-harvesting antenna dyads C60 (>CPAF-Cn (n = 4, 9, 12, or 18 1-Cn for the investigation of their broadband nonlinear absorption effect. Since we have previously demonstrated their high function as two-photon absorption (2PA materials at 1000 nm, a different 2PA wavelength of 780 nm was applied in the study. The combined data taken at two different wavelength ranges substantiated the broadband characteristics of 1-Cn. We proposed that the observed broadband absorptions may be attributed by a partial π-conjugation between the C60 > cage and CPAF-Cn moieties, via endinitrile tautomeric resonance, giving a resonance state with enhanced molecular conjugation. This transient state could increase its 2PA and excited-state absorption at 800 nm. In addition, a trend of concentration-dependent 2PA cross-section (σ2 and excited-state absorption magnitude was detected showing a higher σ value at a lower concentration that was correlated to increasing molecular separation with less aggregation for dyads C60(>CPAF-C18 and C60(>CPAF-C9, as better 2PA and excited-state absorbers.