75 FR 35989 - Facilitating the Provision of Fixed and Mobile Broadband Access, Educational and Other Advanced...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-24

...] Facilitating the Provision of Fixed and Mobile Broadband Access, Educational and Other Advanced Services in the...), clarifying the requirements necessary for Broadband Radio Service (BRS) and Educational Broadband Service (EBS) licensees to demonstrate substantial service and ensure that BRS licensees of new initial...

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

Code of Federal Regulations, 2013 CFR

2013-10-01

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

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

Code of Federal Regulations, 2012 CFR

2012-10-01

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

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

Code of Federal Regulations, 2014 CFR

2014-10-01

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

76 FR 33686 - Proposed Extension of Part 4 of the Commission's Rules Regarding Outage Reporting to...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-09

... broadband ISPs, a term which includes broadband Internet access service providers and broadband backbone... Internet consumers and businesses that purchase Internet access through less traditional access arrangements (e.g., prepaid Internet access cards). 23. Some broadband ISPs provide Internet access directly...

Chaos-assisted broadband momentum transformation in optical microresonators

NASA Astrophysics Data System (ADS)

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.

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

ERIC Educational Resources Information Center

Menon, Siddhartha Shankar

2010-01-01

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

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

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-18

... Docket 07-100; FCC 11-6] Implementing a Nationwide, Broadband, Interoperable Public Safety Network in the... interoperable public safety broadband network. The establishment of a common air interface for 700 MHz public safety broadband networks will create a foundation for interoperability and provide a clear path for the...

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

ERIC Educational Resources Information Center

Pastore, Erica; Henderson, Everett

2009-01-01

America needs greater access to broadband Internet to spur economic growth, innovation, and job creation. To date, gains in household broadband take-up are not evenly distributed across all demographic groups or geographic areas. While from 2001 to 2007, the percentage of households in the United States with access to broadband Internet services…

A Comprehensive Review of Helicopter Noise Literature

DTIC Science & Technology

1975-06-01

Broadband Noise .... ........................ .0.0.0 13 Impulsive Noise .......... ........... ............... ... *. i Introduction... broadband noise is probably the turbulence in the flow seen by the rotor blades. Trhe prediction of rotor broadband noise based on rotor geometry amd...acoustic processes, but rely on generalization of existing test data. The recent impetus to study broadband noise is the result of reducing

On the suitability of broadband attenuation measurement for characterizing contrast microbubbles.

PubMed

Chatterjee, Dhiman; Sarkar, Kausik; Jain, Pankaj; Schreppler, Nathan E

2005-06-01

Broadband attenuation measurement has been widely used for characterizing ultrasound contrast agents. Chen et al. (2002) recently suggested that broadband attenuation data depend on the center frequency of the broadband excitation pulse and, therefore, that they are not a reliable measure of the bubble behavior. We investigated the suitability of measurement of broadband attenuation as a characterizing tool using the contrast agent Definity as a test case. Analyzing the attenuation data obtained with three broadband unfocused transducers with different center frequencies (2.25, 3.5 and 5 MHz), we found that attenuation is independent of the transducer used and matches in the overlap regions of any two transducers. Attenuation does not depend on excitation pressure amplitude as long as the excitation amplitude remains below a critical value ( approximately 0.26 MPa), indicating that the measurement of broadband attenuation below critical excitation can, indeed, be used for characterization. Furthermore, the linear relationship of attenuation with concentrations of Definity is also investigated.

Chaos-assisted broadband momentum transformation in optical microresonators.

PubMed

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.

Customer Churn Prediction for Broadband Internet Services

NASA Astrophysics Data System (ADS)

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

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

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

PubMed

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 Liner Optimization for the Source Diagnostic Test Fan

NASA Technical Reports Server (NTRS)

Nark, Douglas M.; Jones, Michael G.

2012-01-01

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

Making structured metals transparent for ultrabroadband electromagnetic waves and acoustic waves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fan, Ren-Hao; Peng, Ru-Wen, E-mail: rwpeng@nju.edu.cn; Huang, Xian-Rong

2015-07-15

In this review, we present our recent work on making structured metals transparent for broadband electromagnetic waves and acoustic waves via excitation of surface waves. First, we theoretically show that one-dimensional metallic gratings can become transparent and completely antireflective for extremely broadband electromagnetic waves by relying on surface plasmons or spoof surface plasmons. Second, we experimentally demonstrate that metallic gratings with narrow slits are highly transparent for broadband terahertz waves at oblique incidence and high transmission efficiency is insensitive to the metal thickness. Further, we significantly develop oblique metal gratings transparent for broadband electromagnetic waves (including optical waves and terahertzmore » ones) under normal incidence. In the third, we find the principles of broadband transparency for structured metals can be extended from one-dimensional metallic gratings to two-dimensional cases. Moreover, similar phenomena are found in sonic artificially metallic structures, which present the transparency for broadband acoustic waves. These investigations provide guidelines to develop many novel materials and devices, such as transparent conducting panels, antireflective solar cells, and other broadband metamaterials and stealth technologies. - Highlights: • Making structured metals transparent for ultrabroadband electromagnetic waves. • Non-resonant excitation of surface plasmons or spoof surface plasmons. • Sonic artificially metallic structures transparent for broadband acoustic waves.« less

75 FR 6627 - Broadband Technology Opportunities Program

Federal Register 2010, 2011, 2012, 2013, 2014

2010-02-10

... DEPARTMENT OF COMMERCE National Telecommunications and Information Administration [Docket No. 0907141137-0079-07] RIN 0660-ZA28 Broadband Technology Opportunities Program AGENCY: National... policy and application procedures for the Broadband Technology Opportunities Program (BTOP) established...

Making structured metals transparent for ultrabroadband electromagnetic waves and acoustic waves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fan, Ren-Hao; Peng, Ru-Wen; Huang, Xian-Rong

2015-07-01

In this review, we present our recent work on making structured metals transparent for broadband electromagnetic waves and acoustic waves via excitation of surface waves. First, we theoretically show that one-dimensional metallic gratings can become transparent and completely antireflective for extremely broadband electromagnetic waves by relying on surface plasmons or spoof surface plasmons. Second, we experimentally demonstrate that metallic gratings with narrow slits are highly transparent for broadband terahertz waves at oblique incidence and high transmission efficiency is insensitive to the metal thickness. Further, we significantly develop oblique metal gratings transparent for broadband electromagnetic waves (including optical waves and terahertzmore » ones) under normal incidence. In the third, we find the principles of broadband transparency for structured metals can be extended from one-dimensional metallic gratings to two-dimensional cases. Moreover, similar phenomena are found in sonic artificially metallic structures, which present the transparency for broadband acoustic waves. These investigations provide guidelines to develop many novel materials and devices, such as transparent conducting panels, antireflective solar cells, and other broadband metamaterials and stealth technologies.« less

75 FR 10464 - Broadband Technology Opportunities Program

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-08

... DEPARTMENT OF COMMERCE National Telecommunications and Information Administration [Docket Number 0907141137-0119-08] RIN 0660-ZA28 Broadband Technology Opportunities Program AGENCY: National... Infrastructure (CCI) projects under the Broadband Technology Opportunities Program (BTOP) is extended until 5:00...

75 FR 14131 - Broadband Technology Opportunities Program

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-24

... DEPARTMENT OF COMMERCE National Telecommunications and Information Administration [Docket Number: 0907141137-0154-09] RIN 0660-ZA28 Broadband Technology Opportunities Program AGENCY: National... under the Broadband Technology Opportunities Program (BTOP) is extended until 10 p.m. Eastern Daylight...

A mixed-modem approach to data isolation on a broadband local area network

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crutcher, R.I.; Ewing, P.D.

1988-01-01

Data isolation is required to broadband networks to prevent unauthorized access to the sensitive data of other users. Isolation can be obtained by using equipment from more than one manufacturer to introduce incompatibility between nonassociated users. This paper develops the basis for isolation and postulates that four layers of isolation will exist when the proper equipment is chosen. An experimental broadband local area network (LAN) was constructed to verify isolation. This independent network allowed variations in operating conditions without causing interference in normal broadband operations. The measured results indicate that a broadband LAN can transmit data of varying sensitivity levelsmore » without compromising data security. When combined with certain administrative restrictions, the mixed-modem technique provides a cost-effective method of sharing a broadband network while maintaining isolation of data having different sensitivities. 5 refs., 2 figs.« less

A mixed-modem solution for sensitive data segregation on a broadband network

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crutcher, R.I.; Ewing, P.D.

1988-01-01

Data isolation is required in broadband networks to prevent unauthorized access to the sensitive data of other users. Isolation can be obtained by using equipment from different manufacturers to introduce incompatibility between nonassociated users. This paper develops the basis for isolation and postulates that four layers of ioslation will exist when the proper equipment is chosen. An experimental broadband local area network (LAN) was constructed to verify isolation. This independent test system allowed variations to network operating conditions without causing interference to normal broadband operations. The measured results indicate that a broadband LAN can transmit data of varying sensitivity levelsmore » without compromising data security. When combined with the proper administrative restrictions, the mixed-modem technique provides a cost-effective method of sharing a broadband network while maintaining isolation of data having different sensitivities. 6 refs., 3 figs.« less

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

NASA Technical Reports Server (NTRS)

Chou, Shau-Tak Rudy

1990-01-01

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

Characteristics of a Broadband Dye Laser Using Pyrromethene and Rhodamine Dyes

NASA Technical Reports Server (NTRS)

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.

Evaluation of introduction scenarios for a broadband access network

NASA Astrophysics Data System (ADS)

Bocker, Geert-Jan; Cuthbert, Laurie; Gobbi, Roberta; Inch, Robert; Sara, Lini

1995-02-01

The provision of broadband services at a reasonable cost to residential and small business customers is one of the major challenges facing operators. The introduction of cost-effective systems considering the existing infrastructure is an important study. Within the RACE project 2024 Broadband Access Facilities, the economic and evolution aspects of different introduction scenarios of a broadband access system suitable for providing these services are investigated. This paper presents the final results of this study.

Broadband optical equalizer using fault tolerant digital micromirrors.

PubMed

Riza, Nabeel; Mughal, M Junaid

2003-06-30

For the first time, the design and demonstration of a near continuous spectral processing mode broadband equalizer is described using the earlier proposed macro-pixel spatial approach for multiwavelength fiber-optic attenuation in combination with a high spectral resolution broadband transmissive volume Bragg grating. The demonstrated design features low loss and low polarization dependent loss with broadband operation. Such an analog mode spectral processor can impact optical applications ranging from test and instrumentation to dynamic alloptical networks.

Metropolitan area networks: a corner stone in the broadband era

NASA Astrophysics Data System (ADS)

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

47 CFR 27.1203 - EBS programming requirements.

Code of Federal Regulations, 2010 CFR

2010-10-01

... MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27... Broadband Service stations are intended primarily through video, data, or voice transmissions to further the... endeavors; (2) Transmission of material directly related to the administrative activities of the licensee...

Broadband Pillbox Antennas.

DTIC Science & Technology

1984-09-21

Identify by block number) - FIELD GROUP SUB-GROUP Double layer pillbox antennas Triple layer pillbox antenna The possibility of designing very broadband... Design .................... 1 Broadband Feed De gn ........................................... 2 Ex mental Simulation of Double Layer Pillbox...5 REFERENCES ................................................... 6 APPENDIX - COAXIAL TO WAVEGUIDE JUNCTION DESIGN

Broadband radiometric LED measurements

NASA Astrophysics Data System (ADS)

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.

BREAD: a European coordination action for broadband for all

NASA Astrophysics Data System (ADS)

Van Daele, P.

2006-10-01

The BREAD - co-ordination action, funded by the European Commission through the Framework 6 Programme (FP6) aims at developing a multi-disciplinary approach for the realization of the 'Broadband for All' concept within Europe, bringing together societal, economic, regulatory and technological disciplines and presenting information from regional "success stories" of actual deployment. The EU objective of achieving "Broadband for All" will not be reached by solely a 'technology push' strategy but will need this multi-disciplinary approach and sharing of views and knowledge to develop new strategies and good practice recommendations in the area of 'Broadband for All'. As a co-ordination action the project wants to unite all players active in the field of the end-to-end broadband provisioning for all. It performs a multi-technological analysis of the current and evolving situation, starting from the roadmap information generated by different projects and IST instruments which focus on specific technological domains. The BREAD consortium simultaneously studies the techno-economic, societal and regulatory aspects of this "Broadband for All" concept. It tries to identify the impact of the EU regulatory framework on the successful implementation of new broadband communication services.

47 CFR 27.1200 - Change to BRS and EBS.

Code of Federal Regulations, 2014 CFR

2014-10-01

... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27.1200 Change to BRS and EBS... Multichannel Multipoint Distribution Service (MMDS) shall be reassigned to the Broadband Radio Service (BRS...

47 CFR 27.1200 - Change to BRS and EBS.

Code of Federal Regulations, 2012 CFR

2012-10-01

... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27.1200 Change to BRS and EBS... Multichannel Multipoint Distribution Service (MMDS) shall be reassigned to the Broadband Radio Service (BRS...

47 CFR 27.1200 - Change to BRS and EBS.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27.1200 Change to BRS and EBS... Multichannel Multipoint Distribution Service (MMDS) shall be reassigned to the Broadband Radio Service (BRS...

47 CFR 27.1200 - Change to BRS and EBS.

Code of Federal Regulations, 2013 CFR

2013-10-01

... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27.1200 Change to BRS and EBS... Multichannel Multipoint Distribution Service (MMDS) shall be reassigned to the Broadband Radio Service (BRS...

47 CFR 27.1200 - Change to BRS and EBS.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27.1200 Change to BRS and EBS... Multichannel Multipoint Distribution Service (MMDS) shall be reassigned to the Broadband Radio Service (BRS...

Dielectric Loaded Broadband Gyro-TWT System

DTIC Science & Technology

1993-12-31

A•wov•] f~ •ubic re] ease ;a AD-A277 889 -4 LLV t Final Report 01 Jan 92 - 31 Dec 93 DIELECTRIC LOADED BROADBAND GYRO- TWT SYSTEM Professor N. C...Loaded Broadband Gyro- TWT System" CONTRACT / GRANT NO.: F49620-92-J-O 175 CONTRACT / GRANT VALUE: $89,816 Acce’son For CONTRACT / GRANT PERIOD OF... Broadband Dielectric-Loaded Gyro- TWT Amplifier," submitted for publication to Physics Review Letters, October, 1993. A. Gover, F.V. Hartemann, G.P. Le

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

DOE PAGES

Graves, Robert; Pitarka, Arben

2014-12-17

This brief article describes refinements to the Graves and Pitarka (2010) broadband ground-motion simulation methodology (GP2010 hereafter) that have been implemented in version 14.3 of the Southern California Earthquake Center (SCEC) Broadband Platform (BBP). The updated version of our method on the current SCEC BBP is referred to as GP14.3. Here, our simulation technique is a hybrid approach that combines low- and high-frequency motions computed with different methods into a single broadband response.

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

NASA Astrophysics Data System (ADS)

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

2013-12-01

The Southern California Earthquake Center (SCEC) Broadband Platform is a collaborative software development project involving SCEC researchers, graduate students, and the SCEC Community Modeling Environment. The SCEC Broadband Platform is open-source scientific software that can generate broadband (0-100Hz) ground motions for earthquakes, integrating complex scientific modules that implement rupture generation, low and high-frequency seismogram synthesis, non-linear site effects calculation, and visualization into a software system that supports easy on-demand computation of seismograms. The Broadband Platform operates in two primary modes: validation simulations and scenario simulations. In validation mode, the Broadband Platform runs earthquake rupture and wave propagation modeling software to calculate seismograms of a historical earthquake for which observed strong ground motion data is available. Also in validation mode, the Broadband Platform calculates a number of goodness of fit measurements that quantify how well the model-based broadband seismograms match the observed seismograms for a certain event. Based on these results, the Platform can be used to tune and validate different numerical modeling techniques. During the past year, we have modified the software to enable the addition of a large number of historical events, and we are now adding validation simulation inputs and observational data for 23 historical events covering the Eastern and Western United States, Japan, Taiwan, Turkey, and Italy. In scenario mode, the Broadband Platform can run simulations for hypothetical (scenario) earthquakes. In this mode, users input an earthquake description, a list of station names and locations, and a 1D velocity model for their region of interest, and the Broadband Platform software then calculates ground motions for the specified stations. By establishing an interface between scientific modules with a common set of input and output files, the Broadband Platform facilitates the addition of new scientific methods, which are written by earth scientists in a number of languages such as C, C++, Fortran, and Python. The Broadband Platform's modular design also supports the reuse of existing software modules as building blocks to create new scientific methods. Additionally, the Platform implements a wrapper around each scientific module, converting input and output files to and from the specific formats required (or produced) by individual scientific codes. Working in close collaboration with scientists and research engineers, the SCEC software development group continues to add new capabilities to the Broadband Platform and to release new versions as open-source scientific software distributions that can be compiled and run on many Linux computer systems. Our latest release includes the addition of 3 new simulation methods and several new data products, such as map and distance-based goodness of fit plots. Finally, as the number and complexity of scenarios simulated using the Broadband Platform increase, we have added batching utilities to substantially improve support for running large-scale simulations on computing clusters.

Broadband athermal waveguides and devices for datacom and telecom applications

NASA Astrophysics Data System (ADS)

He, Liuqing; Guo, Yuhao; Han, Zhaohong; Wada, Kazumi; Kimerling, Lionel C.; Michel, Jurgen; Agarwal, Anuradha M.; Li, Guifang; Zhang, Lin

2018-02-01

The high temperature sensitivity of silicon material limits the applications of silicon-based micro-ring resonators in integrated photonics. To realize a low but broadband temperature-dependence-wavelength-shift (TDWS) micro-ring resonator, designing a broadband athermal waveguide becomes a significant task. In this work, we propose a broadband athermal waveguide which shows a low effective thermos-optical coefficient (TOC) of +/-1×10-6/K at 1400 nm to 1700 nm. The proposed waveguide shows low-loss performance of 0.01 dB/cm and stable broadband-athermal ability when it's applied in micro-ring resonators, and the optical loss of micro-ring resonator with a radius of 100 μm using this waveguide is 0.02 dB/cm.

Direct and quantitative broadband absorptance spectroscopy with multilayer cantilever probes

DOEpatents

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.

7 CFR 1738.11 - Availability of broadband service.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 11 2010-01-01 2010-01-01 false Availability of broadband service. 1738.11 Section 1738.11 Agriculture Regulations of the Department of Agriculture (Continued) RURAL UTILITIES SERVICE, DEPARTMENT OF AGRICULTURE RURAL BROADBAND ACCESS LOANS AND LOAN GUARANTEES Loan Purposes and Basic Policies...

Funding Public Computing Centers: Balancing Broadband Availability and Expected Demand

ERIC Educational Resources Information Center

Jayakar, Krishna; Park, Eun-A

2012-01-01

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

Fan Noise Source Diagnostic Test Computation of Rotor Wake Turbulence Noise

NASA Technical Reports Server (NTRS)

Nallasamy, M.; Envia, E.; Thorp, S. A.; Shabbir, A.

2002-01-01

An important source mechanism of fan broadband noise is the interaction of rotor wake turbulence with the fan outlet guide vanes. A broadband noise model that utilizes computed rotor flow turbulence from a RANS code is used to predict fan broadband noise spectra. The noise model is employed to examine the broadband noise characteristics of the 22-inch Source Diagnostic Test fan rig for which broadband noise data were obtained in wind tunnel tests at the NASA Glenn Research Center. A 9-case matrix of three outlet guide vane configurations at three representative fan tip speeds are considered. For all cases inlet and exhaust acoustic power spectra are computed and compared with the measured spectra where possible. In general, the acoustic power levels and shape of the predicted spectra are in good agreement with the measured data. The predicted spectra show the experimentally observed trends with fan tip speed, vane count, and vane sweep. The results also demonstrate the validity of using CFD-based turbulence information for fan broadband noise calculations.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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; identificationmore » 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.« less

75 FR 28781 - Proposed Information Collection; Comment Request; Broadband Subscription and Usage Supplement to...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-24

... Information Collection; Comment Request; Broadband Subscription and Usage Supplement to the Census Bureau's Current Population Survey AGENCY: National Telecommunications and Information Administration. ACTION... Population Survey (CPS) in order to gather reliable data on broadband (also known as high-speed Internet) use...

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

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-15

... Information Collection; Comment Request; Broadband Technology Opportunities Program Post-Award Quarterly and... (Recovery Act) establishes and provides $4.7 billion for the Broadband Technology Opportunities Program... million will be made available for competitive grants to expand public computer center capacity; at least...

77 FR 36903 - Accelerating Broadband Infrastructure Deployment

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-20

... coordination with the Chief Performance Officer (CPO). (b) The Working Group shall be composed of: (i) a... broadband infrastructure. Sec. 2. Broadband Deployment on Federal Property Working Group. (a) In order to... Property Working Group (Working Group), to be co-chaired by representatives designated by the Administrator...

47 CFR 1.9047 - Special provisions relating to leases of educational broadband service spectrum.

Code of Federal Regulations, 2014 CFR

2014-10-01

... educational broadband service spectrum. 1.9047 Section 1.9047 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL PRACTICE AND PROCEDURE Grants by Random Selection Spectrum Leasing General Policies and Procedures § 1.9047 Special provisions relating to leases of educational broadband service spectrum...

47 CFR 1.9047 - Special provisions relating to leases of educational broadband service spectrum.

Code of Federal Regulations, 2010 CFR

2010-10-01

... educational broadband service spectrum. 1.9047 Section 1.9047 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL PRACTICE AND PROCEDURE Spectrum Leasing General Policies and Procedures § 1.9047 Special provisions relating to leases of educational broadband service spectrum. Licensees in the Educational...

47 CFR 1.9047 - Special provisions relating to leases of educational broadband service spectrum.

Code of Federal Regulations, 2011 CFR

2011-10-01

... educational broadband service spectrum. 1.9047 Section 1.9047 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL PRACTICE AND PROCEDURE Spectrum Leasing General Policies and Procedures § 1.9047 Special provisions relating to leases of educational broadband service spectrum. Licensees in the Educational...

47 CFR 1.9047 - Special provisions relating to leases of educational broadband service spectrum.

Code of Federal Regulations, 2013 CFR

2013-10-01

... educational broadband service spectrum. 1.9047 Section 1.9047 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL PRACTICE AND PROCEDURE Grants by Random Selection Spectrum Leasing General Policies and Procedures § 1.9047 Special provisions relating to leases of educational broadband service spectrum...

47 CFR 1.9047 - Special provisions relating to leases of educational broadband service spectrum.

Code of Federal Regulations, 2012 CFR

2012-10-01

... educational broadband service spectrum. 1.9047 Section 1.9047 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL PRACTICE AND PROCEDURE Grants by Random Selection Spectrum Leasing General Policies and Procedures § 1.9047 Special provisions relating to leases of educational broadband service spectrum...

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

Federal Register 2010, 2011, 2012, 2013, 2014

2011-04-28

... FEDERAL COMMUNICATIONS COMMISSION [PS Docket Nos. 11-60 and 10-92; ET Docket No. 06-119] Reliability and Continuity of Communications Networks, Including Broadband Technologies; Effects on Broadband Communications Networks of Damage or Failure of Network Equipment or Severe Overload; Independent Panel Reviewing...

7 CFR 1738.19 - Facilities financed.

Code of Federal Regulations, 2010 CFR

2010-01-01

... broadband loans to finance broadband facilities leased under the terms of a capital lease as defined in... under the terms of an operating lease as defined in generally accepted accounting principles. (c) RUS... applicant. (e) RUS will not make a broadband loan to finance the following items: (1) Customer terminal...

Implementation of a Broadband Cable System on a University Campus.

ERIC Educational Resources Information Center

Rhoadarmer, Michael

1995-01-01

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

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

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-11

...; DA 10-988] Comment Sought on Measurement of Mobile Broadband Network Performance and Coverage AGENCY... broadband services. The Bureau seeks comment on whether and how to pursue a measurement program for mobile... and coverage, and continue to work with measurement companies, application designers, device...

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

Code of Federal Regulations, 2011 CFR

2011-10-01

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

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

Code of Federal Regulations, 2010 CFR

2010-10-01

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

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

PubMed

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.

Municipal Broadband in Wilson, North Carolina: A Study

ERIC Educational Resources Information Center

O'Boyle, Timothy

2012-01-01

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

Broadband Helps Bridge the Achievement Gap

ERIC Educational Resources Information Center

Simmons, Jamal

2013-01-01

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

76 FR 7207 - Notice of Public Information Collection Being Reviewed by the Federal Communications Commission...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-02-09

... Docket No. 07-52, FCC 10-201, require all providers of broadband Internet access service to publicly... of their broadband Internet access services sufficient for consumers to make informed choices... Network Management Practices, Preserving the Open Internet and Broadband Industry Practices, Report and...

75 FR 48235 - Rural Health Care Universal Service Support Mechanism

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-09

... references to recognized broadband mapping studies, such as NTIA's national broadband map, State or local... network area. In addition to referencing such NTIA or State broadband mapping studies, the applicant would... network design studies (but not in excess of the cap identified below); (2) engineering, materials and...

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

NASA Astrophysics Data System (ADS)

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 infrared beam splitter for spaceborne interferometric infrared sounder.

PubMed

Yu, Tianyan; Liu, Dingquan; Qin, Yang

2014-10-01

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

Meta-atom cluster acoustic metamaterial with broadband negative effective mass density

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Huaijun; Zhai, Shilong; Ding, Changlin

2014-02-07

We design a resonant meta-atom cluster, via which a two-dimensional (2D) acoustic metamaterial (AM) with broadband negative effective mass density from 1560 Hz to 5580 Hz is fabricated. Experimental results confirm that there is only weak interaction among the meta-atoms in the cluster. And then the meta-atoms in the cluster independently resonate, resulting in the cluster becoming equivalent to a broadband resonance unit. Extracted effective refractive indices from reflection and transmission measurements of the 2D AM appear to be negative from 1500 Hz to 5480 Hz. The broadband negative refraction has also been demonstrated by our further experiments. We expectmore » that this meta-atom cluster AM will significantly contribute to the design of broadband negative effective mass density AM.« less

Characteristics of a broadband dye laser using Pyrromethene and Rhodamine dyes.

PubMed

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

2011-02-20

A broadband dye laser pumped by a frequency-doubled Nd:YAG laser with a full width at half-maximum from 592 to 610 nm was created for the use in a dual-pump broadband coherent anti-Stokes Raman spectroscopy (CARS) system called width increased dual-pump enhanced CARS (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 was 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 and Pyrromethene dyes 597 and 650, as well as mixtures of these dyes.

Broadband Radiometric LED Measurements

PubMed Central

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

2017-01-01

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

Broadband Radiometric LED Measurements.

PubMed

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

2016-01-01

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

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

NASA Astrophysics Data System (ADS)

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

2014-12-01

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

77 FR 30423 - Innovation in the Broadcast Television Bands: Allocations, Channel Sharing and Improvements to...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-23

... uses. This action serves to further address the nation's growing demand for wireless broadband services... keeps pace with the global wireless revolution. At the same time, the approach helps preserve broadcast... National Broadband Plan to repurpose spectrum from the U/V bands for new wireless broadband uses through...

Silicon graphene waveguide tunable broadband microwave photonics phase shifter.

PubMed

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.

First Time Facilitator's Experience: Designing and Facilitating an Action Learning Programme in China

ERIC Educational Resources Information Center

Wang, Jinshuai; Bloodworth, Mike

2016-01-01

This paper describes an action learning programme with China Unicom Broadband Limited (CUBO) to support its vision of transforming to become a world-leading broadband communications and information service provider. 64 Department directors and supervisors were invited to take part in the "China Unicom Broadband Online Phoenix Action Learning…

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

Federal Register 2010, 2011, 2012, 2013, 2014

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...

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

ERIC Educational Resources Information Center

Executive Office of the President, 2009

2009-01-01

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

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

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-28

... DEPARTMENT OF AGRICULTURE Rural Utilities Service Rural Broadband Access Loans and Loan Guarantees... of $325,663,157 in loan funds for the Rural Broadband Access Loans and Loan Guarantees Program for... identifying a definite funding amount. The maximum amount of a loan under this authority will be $75 million...

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

USGS Publications Warehouse

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.

The Prediction of Scattered Broadband Shock-Associated Noise

NASA Technical Reports Server (NTRS)

Miller, Steven A. E.

2015-01-01

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

Broadband and efficient plasmonic control in the near-infrared and visible via strong interference of surface plasmon polaritons.

PubMed

Gan, C H; Nash, G R

2013-11-01

Broadband and tunable control of surface plasmon polaritons in the near-infrared and visible spectrum is demonstrated theoretically and numerically with a pair of phased nanoslits. We establish, with simulations supported by a coupled wave model, that by dividing the incident power equally between two input channels, the maximum plasmon intensity deliverable to either side of the nanoslit pair is twice that for an isolated slit. For a broadband source, a compact device with nanoslit separation of the order of a tenth of the wavelength is shown to steer nearly all the generated plasmons to one side for the same phase delay, thereby achieving a broadband unidirectional plasmon launcher. The reported effect can be applied to the design of ultra-broadband and efficient tunable plasmonic devices.

Neural networks using broadband spectral discriminators reduces illumination required for broccoli identification in weedy fields

NASA Astrophysics Data System (ADS)

Hahn, Federico

1996-03-01

Statistical discriminative analysis and neural networks were used to prove that crop/weed/soil discrimination by optical reflectance was feasible. The wavelengths selected as inputs on those neural networks were ten nanometers width, reducing the total collected radiation for the sensor. Spectral data collected from several farms having different weed populations were introduced to discriminant analysis. The best discriminant wavelengths were used to build a wavelength histogram which selected the three best spectral broadbands for broccoli/weed/soil discrimination. The broadbands were analyzed using a new single broadband discriminator index named the discriminative integration index, DII, and the DII values obtained were used to train a neural network. This paper introduces the index concept, its results and its use for minimizing artificial lightning requirements with broadband spectral measurements for broccoli/weed/soil discrimination.

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

NASA Technical Reports Server (NTRS)

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

2011-01-01

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

UHB Engine Fan Broadband Noise Reduction Study

NASA Technical Reports Server (NTRS)

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

1995-01-01

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

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

PubMed

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.

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

NASA Astrophysics Data System (ADS)

Zhang, Haowen; Yang, Qian; Wu, Xuebing; Shen, Yue

2018-01-01

We extended the broadband photometric reverberation mapping (PRM) code, JAVELIN and test the availability to get broad line region (BLR) time delays that are consistent with spectroscopic reverberation mapping (SRM) projects. Broadband light curves of SDSS-RM quasars produced by convolution with system transmission curve were used in the test. We find that under similar sampling conditions (evenly and frequently sampled), the key factor determining whether the broadband PRM code can yield lags consistent with spectroscopic projects is the flux ratio of line to the reference continuum, which is in line with the findings in Zu et al. (2016). We further find a crucial line-to-continuum flux ratio, above which the mean of the ratios between the lags from PRM and SRM becomes closer to unity, and the scatter is pronouncedly reduced. Based on this flux ratio criteria, we selected some of the quasars from Hernitschek et al. (2015) and carry out broadband PRM on this subset. The performance of damped random walking (DRW) model and power-law (PL) structure function model on broadband PRM are compared using mock light curves with high, even cadences and low, uneven ones, respectively. We find that DRW model performs better in carrying out broadband PRM than PL model both for high and low cadence light curves with other data qualities similar to SDSS-RM quasars.

UHB engine fan broadband noise reduction study

NASA Astrophysics Data System (ADS)

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

1995-06-01

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

The Broadband Quandary for Rural America. The Main Street Economist: Commentary on the Rural Economy.

ERIC Educational Resources Information Center

Staihr, Brian

High speed data services known as broadband have the potential to make rural areas less isolated and improve the rural quality of life, but physical barriers, sparse population density, and few markets present significant obstacles to their deployment in rural areas. Broadband applications such as e-commerce, distance education, and telemedicine…

The Feasibility and Value of Broadband Communications in Rural Areas. A Preliminary Evaluation, April 1976.

ERIC Educational Resources Information Center

Mills, William; And Others

The study was conducted to determine the feasibility and value of using broadband communications (transmission of many television, voice and/or data signals through a single system) to provide public services for rural areas. Applications of broadband communications to rural areas were divided into public services (health, education, law…

76 FR 40817 - Implementation of Section 224 of the Act; A National Broadband Plan for Our Future

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-12

...-50] Implementation of Section 224 of the Act; A National Broadband Plan for Our Future AGENCY... information collection requirements. The Office of Management and Budget (OMB) gave approval for these..., Implementation of Section 224 of the Act; A National Broadband Plan for Our Future. DATES: The final rules...

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

ERIC Educational Resources Information Center

Oyana, Tonny J.

2011-01-01

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

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

ERIC Educational Resources Information Center

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…

Community-Based Broadband Solutions: The Benefits of Competition and Choice for Community Development and Highspeed Internet Access

ERIC Educational Resources Information Center

Executive Office of the President, 2015

2015-01-01

Affordable, reliable access to high speed broadband is critical to U.S. economic growth and competitiveness. Upgrading to higher-speed broadband lets consumers use the Internet in new ways, increases the productivity of American individuals and businesses, and drives innovation throughout the digital ecosystem. As this report describes, while the…

Western Cape Subject Advisors' Perception of Their Preparedness for Connected Classrooms

ERIC Educational Resources Information Center

Chigona, Agnes

2017-01-01

In South Africa, the Western Cape government (WCG)'s current broadband strategy aims to ensure that all schools will be connected to broadband service within a reasonable time-frame. According to the WCG integration of ICTs and the broadband will remove the digital divide and enhance curriculum delivery in schools. To achieve this, sensible…

Dynamic Time Multiplexing Fabrication of Holographic Polymer Dispersed Liquid Crystals for Increased Wavelength Sensitivity

NASA Technical Reports Server (NTRS)

Fontecchio, Adam K. (Inventor); Rai, Kashma (Inventor)

2017-01-01

Described herein is a new holographic polymer dispersed liquid crystal (HPDLC) medium with broadband reflective properties, and a new technique for fabrication of broadband HPDLC mediums. The new technique involves dynamic variation of the holography setup during HPDLC formation, enabling the broadening of the HPDLC medium's wavelength response. Dynamic variation of the holography setup may include the rotation and/or translation of one or more motorized stages, allowing for time and spatial, or angular, multiplexing through variation of the incident angles of one or more laser beams on a pre-polymer mixture during manufacture. An HPDLC medium manufactured using these techniques exhibits improved optical response by reflecting a broadband spectrum of wavelengths. A new broadband holographic polymer dispersed liquid crystal thin film polymeric mirror stack with electrically-switchable beam steering capability is disclosed. XXXX Described herein is a new holographic polymer dispersed liquid crystal (HPDLC) medium with broadband reflective properties, and a new technique for fabrication of broadband 10 HPDLC mediums. The new technique involves dynamic variation of the holography setup during HPDLC formation, enabling the broadening of the HPDLC medium's wavelength response. Dynamic variation of the holography setup may include the rotation and/or translation of one or more 15 motorized stages, allowing for time and spatial, or angular, multiplexing through variation of the incident angles of one or more laser beams on a pre-polymer mixture during manufacture. An HPDLC medium manufactured using these techniques exhibits improved optical response by reflecting 20 a broadband spectrum of wavelengths. A new broadband holographic polymer dispersed liquid crystal thin film polymeric mirror stack with electrically switchable beam steering capability is disclosed.

Broadband/Wideband Magnetoelectric Response

DOE PAGES

Park, Chee-Sung; Priya, Shashank

2012-01-01

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

Broadband and broadangle SPP antennas based on plasmonic crystals with linear chirp.

PubMed

Bouillard, J-S; Vilain, S; Dickson, W; Wurtz, G A; Zayats, A V

2012-01-01

Plasmonic technology relies on the coupling of light to surface electromagnetic modes on smooth or structured metal surfaces. While some applications utilise the resonant nature of surface polaritons, others require broadband characteristics. We demonstrate unidirectional and broadband plasmonic antennas with large acceptance angles based on chirped plasmonic gratings. Near-field optical measurements have been used to visualise the excitation of surface plasmon polaritons by such aperiodic structures. These weakly aperiodic plasmonic crystals allow the formation of a trapped rainbow-type effect in a two-dimensional geometry as surface polaritons of different frequencies are coherently excited in different locations over the plasmonic structure. Both the crystal's finite size and the finite lifetime of plasmonic states are crucial for the generation of broadband surface plasmon polaritons. This approach presents new opportunities for building unidirectional, broadband and broad-angle plasmonic couplers for sensing purposes, information processing, photovoltaic applications and shaping and manipulating ultrashort optical pulses.

Evaluation of the annoyance due to helicopter rotor noise

NASA Technical Reports Server (NTRS)

Sternfeld, H., Jr.; Doyle, L. B.

1978-01-01

A program was conducted in which 25 test subjects adjusted the levels of various helicopter rotor spectra until the combination of the harmonic noise and a broadband background noise was judged equally annoying as a higher level of the same broadband noise spectrum. The subjective measure of added harmonic noise was equated to the difference in the two levels of broadband noise. The test participants also made subjective evaluations of the rotor noise signatures which they created. The test stimuli consisted of three degrees of rotor impulsiveness, each presented at four blade passage rates. Each of these 12 harmonic sounds was combined with three broadband spectra and was adjusted to match the annoyance of three different sound pressure levels of broadband noise. Analysis of variance indicated that the important variables were level and impulsiveness. Regression analyses indicated that inclusion of crest factor improved correlation between the subjective measures and various objective or physical measures.

Broadband and broadangle SPP antennas based on plasmonic crystals with linear chirp

PubMed Central

Bouillard, J.-S; Vilain, S.; Dickson, W.; Wurtz, G. A.; Zayats, A. V.

2012-01-01

Plasmonic technology relies on the coupling of light to surface electromagnetic modes on smooth or structured metal surfaces. While some applications utilise the resonant nature of surface polaritons, others require broadband characteristics. We demonstrate unidirectional and broadband plasmonic antennas with large acceptance angles based on chirped plasmonic gratings. Near-field optical measurements have been used to visualise the excitation of surface plasmon polaritons by such aperiodic structures. These weakly aperiodic plasmonic crystals allow the formation of a trapped rainbow-type effect in a two-dimensional geometry as surface polaritons of different frequencies are coherently excited in different locations over the plasmonic structure. Both the crystal's finite size and the finite lifetime of plasmonic states are crucial for the generation of broadband surface plasmon polaritons. This approach presents new opportunities for building unidirectional, broadband and broad-angle plasmonic couplers for sensing purposes, information processing, photovoltaic applications and shaping and manipulating ultrashort optical pulses. PMID:23170197

Making structured metals transparency for broadband and wide-incidence-angle electromagnetic waves

NASA Astrophysics Data System (ADS)

Fan, Renhao; Peng, Ruwen; Huang, Xianrong; Wang, Mu

2014-03-01

Very recently, we have demonstrated that one-dimensional metallic gratings can become transparent and completely antireflective for extremely broadband electromagnetic (EM) waves under oblique incidence. However, the oblique-incidence geometry, is inconvenient for the technological applications. To overcome this drawback, here we instead use oblique metal gratings with optimal tilt angles to achieve normal-incidence broadband transparence for EM waves. Further we use two-dimensional periodic metallic cuboids to achieve broadband and broad-angle high transmission and antireflection. By introducing such metallic cuboids arrays into silicon solar cells, we find that high performance of light trapping in the cells can be obtained with a significant enhancement of the ultimate quantum efficiency. The structured metals, which achieve broadband and broad-angle high transmission for EM waves, may have many other potential applications, such as transparent conducting panels, white-beam polarizers, and stealth objects.

Broadband multiresonator quantum memory-interface.

PubMed

Moiseev, S A; Gerasimov, K I; Latypov, R R; Perminov, N S; Petrovnin, K V; Sherstyukov, O N

2018-03-05

In this paper we experimentally demonstrated a broadband scheme of the multiresonator quantum memory-interface. The microwave photonic scheme consists of the system of mini-resonators strongly interacting with a common broadband resonator coupled with the external waveguide. We have implemented the impedance matched quantum storage in this scheme via controllable tuning of the mini-resonator frequencies and coupling of the common resonator with the external waveguide. Proof-of-principal experiment has been demonstrated for broadband microwave pulses when the quantum efficiency of 16.3% was achieved at room temperature. By using the obtained experimental spectroscopic data, the dynamics of the signal retrieval has been simulated and promising results were found for high-Q mini-resonators in microwave and optical frequency ranges. The results pave the way for the experimental implementation of broadband quantum memory-interface with quite high efficiency η > 0.99 on the basis of modern technologies, including optical quantum memory at room temperature.

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

PubMed

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.

Performance of Complex Spreading MIMO Systems With Interference

DTIC Science & Technology

2011-06-01

14 III. PERFORMANCE ANALYSIS OF DS -PSK MISO ...............................................15 A. SYSTEM DESCRIPTION...15 Figure 9. BER of DS PSK system for broadband jamming and diversity L=1. ..............20 Figure 10. BER of DS PSK system for...broadband jamming and diversity L=2. .............21 Figure 11. BER of DS PSK system for broadband jamming and diversity L=3. ..............22 Figure 12

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

ERIC Educational Resources Information Center

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

2015-01-01

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

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

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-07

....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...

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

PubMed

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.

Bio-inspired heterogeneous composites for broadband vibration mitigation.

PubMed

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.

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

NASA Astrophysics Data System (ADS)

Zhang, Xiupu; Liu, Taijun; Shen, Dongya

2016-12-01

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

Bio-inspired heterogeneous composites for broadband vibration mitigation

NASA Astrophysics Data System (ADS)

Chen, Yanyu; Wang, Lifeng

2015-12-01

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

Broadband set-top box using MAP-CA processor

NASA Astrophysics Data System (ADS)

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

2001-12-01

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

Broadband low-frequency sound isolation by lightweight adaptive metamaterials

NASA Astrophysics Data System (ADS)

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.

Sonic spectrometer and treatment system

DOEpatents

Slomka, B.J.

1997-06-03

A novel system and method is developed for treating an object with sonic waveforms. A traveling broad-band sonic waveform containing a broad-band of sonic frequencies is radiated at the object. A traveling reflected sonic waveform containing sonic frequencies reflected by the object is received in response to the traveling broad-band sonic waveform. A traveling transmitted sonic waveform containing sonic frequencies transmitted through the object is also received in response to the traveling broad-band sonic waveform. In a resonance mode, the frequency spectra of the broad-band and reflected sonic waveforms is analyzed so as to select one or more sonic frequencies that cause the object to resonate. An electrical resonance treatment sonic waveform containing the sonic frequencies that cause the object to resonate is then radiated at the object so as to treat the object. In an absorption mode, the frequency spectra of the electrical broad-band, reflected, and transmitted sonic waveforms is compared so as to select one or more sonic frequencies that are absorbed by the object. An electrical absorption treatment sonic waveform containing the sonic frequencies that are absorbed by the object is then radiated at the object so as to treat the object. 1 fig.

Sonic spectrometer and treatment system

DOEpatents

Slomka, Bogdan J.

1997-06-03

A novel system and method for treating an object with sonic waveforms. A traveling broad-band sonic waveform containing a broad-band of sonic frequencies is radiated at the object. A traveling reflected sonic waveform containing sonic frequencies reflected by the object is received in response to the traveling broad-band sonic waveform. A traveling transmitted sonic waveform containing sonic frequencies transmitted through the object is also received in response to the traveling broad-band sonic waveform. In a resonance mode, the frequency spectra of the broad-band and reflected sonic waveforms is analyzed so as to select one or more sonic frequencies that cause the object to resonate. An electrical resonance treatment sonic waveform containing the sonic frequencies that cause the object to resonate is then radiated at the object so as to treat the object. In an absorption mode, the frequency spectra of the electrical broad-band, reflected, and transmitted sonic waveforms is compared so as to select one or more sonic frequencies that are absorbed by the object. An electrical absorption treatment sonic waveform containing the sonic frequencies that are absorbed by the object is then radiated at the object so as to treat the object.

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

ERIC Educational Resources Information Center

Menon, Siddhartha

2011-01-01

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

Broadband and High power Reactive Jamming Resilient Wireless Communication

DTIC Science & Technology

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

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

ERIC Educational Resources Information Center

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

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

Sensor-guided threat countermeasure system

DOEpatents

Stuart, Brent C.; Hackel, Lloyd A.; Hermann, Mark R.; Armstrong, James P.

2012-12-25

A countermeasure system for use by a target to protect against an incoming sensor-guided threat. The system includes a laser system for producing a broadband beam and means for directing the broadband beam from the target to the threat. The countermeasure system comprises the steps of producing a broadband beam and directing the broad band beam from the target to blind or confuse the incoming sensor-guided threat.

Why Broadband Internet Should Not Be the Priority for Developing Countries

NASA Astrophysics Data System (ADS)

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.

Statistically Based Approach to Broadband Liner Design and Assessment

NASA Technical Reports Server (NTRS)

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

2016-01-01

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

Broadband radiometer

DOEpatents

Cannon, Theodore W.

1994-01-01

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

Broadband radiometer

DOEpatents

Cannon, T.W.

1994-07-26

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

A Theoretical Basis for the Scaling Law of Broadband Shock Noise Intensity in Supersonic Jets

NASA Technical Reports Server (NTRS)

Kandula, Max

2011-01-01

A theoretical basis for the scaling of broadband shock noise intensity In supersonic jets was formulated considering linear shock-shear wave interaction. Modeling of broadband shock noise with the aid of shock-turbulence interaction with special reference to linear theories is briefly reviewed. 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 with the noise generation contribution from off-peak incident angles being relatively unimportant. The proposed hypothesis satisfactorily explains the well-known scaling law for the broadband shock-associated noise in supersonic jets.

Broadband infrared absorbers with stacked double chromium ring resonators

DOE PAGES

Deng, Huixu; Stan, Liliana; Czaplewski, David A.; ...

2017-10-31

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

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

NASA Astrophysics Data System (ADS)

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.

Nonphasematched broadband THz amplification and reshaping in a dispersive chi(3) medium.

PubMed

Koys, Martin; Noskovicova, Eva; Velic, Dusan; Lorenc, Dusan

2017-06-12

We theoretically investigate non-phasematched broadband THz amplification in dispersive chi(3) media. A short 100 fs pump pulse is interacting with a temporally matched second harmonic pulse and a weak THz signal through the four wave mixing process and a significant broadband THz amplification and reshaping is observed. The pulse evolution dynamics is explored by numerically solving a set of generalized Nonlinear Schroedinger equations. The influence of incident pulse chirp, pulse duration and the role of wavelength, THz seed frequency and losses are evaluated separately. It is found that a careful choice of incident parameters can provide a broadband THz output and/or a significant increase of THz peak power.

Non-Foster Circuits for High Performance Antennas: Advantages and Practical Limitations

NASA Astrophysics Data System (ADS)

Jacob, Minu Mariam

The demand for miniaturized, broadband communication systems has created a need for electrically small, broadband antennas. However, all passive electrically small antennas have a fundamental gain-bandwidth limitation related to their electrical size, as first described by Wheeler and Chu. This limitation can be overcome using active non-Foster circuits (negative inductors and/or negative capacitors), which can deliver a broadband input match with active matching techniques, or can help reduce phase dispersion using negative delay effects. This thesis will illustrate the advantages of non-Foster circuits in obtaining broadband small antennas, in addition to examining their practical limitations due to noise in receive applications, and nonlinearity in transmit applications.

Broadband infrared absorbers with stacked double chromium ring resonators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deng, Huixu; Stan, Liliana; Czaplewski, David A.

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

Standardization of Broadband UV Measurements for 365 nm LED Sources

PubMed Central

Eppeldauer, George P.

2012-01-01

Broadband UV measurements are evaluated when UV-A irradiance meters measure optical radiation from 365 nm UV sources. The CIE standardized rectangular-shape UV-A function can be realized only with large spectral mismatch errors. The spectral power-distribution of the 365 nm excitation source is not standardized. Accordingly, the readings made with different types of UV meters, even if they measure the same UV source, can be very different. Available UV detectors and UV meters were measured and evaluated for spectral responsivity. The spectral product of the source-distribution and the meter’s spectral-responsivity were calculated for different combinations to estimate broad-band signal-measurement errors. Standardization of both the UV source-distribution and the meter spectral-responsivity is recommended here to perform uniform broad-band measurements with low uncertainty. It is shown what spectral responsivity function(s) is needed for new and existing UV irradiance meters to perform low-uncertainty broadband 365 nm measurements. PMID:26900516

Broadband Satellite Technologies and Markets Assessed

NASA Technical Reports Server (NTRS)

Wallett, Thomas M.

1999-01-01

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

Broadband Circularly Polarized Patch Antenna and Method

DTIC Science & Technology

2016-09-16

300152 1 of 14 BROADBAND CIRCULARLY POLARIZED PATCH ANTENNA AND METHOD STATEMENT OF GOVERNMENT INTEREST [0001] The invention described herein may...present invention provides a method and apparatus for a broadband circularly polarized patch antenna . (2) Description of the Prior Art [0004] A...patch antenna , also referred to as a microstrip antenna , is a type of radio antenna with a low profile that can be mounted on a flat surface. The

Development of an Autonomous Broadband Acoustic Scattering System for Remote Characterization of Zooplankton

DTIC Science & Technology

2008-01-01

backscatter at a single narrowband frequency, and some AUVs carry single-frequency sidescan sonars (and this technology has been adapted for gliders), the...broadband acoustic scattering system by adapting existing technology that has been recently developed at WHOI for a monostatic Doppler sonar module...broadband acoustic backscattering system: 1) Modifications to the monostatic Doppler sonar module, recently developed at WHOI for turbulence studies

Broadband Impedance Microscopy for Research on Complex Quantum Materials

DTIC Science & Technology

2016-02-08

function in various materials. Figure 2. Sensitivity limit of the broadband impedance microscope (BIM). Figure 3. Preliminary BIM data on YMnO3...2 Statement of the Problem The objective of this DURIP award is to construct a broadband impedance microscope (BIM) for frequency-dependent...platforms and specialized cantilever probes [1] in the PI’s lab, the BIM can now simultaneously obtain microscopic (10 – 100 nm) and quasi- spectroscopic

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

NASA Astrophysics Data System (ADS)

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.

System and method for detection of dispersed broadband signals

DOEpatents

Qian, S.; Dunham, M.E.

1999-06-08

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

System and method for detection of dispersed broadband signals

DOEpatents

Qian, Shie; Dunham, Mark E.

1999-06-08

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

Invited Article: An active terahertz polarization converter employing vanadium dioxide and a metal wire grating in total internal reflection geometry

NASA Astrophysics Data System (ADS)

Liu, Xudong; Chen, Xuequan; Parrott, Edward P. J.; Han, Chunrui; Humbert, Georges; Crunteanu, Aurelian; Pickwell-MacPherson, Emma

2018-05-01

Active broadband terahertz (THz) polarization manipulation devices are challenging to realize, but also of great demand in broadband terahertz systems. Vanadium dioxide (VO2) shows a promising phase transition for active control of THz waves and provides broadband polarization characteristics when integrated within grating-type structures. We creatively combine a VO2-based grating structure with a total internal reflection (TIR) geometry providing a novel interaction mechanism between the electromagnetic waves and the device, to realize a powerful active broadband THz polarization-controlling device. The device is based on a Si-substrate coated with a VO2 layer and a metal grating structure on top, attached to a prism for generating the TIR condition on the Si-VO2-grating interface. The grating is connected to electrodes for electrically switching the VO2 between its insulating and conducting phases. By properly selecting the incident angle of the THz waves, the grating direction, and the incident polarization state, we first achieved a broadband intensity modulator under a fused silica prism with an average modulation depth of 99.75% in the 0.2-1.1 THz region. Additionally, we realized an active ultra-broadband quarter-wave converter under a Si prism that can be switched between a 45° linear rotator and a quarter wave converter in the 0.8-1.5 THz region. This is the first demonstration of an active quarter-wave converter with ultra-broad bandwidth performance. Our work shows a highly flexible and multifunctional polarization-controlling device for broadband THz applications.

Broadband surface plasmon jets: direct observation of plasmon propagation for application to sensors and optical communications in microscale and nanoscale circuitry

DOEpatents

Bouhelier, Alexandre [Westmont, IL; Wiederrecht, Gary P [Elmhurst, IL

2008-02-19

A system and method for generating and using broadband surface plasmons in a metal film for characterization of analyte on or near the metal film. The surface plasmons interact with the analyte and generate leakage radiation which has spectral features which can be used to inspect, identify and characterize the analyte. The broadband plasmon excitation enables high-bandwidth photonic applications.

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

NASA Astrophysics Data System (ADS)

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.

Spectrum Policy in the Age of Broadband: Issues for Congress

DTIC Science & Technology

2010-01-29

smartphones and netbooks ; and cloud computing.31 Introduction of Auctions The FCC, acting on the statutory authority given to it by Congress, has broad...smartphones and netbooks ; and cloud computing. Fixed wireless and Wi-Fi are not new technologies but mobile broadband has given them new roles in meeting...pressroom_overview.php?newsid=770. . Spectrum Policy in the Age of Broadband: Issues for Congress Congressional Research Service 25 Smartphones and Netbooks Two of

Small Business Innovation Research (SBIR) Program FY 1991. Program Solicitation 91.1

DTIC Science & Technology

1990-10-01

battlefield. Technological advances in the development of broadband ECM,ECCM and ESM are required. Multispectral Sensor Technology needs to be developed...such as missiles, aircraft, ground vehicles, artillery and high value assets should be addressed. Smart munitions ECM techniques must be as broadband as... Broadband W-band and Higher RF Medium Power Amplifier NAVAL TRAINING SYSTEMS CENTER N91- 35 High Definition TV Projection Via Single Crystal CRT

Estimation of Tumor Angiogenesis With Contrast Enhanced Subharmonic Ultrasound Imaging

DTIC Science & Technology

2005-07-01

measure the FBV as a function of time (Fig. 1). The setup consists of a pair of confocally positioned broadband focused transducers (diameter: 2.54 cm...signals only come from the microbubbles in the small confocal region of the two transducers (1-4 mm3 for 2 MHz transmission). The sampling frequency...amplified and then supplied to a single-element broadband focused transducer. Another broadband focused transducer ( confocally positioned to the first

Active control and switching of broadband electromagnetically induced transparency in symmetric metadevices

NASA Astrophysics Data System (ADS)

Yahiaoui, Riad; Manjappa, Manukumara; Srivastava, Yogesh Kumar; Singh, Ranjan

2017-07-01

Electromagnetically induced transparency (EIT) arises from coupling between the bright and dark mode resonances that typically involve subwavelength structures with broken symmetry, which results in an extremely sharp transparency band. Here, we demonstrate a tunable broadband EIT effect in a symmetry preserved metamaterial structure at the terahertz frequencies. Alongside, we also envisage a photo-active EIT effect in a hybrid metal-semiconductor metamaterial, where the transparency window can be dynamically switched by shining near-infrared light beam. A robust coupled oscillator model explains the coupling mechanism in the proposed design, which shows a good agreement with the observed results on tunable broadband transparency effect. Such active, switchable, and broadband metadevices could have applications in delay bandwidth management, terahertz filtering, and slow light effects.

Small Vessel Contribution to Underwater Noise

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matzner, Shari; Maxwell, Adam R.; Myers, Joshua R.

2010-12-10

Understanding the types of noise generated by a small boat is important for ensuring that marine ecosystems are protected from detrimental anthropogenic noise. Here we present the results of a field test conducted to examine the effects of engine RPM, number of engines and number of propeller blades on the broadband and narrowband noise produced by a small boat. The test boat was a 23-foot aluminum-hulled boat with dual 100 hp engines. The broadband noise and narrowband peak levels were observed using two hydrophones in different locations. The broadband noise levels were affected by both the number of engines andmore » the RPM; the narrowband peaks showed a greater increase in amplitude with an increase in RPM than the broadband noise levels.« less

Enhancing active and passive remote sensing in the ocean using broadband acoustic transmissions and coherent hydrophone arrays

NASA Astrophysics Data System (ADS)

Tran, Duong Duy

The statistics of broadband acoustic signal transmissions in a random continental shelf waveguide are characterized for the fully saturated regime. The probability distribution of broadband signal energies after saturated multi-path propagation is derived using coherence theory. The frequency components obtained from Fourier decomposition of a broadband signal are each assumed to be fully saturated, where the energy spectral density obeys the exponential distribution with 5.6 dB standard deviation and unity scintillation index. When the signal bandwidth and measurement time are respectively larger than the correlation bandwidth and correlation time of its energy spectral density components, the broadband signal energy obtained by integrating the energy spectral density across the signal bandwidth then follows the Gamma distribution with standard deviation smaller than 5.6 dB and scintillation index less than unity. The theory is verified with broadband transmissions in the Gulf of Maine shallow water waveguide in the 300-1200 Hz frequency range. The standard deviations of received broadband signal energies range from 2.7 to 4.6 dB for effective bandwidths up to 42 Hz, while the standard deviations of individual energy spectral density components are roughly 5.6 dB. The energy spectral density correlation bandwidths of the received broadband signals are found to be larger for signals with higher center frequency. Sperm whales in the New England continental shelf and slope were passively localized, in both range and bearing using a single low-frequency (< 2500 Hz), densely sampled, towed horizontal coherent hydrophone array system. Whale bearings were estimated using time-domain beamforming that provided high coherent array gain in sperm whale click signal-to-noise ratio. Whale ranges from the receiver array center were estimated using the moving array triangulation technique from a sequence of whale bearing measurements. The dive profile was estimated for a sperm whale in the shallow waters of the Gulf of Maine with 160 m water-column depth, located close to the array's near-field where depth estimation was feasible by employing time difference of arrival of the direct and multiply reflected click signals received on the array. The dependence of broadband energy on bandwidth and measurement time was verified employing recorded sperm whale clicks in the Gulf of Maine.

Noise in any frequency range can enhance information transmission in a sensory neuron

NASA Astrophysics Data System (ADS)

Levin, Jacob E.

1997-05-01

The effect of noise on the neural encoding of broadband signals was investigated in the cricket cercal system, a mechanosensory system sensitive to small near-field air particle disturbances. Known air current stimuli were presented to the cricket through audio speakers in a controlled environment in a variety of background noise conditions. Spike trains from the second layer of neuronal processing, the primary sensory interneurons, were recorded with intracellular Electrodes and the performance of these neurons characterized with the tools of information theory. SNR, mutual information rates, and other measures of encoding accuracy were calculated for single frequency, narrowband, and broadband signals over the entire amplitude sensitivity range of the cells, in the presence of uncorrelated noise background also spanning the cells' frequency and amplitude sensitivity range. Significant enhancements of transmitted information through the addition of external noise were observed regardless of the frequency range of either the signal or noise waveforms, provided both were within the operating range of the cell. Considerable improvements in signal encoding were observed for almost an entire order of magnitude of near-threshold signal amplitudes. This included sinusoidal signals embedded in broadband white noise, broadband signals in broadband noise, and even broadband signals presented with narrowband noise in a completely non-overlapping frequency range. The noise related increases in mutual information rate for broadband signals were as high as 150%, and up to 600% increases in SNR were observed for sinusoidal signals. Additionally, it was shown that the amount of information about the signal carried, on average, by each spike was INCREASED for small signals when presented with noise—implying that added input noise can, in certain situations, actually improve the accuracy of the encoding process itself.

Broadband mid-infrared and THz chemical detection with quantum cascade laser multi-heterodyne spectrometers (Conference Presentation)

NASA Astrophysics Data System (ADS)

Westberg, Jonas; Sterczewski, Lukasz A.; Patrick, Link; Wysocki, Gerard

2017-05-01

Majority of chemical species of interest in security and safety applications (e.g. explosives) have complex molecular structures that produce unresolved rotational-vibrational spectroscopic signatures in the mid-infrared. This requires spectroscopic techniques that can provide broadband coverage in the mid-IR region to target broadband absorbers and high resolution to address small molecules that exhibit well-resolved spectral lines. On the other hand, many broadband mid-IR absorbers exhibit well-resolved rotational components in the THz spectral region. Thus, development of spectroscopic sensing technologies that can address both spectral regions is of great importance. Here we demonstrate recent progress towards broadband high-resolution spectroscopic sensing applications with Fabry-Perot quantum cascade lasers (QCLs) and frequency combs using multi-heterodyne spectroscopy (MHS) techniques. In this paper, we will present spectroscopic sensing of large and small molecules in the mid-IR region using QCLs operating at 8.5µm. An example high-resolution, broadband MHS of ammonia (small molecule) and isobutane (broadband absorber) at atmospheric pressure in the 1165-1190 cm^-1 range will be discussed. We have developed a balanced MHS system for mitigation of the laser intensity fluctuations. Absorption spectroscopy as well as dispersion spectroscopy with minimum fractional absorption down to 10^-4/Hz1/2 and fast spectral acquisition capabilities down to 10 µs/spectrum range will be demonstrated. In order to mitigate the shortcomings of the limited chemical selectivity in the mid-IR, THz QCL based spectrometer is currently under development to provide spectral de-congestion and thus significantly improve chemical identification. Preliminary characterization of the performance of THZ QCL combs for the THz QCL-MHS will be presented.

Statistics of multiply scattered broadband terahertz pulses.

PubMed

Pearce, Jeremy; Jian, Zhongping; Mittleman, Daniel M

2003-07-25

We describe the first measurements of the diffusion of broadband single-cycle optical pulses through a highly scattering medium. Using terahertz time-domain spectroscopy, we measure the electric field of a multiply scattered wave with a time resolution shorter than one optical cycle. This time-domain measurement provides information on the statistics of both the amplitude and phase distributions of the diffusive wave. We develop a theoretical description, suitable for broadband radiation, which adequately describes the experimental results.

Large-scale broadband absorber based on metallic tungsten nanocone structure

NASA Astrophysics Data System (ADS)

Wang, Jiaxing; Liang, Yuzhang; Huo, Pengcheng; Wang, Daopeng; Tan, Jun; Xu, Ting

2017-12-01

We report a broadband tungsten absorber based on a nanocone metallic resonant structure fabricated by self-assembly nanosphere lithography. In experimental demonstration, the fabricated absorber has more than 90% average absorption efficiency and shows superior angular tolerance in the entire visible and near-infrared spectral region. We envision that this large-scale nanostructured broadband optical absorber would find great potential in the applications of high performance optoelectronic platforms and solar-thermal energy harvesting systems.

Proceedings of the Antenna Applications Symposium (1988) Volume 1

DTIC Science & Technology

1989-06-01

FIELD GROUP SUB-GROUP Antennas)p Microstrip, ,.Multibeam Antennas 6 Satellite Antennas. Reflector Array Antennas, ____________I____ Broadband Antennas...C. Sullivan and G. E. Evans 8. " Broadband MMIC T/R Module/Subarray Performance," D. Brubaker, 157 D. Scott, S. Ludvik, M. Lynch, H. II. Chung, W...34 S. Sanzgiri, 277 B. Powers, Jr., and J. Hart ib. " broadbanding Techniques for Microstrip Patch Antennas - A ’.93 kReview," K. C. Gupta * NUT INCLUDED

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

NASA Astrophysics Data System (ADS)

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.

Identifying Broadband Rotational Spectra with Neural Networks

NASA Astrophysics Data System (ADS)

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.

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

NASA Astrophysics Data System (ADS)

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.

Mid- and Long-IR Broadband Quantum Well Photodetector

NASA Technical Reports Server (NTRS)

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

2012-01-01

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

Detailed Balance Limit of Efficiency of Broadband-Pumped Lasers.

PubMed

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pala, Ragip A.; Butun, Serkan; Aydin, Koray

2016-09-19

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

Adding seismic broadband analysis to characterize Andean backarc seismicity in Argentina

NASA Astrophysics Data System (ADS)

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.

The use of broadband microseisms for hydraulic fracture mapping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sleefe, G.E.; Warpinski, N.R.; Engler, B.P.

When a hydrocarbon reservoir is subjected to a hydraulic fracture treatment, the cracking and slipping of the formation results in the emission of seismic energy. The objective of this study was to determine the advantages of using broadband (100 Hz to 1500 M) microseismic emissions to map a hydraulic fracture treatment. A hydraulic fracture experiment was performed in the Piceance Basin of Western Colorado to induce and record broadband microseismic events. The formation was subjected to four processes; break-down/ballout, step-rate test, KCL mini-fracture, and linear-gel mini-fracture. Broadband microseisms were successfully recorded by a novel three-component wall-locked seismic accelerometer package, placedmore » in an observation well 211 ft (64 m) offset from the treatment well. During the two hours of formation treatment, more than 1200 significant microseismic events were observed. The occurrences of the events strongly correlated with the injection bore-bole pressures during the treatments. Using both hodogram analysis and time of arrival information, estimates of the origination point of the seismic events were computed. A map of the event locations yielded a fracture orientation estimate consistent with the known orientation of the field in the formation. This paper describes the technique for acquiring and analyzing broadband microseismic events and illustrate how the new broadband approach can enhance signal detectability and event location resolution.« less

47 CFR 27.1203 - EBS programming requirements.

Code of Federal Regulations, 2013 CFR

2013-10-01

... MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27... wired distribution systems or radio facilities authorized under other parts of this chapter, or to...

47 CFR 27.1203 - EBS programming requirements.

Code of Federal Regulations, 2012 CFR

2012-10-01

... MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27... wired distribution systems or radio facilities authorized under other parts of this chapter, or to...

47 CFR 27.1203 - EBS programming requirements.

Code of Federal Regulations, 2014 CFR

2014-10-01

... MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27... wired distribution systems or radio facilities authorized under other parts of this chapter, or to...

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

DOE PAGES

Candy, J. V.

2016-04-14

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

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

NASA Astrophysics Data System (ADS)

Han, Juzheng; Liao, Xiaoping

2017-06-01

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

Broadband thermal optical limiter for the protection of eyes and sensors

NASA Astrophysics Data System (ADS)

Justus, Brian L.; Huston, Alan L.; Campillo, Anthony J.

1994-05-01

A broadband thermal optical limiter for protecting a light sensitive object from intense laser beams at all near ultraviolet, visible and near infrared wavelengths is disclosed. The broadband thermal optical limiter comprises: a sample cell containing a solution of broadband absorber material dissolved in a thermal solvent; and a first optical device for converging an incident laser beam into the sample cell. The sample cell is responsive to a converged incident laser beam below a predetermined intensity level for passing therethrough the converged incident laser beam below the predetermined intensity level. The sample cell is also responsive to a converged incident laser beam at or above a predetermined intensity level for thermally defocusing substantially all of the converged incident laser beam in different directions and passing therethrough only a remaining small portion of the converged incident laser beam at or above the predetermined intensity level. The broadband thermal optical limiter further includes a second optical device for focusing substantially all of the laser beam passing through the sample cell into the light sensitive object to be protected.

Device and method for generating a beam of acoustic energy from a borehole, and applications thereof

DOEpatents

Vu, Cung Khac; Sinha, Dipen N; Pantea, Cristian; Nihei, Kurt T; Schmitt, Denis P; Skelt, Christopher

2013-10-01

In some aspects of the invention, a method of generating a beam of acoustic energy in a borehole is disclosed. The method includes generating a first broad-band acoustic pulse at a first broad-band frequency range having a first central frequency and a first bandwidth spread; generating a second broad-band acoustic pulse at a second broad-band frequency range different than the first frequency range having a second central frequency and a second bandwidth spread, wherein the first acoustic pulse and second acoustic pulse are generated by at least one transducer arranged on a tool located within the borehole; and transmitting the first and the second broad-band acoustic pulses into an acoustically non-linear medium, wherein the composition of the non-linear medium produces a collimated pulse by a non-linear mixing of the first and second acoustic pulses, wherein the collimated pulse has a frequency equal to the difference in frequencies between the first central frequency and the second central frequency and a bandwidth spread equal to the sum of the first bandwidth spread and the second bandwidth spread.

A photoelastic-modulator-based motional Stark effect polarimeter for ITER that is insensitive to polarized broadband background reflections.

PubMed

Thorman, A; Michael, C; De Bock, M; Howard, J

2016-07-01

A motional Stark effect polarimeter insensitive to polarized broadband light is proposed. Partially polarized background light is anticipated to be a significant source of systematic error for the ITER polarimeter. The proposed polarimeter is based on the standard dual photoelastic modulator approach, but with the introduction of a birefringent delay plate, it generates a sinusoidal spectral filter instead of the usual narrowband filter. The period of the filter is chosen to match the spacing of the orthogonally polarized Stark effect components, thereby increasing the effective signal level, but resulting in the destructive interference of the broadband polarized light. The theoretical response of the system to an ITER like spectrum is calculated and the broadband polarization tolerance is verified experimentally.

Generation and parametric amplification of broadband chirped pulses in the near-infrared

NASA Astrophysics Data System (ADS)

Marcinkevičiūtė, A.; Michailovas, K.; Butkus, R.

2018-05-01

We demonstrate generation and optical parametric amplification of broadband chirped pulses in the range of 1.8- 2 . 5 μm. The setup is built around Ti:sapphire oscillator as a seed source and 1 kHz Nd:YAG laser system as a pump source. Visible broadband seed pulses are temporally stretched and amplified in a non-collinear optical parametric amplifier before being mixed with fundamental harmonic of the pump laser. Difference frequency generation between positively-chirped broadband pulses centered at 0 . 7 μm and non-chirped narrowband pulses at 1064 nm produces negatively-chirped wide spectral bandwidth pulses in the infrared. After subsequent parametric amplification, pulses with more than 0.5 mJ energy were obtained with spectral bandwidth supporting transform-limited pulse durations as short as 23 fs.

Reducing broadband shortwave radiometer calibration-bias caused by longwave irradiance in the reference direct beam

DOE PAGES

Reda, Ibrahim; Andreas, Afshin; Dooraghi, Mike; ...

2017-01-13

Shortwave radiometers such as pyranometers, pyrheliometers, and photovoltaic cells are calibrated with traceability to consensus reference, maintained by Absolute Cavity Radiometers (ACRs). The ACR is an open cavity with no window, and measures the extended broadband spectrum of the terrestrial direct solar beam irradiance, unlike shortwave radiometers that cover a limited range of the spectrum. The difference between the two spectral ranges may lead to calibration bias that can exceed 1%. This paper describes a method to reduce the calibration bias resulting from using broadband ACRs to calibrate shortwave radiometers, by using an ACR with Schott glass window to measuremore » the reference broadband shortwave irradiance in the terrestrial direct solar beam from 0.3 um to 3 um.« less

Jet noise modification by the 'whistler nozzle'

NASA Technical Reports Server (NTRS)

Hasan, M. A. Z.; Islam, O.; Hussain, A. K. M. F.

1984-01-01

The farfield noise characteristics of a subsonic whistler nozzle jet are measured as a function of Mach number (0.25, 0.37, and, 0.51), emission angle, and excitation mode. It is shown that a whistler nozzle has greater total and broadband acoustic power than an excited contraction nozzle; and that the intensity of far-field noise is a function of emission angle, Mach number, and whistler excitation stage. The whistler nozzle excitation produces broadband noise amplification with constant spectral shape; the broadband noise amplification (without associated whistler tones and harmonics) increases omnidirectionally with emission angle at all Mach numbers; and the broadband amplification factor decreases as Mach number and emission angle increase. Finally the whistler nozzle is described as a very efficient but inexpensive siren with applications in not only jet excitation but also acoustics.

Broadband changes in the cortical surface potential track activation of functionally diverse neuronal populations

PubMed Central

Miller, Kai J; Honey, Christopher J; Hermes, Dora; Rao, Rajesh PN; denNijs, Marcel; Ojemann, Jeffrey G

2013-01-01

We illustrate a general principal of electrical potential measurements from the surface of the cerebral cortex, by revisiting and reanalyzing experimental work from the visual, language and motor systems. A naïve decomposition technique of electrocorticographic power spectral measurements reveals that broadband spectral changes reliably track task engagement. These broadband changes are shown to be a generic correlate of local cortical function across a variety of brain areas and behavioral tasks. Furthermore, they fit a power-law form that is consistent with simple models of the dendritic integration of asynchronous local population firing. Because broadband spectral changes covary with diverse perceptual and behavioral states on the timescale of 20–50ms, they provide a powerful and widely applicable experimental tool. PMID:24018305

A High-Resolution Study of Quasiperiodic Radio Emissions Observed by the Galileo Plasma Wave Instrument

NASA Technical Reports Server (NTRS)

Menietti, J. D.; Christopher, I.; Granroth, L. J.

2001-01-01

We have conducted a study of quasiperiodic emission observed by the plasma wave instrument on board the Galileo spacecraft. These emissions appear as broadband bursts with dominant periods ranging from 10 min to over 40 min. For these emissions we have explicitly analyzed the high-resolution (waveform) data to determine the presence of impulsive, solitary signatures. Our investigations have indicated that the broadband bursts, as well as the background more narrowband continuum emission, are composed of a highly turbulent spectrum. Within the broadband burst, however, there are higher-frequency components present, but no impulsive electrostatic signatures. Also significantly, the broadband bursts show no low-frequency dispersion. We conclude that the bursts are consistent with a distant, electromagnetic source, probably in the near-Jupiter vicinity.

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

PubMed

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.

Broadband External-Cavity Diode Laser

NASA Technical Reports Server (NTRS)

Pilgrim, Jeffrey S.

2005-01-01

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

Broadband spectral shearing interferometry for amplitude and phase measurement of supercontinua

NASA Astrophysics Data System (ADS)

Dobner, S.; Brauckmann, N.; Kues, M.; Groß, P.; Fallnich, C.

2011-03-01

We present a new concept and the experimental realization of a customized spectral shearing interferometry for direct electric-field reconstruction (SPIDER) that is capable of measuring complex broadband laser pulses. The combination of an adapted broadband non-collinear phase matching geometry and the implementation of a home-built Fourier spectrometer enabled characterization of amplitude and phase of highly structured supercontinua with a bandwidth of more than 200 THz at pulse energies of less than 0.2 nJ.

Broadband mode conversion via gradient index metamaterials

PubMed Central

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

2016-01-01

We propose a design for broadband waveguide mode conversion based on gradient index metamaterials (GIMs). Numerical simulations demonstrate that the zeroth order of transverse magnetic mode or the first order of transverse electric mode (TM0/TE1) can be converted into the first order of transverse magnetic mode or the second order of transverse electric mode (TM1/TE2) for a broadband of frequencies. As an application, an asymmetric propagation is achieved by integrating zero index metamaterials inside the GIM waveguide. PMID:27098456

Integrating Telco interoffice fiber transport with coaxial distribution

NASA Astrophysics Data System (ADS)

McCarthy, Steven M.

1993-02-01

Real success in the residential broadband market is contingent on a platform that most efficiently shares broadband port costs while at the same time affords us an elegant, and cost efficient, upgrade from today's analog to tomorrow's digital world. Spectrum transport, whether it be over new or existing fiber/coax systems or FTTC, is that platform. It is compatible with today's home entertainment market, can be evolved to future digital transport, and effectively shares the cost of interfacing with a broadband network.

Synchrony in broadband fluctuation and the 2008 financial crisis.

PubMed

Lin, Der Chyan

2013-01-01

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

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

PubMed

Buskila, O; Eyal, A; Shtaif, M

2008-03-03

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

Examining Factors Influencing the Behavioral Intention to Adopt Broadband in Malaysia

NASA Astrophysics Data System (ADS)

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.

47 CFR 27.1207 - BTA license authorization.

Code of Federal Regulations, 2011 CFR

2011-10-01

... MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27... Environmental Assessment is required under § 1.1307 of this chapter; (iii) The station would affect the radio...

47 CFR 27.1207 - BTA license authorization.

Code of Federal Regulations, 2014 CFR

2014-10-01

... MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27... Environmental Assessment is required under § 1.1307 of this chapter; (iii) The station would affect the radio...

47 CFR 27.1207 - BTA license authorization.

Code of Federal Regulations, 2013 CFR

2013-10-01

... MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27... Environmental Assessment is required under § 1.1307 of this chapter; (iii) The station would affect the radio...

47 CFR 27.1207 - BTA license authorization.

Code of Federal Regulations, 2010 CFR

2010-10-01

... MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27... Environmental Assessment is required under § 1.1307 of this chapter; (iii) The station would affect the radio...

47 CFR 27.1207 - BTA license authorization.

Code of Federal Regulations, 2012 CFR

2012-10-01

... MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27... Environmental Assessment is required under § 1.1307 of this chapter; (iii) The station would affect the radio...

Combination of broadband diffuse optical spectroscopy with magnetic resonance imaging

NASA Astrophysics Data System (ADS)

Merritt, Sean Isaiah

Broadband diffuse optical spectroscopy (DOS) is an emerging optical technique used to measure absorption and scattering of bulk tissue non-invasively within the near-infrared (600--1050 nm). The ultimate aim of my advisors group is for broadband DOS to become an established medical diagnostic technique used clinically on various tissue types including breast, muscle and bone. The specific goal for my research is to use established magnetic resonance (MR) techniques for the purpose of continued development and validation of broadband DOS. The initial studies carried out were a validation of broadband DOS through a direct comparison with MRI. Both techniques are sensitive to signals produced by water and lipids in tissue. There is also sensitivity to blood flow, which MRI measures using exogenous contrast agents and broadband DOS is sensitive through measurement of total hemoglobin content (THC) and tissue oxygen saturation (StO2). These validation studies were compared initially in a rat tumor model in which both techniques were used simultaneously. A qualitative correlation was found between the MR images of water content and blood perfusion compared with the DOS water and THC values. A more quantitative comparison was made between measuring absolute water and lipid content in phantoms and in human tissue, which showed a strong correlation. The in vivo study also validated that broadband DOS was interrogating bone marrow in the tibia. The second half of this thesis is focused on developing new capabilities of broadband DOS and the MRI literature is used as a guide. When a water molecule hydrogen bonds to another molecule, the absorption spectrum in the near-infrared which is due to the vibrational overtone of the OH bond will change. The expected changes were observed in tissue and an algorithm was developed to fit for a tissue bound water parameter. Also, as tissue temperature changes, the fraction of water bound to other water molecules changes and can be used to fit for deep tissue temperature. Preliminary validation of these two techniques is carried out and there appears to be great potential for these methods.

75 FR 65297 - Submission for OMB Review: Comment Request

Federal Register 2010, 2011, 2012, 2013, 2014

2010-10-22

... to BTOP and the RUS' Broadband Initiatives Program (BIP), the agencies developed BroadbandMatch... needed expertise and resources to strengthen their BTOP and BIP proposals. The long-term success and...

78 FR 25418 - Submission for OMB Review; Comment Request

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-01

.... Burden Hours: 549,776. Needs and Uses: Despite the importance of broadband to the U.S. economy, information about broadband availability was not widely available until this dataset was developed. The data...

Broad-band absorbers for reduction of parasitic light: two alternative solutions

NASA Astrophysics Data System (ADS)

Giovannini, Hughes; Lemarquis, F.; Akhouayri, H.; Cathelinaud, Michel; Torchio, Philippe; Amra, C.; Cousin, Bernard; Laubier, D.; Otrio, Georges

2018-04-01

This paper, "Broad-band absorbers for reduction of parasitic light: two alternative solutions," was presented as part of International Conference on Space Optics—ICSO 1997, held in Toulouse, France.

Broadband Electromagnetic Technology

DOT National Transportation Integrated Search

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 ...

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

PubMed Central

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

2016-01-01

An inexpensive and compact frequency multi-mode diode laser enables a compact two-photon polarization entanglement source via the continuous wave broadband pumped spontaneous parametric down-conversion (SPDC) process. Entanglement degradation caused by polarization mode dispersion (PMD) is one of the critical issues in optical fiber-based polarization entanglement distribution. We theoretically and experimentally investigate how the initial entanglement is degraded when the two-photon polarization entangled state undergoes PMD. We report an effect of PMD unique to broadband pumped SPDC, equally applicable to pulsed pumping as well as cw broadband pumping, which is that the amount of the entanglement degradation is asymmetrical to the PMD introduced to each quantum channel. We believe that our results have important applications in long-distance distribution of polarization entanglement via optical fiber channels. PMID:27174100

Comparison of broadband noise mechanisms, analyses, and experiments on helicopters, propellers, and wind turbines

NASA Technical Reports Server (NTRS)

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

1983-01-01

Experimental data on broadband noise from airfoils are compared, together with analytical methods, in order to identify the mechanisms of noise emission. Rotor noise is categorized into discrete frequency, impulsive, and broadband components, the last having a continuous spectrum originating from a random source. The results of computer simulations of different rotor blade types which produce broadband noise were compared with experimental data and among themselves in terms of predictions of the spectra obtained. Consideration was given to the overall sound pressure level, unsteady turbulence forces, rotational forces, inflow turbulence, self-generated turbulence, and turbulence in the flow. Data are presented for a helicopter rotor and light aircraft propeller. The most significant source was found to be inflow turbulence induced lift fluctuations in helicopter rotors and boundary layer trailing edge noise on large wind energy conversion systems

Broadband unidirectional cloaks based on flat metasurface focusing lenses

NASA Astrophysics Data System (ADS)

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

2015-08-01

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

High-temperature operation of broadband bidirectional terahertz quantum-cascade lasers.

PubMed

Khanal, Sudeep; Gao, Liang; Zhao, Le; Reno, John L; Kumar, Sushil

2016-09-12

Terahertz quantum cascade lasers (QCLs) with a broadband gain medium could play an important role for sensing and spectroscopy since then distributed-feedback schemes could be utilized to produce laser arrays on a single semiconductor chip with wide spectral coverage. QCLs can be designed to emit at two different frequencies when biased with opposing electrical polarities. Here, terahertz QCLs with bidirectional operation are developed to achieve broadband lasing from the same semiconductor chip. A three-well design scheme with shallow-well GaAs/Al0.10Ga0.90As superlattices is developed to achieve high-temperature operation for bidirectional QCLs. It is shown that shallow-well heterostructures lead to optimal quantum-transport in the superlattice for bidirectional operation compared to the prevalent GaAs/Al0.15Ga0.85As material system. Broadband lasing in the frequency range of 3.1-3.7 THz is demonstrated for one QCL design, which achieves maximum operating temperatures of 147 K and 128 K respectively in opposing polarities. Dual-color lasing with large frequency separation is demonstrated for a second QCL, that emits at ~3.7 THz and operates up to 121 K in one polarity, and at ~2.7 THz up to 105 K in the opposing polarity. These are the highest operating temperatures achieved for broadband terahertz QCLs at the respective emission frequencies, and could lead to commercial development of broadband terahertz laser arrays.

High-temperature operation of broadband bidirectional terahertz quantum-cascade lasers

DOE PAGES

Khanal, Sudeep; Gao, Liang; Zhao, Le; ...

2016-09-12

Terahertz quantum cascade lasers (QCLs) with a broadband gain medium could play an important role for sensing and spectroscopy since then distributed-feedback schemes could be utilized to produce laser arrays on a single semiconductor chip with wide spectral coverage. QCLs can be designed to emit at two different frequencies when biased with opposing electrical polarities. Here, we develop terahertz QCLs with bidirectional operation to achieve broadband lasing from the same semiconductor chip. A three-well design scheme with shallow-well GaAs/Al 0.10Ga 0.90As superlattices is developed to achieve high-temperature operation for bidirectional QCLs. It is shown that shallow-well heterostructures lead to optimalmore » quantum-transport in the superlattice for bidirectional operation compared to the prevalent GaAs/Al 0.15Ga 0.85As material system. Furthermore, broadband lasing in the frequency range of 3.1–3.7 THz is demonstrated for one QCL design, which achieves maximum operating temperatures of 147 K and 128 K respectively in opposing polarities. Dual-color lasing with large frequency separation is demonstrated for a second QCL, that emits at ~3.7 THz and operates up to 121 K in one polarity, and at ~2.7 THz up to 105 K in the opposing polarity. Finally, these are the highest operating temperatures achieved for broadband terahertz QCLs at the respective emission frequencies, and could lead to commercial development of broadband terahertz laser arrays.« less

High-temperature operation of broadband bidirectional terahertz quantum-cascade lasers

PubMed Central

Khanal, Sudeep; Gao, Liang; Zhao, Le; Reno, John L.; Kumar, Sushil

2016-01-01

Terahertz quantum cascade lasers (QCLs) with a broadband gain medium could play an important role for sensing and spectroscopy since then distributed-feedback schemes could be utilized to produce laser arrays on a single semiconductor chip with wide spectral coverage. QCLs can be designed to emit at two different frequencies when biased with opposing electrical polarities. Here, terahertz QCLs with bidirectional operation are developed to achieve broadband lasing from the same semiconductor chip. A three-well design scheme with shallow-well GaAs/Al0.10Ga0.90As superlattices is developed to achieve high-temperature operation for bidirectional QCLs. It is shown that shallow-well heterostructures lead to optimal quantum-transport in the superlattice for bidirectional operation compared to the prevalent GaAs/Al0.15Ga0.85As material system. Broadband lasing in the frequency range of 3.1–3.7 THz is demonstrated for one QCL design, which achieves maximum operating temperatures of 147 K and 128 K respectively in opposing polarities. Dual-color lasing with large frequency separation is demonstrated for a second QCL, that emits at ~3.7 THz and operates up to 121 K in one polarity, and at ~2.7 THz up to 105 K in the opposing polarity. These are the highest operating temperatures achieved for broadband terahertz QCLs at the respective emission frequencies, and could lead to commercial development of broadband terahertz laser arrays. PMID:27615416

High-temperature operation of broadband bidirectional terahertz quantum-cascade lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khanal, Sudeep; Gao, Liang; Zhao, Le

Terahertz quantum cascade lasers (QCLs) with a broadband gain medium could play an important role for sensing and spectroscopy since then distributed-feedback schemes could be utilized to produce laser arrays on a single semiconductor chip with wide spectral coverage. QCLs can be designed to emit at two different frequencies when biased with opposing electrical polarities. Here, we develop terahertz QCLs with bidirectional operation to achieve broadband lasing from the same semiconductor chip. A three-well design scheme with shallow-well GaAs/Al 0.10Ga 0.90As superlattices is developed to achieve high-temperature operation for bidirectional QCLs. It is shown that shallow-well heterostructures lead to optimalmore » quantum-transport in the superlattice for bidirectional operation compared to the prevalent GaAs/Al 0.15Ga 0.85As material system. Furthermore, broadband lasing in the frequency range of 3.1–3.7 THz is demonstrated for one QCL design, which achieves maximum operating temperatures of 147 K and 128 K respectively in opposing polarities. Dual-color lasing with large frequency separation is demonstrated for a second QCL, that emits at ~3.7 THz and operates up to 121 K in one polarity, and at ~2.7 THz up to 105 K in the opposing polarity. Finally, these are the highest operating temperatures achieved for broadband terahertz QCLs at the respective emission frequencies, and could lead to commercial development of broadband terahertz laser arrays.« less

Flux and polarization signals of spatially inhomogeneous gaseous exoplanets

NASA Astrophysics Data System (ADS)

Karalidi, T.; Stam, D. M.; Guirado, D.

2013-07-01

Aims: We present numerically calculated, disk-integrated, spectropolarimetric signals of starlight that is reflected by vertically and horizontally inhomogeneous gaseous exoplanets. We include various spatial features that are present on Solar System's gaseous planets: belts and zones, cyclonic spots, and polar hazes, to test whether such features leave traces in the disk-integrated fux and polarization signals. Methods: Broadband flux and polarization signals of starlight that is reflected by gaseous exoplanets are calculated using an efficient, adding-doubling radiative transfer code, that fully includes single and multiple scattering and polarization. The planetary model atmospheres are vertically inhomogeneous and can be horizontally inhomogeneous, and contain gas molecules and/or cloud and/or aerosol particles. Results: The broadband flux and polarization signals are sensitive to cloud top pressures, although in the presence of local pressure differences, such as in belts and clouds, the flux and polarization phase functions have similar shapes as those of horizontally homogeneous planets. Fitting flux phase functions of a planet with belts and zones using a horizontally homogeneous planet could theoretically yield cloud top pressures that differ by a few hundred mbar from those derived from fitting polarization phase functions. In practice, however, observational errors and uncertainties in cloud properties would make such a fit unreliable. A cyclonic spot like Jupiter's Great Red Spot, covering a few percent of the disk, located in equatorial regions, and rotating in and out of the observer's view yields a temporal variation of a few percent in the broadband flux and a few percent in the degree of polarization. Polar hazes leave strong traces in the polarization of reflected starlight in spatially resolved observations, especially seen at phase angles near 90°. Integrated across the planetary disk, polar hazes that cover only part of the planetary disk, change the broadband degree of polarization of the reflected light by a few percent. Such hazes have only small effects on locally reflected broadband fluxes and negligible effects on disk-integrated broadband fluxes. Conclusions: Deriving the presence of belts and zones in the atmospheres of gaseous exoplanets from broadband flux and polarization observations will be extremely difficult. Cyclonic spots could leave temporal changes in the broadband flux and polarization signals of a few percent. Polar hazes that cover a fraction of the planetary disk, and that are composed of small, Rayleigh scattering particles, change the broadband degree of polarization by at most a few percent.

Stable scalable control of soliton propagation in broadband nonlinear optical waveguides

NASA Astrophysics Data System (ADS)

Peleg, Avner; Nguyen, Quan M.; Huynh, Toan T.

2017-02-01

We develop a method for achieving scalable transmission stabilization and switching of N colliding soliton sequences in optical waveguides with broadband delayed Raman response and narrowband nonlinear gain-loss. We show that dynamics of soliton amplitudes in N-sequence transmission is described by a generalized N-dimensional predator-prey model. Stability and bifurcation analysis for the predator-prey model are used to obtain simple conditions on the physical parameters for robust transmission stabilization as well as on-off and off-on switching of M out of N soliton sequences. Numerical simulations for single-waveguide transmission with a system of N coupled nonlinear Schrödinger equations with 2 ≤ N ≤ 4 show excellent agreement with the predator-prey model's predictions and stable propagation over significantly larger distances compared with other broadband nonlinear single-waveguide systems. Moreover, stable on-off and off-on switching of multiple soliton sequences and stable multiple transmission switching events are demonstrated by the simulations. We discuss the reasons for the robustness and scalability of transmission stabilization and switching in waveguides with broadband delayed Raman response and narrowband nonlinear gain-loss, and explain their advantages compared with other broadband nonlinear waveguides.

Energy diffusion controlled reaction rate of reacting particle driven by broad-band noise

NASA Astrophysics Data System (ADS)

Deng, M. L.; Zhu, W. Q.

2007-10-01

The energy diffusion controlled reaction rate of a reacting particle with linear weak damping and broad-band noise excitation is studied by using the stochastic averaging method. First, the stochastic averaging method for strongly nonlinear oscillators under broad-band noise excitation using generalized harmonic functions is briefly introduced. Then, the reaction rate of the classical Kramers' reacting model with linear weak damping and broad-band noise excitation is investigated by using the stochastic averaging method. The averaged Itô stochastic differential equation describing the energy diffusion and the Pontryagin equation governing the mean first-passage time (MFPT) are established. The energy diffusion controlled reaction rate is obtained as the inverse of the MFPT by solving the Pontryagin equation. The results of two special cases of broad-band noises, i.e. the harmonic noise and the exponentially corrected noise, are discussed in details. It is demonstrated that the general expression of reaction rate derived by the authors can be reduced to the classical ones via linear approximation and high potential barrier approximation. The good agreement with the results of the Monte Carlo simulation verifies that the reaction rate can be well predicted using the stochastic averaging method.

Results of the 1986 NASA/FAA/DFVLR main rotor test entry in the German-Dutch wind tunnel (DNW)

NASA Technical Reports Server (NTRS)

Brooks, Thomas F.; Martin, Ruth M.

1987-01-01

An acoustics test of a 40%-scale MBB BO-105 helicopter main rotor was conducted in the Deutsch-Niederlandischer Windkanal (DNW). The research, directed by NASA Langley Research Center, concentrated on the generation and radiation of broadband noise and impulsive blade-vortex interaction (BVI) noise over ranges of pertinent rotor operational envelopes. Both the broadband and BVI experimental phases are reviewed, along with highlights of major technical results. For the broadband portion, significant advancement is the demonstration of the accuracy of prediction methods being developed for broadband self noise, due to boundary layer turbulence. Another key result is the discovery of rotor blade-wake interaction (BWI) as an important contributor to mid frequency noise. Also the DNW data are used to determine for full scale helicopters the relative importance of the different discrete and broadband noise sources. For the BVI test portion, a comprehensive data base documents the BVI impulsive noise character and directionality as functions of rotor flight conditions. The directional mapping of BVI noise emitted from the advancing side as well as the retreating side of the rotor constitutes a major advancement in the understanding of this dominant discrete mechanism.

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

NASA Astrophysics Data System (ADS)

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.

Single-shot spectroscopy of broadband Yb fiber laser

NASA Astrophysics Data System (ADS)

Suzuki, Masayuki; Yoneya, Shin; Kuroda, Hiroto

2017-02-01

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

Modified tandem gratings anastigmatic imaging spectrometer with oblique incidence for spectral broadband

NASA Astrophysics Data System (ADS)

Cui, Chengguang; Wang, Shurong; Huang, Yu; Xue, Qingsheng; Li, Bo; Yu, Lei

2015-09-01

A modified spectrometer with tandem gratings that exhibits high spectral resolution and imaging quality for solar observation, monitoring, and understanding of coastal ocean processes is presented in this study. Spectral broadband anastigmatic imaging condition, spectral resolution, and initial optical structure are obtained based on geometric aberration theory. Compared with conventional tandem gratings spectrometers, this modified design permits flexibility in selecting gratings. A detailed discussion of the optical design and optical performance of an ultraviolet spectrometer with tandem gratings is also included to explain the advantage of oblique incidence for spectral broadband.

Broadband diffractive lens or imaging element

DOEpatents

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

1991-01-01

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

Trans-Pacific Astronomy Experiment Project Status

NASA Technical Reports Server (NTRS)

Hsu, Eddie

2000-01-01

The Trans-Pacific Astronomy Experiment is Phase 2 of the Trans-Pacific High Data Rate Satcom Experiments following the Trans-Pacific High Definition Video Experiment. It is a part of the Global Information Infrastructure-Global Interoperability for Broadband Networks Project (GII-GIBN). Provides global information infrastructure involving broadband satellites and terrestrial networks and access to information by anyone, anywhere, at any time. Collaboration of government, industry, and academic organizations demonstrate the use of broadband satellite links in a global information infrastructure with emphasis on astronomical observations, collaborative discussions and distance learning.

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

NASA Technical Reports Server (NTRS)

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.

Broadband electron spin resonance at low frequency without resonant cavity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jang, Z.; Suh, B.; Corti, M.

2008-04-09

We have developed a nonconventional broadband electron spin resonance (ESR) spectrometer operating continuously in the frequency range from 0.5 to 9 GHz. Dual antenna structure and the microwave absorbing environment differentiate the setup from the conventional one and enable broadband operation with any combination of frequency or magnetic field modulation and frequency or magnetic field sweeping. Its performance has been tested with the measurements on a 1,1-diphenyl-2-picrylhydrazyl (DPPH) sample and with the measurements on the single molecular magnet, V6, in solid state at low temperature.

Investigation of a broadband coherent perfect absorber in a multi-layer structure by using the transfer matrix method

NASA Astrophysics Data System (ADS)

Na, Jihoon; Noh, Heeso

2018-01-01

We investigated a multi-layer structure for a broadband coherent perfect absorber (CPA). The transfer matrix method (TMM) is useful for analyzing the optical properties of structures and optimizing multi-layer structures. The broadband CPA strongly depends on the phase of the light traveling in one direction and the light reflected within the structure. The TMM simulation shows that the absorption bandwidth is increased by 95% in a multi-layer CPA compared to that in a single-layer CPA.

Method for enhancing signals transmitted over optical fibers

DOEpatents

Ogle, James W.; Lyons, Peter B.

1983-01-01

A method for spectral equalization of high frequency spectrally broadband signals transmitted through an optical fiber. The broadband signal input is first dispersed by a grating. Narrow spectral components are collected into an array of equalizing fibers. The fibers serve as optical delay lines compensating for material dispersion of each spectral component during transmission. The relative lengths of the individual equalizing fibers are selected to compensate for such prior dispersion. The output of the equalizing fibers couple the spectrally equalized light onto a suitable detector for subsequent electronic processing of the enhanced broadband signal.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Xue; Liang, Bin, E-mail: liangbin@nju.edu.cn, E-mail: eleqc@nus.edu.sg, E-mail: jccheng@nju.edu.cn; Zou, Xin-ye

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.

Sources, properties, and energization of auroral particle precipitation

NASA Astrophysics Data System (ADS)

Wing, S.; Johnson, J.; Khazanov, G. V.

2017-12-01

The sources of and the physical processes associated with the auroral ion and electron precipitation are studied with DMSP satellites. The electron aurora has been previously classified into three categories: diffuse, monoenergetic, and broadband aurorae. The diffuse auroral electrons can be observed mainly in 22:00 - 09:00 MLT, which coincides much with the spatial distribution of the whistler-mode chorus waves that have been shown to be the predominant mechanism for pitch-angle scattering magnetospheric electrons into the loss cone, but there appears to be a separate population near noon, which may be associated with solar wind particles. The broadband auroral electrons can be found mostly at 22:00 - 02:00 MLT and pre-noon where Alfvén waves, which cause broadband electron acceleration, are observed in the magnetosphere. On the other hand, the monoenergetic auroral electrons can be observed at dusk-midnight sector, pre- and post-noon. The monoenergetic electrons have been previously thought as magnetospheric electrons that have gone through a quasi-static parallel electric field in the upward field-aligned current regions. However, there may be a connection between monoenergetic and broadband electrons in that the low frequency Alfvén wave-electron interaction can result in monoenergetic electron signature. This is consistent with the observations where broadband and monoenergetic electrons are often spatially co-located. Precipitating electrons can ionize the neutrals in the ionosphere, which can travel upward, which can precipitate in the opposite hemisphere or reflected back to the same hemisphere by upward field-aligned potential drop. Either way, the upward flowing electrons can greatly modify the initial precipitating electron population. Substorm processes increase the power of the diffuse, monoenergetic, and broadband electron aurora by 310%, 71%, and 170%, respectively. Substorms energize the ion aurora mainly in the 21:00-05:00 MLT sector. The duration of the substorm cycle for monoenergetic and broadband auroral is 5 hr, but it is larger than 5 hr for diffuse auroral electrons.

77 FR 36406 - Connect America Fund; a National Broadband Plan for Our Future; Establishing Just and Reasonable...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-19

... America Fund; a National Broadband Plan for Our Future; Establishing Just and Reasonable Rates for Local Exchange Carriers; High-Cost Universal Service Support; Correction AGENCY: Federal Communications...

47 CFR 27.1213 - Designated entity provisions for BRS in Commission auctions commencing prior to January 1, 2004.

Code of Federal Regulations, 2014 CFR

2014-10-01

... COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27.1213 Designated entity provisions for BRS in...

47 CFR 27.1213 - Designated entity provisions for BRS in Commission auctions commencing prior to January 1, 2004.

Code of Federal Regulations, 2010 CFR

2010-10-01

... COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27.1213 Designated entity provisions for BRS in...

47 CFR 27.1213 - Designated entity provisions for BRS in Commission auctions commencing prior to January 1, 2004.

Code of Federal Regulations, 2013 CFR

2013-10-01

... COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27.1213 Designated entity provisions for BRS in...

47 CFR 27.1213 - Designated entity provisions for BRS in Commission auctions commencing prior to January 1, 2004.

Code of Federal Regulations, 2011 CFR

2011-10-01

... COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27.1213 Designated entity provisions for BRS in...

47 CFR 27.1235 - Post-transition notification.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 27.1235 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service...) The horizontal and vertical pattern of the antenna; (4) EIRP of the main lobe; (5) Orientation; (6...

High-power Broadband Organic THz Generator

PubMed Central

Jeong, Jae-Hyeok; Kang, Bong-Joo; Kim, Ji-Soo; Jazbinsek, Mojca; Lee, Seung-Heon; Lee, Seung-Chul; Baek, In-Hyung; Yun, Hoseop; Kim, Jongtaek; Lee, Yoon Sup; Lee, Jae-Hyeok; Kim, Jae-Ho; Rotermund, Fabian; Kwon, O-Pil

2013-01-01

The high-power broadband terahertz (THz) generator is an essential tool for a wide range of THz applications. Here, we present a novel highly efficient electro-optic quinolinium single crystal for THz wave generation. For obtaining intense and broadband THz waves by optical-to-THz frequency conversion, a quinolinium crystal was developed to fulfill all the requirements, which are in general extremely difficult to maintain simultaneously in a single medium, such as a large macroscopic electro-optic response and excellent crystal characteristics including a large crystal size with desired facets, good environmental stability, high optical quality, wide transparency range, and controllable crystal thickness. Compared to the benchmark inorganic and organic crystals, the new quinolinium crystal possesses excellent crystal properties and THz generation characteristics with broader THz spectral coverage and higher THz conversion efficiency at the technologically important pump wavelength of 800 nm. Therefore, the quinolinium crystal offers great potential for efficient and gap-free broadband THz wave generation. PMID:24220234

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

NASA Astrophysics Data System (ADS)

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.

Broadband near-field infrared spectroscopy with a high temperature plasma light source.

PubMed

Lahneman, D J; Huffman, T J; Xu, Peng; Wang, S L; Grogan, T; Qazilbash, M M

2017-08-21

Scattering-type scanning near-field optical microscopy (S-SNOM) has enormous potential as a spectroscopy tool in the infrared spectral range where it can probe phonon resonances and carrier dynamics at the nanometer lengths scales. However, its applicability is limited by the lack of practical and affordable table-top light sources emitting intense broadband infrared radiation in the 100 cm -1 to 2,500 cm -1 spectral range. This paper introduces a high temperature plasma light source that is both ultra-broadband and has much more radiant power in the infrared spectral range than conventional, table-top thermal light sources such as the globar. We implement this plasma lamp in our near-field optical spectroscopy set up and demonstrate its capability as a broadband infrared nano-spectroscopy light source by obtaining near-field infrared amplitude and phase spectra of the phonon resonances of SiO 2 and SrTiO 3 .

Intensity tunable infrared broadband absorbers based on VO2 phase transition using planar layered thin films

PubMed Central

Kocer, Hasan; Butun, Serkan; Palacios, Edgar; Liu, Zizhuo; Tongay, Sefaattin; Fu, Deyi; Wang, Kevin; Wu, Junqiao; Aydin, Koray

2015-01-01

Plasmonic and metamaterial based nano/micro-structured materials enable spectrally selective resonant absorption, where the resonant bandwidth and absorption intensity can be engineered by controlling the size and geometry of nanostructures. Here, we demonstrate a simple, lithography-free approach for obtaining a resonant and dynamically tunable broadband absorber based on vanadium dioxide (VO2) phase transition. Using planar layered thin film structures, where top layer is chosen to be an ultrathin (20 nm) VO2 film, we demonstrate broadband IR light absorption tuning (from ~90% to ~30% in measured absorption) over the entire mid-wavelength infrared spectrum. Our numerical and experimental results indicate that the bandwidth of the absorption bands can be controlled by changing the dielectric spacer layer thickness. Broadband tunable absorbers can find applications in absorption filters, thermal emitters, thermophotovoltaics and sensing. PMID:26294085

Broadband planar multilayered absorbers tuned by VO2 phase transition

NASA Astrophysics Data System (ADS)

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

2017-08-01

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

Measurement and correlation of acoustic cavitation with cellular bioeffects.

PubMed

Hallow, Daniel M; Mahajan, Anuj D; McCutchen, Todd E; Prausnitz, Mark R

2006-07-01

Using broadband noise as a measure of cavitation activity, this study determined the kinetics of cavitation during sonication of Optison contrast agent and tested whether cellular bioeffects can be predicted by cavitation dose. Cell suspensions were exposed to ultrasound at varying acoustic frequency, pressure, exposure time, Optison concentration and cell type to obtain a broad range of bioeffects, i.e., intracellular uptake and loss of viability, as quantified by flow cytometry. We found that cavitation activity measured by broadband noise increased and peaked within 20 ms and then decayed with a half-life of tens to hundreds of milliseconds. Intracellular uptake and loss of viability correlated well with the cavitation dose determined by the time integral of broadband noise magnitude. These results demonstrate that broadband noise correlates with bioeffects over a broad range of experimental conditions, which suggests a noninvasive feedback method to control ultrasound's bioeffects in real time.

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

PubMed

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%.

The Digital Divide: A Global View

NASA Astrophysics Data System (ADS)

Ntoko, Alexander

2011-04-01

Huge progress was made in bridging the digital divide in first decade of 21^st century. This was largely due to the explosive growth of mobile, which saw numbers rise from under 500 million to over five billion mobile cellular subscriptions in just ten years. With household mobile penetration rates of over 50% even in rural areas of developing countries, we have achieved the dream of bringing all the world's people within reach of communications technology. We must now, however, replicate the mobile miracle for the Internet, and especially broadband, if we are to avoid creating a new broadband breach to replace the digital divide. Three things need to happen for this to be achieved: firstly, broadband needs to be brought to the top of the development agenda; secondly, broadband needs to become much more affordable and thirdly, security needs to be part of the strategy.

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

NASA Astrophysics Data System (ADS)

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

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

Single crystalline SmB6 nanowires for self-powered, broadband photodetectors covering mid-infrared

NASA Astrophysics Data System (ADS)

Zhou, Yong; Lai, Jiawei; Kong, Lingjian; Ma, Junchao; Lin, Zhu; Lin, Fang; Zhu, Rui; Xu, Jun; Huang, Shiu-Ming; Tang, Dongsheng; Liu, Song; Zhang, Zhensheng; Liao, Zhi-Min; Sun, Dong; Yu, Dapeng

2018-04-01

Self-powered photodetectors with a broadband response have attracted great attention due to their potential applications in sensing, imaging, communication, and spectroscopy. Specifically, those with the detection wavelength range covering mid-infrared at room temperature are very challenging and highly desired. Here, the photoresponse of self-powered SmB6 photodetectors is demonstrated through the spatially resolved photocurrent mapping. The photocurrent originates from the interface between the SmB6 and Au electrodes due to the charge separation by built-in electric fields at the interface. It exhibits a stable photoresponse over broadband wavelengths ranging from 488 nm to 10.6 μm at room-temperature. Our results suggest that the chemical vapor deposition grown SmB6 nanowires could be promising candidates for future broadband self-powered detectors and pave the way toward SmB6-based optoelectronic applications.

High-power broadband organic THz generator.

PubMed

Jeong, Jae-Hyeok; Kang, Bong-Joo; Kim, Ji-Soo; Jazbinsek, Mojca; Lee, Seung-Heon; Lee, Seung-Chul; Baek, In-Hyung; Yun, Hoseop; Kim, Jongtaek; Lee, Yoon Sup; Lee, Jae-Hyeok; Kim, Jae-Ho; Rotermund, Fabian; Kwon, O-Pil

2013-11-13

The high-power broadband terahertz (THz) generator is an essential tool for a wide range of THz applications. Here, we present a novel highly efficient electro-optic quinolinium single crystal for THz wave generation. For obtaining intense and broadband THz waves by optical-to-THz frequency conversion, a quinolinium crystal was developed to fulfill all the requirements, which are in general extremely difficult to maintain simultaneously in a single medium, such as a large macroscopic electro-optic response and excellent crystal characteristics including a large crystal size with desired facets, good environmental stability, high optical quality, wide transparency range, and controllable crystal thickness. Compared to the benchmark inorganic and organic crystals, the new quinolinium crystal possesses excellent crystal properties and THz generation characteristics with broader THz spectral coverage and higher THz conversion efficiency at the technologically important pump wavelength of 800 nm. Therefore, the quinolinium crystal offers great potential for efficient and gap-free broadband THz wave generation.

Broadband and Resonant Approaches to Axion Dark Matter Detection.

PubMed

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 Trailing Edge Noise Predictions in the Time Domain. Revised

NASA Technical Reports Server (NTRS)

Casper, Jay; Farassat, Fereidoun

2003-01-01

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

Broadband sum-frequency generation using d₃₃ in periodically poled LiNbO₃ thin film in the telecommunications band.

PubMed

Li, Guangzhen; Chen, Yuping; Jiang, Haowei; Chen, Xianfeng

2017-03-01

We demonstrate the first, to the best of our knowledge, type-0 broadband sum-frequency generation (SFG) based on single-crystal periodically poled LiNbO₃ (PPLN) thin film. The broad bandwidth property was largely tuned from mid-infrared region to the telecommunications band by engineering the thickness of PPLN from bulk crystal to nanoscale. It provides SFG a solution with both broadband and high efficiency by using the highest nonlinear coefficient d₃₃ instead of d₃₁ in type-I broadband SFG or second-harmonic generation. The measured 3 dB upconversion bandwidth is about 15.5 nm for a 4 cm long single crystal at 1530 nm wavelength. It can find applications in chip-scale spectroscopy, quantum information processing, LiNbO₃-thin-film-based microresonator and optical nonreciprocity devices, etc.

Broadband high-efficiency half-wave plate: a supercell-based plasmonic metasurface approach.

PubMed

Ding, Fei; Wang, Zhuoxian; He, Sailing; Shalaev, Vladimir M; Kildishev, Alexander V

2015-04-28

We design, fabricate, and experimentally demonstrate an ultrathin, broadband half-wave plate in the near-infrared range using a plasmonic metasurface. The simulated results show that the linear polarization conversion efficiency is over 97% with over 90% reflectance across an 800 nm bandwidth. Moreover, simulated and experimental results indicate that such broadband and high-efficiency performance is also sustained over a wide range of incident angles. To further obtain a background-free half-wave plate, we arrange such a plate as a periodic array of integrated supercells made of several plasmonic antennas with high linear polarization conversion efficiency, consequently achieving a reflection-phase gradient for the cross-polarized beam. In this design, the anomalous (cross-polarized) and the normal (copolarized) reflected beams become spatially separated, hence enabling highly efficient and robust, background-free polarization conversion along with broadband operation. Our results provide strategies for creating compact, integrated, and high-performance plasmonic circuits and devices.

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

NASA Astrophysics Data System (ADS)

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.

A predictive model for biomimetic plate type broadband frequency sensor

NASA Astrophysics Data System (ADS)

Ahmed, Riaz U.; Banerjee, Sourav

2016-04-01

In this work, predictive model for a bio-inspired broadband frequency sensor is developed. Broadband frequency sensing is essential in many domains of science and technology. One great example of such sensor is human cochlea, where it senses a frequency band of 20 Hz to 20 KHz. Developing broadband sensor adopting the physics of human cochlea has found tremendous interest in recent years. Although few experimental studies have been reported, a true predictive model to design such sensors is missing. A predictive model is utmost necessary for accurate design of selective broadband sensors that are capable of sensing very selective band of frequencies. Hence, in this study, we proposed a novel predictive model for the cochlea-inspired broadband sensor, aiming to select the frequency band and model parameters predictively. Tapered plate geometry is considered mimicking the real shape of the basilar membrane in the human cochlea. The predictive model is intended to develop flexible enough that can be employed in a wide variety of scientific domains. To do that, the predictive model is developed in such a way that, it can not only handle homogeneous but also any functionally graded model parameters. Additionally, the predictive model is capable of managing various types of boundary conditions. It has been found that, using the homogeneous model parameters, it is possible to sense a specific frequency band from a specific portion (B) of the model length (L). It is also possible to alter the attributes of `B' using functionally graded model parameters, which confirms the predictive frequency selection ability of the developed model.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reda, I.; Konings, J.; Xie, Y.

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

Broadband wireless, integrated services, and their application to intelligent transportation systems

DOT National Transportation Integrated Search

2000-06-01

This paper introduces some of the newer broadband wireless communications alternatives and describes how they could be used to provide high-speed connections between fixed, transportable, and mobile facilities. We also describe the new integrated ser...

47 CFR 8.3 - Transparency.

Code of Federal Regulations, 2013 CFR

2013-10-01

... FEDERAL COMMUNICATIONS COMMISSION GENERAL PRESERVING THE OPEN INTERNET § 8.3 Transparency. A person engaged in the provision of broadband Internet access service shall publicly disclose accurate information regarding the network management practices, performance, and commercial terms of its broadband Internet...

47 CFR 8.3 - Transparency.

Code of Federal Regulations, 2014 CFR

2014-10-01

... FEDERAL COMMUNICATIONS COMMISSION GENERAL PRESERVING THE OPEN INTERNET § 8.3 Transparency. A person engaged in the provision of broadband Internet access service shall publicly disclose accurate information regarding the network management practices, performance, and commercial terms of its broadband Internet...

47 CFR 8.3 - Transparency.

Code of Federal Regulations, 2012 CFR

2012-10-01

... FEDERAL COMMUNICATIONS COMMISSION GENERAL PRESERVING THE OPEN INTERNET § 8.3 Transparency. A person engaged in the provision of broadband Internet access service shall publicly disclose accurate information regarding the network management practices, performance, and commercial terms of its broadband Internet...

47 CFR 27.1206 - Geographic Service Area.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 47 Telecommunication 2 2013-10-01 2013-10-01 false Geographic Service Area. 27.1206 Section 27.1206 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27...

47 CFR 27.1215 - BRS grandfathered leases.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 2 2010-10-01 2010-10-01 false BRS grandfathered leases. 27.1215 Section 27.1215 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27...

47 CFR 27.1215 - BRS grandfathered leases.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 2 2011-10-01 2011-10-01 false BRS grandfathered leases. 27.1215 Section 27.1215 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27...

47 CFR 27.1210 - Remote control operation.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 47 Telecommunication 2 2013-10-01 2013-10-01 false Remote control operation. 27.1210 Section 27.1210 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27...

47 CFR 27.1215 - BRS grandfathered leases.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 47 Telecommunication 2 2013-10-01 2013-10-01 false BRS grandfathered leases. 27.1215 Section 27.1215 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27...

47 CFR 27.1210 - Remote control operation.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 2 2010-10-01 2010-10-01 false Remote control operation. 27.1210 Section 27.1210 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27...

47 CFR 27.1210 - Remote control operation.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 47 Telecommunication 2 2012-10-01 2012-10-01 false Remote control operation. 27.1210 Section 27.1210 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27...

47 CFR 27.1206 - Geographic Service Area.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 47 Telecommunication 2 2012-10-01 2012-10-01 false Geographic Service Area. 27.1206 Section 27.1206 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27...

47 CFR 27.1218 - Designated entities.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 47 Telecommunication 2 2014-10-01 2014-10-01 false Designated entities. 27.1218 Section 27.1218 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27.1218 Designated entities...

47 CFR 27.1211 - Unattended operation.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 2 2011-10-01 2011-10-01 false Unattended operation. 27.1211 Section 27.1211 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27.1211 Unattended operation...

47 CFR 27.1211 - Unattended operation.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 2 2010-10-01 2010-10-01 false Unattended operation. 27.1211 Section 27.1211 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27.1211 Unattended operation...

47 CFR 27.1210 - Remote control operation.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 2 2011-10-01 2011-10-01 false Remote control operation. 27.1210 Section 27.1210 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27...

47 CFR 27.1218 - Designated entities.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 47 Telecommunication 2 2013-10-01 2013-10-01 false Designated entities. 27.1218 Section 27.1218 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27.1218 Designated entities...

47 CFR 27.1206 - Geographic Service Area.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 2 2011-10-01 2011-10-01 false Geographic Service Area. 27.1206 Section 27.1206 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27...

47 CFR 27.1215 - BRS grandfathered leases.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 47 Telecommunication 2 2014-10-01 2014-10-01 false BRS grandfathered leases. 27.1215 Section 27.1215 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27...

47 CFR 27.1211 - Unattended operation.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 47 Telecommunication 2 2012-10-01 2012-10-01 false Unattended operation. 27.1211 Section 27.1211 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27.1211 Unattended operation...

47 CFR 27.1210 - Remote control operation.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 47 Telecommunication 2 2014-10-01 2014-10-01 false Remote control operation. 27.1210 Section 27.1210 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27...

47 CFR 27.1211 - Unattended operation.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 47 Telecommunication 2 2013-10-01 2013-10-01 false Unattended operation. 27.1211 Section 27.1211 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27.1211 Unattended operation...

47 CFR 27.1211 - Unattended operation.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 47 Telecommunication 2 2014-10-01 2014-10-01 false Unattended operation. 27.1211 Section 27.1211 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27.1211 Unattended operation...

47 CFR 27.1206 - Geographic Service Area.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 47 Telecommunication 2 2014-10-01 2014-10-01 false Geographic Service Area. 27.1206 Section 27.1206 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27...

47 CFR 8.3 - Transparency.

Code of Federal Regulations, 2011 CFR

2011-10-01

... FEDERAL COMMUNICATIONS COMMISSION GENERAL PRESERVING THE OPEN INTERNET § 8.3 Transparency. A person engaged in the provision of broadband Internet access service shall publicly disclose accurate information regarding the network management practices, performance, and commercial terms of its broadband Internet...

Are You Neutral About Net Neutrality

DTIC Science & Technology

2007-06-20

Alaska War on Terrorism Universal Service Reform Streamlining Franchising Process Video Content Municipal Broadband Wireless Innovation Networks Digital...Chair, Joe Barton (R), Texas National Video Franchising Network Neutrality/Enforcement of Broadband Policy VoIP/E9ll Municipal Provision of Services

Expressive Communication and Human Development in the New Broadband Environment

ERIC Educational Resources Information Center

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.

47 CFR 20.12 - Resale and roaming.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES COMMERCIAL MOBILE RADIO... section is applicable to providers of Broadband Personal Communications Services (part 24, subpart E of... requirements of that paragraph those Broadband Personal Communications Services C, D, E, and F block licensees...

75 FR 35765 - Proposed Information Collection; Comment Request; BroadbandMatch Web Site Tool

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-23

... DEPARTMENT OF COMMERCE National Telecommunications and Information Administration Proposed Information Collection; Comment Request; BroadbandMatch Web Site Tool AGENCY: National Telecommunications and Information Administration, Commerce. ACTION: Notice. SUMMARY: The Department of Commerce, as part of its...

47 CFR 8.7 - No unreasonable discrimination.

Code of Federal Regulations, 2014 CFR

2014-10-01

... Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL PRESERVING THE OPEN INTERNET § 8.7 No unreasonable discrimination. A person engaged in the provision of fixed broadband Internet access service, insofar as such... consumer's broadband Internet access service. Reasonable network management shall not constitute...

47 CFR 8.7 - No unreasonable discrimination.

Code of Federal Regulations, 2012 CFR

2012-10-01

... Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL PRESERVING THE OPEN INTERNET § 8.7 No unreasonable discrimination. A person engaged in the provision of fixed broadband Internet access service, insofar as such... consumer's broadband Internet access service. Reasonable network management shall not constitute...

47 CFR 27.1212 - License term.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 2 2010-10-01 2010-10-01 false License term. 27.1212 Section 27.1212 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27.1212 License term. (a) BRS...

47 CFR 27.1212 - License term.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 2 2011-10-01 2011-10-01 false License term. 27.1212 Section 27.1212 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27.1212 License term. (a) BRS...

47 CFR 27.1212 - License term.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 47 Telecommunication 2 2014-10-01 2014-10-01 false License term. 27.1212 Section 27.1212 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27.1212 License term. (a) BRS...

47 CFR 27.1212 - License term.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 47 Telecommunication 2 2012-10-01 2012-10-01 false License term. 27.1212 Section 27.1212 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27.1212 License term. (a) BRS...

47 CFR 27.1212 - License term.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 47 Telecommunication 2 2013-10-01 2013-10-01 false License term. 27.1212 Section 27.1212 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27.1212 License term. (a) BRS...

47 CFR 8.7 - No Unreasonable Discrimination.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL PRESERVING THE OPEN INTERNET § 8.7 No Unreasonable Discrimination. A person engaged in the provision of fixed broadband Internet access service, insofar as such... consumer's broadband Internet access service. Reasonable network management shall not constitute...

76 FR 74721 - Preserving the Open Internet

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-01

...; Report No. 2936] Preserving the Open Internet AGENCY: Federal Communications Commission. ACTION: Final... for broadband service to preserve and reinforce Internet freedom and openness. DATES: Oppositions to... applicability. Subject: In the Matter of Preserving the Open Internet, Broadband Industry Practices, published...

47 CFR 90.528 - Public safety broadband license.

Code of Federal Regulations, 2011 CFR

2011-10-01

... licensed if: (i) International agreements require coordination; (ii) Submission of an environmental... 47 Telecommunication 5 2011-10-01 2011-10-01 false Public safety broadband license. 90.528 Section 90.528 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO...

Broadband astigmatism-corrected spectrometer design using a toroidal lens and a special filter

NASA Astrophysics Data System (ADS)

Ge, Xianying; Chen, Siying; Zhang, Yinchao; Chen, He; Guo, Pan; Mu, Taotao; Yang, Jian; Bu, Zhichao

2015-01-01

In the paper, a method to obtain a broadband, astigmatism-corrected spectrometer based on the existing Czerny-Turner spectrometer is proposed. The theories of astigmatism correction using a toroidal lens and a special filter are described in detail. Performance comparisons of the modified spectrometer and the traditional spectrometer are also presented. Results show that with the new design the RMS spot radius in sagittal view is one-eightieth of that in the traditional spectrometer over a broadband spectral range from 300 to 700 nm, without changing or moving any optical elements in the traditional spectrometer.

Near-infrared resonance-mediated chirp control of a coherently generated broadband deep-ultraviolet spectrum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rybak, Leonid; Chuntonov, Lev; Gandman, Andrey

2011-09-15

We investigate the use of shaped near-infrared (NIR) femtosecond pulses to control the generation of coherent broadband deep-ultraviolet (DUV) radiation in an atomic resonance-mediated (2+1) three-photon excitation to a broad far-from-resonance continuum. Previously, we have shown control over the total emitted DUV yield. Here, we experimentally demonstrate phase control over the spectral characteristics (central frequency and bandwidth) of the emitted broadband DUV radiation. It is achieved by tuning the linear chirp applied to the exciting NIR femtosecond pulse. The study is conducted with Na vapor.

An analytical parametric study of the broadband noise from axial-flow fans

NASA Technical Reports Server (NTRS)

Chou, Shau-Tak; George, Albert R.

1987-01-01

The rotating dipole analysis of Ffowcs Williams and Hawkings (1969) is used to predict the far field noise radiation due to various rotor broadband noise mechanisms. Consideration is given to inflow turbulence noise, attached boundary layer/trailing-edge interaction noise, tip-vortex formation noise, and trailing-edge thickness noise. The parametric dependence of broadband noise from unducted axial-flow fans on several critical variables is studied theoretically. The angle of attack of the rotor blades, which is related to the rotor performance, is shown to be important to the trailing-edge noise and to the tip-vortex formation noise.

Broadband diffractive lens or imaging element

DOEpatents

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

1993-01-01

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

Broadband diffractive lens or imaging element

DOEpatents

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

1993-10-26

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

Experimental demonstration of quantum teleportation of broadband squeezing.

PubMed

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

2007-09-14

We demonstrate an unconditional high-fidelity teleporter capable of preserving the broadband entanglement in an optical squeezed state. In particular, we teleport a squeezed state of light and observe -0.8+/-0.2 dB of squeezing in the teleported (output) state. We show that the squeezing criterion translates directly into a sufficient criterion for entanglement of the upper and lower sidebands of the optical field. Thus, this result demonstrates the first unconditional teleportation of broadband entanglement. Our teleporter achieves sufficiently high fidelity to allow the teleportation to be cascaded, enabling, in principle, the construction of deterministic non-Gaussian operations.

Techniques Analysis of the Interference Suppression Algorithm in Broadband Aeronautical Multi-carrier Communication System

NASA Astrophysics Data System (ADS)

Li, Dong-xia; Ye, Qian-wen

Out-of-band radiation suppression algorithm must be used efficiently for broadband aeronautical communication system in order not to interfere the operation of the existing systems in aviation L-Band. Based on the simple introduction of the broadband aeronautical multi-carrier communication (B-AMC) system model, several sidelobe suppression techniques in orthogonal frequency multiplexing (OFDM) system are presented and analyzed so as to find a suitable algorithm for B-AMC system in this paper. Simulation results show that raise-cosine function windowing can suppress the out-of-band radiation of B-AMC system effectively.

Array Of Sensors Measures Broadband Radiation

NASA Technical Reports Server (NTRS)

Hoffman, James W.; Grush, Ronald G.

1994-01-01

Multiple broadband radiation sensors aimed at various portions of total field of view. All sensors mounted in supporting frame, serving as common heat sink and temperature reference. Each sensor includes heater winding and differential-temperature-sensing bridge circuit. Power in heater winding adjusted repeatedly in effort to balance bridge circuit. Intended to be used aboard satellite in orbit around Earth to measure total radiation emitted, at various viewing angles, by mosaic of "footprint" areas (each defined by its viewing angle) on surface of Earth. Modified versions of array useful for angle-resolved measurements of broadband radiation in laboratory and field settings on Earth.

Rare-Earth Oxide Ion (Tm3+, Ho3+, and U3+) Doped Glasses and Fibres for 1.8 to 4 Micrometer Coherent and Broadband Sources

DTIC Science & Technology

2006-07-24

oxide ( TeO2 ) , fluorine- containing silicate (SiOF2) and germanate (GeOF2) glass hosts for each dopant by characterising the spectroscopic properties...Earth Oxide Ion (Tm3+, Ho3+, And U3+) Doped Glasses And Fibres For 1.8 To 4 Micrometer Coherent And Broadband Sources 5c. PROGRAM ELEMENT NUMBER 5d...Rare-earth oxide ion (Tm3+, Ho3+, and U3+) doped glasses and fibres for 1.8 to 4 micrometer coherent and broadband sources Report prepared

Method for enhancing signals transmitted over optical fibers

DOEpatents

Ogle, J.W.; Lyons, P.B.

1981-02-11

A method for spectral equalization of high frequency spectrally broadband signals transmitted through an optical fiber is disclosed. The broadband signal input is first dispersed by a grating. Narrow spectral components are collected into an array of equalizing fibers. The fibers serve as optical delay lines compensating for material dispersion of each spectral component during transmission. The relative lengths of the individual equalizing fibers are selected to compensate for such prior dispersion. The output of the equalizing fibers couple the spectrally equalized light onto a suitable detector for subsequent electronic processing of the enhanced broadband signal.

Fan Noise Source Diagnostic Test: Vane Unsteady Pressure Results

NASA Technical Reports Server (NTRS)

Envia, Edmane

2002-01-01

To investigate the nature of fan outlet guide vane pressure fluctuations and their link to rotor-stator interaction noise, time histories of vane fluctuating pressures were digitally acquired as part of the Fan Noise Source Diagnostic Test. Vane unsteady pressures were measured at seven fan tip speeds for both a radial and a swept vane configuration. Using time-domain averaging and spectral analysis, the blade passing frequency (BPF) harmonic and broadband contents of the vane pressures were individually analyzed. Significant Sound Pressure Level (SPL) reductions were observed for the swept vane relative to the radial vane for the BPF harmonics of vane pressure, but vane broadband reductions due to sweep turned out to be much smaller especially on an average basis. Cross-correlation analysis was used to establish the level of spatial coherence of broadband pressures between different locations on the vane and integral length scales of pressure fluctuations were estimated from these correlations. Two main results of this work are: (1) the average broadband level on the vane (in dB) increases linearly with the fan tip speed for both the radial and swept vanes, and (2) the broadband pressure distribution on the vane is nearly homogeneous and its integral length scale is a monotonically decreasing function of fan tip speed.

Combined dispersive/interference spectroscopy for producing a vector spectrum

DOEpatents

Erskine, David J.

2002-01-01

A method of measuring the spectral properties of broadband waves that combines interferometry with a wavelength disperser having many spectral channels to produce a fringing spectrum. Spectral mapping, Doppler shifts, metrology of angles, distances and secondary effects such as temperature, pressure, and acceleration which change an interferometer cavity length can be measured accurately by a compact instrument using broadband illumination. Broadband illumination avoids the fringe skip ambiguities of monochromatic waves. The interferometer provides arbitrarily high spectral resolution, simple instrument response, compactness, low cost, high field of view and high efficiency. The inclusion of a disperser increases fringe visibility and signal to noise ratio over an interferometer used alone for broadband waves. The fringing spectrum is represented as a wavelength dependent 2-d vector, which describes the fringe amplitude and phase. Vector mathematics such as generalized dot products rapidly computes average broadband phase shifts to high accuracy. A Moire effect between the interferometer's sinusoidal transmission and the illumination heterodynes high resolution spectral detail to low spectral detail, allowing the use of a low resolution disperser. Multiple parallel interferometer cavities of fixed delay allow the instantaneous mapping of a spectrum, with an instrument more compact for the same spectral resolution than a conventional dispersive spectrometer, and not requiring a scanning delay.

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

NASA Astrophysics Data System (ADS)

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.

Modeling of Broadband Liners Applied to the Advanced Noise Control Fan

NASA Technical Reports Server (NTRS)

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

2015-01-01

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

The MOBB experiment: A prototype permanent off-shore ocean bottom broadband station

NASA Astrophysics Data System (ADS)

Romanowicz, Barbara; Stakes, Debra; Uhrhammer, Robert; McGill, Paul; Neuhauser, Doug; Ramirez, Tony; Dolenc, David

Technical accomplishments of the past 10 years in the design and deployment of sea floor broadband seismic systems are now making it possible to start addressing the issue of the limited coverage of the Earth that can be achieved through land-based installations, at the regional or global scale. In particular, the September 2002 Ocean Mantle Dynamics (OMD) workshop in Snowbird, Utah [OMD Workshop Committee, 2003] proposed the development of two “leap-frogging arrays” of about 30 broadband sea floor instruments to fill geophysically important target holes in ocean coverage for deployment periods of 1 to 2 years. The rationale for an off-shore (“Webfoot”) component of the SArray/Earth-scope “Bigfoot” array was also highlighted at this meeting, pointing out that the study of the North American continent should not stop at the ocean margin.The ocean floor environment is challenging for broadband seismology for several reasons. Broadband seismometers cannot be simply “dropped off” a ship with the expectation that they will produce useable data, particularly on the horizontal components. Several pilot experiments, [e.g., Montagner et al., 1994; OSN1, 1998; Suyehiro et al., 2002] have addressed the issue of optimal installation of ocean bottom stations, and in particular, have carried out comparisons between borehole, sea floor, and buried sea floor installations.

Omnidirectional, broadband light absorption using large-area, ultrathin lossy metallic film coatings

NASA Astrophysics Data System (ADS)

Li, Zhongyang; Palacios, Edgar; Butun, Serkan; Kocer, Hasan; Aydin, Koray

2015-10-01

Resonant absorbers based on nanostructured materials are promising for variety of applications including optical filters, thermophotovoltaics, thermal emitters, and hot-electron collection. One of the significant challenges for such micro/nanoscale featured medium or surface, however, is costly lithographic processes for structural patterning which restricted from industrial production of complex designs. Here, we demonstrate lithography-free, broadband, polarization-independent optical absorbers based on a three-layer ultrathin film composed of subwavelength chromium (Cr) and oxide film coatings. We have measured almost perfect absorption as high as 99.5% across the entire visible regime and beyond (400-800 nm). In addition to near-ideal absorption, our absorbers exhibit omnidirectional independence for incidence angle over ±60 degrees. Broadband absorbers introduced in this study perform better than nanostructured plasmonic absorber counterparts in terms of bandwidth, polarization and angle independence. Improvements of such “blackbody” samples based on uniform thin-film coatings is attributed to extremely low quality factor of asymmetric highly-lossy Fabry-Perot cavities. Such broadband absorber designs are ultrathin compared to carbon nanotube based black materials, and does not require lithographic processes. This demonstration redirects the broadband super absorber design to extreme simplicity, higher performance and cost effective manufacturing convenience for practical industrial production.

Relativistic runaway breakdown in low-frequency radio

NASA Astrophysics Data System (ADS)

Füllekrug, Martin; Roussel-Dupré, Robert; Symbalisty, Eugene M. D.; Chanrion, Olivier; Odzimek, Anna; van der Velde, Oscar; Neubert, Torsten

2010-01-01

The electromagnetic radiation emitted by an electron avalanche beam resulting from relativistic runaway breakdown within the Earth's atmosphere is investigated. It is found from theoretical modeling with a computer simulation that the electron beam emits electromagnetic radiation which is characterized by consecutive broadband pulses in the low-frequency radio range from ˜10 to 300 kHz at a distance of ˜800 km. Experimental evidence for the existence of consecutive broadband pulses is provided by low-frequency radio observations of sprite-producing lightning discharges at a distance of ˜550 km. The measured broadband pulses occur ˜4-9 ms after the sprite-producing lightning discharge, they exhibit electromagnetic radiation which mainly spans the frequency range from ˜50 to 350 kHz, and they exhibit complex waveforms without the typical ionospheric reflection of the first hop sky wave. Two consecutive pulses occur ˜4.5 ms and ˜3 ms after the causative lightning discharge and coincide with the sprite luminosity. It is concluded that relativistic runaway breakdown within the Earth's atmosphere can emit broadband electromagnetic pulses and possibly generates sprites. The source location of the broadband pulses can be determined with an interferometric network of wideband low-frequency radio receivers to lend further experimental support to the relativistic runaway breakdown theory.

Broadband Analysis of the Energetics of Earthquakes and Tsunamis in the Sunda Forearc from 1987-2012

NASA Astrophysics Data System (ADS)

Choy, G. L.; Kirby, S. H.; Hayes, G. P.

2013-12-01

In the eighteen years before the 2004 Sumatra Mw 9.1 earthquake, the forearc off Sumatra experienced only one large (Mw > 7.0) thrust event and experienced no earthquakes that generated measurable tsunami wave heights. In the subsequent eight years, twelve large thrust earthquakes occurred of which half generated measurable tsunamis. The number of broadband earthquakes (those events with Mw > 5.5 for which broadband teleseismic waveforms have sufficient signal to compute depths, focal mechanisms, moments and radiated energies) jumped six fold after 2004. The progression of tsunami earthquakes, as well as the profuse increase in broadband activity, strongly suggests regional stress adjustments following the Sumatra 2004 megathrust earthquake. Broadband source parameters, published routinely in the Source Parameters (SOPAR) database of the USGS's NEIC (National Earthquake Information Center), have provided the most accurate depths and locations of big earthquakes since the implementation of modern digital seismographic networks. Moreover, radiated energy and seismic moment (also found in SOPAR) are related to apparent stress which is a measure of fault maturity. In mapping apparent stress as a function of depth and focal mechanism, we find that about 12% of broadband thrust earthquakes in the subduction zone are unequivocally above or below the slab interface. Apparent stresses of upper-plate events are associated with failure on mature splay faults, some of which generated measurable tsunamis. One unconventional source for local wave heights was a large intraslab earthquake. High-energy upper-plate events, which are dominant in the Aceh Basin, are associated with immature faults, which may explain why the region was bypassed by significant rupture during the 2004 Sumatra earthquake. The majority of broadband earthquakes are non-randomly concentrated under the outer-arc high. They appear to delineate the periphery of the contiguous rupture zones of large earthquakes. A not uncommon occurrence at the outer-arc high is that of a large (Mw >7.0) earthquake followed by another event, also of large magnitude, in very close spatial (<50 km) proximity within a short time (days to months). The physical separation between these events provides constraints on the nature of barriers to rupture propagation. Some of the glaring disparities in seismic damage and tsunami excitation for earthquakes with the same magnitude can be attributed to differences between rupture properties landward and seaward of the outer-arc high. Although most of the studied broadband earthquakes occurred in the wake of the Sumatra 2004 megathrust event, they illuminate tectonic features that exert a strong influence on rupture growth and extent. The application of broadband analysis to other island arcs will complement current criteria for evaluating seismic and tsunami potential

47 CFR 27.1233 - Reimbursement costs of transitioning.

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2010-10-01

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7 CFR 1738.16 - Eligible entities.

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2010-01-01

... 7 Agriculture 11 2010-01-01 2010-01-01 false Eligible entities. 1738.16 Section 1738.16... Eligible entities. (a) RUS makes broadband loans to legally organized entities providing, or proposing to provide, broadband services in eligible rural communities. (1) Types of eligible entities include...

7 CFR 1738.16 - Eligible entities.

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2010-05-24

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47 CFR 1.9005 - Included services.

Code of Federal Regulations, 2011 CFR

2011-10-01

... following services, which include Wireless Radio Services in which commercial or private licensees hold...) The broadband Personal Communications Service (part 24 of this chapter); (h) The Broadband Radio...) The Wireless Communications Service in the 698-746 MHz band (part 27 of this chapter); (k) The...

47 CFR 27.1208 - BTA service areas.

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2012-10-01

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47 CFR 27.1216 - Grandfathered E and F group EBS licenses.

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2014-10-01

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47 CFR 27.1216 - Grandfathered E and F group EBS licenses.

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

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-09

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2013-10-01

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47 CFR 24.239 - Cost-sharing requirements for broadband PCS.

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2014-10-01

... SERVICES PERSONAL COMMUNICATIONS SERVICES Broadband PCS Policies Governing Microwave Relocation from the...) are required to relocate the existing Fixed Microwave Services (FMS) licensees in these bands if... by other PCS entities or a voluntarily relocating microwave incumbent, must contribute to such...

47 CFR 24.239 - Cost-sharing requirements for broadband PCS.

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2010-10-01

... SERVICES PERSONAL COMMUNICATIONS SERVICES Broadband PCS Policies Governing Microwave Relocation from the...) are required to relocate the existing Fixed Microwave Services (FMS) licensees in these bands if... by other PCS entities or a voluntarily relocating microwave incumbent, must contribute to such...

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2011-10-01

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Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-11

... good example of an enabling Smart Grid technology that can empower both utilities and consumers to... Information and Communication Technologies (ICT) sector by integrating broadband into the developing Smart...'s years [[Page 26204

Waveguide modes in sparse III-V nanowire arrays for ultra-broadband tunable perfect absorbers (Conference Presentation)

NASA Astrophysics Data System (ADS)

Fountaine, Katherine T.; Cheng, Wen-Hui; Bukowsky, Colton R.; Atwater, Harry A.

2016-09-01

Design of perfect absorbers and emitters has been a primary focus of the metamaterials community owing to their potential to enhance device efficiency and sensitivity in energy harvesting and sensing applications, specifically photovoltaics, thermal emission control, bolometers and photodetectors, to name a few. While reports of perfect absorbers/emitters for a specific frequency, wavevector, and polarization are ubiquitous, a broadband and polarization- and angle-insensitive perfect absorber remains a particular challenge. In this work, we report on directed optical design and fabrication of sparse III-V nanowire arrays as broadband, polarization- and angle-insensitive perfect absorbers and emitters. Specifically, we target response in the UV-Vis-NIR and NIR-SWIR-MWIR via two material systems, InP (Eg=1.34 eV) and InSb (Eg=0.17 eV), respectively. Herein, we present results on InP and InSb nanowire array broadband absorbers, supported by experiment, simulation and analytic theory. Electromagnetic simulations indicate that, with directed optical design, tapered nanowire arrays and multi-radii nanowire arrays with 5% fill fraction can achieve greater than 95% broadband absorption (λInP=400-900nm, λInSb=1.5-5.5µm), due to efficient excitation and interband transition-mediated attenuation of the HE11 waveguide mode. Experimentally-fabricated InP nanowire arrays embedded in PDMS achieved broadband, polarization- and angle-insensitive 90-95% absorption, limited primarily by reflection off the PDMS interface. Addition of a thin, planar VO2 layer above a sparse InSb nanowire array enables active thermal tunability in the infrared, effecting a 50% modulation, from 87% (insulating VO2) to 43% (metallic VO2) average absorption. These concepts and results along with photovoltaic and other optical and optoelectronic device applications will be discussed.

VLBI2010 and the Westford Station - The Path Forward

NASA Astrophysics Data System (ADS)

Beaudoin, C.; Wilson, K.; Whittier, B.; Whitney, A.; McWhirter, R.; Smythe, J. SooHoo, D.; Ruszczyk, C.; Rogers, A.; Poirier, M.; Niell, A.; Corey, B.; Cappallo, R.; Byford, J.; Bolis, P.

2012-12-01

For the past three years the role of the Westford antenna in geodetic VLBI has been two-fold. Over this time its primary purpose has been to participate in standard S/X-band geodetic VLBI observations. In its secondary role the Westford antenna has been converted into a research instrument, facilitating the development of the broadband geodetic VLBI observing technique. As a research instrument, the Westford antenna incorporates a commercially-available ETS-Lindgren 3164 quadridge antenna as a radio telescope feed. The system also uses the VLBI2010 data acquisition system that incorporates digital backends (DBEs) implementing a polyphase filter bank processor. The process of converting the station from its mode of operations to a research instrument often introduces subtle anomalies that must be diagnosed prior to broadband observing. Furthermore, this bifurcation of the station's role is not in line with the goals of the VLBI2010 specifications. Until recently it has not been possible for the Westford station to serve as both an operational and research instrument without conversion for two reasons: poor sensitivity and incompatibility of backend baseband filter bandwidths. The poor sensitivity of the Westford antenna as a broadband radio telescope is in large part due to the commercial broadband feed which was readily available when the proof-of-concept VLBI2010 observations were initiated. However, with the materialization of the quadridge flared horn (QRFH) by the California Institute of Technology and with the improvements in the DiFX software correlator, the necessary components are now available to upgrade the Westford station to full-broadband capability while adhering to the mandate to maintain backwards compatibility with the legacy S/X systems. In this paper we will present the path forward for upgrading the Westford site to full-broadband capability while maintaining S/X compatibility.

Light extinction by Secondary Organic Aerosol: an intercomparison of three broadband cavity spectrometers

NASA Astrophysics Data System (ADS)

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

2013-07-01

Broadband optical cavity spectrometers are maturing as a technology for trace gas detection, but only recently have they been used to retrieve the extinction coefficient of aerosols. Sensitive broadband extinction measurements allow explicit separation of gas and particle phase spectral contributions, as well as continuous spectral measurements of aerosol extinction in favourable cases. In this work, we report an intercomparison study of the aerosol extinction coefficients measured by three such instruments: a broadband cavity ring-down spectrometer (BBCRDS), a cavity-enhanced differential optical absorption spectrometer (CE-DOAS), and an incoherent broadband cavity-enhanced absorption spectrometer (IBBCEAS). Experiments were carried out in the SAPHIR atmospheric simulation chamber as part of the NO3Comp campaign to compare the measurement capabilities of NO3 and N2O5 instrumentation. Aerosol extinction coefficients between 655 and 690 nm are reported for secondary organic aerosols (SOA) formed by the NO3 oxidation of β-pinene under dry and humid conditions. Despite different measurement approaches and spectral analysis procedures, the three instruments retrieved aerosol extinction coefficients that were in close agreement. The refractive index of SOA formed from the β-pinene + NO3 reaction was 1.61, and was not measurably affected by the chamber humidity or by aging of the aerosol over several hours. This refractive index is significantly larger than SOA refractive indices observed in other studies of OH and ozone-initiated terpene oxidations, and may be caused by the large proportion of organic nitrates in the particle phase. In an experiment involving ammonium sulphate particles the aerosol extinction coefficients as measured by IBBCEAS were found to be in reasonable agreement with those calculated using Mie theory. The results of the study demonstrate the potential of broadband cavity spectrometers for determining the optical properties of aerosols.

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

NASA Astrophysics Data System (ADS)

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

2013-11-01

Broadband optical cavity spectrometers are maturing as a technology for trace-gas detection, but only recently have they been used to retrieve the extinction coefficient of aerosols. Sensitive broadband extinction measurements allow explicit separation of gas and particle phase spectral contributions, as well as continuous spectral measurements of aerosol extinction in favourable cases. In this work, we report an intercomparison study of the aerosol extinction coefficients measured by three such instruments: a broadband cavity ring-down spectrometer (BBCRDS), a cavity-enhanced differential optical absorption spectrometer (CE-DOAS), and an incoherent broadband cavity-enhanced absorption spectrometer (IBBCEAS). Experiments were carried out in the SAPHIR atmospheric simulation chamber as part of the NO3Comp campaign to compare the measurement capabilities of NO3 and N2O5 instrumentation. Aerosol extinction coefficients between 655 and 690 nm are reported for secondary organic aerosols (SOA) formed by the NO3 oxidation of β-pinene under dry and humid conditions. Despite different measurement approaches and spectral analysis procedures, the three instruments retrieved aerosol extinction coefficients that were in close agreement. The refractive index of SOA formed from the β-pinene + NO3 reaction was 1.61, and was not measurably affected by the chamber humidity or by aging of the aerosol over several hours. This refractive index is significantly larger than SOA refractive indices observed in other studies of OH and ozone-initiated terpene oxidations, and may be caused by the large proportion of organic nitrates in the particle phase. In an experiment involving ammonium sulfate particles, the aerosol extinction coefficients as measured by IBBCEAS were found to be in reasonable agreement with those calculated using the Mie theory. The results of the study demonstrate the potential of broadband cavity spectrometers for determining the optical properties of aerosols.

Measuring Broadband IR Irradiance in the Direct Solar Beam and Recent Development

NASA Astrophysics Data System (ADS)

Reda, I.; Andreas, A.; Dooraghi, M.; Habte, A.; Sengupta, M.; Kutchenreiter, M.

2016-12-01

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

Bandwidth in bolometric interferometry

NASA Astrophysics Data System (ADS)

Charlassier, R.; Bunn, E. F.; Hamilton, J.-Ch.; Kaplan, J.; Malu, S.

2010-05-01

Context. Bolometric interferometry is a promising new technology with potential applications to the detection of B-mode polarization fluctuations of the cosmic microwave background (CMB). A bolometric interferometer will have to take advantage of the wide spectral detection band of its bolometers to be competitive with imaging experiments. A crucial concern is that interferometers are assumed to be significantly affected by a spoiling effect known as bandwidth smearing. Aims: We investigate how the bandwidth modifies the work principle of a bolometric interferometer and affects its sensitivity to the CMB angular power spectra. Methods: We obtain analytical expressions for the broadband visibilities measured by broadband heterodyne and bolometric interferometers. We investigate how the visibilities must be reconstructed in a broadband bolometric interferometer and show that this critically depends on hardware properties of the modulation phase shifters. If the phase shifters produce shifts that are constant with respect to frequency, the instrument works like its monochromatic version (the modulation matrix is not modified), while if they vary (linearly or otherwise) with respect to frequency, one has to perform a special reconstruction scheme, which allows the visibilities to be reconstructed in frequency subbands. Using an angular power spectrum estimator that accounts for the bandwidth, we finally calculate the sensitivity of a broadband bolometric interferometer. A numerical simulation is performed that confirms the analytical results. Results: We conclude that (i) broadband bolometric interferometers allow broadband visibilities to be reconstructed regardless of the type of phase shifters used and (ii) for dedicated B-mode bolometric interferometers, the sensitivity loss caused by bandwidth smearing is quite acceptable, even for wideband instruments (a factor of 2 loss for a typical 20% bandwidth experiment).

Improving land surface emissivty parameter for land surface models using portable FTIR and remote sensing observation in Taklimakan Desert

NASA Astrophysics Data System (ADS)

Liu, Yongqiang; Mamtimin, Ali; He, Qing

2014-05-01

Because land surface emissivity (ɛ) has not been reliably measured, global climate model (GCM) land surface schemes conventionally set this parameter as simply assumption, for example, 1 as in the National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Prediction (NCEP) model, 0.96 for soil and wetland in the Global and Regional Assimilation and Prediction System (GRAPES) Common Land Model (CoLM). This is the so-called emissivity assumption. Accurate broadband emissivity data are needed as model inputs to better simulate the land surface climate. It is demonstrated in this paper that the assumption of the emissivity induces errors in modeling the surface energy budget over Taklimakan Desert where ɛ is far smaller than original value. One feasible solution to this problem is to apply the accurate broadband emissivity into land surface models. The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument has routinely measured spectral emissivities in six thermal infrared bands. The empirical regression equations have been developed in this study to convert these spectral emissivities to broadband emissivity required by land surface models. In order to calibrate the regression equations, using a portable Fourier Transform infrared (FTIR) spectrometer instrument, crossing Taklimakan Desert along with highway from north to south, to measure the accurate broadband emissivity. The observed emissivity data show broadband ɛ around 0.89-0.92. To examine the impact of improved ɛ to radiative energy redistribution, simulation studies were conducted using offline CoLM. The results illustrate that large impacts of surface ɛ occur over desert, with changes up in surface skin temperature, as well as evident changes in sensible heat fluxes. Keywords: Taklimakan Desert, surface broadband emissivity, Fourier Transform infrared spectrometer, MODIS, CoLM

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

NASA Astrophysics Data System (ADS)

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

2016-03-01

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

Validation of Improved Broadband Shortwave and Longwave Fluxes Derived From GOES

NASA Technical Reports Server (NTRS)

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

2009-01-01

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

47 CFR 27.1218 - Designated entities.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 2 2011-10-01 2011-10-01 false Designated entities. 27.1218 Section 27.1218... COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27.1218 Designated entities. (a) Eligibility for small business provisions. (1) A small business is an entity that, together with...

GPS Spectrum Management (Briefing Charts)

DTIC Science & Technology

2015-04-29

15) agenda item (AI) 1.1 draft conference preparatory meeting ( CPM ); proactively keeping possible mobile broadband allocations away from GPS in-band...UNCLASSIFIED/APPROVED FOR PUBLIC RELEASE ITU Watch Items SPACE AND MISSILE SYSTEMS CENTER • WRC-15 AI 1.1 -mobile broadband; finalization of CPM in Mar

K/Ka-band Antenna for Broadband Aeronautical Mobile Application

NASA Technical Reports Server (NTRS)

Densmore, A.

1994-01-01

The Jet Propulsion Laboratory (JPL) has recently begun the development of a Broadband Aeronauical Terminal (BAT) for duplex video satellite communications on commercial or business class aircraft. The BAT is designed for use with NASA's K/Ka-band Advanced Communications Technology Satellite (ACTS).

77 FR 63757 - Extension of the Commission's Rules Regarding Outage Reporting to Interconnected Voice Over...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-10-17

... Commission's Rules Regarding Outage Reporting to Interconnected Voice Over Internet Protocol Service Providers and Broadband Internet Service Providers AGENCY: Federal Communications Commission. ACTION: Final... Regarding Outage Reporting to Interconnected Voice Over Internet Protocol Service Providers and Broadband...

Community Wireless Networks

ERIC Educational Resources Information Center

Feld, Harold

2005-01-01

With increasing frequency, communities are seeing the arrival of a new class of noncommercial broadband providers: community wireless networks (CWNs). Utilizing the same wireless technologies that many colleges and universities have used to create wireless networks on campus, CWNs are creating broadband access for free or at costs well below…

75 FR 15668 - Information Collection Activity; Comment Request

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-30

...., STOP 1522, Room 5159, South Building, Washington, DC 20250-1522. Telephone: (202) 690-1078. Fax: (202...., Washington, DC 20250-1522. Fax: (202) 720-8435. Title: Broadband Grant Program. OMB Control Number: 0572-0127...'' basis. The ``community-oriented connectivity'' concept integrates the deployment of broadband...

Broadband electromagnetic dipole scattering by coupled multiple nanospheres

NASA Astrophysics Data System (ADS)

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.

A broadband high-transmission gradient phase discontinuity metasurface

NASA Astrophysics Data System (ADS)

Liu, Yahong; Liu, Congcong; Song, Kun; Li, Meize; Zhao, Xiaopeng

2018-03-01

Metasurfaces have attracted significant attention due to the control of the electromagnetic waves that they enable. In this paper, we demonstrate a high-transmission gradient phase discontinuity metasurface composed of metallic rods and cylindrical dielectric resonators operating at a broadband microwave frequency from 8 GHz to 9.8 GHz, with a fractional bandwidth of 20.2%. The proposed gradient phase discontinuity metasurface can achieve complete 2π transmission phase coverage with π/4 phase intervals by varying the geometric parameters of the dielectric resonators and metallic rods. It is shown that the proposed metasurface can refract a normally incident plane wave to an angle of 30°. The broadband metasurface is flexible, and the refracted angle can be adjusted easily by varying the lattice constant. Besides the broadband anomalous refraction, we also demonstrate the metasurface can produce an interesting vortex and wave-focusing in the wide frequency range from 8 GHz to 9.8 GHz. Finally, we demonstrate that the present metasurface can tailor interference wavefronts to plane wavefronts.

Impact of Azimuthally Controlled Fluidic Chevrons on Jet Noise

NASA Technical Reports Server (NTRS)

Henderson, Brenda S.; Norum, Thomas D.

2008-01-01

The impact of azimuthally controlled air injection on broadband shock noise and mixing noise for single and dual stream jets was investigated. The single stream experiments focused on noise reduction for low supersonic jet exhausts. Dual stream experiments included high subsonic core and fan conditions and supersonic fan conditions with transonic core conditions. For the dual stream experiments, air was injected into the core stream. Significant reductions in broadband shock noise were achieved in a single jet with an injection mass flow equal to 1.2% of the core mass flow. Injection near the pylon produced greater broadband shock noise reductions than injection at other locations around the nozzle periphery. Air injection into the core stream did not result in broadband shock noise reduction in dual stream jets. Fluidic injection resulted in some mixing noise reductions for both the single and dual stream jets. For subsonic fan and core conditions, the lowest noise levels were obtained when injecting on the side of the nozzle closest to the microphone axis.

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

USGS Publications Warehouse

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.

Estimation of some transducer parameters in a broadband piezoelectric transmitter by using an artificial intelligence technique.

PubMed

Ruíz, A; Ramos, A; San Emeterio, J L

2004-04-01

An estimation procedure to efficiently find approximate values of internal parameters in ultrasonic transducers intended for broadband operation would be a valuable tool to discover internal construction data. This information is necessary in the modelling and simulation of acoustic and electrical behaviour related to ultrasonic systems containing commercial transducers. There is not a general solution for this generic problem of parameter estimation in the case of broadband piezoelectric probes. In this paper, this general problem is briefly analysed for broadband conditions. The viability of application in this field of an artificial intelligence technique supported on the modelling of the transducer internal components is studied. A genetic algorithm (GA) procedure is presented and applied to the estimation of different parameters, related to two transducers which are working as pulsed transmitters. The efficiency of this GA technique is studied, considering the influence of the number and variation range of the estimated parameters. Estimation results are experimentally ratified.

Broadband and wide-angle RCS reduction using a 2-bit coding ultrathin metasurface at terahertz frequencies

PubMed Central

Liang, Lanju; Wei, Minggui; Yan, Xin; Wei, Dequan; Liang, Dachuan; Han, Jiaguang; Ding, Xin; Zhang, GaoYa; Yao, Jianquan

2016-01-01

A novel broadband and wide-angle 2-bit coding metasurface for radar cross section (RCS) reduction is proposed and characterized at terahertz (THz) frequencies. The ultrathin metasurface is composed of four digital elements based on a metallic double cross line structure. The reflection phase difference of neighboring elements is approximately 90° over a broadband THz frequency. The mechanism of RCS reduction is achieved by optimizing the coding element sequences, which redirects the electromagnetic energies to all directions in broad frequencies. An RCS reduction of less than −10 dB bandwidth from 0.7 THz to 1.3 THz is achieved in the experimental and numerical simulations. The simulation results also show that broadband RCS reduction can be achieved at an incident angle below 60° for TE and TM polarizations under flat and curve coding metasurfaces. These results open a new approach to flexibly control THz waves and may offer widespread applications for novel THz devices. PMID:27982089

Systematic errors in the determination of the spectroscopic g-factor in broadband ferromagnetic resonance spectroscopy: A proposed solution

NASA Astrophysics Data System (ADS)

Gonzalez-Fuentes, C.; Dumas, R. K.; García, C.

2018-01-01

A theoretical and experimental study of the influence of small offsets of the magnetic field (δH) on the measurement accuracy of the spectroscopic g-factor (g) and saturation magnetization (Ms) obtained by broadband ferromagnetic resonance (FMR) measurements is presented. The random nature of δH generates systematic and opposite sign deviations of the values of g and Ms with respect to their true values. A δH on the order of a few Oe leads to a ˜10% error of g and Ms for a typical range of frequencies employed in broadband FMR experiments. We propose a simple experimental methodology to significantly minimize the effect of δH on the fitted values of g and Ms, eliminating their apparent dependence in the range of frequencies employed. Our method was successfully tested using broadband FMR measurements on a 5 nm thick Ni80Fe20 film for frequencies ranging between 3 and 17 GHz.

Broadband and wide-angle RCS reduction using a 2-bit coding ultrathin metasurface at terahertz frequencies.

PubMed

Liang, Lanju; Wei, Minggui; Yan, Xin; Wei, Dequan; Liang, Dachuan; Han, Jiaguang; Ding, Xin; Zhang, GaoYa; Yao, Jianquan

2016-12-16

A novel broadband and wide-angle 2-bit coding metasurface for radar cross section (RCS) reduction is proposed and characterized at terahertz (THz) frequencies. The ultrathin metasurface is composed of four digital elements based on a metallic double cross line structure. The reflection phase difference of neighboring elements is approximately 90° over a broadband THz frequency. The mechanism of RCS reduction is achieved by optimizing the coding element sequences, which redirects the electromagnetic energies to all directions in broad frequencies. An RCS reduction of less than -10 dB bandwidth from 0.7 THz to 1.3 THz is achieved in the experimental and numerical simulations. The simulation results also show that broadband RCS reduction can be achieved at an incident angle below 60° for TE and TM polarizations under flat and curve coding metasurfaces. These results open a new approach to flexibly control THz waves and may offer widespread applications for novel THz devices.

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

NASA Astrophysics Data System (ADS)

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.

Growth of quantum three-dimensional structure of InGaAs emitting at 1 μm applicable for a broadband near-infrared light source

NASA Astrophysics Data System (ADS)

Ozaki, Nobuhiko; Kanehira, Shingo; Hayashi, Yuma; Ohkouchi, Shunsuke; Ikeda, Naoki; Sugimoto, Yoshimasa; Hogg, Richard A.

2017-11-01

We obtained a high-intensity and broadband emission centered at 1 μm from InGaAs quantum three-dimensional (3D) structures grown on a GaAs substrate using molecular beam epitaxy. An InGaAs thin layer grown on GaAs with a thickness close to the critical layer thickness is normally affected by strain as a result of the lattice mismatch and introduced misfit dislocations. However, under certain growth conditions for the In concentration and growth temperature, the growth mode of the InGaAs layer can be transformed from two-dimensional to 3D growth. We found the optimal conditions to obtain a broadband emission from 3D structures with a high intensity and controlled center wavelength at 1 μm. This method offers an alternative approach for fabricating a broadband near-infrared light source for telecommunication and medical imaging systems such as for optical coherence tomography.

Ultra-broadband and efficient surface plasmon polariton launching through metallic nanoslits of subwavelength period

PubMed Central

Li, Guangyuan; Zhang, Jiasen

2014-01-01

Ultra-broadband, efficient and unidirectional surface plasmon polariton (SPP) launching is of great concern in plasmonic devices and circuits. To address this challenge, a novel method adopting deep-subwavelength slits of subwavelength period (λSPP/4 ~ λSPP/3) in a thick metal film and under backside illumination is proposed. A new band pattern featuring broadband and wide angular characteristics, which is due to the coupling of the zeroth-order SPP resonance at the superstrate–metal interface and the first-order SPP resonance at the metal–substrate interface, is observed for the first time in the dispersion diagram. Unidirectional SPP launching efficiency of ~50%, ultra-broad bandwidth of up to 780 nm, covering the entire optical fiber communication bands, and relatively wide angular range of 7° are achieved. This remarkable efficient, ultra-broadband and wide angular performance is demonstrated by carefully designed experiments in the near infrared regime, showing good agreement with numerical results. PMID:25081812

Ultra-broadband and efficient surface plasmon polariton launching through metallic nanoslits of subwavelength period.

PubMed

Li, Guangyuan; Zhang, Jiasen

2014-08-01

Ultra-broadband, efficient and unidirectional surface plasmon polariton (SPP) launching is of great concern in plasmonic devices and circuits. To address this challenge, a novel method adopting deep-subwavelength slits of subwavelength period (λSPP/4 ~ λSPP/3) in a thick metal film and under backside illumination is proposed. A new band pattern featuring broadband and wide angular characteristics, which is due to the coupling of the zeroth-order SPP resonance at the superstrate-metal interface and the first-order SPP resonance at the metal-substrate interface, is observed for the first time in the dispersion diagram. Unidirectional SPP launching efficiency of ~50%, ultra-broad bandwidth of up to 780 nm, covering the entire optical fiber communication bands, and relatively wide angular range of 7° are achieved. This remarkable efficient, ultra-broadband and wide angular performance is demonstrated by carefully designed experiments in the near infrared regime, showing good agreement with numerical results.

Broadband impedance boundary conditions for the simulation of sound propagation in the time domain.

PubMed

Bin, Jonghoon; Yousuff Hussaini, M; Lee, Soogab

2009-02-01

An accurate and practical surface impedance boundary condition in the time domain has been developed for application to broadband-frequency simulation in aeroacoustic problems. To show the capability of this method, two kinds of numerical simulations are performed and compared with the analytical/experimental results: one is acoustic wave reflection by a monopole source over an impedance surface and the other is acoustic wave propagation in a duct with a finite impedance wall. Both single-frequency and broadband-frequency simulations are performed within the framework of linearized Euler equations. A high-order dispersion-relation-preserving finite-difference method and a low-dissipation, low-dispersion Runge-Kutta method are used for spatial discretization and time integration, respectively. The results show excellent agreement with the analytical/experimental results at various frequencies. The method accurately predicts both the amplitude and the phase of acoustic pressure and ensures the well-posedness of the broadband time-domain impedance boundary condition.

Magnetization pinning in conducting films demonstrated using broadband ferromagnetic resonance

NASA Astrophysics Data System (ADS)

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.

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

NASA Technical Reports Server (NTRS)

Loyd, B.; Harris, W. L.

1995-01-01

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

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

PubMed

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.

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

PubMed

D'Angelo, Francesco; Mics, Zoltán; Bonn, Mischa; Turchinovich, Dmitry

2014-05-19

Terahertz-range dielectric properties of the common polymers low-density polyethylene (LDPE), cyclic olefin/ethylene copolymer (TOPAS®), polyamide-6 (PA6), and polytetrafluoroethylene (PTFE or Teflon®) are characterized in the ultra-broadband frequency window 2-15 THz, using a THz time-domain spectrometer employing air-photonics for the generation and detection of single-cycle sub-50 fs THz transients. The time domain measurements provide direct access to both the absorption and refractive index spectra. The polymers LDPE and TOPAS® demonstrate negligible absorption and spectrally-flat refractive index across the entire spectroscopy window, revealing the high potential of these polymers for applications in THz photonics such as ultra-broadband polymer-based dielectric mirrors, waveguides, and fibers. Resonant high-frequency polar vibrational modes are observed and assigned in polymers PA6 and PTFE, and their dielectric functions in the complete frequency window 2-15 THz are theoretically reproduced. Our results demonstrate the potential of ultra-broadband air-photonics-based THz time domain spectroscopy as a valuable analytic tool for materials science.

Cable-telco architectures

NASA Astrophysics Data System (ADS)

McGrath, Carl J.

1994-11-01

Continued evolution of consumer broadband services such as digital video and digital multimedia has placed renewed emphasis on the need for network solutions to the broadband connectivity challenge. Although still important to architectural planners, connection oriented broadband services based on ISDN concepts must now compete with a wider array of broadcast and highly asymmetrical services for bandwidth on the network. For network operators, the business imperative is to identify and execute a network rebuild plan that will meet the capacity and flexibility needs of these services and compete with the inevitable alternate paths into the home. This paper focuses on some of the key issues facing broadband network planners as they search for the best architecture to meet the business and operations goals in their segment of the market. It will be apparent that no single optimum solution exists for all deployment scenarios, emphasizing the need for flexible and modular sources (such as servers) and network interfaces (such as set tops) which preserve the value of content, the ultimate driver in this round of network revolution.

Traffic handling capability of a broadband indoor wireless network using CDMA multiple access

NASA Astrophysics Data System (ADS)

Zhang, Chang G.; Hafez, H. M.; Falconer, David D.

1994-05-01

CDMA (code division multiple access) may be an attractive technique for wireless access to broadband services because of its multiple access simplicity and other appealing features. In order to investigate traffic handling capabilities of a future network providing a variety of integrated services, this paper presents a study of a broadband indoor wireless network supporting high-speed traffic using CDMA multiple access. The results are obtained through the simulation of an indoor environment and the traffic capabilities of the wireless access to broadband 155.5 MHz ATM-SONET networks using the mm-wave band. A distributed system architecture is employed and the system performance is measured in terms of call blocking probability and dropping probability. The impacts of the base station density, traffic load, average holding time, and variable traffic sources on the system performance are examined. The improvement of system performance by implementing various techniques such as handoff, admission control, power control and sectorization are also investigated.

A broadband LED source in visible to short-wave-infrared wavelengths for spectral tumor diagnostics

NASA Astrophysics Data System (ADS)

Hayashi, Daiyu; van Dongen, Anne Marie; Boerekamp, Jack; Spoor, Sandra; Lucassen, Gerald; Schleipen, Jean

2017-06-01

Various tumor types exhibit the spectral fingerprints in the absorption and reflection spectra in visible and especially in near- to short-wave-infrared wavelength ranges. For the purpose of spectral tumor diagnostics by means of diffuse reflectance spectroscopy, we developed a broadband light emitting diode (LED) source consisting of a blue LED for optical excitation, Lu3Al5O12:Ce3+,Cr3+ luminescent garnet for visible to near infrared emissions, and Bismuth doped GeO2 luminescent glass for near-infrared to short-wave infrared emissions. It emits broad-band light emissions continuously in 470-1600 nm with a spectral gap at 900-1000 nm. In comparison to the currently available broadband light sources like halogen lamps, high-pressure discharge lamps and super continuum lasers, the light sources of this paper has significant advantages for spectral tissue diagnostics in high-spectral stability, improved light coupling to optical fibers, potential in low light source cost and enabling battery-drive.

On Theoretical Broadband Shock-Associated Noise Near-Field Cross-Spectra

NASA Technical Reports Server (NTRS)

Miller, Steven A. E.

2015-01-01

The cross-spectral acoustic analogy is used to predict auto-spectra and cross-spectra of broadband shock-associated noise in the near-field and far-field from a range of heated and unheated supersonic off-design jets. A single equivalent source model is proposed for the near-field, mid-field, and far-field terms, that contains flow-field statistics of the shock wave shear layer interactions. Flow-field statistics are modeled based upon experimental observation and computational fluid dynamics solutions. An axisymmetric assumption is used to reduce the model to a closed-form equation involving a double summation over the equivalent source at each shock wave shear layer interaction. Predictions are compared with a wide variety of measurements at numerous jet Mach numbers and temperature ratios from multiple facilities. Auto-spectral predictions of broadband shock-associated noise in the near-field and far-field capture trends observed in measurement and other prediction theories. Predictions of spatial coherence of broadband shock-associated noise accurately capture the peak coherent intensity, frequency, and spectral width.

Broadband moth-eye antireflection coatings on silicon

NASA Astrophysics Data System (ADS)

Sun, Chih-Hung; Jiang, Peng; Jiang, Bin

2008-02-01

We report a bioinspired templating technique for fabricating broadband antireflection coatings that mimic antireflective moth eyes. Wafer-scale, subwavelength-structured nipple arrays are directly patterned on silicon using spin-coated silica colloidal monolayers as etching masks. The templated gratings exhibit excellent broadband antireflection properties and the normal-incidence specular reflection matches with the theoretical prediction using a rigorous coupled-wave analysis (RCWA) model. We further demonstrate that two common simulation methods, RCWA and thin-film multilayer models, generate almost identical prediction for the templated nipple arrays. This simple bottom-up technique is compatible with standard microfabrication, promising for reducing the manufacturing cost of crystalline silicon solar cells.

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

NASA Astrophysics Data System (ADS)

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 electrical impedance matching for piezoelectric ultrasound transducers.

PubMed

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.

Broadband sound blocking in phononic crystals with rotationally symmetric inclusions.

PubMed

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

2015-09-01

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

Preparation and performance of broadband antireflective sub-wavelength structures on Ge substrate

NASA Astrophysics Data System (ADS)

Shen, Xiang-Wei; Liu, Zheng-Tang; Li, Yang-Ping; Lu, Hong-Cheng; Xu, Qi-Yuan; Liu, Wen-Ting

2009-01-01

Sub-wavelength structures (SWS) were prepared on Ge substrates through photolithography and reactive ion etching (RIE) technology for broadband antireflective purposes in the long wave infrared (LWIR) waveband of 8-12 μm. Topography of the etched patterns was observed using high resolution optical microscope and atomic force microscope (AFM). Infrared transmission performance of the SWS was investigated by Fourier transform infrared (FTIR) spectrometer. Results show that the etched patterns were of high uniformity and fidelity, the SWS exhibited a good broadband antireflective performance with the increment of the average transmittance which is over 8-12 μm up to 8%.

Broadband stimulated Raman spectroscopy in the deep ultraviolet region

NASA Astrophysics Data System (ADS)

Kuramochi, Hikaru; Fujisawa, Tomotsumi; Takeuchi, Satoshi; Tahara, Tahei

2017-09-01

We report broadband stimulated Raman measurements in the deep ultraviolet (DUV) region, which enables selective probing of the aromatic amino acid residues inside proteins through the resonance enhancement. We combine the narrowband DUV Raman pump pulse (<10 cm-1) at wavelengths as short as 240 nm and the broadband DUV probe pulse (>1000 cm-1) to realize stimulated Raman measurements covering a >1500 cm-1 spectral window. The stimulated Raman measurements for neat solvents, tryptophan, tyrosine, and glucose oxidase are performed using 240- and 290-nm Raman pump, highlighting the high potential of the DUV stimulated Raman probe for femtosecond time-resolved study of proteins.

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

NASA Astrophysics Data System (ADS)

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

2017-11-01

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

Broadband pulsed flow using piezoelectric microjets

NASA Astrophysics Data System (ADS)

Hogue, Joshua; Solomon, John; Hays, Michael; Alvi, Farrukh; Oates, William

2010-04-01

A piezohydraulic microjet design and experimental results are presented to demonstrate broadband active flow control for applications on various aircraft structures including impinging jets, rotor blades, cavity bays, etc. The microjet actuator includes a piezoelectric stack actuator and hydraulic circuit that is used to throttle a 400 μm diameter microjet using hydraulic amplification of the piezoelectric stack actuator. This system is shown to provide broadband pulsed flow actuation up to 800 Hz. Unsteady pressure measurements of the microjet's exit flow are coupled with high-speed phase imagery using micro-Schlieren techniques to quantify the flow field. These results are compared with in situ stack actuator displacements using strain gauge measurements.

Investigation of broadband terahertz generation from metasurface

NASA Astrophysics Data System (ADS)

Fang, Ming; Niu, Kaikun; Huang, Zhiaxiang; Sha, Wei E. I.; Wu, Xianliang; Koschny, Thomas; Soukoulis, Costas M.

2018-05-01

The nonlinear metamaterials have been shown to provide nonlinear properties with high nonlinear conversion efficiency and in a myriad of light manipulation. Here we study terahertz generation from nonlinear metasurface consisting of single layer nanoscale split-ring resonator array. The terahertz generation due to optical rectification by the second-order nonlinearity of the split-ring resonator is investigated by a time-domain implementation of the hydrodynamic model for electron dynamics in metal. The results show that the nonlinear metasurface enables us to generate broadband terahertz radiation and free from quasi-phase-matching conditions. The proposed scheme provides a new concept of broadband THz source and designing nonlinear plasmonic metamaterials.

Broadband spectral shaping in regenerative amplifier based on modified polarization-encoded chirped pulse amplification

NASA Astrophysics Data System (ADS)

Wang, Xinliang; Lu, Xiaoming; Liu, Yanqi; Xu, Yi; Wang, Cheng; Li, Shuai; Yu, Linpeng; Liu, Xingyan; Liu, Keyang; Xu, Rongjie; Leng, Yuxin

2018-06-01

We present an intra-cavity spectral shaping method to suppress the spectral narrowing in a Ti:sapphire (Ti:Sa) regenerative amplifier. The spectral shaping is realized by manipulating the stored energies of two Ti:Sa crystals with orthogonal c-axes, changing the length of a quartz plate, and rotating a broadband achromatic half-wave plate. Using this method, in our proof-of-concept experiment, an 84-nm-(FWHM)-broadband amplified pulse with an energy gain larger than 106 is obtained, which supports a 17.8 fs Fourier-transform-limited pulse duration. The pulse is compressed to 18.9 fs.

Underwater noise of small personal watercraft (jet skis).

PubMed

Erbe, Christine

2013-04-01

Personal watercraft (water scooters, jet skis) were recorded under water in Bramble Bay, Queensland, Australia. Underwater noise emissions consisted of broadband energy between 100 Hz and 10 kHz due to the vibrating bubble cloud generated by the jet stream, overlain with frequency-modulated tonals corresponding to impeller blade rates and harmonics. Broadband monopole source levels were 149, 137, and 122 dB re 1 μPa @ 1 m (5th, 50th, and 95th percentiles). Even though these are lower than those of small propeller-driven boats, it is not necessarily the broadband source level that correlates with the bioacoustic impact on marine fauna.

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

NASA Astrophysics Data System (ADS)

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.

Broadband impedance calculations and single bunch instabilities estimations of of the HLS-II storage ring

NASA Astrophysics Data System (ADS)

Zhang, Qing-Kun; Wang, Lin; Li, Wei-Min; Gao, Wei-Wei

2015-12-01

The upgrade project of the Hefei Light Source storage ring is under way. In this paper, the broadband impedances of resistive wall and coated ceramic vacuum chamber are calculated using the analytic formula, and the wake fields and impedances of other designed vacuum chambers are simulated by CST code, and then a broadband impedance model is obtained. Using the theoretical formula, longitudinal and transverse single bunch instabilities are discussed. With the carefully-designed vacuum chamber, we find that the thresholds of the beam instabilities are higher than the beam current goal. Supported by Natural Science Foundation of China (11175182, 11175180)

Single-shot time stretch stimulated Raman spectroscopy (Conference Presentation)

NASA Astrophysics Data System (ADS)

Saltarelli, Francesco; Kumar, Vikas; Viola, Daniele; Crisafi, Francesco; Preda, Fabrizio; Cerullo, Giulio; Polli, Dario

2017-02-01

Stimulated Raman scattering spectroscopy is a powerful technique for label-free molecular identification, but its broadband implementation is technically challenging. We introduce and experimentally demonstrate a novel approach based on photonic time stretch. The broadband femtosecond Stokes pulse, after interacting with the sample, is stretched by a telecom fiber to 15ns, mapping its spectrum in time. The signal is sampled through a fast analog-to-digital converter, providing single-shot spectra at 80-kHz rate. We demonstrate 10^-5 sensitivity over 500 cm-1 in the C-H region. Our results pave the way to high-speed broadband vibrational imaging for materials science and biophotonics.

Spectral modification of the laser emission of a terahertz quantum cascade laser induced by broad-band double pulse injection seeding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Markmann, Sergej, E-mail: sergej.markmann@ruhr-uni-bochum.de; Nong, Hanond, E-mail: nong.hanond@ruhr-uni-bochum.de; Hekmat, Negar

2015-09-14

We demonstrate by injection seeding that the spectral emission of a terahertz (THz) quantum cascade laser (QCL) can be modified with broad-band THz pulses whose bandwidths are greater than the QCL bandwidth. Two broad-band THz pulses delayed in time imprint a modulation on the single THz pulse spectrum. The resulting spectrum is used to injection seed the THz QCL. By varying the time delay between the THz pulses, the amplitude distribution of the QCL longitudinal modes is modified. By applying this approach, the QCL emission is reversibly switched from multi-mode to single mode emission.

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

NASA Astrophysics Data System (ADS)

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

2016-11-01

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

Bragg-Berry mirrors: reflective broadband q-plates.

PubMed

Rafayelyan, Mushegh; Brasselet, Etienne

2016-09-01

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

Investigation of broadband terahertz generation from metasurface.

PubMed

Fang, Ming; Niu, Kaikun; Huang, Zhiaxiang; Sha, Wei E I; Wu, Xianliang; Koschny, Thomas; Soukoulis, Costas M

2018-05-28

The nonlinear metamaterials have been shown to provide nonlinear properties with high nonlinear conversion efficiency and in a myriad of light manipulation. Here we study terahertz generation from nonlinear metasurface consisting of single layer nanoscale split-ring resonator array. The terahertz generation due to optical rectification by the second-order nonlinearity of the split-ring resonator is investigated by a time-domain implementation of the hydrodynamic model for electron dynamics in metal. The results show that the nonlinear metasurface enables us to generate broadband terahertz radiation and free from quasi-phase-matching conditions. The proposed scheme provides a new concept of broadband THz source and designing nonlinear plasmonic metamaterials.

Broadband chirality and asymmetric transmission in ultrathin 90°-twisted Babinet-inverted metasurfaces

NASA Astrophysics Data System (ADS)

Shi, J. H.; Ma, H. F.; Guan, C. Y.; Wang, Z. P.; Cui, T. J.

2014-04-01

A broadband asymmetric transmission of linearly polarized waves with totally suppressed copolarization transmission is experimentally demonstrated in ultrathin 90°-twisted Babinet-inverted metasurfaces constructed by an array of asymmetrically split ring apertures. The only accessible direction-dependent cross-polarization transmission is allowed in this anisotropic chiral metamaterial. Through full-wave simulation and experiment results, the bilayered Babinet-inverted metasurface reveals broadband artificial chirality and asymmetric transmission, with a transmission contrast that is better than 17.7 dB within a 50% relative bandwidth for two opposite directions. In particular, we can modify polarization conversion efficiency and the bandwidth of asymmetric transmission via parametric study.

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

PubMed Central

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

76 FR 41497 - Privacy Act System of Records

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-14

...Pursuant to subsection (e)(4) of the Privacy Act of 1974, as amended (Privacy Act), 5 U.S.C. 552a, the FCC proposes to alter one system of records, FCC/OSP-1, ``Broadband Dead Zone Report and Consumer Broadband Test.'' The altered system of records incorporates more details about the voluntary fixed and mobile consumer broadband test. The FCC will also alter the categories of individuals; categories of records; the purposes for which the information is maintained; the retrievability procedures; Routine Use (5); and delete Routine Use (2); and make other edits and revisions as necessary to update the information and to comply with the requirements of the Privacy Act.

Ultra-Broadband Infrared Pulses from a Potassium-Titanyl Phosphate Optical Parametric Amplifier for VIS-IR-SFG Spectroscopy

NASA Astrophysics Data System (ADS)

Isaienko, Oleksandr; Borguet, Eric

A non-collinear KTP-OPA to provide ultra-broadband mid-infrared pulses was designed and characterized. With proper pulse-front and phase correction, the system has a potential for high-time resolution vibrational VIS-IR-SFG spectroscopy.

Employing broadband spectra and cluster analysis to assess thermal defoliation of cotton

USDA-ARS?s Scientific Manuscript database

Growers and field scouts need assistance in surveying cotton (Gossypium hirsutum L.) fields subjected to thermal defoliation to reap the benefits provided by this nonchemical defoliation method. A study was conducted to evaluate broadband spectral data and unsupervised classification as tools for s...

Thyroid tissue constituents characterization and application to in vivo studies by broadband (600-1200 nm) diffuse optical spectroscopy

NASA Astrophysics Data System (ADS)

Konugolu Venkata Sekar, Sanathana; Farina, Andrea; dalla Mora, Alberto; Taroni, Paola; Lindner, Claus; Mora, Mireia; Farzam, Parisa; Pagliazzi, Marco; Squarcia, Mattia; Halperin, Irene; Hanzu, Felicia A.; Dehghani, Hamid; Durduran, Turgut; Pifferi, Antonio

2017-07-01

We present the first broadband (600-1100 nm) diffuse optical characterization of thyroglobulin and tyrosine, which are thyroid-specific tissue constituents. In-vivo measurements at the thyroid region enabled their quantification for functional and diagnostic applications.

75 FR 45087 - Submission for OMB Review; Comment Request

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-02

... provide financial assistance to eligible entities that are proposing to deploy broadband transmission... assumptions used; (c) ways to enhance the quality, utility and clarity of the information to be collected; (d... Utilities Service Title: Broadband Grant Program. OMB Control Number: 0572-0127. Summary of Collection...

How To: Be VoIP-Savvy

ERIC Educational Resources Information Center

Branzburg, Jeffrey

2005-01-01

Cablevision, Comcast, Verizon, and many other high-speed broadband Internet providers are now also offering telephone services through "Voice over Internet Protocol" (VoIP). This technology sends ordinary telephone calls over the Internet rather than over telephone lines. While impractical without the use of a broadband Internet connection, with…

47 CFR 8.5 - No blocking.

Code of Federal Regulations, 2013 CFR

2013-10-01

... FEDERAL COMMUNICATIONS COMMISSION GENERAL PRESERVING THE OPEN INTERNET § 8.5 No blocking. (a) A person engaged in the provision of fixed broadband Internet access service, insofar as such person is so engaged... network management. (b) A person engaged in the provision of mobile broadband Internet access service...

47 CFR 8.5 - No blocking.

Code of Federal Regulations, 2012 CFR

2012-10-01

... FEDERAL COMMUNICATIONS COMMISSION GENERAL PRESERVING THE OPEN INTERNET § 8.5 No blocking. (a) A person engaged in the provision of fixed broadband Internet access service, insofar as such person is so engaged... network management. (b) A person engaged in the provision of mobile broadband Internet access service...

47 CFR 8.5 - No blocking.

Code of Federal Regulations, 2014 CFR

2014-10-01

... FEDERAL COMMUNICATIONS COMMISSION GENERAL PRESERVING THE OPEN INTERNET § 8.5 No blocking. (a) A person engaged in the provision of fixed broadband Internet access service, insofar as such person is so engaged... network management. (b) A person engaged in the provision of mobile broadband Internet access service...

Issues in the Adoption of Broadband-Enabled Learning

ERIC Educational Resources Information Center

Murphy, Elizabeth

2005-01-01

This paper presents one case of broadband-enabled learning (BEL) involving geo-culturally and organisationally diverse collaboration using music as the vehicle. Findings from five evaluations over a 15-month period were considered in relation to issues of relative advantage, compatibility, complexity, trialability, and observability. Advantages…

47 CFR 8.5 - No Blocking.

Code of Federal Regulations, 2011 CFR

2011-10-01

... FEDERAL COMMUNICATIONS COMMISSION GENERAL PRESERVING THE OPEN INTERNET § 8.5 No Blocking. (a) A person engaged in the provision of fixed broadband Internet access service, insofar as such person is so engaged... network management. (b) A person engaged in the provision of mobile broadband Internet access service...

Developing Strategies for Affordable Bandwidth.

ERIC Educational Resources Information Center

Educause Quarterly, 2000

2000-01-01

Written by Educause's Net@EDU Broadband Pricing Working Group, this article discusses what institutions of higher education can do to develop good partnerships with broadband vendors in order to negotiate affordable pricing for increased bandwidth. Describes problems with the marketplace, examples from a few universities, and points to remember…

Applying broadband spectra to assess biological control of saltcedar in West Texas

USDA-ARS?s Scientific Manuscript database

In Texas, natural resource managers, government officials, and scientists need effective means for monitoring biological control of saltcedar (Tamarix spp.) with the saltcedar leaf beetle (Diorhadba spp.). This study was conducted to evaluate broadband spectra within visible, red-edge, and near-inf...

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

USGS Publications Warehouse

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

2017-01-01

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

Broadband Noise Reduction of a Low-Speed Fan Noise Using Trailing Edge Blowing

NASA Technical Reports Server (NTRS)

Sutliff, Daniel L.

2005-01-01

An experimental proof-of-concept test was conducted to demonstrate reduction of rotor-stator interaction noise through the use of rotor-trailing edge blowing. The velocity deficit from the viscous wake of the rotor blades was reduced by injecting air into the wake from a continuous trailing edge slot. Hollow blades with interior guide vanes create flow channels through which externally supplied air flows from the blade root to the trailing edge. A previous paper documented the substantial tonal reductions of this Trailing Edge Rotor Blowing (TERB) fan. This report documents the broadband characteristics of TERB. The Active Noise Control Fan (ANCF), located at the NASA Glenn Research Center, was used as the proof-of-concept test bed. Two-component hotwire data behind the rotor, unsteady surface pressures on the stator vane, and farfield directivity acoustic data were acquired at blowing rates of 1.1, 1.5, and 1.8 percent of the total fan mass flow. The results indicate a substantial reduction in the rotor wake turbulent velocity and in the stator vane unsteady surface pressures. Based on the physics of the noise generation, these indirect measurements indicate the prospect of broadband noise reduction. However, since the broadband noise generated by the ANCF is rotor-dominated, any change in the rotor-stator interaction broadband noise levels is barely distinguishable in the farfield measurements.

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

PubMed

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.

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

PubMed

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.

Fully Phase-Encoded MRI Near Metallic Implants Using Ultrashort Echo Times and Broadband Excitation

PubMed Central

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

2017-01-01

Purpose To develop a fully phase-encoded MRI method for distortion-free imaging near metallic implants, in clinically feasible acquisition times. Theory and Methods 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. Results Phantom and in vivo acquisitions were used to describe the relationship among excitation bandwidth, signal loss near metallic implants, and T1 weighting. Shorter radiofrequency pulses captured signal closer to the implant by improving spectral coverage and allowing shorter echo times, whereas longer pulses improved T1 weighting through larger maximum attainable flip angles. Comparisons of fully phase-encoded acquisition with broadband excitation and ultrashort echo times to T1-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. Conclusions 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 000:000–000, 2017. PMID:28833407

Flexible, transparent and ultra-broadband photodetector based on large-area WSe2 film for wearable devices

NASA Astrophysics Data System (ADS)

Zheng, Zhaoqiang; Zhang, Tanmei; Yao, Jiandomg; Zhang, Yi; Xu, Jiarui; Yang, Guowei

2016-06-01

Although two-dimensional (2D) materials have attracted considerable research interest for use in the development of innovative wearable optoelectronic systems, the integrated optoelectronic performance of 2D materials photodetectors, including flexibility, transparency, broadband response and stability in air, remains quite low to date. Here, we demonstrate a flexible, transparent, high-stability and ultra-broadband photodetector made using large-area and highly-crystalline WSe2 films that were prepared by pulsed-laser deposition (PLD). Benefiting from the 2D physics of WSe2 films, this device exhibits excellent average transparency of 72% in the visible range and superior photoresponse characteristics, including an ultra-broadband detection spectral range from 370 to 1064 nm, reversible photoresponsivity approaching 0.92 A W-1, external quantum efficiency of up to 180% and a relatively fast response time of 0.9 s. The fabricated photodetector also demonstrates outstanding mechanical flexibility and durability in air. Also, because of the wide compatibility of the PLD-grown WSe2 film, we can fabricate various photodetectors on multiple flexible or rigid substrates, and all these devices will exhibit distinctive switching behavior and superior responsivity. These indicate a possible new strategy for the design and integration of flexible, transparent and broadband photodetectors based on large-area WSe2 films, with great potential for practical applications in the wearable optoelectronic devices.

Broadband ion mobility deconvolution for rapid analysis of complex mixtures.

PubMed

Pettit, Michael E; Brantley, Matthew R; Donnarumma, Fabrizio; Murray, Kermit K; Solouki, Touradj

2018-05-04

High resolving power ion mobility (IM) allows for accurate characterization of complex mixtures in high-throughput IM mass spectrometry (IM-MS) experiments. We previously demonstrated that pure component IM-MS data can be extracted from IM unresolved post-IM/collision-induced dissociation (CID) MS data using automated ion mobility deconvolution (AIMD) software [Matthew Brantley, Behrooz Zekavat, Brett Harper, Rachel Mason, and Touradj Solouki, J. Am. Soc. Mass Spectrom., 2014, 25, 1810-1819]. In our previous reports, we utilized a quadrupole ion filter for m/z-isolation of IM unresolved monoisotopic species prior to post-IM/CID MS. Here, we utilize a broadband IM-MS deconvolution strategy to remove the m/z-isolation requirement for successful deconvolution of IM unresolved peaks. Broadband data collection has throughput and multiplexing advantages; hence, elimination of the ion isolation step reduces experimental run times and thus expands the applicability of AIMD to high-throughput bottom-up proteomics. We demonstrate broadband IM-MS deconvolution of two separate and unrelated pairs of IM unresolved isomers (viz., a pair of isomeric hexapeptides and a pair of isomeric trisaccharides) in a simulated complex mixture. Moreover, we show that broadband IM-MS deconvolution improves high-throughput bottom-up characterization of a proteolytic digest of rat brain tissue. To our knowledge, this manuscript is the first to report successful deconvolution of pure component IM and MS data from an IM-assisted data-independent analysis (DIA) or HDMSE dataset.

Anisotropic Broadband Photoresponse of Layered Type-II Weyl Semimetal MoTe2.

PubMed

Lai, Jiawei; Liu, Xin; Ma, Junchao; Wang, Qinsheng; Zhang, Kenan; Ren, Xiao; Liu, Yinan; Gu, Qiangqiang; Zhuo, Xiao; Lu, Wei; Wu, Yang; Li, Yuan; Feng, Ji; Zhou, Shuyun; Chen, Jian-Hao; Sun, Dong

2018-05-01

Photodetectors based on Weyl semimetal promise extreme performance in terms of highly sensitive, broadband and self-powered operation owing to its extraordinary material properties. Layered Type-II Weyl semimetal that break Lorentz invariance can be further integrated with other two-dimensional materials to form van der Waals heterostructures and realize multiple functionalities inheriting the advantages of other two-dimensional materials. Herein, we report the realization of a broadband self-powered photodetector based on Type-II Weyl semimetal T d -MoTe 2 . The prototype metal-MoTe 2 -metal photodetector exhibits a responsivity of 0.40 mA W -1 and specific directivity of 1.07 × 10 8 Jones with 43 μs response time at 532 nm. Broadband responses from 532 nm to 10.6 μm are experimentally tested with a potential detection range extendable to far-infrared and terahertz. Furthermore, we identify the response of the detector is polarization angle sensitive due to the anisotropic response of MoTe 2 . The anisotropy is found to be wavelength dependent, and the degree of anisotropy increases as the excitation wavelength gets closer to the Weyl nodes. In addition, with power and temperature dependent photoresponse measurements, the photocurrent generation mechanisms are investigated. Our results suggest this emerging class of materials can be harnessed for broadband angle sensitive, self-powered photodetection with decent responsivities. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Improved Broadband Liner Optimization Applied to the Advanced Noise Control Fan

NASA Technical Reports Server (NTRS)

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

2014-01-01

The broadband component of fan noise has grown in relevance with the utilization of increased bypass ratio and advanced fan designs. Thus, while the attenuation of fan tones remains paramount, the ability to simultaneously reduce broadband fan noise levels has become more desirable. This paper describes improvements to a previously established broadband acoustic liner optimization process using the Advanced Noise Control Fan rig as a demonstrator. Specifically, in-duct attenuation predictions with a statistical source model are used to obtain optimum impedance spectra over the conditions of interest. The predicted optimum impedance information is then used with acoustic liner modeling tools to design liners aimed at producing impedance spectra that most closely match the predicted optimum values. Design selection is based on an acceptance criterion that provides the ability to apply increased weighting to specific frequencies and/or operating conditions. Constant-depth, double-degree of freedom and variable-depth, multi-degree of freedom designs are carried through design, fabrication, and testing to validate the efficacy of the design process. Results illustrate the value of the design process in concurrently evaluating the relative costs/benefits of these liner designs. This study also provides an application for demonstrating the integrated use of duct acoustic propagation/radiation and liner modeling tools in the design and evaluation of novel broadband liner concepts for complex engine configurations.

Broadband enhanced transmission of acoustic waves through serrated metal gratings

NASA Astrophysics Data System (ADS)

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

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

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

NASA Astrophysics Data System (ADS)

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.

Broad-band seismic analysis and modeling of the 2015 Taan Fjord, Alaska landslide using Instaseis

NASA Astrophysics Data System (ADS)

Gualtieri, Lucia; Ekström, Göran

2018-06-01

We carry out a broad-band analysis of the seismic signals generated by a massive landslide that occurred near Icy Bay (Alaska) on 2015 October 17. The event generated seismic signals recorded globally. Using Instaseis, a recently developed tool for rapid computation of complete broad-band synthetic seismograms, we simulate the seismic wave propagation between the event and five seismic stations located around the landslide. By modeling the broad-band seismograms in the period band 5-200 s, we reconstruct by inversion a time-varying point force to characterize the landslide time history. We compute the broad-band spectrum of the landslide force history and find that it has a corner period of about 100 s, corresponding to the duration of sliding. In contrast with standard earthquakes, the landslide force spectrum below the corner frequency decays as ω, while the spectral amplitudes at higher frequencies is proportional to ω-2, similar to the rate of spectral decay seen in earthquakes. From the inverted force history and an estimate of the final run-out distance, we deduce the mass, the trajectory and characteristics of the landslide dynamics associated with the centre of mass, such as acceleration, velocity, displacement and friction. Inferring an effective run-out distance of ˜900 m from a satellite image, we estimate a landslide mass of ˜150 million metric tons.

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

NASA Astrophysics Data System (ADS)

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

2013-03-01

We propose a counter-intuitive mechanism of constructing an ultrathin broadband transparent device with two perfect blackbodies. By introducing hybridization of plasmon modes, resonant modes with different symmetries coexist in this system. A broadband transmission spectrum in the near infrared regime is achieved through controlling their coupling strengths, which is governed by the thickness of high refractive index layer. Meanwhile, the transparency bandwidth is found to be tunable in a large range by varying the geometric dimension. More significantly, from the point view of applications, the proposed method of achieving broadband transparency can perfectly tolerate the misalignment and asymmetry of periodic nanoparticles on the top and bottom, which is empowered by the unique dual of coupling-in and coupling-out processes within the pair of blackbodies. Moreover, roughness has little influence on its transmission performance. According to the coupled mode theory, the distinguished transmittance performance is physically interpreted by the radiative decay rate of the entire system. In addition to the feature of uniquely robust broadband transparency, such a ultrathin seamless nanostructure (in the presence of a uniform silver layer) also provides polarization-independent and angle-independent operations. Therefore, it may power up a wide spectrum of exciting applications in thin film protection, touch screen techniques, absorber-emitter transformation, etc.We propose a counter-intuitive mechanism of constructing an ultrathin broadband transparent device with two perfect blackbodies. By introducing hybridization of plasmon modes, resonant modes with different symmetries coexist in this system. A broadband transmission spectrum in the near infrared regime is achieved through controlling their coupling strengths, which is governed by the thickness of high refractive index layer. Meanwhile, the transparency bandwidth is found to be tunable in a large range by varying the geometric dimension. More significantly, from the point view of applications, the proposed method of achieving broadband transparency can perfectly tolerate the misalignment and asymmetry of periodic nanoparticles on the top and bottom, which is empowered by the unique dual of coupling-in and coupling-out processes within the pair of blackbodies. Moreover, roughness has little influence on its transmission performance. According to the coupled mode theory, the distinguished transmittance performance is physically interpreted by the radiative decay rate of the entire system. In addition to the feature of uniquely robust broadband transparency, such a ultrathin seamless nanostructure (in the presence of a uniform silver layer) also provides polarization-independent and angle-independent operations. Therefore, it may power up a wide spectrum of exciting applications in thin film protection, touch screen techniques, absorber-emitter transformation, etc. Electronic supplementary information (ESI) available: Comparison of transmittance spectra between structures with and without Ag film at the middle. Transmittance spectra of structures with different thicknesses of Ag film. See DOI: 10.1039/c3nr34278f

Bandwidth, Broadband, and Planning for Public Access

ERIC Educational Resources Information Center

Blowers, Helene

2012-01-01

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

Expanding Access

ERIC Educational Resources Information Center

Roach, Ronald

2007-01-01

There is no question that the United States lags behind most industrialized nations in consumer access to broadband Internet service. For many policy makers and activists, this shortfall marks the latest phase in the struggle to overcome the digital divide. To remedy this lack of broadband affordability and availability, one start-up firm--with…

Global Interoperability of Broadband Networks (GIBN): Project Overview

NASA Technical Reports Server (NTRS)

DePaula, Ramon P.

1998-01-01

Various issues associated with the Global Interoperability of Broadband Networks (GIBN) are presented in viewgraph form. Specific topics include GIBN principles, objectives and goals, and background. GIBN/NASA status, the Transpacific High Definition Video experiment, GIBN experiment selection criteria, satellite industry involvement, and current experiments associated with GIBN are also discussed.

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

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-20

... Broadband Availability Through Digital Literacy Training, et al. AGENCY: Federal Communications Commission...: Federal Communications Commission, 445 12th Street SW., Washington, DC 20554. FOR FURTHER INFORMATION.... SUPPLEMENTARY INFORMATION: This is a summary of Commission's document, Report No. 2948, released April 5, 2012...

Broadband nanoindentation of glassy polymers: Part II. Viscoplasticity

Treesearch

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

2012-01-01

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

47 CFR 90.1407 - Spectrum use in the network.

Code of Federal Regulations, 2012 CFR

2012-10-01

... exclusion and/or immediate preemption of any commercial use on a dynamic, real-time priority basis, and to... network. (a) Spectrum use. The Shared Wireless Broadband Network will operate using spectrum associated... Block licensee and the Operating Company for the entire remaining term of the Public Safety Broadband...

47 CFR 90.528 - Public safety broadband license.

Code of Federal Regulations, 2010 CFR

2010-10-01

... financial and operational information. The Public Safety Broadband Licensee shall submit, on a quarterly basis, a full financial accounting to the Commission, in a format to be set forth in the Network Sharing Agreement, and as approved by the Commission. Such quarterly financial reports shall be filed with the...

77 FR 35623 - Connect America Fund; a National Broadband Plan for Our Future; Establishing Just and Reasonable...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-14

... America Fund; a National Broadband Plan for Our Future; Establishing Just and Reasonable Rates for Local Exchange Carriers; High-Cost Universal Service Support AGENCY: Federal Communications Commission. ACTION... Fund, Report and Order (Order). The Commission submitted revisions to this information collection under...

77 FR 30903 - Connect America Fund; A National Broadband Plan for Our Future; Establishing Just and Reasonable...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-24

... America Fund; A National Broadband Plan for Our Future; Establishing Just and Reasonable Rates for Local Exchange Carriers; High-Cost Universal Service Support AGENCY: Federal Communications Commission. ACTION... of information collections associated with the Commission's; Connect America Fund; A National...

Public Address Set AN/UIQ-10 (XLW-1)

DTIC Science & Technology

1972-01-01

case. /,320 Hz No visible indication. Major Horizontal Broadband Resonance Resonance center located 300 to 500 peak at on case over relay bracket. ’ 375 ... Hz No visible indication. Minor Horizontal Broadband Resonance Resonance center located 150 to 190 peak at case over relay bracket. � Hz Slight

77 FR 39241 - Information Collection(s) Being Reviewed by the Federal Communications Commission, Comments...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-02

... Digital Literacy Training. Form Number: FCC Form 497; Low-Income Broadband Pilot Program Reporting Form... Board on Universal Service; Advancing Broadband Availability Through Digital Literacy Training, WC... ETCs to include plain, easy-to-understand language in all of their Lifeline marketing materials to...

75 FR 29516 - Broadband Researchers' Data Workshop

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-26

... Population Survey Computer and Internet Use Supplement survey instrument (pp. 8 through 23), http://www.bls... adoption. Current and detailed data by U.S. households' and persons' usage of and access to broadband is... propose, with rationale, the type of Internet usage data that could be usefully collected through...

75 FR 17799 - AB Liquidating Corp. (f/k/a Adaptive Broadband Corp.), Globalnet Corp., Greenland Corp...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-07

... SECURITIES AND EXCHANGE COMMISSION [File No. 500-1] AB Liquidating Corp. (f/k/a Adaptive Broadband Corp.), Globalnet Corp., Greenland Corp., KeraVision, Inc., Lifespan, Inc., STAR Telecommunications... concerning the securities of STAR Telecommunications, Inc. because it has not filed any periodic reports...

Exploring the Digital Nation: Home Broadband Internet Adoption in the United States

ERIC Educational Resources Information Center

National Telecommunications and Information Administration, 2010

2010-01-01

The Internet has revolutionized the social and economic environment in which people live by providing an alternative or supplemental channel for communication, gathering and disseminating information, entertainment, commerce, and education. Household use of high-speed, or broadband, Internet services has risen dramatically during this decade which…

Predicting Noise From Wind Turbines

NASA Technical Reports Server (NTRS)

Grosveld, Ferdinand W.

1990-01-01

Computer program WINDY predicts broadband noise spectra of horizontal-axis wind-turbine generators. Enables adequate assessment of impact of broadband wind-turbine noise. Effects of turbulence, trailing-edge wakes, and bluntness taken into account. Program has practical application in design and siting of wind-turbine machines acceptable to community. Written in GW-Basic.

47 CFR 1.9005 - Included services.

Code of Federal Regulations, 2012 CFR

2012-10-01

... this subpart apply to the following services, which include Wireless Radio Services in which commercial... chapter); (h) The Broadband Radio Service (part 27 of this chapter); (i) The Educational Broadband Service (part 27 of this chapter); (j) The Wireless Communications Service in the 698-746 MHz band (part 27 of...

47 CFR 1.9005 - Included services.

Code of Federal Regulations, 2013 CFR

2013-10-01

... this subpart apply to the following services, which include Wireless Radio Services in which commercial... chapter); (h) The Broadband Radio Service (part 27 of this chapter); (i) The Educational Broadband Service (part 27 of this chapter); (j) The Wireless Communications Service in the 698-746 MHz band (part 27 of...

75 FR 9586 - Solicitation of Participation In and Public Meeting to Discuss Public Safety 700 MHz Broadband...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-03

... Demonstration Network AGENCY: National Institute of Standards and Technology, Department of Commerce. ACTION... (NIST) announces the building of a 700 MHz Public Safety Broadband Demonstration Network (Demonstration Network), which will provide manufacturers and first responders a location for early deployment of their...

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

ERIC Educational Resources Information Center

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

2010-01-01

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

47 CFR 24.714 - Partitioned licenses and disaggregated spectrum.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 47 Telecommunication 2 2013-10-01 2013-10-01 false Partitioned licenses and disaggregated spectrum... Partitioned licenses and disaggregated spectrum. (a) Eligibility. (1) Parties seeking approval for... § 24.839. (2) Broadband PCS licensees in spectrum blocks A, B, D, and E and broadband PCS C and F block...

47 CFR 24.714 - Partitioned licenses and disaggregated spectrum.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 2 2010-10-01 2010-10-01 false Partitioned licenses and disaggregated spectrum... Partitioned licenses and disaggregated spectrum. (a) Eligibility. (1) Parties seeking approval for... § 24.839. (2) Broadband PCS licensees in spectrum blocks A, B, D, and E and broadband PCS C and F block...

47 CFR 24.714 - Partitioned licenses and disaggregated spectrum.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 47 Telecommunication 2 2014-10-01 2014-10-01 false Partitioned licenses and disaggregated spectrum... Partitioned licenses and disaggregated spectrum. (a) Eligibility. (1) Parties seeking approval for... § 24.839. (2) Broadband PCS licensees in spectrum blocks A, B, D, and E and broadband PCS C and F block...

47 CFR 24.714 - Partitioned licenses and disaggregated spectrum.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 47 Telecommunication 2 2012-10-01 2012-10-01 false Partitioned licenses and disaggregated spectrum... Partitioned licenses and disaggregated spectrum. (a) Eligibility. (1) Parties seeking approval for... § 24.839. (2) Broadband PCS licensees in spectrum blocks A, B, D, and E and broadband PCS C and F block...

47 CFR 24.714 - Partitioned licenses and disaggregated spectrum.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 2 2011-10-01 2011-10-01 false Partitioned licenses and disaggregated spectrum... Partitioned licenses and disaggregated spectrum. (a) Eligibility. (1) Parties seeking approval for... § 24.839. (2) Broadband PCS licensees in spectrum blocks A, B, D, and E and broadband PCS C and F block...

78 FR 73144 - Acceleration of Broadband Deployment by Improving Wireless Facilities Siting Policies

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-05

..., ground-based enclosures, battery back-up power systems, grounding equipment, power transfer switch, and... No. 11-59; FCC 13-122] Acceleration of Broadband Deployment by Improving Wireless Facilities Siting... of new wireless facilities and on rules to implement statutory provisions governing State and local...

47 CFR 27.1202 - Cable/BRS cross-ownership.

Code of Federal Regulations, 2010 CFR

2010-10-01

... MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Broadband Radio Service and Educational Broadband Service § 27... modifications, assignments or transfers of control by cable operators of BRS stations shall include a showing... who holds or shares the power to vote such stock, to any person who has the sole power to sell such...

Characterisation of optical filters for broadband UVA radiometer

NASA Astrophysics Data System (ADS)

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.

76 FR 14664 - Notice of Public Information Collection(s) Being Reviewed by the Federal Communications...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-17

... public safety broadband networks to employ the Long Term Evolution (LTE) broadband standard, specifically... and Order further requires that these networks support certain LTE interfaces. These requirements were... network deployment, that its network will support the required LTE interfaces. This requirement will...

75 FR 42727 - Implementing the National Broadband Plan; Comment Period Extension

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-22

..., state, and private entities seek to develop Smart Grid technologies. The second RFI requested information on the evolving needs of electric utilities as Smart Grid technologies are more broadly deployed... accept reply comments, data, and information regarding the National Broadband Plan RFI: Data Access and...

78 FR 143 - Desert Mining, Inc., Eagle Broadband, Inc., Endovasc, Inc., Environmental Oil Processing...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-02

... SECURITIES AND EXCHANGE COMMISSION [File No. 500-1] Desert Mining, Inc., Eagle Broadband, Inc., Endovasc, Inc., Environmental Oil Processing Technology Corp., Falcon Ridge Development, Inc., Fellows... Environmental Oil Processing Technology Corp. because it has not filed any periodic reports since the period...

Broadband Behavior Rating Scales as Screeners for Autism?

ERIC Educational Resources Information Center

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

2014-01-01

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

7 CFR 1739.11 - Eligible project.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 11 2010-01-01 2010-01-01 false Eligible project. 1739.11 Section 1739.11 Agriculture... BROADBAND GRANT PROGRAM Community Connect Grant Program § 1739.11 Eligible project. To be eligible for a grant, the Project must: (a) Serve a Rural Area where Broadband Transmission Service does not currently...

Gravitation research

NASA Technical Reports Server (NTRS)

Weiss, R.; Muehlner, D. J.; Benford, R. L.; Owens, D. K.; Pierre, N. A.; Rosenbluh, M.

1972-01-01

Balloon measurements were made of the far infrared background radiation. The radiometer used and its calibration are discussed. An electromagnetically coupled broadband gravitational antenna is also considered. The proposed antenna design and noise sources in the antenna are reviewed. A comparison is made between interferometric broadband and resonant bar antennas for the detection of gravitational wave pulses.

7 CFR 1739.11 - Eligible project.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 11 2011-01-01 2011-01-01 false Eligible project. 1739.11 Section 1739.11 Agriculture... BROADBAND GRANT PROGRAM Community Connect Grant Program § 1739.11 Eligible project. To be eligible for a grant, the Project must: (a) Serve a Rural Area where Broadband Transmission Service does not currently...

7 CFR 1739.11 - Eligible project.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 11 2012-01-01 2012-01-01 false Eligible project. 1739.11 Section 1739.11 Agriculture... BROADBAND GRANT PROGRAM Community Connect Grant Program § 1739.11 Eligible project. To be eligible for a grant, the Project must: (a) Serve a Rural Area where Broadband Transmission Service does not currently...

7 CFR 1739.11 - Eligible project.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 11 2013-01-01 2013-01-01 false Eligible project. 1739.11 Section 1739.11 Agriculture... BROADBAND GRANT PROGRAM Community Connect Grant Program § 1739.11 Eligible project. To be eligible for a grant, the Project must: (a) Serve a Rural Area where Broadband Transmission Service does not currently...

Method and means of transmitting and receiving broad-band unipolar, ultrasonic pulses for ultrasonic inspection

DOEpatents

Thompson, D.O.; Hsu, D.K.

1993-12-14

The invention includes a means and method for transmitting and receiving broadband, unipolar, ultrasonic pulses for ultrasonic inspection. The method comprises generating a generally unipolar ultrasonic stress pulse from a low impedance voltage pulse transmitter along a low impedance electrical pathway to an ultrasonic transducer, and receiving the reflected echo of the pulse by the transducer, converting it to a voltage signal, and passing it through a high impedance electrical pathway to an output. The means utilizes electrical components according to the method. The means and method allow a single transducer to be used in a pulse/echo mode, and facilitates alternatingly transmitting and receiving the broadband, unipolar, ultrasonic pulses. 25 figures.

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

NASA Astrophysics Data System (ADS)

Cong, Hai-fang

2014-12-01

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

Flexible thin broadband microwave absorber based on a pyramidal periodic structure of lossy composite.

PubMed

Huang, Yixing; Yuan, Xujin; Wang, Changxian; Chen, Mingji; Tang, Liqun; Fang, Daining

2018-06-15

Microwave absorber with broadband absorption and thin thickness is one of the main research interests in this field. A flexible ultrathin and broadband microwave absorber comprising multiwall carbon nanotubes, spherical carbonyl iron, and silicone rubber is fabricated in a newly proposed pyramidal spatial periodic structure (SPS). The SPS with equivalent thickness of 3.73 mm covers the -10  dB and -15  dB absorption bandwidth in the frequency range 2-40 GHz and 10-40 GHz, respectively. The excellent absorption performance is achieved by concentration and dissipation of the electromagnetic field inside different parts of the magnetic-dielectric lossy protrusions in different frequency ranges.

Modulated near-field spectral extraction of broadband mid-infrared signals with a ceramic light source.

PubMed

Ishikawa, Michio; Katsura, Makoto; Nakashima, Satoru; Aizawa, Kento; Inoue, Tsutomu; Okamura, Hidekazu; Ikemoto, Yuka

2011-06-20

In order to obtain broadband near-field infrared (IR) spectra, a Fourier-transform IR spectrometer (FT-IR) and a ceramic light source were used with a scattering-type scanning near-field optical microscope (s-SNOM). To suppress the background (far-field) scattering, the distance between the scattering probe and the sample was modulated with frequency Ω by a piezo-electric actuator, and the Ω component was extracted from the signal with a lock-in detection. With Ω=30 kHz, a peak-to-peak modulation amplitude of 198 nm, and a probe with smooth surface near the tip, broadband near-field IR spectra could be obtained in the 1200-2500 cm(-1).

Broadband near-field mid-infrared spectroscopy and application to phonon resonances in quartz.

PubMed

Ishikawa, Michio; Katsura, Makoto; Nakashima, Satoru; Ikemoto, Yuka; Okamura, Hidekazu

2012-05-07

Infrared (IR) spectroscopy is a versatile analytical method and nano-scale spatial resolution could be achieved by scattering type near-field optical microscopy (s-SNOM). The spectral bandwidth was, however, limited to approximately 300 cm(-1) with a laser light source. In the present study, the development of a broadband mid-IR near-field spectroscopy with a ceramic light source is demonstrated. A much wider bandwidth (at least 3000 to 1000 cm(-1)) is achieved with a ceramic light source. The experimental data on quartz Si-O phonon resonance bands are well reproduced by theoretical simulations indicating the validity of the present broadband near-field IR spectroscopy.

Scanning, non-contact, hybrid broadband diffuse optical spectroscopy and diffuse correlation spectroscopy system.

PubMed

Johansson, Johannes D; Mireles, Miguel; Morales-Dalmau, Jordi; Farzam, Parisa; Martínez-Lozano, Mar; Casanovas, Oriol; Durduran, Turgut

2016-02-01

A scanning system for small animal imaging using non-contact, hybrid broadband diffuse optical spectroscopy (ncDOS) and diffuse correlation spectroscopy (ncDCS) is presented. The ncDOS uses a two-dimensional spectrophotometer retrieving broadband (610-900 nm) spectral information from up to fifty-seven source-detector distances between 2 and 5 mm. The ncDCS data is simultaneously acquired from four source-detector pairs. The sample is scanned in two dimensions while tracking variations in height. The system has been validated with liquid phantoms, demonstrated in vivo on a human fingertip during an arm cuff occlusion and on a group of mice with xenoimplanted renal cell carcinoma.

Investigation of broadband terahertz generation from metasurface

DOE PAGES

Fang, Ming; Niu, Kaikun; Huang, ZHixiang; ...

2018-01-01

The nonlinear metamaterials have been shown to provide nonlinear properties with high nonlinear conversion efficiency and in a myriad of light manipulation. Here we study terahertz generation from nonlinear metasurface consisting of single layer nanoscale split-ring resonator array. The terahertz generation due to optical rectification by the second-order nonlinearity of the split-ring resonator is investigated by a time-domain implementation of the hydrodynamic model for electron dynamics in metal. The results show that the nonlinear metasurface enables us to generate broadband terahertz radiation and free from quasi-phase-matching conditions. The proposed scheme provides a new concept of broadband THz source and designingmore » nonlinear plasmonic metamaterials.« less

Hyper-spectral imaging in scanning-confocal-fluorescence microscopy using a novel broadband diffractive optic

NASA Astrophysics Data System (ADS)

Wang, Peng; Ebeling, Carl G.; Gerton, Jordan; Menon, Rajesh

In this paper, we demonstrate hyper-spectral imaging of fluorescent microspheres in a scanning-confocal-fluorescence microscope by spatially dispersing the spectra using a novel broadband diffractive optic, and applying a nonlinear optimization technique to extract the full-incident spectra. This broadband diffractive optic has a designed optical efficiency of over 90% across the entire visible spectrum. We used this technique to create two-color images of two fluorophores and also extracted their emission spectra with good fidelity. This method can be extended to image both spatially and spectrally overlapping fluorescent samples. Full control in the number of emission spectra and the feasibility of enhanced imaging speed are demonstrated as well.

Investigation of broadband terahertz generation from metasurface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fang, Ming; Niu, Kaikun; Huang, ZHixiang

The nonlinear metamaterials have been shown to provide nonlinear properties with high nonlinear conversion efficiency and in a myriad of light manipulation. Here we study terahertz generation from nonlinear metasurface consisting of single layer nanoscale split-ring resonator array. The terahertz generation due to optical rectification by the second-order nonlinearity of the split-ring resonator is investigated by a time-domain implementation of the hydrodynamic model for electron dynamics in metal. The results show that the nonlinear metasurface enables us to generate broadband terahertz radiation and free from quasi-phase-matching conditions. The proposed scheme provides a new concept of broadband THz source and designingmore » nonlinear plasmonic metamaterials.« less

A physical parameter method for the design of broad-band X-ray imaging systems to do coronal plasma diagnostics

NASA Technical Reports Server (NTRS)

Kahler, S.; Krieger, A. S.

1978-01-01

The technique commonly used for the analysis of data from broad-band X-ray imaging systems for plasma diagnostics is the filter ratio method. This requires the use of two or more broad-band filters to derive temperatures and line-of-sight emission integrals or emission measure distributions as a function of temperature. Here an alternative analytical approach is proposed in which the temperature response of the imaging system is matched to the physical parameter being investigated. The temperature response of a system designed to measure the total radiated power along the line of sight of any coronal structure is calculated. Other examples are discussed.

Broadband mid-infrared measurements for shock induced chemistry

NASA Astrophysics Data System (ADS)

McGrane, Shawn; Bowlan, Pamela; Brown, Kathryn; Bolme, Cynthia; Cawkwell, Marc

2017-06-01

Vibrational absorption spectroscopy across the mid-infrared range is a ubiquitous diagnostic of chemical effects due to its sensitivity to small variations in bonding. At the high temperatures and pressures relevant to shock induced chemistry, vibrational spectral peaks become very broad, and accessing as much spectral range as possible with high time resolution can significantly aid in deducing chemical dynamics. Here, we report experiments using broadband (<500 cm-1 to >2000 cm-1) mid-infrared femtosecond supercontinua created by four wave mixing in filaments to perform absorption spectroscopy. These broadband mid-infrared supercontinua are detected through upconversion to visible light. Initial efforts to utilize these methods for measurement of chemical dynamics in shocked nitromethane will be reported.

Water metamaterial for ultra-broadband and wide-angle absorption.

PubMed

Xie, Jianwen; Zhu, Weiren; Rukhlenko, Ivan D; Xiao, Fajun; He, Chong; Geng, Junping; Liang, Xianling; Jin, Ronghong; Premaratne, Malin

2018-02-19

A subwavelength water metamaterial is proposed and analyzed for ultra-broadband perfect absorption at microwave frequencies. We experimentally demonstrate that this metamaterial shows over 90% absorption within almost the entire frequency band of 12-29.6 GHz. It is also shown that the proposed metamaterial exhibits a good thermal stability with its absorption performance almost unchanged for the temperature range from 0 to 100°C. The study of the angular tolerance of the metamaterial absorber shows its ability of working at wide angles of incidence. Given that the proposed water metamaterial absorber is low-cost and easy for manufacture, we envision it may find numerous applications in electromagnetics such as broadband scattering reduction and electromagnetic energy harvesting.

General design method of ultra-broadband perfect absorbers based on magnetic polaritons.

PubMed

Liu, Yuanbin; Qiu, Jun; Zhao, Junming; Liu, Linhua

2017-10-02

Starting from one-dimensional gratings and the theory of magnetic polaritons (MPs), we propose a general design method of ultra-broadband perfect absorbers. Based on the proposed design method, the obtained absorber can keep the spectrum-average absorptance over 99% at normal incidence in a wide range of wavelengths; this work simultaneously reveals the robustness of the absorber to incident angles and polarization angles of incident light. Furthermore, this work shows that the spectral band of perfect absorption can be flexibly extended to near the infrared regime by adjusting the structure dimension. The findings of this work may facilitate the active design of ultra-broadband absorbers based on plasmonic nanostructures.

Method and means of transmitting and receiving broad-band unipolar, ultrasonic pulses for ultrasonic inspection

DOEpatents

Thompson, Donald O.; Hsu, David K.

1993-12-14

The invention includes a means and method for transmitting and receiving broadband, unipolar, ultrasonic pulses for ultrasonic inspection. The method comprises generating a generally unipolar ultrasonic stress pulse from a low impedance voltage pulse transmitter along a low impedance electrical pathway to an ultrasonic transducer, and receiving the reflected echo of the pulse by the transducer, converting it to a voltage signal, and passing it through a high impedance electrical pathway to an output. The means utilizes electrical components according to the method. The means and method allow a single transducer to be used in a pulse/echo mode, and facilitates alternatingly transmitting and receiving the broadband, unipolar, ultrasonic pulses.

Revisiting NMR composite pulses for broadband 2H excitation

PubMed Central

Shen, Ming; Roopchand, Rabia; Mananga, Eugene S.; Amoureux, Jean-Paul; Chen, Qun; Boutis, Gregory S.; Hu, Bingwen

2014-01-01

Quadrupolar echo NMR spectroscopy of static solids often requires RF excitation that covers spectral widths exceeding 100 kHz, which is difficult to obtain due to instrumental limitations. In this work we revisit four well-known composite pulses (COM-I, II, III and IV) for broadband excitation in deuterium quadrupolar echo spectroscopy. These composite pulses are combined with several phase cycling schemes that were previously shown to decrease finite pulse width distortions in deuterium solid-echo experiments performed with two single pulses. The simulations and experiments show that COM-II and IV composite pulses combined with an 8-step phase cycling aid in achieving broadband excitation with limited pulse width distortions. PMID:25583576

Efficient composite broadband polarization retarders and polarization filters

NASA Astrophysics Data System (ADS)

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.).

Investigation of broadband terahertz generation from metasurface

DOE PAGES

Fang, Ming; Niu, Kaikun; Huang, ZHixiang; ...

2018-05-21

The nonlinear metamaterials have been shown to provide nonlinear properties with high nonlinear conversion efficiency and in a myriad of light manipulation. Here we study terahertz generation from nonlinear metasurface consisting of single layer nanoscale split-ring resonator array. The terahertz generation due to optical rectification by the second-order nonlinearity of the split-ring resonator is investigated by a time-domain implementation of the hydrodynamic model for electron dynamics in metal. The results show that the nonlinear metasurface enables us to generate broadband terahertz radiation and free from quasi-phase-matching conditions. The proposed scheme provides a new concept of broadband THz source and designingmore » nonlinear plasmonic metamaterials.« less

The Ground-Based Transmission Spectrum of HD 189733b as Generated Through Multiple Broadband Filter Observations

NASA Astrophysics Data System (ADS)

Kasper, David; Cole, Jackson L.; Gardner, Cristilyn N.; Garver, Bethany; Jarka, Kyla L.; Kar, Aman; McGough, Aylin M.; PeQueen, David J.; Rivera, Daniel Ivan; Jang-Condell, Hannah; Kobulnicky, Henry A.; Dale, Daniel A.

2018-06-01

We present new multi-broadband transit photometry of HD 189733b observed with the Wyoming Infrared Observatory. With an ensemble of Sloan filter observations across multiple transits we have created an ultra-low resolution transmission spectrum to discern the nature of the exoplanet atmosphere. This data set exemplifies the capabilities of the 2.3 m observatory. The analysis was performed with a Markov-Chain Monte-Carlo method assisted by a Gaussian-processes regression model. These observations were taken as part of the University of Wyoming's 2017 Research Experience for Undergraduates (REU) and represent one of multiple hot Jupiter exoplanet targets for which we have transit event observations in multiple broadband filters.

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

ERIC Educational Resources Information Center

Peters, Robert W.

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

47 CFR 90.1403 - Public safety broadband license conditions.

Code of Federal Regulations, 2010 CFR

2010-10-01

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

47 CFR 90.1403 - Public safety broadband license conditions.

Code of Federal Regulations, 2011 CFR

2011-10-01

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

47 CFR 90.1403 - Public safety broadband license conditions.

Code of Federal Regulations, 2012 CFR

2012-10-01

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

Utilization of KSC Present Broadband Communications Data System for Digital Video Services

NASA Technical Reports Server (NTRS)

Andrawis, Alfred S.

2002-01-01

This report covers a visibility study of utilizing present KSC broadband communications data system (BCDS) for digital video services. Digital video services include compressed digital TV delivery and video-on-demand. Furthermore, the study examines the possibility of providing interactive video on demand to desktop personal computers via KSC computer network.

The Glenview Model: Community Networking via Broadband Cable.

ERIC Educational Resources Information Center

Mundt, John P.

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

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

ERIC Educational Resources Information Center

Sisneros, Lauren; Sponsler, Brian A.

2016-01-01

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

A Blueprint for Big Broadband. An EDUCAUSE White Paper

ERIC Educational Resources Information Center

Windhausen, John, Jr.

2008-01-01

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

78 FR 9035 - Renewal and Revision of a Previously Approved Information Collection; Comment Request; State...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-07

... maximum advertised speed, technology type and spectrum (if applicable) for each broadband provider... funding to collect the maximum advertised speed and technology type to which various classes of Community... businesses use the data to identify where broadband is available, the advertised speeds and other information...

47 CFR 24.238 - Emission limitations for Broadband PCS equipment.

Code of Federal Regulations, 2012 CFR

2012-10-01

... Broadband Personal Communications Service. (a) Out of band emissions. The power of any emission outside of the authorized operating frequency ranges must be attenuated below the transmitting power (P) by a factor of at least 43 + 10 log(P) dB. (b) Measurement procedure. Compliance with these rules is based on...

47 CFR 24.238 - Emission limitations for Broadband PCS equipment.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Broadband Personal Communications Service. (a) Out of band emissions. The power of any emission outside of the authorized operating frequency ranges must be attenuated below the transmitting power (P) by a factor of at least 43 + 10 log(P) dB. (b) Measurement procedure. Compliance with these rules is based on...

47 CFR 24.238 - Emission limitations for Broadband PCS equipment.

Code of Federal Regulations, 2014 CFR

2014-10-01

... Broadband Personal Communications Service. (a) Out of band emissions. The power of any emission outside of the authorized operating frequency ranges must be attenuated below the transmitting power (P) by a factor of at least 43 + 10 log(P) dB. (b) Measurement procedure. Compliance with these rules is based on...

47 CFR 24.238 - Emission limitations for Broadband PCS equipment.

Code of Federal Regulations, 2013 CFR

2013-10-01

... Broadband Personal Communications Service. (a) Out of band emissions. The power of any emission outside of the authorized operating frequency ranges must be attenuated below the transmitting power (P) by a factor of at least 43 + 10 log(P) dB. (b) Measurement procedure. Compliance with these rules is based on...

75 FR 49870 - Effects on Broadband Communications Networks of Damage to or Failure of Network Equipment or...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-16

... FEDERAL COMMUNICATIONS COMMISSION 47 CFR Chapter I [PS Docket No. 10-92; DA 10-1357] Effects on Broadband Communications Networks of Damage to or Failure of Network Equipment or Severe Overload AGENCY: Federal Communications Commission ACTION: Proposed rule; extension of reply comment date. SUMMARY: This...

76 FR 62309 - Implementing a Nationwide, Broadband, Interoperable Public Safety Network in the 700 MHz Band

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-07

... FEDERAL COMMUNICATIONS COMMISSION 47 CFR Chapter I [PS Docket No. 06-229; WT Docket 06-150; WP Docket 07-100; FCC 11-113] Implementing a Nationwide, Broadband, Interoperable Public Safety Network in the 700 MHz Band AGENCY: Federal Communications Commission. ACTION: Final rule. SUMMARY: In this...

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

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-04

... FEDERAL COMMUNICATIONS COMMISSION 47 CFR Part 54 [WC Docket Nos. 11-42; 03-109; 12-23 and CC Docket No. 96-45; FCC 12- 11] Lifeline and Link Up Reform and Modernization, Advancing Broadband Availability Through Digital Literacy Training AGENCY: Federal Communications Commission. ACTION: Final rule...

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

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-01

... FEDERAL COMMUNICATIONS COMMISSION 47 CFR Part 54 [WC Docket Nos. 11-42, 03-109, 12-23 and CC Docket No. 96-45; FCC 12- 11] Lifeline and Link Up Reform and Modernization, Advancing Broadband Availability Through Digital Literacy Training AGENCY: Federal Communications Commission. ACTION: Final rule...

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

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-28

... FEDERAL COMMUNICATIONS COMMISSION 47 CFR Part 54 [WC Docket Nos. 11-42, 03-109, 12-23 and CC Docket No. 96-45; FCC 12- 11] Lifeline and Link Up Reform and Modernization, Advancing Broadband Availability Through Digital Literacy Training AGENCY: Federal Communications Commission. ACTION: Correcting...

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

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-30

... FEDERAL COMMUNICATIONS COMMISSION 47 CFR Part 54 [WC Docket Nos. 11-42, 03-109, 12-23 and CC Docket No. 96-45; FCC 12- 11] Lifeline and Link Up Reform and Modernization, Advancing Broadband Availability Through Digital Literacy Training AGENCY: Federal Communications Commission. ACTION: Final rule...

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

ERIC Educational Resources Information Center

Western Interstate Commission for Higher Education, 2009

2009-01-01

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

Wireless Broadband Communications Systems in Rural Wisconsin. Rural Research Report. Volume 19, Issue 1, Spring 2008

ERIC Educational Resources Information Center

Schlager, Kenneth J.

2008-01-01

This report describes a communications system engineering planning process that demonstrates an ability to design and deploy cost-effective broadband networks in low density rural areas. The emphasis in on innovative solutions and systems optimization because of the marginal nature of rural telecommunications infrastructure investments. Otherwise,…

The Importance of Distributed Broadband Networks to Academic Biomedical Research and Education Programs

ERIC Educational Resources Information Center

Yellowlees, Peter M.; Hogarth, Michael; Hilty, Donald M.

2006-01-01

Objective: This article highlights the importance of distributed broadband networks as part of the core infrastructure necessary to deliver academic research and education programs. Method: The authors review recent developments in the field and present the University of California, Davis, environment as a case study of a future virtual regional…

White-Light Optical Information Processing and Holography.

DTIC Science & Technology

1983-05-03

Processing, White-Light Holography, Image Subtraction, Image Deblurring , Coherence Requirement, Apparent Transfer Function, Source Encoding, Signal...in this period, also demonstrated several color image processing capabilities. Among those are broadband color image deblurring and color image...Broadband Image Deblurring ..... ......... 6 2.5 Color Image Subtraction ............... 7 2.6 Rainbow Holographic Aberrations . . ..... 7 2.7

Broadband Access for Students at East Tennessee State University

ERIC Educational Resources Information Center

Sawyer, Thomas Scott

2013-01-01

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

Rural Broadband at a Glance: 2009 Edition. Economic Information Bulletin Number 47

ERIC Educational Resources Information Center

US Department of Agriculture, 2009

2009-01-01

Three-quarters of U.S. residents used the Internet to access information, education, and services in 2007. Widespread Internet adoption suggests it has great value to individuals, businesses, and communities. Broadband Internet access is becoming essential for both businesses and households; many compare its evolution to other technologies now…

75 FR 55297 - Further Inquiry Into Two Under-Developed Issues in the Open Internet Proceeding

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-10

... facilities as broadband Internet access service (commonly called ``managed'' or ``specialized'' services). The second is the application of open Internet rules to mobile wireless Internet access services... Framework for Broadband Access to the Internet Over Wireline Facilities et al., CC Docket Nos. 02-33, 01-337...

Temporal characterization of small arms muzzle flash in the broadband visible

NASA Astrophysics Data System (ADS)

Burke, Tom; Bratlie, Duane

2010-04-01

The authors have developed a simple system for characterizing the muzzle flash duration of common military small-arms ammunition as a feeder for system design configurations. This paper is a synopsis of the efforts and results of the effort to characterize the broadband optical signature of modern small arms.

77 FR 22720 - Service Rules for Advanced Wireless Services in the 2000-2020 MHz and 2180-2200 MHz Bands, etc.

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-17

..., encourage innovation and investment in mobile broadband, and provide a stable regulatory environment in... of this spectrum, to encourage innovation and investment in mobile broadband, and to provide a stable... service, technical, assignment, and licensing rules for flexible terrestrial use of spectrum currently...

75 FR 36071 - Framework for Broadband Internet Service

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-24

... contractor, Best Copy and Printing, Inc. (BCPI), Portals II, 445 12th Street, SW., Room CY-B402, Washington...-leading high-speed broadband networks--both wired and wireless--lies at the very core of the FCC's mission... subscribers with high-speed Internet access, as well as many applications or functions that can be used with...

Methods and devices for generation of broadband pulsed radiation

DOEpatents

Borguet, Eric; Isaienko, Oleksandr

2013-05-14

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

Utilization of KSC Present Broadband Communications Data System For Digital Video Services

NASA Technical Reports Server (NTRS)

Andrawis, Alfred S.

2001-01-01

This report covers a visibility study of utilizing present KSC broadband communications data system (BCDS) for digital video services. Digital video services include compressed digital TV delivery and video-on-demand. Furthermore, the study examines the possibility of providing interactive video on demand to desktop personal computers via KSC computer network.

Hybrid silicon–carbon nanostructures for broadband optical absorption

DOE PAGES

Yang, Wen -Hua; Lu, Wen -Cai; Ho, K. M.; ...

2017-01-25

Proper design of nanomaterials for broadband light absorption is a key factor for improving the conversion efficiency of solar cells. Here we present a hybrid design of silicon–carbon nanostructures with silicon clusters coated by carbon cages, i.e., Si m@C 2n for potential solar cell application. The optical properties of these hybrid nanostructures were calculated based on time dependent density function theory (TDDFT). The results show that the optical spectra of Si m@C 2n are very different from those of pure Si m and C 2n clusters. While the absorption spectra of pure carbon cages and Si m clusters exhibit peaksmore » in the UV region, those of the Si m@C 2n nanostructures exhibit a significant red shift. Superposition of the optical spectra of various Si m@C 2n nanostructures forms a broad-band absorption, which extends to the visible light and infrared regions. As a result, the broadband adsorption of the assembled Si m@C 2n nanoclusters may provide a new approach for the design of high efficiency solar cell nanomaterials.« less

A One-Dimensional Organic Lead Chloride Hybrid with Excitation-Dependent Broadband Emissions

DOE PAGES

Wu, Guanhong; Zhou, Chenkun; Ming, Wenmei; ...

2018-05-23

Organic–inorganic metal halide hybrids have emerged as a new class of materials with fascinating optical and electronic properties. The exceptional structure tunability has enabled the development of materials with various dimensionalities at the molecular level, from three-dimensional (3D) to 2D, 1D, and 0D. Here, we report a new 1D lead chloride hybrid, C 4N 2H 14PbCl 4, which exhibits unusual inverse excitation-dependent broadband emission from bluish-green to yellow. Density functional theory calculations were performed to better understand the mechanism of this excitation-dependent broadband emission. This 1D hybrid material is found to have two emission centers, corresponding to the self-trapped excitonsmore » (STEs) and vacancy-bound excitons. The excitation-dependent emission is due to different populations of these two types of excitons generated at different excitation wavelengths. Furthermore, this work shows the rich chemistry and physics of organic–inorganic metal halide hybrids and paves the way to achieving novel light emitters with excitation-dependent broadband emissions at room temperature.« less

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

PubMed

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.

Detection and characterization of pulses in broadband seismometers

USGS Publications Warehouse

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

2017-01-01

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

Comparison of Simulated Contrast Performance of Different Phase Induced Amplitude Apodization (PIAA) Coronagraph Configurations

NASA Technical Reports Server (NTRS)

Sidick, Erkin; Kern, Brian; Kuhnert, Andreas; Shaklan, Stuart

2013-01-01

We compare the broadband contrast performances of several Phase Induced Amplitude Apodization (PIAA) coronagraph configurations through modeling and simulations. The basic optical design of the PIAA coronagraph is the same as NASA's High Contrast Imaging Testbed (HCIT) setup at the Jet Propulsion Laboratory (JPL). Using a deformable mirror and a broadband wavefront sensing and control algorithm, we create a "dark hole" in the broadband point-spread function (PSF) with an inner working angle (IWA) of 2(f lambda/D)(sub sky). We evaluate two systems in parallel. One is a perfect system having a design PIAA output amplitude and not having any wavefront error at its exit-pupil. The other is a realistic system having a design PIAA output amplitude and the measured residual wavefront error. We also investigate the effect of Lyot stops of various sizes when a postapodizer is and is not present. Our simulations show that the best 7.5%-broadband contrast value achievable with the current PIAA coronagraph is approximately 1.5x10(exp -8).