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Sample records for antenna architectures based

  1. DSN Antenna Array Architectures Based on Future NASA Mission Needs

    NASA Technical Reports Server (NTRS)

    MacNeal, Bruce E.; Abraham, Douglas S.; Cesarone, Robert J.

    2007-01-01

    A flexible method of parametric, full life-cycle cost analysis has been combined with data on NASA's future communication needs to estimate the required number and operational dates of new antennas for the Deep Space Network (DSN). The requirements were derived from a subset of missions in the Integrated Mission Set database of NASA's Space Communications Architecture Working Group. Assuming that no new antennas are 'constructed', the simulation shows that the DSN is unlikely to meet more than 20% of mission requirements by 2030. Minimum full life-cycle costs result when antennas in the diameter range, 18m-34m, are constructed. Architectures using a mixture of antenna diameters produce a slightly lower full life-cycle cost.

  2. Phased Array-Fed Reflector (PAFR) Antenna Architectures for Space-Based Sensors

    NASA Technical Reports Server (NTRS)

    Cooley, Michael E.

    2014-01-01

    Communication link and target ranges for satellite communications (SATCOM) and space-based sensors (e.g. radars) vary from approximately 1000 km (for LEO satellites) to 35,800 km (for GEO satellites). At these long ranges, large antenna gains are required and legacy payloads have usually employed large reflectors with single beams that are either fixed or mechanically steered. For many applications, there are inherent limitations that are associated with the use of these legacy antennas/payloads. Hybrid antenna designs using Phased Array Fed Reflectors (PAFRs) provide a compromise between reflectors and Direct Radiating phased Arrays (DRAs). PAFRs provide many of the performance benefits of DRAs while utilizing much smaller, lower cost (feed) arrays. The primary limitation associated with hybrid PAFR architectures is electronic scan range; approximately +/-5 to +/- 10 degrees is typical, but this range depends on many factors. For LEO applications, the earth FOV is approximately +/-55 degrees which is well beyond the range of electronic scanning for PAFRs. However, for some LEO missions, limited scanning is sufficient or the CONOPS and space vehicle designs can be developed to incorporate a combination mechanical slewing and electronic scanning. In this paper, we review, compare and contrast various PAFR architectures with a focus on their general applicability to space missions. We compare the RF performance of various PAFR architectures and describe key hardware design and implementation trades. Space-based PAFR designs are highly multi-disciplinary and we briefly address key hardware engineering design areas. Finally, we briefly describe two PAFR antenna architectures that have been developed at Northrop Grumman.

  3. Architectural study of active membrane antennas

    NASA Technical Reports Server (NTRS)

    Moussessian, A.; DiDomenico, L.; Edelstein, W.

    2002-01-01

    One method to dramatically reduce the weight, volume and associated cost of space-based SyntheticAperture Radars (SAR) is to replace the conventional rigid manifold antenna architecture with a flexible thin-film membrane. This has been successfully demonstrated as a passive array. To further reduce the cost and weight and provide 2D scanning required by space-based applications we also need to integrate the Transmit/Receive (TR) function into the inflatable antenna elements. This paper explores the constraints that must be placed on the active electronics of a flexible antenna array as well as some of the preliminary work in this area.

  4. Architectural design of a ground-based deep-space optical reception antenna

    NASA Technical Reports Server (NTRS)

    Kerr, E. L.

    1989-01-01

    An architectural design of a ground-based antenna (telescope) for receiving optical communications from deep space is presented. Physical and optical parameters, and their effect on the performance and cost considerations, are described. The channel capacity of the antenna is 100 kbits/s from Saturn and 5 Mbits/s from Mars. A novel sunshade is designed to permit optical communication even when the deep-space laser source is as close to the sun as 12 deg. Inserts in the tubes of the sunshade permit operations at solar elongations as small as 6 or 3 deg. The Nd:YAG source laser and the Fraunhofer filter (a narrow-band predetection optical filter) are tuned to match the Doppler shifts of the source and background. A typical Saturn-to-earth data link can reduce its source power requirement from 8.2 W to 2 W of laser output by employing a Fraunhofer filter instead of a conventional multilayer dielectric filter.

  5. Architectural design of a ground-based deep-space optical reception antenna

    NASA Technical Reports Server (NTRS)

    Kerr, E. L.

    1989-01-01

    An architectural design of a ground-based antenna (telescope) for receiving optical communications from deep space is presented. Physical and optical parameters, and their effect on the performance and cost considerations, are described. The channel capacity of the antenna is 100 kbits/s from Saturn and 5 Mbits/s from Mars. A novel sunshade is designed to permit optical communication even when the deep-space laser source is as close to the sun as 12 deg. Inserts in the tubes of the sunshade permit operations at solar elongations as small as 6 or 3 deg. The Nd:YAG source laser and the Fraunhofer filter (a narrow-band predetection optical filter) are tuned to match the Doppler shifts of the source and background. A typical Saturn-to-earth data link can reduce its source power requirement from 8.2 W to 2 W of laser output by employing a Fraunhofer filter instead of a conventional multilayer dielectric filter.

  6. On Antenna-Architectures for Sensitive Radiometry to Support Oceanography

    NASA Astrophysics Data System (ADS)

    Van't Klooster, Cornelis; Cappellin, Cecilia; Pontoppidan, Knud; Heighwood Nielsen, Per; Skou, Niels; Ivashina, Marianna; Iupikov, Oleg; Ihle, Alexander

    The presentation discusses different antenna architectures supporting radiometric tasks for oceanographic observations. With Aquarius and SMOS in orbit with their associated resolution and revisit capability in L-band, further enhancements are of interest. Following studies into desirable resolution and frequency band interests for oceanographic applications (ref: Microwat - an ESA study, see also https://www.ghrsst.org/ ), breaking through and desirable requirements have been derived. Investigations into potential antenna architectural realisations have been initiated. Included are radiometer sensor (read:antenna) scenarios, based on conical scanning, interferometric 1D and pushbroom coverage. A wide coverage is available from the first two architectures, and a very good sensitivity is available with the pushbroom scenario. There are a couple of interesting aspects, related to polarimetry capabilities, resolution, sensitivity, etc. The pushbroom architecture, at cost of some complexity offers a very good sensitivity with interesting antenna architecture solutions to offer breaking through capabilities, in particular concerning the sensitivity requirements, in combination with polarimetric capabilities. Coverage comes with some infrastructural antenna complexity, with the needs and creativity for a deployable antenna configuration. Following initial considerations for all three antenna configurations at overview level, the push-broom scenario is presented with more details. Interesting aspects include ongoing technology developments in other related fields with refined results to come would enable to consider antenna architectures are used in which focal plane arrays find a combination with shaped reflector assemblies. With processing capabilities further enhanced - with ongoing developments underway in other sectors as radio astronomers can confirm - one would be able to further improve and refine sensitivity aspects in combination with polarimetric capabilities

  7. Antenna selection in a SIMO architecture for HF radio links

    NASA Astrophysics Data System (ADS)

    Erhel, Yvon; Lemur, Dominique; Oger, Martial; Le Masson, Jérôme

    2016-03-01

    This work takes place in the global design of a SIMO architecture (single input multiple output) for transhorizon radio links, aiming at a significant increase in the data rate when compared with standard modems based in general on a SISO scheme (single input single output). The project is subject to available space constraints at the receive end, involving mobile stations or onboard implementation. We consider solutions that appear as extensions of the compact and heterogeneous antenna array that we proposed previously: collocated antennas of different types are set up with the same phase center and present diversity in their polarization sensitivities to make array processing effective. Given the number NC of receive channels, we address the problem of selecting the most effective antennas in a set of NA possible candidates including monopoles, dipoles, loop antennas with various geometries, and orientations. The criterion to be maximized is the SIMO outage capacity, a quantity based on the statistical distribution of the SIMO Shannon capacity estimated for a large number of ionospheric channel realizations, each of them being quantified by its channel impulse response including the receive antenna directional responses. Results are presented in the context of a 1 × 2 SIMO structure: the identification of the two most effective antennas in a set of NA = 15 sensors indicates that the optimal structures involve two orthogonal horizontal dipoles or two vertical orthogonal loop antennas. In these conditions, the outage capacity reaches up to 2.23 bps/Hz, a value that significantly exceeds the performances of standard modems.

  8. Single Front-End MIMO Architecture with Parasitic Antenna Elements

    NASA Astrophysics Data System (ADS)

    Yoshida, Mitsuteru; Sakaguchi, Kei; Araki, Kiyomichi

    In recent years, wireless communication technology has been studied intensively. In particular, MIMO which employs several transmit and receive antennas is a key technology for enhancing spectral efficiency. However, conventional MIMO architectures require some transceiver circuits for the sake of transmitting and receiving separate signals, which incurs the cost of one RF front-end per antenna. In addition to that, MIMO systems are assumed to be used in low spatial correlation environment between antennas. Since a short distance between each antenna causes high spatial correlation and coupling effect, it is difficult to miniaturize wireless terminals for mobile use. This paper shows a novel architecture which enables mobile terminals to be miniaturized and to work with a single RF front-end by means of adaptive analog beam-forming with parasitic antenna elements and antenna switching for spatial multiplexing. Furthermore, statistical analysis of the proposed architecture is also discussed in this paper.

  9. RF MEMS Based Reconfigurable Antennas

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.

    2004-01-01

    The presentation will first of all address the advantages of RF MEMS circuit in antenna applications and also the need for electronically reconfigurable antennas. Next, discuss some of the recent examples of RF MEMS based reconfigurable microstrip antennas. Finally, conclude the talk with a summary of MEMS antenna performance.

  10. An Intelligent Fault Detection and Isolation Architecture for Antenna Arrays

    NASA Astrophysics Data System (ADS)

    Rahnamai, K.; Arabshahi, P.; Yan, T.-Y.; Pham, T.; Finley, S. G.

    1997-10-01

    This article describes a general architecture for fault modeling, diagnosis, and isolation of the DSN antenna array based on computationally intelligent techniques(neural networks and fuzzy logic). It encompasses a suite of intelligent test and diagnosis algorithms in software. By continuously monitoring the health of the highly complex and nonlinear array observables, the automated diagnosis software will be able to identify and isolate the most likely causes of system failure in cases of faulty operation. Furthermore, it will be able to recommend a series of corresponding corrective actions and effectively act as an automated real-time and interactive system supervisor. In so doing, it will enhance the array capability by reducing the operational workload, increasing science information availability, reducing the overall cost of operation by reducing system downtimes, improving risk management, and making mission planning much more reliable. Operation of this architecture is illustrated using examples from observables available from the 34-meter arraying task.

  11. Affordable Wideband Multifunction Phased Array Antenna Architectures Using Frequency Scaled Radiating Elements

    DTIC Science & Technology

    2014-09-04

    Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/5310--14-9431 Affordable Wideband Multifunction Phased Array Antenna Architectures Using...Wideband Multifunction Phased Array Antenna Architectures Using Frequency Scaled Radiating Elements Rashmi Mital, Dharmesh P. Patel, Jaganmohan B.L. Rao...number of antennas on ships to meet the numerous functional requirements. Recently, wideband phased array antennas are being developed that can

  12. SIW Based Wideband Horn Antenna

    NASA Astrophysics Data System (ADS)

    Patel, Amit, Dr.; Vala, Alpesh; Goswami, Riddhi; Mahant, Keyur

    2017-08-01

    In this paper, we have proposed CSRR (complementary split ring resonator) loaded Substrate Integrated Waveguide (SIW) horn antenna. The whole system is designed on a single substrate, having advantages of small size, low profile, and low cost, etc. The design process and simulation results of a CSRR-loaded SIW horn antenna at K-band and Ka-band are presented. The proposed antenna is an outstanding choice for K, Ka bands and even higher frequency synthesis. It has well-behaved gain and suitable reflection coefficient value less than 1.5 (-10dB S11 and VSWR<1.5). The simulated gain of antenna attains 7.48±1dB over majority of the bandwidth and with radiation efficiency of 85%. The simulation has been done using full-wave package, High Frequency Structure Simulator Software (HFSS) based on Finite element method (FEM).

  13. Mark 4A antenna control system data handling architecture study

    NASA Technical Reports Server (NTRS)

    Briggs, H. C.; Eldred, D. B.

    1991-01-01

    A high-level review was conducted to provide an analysis of the existing architecture used to handle data and implement control algorithms for NASA's Deep Space Network (DSN) antennas and to make system-level recommendations for improving this architecture so that the DSN antennas can support the ever-tightening requirements of the next decade and beyond. It was found that the existing system is seriously overloaded, with processor utilization approaching 100 percent. A number of factors contribute to this overloading, including dated hardware, inefficient software, and a message-passing strategy that depends on serial connections between machines. At the same time, the system has shortcomings and idiosyncrasies that require extensive human intervention. A custom operating system kernel and an obscure programming language exacerbate the problems and should be modernized. A new architecture is presented that addresses these and other issues. Key features of the new architecture include a simplified message passing hierarchy that utilizes a high-speed local area network, redesign of particular processing function algorithms, consolidation of functions, and implementation of the architecture in modern hardware and software using mainstream computer languages and operating systems. The system would also allow incremental hardware improvements as better and faster hardware for such systems becomes available, and costs could potentially be low enough that redundancy would be provided economically. Such a system could support DSN requirements for the foreseeable future, though thorough consideration must be given to hard computational requirements, porting existing software functionality to the new system, and issues of fault tolerance and recovery.

  14. Developing an integrated photonic system with a simple beamforming architecture for phased-array antennas.

    PubMed

    Zhou, Weimin; Stead, Michael; Weiss, Steven; Okusaga, Olukayode; Jiang, Lingjun; Anderson, Stephen; Rena Huang, Z

    2017-01-20

    We have designed a simplified true-time-delay beamforming architecture using integrated photonics for phased-array antennas. This architecture can independently control multiple RF beams simultaneously with only a single tuning parameter to steer the beam in each direction for each beam. We have made a proof-of-the-principle demonstration of an X-band, 30×4-elements, fiber-optics-based beamformer for one-dimensional steering in transmission mode. The goal is to develop a semiconductor-based integrated photonic circuit so that a 2D beamforming array for both transmit and receive operations can be made on a single chip. For that, we have designed a Si-based integrated waveguide circuit using two types of "slow-light" waveguide for tunable time delays for two-dimensional steering.

  15. Wideband Patch Antenna for Land based Vehicles

    NASA Astrophysics Data System (ADS)

    Gangwar, R. P. S.; Dutt, Sanjay

    2016-12-01

    In this paper, an irregular pentagon shaped patch antenna has been presented. The proposed antenna operates over a wide band in frequency range from 12 to 26 GHz with VSWR < 2. It has a partial ground plane with two-inverted L and one I shaped slots in the radiation patch to attain wide bandwidth. The antenna consists of FR4 epoxy as a dielectric substrate with dielectric constant 4.4 and loss tangent 0.002. The size of the antenna is 30 × 30 × 1.57 mm3 and is fed by the microstrip line. The size of the fabricated proposed antenna is smaller than that of the antenna under reference (elliptical radiating patch with defected ground plane). The simulation has been done using high frequency structure simulator (HFSS) which is a finite element method (FEM) based tool. The proposed antenna exhibits the return loss of 21.85, 28.03 and 29.14 dB and gain of 6.6, 5.67 and 7.0 dB at resonant frequencies 16.7, 19.00 and 21.4 GHz, respectively. The bandwidth of the antenna is 10 GHz with normalized radiation efficiencies of 65, 69 and 70 % at corresponding resonant frequencies. The measured results of the fabricated proposed antenna have been compared with the simulated results and there has been a close agreement between both the results. Also the simulated results of the proposed antenna have been compared with the antenna under reference and it is found that the performance of the proposed antenna is far better. The proposed antenna can be used for land based vehicles in both Ku-band (12-18 GHz) and K-band (18-26 GHz).

  16. Metamaterial-based "sabre" antenna

    NASA Astrophysics Data System (ADS)

    Hafdallah Ouslimani, Habiba; Yuan, Tangjie; Kanane, Houcine; Priou, Alain; Collignon, Gérard; Lacotte, Guillaume

    2014-05-01

    The "sabre" antenna is an array of two monopole elements, vertically polarized with omnidirectional radiation patterns, and placed on either side of a composite material on the tail of an airplane. As an in-phase reflector plane, the antenna uses a compact dual-layer high-impedance surface (DL-HIS) with offset mushroom-like Sivenpiper square shape unit cells. This topology allows one to control both operational frequency and bandgap width, while reducing the total height of the antenna to under λ0/36. The designed antenna structure has a wide bandwidth higher than 24% around 1.4 GHz. The measurements and numerical simulations agree very well.

  17. Graphene-based optically transparent dipole antenna

    NASA Astrophysics Data System (ADS)

    Kosuga, Shohei; Suga, Ryosuke; Hashimoto, Osamu; Koh, Shinji

    2017-06-01

    We fabricated an optically transparent dipole antenna based on chemical vapor deposition (CVD)-grown monolayer graphene on an optically transparent quartz substrate and characterized its properties in microwave bands. The measurements of the reflection coefficients for the dipole antenna revealed that ˜90% of the microwave power transmitted to the CVD monolayer graphene of the antenna element. By measuring transmission coefficients, we demonstrated that the graphene dipole antenna radiated microwave power around the operational frequency (˜20.7 GHz). The operational frequency of the graphene dipole antenna (˜20.7 GHz) shifted to a higher frequency than that of the Au dipole antenna with the same structure (˜9.2 GHz), which suggests that monolayer graphene behaves not as a metal but as a dielectric material.

  18. Optical antenna of comb-shaped split ring architecture for increased field localization in NIR and MIR.

    PubMed

    Kilic, Veli Tayfun; Erturk, Vakur B; Demir, Hilmi Volkan

    2013-12-02

    We propose and demonstrate novel designs of optical antennas based on comb-shaped split ring architecture that display multi resonance field intensity enhancement spectrum. These nanoantennas achieve substantially increased field localization at longer wavelengths than that of a single or an array of dipoles with the same side length. With these optical antennas, localizing near infrared (NIR) and mid infrared (MIR) lights within a region of tens of nanometers at an intensity enhancement level of the order of thousands of magnitude can be accomplished.

  19. Tunable nano dispersed LC based patch antenna

    NASA Astrophysics Data System (ADS)

    Karim, Afaque; Yadav, Harsh; Ahmad, Shakeb

    2015-06-01

    This paper presents Patch antenna based on pure and Nano dispersed liquid crystals (LCs) for earth and space applications. Patch antenna are one of the most attractive antennas designed for RF frequency. To fulfill the demand of modern antenna i.e. tunability, a design of LC based patch antenna with optimum frequency of 15 GHz is investigated. In this design, NLC and ZnO doped NLC were used as a dielectric substrate. Its dielectric permittivity was controlled by biasing voltage. The dielectric properties of the 4-Cyano-4' -pentylbiphenyl (5CB) nematic liquid crystal (NLC), and NLC doped with Zinc oxide (ZnO) Nanoparticles was studied at room temperature. The concentration of doping material was 0.5% by w.t. in ZnO. Results shows that dielectric parameters are strong function of frequency and applied bias voltage. Moreover, Using doped NLC as dielectric substrate one gets more tunability or shift in resonant frequency in the proposed geometry.

  20. Smart antennas based on graphene

    SciTech Connect

    Aldrigo, Martino; Dragoman, Mircea; Dragoman, Daniela

    2014-09-21

    We report two configurations of smart graphene antennas, in which either the radiation pattern of the antenna or the backscattering of the periodic metallic arrays is controlled by DC biases that induce metal-insulator reversible transitions of graphene monolayers. Such a transition from a high surface resistance (no bias) to a low surface resistance state (finite bias voltage) causes the radiation pattern of metallic antennas backed with graphene to change dramatically, from omnidirectional to broadside. Moreover, reflectarrays enhance the backscattered field due to the same metal-dielectric transition.

  1. Lower-cost architectures for large arays of small antennas

    NASA Technical Reports Server (NTRS)

    Jones, Dayton L.

    2006-01-01

    Future plans for NASA's Deep Space Network (DSN) call for the construction of arrays of small antennas to compliment and eventually replace the existing network of large single antennas. The motivation for this transformation is the need to support much higher downlink data rates in the future, along with the realization that the most cost-effective way to do this is though a large increase in total collecting area on the ground. As currently designed, the DSN arrays will consist of approximately four hundred 12-m diameter antennas at each of three longitudes, operating at X and Ka bands (8 and 32 GHz).

  2. A New Blind Adaptive Array Antenna Based on CMA Criteria for M-Ary/SS Signals Suitable for Software Defined Radio Architecture

    NASA Astrophysics Data System (ADS)

    Kozuma, Miho; Sasaki, Atsushi; Kamiya, Yukihiro; Fujii, Takeo; Umebayashi, Kenta; Suzuki, Yasuo

    M-ary/SS is a version of Direct Sequence/Spread Spectrum (DS/SS) aiming to improve the spectral efficiency employing orthogonal codes. However, due to the auto-correlation property of the orthogonal codes, it is impossible to detect the symbol timing by observing correlator outputs. Therefore, conventionally, a preamble has been inserted in M-ary/SS, signals. In this paper, we propose a new blind adaptive array antenna for M-ary/SS systems that combines signals over the space axis without any preambles. It is surely an innovative approach for M-ary/SS. The performance is investigated through computer simulations.

  3. Detail of base of monopole antenna element with graduated pole, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail of base of monopole antenna element with graduated pole, view facing north - U.S. Naval Base, Pearl Harbor, Naval Radio Station, AF/FRD-10 Circularly Disposed Antenna Array, Wahiawa, Honolulu County, HI

  4. Large deployable antenna program. Phase 1: Technology assessment and mission architecture

    NASA Technical Reports Server (NTRS)

    Rogers, Craig A.; Stutzman, Warren L.

    1991-01-01

    The program was initiated to investigate the availability of critical large deployable antenna technologies which would enable microwave remote sensing missions from geostationary orbits as required for Mission to Planet Earth. Program goals for the large antenna were: 40-meter diameter, offset-fed paraboloid, and surface precision of 0.1 mm rms. Phase 1 goals were: to review the state-of-the-art for large, precise, wide-scanning radiometers up to 60 GHz; to assess critical technologies necessary for selected concepts; to develop mission architecture for these concepts; and to evaluate generic technologies to support the large deployable reflectors necessary for these missions. Selected results of the study show that deployable reflectors using furlable segments are limited by surface precision goals to 12 meters in diameter, current launch vehicles can place in geostationary only a 20-meter class antenna, and conceptual designs using stiff reflectors are possible with areal densities of 2.4 deg/sq m.

  5. Shear sensing based on a microstrip patch antenna

    NASA Astrophysics Data System (ADS)

    Mohammad, I.; Huang, H.

    2012-10-01

    A microstrip patch antenna sensor was studied for shear sensing with a targeted application of measuring plantar shear distribution on a diabetic foot. The antenna shear sensor consists of three components, namely an antenna patch, a soft foam substrate and a slotted ground plane. The resonant frequency of the antenna sensor is sensitive to the overlapping length between the slot in the ground plane and the antenna patch. A shear force applied along the direction of the slot deforms the foam substrate and causes a change in the overlapping length, which can be detected from the antenna frequency shift. The antenna shear sensor was designed based on simulated antenna frequency response and validated by experiments. Experimental results indicated that the antenna sensor exhibits high sensitivity to shear deformation and responds to the applied shear loads with excellent linearity and repeatability.

  6. Three-dimensional study of planar optical antennas made of split-ring architecture outperforming dipole antennas for increased field localization.

    PubMed

    Kilic, Veli Tayfun; Erturk, Vakur B; Demir, Hilmi Volkan

    2012-01-15

    Optical antennas are of fundamental importance for the strongly localizing field beyond the diffraction limit. We report that planar optical antennas made of split-ring architecture are numerically found in three-dimensional simulations to outperform dipole antennas for the enhancement of localized field intensity inside their gap regions. The computational results (finite-difference time-domain) indicate that the resulting field localization, which is of the order of many thousandfold, in the case of the split-ring resonators is at least 2 times stronger than the one in the dipole antennas resonant at the same operating wavelength, while the two antenna types feature the same gap size and tip sharpness.

  7. Microelectromechanical Systems Actuator Based Reconfigurable Printed Antenna

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N. (Inventor)

    2005-01-01

    A polarization reconfigurable patch antenna is disclosed. The antenna includes a feed element, a patch antenna element electrically connected to the feed element, and at least one microelectromechanical systems (MEMS) actuator, with a partial connection to the patch antenna element along an edge of the patch antenna element. The polarization of the antenna can be switched between circular polarization and linear polarization through action of the at least one MEMS actuator.

  8. A tunable microwave slot antenna based on graphene

    SciTech Connect

    Dragoman, Mircea; Aldrigo, Martino; Vasilache, D.; Dinescu, A.; Neculoiu, Dan; Bunea, Alina-Cristina; Deligeorgis, George; Konstantinidis, George; Mencarelli, Davide; Pierantoni, Luca; Modreanu, M.

    2015-04-13

    The paper presents the experimental and modeling results of a microwave slot antenna in a coplanar configuration based on graphene. The antennas are fabricated on a 4 in. high-resistivity Si wafer, with a ∼300 nm SiO{sub 2} layer grown through thermal oxidation. A CVD grown graphene layer is transferred on the SiO{sub 2}. The paper shows that the reflection parameter of the antenna can be tuned by a DC voltage. 2D radiation patterns at various frequencies in the X band (8–12 GHz) are then presented using as antenna backside a microwave absorbent and a metalized surface. Although the radiation efficiency is lower than a metallic antenna, the graphene antenna is a wideband antenna while the metal antennas with the same geometry and working at the same frequencies are narrowband.

  9. Integrated resonant tunneling diode based antenna

    DOEpatents

    Hietala, Vincent M.; Tiggers, Chris P.; Plut, Thomas A.

    2000-01-01

    An antenna comprising a plurality of negative resistance devices and a method for making same comprising employing a removable standoff layer to form the gap between the microstrip antenna metal and the bottom contact layer.

  10. Antenna unit and radio base station therewith

    DOEpatents

    Kuwahara, Mikio; Doi, Nobukazu; Suzuki, Toshiro; Ishida, Yuji; Inoue, Takashi; Niida, Sumaru

    2007-04-10

    Phase and amplitude deviations, which are generated, for example, by cables connecting an array antenna of a CDMA base station and the base station, are calibrated in the baseband. The base station comprises: an antenna apparatus 1; couplers 2; an RF unit 3 that converts a receive signal to a baseband signal, converts a transmit signal to a radio frequency, and performs power control; an A/D converter 4 for converting a receive signal to a digital signal; a receive beam form unit 6 that multiplies the receive signal by semi-fixed weight; a despreader 7 for this signal input; a time-space demodulator 8 for demodulating user data; a despreader 9 for probe signal; a space modulator 14 for user data; a spreader 13 for user signal; a channel combiner 12; a Tx calibrater 11 for controlling calibration of a signal; a D/A converter 10; a unit 16 for calculation of correlation matrix for generating a probe signal used for controlling an Rx calibration system and a TX calibration system; a spreader 17 for probe signal; a power control unit 18; a D/A converter 19; an RF unit 20 for probe signal; an A/D converter 21 for signal from the couplers 2; and a despreader 22.

  11. Detail of the base of dipole antenna element with graduated ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail of the base of dipole antenna element with graduated pole, note the arms supporting the vertical wires away from the mast and the metal mesh covering the concrete base, view facing west - U.S. Naval Base, Pearl Harbor, Naval Radio Station, AF/FRD-10 Circularly Disposed Antenna Array, Wahiawa, Honolulu County, HI

  12. A frequency reconfigurable antenna based on digital microfluidics.

    PubMed

    Damgaci, Yasin; Cetiner, Bedri A

    2013-08-07

    We present a novel antenna reconfiguration mechanism relying on electrowetting based digital microfluidics to implement a frequency reconfigurable antenna operating in the X-band. The antenna built on a quartz substrate (εr = 3.9, tan δ = 0.0002) is a coplanar waveguide fed annular slot antenna, which is monolithically integrated with a microfluidic chip. This chip establishes an electrowetting on dielectric platform with a mercury droplet placed in it. The base contact area of the mercury droplet can be spread out by electrostatic actuation resulting in a change of loading capacitance. This in turn changes the resonant frequency of the antenna enabling a reversible reconfigurable impedance property. This reconfigurable antenna has been designed, fabricated and measured. The frequency of operation is tuned from around 11 GHz to 13 GHz as demonstrated by simulations and measurements. The design methodology, fabrication processes and the experimental results are given and discussed.

  13. 8. VIEW OF THE EAST BASE CONNECTION OF ANTENNA TOWER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. VIEW OF THE EAST BASE CONNECTION OF ANTENNA TOWER S-111 FACING NORTHEAST. BUILDING 1 AND ANTENNA TOWER S-110 IN THE BACKGROUND. - U.S. Naval Base, Pearl Harbor, Lualualei Radio Transmitter, Edison & Tower Drives, Pearl City, Honolulu County, HI

  14. Low-profile metamaterial-based L-band antennas

    NASA Astrophysics Data System (ADS)

    Burokur, Shah Nawaz; Lepage, Anne-Claire; Varault, Stefan; Begaud, Xavier; Piau, Gérard-Pascal; de Lustrac, André

    2016-04-01

    The aim of the present contribution is to show that metasurfaces such as reactive impedance surfaces (RIS) and artificial magnetic conductors can be efficiently used in the design of low-profile circularly polarized L-band antennas. We present the design and simulation of the compact and low-profile antennas. The solution based on RIS will be compared to a circularly polarized microstrip patch antenna using the same materials in order to prove the benefit of metasurfaces. The engineered metasurfaces allow increasing the bandwidths with few modifications on the thickness and the overall antenna size.

  15. Antennae

    NASA Image and Video Library

    1999-12-09

    Atlas Image mosaic, covering 7 x 7 on the sky of the interacting galaxies NGC 4038 and NGC 4039, better known as the Antennae, or Ring Tail galaxies. The two galaxies are engaged in a tug-of-war as they collide.

  16. Simultaneous shear and pressure sensing based on patch antenna

    NASA Astrophysics Data System (ADS)

    Jiang, Hao; Huang, Haiying

    2015-04-01

    In this paper, we presented a microstrip patch antenna sensor that is capable to measure the shear and normal deformations simultaneously. The sensor was designed based on the electromagnetic interference between a microstrip patch antenna and a metallic reflector separated by a distance. By placing the reflector on top of the patch antenna, the electromagnetic wave radiated by the patch antenna is reflected by the reflector and interferes with the electromagnetic field of the radiation patch, which in turn changes the antenna resonant frequencies. Since the antenna resonant frequencies are related to the lateral and vertical positions of the metallic reflector, the shear force and normal pressure that shift the reflector laterally and vertically can be detected by monitoring the antenna resonant frequencies. The numerical simulation and experimental measurements were carried out to evaluate the relationship between the antenna resonant frequencies and the shear and normal displacements. A data processing scheme was developed to inversely determine the shear and normal displacements from the antenna resonant frequencies.

  17. Zeroth order resonator (ZOR) based RFID antenna design

    NASA Astrophysics Data System (ADS)

    Masud, Muhammad Mubeen

    Meander-line and multi-layer antennas have been used extensively to design compact UHF radio frequency identification (RFID) tags; however the overall size reduction of meander-line antennas is limited by the amount of parasitic inductance that can be introduced by each meander-line segment, and multi-layer antennas can be too costly. In this study, a new compact antenna topology for passive UHF RFID tags based on zeroth order resonant (ZOR) design techniques is presented. The antenna consists of lossy coplanar conductors and either inter-connected inter-digital capacitor (IDC) or shunt inductor unit-cells with a ZOR frequency near the operating frequency of the antenna. Setting the ZOR frequency near the operating frequency is a key component in the design process because the unit-cells chosen for the design are inductive at the operating frequency. This makes the unit-cells very useful for antenna miniaturization. These new designs in this work have several benefits: the coplanar layout can be printed on a single layer, matching inductive loops that reduce antenna efficiency are not required and ZOR analysis can be used for the design. Finally, for validation, prototype antennas are designed, fabricated and tested.

  18. Circularly split-ring-resonator-based frequency-reconfigurable antenna

    NASA Astrophysics Data System (ADS)

    Rahman, M. A.; Faruque, M. R. I.; Islam, M. T.

    2017-01-01

    In this paper, an antenna with frequency configurability in light of a circularly split-ring resonator (CSRR) is introduced. The proposed reconfigurable monopole antenna consists of a microstrip-fed hook-shaped structure and a CSRR having single reconfigurable split only. A new band of radiation unlike the band radiated from monopole only is observed due to magnetic coupling between the CSRR and the monopole antenna. The resonance frequency of the CSRR can be arbitrarily chosen by varying the dimension and relative position of its gap with the monopole, which leads the antenna to become reconfigurable one. By using a single switch with perfect electric conductor at the gap of CSRR cell, the effect of CSRR can be deactivated and, hence, it is possible to suppress the corresponding resonance, resulting in a frequency-reconfigurable antenna. Commercially available Computer Simulation Technology microwave studio based on finite integration technique was adopted throughout the study.

  19. Antennae

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Atlas Image mosaic, covering 7' x 7' on the sky of the interacting galaxies NGC 4038 and NGC 4039, better known as the Antennae, or Ring Tail galaxies. The two galaxies are engaged in a tug-of-war as they collide. The mutual gravitation between them is working to distort each spiral galaxy's appearance as the two merge. The interaction is evidently impetus for an intense burst of new star formation, as can be seen from the many infrared-bright knots and bright galactic nuclei. Compare the 2MASS view of this system with that obtained by the Hubble Space Telescope in the optical. Many of the same features are seen, although 2MASS is able to peer through much of the dust seen in the galaxies' disks. The galaxy light looks smoother. Also, in the near-infrared the bright knots of star formation are likely highlighted by the light of massive red supergiant stars. The much more extended 'tidal tails,' which give the Antennae their name, are quite faint in the 2MASS image mosaic.

  20. Reconfigurable water-substrate based antennas with temperature control

    NASA Astrophysics Data System (ADS)

    Mobashsher, Ahmed Toaha; Abbosh, Amin

    2017-06-01

    We report an unexplored reconfigurable antenna development technique utilizing the concept of temperature variable electromagnetic properties of water. By applying this physical phenomena, we present highly efficient water-substrate based antennas whose operating frequencies can be continuously tuned. While taking the advantage of cost-effectiveness of liquid water, this dynamic tuning technique also alleviates the roadblocks to widespread use of reconfigurable liquid-based antennas for VHF and UHF bands. The dynamic reconfigurability is controlled merely via external thermal stimulus and does not require any physical change of the resonating structure. We demonstrate dynamic control of omnidirectional and directional antennas covering more than 14 and 12% fractional bandwidths accordingly, with more than 85% radiation efficiency. Our temperature control approach paves the intriguing way of exploring dynamic reconfigurability of water-based compact electromagnetic devices for non-static, in-motion and low-cost real-world applications.

  1. Tunable antenna radome based on graphene frequency selective surface

    NASA Astrophysics Data System (ADS)

    Qu, Meijun; Rao, Menglou; Li, Shufang; Deng, Li

    2017-09-01

    In this paper, a graphene-based frequency selective surface (FSS) is proposed. The proposed FSS exhibits a tunable bandpass filtering characteristic due to the alterable conductivity of the graphene strips which is controlled by chemical potential. Based on the reconfigurable bandpass property of the proposed FSS, a cylindrical antenna radome is designed using the FSS unit cells. A conventional omnidirectional dipole can realize a two-beam directional pattern when it is placed into the proposed antenna radome. Forward and backward endfire radiations of the dipole loaded with the radome is realized by properly adjusting the chemical potential. The proposed antenna radome is extremely promising for beam-scanning in terahertz and mid-infrared plasmonic devices and systems when the gain of a conventional antenna needs to be enhanced.

  2. Space Elevator Base Leg Architecture

    NASA Astrophysics Data System (ADS)

    Swan, C.; Swan, P. A.

    While the Space Elevator stretches for 104,000 kilometers, the region of most concern, from the survival perspective, is 2,500 kms and below. The threats inside this dangerous arena include debris, spacecraft, meteorites, lightening, winds, rogue waves, aircraft, and intentional human acts. Two major questions will be addressed that will influence the overall systems architecture of a Space Elevator. While the deployment phase of the development of the Space Elevator will only have a single ribbon from the surface of the Earth to well beyond the Geosynchronous altitude, a mature Space Elevator must never allow a complete sever of the system. Design approaches, materials selections, international policy development and assembly must ensure that the integrity of the Space Elevator be maintained. The trade space analysis will address the probability of an individual ribbon being severed, the length of time to repair, and the potential for a catastrophic Space Elevator cut. The architecture proposed for the base leg portion will address two questions: Shall there be multiple base legs to 2,500 kms altitude? And Should the anchor be based on land or at sea?

  3. A 100 MHz antenna based on magnetoelectric composite materials

    NASA Astrophysics Data System (ADS)

    Tatarenko, A. S.; Petrov, R.; Srinivasan, G.; Bichurin, M. I.

    2008-03-01

    Results on miniaturization of a 100 MHz-antenna based on magnetoelectric composites are presented. A composite with large and equal permittivity and permeability is sought for the task. In such composites both miniaturization and impedance match to free-space are possible. A sample of nickel zinc ferrite and bismuth strontium titanate prepared by the conventional ceramic processing is used. The dipole antenna operating at 100 MHz consists of a composite substrate 220 mm in diameter and 8.5 mm in width and a Cu-strip 6.5 mm in diameter. Antenna characteristics are measured with a vector network analyzer. Scattering parameter data indicates resonance at 98 MHz and an antenna miniaturization factor of 7-10, in agreement with theoretical estimates.

  4. Architecture and System Engineering Development Study of Space-Based Satellite Networks for NASA Missions

    NASA Technical Reports Server (NTRS)

    Ivancic, William D.

    2003-01-01

    Traditional NASA missions, both near Earth and deep space, have been stovepipe in nature and point-to-point in architecture. Recently, NASA and others have conceptualized missions that required space-based networking. The notion of networks in space is a drastic shift in thinking and requires entirely new architectures, radio systems (antennas, modems, and media access), and possibly even new protocols. A full system engineering approach for some key mission architectures will occur that considers issues such as the science being performed, stationkeeping, antenna size, contact time, data rates, radio-link power requirements, media access techniques, and appropriate networking and transport protocols. This report highlights preliminary architecture concepts and key technologies that will be investigated.

  5. Reconfigurable architecture for MIMO systems based on CORDIC operators

    NASA Astrophysics Data System (ADS)

    Wang, Hongzhi; Leray, Pierre; Palicot, Jacques

    2006-09-01

    The MIMO system is an attractive technology for wireless 3G/4G systems. In this article we propose the realization on FPGA of a MIMO 'V-BLAST Square Root' algorithm based on a variable number of CORDIC operators. The CORDIC operator is highly suitable for this implementation as it only relies on simple techniques of addition and vector offsets. This square root algorithm architecture is reconfigurable in order to adapt itself to different numbers of antennas and different data rates. The proposed architecture can achieve a data rate of 600 Mbit/s in a Virtex-II FPGA circuit from Xilinx for the MIMO system with QPSK modulation. To cite this article: H. Wang et al., C. R. Physique 7 (2006).

  6. Study of mechanical architectures of large deployable space antenna apertures: from design to tests

    NASA Astrophysics Data System (ADS)

    Datashvili, L.; Endler, S.; Wei, B.; Baier, H.; Langer, H.; Friemel, M.; Tsignadze, N.; Santiago-Prowald, J.

    2013-12-01

    The technical assessment of large deployable reflector structures covering a diameter range from 4 to 50 m and RF frequencies up to Ka-Band is presented from the conceptual designs to the tests. Parametric FEM analysis tools of the concepts have been developed to study their static, modal and buckling behaviors. According to the selected conceptual design and acquired analysis results two complete breadboards with diameters of 1.6 m and 4 m based on a peripheral ring structure have been designed, manufactured and tested. Test results of both breadboards fulfilling the requirements on deployment repeatability and accuracy as well as scalability demonstrate the successful selection of a deployable ring design and large deployable antenna concept in whole.

  7. Antenna trajectory error analysis in backprojection-based SAR images

    NASA Astrophysics Data System (ADS)

    Wang, Ling; Yazıcı, Birsen; Yanik, H. Cagri

    2014-06-01

    We present an analysis of the positioning errors in Backprojection (BP)-based Synthetic Aperture Radar (SAR) images due to antenna trajectory errors for a monostatic SAR traversing a straight linear trajectory. Our analysis is developed using microlocal analysis, which can provide an explicit quantitative relationship between the trajectory error and the positioning error in BP-based SAR images. The analysis is applicable to arbitrary trajectory errors in the antenna and can be extended to arbitrary imaging geometries. We present numerical simulations to demonstrate our analysis.

  8. Entropy-based consistent model driven architecture

    NASA Astrophysics Data System (ADS)

    Niepostyn, Stanisław Jerzy

    2016-09-01

    A description of software architecture is a plan of the IT system construction, therefore any architecture gaps affect the overall success of an entire project. The definitions mostly describe software architecture as a set of views which are mutually unrelated, hence potentially inconsistent. Software architecture completeness is also often described in an ambiguous way. As a result most methods of IT systems building comprise many gaps and ambiguities, thus presenting obstacles for software building automation. In this article the consistency and completeness of software architecture are mathematically defined based on calculation of entropy of the architecture description. Following this approach, in this paper we also propose our method of automatic verification of consistency and completeness of the software architecture development method presented in our previous article as Consistent Model Driven Architecture (CMDA). The proposed FBS (Functionality-Behaviour-Structure) entropy-based metric applied in our CMDA approach enables IT architects to decide whether the modelling process is complete and consistent. With this metric, software architects could assess the readiness of undergoing modelling work for the start of IT system building. It even allows them to assess objectively whether the designed software architecture of the IT system could be implemented at all. The overall benefit of such an approach is that it facilitates the preparation of complete and consistent software architecture more effectively as well as it enables assessing and monitoring of the ongoing modelling development status. We demonstrate this with a few industry examples of IT system designs.

  9. Wireless OAM transmission system based on elliptical microstrip patch antenna.

    PubMed

    Chen, Jia Jia; Lu, Qian Nan; Dong, Fei Fei; Yang, Jing Jing; Huang, Ming

    2016-05-30

    The multiplexing transmission has always been a focus of attention for communication technology. In this paper, the radiation characteristics of circular microstrip patch antenna was firstly analyzed based on cavity model theory, and then spiral beams carrying orbital angular momentum (OAM) were generated, using elliptical microstrip patch antenna, with a single feed probe instead of a standard circular patch with two feedpoints. Moreover, by combining the proposed elliptic microstrip patch antenna with Universal Software Radio Peripheral (USRP), a wireless OAM transmission system was established and the real-time transmission of text, image and video in a real channel environment was realized. Since the wireless OAM transmission has the advantage of good safety and high spectrum utilization efficiency, this work has theoretical significance and potential application.

  10. New chiral cyclooctatriene-based polycyclic architectures.

    PubMed

    Pieters, Grégory; Gaucher, Anne; Marrot, Jérôme; Maurel, François; Naubron, Jean-Valère; Jean, Marion; Vanthuyne, Nicolas; Crassous, Jeanne; Prim, Damien

    2011-08-19

    The synthesis and properties of new chiral polycyclic architectures that display both helicity and a saddle-type shape are described. The enantiomers have been separated, and their absolute configuration was determined by VCD and ECD. The unprecedented molecular architecture is based on a cyclooctatriene core surrounded by an association of benzo[c]fluorene and ortho-phenylene units.

  11. Antenna Calibration and Measurement Equipment

    NASA Technical Reports Server (NTRS)

    Rochblatt, David J.; Cortes, Manuel Vazquez

    2012-01-01

    A document describes the Antenna Calibration & Measurement Equipment (ACME) system that will provide the Deep Space Network (DSN) with instrumentation enabling a trained RF engineer at each complex to perform antenna calibration measurements and to generate antenna calibration data. This data includes continuous-scan auto-bore-based data acquisition with all-sky data gathering in support of 4th order pointing model generation requirements. Other data includes antenna subreflector focus, system noise temperature and tipping curves, antenna efficiency, reports system linearity, and instrument calibration. The ACME system design is based on the on-the-fly (OTF) mapping technique and architecture. ACME has contributed to the improved RF performance of the DSN by approximately a factor of two. It improved the pointing performances of the DSN antennas and productivity of its personnel and calibration engineers.

  12. Multi-walled carbon nanotube-based RF antennas.

    PubMed

    Elwi, Taha A; Al-Rizzo, Hussain M; Rucker, Daniel G; Dervishi, Enkeleda; Li, Zhongrui; Biris, Alexandru S

    2010-01-29

    A novel application that utilizes conductive patches composed of purified multi-walled carbon nanotubes (MWCNTs) embedded in a sodium cholate composite thin film to create microstrip antennas operating in the microwave frequency regime is proposed. The MWCNTs are suspended in an adhesive solvent to form a conductive ink that is printed on flexible polymer substrates. The DC conductivity of the printed patches was measured by the four probe technique and the complex relative permittivity was measured by an Agilent E5071B probe. The commercial software package, CST Microwave Studio (MWS), was used to simulate the proposed antennas based on the measured constitutive parameters. An excellent agreement of less than 0.2% difference in resonant frequency is shown. Simulated and measured results were also compared against identical microstrip antennas that utilize copper conducting patches. The proposed MWCNT-based antennas demonstrate a 5.6% to 2.2% increase in bandwidth, with respect to their corresponding copper-based prototypes, without significant degradation in gain and/or far-field radiation patterns.

  13. Multi-walled carbon nanotube-based RF antennas

    NASA Astrophysics Data System (ADS)

    Elwi, Taha A.; Al-Rizzo, Hussain M.; Rucker, Daniel G.; Dervishi, Enkeleda; Li, Zhongrui; Biris, Alexandru S.

    2010-01-01

    A novel application that utilizes conductive patches composed of purified multi-walled carbon nanotubes (MWCNTs) embedded in a sodium cholate composite thin film to create microstrip antennas operating in the microwave frequency regime is proposed. The MWCNTs are suspended in an adhesive solvent to form a conductive ink that is printed on flexible polymer substrates. The DC conductivity of the printed patches was measured by the four probe technique and the complex relative permittivity was measured by an Agilent E5071B probe. The commercial software package, CST Microwave Studio (MWS), was used to simulate the proposed antennas based on the measured constitutive parameters. An excellent agreement of less than 0.2% difference in resonant frequency is shown. Simulated and measured results were also compared against identical microstrip antennas that utilize copper conducting patches. The proposed MWCNT-based antennas demonstrate a 5.6% to 2.2% increase in bandwidth, with respect to their corresponding copper-based prototypes, without significant degradation in gain and/or far-field radiation patterns.

  14. PATL: A RFID Tag Localization based on Phased Array Antenna

    PubMed Central

    Qiu, Lanxin; Liang, Xiaoxuan; Huang, Zhangqin

    2017-01-01

    In RFID systems, how to detect the position precisely is an important and challenging research topic. In this paper, we propose a range-free 2D tag localization method based on phased array antenna, called PATL. This method takes advantage of the adjustable radiation angle of the phased array antenna to scan the surveillance region in turns. By using the statistics of the tags’ number in different antenna beam directions, a weighting algorithm is used to calculate the position of the tag. This method can be applied to real-time location of multiple targets without usage of any reference tags or additional readers. Additionally, we present an optimized weighting method based on RSSI to increase the locating accuracy. We use a Commercial Off-the-Shelf (COTS) UHF RFID reader which is integrated with a phased array antenna to evaluate our method. The experiment results from an indoor office environment demonstrate the average distance error of PATL is about 21 cm and the optimized approach achieves an accuracy of 13 cm. This novel 2D localization scheme is a simple, yet promising, solution that is especially applicable to the smart shelf visualized management in storage or retail area. PMID:28295014

  15. PATL: A RFID Tag Localization based on Phased Array Antenna.

    PubMed

    Qiu, Lanxin; Liang, Xiaoxuan; Huang, Zhangqin

    2017-03-15

    In RFID systems, how to detect the position precisely is an important and challenging research topic. In this paper, we propose a range-free 2D tag localization method based on phased array antenna, called PATL. This method takes advantage of the adjustable radiation angle of the phased array antenna to scan the surveillance region in turns. By using the statistics of the tags' number in different antenna beam directions, a weighting algorithm is used to calculate the position of the tag. This method can be applied to real-time location of multiple targets without usage of any reference tags or additional readers. Additionally, we present an optimized weighting method based on RSSI to increase the locating accuracy. We use a Commercial Off-the-Shelf (COTS) UHF RFID reader which is integrated with a phased array antenna to evaluate our method. The experiment results from an indoor office environment demonstrate the average distance error of PATL is about 21 cm and the optimized approach achieves an accuracy of 13 cm. This novel 2D localization scheme is a simple, yet promising, solution that is especially applicable to the smart shelf visualized management in storage or retail area.

  16. Antenna modeling considerations for accurate SAR calculations in human phantoms in close proximity to GSM cellular base station antennas.

    PubMed

    van Wyk, Marnus J; Bingle, Marianne; Meyer, Frans J C

    2005-09-01

    International bodies such as International Commission on Non-Ionizing Radiation Protection (ICNIRP) and the Institute for Electrical and Electronic Engineering (IEEE) make provision for human exposure assessment based on SAR calculations (or measurements) and basic restrictions. In the case of base station exposure this is mostly applicable to occupational exposure scenarios in the very near field of these antennas where the conservative reference level criteria could be unnecessarily restrictive. This study presents a variety of critical aspects that need to be considered when calculating SAR in a human body close to a mobile phone base station antenna. A hybrid FEM/MoM technique is proposed as a suitable numerical method to obtain accurate results. The verification of the FEM/MoM implementation has been presented in a previous publication; the focus of this study is an investigation into the detail that must be included in a numerical model of the antenna, to accurately represent the real-world scenario. This is accomplished by comparing numerical results to measurements for a generic GSM base station antenna and appropriate, representative canonical and human phantoms. The results show that it is critical to take the disturbance effect of the human phantom (a large conductive body) on the base station antenna into account when the antenna-phantom spacing is less than 300 mm. For these small spacings, the antenna structure must be modeled in detail. The conclusion is that it is feasible to calculate, using the proposed techniques and methodology, accurate occupational compliance zones around base station antennas based on a SAR profile and basic restriction guidelines.

  17. Directional Antenna for Whistlers Based on Helicity Injection

    NASA Astrophysics Data System (ADS)

    Stenzel, R. L.; Urrutia, J. M.; Rousculp, C. L.

    1997-11-01

    In an unbounded uniform magnetoplasma, spatial whistler wave packets with ω_ci << ω << ω_ce have positive/negative helicity (int A \\cdot B dv; int J \\cdot B dv) for propagation along/against the background field B_0. An antenna which injects no helicity, e.g., a simple dipole, radiates equal wave packets along ±B0 which conserves net zero helicity. Vice versa, helicity injection produces asymmetric radiation patterns.(C. L. Rousculp and R. L. Stenzel, Phys. Rev. Lett., July 1997.) Based on this principle, a directional antenna has been built consisting of a field-aligned magnetic loop on the axis of a torus. The radiation properties have been measured in a large laboratory plasma. Positive helicity injection is observed to produce radiation along B_0, negative helicity injection radiates opposite to B_0, with good directionality (20 dB). Transmission between two identical antennas is unidirectional, hence non reciprocal. Possible applications of directional helicity antennas will be shown.

  18. Advances in Scanning Reflectarray Antennas Based on Ferroelectric Thin Film Phase Shifters for Deep Space Communications

    NASA Technical Reports Server (NTRS)

    Romanofsky, Robert R.

    2007-01-01

    Though there are a few examples of scanning phased array antennas that have flown successfully in space, the quest for low-cost, high-efficiency, large aperture microwave phased arrays continues. Fixed and mobile applications that may be part of a heterogeneous exploration communication architecture will benefit from the agile (rapid) beam steering and graceful degradation afforded by phased array antennas. The reflectarray promises greater efficiency and economy compared to directly-radiating varieties. Implementing a practical scanning version has proven elusive. The ferroelectric reflectarray, under development and described herein, involves phase shifters based on coupled microstrip patterned on Ba(x)Sr(1-x)TiO3 films, that were laser ablated onto LaAlO3 substrates. These devices outperform their semiconductor counterparts from X- through and K-band frequencies. There are special issues associated with the implementation of a scanning reflectarray antenna, especially one realized with thin film ferroelectric phase shifters. This paper will discuss these issues which include: relevance of phase shifter loss; modulo 2(pi) effects and phase shifter transient effects on bit error rate; scattering from the ground plane; presentation of a novel hybrid ferroelectric-semiconductor phase shifter; and the effect of mild radiation exposure on phase shifter performance.

  19. Antenna Technology for QUASAT application. [radio antenna for very long base interferometry missions

    NASA Technical Reports Server (NTRS)

    Archer, J. S.; Palmer, W. B.

    1985-01-01

    A hybrid growth version of the advanced Sunflower, or precision deployable, antenna was adopted as the configuration proposed for the QUASAT very long baseline interferometry mission. The antenna consists of rigid panels of graphite-epoxy facesheets covering aluminum honeycomb sandwich. The six main folding panels are hinged to a cantilevered support ring attached to the periphery of the center section. Six pairs of intermediate panels are located between these panels and are hinged to each other and to the main panels. The flight configuration, antenna weight, a mass properties, frequency, and contour tolerance are discussed. The advantages of the solid antenna surface cover an all-mesh contour are examined.

  20. Aerogel-Based Antennas for Aerospace and Terrestrial Applications

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann (Inventor); Miranda, Felix (Inventor); Van Keuls, Frederick (Inventor)

    2016-01-01

    Systems and methods for lightweight, customizable antenna with improved performance and mechanical properties are disclosed. In some aspects, aerogels can be used, for example, as a substrate for antenna fabrication. The reduced weight and expense, as well as the increased ability to adapt antenna designs, permits a systems to mitigate a variety of burdens associated with antennas while providing added benefits.

  1. An architecture for rule based system explanation

    NASA Technical Reports Server (NTRS)

    Fennel, T. R.; Johannes, James D.

    1990-01-01

    A system architecture is presented which incorporate both graphics and text into explanations provided by rule based expert systems. This architecture facilitates explanation of the knowledge base content, the control strategies employed by the system, and the conclusions made by the system. The suggested approach combines hypermedia and inference engine capabilities. Advantages include: closer integration of user interface, explanation system, and knowledge base; the ability to embed links to deeper knowledge underlying the compiled knowledge used in the knowledge base; and allowing for more direct control of explanation depth and duration by the user. User models are suggested to control the type, amount, and order of information presented.

  2. Options for a lunar base surface architecture

    NASA Technical Reports Server (NTRS)

    Roberts, Barney B.

    1991-01-01

    The analysis of the Space Exploration Initiative architectures involves making definitions of systems engineering designs for the construction of lunar and Mars bases for the support of science, exploration, and resource production on these planets. This paper discusses the results of the Space Resource Utilization Architecture study, which was initiated to develop the technical capability for extracting useful materials from the indigenous resources of the moon and Mars. For the moon, an infrastructure concept of a base is designed which can support a crew of 12. The major phases of the lunar-base development, the systems and the elements involved, and the physical layout and evolution of the base are described.

  3. 2-SR-based electrically small antenna for RFID applications

    NASA Astrophysics Data System (ADS)

    Paredes, Ferran; Zuffanelli, Simone; Aguilà, Pau; Zamora, Gerard; Martin, Ferran; Bonache, Jordi

    2016-04-01

    In this work, the 2-turn spiral resonator (2-SR) is proposed as an electrically small antenna for passive radio frequency identification (RFID) tags at the European ultra-high frequency (UHF) band. The radiation properties are studied in order to explore the viability of the 2-SR applied to tag antenna design. Based on analytical calculations, the radiation pattern is found to provide a cancelation of the radiation nulls. This results in a mitigation of the blind spots in the read range, which are present in typical UHF-RFID tags as an undesired feature. As a proof of concept, a passive tag of size 35 mm × 40 mm (λ 0/10 × λ 0/9) based on the 2-SR antenna is designed and fabricated. Good radiation efficiency (75 %) and a quasi-isotropic radiation pattern are obtained. The experimental tag read range for different directions is in good agreement with the simulation results. The measured read range exhibits maximum and minimum values of 6.7 and 3.5 m, respectively.

  4. ARCHITECTURE OF A CHARGE-TRANSFER STATE REGULATING LIGHT HARVESTING IN A PLANT ANTENNA PROTEIN

    SciTech Connect

    Fleming, Graham; Ahn, Tae Kyu; Avenson, Thomas J.; Ballottari, Matteo; Cheng, Yuan-Chung; Niyogi, Krishna K.; Bassi, Roberto; Fleming, Graham R.

    2008-04-02

    Energy-dependent quenching of excess absorbed light energy (qE) is a vital mechanism for regulating photosynthetic light harvesting in higher plants. All of the physiological characteristics of qE have been positively correlated with charge-transfer between coupled chlorophyll and zeaxanthin molecules in the light-harvesting antenna of photosystem II (PSII). In this work, we present evidence for charge-transfer quenching in all three of the individual minor antenna complexes of PSII (CP29, CP26, and CP24), and we conclude that charge-transfer quenching in CP29 involves a de-localized state of an excitonically coupled chlorophyll dimer. We propose that reversible conformational changes in CP29 can `tune? the electronic coupling between the chlorophylls in this dimer, thereby modulating the energy of the chlorophylls-zeaxanthin charge-transfer state and switching on and off the charge-transfer quenching during qE.

  5. An Architecture for Case-Based Learning

    ERIC Educational Resources Information Center

    Cifuentes, Laurent; Mercer, Rene; Alverez, Omar; Bettati, Riccardo

    2010-01-01

    We report on the design, development, implementation, and evaluation of a case-based instructional environment designed for learning network engineering skills for cybersecurity. We describe the societal problem addressed, the theory-based solution, and the preliminary testing and evaluation of that solution. We identify an architecture for…

  6. An Architecture for Case-Based Learning

    ERIC Educational Resources Information Center

    Cifuentes, Laurent; Mercer, Rene; Alverez, Omar; Bettati, Riccardo

    2010-01-01

    We report on the design, development, implementation, and evaluation of a case-based instructional environment designed for learning network engineering skills for cybersecurity. We describe the societal problem addressed, the theory-based solution, and the preliminary testing and evaluation of that solution. We identify an architecture for…

  7. Self-organizing control for space-based sparse antennas

    NASA Technical Reports Server (NTRS)

    Hadaegh, Fred Y.; Jamnejad, Vaharaz; Scharf, Daniel P.; Ploen, Scott R.

    2003-01-01

    An integrated control and electromagnetic/antenna formulation is presented for evaluating the performance of a distributed antenna system as a function of formation geometry. A distributed and self-organizing control law for the control law for the control of multiple antennas in Low Earth Orbit (LEO) is presented. The control system provides collaborative commanding and performance optimization to configure and operate the distributed formation system. A large aperture antenna is thereby realized by a collection of miniature sparse antennas in formation. A case study consisting of a simulation of four antennas in Low Earth orbit (LEO)is presented to demonstrate the concept.

  8. Tri-band small monopole antenna based on SRR units

    NASA Astrophysics Data System (ADS)

    Shehata, Gehan; Mohanna, Mahmoud; Rabeh, Mohammed Lotfy

    2015-12-01

    In this paper a novel design for a tri-band monopole antenna coupled with metamaterial units is introduced. The proposed antenna was designed to cover WiMAX (2.5, 3.5) and WLAN (5.2) bands. In our proposal, a coplanar waveguide (CPW) fed circular-disk monopole antenna is coupled with three split ring resonator (SRR) units which exist on its back side. In our design a monopole antenna and SRR units are designed first to resonate at 5.2 GHz and 2.5 GHz respectively. In addition, antenna is loaded with post to force resonance at 3.5 GHz. SRR units are used for 2.5 GHz resonance to miniaturize antenna size, and our proposed antenna considered an electrically small antenna (ESA) at its first resonance frequency. Simulated and measured results exhibit a good agreement that validate our design.

  9. Antenna pointing compensation based on precision optical measurement techniques

    NASA Technical Reports Server (NTRS)

    Schumacher, L. L.; Vivian, H. C.

    1988-01-01

    The pointing control loops of the Deep Space Network 70 meter antennas extend only to the Intermediate Reference Structure (IRS). Thus, distortion of the structure forward of the IRS due to unpredictable environmental loads can result in uncompensated boresight shifts which degrade blind pointing accuracy. A system is described which can provide real time bias commands to the pointing control system to compensate for environmental effects on blind pointing performance. The bias commands are computed in real time based on optical ranging measurements of the structure from the IRS to a number of selected points on the primary and secondary reflectors.

  10. Analysis of graphene based optically transparent patch antenna for terahertz communications

    NASA Astrophysics Data System (ADS)

    Thampy, Anand Sreekantan; Darak, Mayur Sudesh; Dhamodharan, Sriram Kumar

    2015-02-01

    With and without multi walled carbon nanotube (MWCNT) loaded graphene based optically transparent patch antennas are designed to resonate at 6 THz. Their radiation characteristics are analyzed in 5.66-6.43 THz band. The optically transparent graphene is deployed as the patch and ground plane of the antennas, which are separated by a 2.5 μm thick flexible polyimide substrate. By shorting the microstrip line and ground plane of the antenna with a MWCNT via, the return loss of the antenna is improved. The peak gain of 3.3dB at 6.2 THz and a gain greater than 3dB in 5.66-6.43 THz band is obtained for antenna loaded without MWCNT. Both the antennas achieved a -10dB impedance bandwidth of 12.83%. Gain, directivity and radiation efficiency of the proposed antennas are compared with conventional transparent patch antennas and graphene based non-transparent antennas. The antenna structures are simulated by using finite element method based electromagnetic simulator-Ansys HFSS.

  11. CHEM-Based Self-Deploying Spacecraft Radar Antennas

    NASA Technical Reports Server (NTRS)

    Sokolowski, Witold; Huang, John; Ghaffarian, Reza

    2004-01-01

    A document proposes self-deploying spacecraft radar antennas based on cold hibernated elastic memory (CHEM) structures. Described in a number of prior NASA Tech Briefs articles, the CHEM concept is one of utilizing open-cell shape-memory-polymer (SMP) foams to make lightweight structures that can be compressed for storage and can later be expanded, then rigidified for use. A CHEM-based antenna according to the proposal would comprise three layers of microstrip patches and transmission lines interspersed with two flat layers of SMP foam, which would serve as both dielectric spacers and as means of deployment. The SMP foam layers would be fabricated at full size at a temperature below the SMP glass-transition temperature (Tg). The layers would be assembled into a unitary structure, which, at temperature above Tg, would be compacted to much smaller thickness, then rolled up for storage. Next, the structure would be cooled to below Tg and kept there during launch. Upon reaching the assigned position in outer space, the structure would be heated above Tg to make it rebound to its original size and shape. The structure as thus deployed would then be rigidified by natural cooling to below Tg

  12. Analysis and design of terahertz antennas based on plasmonic resonant graphene sheets

    SciTech Connect

    Tamagnone, M.; Gomez-Diaz, J. S.; Perruisseau-Carrier, J.

    2012-12-01

    Resonant graphene antennas used as true interfaces between terahertz (THz) space waves and a source/detector are presented. It is shown that in addition to the high miniaturization related to the plasmonic nature of the resonance, graphene-based THz antenna favorably compare with typical metal implementations in terms of return loss and radiation efficiency. Graphene antennas will contribute to the development of miniature, efficient, and potentially transparent all-graphene THz transceivers for emerging communication and sensing application.

  13. An X-band parabolic antenna based on gradient metasurface

    SciTech Connect

    Yao, Wang; Yang, Helin Tian, Ying; Guo, Linyan; Huang, Xiaojun

    2016-07-15

    We present a novel parabolic antenna by employing reflection gradient metasurface which is composed of a series of circle patches on a grounded dielectric substrate. Similar to the traditional parabolic antenna, the proposed antenna take the metasurface as a “parabolic reflector” and a patch antenna was placed at the focal point of the metasurface as a feed source, then the quasi-spherical wave emitted by the source is reflected and transformed to plane wave with high efficiency. Due to the focus effect of reflection, the beam width of the antenna has been decreased from 85.9° to 13° and the gain has been increased from 6.5 dB to 20.8 dB. Simulation and measurement results of both near and far-field plots demonstrate good focusing properties of the proposed parabolic antenna.

  14. Distributed Antenna-Coupled Transition Edge Sensors

    NASA Technical Reports Server (NTRS)

    Day, Peter K.; LeDuc, Henry G.; Lee, Richard A. M.; Dowell, C. Darren; Zmuidzinas, Jonas

    2006-01-01

    We describe progress toward realizing a new architecture for focal plane arrays for the Submillimeter and Far- Infrared (FIR) bands. This architecture is based on a detector design utilizing distributed hot{electron transition edge sensors (TES) coupled to slot antenna elements. Arrays utilizing this type of detector can be considerably easier to manufacture than membrane-isolated TES arrays, because the need for micro-machining is eliminated. We present background and rationale for this new array architecture and details of a new antenna design for an imaging polarimeter, which yields greater bandwidth than past designs. In addition, we describe a cryogenic facility for testing these arrays.

  15. Dual-band microstrip patch antenna based on metamaterial refractive surface

    NASA Astrophysics Data System (ADS)

    Salhi, Ridha; Labidi, Mondher; Boujemaa, Mohamed Ali; Choubani, Fethi

    2017-06-01

    In this paper, we present a new design of microstrip patch antenna based on metamaterial refractive surface (MRS). By optimizing the air gap between the MRS layer and the patch antenna to be 7 mm, the band width and the gain of the proposed antenna are significantly enhanced. The proposed prototype presents a dual band antenna. The center frequency for the first band is 2.44 GHz and the generated bandwidth is 25 MHz. The second band has a center frequency of 2.8 GHz and with a bandwidth of 50 MHz. The simulation results are analyzed and discussed in terms of return loss, gain and radiation pattern using electromagnetic simulator software. Finally, the designed dual band antenna is fabricated and different measurement results are performed and compared with simulation results in order to validate its performances. The proposed antenna supports WiBro (wireless broadband), ISM, WiFi, Bluetooth, WiMAX and radars services.

  16. The Numerical Simulation of the Broadband Spiral Antenna Design Based on Hybrid Backed-Cavity

    NASA Astrophysics Data System (ADS)

    Liu, Chunheng; Lu, Yueguang; Du, Chunlei; Cui, Jingbo; Shen, Ximing

    2009-09-01

    In the paper, the hybrid backed-cavity with EBG (Electromagnetic Band-Gap) structure and PEC (Perfect Electronic Conductor) is proposed for Archimedean spiral antenna, which can make the spiral antenna work over the 10:1 bandwidth, without the loss introduced by absorbing materials. Based on the AMC characteristic (Artificial Magnetic Conductor), the EBG is placed in the outer region of backed-cavity to improve the blind spot gain in the low frequency. The PEC at the center of the structure is used to obtain high gain at high frequency. The better antenna performances are achieved in the low profile spiral antenna. A typical spiral antenna with hybrid backed cavity is numerically studied. The novel spiral antenna design with hybrid backed cavity is validated by simulated results.

  17. A Small Chloroplast-Encoded Protein as a Novel Architectural Component of the Light-Harvesting Antenna

    PubMed Central

    Ruf, Stephanie; Biehler, Klaus; Bock, Ralph

    2000-01-01

    A small conserved open reading frame in the plastid genome, ycf9, encodes a putative membrane protein of 62 amino acids. To determine the function of this reading frame we have constructed a knockout allele for targeted disruption of ycf9. This allele was introduced into the tobacco plastid genome by biolistic transformation to replace the wild-type ycf9 allele. Homoplasmic ycf9 knockout plants displayed no phenotype under normal growth conditions. However, under low light conditions, their growth rate was significantly reduced as compared with the wild-type, due to a lowered efficiency of the light reaction of photosynthesis. We show that this phenotype is caused by the deficiency in a pigment–protein complex of the light-harvesting antenna of photosystem II and hence by a reduced efficiency of photon capture when light availability is limiting. Our results indicate that, in contrast to the current view, light-harvesting complexes do not only consist of the classical pigment-binding proteins, but may contain small structural subunits in addition. These subunits appear to be crucial architectural factors for the assembly and/or maintenance of stable light-harvesting complexes. PMID:10769029

  18. Cloud-based Architecture Capabilities Summary Report

    SciTech Connect

    Vang, Leng; Prescott, Steven R; Smith, Curtis

    2014-09-01

    In collaborating scientific research arena it is important to have an environment where analysts have access to a shared of information documents, software tools and be able to accurately maintain and track historical changes in models. A new cloud-based environment would be accessible remotely from anywhere regardless of computing platforms given that the platform has available of Internet access and proper browser capabilities. Information stored at this environment would be restricted based on user assigned credentials. This report reviews development of a Cloud-based Architecture Capabilities (CAC) as a web portal for PRA tools.

  19. Machine-Learning Approach for Design of Nanomagnetic-Based Antennas

    NASA Astrophysics Data System (ADS)

    Gianfagna, Carmine; Yu, Huan; Swaminathan, Madhavan; Pulugurtha, Raj; Tummala, Rao; Antonini, Giulio

    2017-08-01

    We propose a machine-learning approach for design of planar inverted-F antennas with a magneto-dielectric nanocomposite substrate. It is shown that machine-learning techniques can be efficiently used to characterize nanomagnetic-based antennas by accurately mapping the particle radius and volume fraction of the nanomagnetic material to antenna parameters such as gain, bandwidth, radiation efficiency, and resonant frequency. A modified mixing rule model is also presented. In addition, the inverse problem is addressed through machine learning as well, where given the antenna parameters, the corresponding design space of possible material parameters is identified.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    The broadband directive emission from the use of waveguided metamaterials is numerically and experimentally reported. The metamaterials, which are composed of non-resonant circular complementary closed ring structures printed on a dielectric substrate, are designed to obey the refractive index of a Luneburg lens. An arc array of planar radiating slot antennas placed at the periphery of the lens is used as wave launchers. A prototype of the lens associated with the feed structures has been fabricated using standard lithography techniques. To experimentally demonstrate the broadband focusing properties and directive emissions, far-field radiation patterns have been measured. Furthermore, this metamaterial-based lens can be used to achieve beam-scanning with a coverage of up to 120 °. Far-field measurements agree qualitatively with calculated near-field distributions.

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

    SciTech Connect

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

    2014-05-21

    The broadband directive emission from the use of waveguided metamaterials is numerically and experimentally reported. The metamaterials, which are composed of non-resonant circular complementary closed ring structures printed on a dielectric substrate, are designed to obey the refractive index of a Luneburg lens. An arc array of planar radiating slot antennas placed at the periphery of the lens is used as wave launchers. A prototype of the lens associated with the feed structures has been fabricated using standard lithography techniques. To experimentally demonstrate the broadband focusing properties and directive emissions, far-field radiation patterns have been measured. Furthermore, this metamaterial-based lens can be used to achieve beam-scanning with a coverage of up to 120 °. Far-field measurements agree qualitatively with calculated near-field distributions.

  2. Low power adder based auditory filter architecture.

    PubMed

    Rahiman, P F Khaleelur; Jayanthi, V S

    2014-01-01

    Cochlea devices are powered up with the help of batteries and they should possess long working life to avoid replacing of devices at regular interval of years. Hence the devices with low power consumptions are required. In cochlea devices there are numerous filters, each responsible for frequency variant signals, which helps in identifying speech signals of different audible range. In this paper, multiplierless lookup table (LUT) based auditory filter is implemented. Power aware adder architectures are utilized to add the output samples of the LUT, available at every clock cycle. The design is developed and modeled using Verilog HDL, simulated using Mentor Graphics Model-Sim Simulator, and synthesized using Synopsys Design Compiler tool. The design was mapped to TSMC 65 nm technological node. The standard ASIC design methodology has been adapted to carry out the power analysis. The proposed FIR filter architecture has reduced the leakage power by 15% and increased its performance by 2.76%.

  3. Low Power Adder Based Auditory Filter Architecture

    PubMed Central

    Jayanthi, V. S.

    2014-01-01

    Cochlea devices are powered up with the help of batteries and they should possess long working life to avoid replacing of devices at regular interval of years. Hence the devices with low power consumptions are required. In cochlea devices there are numerous filters, each responsible for frequency variant signals, which helps in identifying speech signals of different audible range. In this paper, multiplierless lookup table (LUT) based auditory filter is implemented. Power aware adder architectures are utilized to add the output samples of the LUT, available at every clock cycle. The design is developed and modeled using Verilog HDL, simulated using Mentor Graphics Model-Sim Simulator, and synthesized using Synopsys Design Compiler tool. The design was mapped to TSMC 65 nm technological node. The standard ASIC design methodology has been adapted to carry out the power analysis. The proposed FIR filter architecture has reduced the leakage power by 15% and increased its performance by 2.76%. PMID:25506073

  4. Multi-functional Chassis-based Antennas Using Characteristic Mode Theory

    NASA Astrophysics Data System (ADS)

    Kishor, Krishna Kumar

    Designing antennas for handheld devices is quite challenging primarily due to the limited real-estate available, and the fact that internal antennas occupy a large volume. With the need to support a variety of radio systems such as GSM, LTE and WiFi that operate in a wide range of frequency bands, multi-band, wideband and frequency reconfigurable antenna designs have been explored in the literature. Moreover, to support higher data rates, the Long Term Evolution Advanced (LTE-A) standard has been introduced, which requires supporting multiple input multiple output (MIMO) antenna technology and carrier aggregation (CA) on a handheld device. Both of these benefit from the use of multiple antennas or multi-port antennas, but with the limited space available, adding more internal antennas may not be easily possible. Additionally, to realize the benefits of these technologies the multiple antenna ports have to be well isolated from each other. This thesis explores the utilization of the ground plane (or chassis) of a handheld device as an antenna to meet some of these challenges. To achieve this, the theory of characteristic modes (TCM) for conducting bodies is relied upon, to determine the eigen-currents supported on the chassis. The orthogonality properties of these eigencurrents, and their corresponding far-field eigenfields (electric and magnetic) makes TCM a good tool to design multiple antennas with high isolation. This is demonstrated in this thesis via the design of four chassis-based antennas that have different functionalities. The first design is a two port MIMO antenna utilizing a combination of eigenmodes to achieve port isolation. The second design is a pattern reconfigurable MIMO antenna that can operate in two states at 2.28 GHz. The third design is a four port antenna that operates in three frequency bands, with two bands below 1 GHz for CA and the remaining two ports for MIMO communication. The final design is a five port antenna that supports MIMO

  5. Options for a lunar base surface architecture

    NASA Technical Reports Server (NTRS)

    Roberts, Barney B.

    1992-01-01

    The Planet Surface Systems Office at the NASA Johnson Space Center has participated in an analysis of the Space Exploration Initiative architectures described in the Synthesis Group report. This effort involves a Systems Engineering and Integration effort to define point designs for evolving lunar and Mars bases that support substantial science, exploration, and resource production objectives. The analysis addresses systems-level designs; element requirements and conceptual designs; assessments of precursor and technology needs; and overall programmatics and schedules. This paper focuses on the results of the study of the Space Resource Utilization Architecture. This architecture develops the capability to extract useful materials from the indigenous resources of the Moon and Mars. On the Moon, a substantial infrastructure is emplaced which can support a crew of up to twelve. Two major process lines are developed: one produces oxygen, ceramics, and metals; the other produces hydrogen, helium, and other volatiles. The Moon is also used for a simulation of a Mars mission. Significant science capabilities are established in conjunction with resource development. Exploration includes remote global surveys and piloted sorties of local and regional areas. Science accommodations include planetary science, astronomy, and biomedical research. Greenhouses are established to provide a substantial amount of food needs.

  6. Medical nanorobot architecture based on nanobioelectronics.

    PubMed

    Cavalcanti, Adriano; Shirinzadeh, Bijan; Freitas, Robert A; Kretly, Luiz C

    2007-01-01

    This work describes an innovative medical nanorobot architecture based on important discoveries in nanotechnology, integrated circuit patents, and some publications, directly or indirectly related to one of the most challenging new fields of science: molecular machines. Thus, the architecture described in this paper reflects, and is supported by, some remarkable recent achievements and patents in nanoelectronics, wireless communication and power transmission techniques, nanotubes, lithography, biomedical instrumentation, genetics, and photonics. We also describe how medicine can benefit from the joint development of nanodevices which are derived, and which integrate techniques, from artificial intelligence, nanotechnology, and embedded smart sensors. Teleoperated surgical procedures, early disease diagnosis, and pervasive patient monitoring are some possible applications of nanorobots, reflecting progress along a roadmap for the gradual and practical development of nanorobots. To illustrate the described nanorobot architecture, a computational 3D approach with the application of nanorobots for diabetes is simulated using clinical data. Theoretical and practical analysis of system integration modeling is one important aspect for supporting the rapid development in the emerging field of nanotechnology. This provides useful directions for further research and development of medical nanorobotics and suggests a time frame in which nanorobots may be expected to be available for common utilization in therapeutic and medical procedures.

  7. Options for a lunar base surface architecture

    NASA Astrophysics Data System (ADS)

    Roberts, Barney B.

    1992-02-01

    The Planet Surface Systems Office at the NASA Johnson Space Center has participated in an analysis of the Space Exploration Initiative architectures described in the Synthesis Group report. This effort involves a Systems Engineering and Integration effort to define point designs for evolving lunar and Mars bases that support substantial science, exploration, and resource production objectives. The analysis addresses systems-level designs; element requirements and conceptual designs; assessments of precursor and technology needs; and overall programmatics and schedules. This paper focuses on the results of the study of the Space Resource Utilization Architecture. This architecture develops the capability to extract useful materials from the indigenous resources of the Moon and Mars. On the Moon, a substantial infrastructure is emplaced which can support a crew of up to twelve. Two major process lines are developed: one produces oxygen, ceramics, and metals; the other produces hydrogen, helium, and other volatiles. The Moon is also used for a simulation of a Mars mission. Significant science capabilities are established in conjunction with resource development. Exploration includes remote global surveys and piloted sorties of local and regional areas. Science accommodations include planetary science, astronomy, and biomedical research. Greenhouses are established to provide a substantial amount of food needs.

  8. Highly Omnidirectional and Frequency Controllable Carbon/Polyaniline-based 2D and 3D Monopole Antenna

    NASA Astrophysics Data System (ADS)

    Shin, Keun-Young; Kim, Minkyu; Lee, James S.; Jang, Jyongsik

    2015-09-01

    Highly omnidirectional and frequency controllable carbon/polyaniline (C/PANI)-based, two- (2D) and three-dimensional (3D) monopole antennas were fabricated using screen-printing and a one-step, dimensionally confined hydrothermal strategy, respectively. Solvated C/PANI was synthesized by low-temperature interfacial polymerization, during which strong π-π interactions between graphene and the quinoid rings of PANI resulted in an expanded PANI conformation with enhanced crystallinity and improved mechanical and electrical properties. Compared to antennas composed of pristine carbon or PANI-based 2D monopole structures, 2D monopole antennas composed of this enhanced hybrid material were highly efficient and amenable to high-frequency, omnidirectional electromagnetic waves. The mean frequency of C/PANI fiber-based 3D monopole antennas could be controlled by simply cutting and stretching the antenna. These antennas attained high peak gain (3.60 dBi), high directivity (3.91 dBi) and radiation efficiency (92.12%) relative to 2D monopole antenna. These improvements were attributed the high packing density and aspect ratios of C/PANI fibers and the removal of the flexible substrate. This approach offers a valuable and promising tool for producing highly omnidirectional and frequency-controllable, carbon-based monopole antennas for use in wireless networking communications on industrial, scientific, and medical (ISM) bands.

  9. Highly Omnidirectional and Frequency Controllable Carbon/Polyaniline-based 2D and 3D Monopole Antenna.

    PubMed

    Shin, Keun-Young; Kim, Minkyu; Lee, James S; Jang, Jyongsik

    2015-09-04

    Highly omnidirectional and frequency controllable carbon/polyaniline (C/PANI)-based, two- (2D) and three-dimensional (3D) monopole antennas were fabricated using screen-printing and a one-step, dimensionally confined hydrothermal strategy, respectively. Solvated C/PANI was synthesized by low-temperature interfacial polymerization, during which strong π-π interactions between graphene and the quinoid rings of PANI resulted in an expanded PANI conformation with enhanced crystallinity and improved mechanical and electrical properties. Compared to antennas composed of pristine carbon or PANI-based 2D monopole structures, 2D monopole antennas composed of this enhanced hybrid material were highly efficient and amenable to high-frequency, omnidirectional electromagnetic waves. The mean frequency of C/PANI fiber-based 3D monopole antennas could be controlled by simply cutting and stretching the antenna. These antennas attained high peak gain (3.60 dBi), high directivity (3.91 dBi) and radiation efficiency (92.12%) relative to 2D monopole antenna. These improvements were attributed the high packing density and aspect ratios of C/PANI fibers and the removal of the flexible substrate. This approach offers a valuable and promising tool for producing highly omnidirectional and frequency-controllable, carbon-based monopole antennas for use in wireless networking communications on industrial, scientific, and medical (ISM) bands.

  10. Enhanced Nonlinear Effect of Lithium Niobate Based Periodic Nano-antenna Array

    NASA Astrophysics Data System (ADS)

    Pei, X. L.; Bai, S. A.; Tian, J. Y.; Ghosh, P.; Li, Q.; Qiu, M.

    2017-06-01

    We report nonlinear properties of lithium niobate based periodic nano-antenna array. The resonances of this nano-antenna array can be engineered by tuning the geometrical parameters. The nonlinear effect gets enhanced when the electric and magnetic resonances overlap.

  11. Highly Omnidirectional and Frequency Controllable Carbon/Polyaniline-based 2D and 3D Monopole Antenna

    PubMed Central

    Shin, Keun-Young; Kim, Minkyu; Lee, James S.; Jang, Jyongsik

    2015-01-01

    Highly omnidirectional and frequency controllable carbon/polyaniline (C/PANI)-based, two- (2D) and three-dimensional (3D) monopole antennas were fabricated using screen-printing and a one-step, dimensionally confined hydrothermal strategy, respectively. Solvated C/PANI was synthesized by low-temperature interfacial polymerization, during which strong π–π interactions between graphene and the quinoid rings of PANI resulted in an expanded PANI conformation with enhanced crystallinity and improved mechanical and electrical properties. Compared to antennas composed of pristine carbon or PANI-based 2D monopole structures, 2D monopole antennas composed of this enhanced hybrid material were highly efficient and amenable to high-frequency, omnidirectional electromagnetic waves. The mean frequency of C/PANI fiber-based 3D monopole antennas could be controlled by simply cutting and stretching the antenna. These antennas attained high peak gain (3.60 dBi), high directivity (3.91 dBi) and radiation efficiency (92.12%) relative to 2D monopole antenna. These improvements were attributed the high packing density and aspect ratios of C/PANI fibers and the removal of the flexible substrate. This approach offers a valuable and promising tool for producing highly omnidirectional and frequency-controllable, carbon-based monopole antennas for use in wireless networking communications on industrial, scientific, and medical (ISM) bands. PMID:26338090

  12. An Analysis of an Improved Bus-Based Multiprocessor Architecture

    NASA Technical Reports Server (NTRS)

    Ricks, Kenneth G.; Wells, B. Earl

    1998-01-01

    This paper analyses the effectiveness of a hybrid multiprocessing/multicomputing architecture that is based upon a single-board-computer multiprocessor (SBCM) architecture. Based upon empirical analysis using discrete event simulations and Monte Carlo techniques, this hybrid architecture, called the enhanced single-board-computer multiprocessor (ESBCM), is shown to have improved performance and scalability characteristics over current SBCM designs.

  13. Investigation of fluorine-doped tin oxide based optically transparent E-shaped patch antenna for terahertz communications

    SciTech Connect

    Anand, S. E-mail: darak.mayur@gmail.com Darak, Mayur Sudesh E-mail: darak.mayur@gmail.com Kumar, D. Sriram E-mail: darak.mayur@gmail.com

    2014-10-15

    In this paper, a fluorine-doped tin oxide based optically transparent E-shaped patch antenna is designed and its radiation performance is analyzed in the 705 – 804 GHz band. As optically transparent antennas can be mounted on optical display, they facilitate the reduction of overall system size. The proposed antenna design is simulated using electromagnetic solver - Ansys HFSS and its characteristics such as impedance bandwidth, directivity, radiation efficiency and gain are observed. Results show that the fluorine-doped tin oxide based optically transparent patch antenna overcomes the conventional patch antenna limitations and thus the same can be used for solar cell antenna used in satellite systems.

  14. Antenna Technologies for NASA Applications

    NASA Technical Reports Server (NTRS)

    Miranda, Felix

    2007-01-01

    This presentation addresses the efforts being performed at GRC to develop antenna technology in support of NASA s Exploration Vision. In particular, the presentation discusses the communications architecture asset-specific data services, as well as wide area coverage, high gain, low mass deployable antennas. Phased array antennas as well as electrically small, lightweight, low power, multifunctional antennas will be also discussed.

  15. Antenna Technologies for NASA Applications

    NASA Technical Reports Server (NTRS)

    Miranda, Felix A.

    2006-01-01

    This presentation addresses the efforts being performed at GRC to develop antenna technology in support of NASA s Exploration Vision. In particular, the presentation discusses the communications architecture asset-specific data services, as well as wide area coverage, high gain, low mass deployable antennas. Phased array antennas as well as electrically small, lightweight, low power, multifunctional antennas will be also discussed.

  16. Design and implementation of dual-band antennas based on a complementary split ring resonators

    NASA Astrophysics Data System (ADS)

    Ortiz, Noelia; Iriarte, Juan Carlos; Crespo, Gonzalo; Falcone, Francisco

    2015-07-01

    A simple dual-band antenna design and implementation method is proposed in this work, based on the equivalent media properties inspired by resonant metamaterial elements. The equivalent circuit model of dual-band patch antennas based on a complementary split ring resonator (CSRR) is presented and validated. The dual-band patch antenna is designed etching a CSRR in the patch of a conventional rectangular microstrip patch antenna. The first resonance is governed by the quasi-static resonance of the CSRR while the second resonance is originated by the rectangular patch. The fact of etching a CSRR on a rectangular patch antenna also produces a miniaturization of a conventional patch antenna. The equivalent circuit model proposed in this letter is sound in order to understand the functionality of dual-band patch antennas based on a CSRR. Good agreement between simulation, equivalent circuit model and experimental results is shown and discussed. These results lead the equivalent circuit model to become a simple and straightforward tool for the design of this type of multiband antennas, of low cost and versatile operation for a broad range of wireless communication systems.

  17. Novel On-wafer Radiation Pattern Measurement Technique for MEMS Actuator Based Reconfigurable Patch Antennas

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.

    2002-01-01

    The paper presents a novel on-wafer, antenna far field pattern measurement technique for microelectromechanical systems (MEMS) based reconfigurable patch antennas. The measurement technique significantly reduces the time and the cost associated with the characterization of printed antennas, fabricated on a semiconductor wafer or dielectric substrate. To measure the radiation patterns, the RF probe station is modified to accommodate an open-ended rectangular waveguide as the rotating linearly polarized sampling antenna. The open-ended waveguide is attached through a coaxial rotary joint to a Plexiglas(Trademark) arm and is driven along an arc by a stepper motor. Thus, the spinning open-ended waveguide can sample the relative field intensity of the patch as a function of the angle from bore sight. The experimental results include the measured linearly polarized and circularly polarized radiation patterns for MEMS-based frequency reconfigurable rectangular and polarization reconfigurable nearly square patch antennas, respectively.

  18. Graphene circular polarization analyzer based on spiral metal triangle antennas arrays.

    PubMed

    Zhu, Bofeng; Ren, Guobin; Gao, Yixiao; Wu, Beilei; Wan, Chenglong; Jian, Shuisheng

    2015-09-21

    In this paper we propose a circular polarization analyzer based on spiral metal triangle antenna arrays deposited on graphene. Via the dipole antenna resonances, plasmons are excited on graphene surface and the wavefront can be tailed by arranging metal antennas into linetype, circular or spiral arrays. Especially, for spiral antenna arrays, the geometric phase effect can be cancelled by or superposed on the chirality carried within circular polarization incidence, producing spatially separated solid dot or donut shape fields at the center. Such a phenomenon enables the graphene based spiral metal triangle antennas arrays to achieve functionality as a circular polarization analyzer. Extinction ratio over 550 can be achieved and the working wavelength can be tuned by adjusting graphene Fermi level dynamically. The proposed analyzer may find applications in analyzing chiral molecules using different circularly polarized waves.

  19. An efficient hexagonal switched beam antenna structure based on Fabry-Perot cavity leaky-wave antenna

    NASA Astrophysics Data System (ADS)

    Aymen El Cafsi, Mohamed; Nedil, Mourad; Osman, Lotfi; Gharsallah, Ali

    2015-11-01

    A novel design of switched beam antenna (SBA) system based on Fabry-Perot cavity leaky-wave antenna (FPC LWA) is designed and fabricated for base station operating in the unlicensed ISM central frequency band at 5.8 GHz of the wireless local area network (WLAN) standard. The proposed SBA is designed with hexagonal shape of FPC LWA Arrays in order to get 360° of coverage. The single element of FPC LWA array is composed of a patch antenna and covered by a Partially Reflective Surface (PRS), which is composed of a Metal Strip Grating and printed on a high permittivity Superstrate. First, the Transmission Line Model of FPC LWA is introduced to analyse and calculate the far-field components in E- and H planes by using the Transverse Equivalent Network. This approach is then compared with other full wave's commercial software such as Ansoft HFSS and CST Microwave Studio. Second, a parametric study is performed to evaluate the effect of the angle formed by the two successive FPC LWA on the radiation efficiency of the activate sector. To examine the performance of the proposed SBA, experimental prototype was fabricated and measured. As a result, multiple orthogonal beams (six beams) of 10 dBi of gain with low Side Lobes Level and 360° of coverage are produced. This SBA structure is suitable for WLAN communication systems.

  20. Link Correlation Based Transmit Sector Antenna Selection for Alamouti Coded OFDM

    NASA Astrophysics Data System (ADS)

    Ahn, Chang-Jun

    In MIMO systems, the deployment of a multiple antenna technique can enhance the system performance. However, since the cost of RF transmitters is much higher than that of antennas, there is growing interest in techniques that use a larger number of antennas than the number of RF transmitters. These methods rely on selecting the optimal transmitter antennas and connecting them to the respective. In this case, feedback information (FBI) is required to select the optimal transmitter antenna elements. Since FBI is control overhead, the rate of the feedback is limited. This motivates the study of limited feedback techniques where only partial or quantized information from the receiver is conveyed back to the transmitter. However, in MIMO/OFDM systems, it is difficult to develop an effective FBI quantization method for choosing the space-time, space-frequency, or space-time-frequency processing due to the numerous subchannels. Moreover, MIMO/OFDM systems require antenna separation of 5 ∼ 10 wavelengths to keep the correlation coefficient below 0.7 to achieve a diversity gain. In this case, the base station requires a large space to set up multiple antennas. To reduce these problems, in this paper, we propose the link correlation based transmit sector antenna selection for Alamouti coded OFDM without FBI.

  1. Integration of Directional Antennas in an RSS Fingerprinting-Based Indoor Localization System.

    PubMed

    Guzmán-Quirós, Raúl; Martínez-Sala, Alejandro; Gómez-Tornero, José Luis; García-Haro, Joan

    2015-12-23

    In this paper, the integration of directional antennas in a room-level received signal strength (RSS) fingerprinting-based indoor localization system (ILS) is studied. The sensor reader (SR), which is in charge of capturing the RSS to infer the tag position, can be attached to an omnidirectional or directional antenna. Unlike commonly-employed omnidirectional antennas, directional antennas can receive a stronger signal from the direction in which they are pointed, resulting in a different RSS distributions in space and, hence, more distinguishable fingerprints. A simulation tool and a system management software have been also developed to control the system and assist the initial antenna deployment, reducing time-consuming costs. A prototype was mounted in a real scenario, with a number of SRs with omnidirectional and directional antennas properly positioned. Different antenna configurations have been studied, evidencing a promising capability of directional antennas to enhance the performance of RSS fingerprinting-based ILS, reducing the number of required SRs and also increasing the localization success.

  2. Integration of Directional Antennas in an RSS Fingerprinting-Based Indoor Localization System

    PubMed Central

    Guzmán-Quirós, Raúl; Martínez-Sala, Alejandro; Gómez-Tornero, José Luis; García-Haro, Joan

    2015-01-01

    In this paper, the integration of directional antennas in a room-level received signal strength (RSS) fingerprinting-based indoor localization system (ILS) is studied. The sensor reader (SR), which is in charge of capturing the RSS to infer the tag position, can be attached to an omnidirectional or directional antenna. Unlike commonly-employed omnidirectional antennas, directional antennas can receive a stronger signal from the direction in which they are pointed, resulting in a different RSS distributions in space and, hence, more distinguishable fingerprints. A simulation tool and a system management software have been also developed to control the system and assist the initial antenna deployment, reducing time-consuming costs. A prototype was mounted in a real scenario, with a number of SRs with omnidirectional and directional antennas properly positioned. Different antenna configurations have been studied, evidencing a promising capability of directional antennas to enhance the performance of RSS fingerprinting-based ILS, reducing the number of required SRs and also increasing the localization success. PMID:26703620

  3. A High Performance COTS Based Computer Architecture

    NASA Astrophysics Data System (ADS)

    Patte, Mathieu; Grimoldi, Raoul; Trautner, Roland

    2014-08-01

    Using Commercial Off The Shelf (COTS) electronic components for space applications is a long standing idea. Indeed the difference in processing performance and energy efficiency between radiation hardened components and COTS components is so important that COTS components are very attractive for use in mass and power constrained systems. However using COTS components in space is not straightforward as one must account with the effects of the space environment on the COTS components behavior. In the frame of the ESA funded activity called High Performance COTS Based Computer, Airbus Defense and Space and its subcontractor OHB CGS have developed and prototyped a versatile COTS based architecture for high performance processing. The rest of the paper is organized as follows: in a first section we will start by recapitulating the interests and constraints of using COTS components for space applications; then we will briefly describe existing fault mitigation architectures and present our solution for fault mitigation based on a component called the SmartIO; in the last part of the paper we will describe the prototyping activities executed during the HiP CBC project.

  4. Graphene-based Yagi-Uda antenna with reconfigurable radiation patterns

    NASA Astrophysics Data System (ADS)

    Wu, Yongle; Qu, Meijun; Jiao, Lingxiao; Liu, Yuanan; Ghassemlooy, Zabih

    2016-06-01

    This paper presents a radiation pattern reconfigurable Yagi-Uda antenna based on graphene operating at terahertz frequencies. The antenna can be reconfigured to change the main beam pattern into two or four different radiation directions. The proposed antenna consists of a driven dipole radiation conductor, parasitic strips and embedded graphene. The hybrid graphene-metal implementation enables the antenna to have dynamic surface conductivity, which can be tuned by changing the chemical potentials. Therefore, the main beam direction, the resonance frequency, and the front-to-back ratio of the proposed antenna can be controlled by tuning the chemical potentials of the graphene embedded in different positions. The proposed two-beam reconfigurable Yagi-Uda antenna can achieve excellent unidirectional symmetrical radiation pattern with the front-to-back ratio of 11.9 dB and the10-dB impedance bandwidth of 15%. The different radiation directivity of the two-beam reconfigurable antenna can be achieved by controlling the chemical potentials of the graphene embedded in the parasitic stubs. The achievable peak gain of the proposed two-beam reconfigurable antenna is about 7.8 dB. Furthermore, we propose a four-beam reconfigurable Yagi-Uda antenna, which has stable reflection-coefficient performance although four main beams in reconfigurable cases point to four totally different directions. The corresponding peak gain, front-to-back ratio, and 10-dB impedance bandwidth of the four-beam reconfigurable antenna are about 6.4 dB, 12 dB, and 10%, respectively. Therefore, this novel design method of reconfigurable antennas is extremely promising for beam-scanning in terahertz and mid-infrared plasmonic devices and systems.

  5. Graphene-based Yagi-Uda antenna with reconfigurable radiation patterns

    SciTech Connect

    Wu, Yongle Qu, Meijun; Jiao, Lingxiao; Liu, Yuanan; Ghassemlooy, Zabih

    2016-06-15

    This paper presents a radiation pattern reconfigurable Yagi-Uda antenna based on graphene operating at terahertz frequencies. The antenna can be reconfigured to change the main beam pattern into two or four different radiation directions. The proposed antenna consists of a driven dipole radiation conductor, parasitic strips and embedded graphene. The hybrid graphene-metal implementation enables the antenna to have dynamic surface conductivity, which can be tuned by changing the chemical potentials. Therefore, the main beam direction, the resonance frequency, and the front-to-back ratio of the proposed antenna can be controlled by tuning the chemical potentials of the graphene embedded in different positions. The proposed two-beam reconfigurable Yagi-Uda antenna can achieve excellent unidirectional symmetrical radiation pattern with the front-to-back ratio of 11.9 dB and the10-dB impedance bandwidth of 15%. The different radiation directivity of the two-beam reconfigurable antenna can be achieved by controlling the chemical potentials of the graphene embedded in the parasitic stubs. The achievable peak gain of the proposed two-beam reconfigurable antenna is about 7.8 dB. Furthermore, we propose a four-beam reconfigurable Yagi-Uda antenna, which has stable reflection-coefficient performance although four main beams in reconfigurable cases point to four totally different directions. The corresponding peak gain, front-to-back ratio, and 10-dB impedance bandwidth of the four-beam reconfigurable antenna are about 6.4 dB, 12 dB, and 10%, respectively. Therefore, this novel design method of reconfigurable antennas is extremely promising for beam-scanning in terahertz and mid-infrared plasmonic devices and systems.

  6. Hybrid Power Management-Based Vehicle Architecture

    NASA Technical Reports Server (NTRS)

    Eichenberg, Dennis J.

    2011-01-01

    Hybrid Power Management (HPM) is the integration of diverse, state-of-the-art power devices in an optimal configuration for space and terrestrial applications (s ee figure). The appropriate application and control of the various power devices significantly improves overall system performance and efficiency. The basic vehicle architecture consists of a primary power source, and possibly other power sources, that provides all power to a common energy storage system that is used to power the drive motors and vehicle accessory systems. This architecture also provides power as an emergency power system. Each component is independent, permitting it to be optimized for its intended purpose. The key element of HPM is the energy storage system. All generated power is sent to the energy storage system, and all loads derive their power from that system. This can significantly reduce the power requirement of the primary power source, while increasing the vehicle reliability. Ultracapacitors are ideal for an HPM-based energy storage system due to their exceptionally long cycle life, high reliability, high efficiency, high power density, and excellent low-temperature performance. Multiple power sources and multiple loads are easily incorporated into an HPM-based vehicle. A gas turbine is a good primary power source because of its high efficiency, high power density, long life, high reliability, and ability to operate on a wide range of fuels. An HPM controller maintains optimal control over each vehicle component. This flexible operating system can be applied to all vehicles to considerably improve vehicle efficiency, reliability, safety, security, and performance. The HPM-based vehicle architecture has many advantages over conventional vehicle architectures. Ultracapacitors have a much longer cycle life than batteries, which greatly improves system reliability, reduces life-of-system costs, and reduces environmental impact as ultracapacitors will probably never need to be

  7. Pressure and shear sensing based on microstrip antennas

    NASA Astrophysics Data System (ADS)

    Mohammad, I.; Huang, H.

    2012-04-01

    A foot ulcer is the initiating factor in 85% of all diabetic amputations. Ulcer formation is believed to be contributed by both pressure and shear forces. There are commercially available instruments that can measure plantar pressure. However, instruments for plantar shear measurement are limited. In this paper, we investigate the application of antenna sensors for shear and pressure measurement. The principle of operation of both antenna sensors will be discussed first, followed by detailed descriptions on the antenna designs, sensor fabrication, experimental setup, procedure and results. Because the antenna sensors are small in size, can be wirelessly interrogated, and are frequency multiplexable, we plan to embed them in shoes for simultaneous mapping of plantar shear and pressure distributions in the future.

  8. Imaging individual proteins and nanodomains on intact cell membranes with a probe-based optical antenna.

    PubMed

    van Zanten, Thomas S; Lopez-Bosque, Maria J; Garcia-Parajo, Maria F

    2010-01-01

    Optical antennas that confine and enhance electromagnetic fields in a nanometric region hold great potential for nanobioimaging and biosensing. Probe-based monopole optical antennas are fabricated to enhance fields localized to <30 nm near the antenna apex in aqueous conditions. These probes are used under appropriate excitation antenna conditions to image individual antibodies with an unprecedented resolution of 26 +/- 4 nm and virtually no surrounding background. On intact cell membranes in physiological conditions, the obtained resolution is 30 +/- 6 nm. Importantly, the method allows individual proteins to be distinguished from nanodomains and the degree of clustering to be quantified by directly measuring physical size and intensity of individual fluorescent spots. Improved antenna geometries should lead to true live cell imaging below 10-nm resolution with position accuracy in the subnanometric range.

  9. A reconfigurable subwavelength plasmonic fano nano-antenna based on split ring resonator

    NASA Astrophysics Data System (ADS)

    Hosseinbeig, Ahmad; Pirooj, Azadeh; Zarrabi, Ferdows B.

    2017-02-01

    In this article, a reconfigurable subwavelength plasmonic nano-antenna with Fano resonance effect is presented based on the dual ring structure. In order to achieve reconfigurable characteristics, the interaction of gold with graphene is studied. SiN substrate with refractive index of 1.98 and gold with Palik optical characteristic modified for metal layer are utilized in the design of the proposed nano-antenna. Simulations are performed by using CST Microwave Studio. The biasing effect on extinction cross section is studied for 0 to 0.8 eV. It is shown that the gap method is useful for exciting the Fano resonance in the dual ring nano-antenna and there is only a plasmonic resonance in the simple dual ring antenna. The proposed nano-antenna is useful for THz medical spectroscopy due to its simple design and the ability to control the second resonance frequency by changing the bias of the graphene.

  10. Research on the space architecture based on Fractal Theory

    NASA Astrophysics Data System (ADS)

    Jing-Ming, LI

    2017-08-01

    This article describes four space architecture models with pictures based on Fractal Theory, and tries to sum up the advantages and disadvantages of the four basic space architecture models which can produce artificial gravity. Based on Fractal Theory, the author also puts forward to expanding the space architecture with powerful Cellular structures. The Conclusion of this research is that the use of honeycomb structures and four basic models can create lots of fantastic space architecture which provides artificial gravity. Therefore, this paper will have a profound impact on the development of space architecture.

  11. Domain tree-based analysis of protein architecture evolution.

    PubMed

    Forslund, Kristoffer; Henricson, Anna; Hollich, Volker; Sonnhammer, Erik L L

    2008-02-01

    Understanding the dynamics behind domain architecture evolution is of great importance to unravel the functions of proteins. Complex architectures have been created throughout evolution by rearrangement and duplication events. An interesting question is how many times a particular architecture has been created, a form of convergent evolution or domain architecture reinvention. Previous studies have approached this issue by comparing architectures found in different species. We wanted to achieve a finer-grained analysis by reconstructing protein architectures on complete domain trees. The prevalence of domain architecture reinvention in 96 genomes was investigated with a novel domain tree-based method that uses maximum parsimony for inferring ancestral protein architectures. Domain architectures were taken from Pfam. To ensure robustness, we applied the method to bootstrap trees and only considered results with strong statistical support. We detected multiple origins for 12.4% of the scored architectures. In a much smaller data set, the subset of completely domain-assigned proteins, the figure was 5.6%. These results indicate that domain architecture reinvention is a much more common phenomenon than previously thought. We also determined which domains are most frequent in multiply created architectures and assessed whether specific functions could be attributed to them. However, no strong functional bias was found in architectures with multiple origins.

  12. Novel metamaterial based antennas for flexible wireless systems

    NASA Astrophysics Data System (ADS)

    Khaleel, Haider Raad

    Recent years have witnessed a great deal of interest from both academia and industry in the field of flexible electronic systems. This research topic tops the pyramid of research priorities requested by many national research agencies. Consistently, flexible electronic systems require the integration of flexible antennas operating in specific frequency bands to provide wireless connectivity which is highly demanded by today's information oriented society. On the other hand, metamaterials have become very popular in the design of contemporary antenna and microwave devices due to their wide range of applications derived from their unique properties which significantly enhances the performance of antennas and RF systems. Accordingly, the integration of metamaterial structures within flexible wireless systems is very beneficial in this growing field of research. A systematic approach to the analysis and design of flexible and conformal antennas and metamaterials is ultimately needed. The research reported in this thesis focuses on developing flexible low profile antennas and metamaterial structures in addition to characterizing their performance when integrated within flexible wireless systems. Three flexible, compact, and extremely low profile (50.8 microm) antennas intended for WLAN, Bluetooth and Ultra Wide Band (UWB) applications are presented. Next, a novel miniaturized Artificial Magnetic Conductor (AMC) and a new technique to enhance the bandwidth of micro-Negative (MNG) metamaterial are reported. Furthermore, the effect of bending on the AMC and MNG metamaterial is investigated in this thesis for the first time. Finally, the findings of this research are utilized in practical applications with specific design constraints including mutual coupling reduction between radiating elements in antenna arrays and MIMO systems and Specific Absorption Rate (SAR) reduction in telemedicine systems.

  13. System-Level Performance of Antenna Arrays in CDMA-Based Cellular Mobile Radio Systems

    NASA Astrophysics Data System (ADS)

    Czylwik, Andreas; Dekorsy, Armin

    2004-12-01

    Smart antennas exploit the inherent spatial diversity of the mobile radio channel, provide an antenna gain, and also enable spatial interference suppression leading to reduced intracell as well as intercell interference. Especially, for the downlink of future CDMA-based mobile communications systems, transmit beamforming is seen as a well-promising smart antenna technique. The main objective of this paper is to study the performance of diverse antenna array topologies when applied for transmit beamforming in the downlink of CDMA-based networks. In this paper, we focus on uniform linear array (ULA) and uniform circular array (UCA) topologies. For the ULA, we consider three-sector base stations with one linear array per sector. While recent research on downlink beamforming is often restricted to one single cell, this study takes into account the important impact of intercell interference on the performance by evaluating complete networks. Especially, from the operator perspective, system capacity and system coverage are very essential parameters of a cellular system so that there is a clear necessity of intensive system level investigations. Apart from delivering assessments on the performance of the diverse antenna array topologies, in the paper also different antenna array parameters, such as element spacing and beamwidth of the sector antennas, are optimized. Although we focus on the network level, fast channel fluctuations are taken into account by including them analytically into the signal-to-interference calculation.

  14. Flying Drosophila stabilize their vision-based velocity controller by sensing wind with their antennae.

    PubMed

    Fuller, Sawyer Buckminster; Straw, Andrew D; Peek, Martin Y; Murray, Richard M; Dickinson, Michael H

    2014-04-01

    Flies and other insects use vision to regulate their groundspeed in flight, enabling them to fly in varying wind conditions. Compared with mechanosensory modalities, however, vision requires a long processing delay (~100 ms) that might introduce instability if operated at high gain. Flies also sense air motion with their antennae, but how this is used in flight control is unknown. We manipulated the antennal function of fruit flies by ablating their aristae, forcing them to rely on vision alone to regulate groundspeed. Arista-ablated flies in flight exhibited significantly greater groundspeed variability than intact flies. We then subjected them to a series of controlled impulsive wind gusts delivered by an air piston and experimentally manipulated antennae and visual feedback. The results show that an antenna-mediated response alters wing motion to cause flies to accelerate in the same direction as the gust. This response opposes flying into a headwind, but flies regularly fly upwind. To resolve this discrepancy, we obtained a dynamic model of the fly's velocity regulator by fitting parameters of candidate models to our experimental data. The model suggests that the groundspeed variability of arista-ablated flies is the result of unstable feedback oscillations caused by the delay and high gain of visual feedback. The antenna response drives active damping with a shorter delay (~20 ms) to stabilize this regulator, in exchange for increasing the effect of rapid wind disturbances. This provides insight into flies' multimodal sensory feedback architecture and constitutes a previously unknown role for the antennae.

  15. All printed antenna based on silver nanoparticles for 1.8 GHz applications

    NASA Astrophysics Data System (ADS)

    Hassan, Arshad; Ali, Shawkat; Bae, Jinho; Lee, Chong Hyun

    2016-08-01

    In this paper, we propose a novel printed antenna for 1.8 GHz band applications. The proposed antenna is made of silver nanoparticle-based radiating element and 0.04-mm thin, transparent and flexible polyethylene terephthalate (PET) substrate. The proposed antenna is designed and simulated by finite-element-method-based high-frequency structure simulator (HFSS). We obtain reflection coefficient of -23 dB, gain of 2.72 dBi and efficiency of 93.33 %. The resonance frequency of the antenna is also verified through national instrument (NI) Multisim simulation on the proposed equivalent circuit. We realize the antenna in a single process by commercial Dimatix material inkjet printer (DMP-3000) at ambient condition and characterize it by using vector network analyzer and spectrum analyzer. The measured reflection coefficient and -10 dB bandwidth are -32.2 dB and 190.5 MHz, respectively, which shows good agreement with HFSS and NI Multisim results. The proposed compact and optimum antenna printed on thin, transparent and fully bendable PET substrate becomes very attractive since it can overcome the limits of cost and size. These results suggest that the proposed antenna is well suitable for electronic devices operating over 1.8 GHz band such as Telos-B and other wearable printed devices.

  16. Design optical antenna and fiber coupling system based on the vector theory of reflection and refraction.

    PubMed

    Jiang, Ping; Yang, Huajun; Mao, Shengqian

    2015-10-05

    A Cassegrain antenna system and an optical fiber coupling system which consists of a plano-concave lens and a plano-convex lens are designed based on the vector theory of reflection and refraction, so as to improve the transmission performance of the optical antenna and fiber coupling system. Three-dimensional ray tracing simulation are performed and results of the optical aberrations calculation and the experimental test show that the aberrations caused by on-axial defocusing, off-axial defocusing and deflection of receiving antenna can be well corrected by the optical fiber coupling system.

  17. A millimeter-wave integrated-circuit antenna based on the Fresnel zone plate

    NASA Astrophysics Data System (ADS)

    Gouker, Mark A.; Smith, Glenn S.

    1992-05-01

    A moderate-gain, easily constructed, millimeter-wave IC antenna based on the Fresnel zone plate has been developed. The gain and beamwidth of the antenna can be varied by adjusting the diameter and focal length of the zone plate. A theory is developed which accurately predicts the on-axis gain, beamwidth, and sidelobe levels of antennas with zone-plate focal lengths greater than 8-9 lambda. Graphs are presented to aid in the design of other IC zone-plate antennas. The performance of the antenna without the reflector and lambda/4 spacer was investigated. The gain of the antenna with nothing behind the zone plate is found to approach that of the fully configured antenna with the lambda/4 spacer and reflector. The reflection from the open rings which is responsible for this phenomenon is enhanced as the dielectric constant of the substrate is increased. Thus, on substrates with high permittivity the reflector and lambda/4 spacer may not be necessary.

  18. Reversibly Stretchable, Optically Transparent Radio-Frequency Antennas Based on Wavy Ag Nanowire Networks.

    PubMed

    Kim, Byoung Soo; Shin, Keun-Young; Pyo, Jun Beom; Lee, Jonghwi; Son, Jeong Gon; Lee, Sang-Soo; Park, Jong Hyuk

    2016-02-03

    We report a facile approach for producing reversibly stretchable, optically transparent radio-frequency antennas based on wavy Ag nanowire (NW) networks. The wavy configuration of Ag NWs is obtained by floating the NW networks on the surface of water, followed by compression. Stretchable antennas are prepared by transferring the compressed NW networks onto elastomeric substrates. The resulting antennas show excellent performance under mechanical deformation due to the wavy configuration, which allows the release of stress applied to the NWs and an increase in the contact area between NWs. The antennas formed from the wavy NW networks exhibit a smaller return loss and a higher radiation efficiency when strained than the antennas formed from the straight NW networks, as well as an improved stability in cyclic deformation tests. Moreover, the wavy NW antennas require a relatively small quantity of NWs, which leads to low production costs and provides an optical transparency. These results demonstrate the potential of these wavy Ag NW antennas in applications of wireless communications for wearable systems.

  19. Performance enhanced miniaturized and electrically tunable patch antenna with patterned permalloy based magneto-dielectric substrate

    NASA Astrophysics Data System (ADS)

    Peng, Yujia; Farid Rahman, B. M.; Wang, Xuehe; Wang, Guoan

    2014-05-01

    Perspective magneto-dielectric materials with high permeability are potential substrates to miniaturize the patch antenna without deteriorating its performance. Besides its high permeability at high frequency, patterned Permalloy (Py) also presents tunable permeability by applying DC current. A performance enhanced miniaturized and electrically tunable patch antenna with patterned Py thin film is first presented and developed in this paper. To suppress the magnetic loss, the Py thin film layer is consisted of an array of 2 μm × 2 μm square Py patterns between the copper patch antenna and dielectric substrate. The DC current could be applied directly on Py patterns through the copper strip lines beneath the Py patterns along the length of patch antenna. The copper strip lines are specially designed with the same width of Py patterns and the thickness much less than the skin depth at the operating frequency, which can reduce their deteriorating effects to the performance of antenna. The structure of the antenna is presented and simulated with high frequency structure simulator. The results show that compared with non-magnetic antenna, the performance of Py thin film based antenna is improved with 50% bandwidth increase from 4 MHz to 8 MHz and 1.2 dB gain enhancement from 1.16 dB to 2.36 dB. The resonant frequency of the antenna could be continuously tuned from 937 MHz to 911 MHz with the permeability of Py thin film changing from 1750 to 1 900 by applying the DC current.

  20. Fast terahertz optoelectronic amplitude modulator based on plasmonic metamaterial antenna arrays and graphene

    NASA Astrophysics Data System (ADS)

    Jessop, David S.; Sol, Christian W. O.; Xiao, Long; Kindness, Stephen J.; Braeuninger-Weimer, Philipp; Lin, Hungyen; Griffiths, Jonathan P.; Ren, Yuan; Kamboj, Varun S.; Hofmann, Stephan; Zeitler, J. Axel; Beere, Harvey E.; Ritchie, David A.; Degl'Innocenti, Riccardo

    2016-02-01

    The growing interest in terahertz (THz) technologies in recent years has seen a wide range of demonstrated applications, spanning from security screening, non-destructive testing, gas sensing, to biomedical imaging and communication. Communication with THz radiation offers the advantage of much higher bandwidths than currently available, in an unallocated spectrum. For this to be realized, optoelectronic components capable of manipulating THz radiation at high speeds and high signal-to-noise ratios must be developed. In this work we demonstrate a room temperature frequency dependent optoelectronic amplitude modulator working at around 2 THz, which incorporates graphene as the tuning medium. The architecture of the modulator is an array of plasmonic dipole antennas surrounded by graphene. By electrostatically doping the graphene via a back gate electrode, the reflection characteristics of the modulator are modified. The modulator is electrically characterized to determine the graphene conductivity and optically characterization, by THz time-domain spectroscopy and a single-mode 2 THz quantum cascade laser, to determine the optical modulation depth and cut-off frequency. A maximum optical modulation depth of ~ 30% is estimated and is found to be most (least) sensitive when the electrical modulation is centered at the point of maximum (minimum) differential resistivity of the graphene. A 3 dB cut-off frequency > 5 MHz, limited only by the area of graphene on the device, is reported. The results agree well with theoretical calculations and numerical simulations, and demonstrate the first steps towards ultra-fast, graphene based THz optoelectronic devices.

  1. Multi-Variable Model-Based Parameter Estimation Model for Antenna Radiation Pattern Prediction

    NASA Technical Reports Server (NTRS)

    Deshpande, Manohar D.; Cravey, Robin L.

    2002-01-01

    A new procedure is presented to develop multi-variable model-based parameter estimation (MBPE) model to predict far field intensity of antenna. By performing MBPE model development procedure on a single variable at a time, the present method requires solution of smaller size matrices. The utility of the present method is demonstrated by determining far field intensity due to a dipole antenna over a frequency range of 100-1000 MHz and elevation angle range of 0-90 degrees.

  2. MoM-based topology optimization method for planar metallic antenna design

    NASA Astrophysics Data System (ADS)

    Liu, Shutian; Wang, Qi; Gao, Renjing

    2016-12-01

    The metallic antenna design problem can be treated as a problem to find the optimal distribution of conductive material in a certain domain. Although this problem is well suited for topology optimization method, the volumetric distribution of conductive material based on 3D finite element method (FEM) has been known to cause numerical bottlenecks such as the skin depth issue, meshed "air regions" and other numerical problems. In this paper a topology optimization method based on the method of moments (MoM) for configuration design of planar metallic antenna was proposed. The candidate structure of the planar metallic antenna was approximately considered as a resistance sheet with position-dependent impedance. In this way, the electromagnetic property of the antenna can be analyzed easily by using the MoM to solve the radiation problem of the resistance sheet in a finite domain. The topology of the antenna was depicted with the distribution of the impedance related to the design parameters or relative densities. The conductive material (metal) was assumed to have zero impedance, whereas the non-conductive material was simulated as a material with a finite but large enough impedance. The interpolation function of the impedance between conductive material and non-conductive material was taken as a tangential function. The design of planar metallic antenna was optimized for maximizing the efficiency at the target frequency. The results illustrated the effectiveness of the method.

  3. Highly integrated VO2-based tunable antenna for millimeter-wave applications

    NASA Astrophysics Data System (ADS)

    Huitema, L.; Crunteanu, A.; Wong, H.; Arnaud, E.

    2017-05-01

    We report the concept of a frequency tunable antenna device operating in the millimeter wave frequency domain. The ability of the antenna to switch between two frequency states is achieved by the monolithic integration of a metal-insulator transition material (vanadium dioxide, VO2). The VO2 material is an insulator at room temperature but can be driven in a high conductivity metallic state when it is electrically activated using a continuous (DC) voltage. The antenna design is based on a slot antenna excited by a microstrip line having a length that can be conveniently varied using a VO2-based switch. Following the high-frequency VO2 material characterization, we present its monolithic integration in the device prototype along with the comparison between the measured and the simulated performances of the agile antenna. Thus, depending on the VO2 material state, the antenna device can be conveniently switched between 33 and 37 GHz operating frequency bands presenting stable radiation patterns with 5.28 dBi and 5.41 dBi maximum gains, respectively.

  4. The constraint based decomposition (CBD) training architecture.

    PubMed

    Draghici, S

    2001-05-01

    The Constraint Based Decomposition (CBD) is a constructive neural network technique that builds a three or four layer network, has guaranteed convergence and can deal with binary, n-ary, class labeled and real-value problems. CBD is shown to be able to solve complicated problems in a simple, fast and reliable manner. The technique is further enhanced by two modifications (locking detection and redundancy elimination) which address the training speed and the efficiency of the internal representation built by the network. The redundancy elimination aims at building more compact architectures while the locking detection aims at improving the training speed. The computational cost of the redundancy elimination is negligible and this enhancement can be used for any problem. However, the computational cost of the locking detection is exponential in the number of dimensions and should only be used in low dimensional spaces. The experimental results show the performance of the algorithm presented in a series of classical benchmark problems including the 2-spiral problem and the Iris, Wine, Glass, Lenses, Ionosphere, Lung cancer, Pima Indians, Bupa, TicTacToe, Balance and Zoo data sets from the UCI machine learning repository. CBD's generalization accuracy is compared with that of C4.5, C4.5 with rules, incremental decision trees, oblique classifiers, linear machine decision trees, CN2, learning vector quantization (LVQ), backpropagation, nearest neighbor, Q* and radial basis functions (RBFs). CBD provides the second best average accuracy on the problems tested as well as the best reliability (the lowest standard deviation).

  5. Design and investigation of planar technology based ultra-wideband antenna with directional radiation patterns

    NASA Astrophysics Data System (ADS)

    Meena, M. L.; Parmar, Girish; Kumar, Mithilesh

    2016-03-01

    A novel design technique based on planar technology for ultra-wideband (UWB) antennas with different ground shape having directional radiation pattern is being presented here. Firstly, the L-shape corner reflector ground plane antenna is designed with microstrip feed line in order to achieve large bandwidth and directivity. Thereafter, for the further improvement in the directivity as well as for better impedance matching the parabolic-shape ground plane has been introduced. The coaxial feed line is given for the proposed directional antenna in order to achieve better impedance matching with 50 ohm transmission line. The simulation analysis of the antenna is done on CST Microwave Studio software using FR-4 substrate having thickness of 1.6 mm and dielectric constant of 4.4. The simulated result shows a good return loss (S11) with respect to -10 dB. The radiation pattern characteristic, angular width, directivity and bandwidth performance of the antenna have also been compared at different resonant frequencies. The designed antennas exhibit low cost, low reflection coefficient and better directivity in the UWB frequency band.

  6. Design and investigation of planar technology based ultra-wideband antenna with directional radiation patterns

    SciTech Connect

    Meena, M. L. Parmar, Girish Kumar, Mithilesh

    2016-03-09

    A novel design technique based on planar technology for ultra-wideband (UWB) antennas with different ground shape having directional radiation pattern is being presented here. Firstly, the L-shape corner reflector ground plane antenna is designed with microstrip feed line in order to achieve large bandwidth and directivity. Thereafter, for the further improvement in the directivity as well as for better impedance matching the parabolic-shape ground plane has been introduced. The coaxial feed line is given for the proposed directional antenna in order to achieve better impedance matching with 50 ohm transmission line. The simulation analysis of the antenna is done on CST Microwave Studio software using FR-4 substrate having thickness of 1.6 mm and dielectric constant of 4.4. The simulated result shows a good return loss (S11) with respect to -10 dB. The radiation pattern characteristic, angular width, directivity and bandwidth performance of the antenna have also been compared at different resonant frequencies. The designed antennas exhibit low cost, low reflection coefficient and better directivity in the UWB frequency band.

  7. Millimeter-Wave Phaseless Antenna Measurement Based on a Modified Off-Axis Holography Setup

    NASA Astrophysics Data System (ADS)

    Arboleya, Ana; Ala-Laurinaho, Juha; Laviada, Jaime; Álvarez, Yuri; Las-Heras, Fernando; Räisänen, Antti V.

    2016-02-01

    A novel scheme for planar near-field phaseless antenna measurement based on off-axis holography is presented. Separation of the image terms of the hologram is artificially increased by multiplexing the measurements of two sub-sampled holograms generated with two 180° phase-shifted reference waves. Combination of both sub-sampled holograms produces replicas of the image terms at half a period distance of the originals in the spectral domain, while the amplitude of the original image terms is highly reduced, easing the filtering process of the desired replica. The higher separation of the image terms reduces overlapping making the method suitable also for the characterization of medium and low gain antennas in the near-field. As the separation is artificially increased, the reference antenna can be placed close to the antenna under test allowing to reduce the scan distance and the sensitivity to scan axis errors. Nevertheless, spatial multiplexing requires the retrieved data to be spatially low-pass filtered to remove the effect of the aliasing. Mirror reflection is used for illuminating the acquisition plane with the reference wave, being the phase shift achieved by means of a mechanical displacement of the mirror. The effect of the location of the reference antenna on the position and shape of the image terms and their replicas has been studied through numerical simulations for a setup in the W-band. Experimental validation of the method is presented for the characterization of three different antennas at 94 GHz.

  8. A liquid metal-based structurally embedded vascular antenna: I. Concept and multiphysical modeling

    NASA Astrophysics Data System (ADS)

    Hartl, D. J.; Frank, G. J.; Huff, G. H.; Baur, J. W.

    2017-02-01

    This work proposes a new concept for a reconfigurable structurally embedded vascular antenna (SEVA). The work builds on ongoing research of structurally embedded microvascular systems in laminated structures for thermal transport and self-healing and on studies of non-toxic liquid metals for reconfigurable electronics. In the example design, liquid metal-filled channels in a laminated composite act as radiating elements for a high-power planar zig-zag wire log periodic dipole antenna. Flow of liquid metal through the channels is used to limit the temperature of the composite in which the antenna is embedded. A multiphysics engineering model of the transmitting antenna is formulated that couples the electromagnetic, fluid, thermal, and mechanical responses. In part 1 of this two-part work, it is shown that the liquid metal antenna is highly reconfigurable in terms of its electromagnetic response and that dissipated thermal energy generated during high power operation can be offset by the action of circulating or cyclically replacing the liquid metal such that heat is continuously removed from the system. In fact, the SEVA can potentially outperform traditional copper-based antennas in high-power operational configurations. The coupled engineering model is implemented in an automated framework and a design of experiment study is performed to quantify first-order design trade-offs in this multifunctional structure. More rigorous design optimization is addressed in part 2.

  9. Design and Development of Aerogel-Based Antennas for Aerospace Applications: A Final Report to the NARI Seedling

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann B.; Miranda, Felix A.

    2014-01-01

    As highly porous solids possessing low density and low dielectric permittivity combined with good mechanical properties, polyimide (PI) aerogels offer great promise as an enabling technology for lightweight aircraft antenna systems. While they have been aggressively explored for thermal insulation, barely any effort has been made to leverage these materials for antennas or other applications that take advantage of their aforementioned attributes. In Phase I of the NARI Seedling Project, we fabricated PI aerogels with properties tailored to enable new antenna concepts with performance characteristics (wide bandwidth and high gain) and material properties (low density, environmental stability, and robustness) superior to the state of practice (SOP). We characterized electromagnetic properties, including permittivity, reflectivity, and propagation losses for the aerogels. Simple, prototype planar printed circuit patch antennas from down-selected aerogel formulations were fabricated by molding the aerogels to net shapes and by gold-metalizing the pattern onto the templates via electron beam evaporation in a clean room environment. These aerogel based antennas were benchmarked against current antenna SOP, and exhibited both broader bandwidth and comparable or higher gain performance at appreciably lower mass. Phase II focused on the success of the Phase I results pushing the PI aerogel based antenna technology further by exploring alternative antenna design (i.e., slot coupled antennas) and by examining other techniques for fabricating the antennas including ink jet printing with the goal of optimizing antenna performance and simplifying production. We also examined new aerogel formulations with better moisture and solvent resistance to survive processing conditions. In addition, we investigated more complex antenna designs including passive phased arrays such as 2x4 and 4x8 element arrays to assess the scalability of the aerogel antenna concept. Furthermore, we

  10. Flying Drosophila stabilize their vision-based velocity controller by sensing wind with their antennae

    PubMed Central

    Fuller, Sawyer Buckminster; Straw, Andrew D.; Peek, Martin Y.; Murray, Richard M.; Dickinson, Michael H.

    2014-01-01

    Flies and other insects use vision to regulate their groundspeed in flight, enabling them to fly in varying wind conditions. Compared with mechanosensory modalities, however, vision requires a long processing delay (~100 ms) that might introduce instability if operated at high gain. Flies also sense air motion with their antennae, but how this is used in flight control is unknown. We manipulated the antennal function of fruit flies by ablating their aristae, forcing them to rely on vision alone to regulate groundspeed. Arista-ablated flies in flight exhibited significantly greater groundspeed variability than intact flies. We then subjected them to a series of controlled impulsive wind gusts delivered by an air piston and experimentally manipulated antennae and visual feedback. The results show that an antenna-mediated response alters wing motion to cause flies to accelerate in the same direction as the gust. This response opposes flying into a headwind, but flies regularly fly upwind. To resolve this discrepancy, we obtained a dynamic model of the fly’s velocity regulator by fitting parameters of candidate models to our experimental data. The model suggests that the groundspeed variability of arista-ablated flies is the result of unstable feedback oscillations caused by the delay and high gain of visual feedback. The antenna response drives active damping with a shorter delay (~20 ms) to stabilize this regulator, in exchange for increasing the effect of rapid wind disturbances. This provides insight into flies’ multimodal sensory feedback architecture and constitutes a previously unknown role for the antennae. PMID:24639532

  11. Citizen Observatories: A Standards Based Architecture

    NASA Astrophysics Data System (ADS)

    Simonis, Ingo

    2015-04-01

    A number of large-scale research projects are currently under way exploring the various components of citizen observatories, e.g. CITI-SENSE (http://www.citi-sense.eu), Citclops (http://citclops.eu), COBWEB (http://cobwebproject.eu), OMNISCIENTIS (http://www.omniscientis.eu), and WeSenseIt (http://www.wesenseit.eu). Common to all projects is the motivation to develop a platform enabling effective participation by citizens in environmental projects, while considering important aspects such as security, privacy, long-term storage and availability, accessibility of raw and processed data and its proper integration into catalogues and international exchange and collaboration systems such as GEOSS or INSPIRE. This paper describes the software architecture implemented for setting up crowdsourcing campaigns using standardized components, interfaces, security features, and distribution capabilities. It illustrates the Citizen Observatory Toolkit, a software suite that allows defining crowdsourcing campaigns, to invite registered and unregistered participants to participate in crowdsourcing campaigns, and to analyze, process, and visualize raw and quality enhanced crowd sourcing data and derived products. The Citizen Observatory Toolkit is not a single software product. Instead, it is a framework of components that are built using internationally adopted standards wherever possible (e.g. OGC standards from Sensor Web Enablement, GeoPackage, and Web Mapping and Processing Services, as well as security and metadata/cataloguing standards), defines profiles of those standards where necessary (e.g. SWE O&M profile, SensorML profile), and implements design decisions based on the motivation to maximize interoperability and reusability of all components. The toolkit contains tools to set up, manage and maintain crowdsourcing campaigns, allows building on-demand apps optimized for the specific sampling focus, supports offline and online sampling modes using modern cell phones with

  12. Miniaturized and reconfigurable notch antenna based on a BST ferroelectric thin film

    SciTech Connect

    Nguyen, Hung Viet; Benzerga, Ratiba; Borderon, Caroline; Delaveaud, Christophe; Sharaiha, Ala; Renoud, Raphael; Paven, Claire Le; Pavy, Sabrina; Nadaud, Kevin; Gundel, Hartmut W.

    2015-07-15

    Highlights: • A miniature and agile antenna based on a BST MIM capacitor is simulated and made. • Mn{sup 2+} doped BST thin films are synthesized by chemical deposition and spin coating. • Permittivity and losses of the BST thin film are respectively 225 and 0.02 at 1 GHz. • A miniaturization rate of 70% is obtained with a MIM capacitance of 3.7 pF. • A frequency tunability of 14.5% and a tunability performance of 0.04 are measured. - Abstract: This work deals with the design, realization and characterization of a miniature and frequency agile antenna based on a ferroelectric Ba{sub 0,80}Sr{sub 0,20}TiO{sub 3} thin film. The notch antenna is loaded with a variable metal/insulator/metal (MIM) capacitor and is achieved by a monolithic method. The MIM capacitance is 3.7 pF, which results in a resonant frequency of 670 MHz compared to 2.25 GHz for the unloaded simulated antenna; the resulting miniaturization rate is 70%. The characterization of the antenna prototype shows a frequency tunable rate of 14.5% under an electric field of 375 kV/cm, with a tunability performance η = 0.04.

  13. Antenna Modeling and Reconstruction Accuracy of Time Domain-Based Image Reconstruction in Microwave Tomography

    PubMed Central

    Padhi, Shantanu K.; Howard, John

    2013-01-01

    Nonlinear microwave imaging heavily relies on an accurate numerical electromagnetic model of the antenna system. The model is used to simulate scattering data that is compared to its measured counterpart in order to reconstruct the image. In this paper an antenna system immersed in water is used to image different canonical objects in order to investigate the implication of modeling errors on the final reconstruction using a time domain-based iterative inverse reconstruction algorithm and three-dimensional FDTD modeling. With the test objects immersed in a background of air and tap water, respectively, we have studied the impact of antenna modeling errors, errors in the modeling of the background media, and made a comparison with a two-dimensional version of the algorithm. In conclusion even small modeling errors in the antennas can significantly alter the reconstructed image. Since the image reconstruction procedure is highly nonlinear general conclusions are very difficult to make. In our case it means that with the antenna system immersed in water and using our present FDTD-based electromagnetic model the imaging results are improved if refraining from modeling the water-wall-air interface and instead just use a homogeneous background of water in the model. PMID:23606825

  14. Bandwidth provisioning in infrastructure-based wireless networks employing directional antennas

    SciTech Connect

    Hasiviswanthan, Shiva; Zhao, Bo; Vasudevan, Sudarshan; Yrgaonkar, Bhuvan

    2009-01-01

    Motivated by the widespread proliferation of wireless networks employing directional antennas, we study the problem of provisioning bandwidth in such networks. Given a set of subscribers and one or more access points possessing directional antennas, we formalize the problem of orienting these antennas in two fundamental settings: (1) subscriber-centric, where the objective is to fairly allocate bandwidth among the subscribers and (2) provider-centric, where the objective is to maximize the revenue generated by satisfying the bandwidth requirements of subscribers. For both the problems, we first design algorithms for a network with only one access point working under the assumption that the number of antennas does not exceed the number of noninterfering channels. Using the well-regarded lexicographic max-min fair allocation as the objective for a subscriber-centric network, we present an optimum dynamic programming algorithm. For a provider-centric network, the allocation problem turns out to be NP-hard. We present a greedy heuristic based algorithm that guarantees almost half of the optimum revenue. We later enhance both these algorithms to operate in more general networks with multiple access points and no restrictions on the relative numbers of antennas and channels. A simulation-based evaluation using OPNET demonstrates the efficacy of our approaches and provides us further in insights into these problems.

  15. Design and Analysis of Miniaturized Microstrip Patch Antenna with Metamaterials Based on Modified Split-Ring Resonator for UWB Applications

    NASA Astrophysics Data System (ADS)

    Khedrouche, D.; Bougoutaia, T.; Hocini, A.

    2016-11-01

    In this paper, a miniaturized microstrip patch antenna using a negative index metamaterial with modified split-ring resonator (SRR) unit cells is proposed for ultra-wideband (UWB) applications. The new design of metamaterial based microstrip patch antenna has been optimized to provide an improved bandwidth and multiple frequency operations. All the antenna performance parameters are presented in response-graphs. Also it is mentioned that the physical dimensions of the metamaterial based patch antenna are very small, which is convenient to modern communication. A 130 % bandwidth, covering the frequency band of 2.9-13.5 GHz, (for return loss less than or equal -10 dB) is achieved, which allow the antenna to operate in the Federal Communication Commission (FCC) band. In addition, the antenna has a good radiation pattern in the ultra-wide band spectrum, and it is nearly omnidirectional.

  16. Antenna pointing system for satellite tracking based on Kalman filtering and model predictive control techniques

    NASA Astrophysics Data System (ADS)

    Souza, André L. G.; Ishihara, João Y.; Ferreira, Henrique C.; Borges, Renato A.; Borges, Geovany A.

    2016-12-01

    The present work proposes a new approach for an antenna pointing system for satellite tracking. Such a system uses the received signal to estimate the beam pointing deviation and then adjusts the antenna pointing. The present work has two contributions. First, the estimation is performed by a Kalman filter based conical scan technique. This technique uses the Kalman filter avoiding the batch estimator and applies a mathematical manipulation avoiding the linearization approximations. Secondly, a control technique based on the model predictive control together with an explicit state feedback solution are obtained in order to reduce the computational burden. Numerical examples illustrate the results.

  17. Simulation-based analysis of performance parameters of microstrip antennas with criss-cross metamaterial-based artificial substrate

    NASA Astrophysics Data System (ADS)

    Inamdar, Kirti; Kosta, Y. P.; Patnaik, S.

    2014-10-01

    In this paper, we present the design of a metamaterial-based microstrip patch antenna, optimized for bandwidth and multiple frequency operations. A criss-cross structure has been proposed, this shape has been inspired from the famous Jerusalem cross. The theory and design formulas to calculate various parameters of the proposed antenna have been presented. Design starts with the analysis of the proposed unit cell structure, and validating the response using software- HFSS Version 13, to obtain negative response of ε and μ- metamaterial. Following this, a metamaterial-based-microstrip-patch-antenna is designed. A detailed comparative study is conducted exploring the response of the designed patch made of metamaterial and that of the conventional patch. Finally, antenna parameters such as gain, bandwidth, radiation pattern, and multiple frequency responses are investigated and optimised for the same and present in table and response graphs. It is also observed that the physical dimension of the metamaterial-based patch antenna is smaller compared to its conventional counterpart operating at the same fundamental frequency. The challenging part was to develop metamaterial based on some signature structures and techniques that would offer advantage in terms of BW and multiple frequency operation, which is demonstrated in this paper. The unique shape proposed in this paper gives improvement in bandwidth without reducing the gain of the antenna.

  18. Comparison of RF Photonics-Based Beamformers for Super-Wide Bandwidth Phased Array Antennas

    NASA Astrophysics Data System (ADS)

    Belkin, M.; Sigov, A.; Tyschuk, Y.; Golovin, V.

    2017-05-01

    We demonstrate the NI AWRDE E-CAD tool-based simulation experiments to compare the three arrangements of photonic beam forming networks. The results confirm clearly the benefits of the proposed arrangement based on combination of multichannel fiber Bragg grating and switchable optical delay lines providing super-wide operating bandwidth and the better economical characteristics of microwave-band phased array antennas.

  19. LC nano composites based patch antenna @ 12 GHz frequency

    NASA Astrophysics Data System (ADS)

    Karim, Afaque; Yadav, Harsh; Hasan, Shakebul; Ahmad, Shakeb

    2016-05-01

    We study the effect of multiferroic Bismuth Ferrite (BFO) nanoparticles dispersed in nematic liquid crystal(NLC) i.e. 4-Cyano-4'-Pentylbiphenyl (5CB) on the orientational ordering at different biasing voltages (At 0V and 2V).The concentration of BFO nanoparticles doped was 0.5Mol% in NLC. Results shows that dielectric parameters are strong function of frequency and applied bias voltage. Moreover, Patch Antenna was designed based on Liquid Crystal (LC) Nanocomposites (LC+0.5 Mol%BFO nanoparticles) for earth and space applications. To fulfill the demand of modern antenna i.e. tunability, we have investigated a design of LC Nanocomposities based patch antenna with optimum frequency of 12 GHz. In this design, BFO nanoparticles dispersed in NLC is used as a dielectric substrate. Its dielectric permittivity is controlled by biasing voltage. Thus one gets tunability or shift in resonant frequency in the proposed geometry.

  20. Spline-based distributed system identification with application to large space antennas

    NASA Technical Reports Server (NTRS)

    Banks, H. T.; Lamm, P. K.; Armstrong, E. S.

    1986-01-01

    A parameter and state estimation technique for distributed models is demonstrated through the solution of a problem generic to large space antenna system identification. Assuming the position of the reflective surface of the maypole (hoop/column) antenna to be approximated by the static two-dimensional, stretched-membrane partial differential equation with variable-stiffness coefficient functions, a spline-based approximation procedure is described that estimates the shape and stiffness functions from data set observations. For given stiffness functions, the Galerkin projection with linear spline-based functions is applied to project the distributed problem onto a finite-dimensional subspace wherein algebraic equations exist for determining a static shape (state) prediction. The stiffness functions are then parameterized by cubic splines and the parameters estimated by an output error technique. Numerical results are presented for data descriptive of a 100-m-diameter maypole antenna.

  1. Spoof surface plasmon-based stripe antennas with extreme field enhancement in the terahertz regime.

    PubMed

    Han, Zhanghua; Zhang, Yusheng; Bozhevolnyi, Sergey I

    2015-06-01

    Retardation-based stripe antennas due to the excitation of spoof surface plasmons on a corrugated metal stripe are proposed and numerically studied in the terahertz regime, revealing sharp Fabry-Perot resonances in scattering cross-section spectra with strongly enhanced local fields. The order of the resonance exhibiting the sharpest scattering cross section and strongest field enhancements (FEs) is found to coincide with the number of grooves, due to the hybridization of the antenna resonance with the individual groove resonance. The proposed (spoof surface plasmon-based) antennas with narrow resonances and large FE open up new possibilities for metamaterial design and seem very promising for sensing applications in the terahertz frequencies.

  2. Spline-based distributed system identification with application to large space antennas

    NASA Technical Reports Server (NTRS)

    Banks, H. T.; Lamm, P. K.; Armstrong, E. S.

    1986-01-01

    A parameter and state estimation technique for distributed models is demonstrated through the solution of a problem generic to large space antenna system identification. Assuming the position of the reflective surface of the maypole (hoop/column) antenna to be approximated by the static two-dimensional, stretched-membrane partial differential equation with variable-stiffness coefficient functions, a spline-based approximation procedure is described that estimates the shape and stiffness functions from data set observations. For given stiffness functions, the Galerkin projection with linear spline-based functions is applied to project the distributed problem onto a finite-dimensional subspace wherein algebraic equations exist for determining a static shape (state) prediction. The stiffness functions are then parameterized by cubic splines and the parameters estimated by an output error technique. Numerical results are presented for data descriptive of a 100-m-diameter maypole antenna.

  3. Metamaterial-based Fabry-Pérot leaky wave antennas: low profile, high directivity, frequency agility and beam steering

    NASA Astrophysics Data System (ADS)

    Burokur, S. N.; de Lustrac, A.

    2013-04-01

    The analysis and design of subwavelength metamaterial-based Fabry-Pérot (FP) leaky wave antennas (LWAs) are presented. The antennas under investigation are formed by embedding a feeding source in a cavity composed of a Perfect Electrical Conductor (PEC) surface and a metasurface reflector. Several configurations of such antennas are presented to achieve different desired performances such as: high directivity, frequency agility and beam steering.

  4. Superconducting antennas for telecommunication applications based on dual mode cross slotted patches

    NASA Astrophysics Data System (ADS)

    Cassinese, A.; Barra, M.; Fragalà, I.; Kusunoki, M.; Malandrino, G.; Nakagawa, T.; Perdicaro, L. M. S.; Sato, K.; Ohshima, S.; Vaglio, R.

    2002-08-01

    Dual mode devices based on high temperature superconducting films represent an interesting class for telecommunication applications since they combine a miniaturized size with a good power handling. Here we report on a novel compact antenna obtained by crossing a square patch with two or more slots. The proposed design has an antenna size reduction of about 40% as compared to the conventional square patch microstrip antennas. Single patch antenna both with linear (LP) and circular (CP) polarization operating in the X-band have been designed and tested at prototype level. They are realized by using double sided (YBa 2Cu 3O 7- x) YBCO and Tl 2Ba 2Ca 1Cu 2O 8 (Tl-2212) superconducting films grown on MgO substrates and tested with a portable cryocooler. They showed at T=77 K a return loss <25 dB and a power handling of 23 dBm. Exemplary 16 elements arrays LP antennas operating in the X band have been also realized by using YBCO film grown on 2 ″ diameter MgO substrate.

  5. A Novel Monopulse Antenna Based on Quasi-Optical Technology at Sub-millimeter Wavelengths

    NASA Astrophysics Data System (ADS)

    Zhang, Long; Dou, Wenbin; Su, Hongyan; Zhang, Xiaojing

    2015-08-01

    In this paper, a novel monopulse antenna operating at sub-millimeter wavelengths is firstly proposed and developed based on quasi-optical (QO) technology. The developed monopulse antenna is composed of spherical thin lens, ellipsoid mirrors, plane mirrors, quasi-optical sum-difference comparator, and dielectric prisms. The parameters of quasi-optical elements are determined by using Gaussian-Beam theory. Then, the antenna configuration is simulated and further optimized by finite-difference time-domain (FDTD) method. The simulated results show good sum-difference performance, with the sidelobe levels below -10.0 dB and the null-depth approximately -35.0 dB at the center frequency of 375 GHz. A prototype of the proposed monopulse antenna is fabricated and measured. The measured results have a good agreement with the simulated results in the near-field test process. This type of QO monopulse antenna may be used as an excellent candidate for tracking system over 300 GHz.

  6. An ultra-wideband pattern reconfigurable antenna based on graphene coating

    NASA Astrophysics Data System (ADS)

    Jiang, YanNan; Yuan, Rui; Gao, Xi; Wang, Jiao; Li, SiMin; Lin, Yi-Yu

    2016-11-01

    An ultra-wideband pattern reconfigurable antenna is proposed. The antenna is a dielectric coaxial hollow monopole with a cylindrical graphene-based impedance surface coating. It consists of a graphene sheet coated onto the inner surface of a cylindrical substrate and a set of independent polysilicon DC gating pads mounted on the outside of the cylindrical substrate. By changing the DC bias voltages to the different gating pads, the surface impedance of the graphene coating can be freely controlled. Due to the tunability of graphene's surface impedance, the radiation pattern of the proposed antenna can be reconfigured. A transmission line method is used to illustrate the physical mechanism of the proposed antenna. The results show that the proposed antenna can reconfigure its radiation pattern in the omnidirectional mode with the relative bandwidth of 58.5% and the directional mode over the entire azimuth plane with the relative bandwidth of 67%. Project supported by the National Natural Science Foundation of China (Grant Nos. 61661012, 61461016, and 61361005), the Natural Science Foundation of Guangxi, China (Grant Nos. 2015GXNSFBB139003 and 2014GXNSFAA118283), Program for Innovation Research Team of Guilin University of Electromagnetic Technology, China, and the Dean Project of Guangxi Key Laboratory of Wireless Wideband Communication and Signal Processing, China.

  7. Research on field of view of optical receiving antenna based on indoor visible light communication system

    NASA Astrophysics Data System (ADS)

    Gao, Mingguang; Lan, Tian; Zhao, Tao; Zhang, Yilun; Cui, Zhenghua; Ni, Guoqiang

    2015-08-01

    Optical receiving antenna is usually positioned before the detector of an indoor visible light communication (VLC) system in order to collect more optical energy into the detector. Besides optical gain of the antenna, the field of view (FOV) plays also an important role to the performance of a VLC system. In this paper, the signal noise ratio (SNR) and inter-symbol interference (ISI) versus FOV of the antenna are simulated via Line-of-Sight (LOS) and non-Line-of-Sight (NLOS) links within a room with a size of 5m × 5m × 3m. Results show that, the blind area appears while the FOV is less than 40 deg. and the SNR reduces as FOV increases and keeps small when FOV is more than 70 deg.. Furthermore, the average power of ISI rises with the increase of FOV, and the rising trend is relatively moderate when FOV is below 50 deg., while there is a rapid increase between 50 deg. and 70 deg. and finally tends to be stable after 70 deg. Therefore, it is practical to determine the FOV of the optical receiving antenna in the scope of 40 to 50 deg. based on the installment of LED lights on the ceiling here so as to avoid the blind area, attain high SNR, and reduce the influence of ISI. It is also worthwhile in practice to provide an identifiable evidence for the determination of FOV of the optical antenna.

  8. Meander-line-based inhomogeneous anisotropic artificial material for gain enhancement of UWB Vivaldi antenna

    NASA Astrophysics Data System (ADS)

    Pandey, Gaurav Kumar; Singh, Hari Shankar; Meshram, Manoj Kumar

    2016-02-01

    An inhomogeneous anisotropic (IA) artificial material (AM) is proposed having epsilon-near-zero (ENZ) characteristics and effective refractive index >1, simultaneously, in the same direction. Further, the proposed IA-AM is utilized for the gain enhancement of Vivaldi antenna for ultra-wideband (UWB) applications. The IA-AM consists of two types of compact meandered line-based anisotropic artificial material with ENZ characteristics in two adjacent narrow bands of 5.5-8.5 and 8-11.5 GHz. However, the non-resonant behavior of the artificial material in other direction appears with high refractive index property in broadband region. The combination of both the unit cells with broadband ENZ and high refractive index property is used to improve the gain of the Vivaldi antenna in broadband. The proposed IA-AM-loaded Vivaldi antenna exhibits a gain enhancement of up to 2 dBi compared to the original antenna in the operating frequency band of 3.1-12 GHz with | S 11| < -10 dB. The proposed antenna shows nearly stable unidirectional radiation patterns with high directivity and nearly flat group delay.

  9. Ultra-Small Dualband Dualmode Microstrip Antenna Based on Novel Hybrid Resonator

    NASA Astrophysics Data System (ADS)

    Zhu, Ji-Xu; Bai, Peng; Zheng, Hao-Zhong

    2016-11-01

    A novel hybrid resonator consists of right handed patch+composite right and left handed transmission line (RH+CRLH) is proposed for the first time aiming at both compactness and frequency manipulation. A demonstration with theoretical dispersion relations and EM simulation is provided for the correctness and efficiency. According to the new method, an ultra-small and dualband antenna operating around 2.4 GHz (n=0, Bluetooth band) and 3.5 GHz (n=+1, Wimax band) is designed, fabricated and measured, whose occupied area is only of 0.158 λ_0. Numerical and experimental results indicate that the antenna exhibits a good impendence match, low cross-polarization and comparable radiation gains in both bands. Excellent performances of the antennas based on hybrid resonators predict promising applications in multifunction wireless communication systems.

  10. MEMS-based electrostatically tunable microstrip patch antenna using flexible polyimide film

    NASA Astrophysics Data System (ADS)

    Goteti, Raghav Venkat; Ramadoss, Ramesh

    2005-05-01

    This paper reports a MEMS-based electrostatically tunable microstrip patch antenna fabricated using printed circuit processing techniques. The microstrip patch is patterned on the top side of the flexible kapton polyimide film, which is suspended above the fixed ground plane using a spacer. The air gap between the microstrip patch and the ground plane is decreased by applying a DC bias voltage between the patch and the ground plane. A decrease in air gap increases the effective permittivity of the antenna resulting in a downward shift in the resonant frequency. The microstrip patch is excited by a slot in the ground plane, which is inductively coupled by a coplanar waveguide (CPW) feed line. A 6 mm x 6 mm microstrip patch antenna tunable from 18.34 GHz at 0 V to 17.95 GHz at 268 V (with a tuning range of 390 MHz) is discussed.

  11. All-metamaterial-based subwavelength cavities (λ/60) for ultrathin directive antennas

    NASA Astrophysics Data System (ADS)

    Ourir, Abdelwaheb; de Lustrac, André; Lourtioz, Jean-Michel

    2006-02-01

    In this letter, we present the characterization and modeling of a metamaterial-based resonant cavity for ultrathin directive printed antennas. A planar artificial magnetic conductor is used for the two reflectors of the Fabry-Pérot-type resonant cavity. One reflector behaves as a high impedance surface, and serves as a substrate for the printed antenna. The other reflector is a partially reflective surface used as a transmitting window. The cavity is operated on subwavelength modes, the smallest cavity thickness being of the order of λ /60. A drastic enhancement of the antenna directivity and gain is obtained over a relatively wide band from 7.5to10.1GHz, corresponding to a range of cavity thicknesses from ˜λ/3 to ˜λ/60. The cavity resonance is seen to be correctly predicted from the standard ray theory approach.

  12. Analysis of the effect of mobile phone base station antenna loading on localized SAR and its consequences for measurements.

    PubMed

    Hansson, Björn; Thors, Björn; Törnevik, Christer

    2011-12-01

    In this work, the effect of antenna element loading on the localized specific absorption rate (SAR) has been analyzed for base station antennas. The analysis was conducted in order to determine whether localized SAR measurements of large multi-element base station antennas can be conducted using standardized procedures and commercially available equipment. More specifically, it was investigated if the antenna shifting measurement procedure, specified in the European base station exposure assessment standard EN 50383, will produce accurate localized SAR results for base station antennas larger than the specified measurement phantom. The obtained results show that SAR accuracy is affected by the presence of lossy material within distances of one wavelength from the tested antennas as a consequence of coupling and redistribution of transmitted power among the antenna elements. It was also found that the existing standardized phantom is not optimal for SAR measurements of large base station antennas. A new methodology is instead proposed based on a larger, box-shaped, whole-body phantom.

  13. Antenna Autocalibration and Metrology Approach for the AFR/JPL Space-Based Radar

    NASA Technical Reports Server (NTRS)

    McWatters, Dalia; Michel, Thierry; Freedman, Adam; Cable, Vaughn

    2003-01-01

    The Air Force Research Laboratory (AFRL) and the Jet Propulsion Laboratory (JPL) are collaborating in the technology development for a space based radar (SBR) system that would feature a large aperture lightweight antenna for a joint mission later in this decade.

  14. Threshold-Based OSIC Detection Algorithm for Per-Antenna-Coded TIMO-OFDM Systems

    NASA Astrophysics Data System (ADS)

    Wang, Xinzheng; Chen, Ming; Zhu, Pengcheng

    Threshold-based ordered successive interference cancellation (OSIC) detection algorithm is proposed for per-antenna-coded (PAC) two-input multiple-output (TIMO) orthogonal frequency division multiplexing (OFDM) systems. Successive interference cancellation (SIC) is performed selectively according to channel conditions. Compared with the conventional OSIC algorithm, the proposed algorithm reduces the complexity significantly with only a slight performance degradation.

  15. Model-Drive Architecture for Agent-Based Systems

    NASA Technical Reports Server (NTRS)

    Gradanin, Denis; Singh, H. Lally; Bohner, Shawn A.; Hinchey, Michael G.

    2004-01-01

    The Model Driven Architecture (MDA) approach uses a platform-independent model to define system functionality, or requirements, using some specification language. The requirements are then translated to a platform-specific model for implementation. An agent architecture based on the human cognitive model of planning, the Cognitive Agent Architecture (Cougaar) is selected for the implementation platform. The resulting Cougaar MDA prescribes certain kinds of models to be used, how those models may be prepared and the relationships of the different kinds of models. Using the existing Cougaar architecture, the level of application composition is elevated from individual components to domain level model specifications in order to generate software artifacts. The software artifacts generation is based on a metamodel. Each component maps to a UML structured component which is then converted into multiple artifacts: Cougaar/Java code, documentation, and test cases.

  16. Galileo mission planning for Low Gain Antenna based operations

    NASA Technical Reports Server (NTRS)

    Gershman, R.; Buxbaum, K. L.; Ludwinski, J. M.; Paczkowski, B. G.

    1994-01-01

    The Galileo mission operations concept is undergoing substantial redesign, necessitated by the deployment failure of the High Gain Antenna, while the spacecraft is on its way to Jupiter. The new design applies state-of-the-art technology and processes to increase the telemetry rate available through the Low Gain Antenna and to increase the information density of the telemetry. This paper describes the mission planning process being developed as part of this redesign. Principal topics include a brief description of the new mission concept and anticipated science return (these have been covered more extensively in earlier papers), identification of key drivers on the mission planning process, a description of the process and its implementation schedule, a discussion of the application of automated mission planning tool to the process, and a status report on mission planning work to date. Galileo enhancements include extensive reprogramming of on-board computers and substantial hard ware and software upgrades for the Deep Space Network (DSN). The principal mode of operation will be onboard recording of science data followed by extended playback periods. A variety of techniques will be used to compress and edit the data both before recording and during playback. A highly-compressed real-time science data stream will also be important. The telemetry rate will be increased using advanced coding techniques and advanced receivers. Galileo mission planning for orbital operations now involves partitioning of several scarce resources. Particularly difficult are division of the telemetry among the many users (eleven instruments, radio science, engineering monitoring, and navigation) and allocation of space on the tape recorder at each of the ten satellite encounters. The planning process is complicated by uncertainty in forecast performance of the DSN modifications and the non-deterministic nature of the new data compression schemes. Key mission planning steps include

  17. Quantum-dot based ultrafast photoconductive antennae for efficient THz radiation

    NASA Astrophysics Data System (ADS)

    Gorodetsky, Andrei; Bazieva, Natalia; Rafailov, Edik U.

    2016-03-01

    Here we overview our work on quantum dot based THz photoconductive antennae, capable of being pumped at very high optical intensities of higher than 1W optical mean power, i.e. about 50 times higher than the conventional LT-GaAs based antennae. Apart from high thermal tolerance, defect-free GaAs crystal layers in an InAs:GaAs quantum dot structure allow high carrier mobility and ultra-short photo carrier lifetimes simultaneously. Thus, they combine the advantages and lacking the disadvantages of GaAs and LT-GaAs, which are the most popular materials so far, and thus can be used for both CW and pulsed THz generation. By changing quantum dot size, composition, density of dots and number of quantum dot layers, the optoelectronic properties of the overall structure can be set over a reasonable range-compact semiconductor pump lasers that operate at wavelengths in the region of 1.0 μm to 1.3 μm can be used. InAs:GaAs quantum dot-based antennae samples show no saturation in pulsed THz generation for all average pump powers up to 1W focused into 30 μm spot. Generated THz power is super-linearly proportional to laser pump power. The generated THz spectrum depends on antenna design and can cover from 150 GHz up to 1.5 THz.

  18. Computer Program for Thin Wire Antenna over a Perfectly Conducting Ground Plane. [using Galerkins method and sinusoidal bases

    NASA Technical Reports Server (NTRS)

    Richmond, J. H.

    1974-01-01

    A computer program is presented for a thin-wire antenna over a perfect ground plane. The analysis is performed in the frequency domain, and the exterior medium is free space. The antenna may have finite conductivity and lumped loads. The output data includes the current distribution, impedance, radiation efficiency, and gain. The program uses sinusoidal bases and Galerkin's method.

  19. A Miniaturized Antenna with Negative Index Metamaterial Based on Modified SRR and CLS Unit Cell for UWB Microwave Imaging Applications

    PubMed Central

    Islam, Md. Moinul; Islam, Mohammad Tariqul; Samsuzzaman, Md.; Faruque, Mohammad Rashed Iqbal; Misran, Norbahiah; Mansor, Mohd Fais

    2015-01-01

    A miniaturized antenna employing a negative index metamaterial with modified split-ring resonator (SRR) and capacitance-loaded strip (CLS) unit cells is presented for Ultra wideband (UWB) microwave imaging applications. Four left-handed (LH) metamaterial (MTM) unit cells are located along one axis of the antenna as the radiating element. Each left-handed metamaterial unit cell combines a modified split-ring resonator (SRR) with a capacitance-loaded strip (CLS) to obtain a design architecture that simultaneously exhibits both negative permittivity and negative permeability, which ensures a stable negative refractive index to improve the antenna performance for microwave imaging. The antenna structure, with dimension of 16 × 21 × 1.6 mm3, is printed on a low dielectric FR4 material with a slotted ground plane and a microstrip feed. The measured reflection coefficient demonstrates that this antenna attains 114.5% bandwidth covering the frequency band of 3.4–12.5 GHz for a voltage standing wave ratio of less than 2 with a maximum gain of 5.16 dBi at 10.15 GHz. There is a stable harmony between the simulated and measured results that indicate improved nearly omni-directional radiation characteristics within the operational frequency band. The stable surface current distribution, negative refractive index characteristic, considerable gain and radiation properties make this proposed negative index metamaterial antenna optimal for UWB microwave imaging applications. PMID:28787945

  20. A Miniaturized Antenna with Negative Index Metamaterial Based on Modified SRR and CLS Unit Cell for UWB Microwave Imaging Applications.

    PubMed

    Islam, Md Moinul; Islam, Mohammad Tariqul; Samsuzzaman, Md; Faruque, Mohammad Rashed Iqbal; Misran, Norbahiah; Mansor, Mohd Fais

    2015-01-23

    A miniaturized antenna employing a negative index metamaterial with modified split-ring resonator (SRR) and capacitance-loaded strip (CLS) unit cells is presented for Ultra wideband (UWB) microwave imaging applications. Four left-handed (LH) metamaterial (MTM) unit cells are located along one axis of the antenna as the radiating element. Each left-handed metamaterial unit cell combines a modified split-ring resonator (SRR) with a capacitance-loaded strip (CLS) to obtain a design architecture that simultaneously exhibits both negative permittivity and negative permeability, which ensures a stable negative refractive index to improve the antenna performance for microwave imaging. The antenna structure, with dimension of 16 × 21 × 1.6 mm³, is printed on a low dielectric FR4 material with a slotted ground plane and a microstrip feed. The measured reflection coefficient demonstrates that this antenna attains 114.5% bandwidth covering the frequency band of 3.4-12.5 GHz for a voltage standing wave ratio of less than 2 with a maximum gain of 5.16 dBi at 10.15 GHz. There is a stable harmony between the simulated and measured results that indicate improved nearly omni-directional radiation characteristics within the operational frequency band. The stable surface current distribution, negative refractive index characteristic, considerable gain and radiation properties make this proposed negative index metamaterial antenna optimal for UWB microwave imaging applications.

  1. An intelligent service-based network architecture for wearable robots.

    PubMed

    Lee, Ka Keung; Zhang, Ping; Xu, Yangsheng; Liang, Bin

    2004-08-01

    We are developing a novel robot concept called the wearable robot. Wearable robots are mobile information devices capable of supporting remote communication and intelligent interaction between networked entities. In this paper, we explore the possible functions of such a robotic network and will present a distributed network architecture based on service components. In order to support the interaction and communication between the components in the wearable robot system, we have developed an intelligent network architecture. This service-based architecture involves three major mechanisms. The first mechanism involves the use of a task coordinator service such that the execution of the services can be managed using a priority queue. The second mechanism enables the system to automatically push the required service proxy to the client intelligently based on certain system-related conditions. In the third mechanism, we allow the system to automatically deliver services based on contextual information. Using a fuzzy-logic-based decision making system, the matching service can determine whether the service should be automatically delivered utilizing the information provided by the service, client, lookup service, and context sensors. An application scenario has been implemented to demonstrate the feasibility of this distributed service-based robot architecture. The architecture is implemented as extensions to the Jini network model.

  2. Progress in Arc Safety System Based on Harmonics Detection for ICRH Antennae

    SciTech Connect

    Berger-By, G.; Beaumont, B.; Lombard, G.; Millon, L.; Mollard, P.; Volpe, D.

    2007-09-28

    The arc detection systems based on harmonics detection have been tested n USA (TFTR, DIII, Alcator C-mod) and Germany (Asdex). These systems have some advantages in comparison with traditonal securities which use a threshold on the Vr/Vf (Reflected to Forward voltage ratio) calculation and are ITER relevant. On Tore Supra (TS) 3 systems have been built using this principle with some improvements and new features to increase the protection of the 3 ICRH generators and antennae. On JET 2 arc safety systems based on the TS principle wil also be used to mprove the JET ITER-like antenna safety. In order to have the maximum security level on the TS ICRH system, the 3 antennae are used with these systems during all plasma shots n redundancy with the other systems. This TS RF principle and ts electronic interactions with the VME control of the generator are described. The results on the TS ICRH transmitter feeding the 3 antennae are summarized and some typical signals are given.

  3. Directive metamaterial-based subwavelength resonant cavity antennas - Applications for beam steering

    NASA Astrophysics Data System (ADS)

    Ourir, Abdelwaheb; Burokur, Shah Nawaz; Yahiaoui, Riad; de Lustrac, André

    2009-06-01

    This article presents the use of composite resonant metamaterials for the design of highly directive subwavelength cavity antennas. These metamaterials, composed of planar metallic patterns periodically organized on dielectric substrates, exhibit frequency dispersive phase characteristics. Different models of metamaterial-based surfaces (metasurfaces), introducing a zero degree reflection phase shift to incident waves, are firstly studied where the bandwidth and operation frequency are predicted. These surfaces are then applied in a resonant Fabry-Perot type cavity and a ray optics analysis is used to design different models of ultra-compact high-gain microstrip printed antennas. Another surface presenting a variable reflection phase by the use of a non-periodic metamaterial-based metallic strips array is designed for a passive low-profile steering beam antenna application. Finally, the incorporation of active electronic components on the metasurfaces, allowing an electronic control of the phase responses, is applied to an operation frequency reconfigurable cavity and a beam steering cavity. All these cavity antennas operate on subwavelength modes, the smallest cavity thickness being of the order of λ/60. To cite this article: A. Ourir et al., C. R. Physique 10 (2009).

  4. Analysis of single band and dual band graphene based patch antenna for terahertz region

    NASA Astrophysics Data System (ADS)

    George, Jemima Nissiyah; Madhan, M. Ganesh

    2017-10-01

    A microstrip patch antenna is designed using a very thin layer of graphene as the radiating patch, which is fed by a microstrip transmission line. The graphene based patch is designed on a silicon substrate having a dielectric constant of 11.9, to radiate at a single frequency of 2.6 THz. Further, this antenna is made to resonate at dual frequencies of 2.48 THz and 3.35 THz, by changing the substrate height, which is reported for the first time. Various antenna parameters such as return loss, VSWR, gain, efficiency and bandwidth are also determined for the single and dual band operation. For the single band operation, a bandwidth of 145.4 GHz and an efficiency of 92% was achieved. For dual band operation, a maximum bandwidth of 140.5 GHz was obtained at 3.35 THz and an efficiency of 87.3% was obtained at the first resonant frequency of 2.48 THz. The absorption cross section of the antenna is also analysed for various substrate heights and has maximum peaks at the corresponding resonating frequencies. The simulation has been carried out by using a full wave electromagnetic simulator based on FDTD method.

  5. Sensitivity Enhanced Vital Sign Detection Based on Antenna Reflection Coefficient Variation.

    PubMed

    An, Yong-Jun; Yun, Gi-Ho; Yook, Jong-Gwan

    2016-04-01

    This paper presents a vital sign detection sensor based on reflection coefficient variance from an antenna used in wireless communication devices. The near-field effect is estimated by performing 3D full-wave simulations using a dipole antenna and the magnitude variation of the reflection coefficient induced by human thorax movement due to heart and lungs is observed. The results support the possibility of vital sign detection based on the magnitude variation of the reflection coefficient from an antenna, which can be explained as a narrowband modulation scheme. In particular, a sensitivity enhancement method is proposed and analyzed, and experiments are carried out for heartbeat detection using a dipole antenna with the proposed system. Experimental results are compared between the direct detection and sensitivity enhancement detection schemes. FM signal is also applied to confirm that the proposed sensor works properly in conjunction with an existing communication system. The proposed cardiopulmonary detection sensor is implemented with off-the-shelf components at 2.4 GHz and excellent performance is obtained.

  6. Planetary gearbox condition monitoring of ship-based satellite communication antennas using ensemble multiwavelet analysis method

    NASA Astrophysics Data System (ADS)

    Chen, Jinglong; Zhang, Chunlin; Zhang, Xiaoyan; Zi, Yanyang; He, Shuilong; Yang, Zhe

    2015-03-01

    Satellite communication antennas are key devices of a measurement ship to support voice, data, fax and video integration services. Condition monitoring of mechanical equipment from the vibration measurement data is significant for guaranteeing safe operation and avoiding the unscheduled breakdown. So, condition monitoring system for ship-based satellite communication antennas is designed and developed. Planetary gearboxes play an important role in the transmission train of satellite communication antenna. However, condition monitoring of planetary gearbox still faces challenges due to complexity and weak condition feature. This paper provides a possibility for planetary gearbox condition monitoring by proposing ensemble a multiwavelet analysis method. Benefit from the property on multi-resolution analysis and the multiple wavelet basis functions, multiwavelet has the advantage over characterizing the non-stationary signal. In order to realize the accurate detection of the condition feature and multi-resolution analysis in the whole frequency band, adaptive multiwavelet basis function is constructed via increasing multiplicity and then vibration signal is processed by the ensemble multiwavelet transform. Finally, normalized ensemble multiwavelet transform information entropy is computed to describe the condition of planetary gearbox. The effectiveness of proposed method is first validated through condition monitoring of experimental planetary gearbox. Then this method is used for planetary gearbox condition monitoring of ship-based satellite communication antennas and the results support its feasibility.

  7. Cross resonant optical antenna.

    PubMed

    Biagioni, P; Huang, J S; Duò, L; Finazzi, M; Hecht, B

    2009-06-26

    We propose a novel cross resonant optical antenna consisting of two perpendicular nanosized gold dipole antennas with a common feed gap. We demonstrate that the cross antenna is able to convert propagating fields of any polarization state into correspondingly polarized, localized, and enhanced fields and vice versa. The cross antenna structure therefore opens the road towards the control of light-matter interactions based on polarized light as well as the analysis of polarized fields on the nanometer scale.

  8. A linearly and circularly polarized active integrated antenna

    NASA Astrophysics Data System (ADS)

    Khoshniat, Ali

    This thesis work presents a new harmonic suppression technique for microstrip patch antennas. Harmonic suppression in active integrated antennas is known as an effective method to improve the efficiency of amplifiers in transmitter side. In the proposed design, the antenna works as the radiating element and, at the same time, as the tuning load for the amplifier circuit that is directly matched to the antenna. The proposed active antenna architecture is easy to fabricate and is symmetric, so it can be conveniently mass-produced and designed to have circular polarization, which is preferred in many applications such as satellite communications. The antenna simulations were performed using Ansoft High Frequency System Simulator (HFSS) and all amplifier design steps were simulated by Advanced Design System (ADS). The final prototypes of the linearly polarized active integrated antenna and the circularly polarized active integrated antenna were fabricated using a circuit board milling machine. The antenna radiation pattern was measured inside Utah State University's anechoic chamber and the results were satisfactory. Power measurements for the amplifiers' performance were carried out inside the chamber and calculated by using the Friis transmission equation. It is seen that a significant improvement in the efficiency is achieved compared to the reference antenna without harmonic suppression. Based on the success in the single element active antenna design, the thesis also presents a feasibility of applying the active integrated antenna in array configuration, in particular, in scanning array design to yield a low-profile, low-cost alternative to the parabolic antenna transmitter of satellite communication systems.

  9. Miniaturized Antennas and Metamaterial-Based Transmission Line Components in Microwave Circuits Applications

    NASA Astrophysics Data System (ADS)

    Chi, Pei-Ling

    This dissertation presents two diversities of miniaturization approaches to the antennas and microwave passive circuit components. The first approach is based on the unique metamaterial transmission line structures. The metamaterial structure or the left-handed structure is an artificial structure that is dispersion engineerable from its constituent parameters. By means of the left-handed transmission lines or the composite right/left-handed (CRLH) transmission lines to replace the conventional microstrip lines, microwave circuit components can be miniaturized via controlling the phase responses at the frequencies of interest, which saves the footprint size. Specifically, this idea was implemented on the dual-band 180°0 and 90° hybrid couplers and both of them demonstrate considerable size reductions in the experiments. On the other hand, the second methodology leading to miniaturization is taking advantage of the slow wave structures. The slow wave structures presented in this dissertation are formed using the capacitive loading periodically. The effective propagation constant beta is enhanced by increasing the effective shunt capacitance in the equivalent circuit model derived from the conventional transmission line theory. The associated guided wavelength is therefore decreased and the same physical structure is capable of operating at lower frequencies. The slow wave structures are employed for compact antenna applications. In particular, the slow wave enhancement factor (SWE), which is defined as the ratio of the loaded to the unloaded propagation constants (beta//beta), is investigated using the loaded unit cell of the equivalent transmission line model and utilized as a design tool for an arbitrary size reduction. It is shown that the SWE agrees very well with miniaturization factor, and therefore load parameters in the circuit model can be readily obtained when a specific size reduction is attempted. Slow wave antennas will be exemplified in the third

  10. Modeling the Europa Pathfinder avionics system with a model based avionics architecture tool

    NASA Technical Reports Server (NTRS)

    Chau, S.; Traylor, M.; Hall, R.; Whitfield, A.

    2002-01-01

    In order to shorten the avionics architecture development time, the Jet Propulsion Laboratory has developed a model-based architecture simultion tool called the Avionics System Architecture Tool (ASAT).

  11. Artificial magnetic conductor-based circularly polarized crossed-dipole antennas: 2. AMC structure without grounding pins

    NASA Astrophysics Data System (ADS)

    Ta, Son Xuat; Park, Ikmo

    2017-05-01

    This paper is the second part of our study that investigates surface wave resonances on artificial magnetic conductor (AMC)-based circularly polarized (CP) crossed-dipole antennas. In this part, the AMC structure without grounding pins is employed in the antenna system instead of the structure with grounding pins in the first part. Similar to the case with pins, the excitation of surface waves propagating on the finite-sized AMC surface without pins generates extra resonances and CP radiations for the antenna system. These extra resonances and corresponding CP radiations can be used to enhance the impedance matching and axial ratio bandwidths of the antenna, respectively. In addition, surface wave resonances on AMC-based antennas with/without grounding pins are discussed in section 5 of this paper.

  12. Tailoring the chirality of light emission with spherical Si-based antennas

    NASA Astrophysics Data System (ADS)

    Zambrana-Puyalto, Xavier; Bonod, Nicolas

    2016-05-01

    Chirality of light is of fundamental importance in several enabling technologies with growing applications in life sciences, chemistry and photodetection. Recently, some attention has been focused on chiral quantum emitters. Consequently, optical antennas which are able to tailor the chirality of light emission are needed. Spherical nanoresonators such as colloids are of particular interest to design optical antennas since they can be synthesized at a large scale and they exhibit good optical properties. Here, we show that these colloids can be used to tailor the chirality of a chiral emitter. To this purpose, we derive an analytic formalism to model the interaction between a chiral emitter and a spherical resonator. We then compare the performances of metallic and dielectric spherical antennas to tailor the chirality of light emission. It is seen that, due to their strong electric dipolar response, metallic spherical nanoparticles spoil the chirality of light emission by yielding achiral fields. In contrast, thanks to the combined excitation of electric and magnetic modes, dielectric Si-based particles feature the ability to inhibit or to boost the chirality of light emission. Finally, it is shown that dual modes in dielectric antennas preserve the chirality of light emission.

  13. Tailoring the chirality of light emission with spherical Si-based antennas.

    PubMed

    Zambrana-Puyalto, Xavier; Bonod, Nicolas

    2016-05-21

    Chirality of light is of fundamental importance in several enabling technologies with growing applications in life sciences, chemistry and photodetection. Recently, some attention has been focused on chiral quantum emitters. Consequently, optical antennas which are able to tailor the chirality of light emission are needed. Spherical nanoresonators such as colloids are of particular interest to design optical antennas since they can be synthesized at a large scale and they exhibit good optical properties. Here, we show that these colloids can be used to tailor the chirality of a chiral emitter. To this purpose, we derive an analytic formalism to model the interaction between a chiral emitter and a spherical resonator. We then compare the performances of metallic and dielectric spherical antennas to tailor the chirality of light emission. It is seen that, due to their strong electric dipolar response, metallic spherical nanoparticles spoil the chirality of light emission by yielding achiral fields. In contrast, thanks to the combined excitation of electric and magnetic modes, dielectric Si-based particles feature the ability to inhibit or to boost the chirality of light emission. Finally, it is shown that dual modes in dielectric antennas preserve the chirality of light emission.

  14. A Horn-fed Frequency Scanning Holographic Antenna Based on Generalized Law of Reflection.

    PubMed

    Liu, Dawei; Cheng, Bo; Pan, Xiaotian; Qiao, Lifang

    2016-08-12

    A new method of designing horn-fed frequency scanning holographic antenna is proposed. The artificial surface design of holographic antenna is based on generalized law of reflection. The input admittance is utilized to construct the interference pattern of the surface which is intervened by the excitation wave and the required radiation wave. The scalar admittance unit cell which is composed of sub-wavelength metallic patch on grounded dielectric substrate is implemented to design artificial surface, and the simulation results are just as expected that the antenna can scan the beam as the frequency changes. Furthermore, a cross shaped patch printed on grounded dielectric unit cells is used to reduce the designing complexity of tensor admittance surface. At last, a frequency scanning holographic antenna with tensor admittance surface with ability of changing linear polarization excitation wave to left-hand circular polarization (LCP) radiation wave is designed and fabricated. The full-wave simulation and experimental results show well agreement and confirm the method proposed.

  15. A Horn-fed Frequency Scanning Holographic Antenna Based on Generalized Law of Reflection

    PubMed Central

    Liu, Dawei; Cheng, Bo; Pan, Xiaotian; Qiao, Lifang

    2016-01-01

    A new method of designing horn-fed frequency scanning holographic antenna is proposed. The artificial surface design of holographic antenna is based on generalized law of reflection. The input admittance is utilized to construct the interference pattern of the surface which is intervened by the excitation wave and the required radiation wave. The scalar admittance unit cell which is composed of sub-wavelength metallic patch on grounded dielectric substrate is implemented to design artificial surface, and the simulation results are just as expected that the antenna can scan the beam as the frequency changes. Furthermore, a cross shaped patch printed on grounded dielectric unit cells is used to reduce the designing complexity of tensor admittance surface. At last, a frequency scanning holographic antenna with tensor admittance surface with ability of changing linear polarization excitation wave to left-hand circular polarization (LCP) radiation wave is designed and fabricated. The full-wave simulation and experimental results show well agreement and confirm the method proposed. PMID:27515782

  16. Component based open middleware architecture for autonomous navigation system

    NASA Astrophysics Data System (ADS)

    Ahn, Myung Kil; Park, Yong Woon; Jee, Tae Young

    2007-04-01

    This paper introduces component based open middleware architecture implemented by ADD(Agency for Defense Development) to accommodate new technology evolution of unmanned autonomous system. The proposed open system architecture can be considered as a standard interface which defines the messages and operations between software components on application layer level, and its purpose is to ensure the portability of future technology onto multi-platforms as well as the inter-operability domains. In this architecture, the domain is defined as the space where several different robots are operated, and each robot is defined as a subsystem within the domain. Each subsystem, i.e., robot, is composed of several nodes, and then each node is composed of various components including node manager and communicator. The implemented middleware uses reference architecture from JAUS (Joint Architecture for Unmanned System) as a guidance. Among the key achievements of this research is the development of general node manager which makes it possible to easily accommodate a new interface or the new core technology developed on the application layer by providing a platform-independent communication interface between each subsystem and the components. This paper introduces reference architecture and middleware applied in XAV (eXperimental Autonomous Vehicle) developed in ADD. In addition, the performance of autonomous navigation and system design characteristics are briefly introduced.

  17. A liquid metal-based structurally embedded vascular antenna: II. Multiobjective and parameterized design exploration

    NASA Astrophysics Data System (ADS)

    Hartl, D. J.; Frank, G. J.; Malak, R. J.; Baur, J. W.

    2017-02-01

    Research on the structurally embedded vascular antenna concept leverages past efforts on liquid metal (LM) reconfigurable electronics, microvascular composites, and structurally integrated and reconfigurable antennas. Such a concept has potential for reducing system weight or volume while simultaneously allowing in situ adjustment of resonant frequencies and/or changes in antenna directivity. This work considers a microvascular pattern embedded in a laminated composite and filled with LM. The conductive liquid provides radio frequency (RF) functionality while also allowing self-cooling. Models describing RF propagation and heat transfer, in addition to the structural effects of both the inclusion of channels and changes in temperature, were described in part 1 of this two-part work. In this part 2, the engineering models developed and demonstrated in part 1 toward the initial exploration of design trends are implemented into multiple optimization frameworks for more detailed design studies, one of which being novel and particularly applicable to this class of problem. The computational expense associated with the coupled multiphysical analysis of the structurally embedded LM transmitting antenna motivates the consideration of surrogate-based optimization methods. Both static and adaptive approaches are explored; it is shown that iteratively correcting the surrogate leads to more accurate optimized design predictions. The expected strong dependence of antenna performance on thermal environment motivates the consideration of a novel ‘parameterized’ optimization approach that simultaneously calculates whole families of optimal designs based on changes in design or operational variables generally beyond the control of the designer. The change in Pareto-optimal response with evolution in operating conditions is clearly demonstrated.

  18. A neurocomputer based on an analog-digital hybrid architecture

    NASA Technical Reports Server (NTRS)

    Moopenn, A.; Thakoor, A. P.; Duong, T.; Khanna, S. K.

    1987-01-01

    A novel analog-digital hybrid architecture based on the utilization of high density digital random access memories for the storage of the synaptic weights of a neural network, and high speed analog hardware to perform neural computation is described. An electronic neurocomputer based on such an architecture is ideally suited for investigating the dynamics, associative recall properties, and computational capabilities of neural networks and provides significant speed improvement in comparison to conventional software based neural network simulations. As a demonstration of the feasibility of the hybrid architectural concept, a prototype breadboard hybrid neurocomputer system with 32 neurons has been designed and fabricated with off-the-shelf hardware components. The performance of the breadboard system has been tested for variety of applications including associative memory and combinatorial problem solving such as Graph Coloring, and is discussed in this paper.

  19. Electromagnetic Vortex-Based Radar Imaging Using a Single Receiving Antenna: Theory and Experimental Results.

    PubMed

    Yuan, Tiezhu; Wang, Hongqiang; Cheng, Yongqiang; Qin, Yuliang

    2017-03-19

    Radar imaging based on electromagnetic vortex can achieve azimuth resolution without relative motion. The present paper investigates this imaging technique with the use of a single receiving antenna through theoretical analysis and experimental results. Compared with the use of multiple receiving antennas, the echoes from a single receiver cannot be used directly for image reconstruction using Fourier method. The reason is revealed by using the point spread function. An additional phase is compensated for each mode before imaging process based on the array parameters and the elevation of the targets. A proof-of-concept imaging system based on a circular phased array is created, and imaging experiments of corner-reflector targets are performed in an anechoic chamber. The azimuthal image is reconstructed by the use of Fourier transform and spectral estimation methods. The azimuth resolution of the two methods is analyzed and compared through experimental data. The experimental results verify the principle of azimuth resolution and the proposed phase compensation method.

  20. A supportive architecture for CFD-based design optimisation

    NASA Astrophysics Data System (ADS)

    Li, Ni; Su, Zeya; Bi, Zhuming; Tian, Chao; Ren, Zhiming; Gong, Guanghong

    2014-03-01

    Multi-disciplinary design optimisation (MDO) is one of critical methodologies to the implementation of enterprise systems (ES). MDO requiring the analysis of fluid dynamics raises a special challenge due to its extremely intensive computation. The rapid development of computational fluid dynamic (CFD) technique has caused a rise of its applications in various fields. Especially for the exterior designs of vehicles, CFD has become one of the three main design tools comparable to analytical approaches and wind tunnel experiments. CFD-based design optimisation is an effective way to achieve the desired performance under the given constraints. However, due to the complexity of CFD, integrating with CFD analysis in an intelligent optimisation algorithm is not straightforward. It is a challenge to solve a CFD-based design problem, which is usually with high dimensions, and multiple objectives and constraints. It is desirable to have an integrated architecture for CFD-based design optimisation. However, our review on existing works has found that very few researchers have studied on the assistive tools to facilitate CFD-based design optimisation. In the paper, a multi-layer architecture and a general procedure are proposed to integrate different CFD toolsets with intelligent optimisation algorithms, parallel computing technique and other techniques for efficient computation. In the proposed architecture, the integration is performed either at the code level or data level to fully utilise the capabilities of different assistive tools. Two intelligent algorithms are developed and embedded with parallel computing. These algorithms, together with the supportive architecture, lay a solid foundation for various applications of CFD-based design optimisation. To illustrate the effectiveness of the proposed architecture and algorithms, the case studies on aerodynamic shape design of a hypersonic cruising vehicle are provided, and the result has shown that the proposed architecture

  1. The Specification of a Data Base Machine Architecture Development Facility and a Methodology for Developing Special Purpose Function Architectures,

    DTIC Science & Technology

    1980-07-01

    LIUZ ZII UNCLASSIF71ED RAUC -TR-80-26 N RADC-TR40-256 In-Moure Report July 1980 THE SPECIFICATION OF A DATA BASE MACHINE ARCHITECTURE DEVELOPMENT...ROME AIR DEVELOPME14T CENTER GRIFFISS AFB NY F/6 9/2 THE SPECIFICATION OF A DATA BASE MACHINE ARCHITECTURE DEVELOPME--ETC(U) r UNCLASSIFIED RAUC -TB BR

  2. On-demand frequency tunability of fluidic antenna implemented with gallium-based liquid metal alloy

    NASA Astrophysics Data System (ADS)

    Kim, Daeyoung; Doo, Seok Joo; Won, Heong Sup; Lee, Woojin; Jeon, Jinpyo; Chung, Sang Kug; Lee, Gil-Young; Oh, Semyoung; Lee, Jeong-Bong

    2017-04-01

    We investigated frequency tunability of a microfluidic-based antenna using on-demand manipulation of a gallium-based liquid metal alloy. The fluidic antenna was fabricated by polydimethylsiloxane (PDMS) and filled with the gallium-based liquid metal alloy (Galinstan®). It is composed of a digital number "7"-shaped feedline, and a square-shaped and a digital number "6"-shaped patterns, which are all implemented with the liquid metal. The gallium-based liquid metal was adhered to the channel surface due to its viscous oxide layer originating from the gallium oxide forming when it exposed to the air environment. We treated the liquid metal with hydrochloric acid solution to remove the oxide layer on the surface resulting in easy movement of the liquid metal in the channel, as the liquid metal surface has been transformed to be non-wettable. We controlled the physical length of the liquid metal slug filled in feedline with an applied air pressure, resulting in tuning the resonant frequency ranging from 2.2 GHz to 9.3 GHz. The fluidic antenna properties using the liquid metal's electrical conductivity and mobility were characterized by measuring the return loss (S11), and also simulated with CST Microwave Studio.

  3. Modeling of systems wireless data transmission based on antenna arrays in underwater acoustic channels

    NASA Astrophysics Data System (ADS)

    Fedosov, V. P.; Lomakina, A. V.; Legin, A. A.; Voronin, V. V.

    2016-05-01

    In this paper the system of wireless transmission of data based on the use an adaptive algorithm for processing spatial-time signals using antenna arrays is presented. In the transmission of data in a multipath propagation of signals have been used such technologies as a MIMO (Multiple input-Multiple output) and OFDM (Orthogonal frequency division multiplexing) to solve the problem of increasing the maximum speed of data transfer and the low probability of errors. The adaptation process is based on the formation of the directional pattern equivalent to the amplitude antenna array in the signal arrival direction with the highest capacity on one of propagation paths in the channel. The simulation results showed that the use of an adaptive algorithm on the reception side can significantly reduce the probability of bit errors, thus to increase throughput in an underwater acoustic data channel.

  4. Knowledge-based architecture for airborne mine and minefield detection

    NASA Astrophysics Data System (ADS)

    Agarwal, Sanjeev; Menon, Deepak; Swonger, C. W.

    2004-09-01

    One of the primary lessons learned from airborne mid-wave infrared (MWIR) based mine and minefield detection research and development over the last few years has been the fact that no single algorithm or static detection architecture is able to meet mine and minefield detection performance specifications. This is true not only because of the highly varied environmental and operational conditions under which an airborne sensor is expected to perform but also due to the highly data dependent nature of sensors and algorithms employed for detection. Attempts to make the algorithms themselves more robust to varying operating conditions have only been partially successful. In this paper, we present a knowledge-based architecture to tackle this challenging problem. The detailed algorithm architecture is discussed for such a mine/minefield detection system, with a description of each functional block and data interface. This dynamic and knowledge-driven architecture will provide more robust mine and minefield detection for a highly multi-modal operating environment. The acquisition of the knowledge for this system is predominantly data driven, incorporating not only the analysis of historical airborne mine and minefield imagery data collection, but also other "all source data" that may be available such as terrain information and time of day. This "all source data" is extremely important and embodies causal information that drives the detection performance. This information is not being used by current detection architectures. Data analysis for knowledge acquisition will facilitate better understanding of the factors that affect the detection performance and will provide insight into areas for improvement for both sensors and algorithms. Important aspects of this knowledge-based architecture, its motivations and the potential gains from its implementation are discussed, and some preliminary results are presented.

  5. Metamaterial-Based Patch Antennas and Adaptive Rectifying Circuits for High Power Rectenna Applications

    DTIC Science & Technology

    2005-01-01

    FUNDING NUMBERS Metamaterial-based Patch Antennas and Adaptive Rectifying Circuits for High N00014-04-1-0320 Power Rectenna Applications 6. AUTHOR(S...CODE Approved for public release; distribution unlimited. The efforts of this project considered two technological aspects of rectennas systems. One...technology that was emphasized power-adaptive rectifying circuits (PARCs). If a rectenna system is to be integrated into an autonomous vehicle system

  6. EM absorption reduction in wireless mobile antenna using printed paper-based metamaterial

    NASA Astrophysics Data System (ADS)

    Alam, Touhidul; Islam, Mohammad Tariqul; Kibria, Salehin; Cho, Mengu; Faruque, Mohammad Rashed Iqbal

    2017-01-01

    This paper presents a printed negative index metamaterial for electromagnetic (EM) absorption reduction in portable wireless antenna. The perceptible novelty exhibited in this paper is that EM absorption reduction toward the human head with paper-based metamaterial attachment. This research has been performed using human head phantom integrated in the commercially available CST Microwave Studio software package. The EM absorption has been reduced by 13.2 and 6% at 900 and 1800 MHz, respectively.

  7. Contextual cloud-based service oriented architecture for clinical workflow.

    PubMed

    Moreno-Conde, Jesús; Moreno-Conde, Alberto; Núñez-Benjumea, Francisco J; Parra-Calderón, Carlos

    2015-01-01

    Given that acceptance of systems within the healthcare domain multiple papers highlighted the importance of integrating tools with the clinical workflow. This paper analyse how clinical context management could be deployed in order to promote the adoption of cloud advanced services and within the clinical workflow. This deployment will be able to be integrated with the eHealth European Interoperability Framework promoted specifications. Throughout this paper, it is proposed a cloud-based service-oriented architecture. This architecture will implement a context management system aligned with the HL7 standard known as CCOW.

  8. REAGERE: a reaction-based architecture for integration and control

    NASA Astrophysics Data System (ADS)

    Berry, Nina M.; Kumara, Soundar R. T.

    1997-01-01

    This research is concerned with the design, development and implementation of a unique reaction-based multi-agent architecture (REAGERE) to integrate and control a manufacturing domain, by combining concepts from distributed problem solving and multi-agent systems. This architecture represents an emerging concept of reifying the parts, equipment, and software packages of the domain as individual agent entities. This research also improves on earlier top- down automated manufacturing systems, that suffered from lack of flexibility, upgradability, overhead difficulties, and performance problems when presented with the uncertainty and dynamics of modern competitive environments. The versatility of the domain is enhanced with the independent development of the agents and the object-oriented events that permit the agents to communicate through the underlying blackboard architecture BB1. This bottom-up concept permits the architecture's integration to rely on the agents' interactions and their perceptions of the current environmental problem(s). Hence the control and coordination of the architecture are adaptable to the agents' reactions to dynamic situations. REAGERE was applied to a simulated predefined automated manufacturing domain for the purpose of controlling and coordinating the internal processes of this domain.

  9. Efficient architecture for adaptive directional lifting-based wavelet transform

    NASA Astrophysics Data System (ADS)

    Yin, Zan; Zhang, Li; Shi, Guangming

    2010-07-01

    Adaptive direction lifting-based wavelet transform (ADL) has better performance than conventional lifting both in image compression and de-noising. However, no architecture has been proposed to hardware implement it because of its high computational complexity and huge internal memory requirements. In this paper, we propose a four-stage pipelined architecture for 2 Dimensional (2D) ADL with fast computation and high data throughput. The proposed architecture comprises column direction estimation, column lifting, row direction estimation and row lifting which are performed in parallel in a pipeline mode. Since the column processed data is transposed, the row processor can reuse the column processor which can decrease the design complexity. In the lifting step, predict and update are also performed in parallel. For an 8×8 image sub-block, the proposed architecture can finish the ADL forward transform within 78 clock cycles. The architecture is implemented on Xilinx Virtex5 device on which the frequency can achieve 367 MHz. The processed time is 212.5 ns, which can meet the request of real-time system.

  10. Experimental APL system based on a multi-microprocessor architecture

    SciTech Connect

    Sakellardis, U.

    1983-01-01

    After an introduction dealing with the fundamental aspects and main extensions of APL, a programming language based on array operations, the author describes an experimental language, APL 90, which can take advantage of multi-microprocessor architecture to overcome many limitations of standard APL. 5 references.

  11. Fault-tolerant computer architecture based on INMOS transputer processor

    NASA Technical Reports Server (NTRS)

    Ortiz, Jorge L.

    1987-01-01

    Redundant processing was used for several years in mission flight systems. In these systems, more than one processor performs the same task at the same time but only one processor is actually in real use. A fault-tolerance computer architecture based on the features provided by INMOS Transputers is presented. The Transputer architecture provides several communication links that allow data and command communication with other Transputers without the use of a bus. Additionally the Transputer allows the use of parallel processing to increase the system speed considerably. The processor architecture consists of three processors working in parallel keeping all the processors at the same operational level but only one processor is in real control of the process. The design allows each Transputer to perform a test to the other two Transputers and report the operating condition of the neighboring processors. A graphic display was developed to facilitate the identification of any problem by the user.

  12. Satellite antenna technology. Citations from the International Aerospace Abstracts data base

    NASA Technical Reports Server (NTRS)

    Zollars, G. F.

    1979-01-01

    This bibliography of citations to articles from the international literature concerns satellite antenna technology. Topics stressed are antenna design studies dealing with antenna radiation patterns and antenna arrays. This bibliography excludes articles cited in the published searches titled Communications Satellite Technology. The bibliography contains 213 citations.

  13. Satellite antenna technology. Citations from the International Aerospace Abstracts data base

    NASA Technical Reports Server (NTRS)

    Zollars, G. F.

    1979-01-01

    This bibliography of citations to articles from the international literature concerns satellite antenna technology. Topics stressed are antenna design studies dealing with antenna radiation patterns and antenna arrays. This bibliography excludes articles cited in the published searches titled Communications Satellite Technology. The bibliography contains 213 citations.

  14. Neural network based architectures for aerospace applications

    NASA Technical Reports Server (NTRS)

    Ricart, Richard

    1987-01-01

    A brief history of the field of neural networks research is given and some simple concepts are described. In addition, some neural network based avionics research and development programs are reviewed. The need for the United States Air Force and NASA to assume a leadership role in supporting this technology is stressed.

  15. Traffic and Driving Simulator Based on Architecture of Interactive Motion

    PubMed Central

    Paz, Alexander; Veeramisti, Naveen; Khaddar, Romesh; de la Fuente-Mella, Hanns; Modorcea, Luiza

    2015-01-01

    This study proposes an architecture for an interactive motion-based traffic simulation environment. In order to enhance modeling realism involving actual human beings, the proposed architecture integrates multiple types of simulation, including: (i) motion-based driving simulation, (ii) pedestrian simulation, (iii) motorcycling and bicycling simulation, and (iv) traffic flow simulation. The architecture has been designed to enable the simulation of the entire network; as a result, the actual driver, pedestrian, and bike rider can navigate anywhere in the system. In addition, the background traffic interacts with the actual human beings. This is accomplished by using a hybrid mesomicroscopic traffic flow simulation modeling approach. The mesoscopic traffic flow simulation model loads the results of a user equilibrium traffic assignment solution and propagates the corresponding traffic through the entire system. The microscopic traffic flow simulation model provides background traffic around the vicinities where actual human beings are navigating the system. The two traffic flow simulation models interact continuously to update system conditions based on the interactions between actual humans and the fully simulated entities. Implementation efforts are currently in progress and some preliminary tests of individual components have been conducted. The implementation of the proposed architecture faces significant challenges ranging from multiplatform and multilanguage integration to multievent communication and coordination. PMID:26491711

  16. Traffic and Driving Simulator Based on Architecture of Interactive Motion.

    PubMed

    Paz, Alexander; Veeramisti, Naveen; Khaddar, Romesh; de la Fuente-Mella, Hanns; Modorcea, Luiza

    2015-01-01

    This study proposes an architecture for an interactive motion-based traffic simulation environment. In order to enhance modeling realism involving actual human beings, the proposed architecture integrates multiple types of simulation, including: (i) motion-based driving simulation, (ii) pedestrian simulation, (iii) motorcycling and bicycling simulation, and (iv) traffic flow simulation. The architecture has been designed to enable the simulation of the entire network; as a result, the actual driver, pedestrian, and bike rider can navigate anywhere in the system. In addition, the background traffic interacts with the actual human beings. This is accomplished by using a hybrid mesomicroscopic traffic flow simulation modeling approach. The mesoscopic traffic flow simulation model loads the results of a user equilibrium traffic assignment solution and propagates the corresponding traffic through the entire system. The microscopic traffic flow simulation model provides background traffic around the vicinities where actual human beings are navigating the system. The two traffic flow simulation models interact continuously to update system conditions based on the interactions between actual humans and the fully simulated entities. Implementation efforts are currently in progress and some preliminary tests of individual components have been conducted. The implementation of the proposed architecture faces significant challenges ranging from multiplatform and multilanguage integration to multievent communication and coordination.

  17. Split-cross antenna based narrowband mid-infrared absorber for sensing applications

    NASA Astrophysics Data System (ADS)

    Yang, Ao; Yang, Kecheng; Zhou, Lun; Li, Junyu; Tan, Xiaochao; Liu, Huan; Song, Haisheng; Tang, Jiang; Liu, Feng; Yi, Fei

    2017-03-01

    We have investigated numerically a narrowband near unity mid-infrared absorber based on a periodic array of gold split cross antenna backed by a dielectric spacer and a gold backmirror. We systematically studied the spectral dependence on the antenna parameters and explored the optimized parameters for nanofabrication. The optimized structure has a linewidth of 39 nm at 3.17 μm and the peak absorption is 96.5%. This can be explained in terms of surface lattice resonance of the periodic structure. The investigated structure can be devised as a mid-infrared refractive index sensor. Due to the strong near field enhancement and spectral dependence on the surface dielectric conditions, the narrow linewidth arises from the coupled plasmonic-photonic modes in the structure and has potential applications in plasmonic biosensing.

  18. Antenna Designs for the Mars Exploration Rovers (MER) Spacecraft, Lander, and Rover

    NASA Technical Reports Server (NTRS)

    Vacchione, Joseph; Thelen, Michael; Brown, Paula; Huang, John; Kelly, Ken; Krishnan, Satish

    2001-01-01

    This presentation focuses on the design of antennas for the Mars Exploration Rovers (MER). Specific topics covered include: MER spacecraft architecture, the evolution of an antenna system, MER cruise stage antennas, antenna stacks, the heat-shield/back shell antenna, and lander and rover antennas. Additionally, the mission's science objectives are reviewed.

  19. JPL antenna technology development

    NASA Technical Reports Server (NTRS)

    Freeland, R. E.

    1981-01-01

    Plans for evaluating, designing, fabricating, transporting and deploying cost effective and STS compatible offset wrap rib antennas up to 300 meters in diameter for mobile communications, Earth resources observation, and for the orbiting VLBI are reviewed. The JPL surface measurement system, intended for large mesh deployable antenna applications will be demonstrated and validated as part of the antenna ground based demonstration program. Results of the offset wrap rib deployable antenna technology development will include: (1) high confidence structural designs for antennas up to 100 meters in diameter; (2) high confidence estimates of functional performance and fabrication cost for a wide range of antenna sizes (up to 300 meters in diameter); (3) risk assessment for fabricating the large size antennas; and (4) 55 meter diameter flight quality hardware that can be cost effectively completed toto accommodate a flight experiment and/or application.

  20. Compliance boundaries for multiple-frequency base station antennas in three directions.

    PubMed

    Thielens, Arno; Vermeeren, Günter; Kurup, Divya; Joseph, Wout; Martens, Luc

    2013-09-01

    In this article, compliance boundaries and allowed output powers are determined for the front, back, and side of multiple-frequency base station antennas, based on the root-mean-squared electric field, the whole-body averaged specific absorption rate (SAR), and the 10 g averaged SAR in both the limbs and the head and trunk. For this purpose, the basic restrictions and reference levels defined by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) for both the general public and occupational exposure are used. The antennas are designed for Global System for Mobile Communications around 900 MHz (GSM900), GSM1800, High Speed Packet Access (HSPA), and Long Term Evolution (LTE), and are operated with output powers at the individual frequencies up to 300 W. The compliance boundaries are estimated using finite-difference time-domain simulations with the Virtual Family Male and have been determined for three directions with respect to the antennas for 800, 900, 1800, and 2600 MHz. The reference levels are not always conservative when the radiating part of the antenna is small compared to the length of the body. Combined compliance distances, which ensure compliance with all reference levels and basic restrictions, have also been determined for each frequency. A method to determine a conservative estimation of compliance boundaries for multiple-frequency (cumulative) exposure is introduced. Using the errors on the estimated allowed powers, an uncertainty analysis is carried out for the compliance distances. Uncertainties on the compliance distances are found to be smaller than 122%.

  1. Electrically driven magnetic antenna based on multiferroic composites

    NASA Astrophysics Data System (ADS)

    Wang, X.-G.; Sukhov, A.; Chotorlishvili, L.; Jia, C.-L.; Guo, G.-H.; Berakdar, J.

    2017-03-01

    We suggest and demonstrate via large scale numerical simulations an electrically operated spin-wave inducer based on composite multiferroic junctions. Specifically, we consider an interfacially coupled ferromagnetic/ferroelectric structure that emits controllably spin waves in the ferromagnets if the ferroelectric polarization is poled by an external electric field. The roles of geometry and material properties are discussed.

  2. Electrically driven magnetic antenna based on multiferroic composites.

    PubMed

    Wang, X-G; Sukhov, A; Chotorlishvili, L; Jia, C-L; Guo, G-H; Berakdar, J

    2017-03-08

    We suggest and demonstrate via large scale numerical simulations an electrically operated spin-wave inducer based on composite multiferroic junctions. Specifically, we consider an interfacially coupled ferromagnetic/ferroelectric structure that emits controllably spin waves in the ferromagnets if the ferroelectric polarization is poled by an external electric field. The roles of geometry and material properties are discussed.

  3. Trust-based information system architecture for personal wellness.

    PubMed

    Ruotsalainen, Pekka; Nykänen, Pirkko; Seppälä, Antto; Blobel, Bernd

    2014-01-01

    Modern eHealth, ubiquitous health and personal wellness systems take place in an unsecure and ubiquitous information space where no predefined trust occurs. This paper presents novel information model and an architecture for trust based privacy management of personal health and wellness information in ubiquitous environment. The architecture enables a person to calculate a dynamic and context-aware trust value for each service provider, and using it to design personal privacy policies for trustworthy use of health and wellness services. For trust calculation a novel set of measurable context-aware and health information-sensitive attributes is developed. The architecture enables a person to manage his or her privacy in ubiquitous environment by formulating context-aware and service provider specific policies. Focus groups and information modelling was used for developing a wellness information model. System analysis method based on sequential steps that enable to combine results of analysis of privacy and trust concerns and the selection of trust and privacy services was used for development of the information system architecture. Its services (e.g. trust calculation, decision support, policy management and policy binding services) and developed attributes enable a person to define situation-aware policies that regulate the way his or her wellness and health information is processed.

  4. Scalable, distributed data mining using an agent based architecture

    SciTech Connect

    Kargupta, H.; Hamzaoglu, I.; Stafford, B.

    1997-05-01

    Algorithm scalability and the distributed nature of both data and computation deserve serious attention in the context of data mining. This paper presents PADMA (PArallel Data Mining Agents), a parallel agent based system, that makes an effort to address these issues. PADMA contains modules for (1) parallel data accessing operations, (2) parallel hierarchical clustering, and (3) web-based data visualization. This paper describes the general architecture of PADMA and experimental results.

  5. The architecture of evidence-based gynaecology.

    PubMed

    Khan, Khalid S

    2006-10-01

    Modern evidence-based medicine (EBM) and its predecessor 'Medecin d'Observation' both emphasise that potential advances in healthcare must be researched and proven to do more good than harm using the principles of clinical epidemiology before they are incorporated into medical practice. EBM is considered an important advance in improving clinical care in gynaecology but EBM skills have traditionally not been covered in undergraduate or postgraduate education. Therefore there is a perceived need to compile texts on various aspects of gynaecological practice using EBM principles. This is what these two issues of the Best Practice series hope to achieve. The various chapters will provide readers with clinical advice generated from critically appraised information that has been identified as addressing relevant questions.

  6. GMI High Frequency Antenna Pattern Correction Update Based on GPM Inertial Hold and Comparison with ATMS

    NASA Technical Reports Server (NTRS)

    Draper, David W.

    2015-01-01

    In an inertial hold, the spacecraft does not attempt to maintain geodetic pointing, but rather maintains the same inertial position throughout the orbit. The result is that the spacecraft appears to pitch from 0 to 360 degrees around the orbit. Two inertial holds were performed with the GPM spacecraft: 1) May 20, 2014 16:48:31 UTC-18:21:04 UTC, spacecraft flying forward +X (0yaw), pitch from 55 degrees (FCS) to 415 degrees (FCS) over the orbit2) Dec 9, 2014 01:30:00 UTC-03:02:32 UTC, spacecraft flying backward X (180yaw), pitch from 0 degrees (FCS) to 360 degrees (FCS) over the orbitThe inertial hold affords a view of the earth through the antenna backlobe. The antenna spillover correction may be evaluated based on the inertial hold data.The current antenna pattern correction does not correct for spillover in the 166 and 183 GHz channels. The two inertial holds both demonstrate that there is significant spillover from the 166 and 183 GHz channels. By not correcting the spillover, the 166 and 183 GHz channels are biased low by about 1.8 to 3K. We propose to update the GMI calibration algorithm with the spill-over correction presented in this document for 166 GHz and 183 GHz.

  7. Beam reconfigurable antenna for the THz band based on a graphene high impedance surface

    NASA Astrophysics Data System (ADS)

    Radwan, Ahmed; Verri, Valentina; D'Amico, Michele; Gentili, G. Guido

    2017-01-01

    In this paper a reconfigurable beam antenna is proposed for THz applications, based on a switchable Graphene High Impedance Surface (G-HIS) that acts as a reflector for a primary radiator. The Graphene-HIS structure composed of two layers of graphene cells arranged in a 5×5 array, the two planes of the array are separated by a thin silicon oxide layer; patches in the same row are connected together, to be biased by a common DC voltage to the entire row; this gives the ability to control the graphene conductivity σ. The results show that the shape of the radiation pattern can be changed by changing the voltage applied to each row of G-HIS array. The antenna was fabricated and characterized using a THz-TDS laser system. Measurements are in good agreement with simulations as far as the graphene surface impedance and the resonance frequency are concerned. The scanning reflection on the antenna surface due to the change on the applied voltage is presented to show the effect of biased graphene layer on the dipole properties.

  8. Spoof surface plasmon based planar antennas for the realization of Terahertz hotspots.

    PubMed

    Zhang, Yusheng; Han, Zhanghua

    2015-12-22

    Novel spoof surface plasmon based terahertz (THz) antennas are realized using a few number of rectangular grooves perforated in ultrathin metal stripes and the properties of them, including both scattering cross sections and field enhancement, are numerically analyzed. The dependence of these properties on the incident angle and groove number is discussed and the results show that sharp resonances in scattering cross section spectra associated with strong local field enhancement can be achieved. These resonances are due to the formation of Fabry-Perot resonances of the spoof surface plasmon mode and it is found that the order of resonance exhibiting strongest field enhancements is found to coincide with the number of grooves at normal incidence, due to hybridization of the antenna resonance with the individual groove resonance. The terahertz hotspots within the grooves at resonances due to the local field enhancement may open up new possibilities for the investigation of terahertz-matter interactions and boost a variety of THz applications including novel sensing and THz detections. The planar stripe antennas with sharper resonances than dipolar-like resonances, together with their ease of fabrication may also promise new design methodology for metamaterials.

  9. Spoof surface plasmon based planar antennas for the realization of Terahertz hotspots

    PubMed Central

    Zhang, Yusheng; Han, Zhanghua

    2015-01-01

    Novel spoof surface plasmon based terahertz (THz) antennas are realized using a few number of rectangular grooves perforated in ultrathin metal stripes and the properties of them, including both scattering cross sections and field enhancement, are numerically analyzed. The dependence of these properties on the incident angle and groove number is discussed and the results show that sharp resonances in scattering cross section spectra associated with strong local field enhancement can be achieved. These resonances are due to the formation of Fabry-Perot resonances of the spoof surface plasmon mode and it is found that the order of resonance exhibiting strongest field enhancements is found to coincide with the number of grooves at normal incidence, due to hybridization of the antenna resonance with the individual groove resonance. The terahertz hotspots within the grooves at resonances due to the local field enhancement may open up new possibilities for the investigation of terahertz-matter interactions and boost a variety of THz applications including novel sensing and THz detections. The planar stripe antennas with sharper resonances than dipolar-like resonances, together with their ease of fabrication may also promise new design methodology for metamaterials. PMID:26691003

  10. Data/knowledge Base Processing Using Optical Associative Architectures

    NASA Astrophysics Data System (ADS)

    Akyokus, Selim

    Optical storage, communication, and processing technologies will have a great impact on the future data/knowledge base processing systems. The use of optics in data/knowledge base processing requires new design methods, architectures, and algorithms to apply the optical technology successfully. In this dissertation, three optical associative architectures are proposed. The basic data element in the proposed systems is a 2-D data page. Pages of database relations are stored in a page-oriented optical mass memory, retrieved, and processed in parallel. The first architecture uses a 1-D optical content addressable memory (OCAM) as the main functional unit. A 1-D OCAM is basically an optical vector-matrix multiplier which works as a CAM due to the spatial coding used for bit matching and masking. A 1-D OCAM can compare a search argument with a data page in parallel. The second architecture uses a 2-D OCAM as a main functional unit. A 2-D OCAM is an optical matrix-matrix multiplier which enables the comparison of a page of search arguments with a data page in parallel and in a single step. This architecture allows the execution of multiple selection and join operations very fast. The third architecture uses an optical perfect shuffle network for data routing and a processing array for performing parallel logic operations. A processing array based on symbolic substitution logic is introduced, and the use of a smart SLM as processing array is discussed. The symbolic substitution rules and algorithms for the implementation of search and bitonic sort operations are given for the proposed system. The implementation of relational database operations: selection, projection, update, deletion, sorting, duplication removal, aggregation functions, join, and set operations are described for the proposed systems, timing equations are developed for each operation, and their performances are analyzed. The proposed architectures take advantage of one-to-one mapping among the physical

  11. Trust Information-Based Privacy Architecture for Ubiquitous Health

    PubMed Central

    2013-01-01

    Background Ubiquitous health is defined as a dynamic network of interconnected systems that offers health services independent of time and location to a data subject (DS). The network takes place in open and unsecure information space. It is created and managed by the DS who sets rules that regulate the way personal health information is collected and used. Compared to health care, it is impossible in ubiquitous health to assume the existence of a priori trust between the DS and service providers and to produce privacy using static security services. In ubiquitous health features, business goals and regulations systems followed often remain unknown. Furthermore, health care-specific regulations do not rule the ways health data is processed and shared. To be successful, ubiquitous health requires novel privacy architecture. Objective The goal of this study was to develop a privacy management architecture that helps the DS to create and dynamically manage the network and to maintain information privacy. The architecture should enable the DS to dynamically define service and system-specific rules that regulate the way subject data is processed. The architecture should provide to the DS reliable trust information about systems and assist in the formulation of privacy policies. Furthermore, the architecture should give feedback upon how systems follow the policies of DS and offer protection against privacy and trust threats existing in ubiquitous environments. Methods A sequential method that combines methodologies used in system theory, systems engineering, requirement analysis, and system design was used in the study. In the first phase, principles, trust and privacy models, and viewpoints were selected. Thereafter, functional requirements and services were developed on the basis of a careful analysis of existing research published in journals and conference proceedings. Based on principles, models, and requirements, architectural components and their interconnections

  12. Model-based service-oriented architectures for Internetworked Enterprises

    NASA Astrophysics Data System (ADS)

    Bianchini, Devis; Brambilla, Marco; Campi, Alessandro; Cappiello, Cinzia; Ceri, Stefano; Comuzzi, Marco; de Antonellis, Valeria; Pernici, Barbara; Plebani, Pierluigi

    Service-oriented architectures (SOA) provide the basis to (re)design business processes in order to develop flexible applications where available services are dynamically composed to satisfy business goals. The adoption of this type of architecture enables the design of information systems that connect IEs to each other to run collaborative business processes. In fact, organizations can design service-based processes based either on simple internal applications or on external services. This chapter provides models and methods for the design and execution of service-based processes able to exploit all the services offered in an IEs registry. This service registry contains services that need to be defined with the same granularity and described via the same functional and non-functional models. The alignment in process and service design and modeling is discussed in this chapter, to enable the adoption of efficient techniques for service sharing, discovery and invocation.

  13. Aircraft antennas/conformal antennas missile antennas

    NASA Astrophysics Data System (ADS)

    Solbach, Klaus

    1987-04-01

    Three major areas of airborne microwave antennas are examined. The basic system environment for missile telemetry/telecommand and fuze functions is sketched and the basic antenna design together with practical examples are discussed. The principle requirements of modern nose radar flat plate antennas are shown to result from missile/aircraft system requirements. Basic principles of slotted waveguide antenna arrays are sketched and practical antenna designs are discussed. The present early warning system designs are sketched to point out requirements and performance of practical radar warning and jamming antennas (broadband spiral antennas and horn radiators). With respect to newer developments in the ECM scenario, some demonstrated and proposed antenna systems (lens fed arrays, phased array, active array) are discussed.

  14. Innovative fiber-laser architecture-based compact wind lidar

    NASA Astrophysics Data System (ADS)

    Prasad, Narasimha S.; Tracy, Allen; Vetorino, Steve; Higgins, Richard; Sibell, Russ

    2016-03-01

    This paper describes an innovative, compact and eyesafe coherent lidar system developed for use in wind and wake vortex sensing applications. This advanced lidar system is field ruggedized with reduced size, weight, and power consumption (SWaP) configured based on an all-fiber and modular architecture. The all-fiber architecture is developed using a fiber seed laser that is coupled to uniquely configured fiber amplifier modules and associated photonic elements including an integrated 3D scanner. The scanner provides user programmable continuous 360 degree azimuth and 180 degree elevation scan angles. The system architecture eliminates free-space beam alignment issues and allows plug and play operation using graphical user interface software modules. Besides its all fiber architecture, the lidar system also provides pulsewidth agility to aid in improving range resolution. Operating at 1.54 microns and with a PRF of up to 20 KHz, the wind lidar is air cooled with overall dimensions of 30" x 46" x 60" and is designed as a Class 1 system. This lidar is capable of measuring wind velocities greater than 120 +/- 0.2 m/s over ranges greater than 10 km and with a range resolution of less than 15 m. This compact and modular system is anticipated to provide mobility, reliability, and ease of field deployment for wind and wake vortex measurements. The current lidar architecture is amenable for trace gas sensing and as such it is being evolved for airborne and space based platforms. In this paper, the key features of wind lidar instrumentation and its functionality are discussed followed by results of recent wind forecast measurements on a wind farm.

  15. Antenna Controller Replacement Software

    NASA Technical Reports Server (NTRS)

    Chao, Roger Y.; Morgan, Scott C.; Strain, Martha M.; Rockwell, Stephen T.; Shimizu, Kenneth J.; Tehrani, Barzia J.; Kwok, Jaclyn H.; Tuazon-Wong, Michelle; Valtier, Henry; Nalbandi, Reza; Wert, Michael; Leung, Patrick

    2010-01-01

    The Antenna Controller Replacement (ACR) software accurately points and monitors the Deep Space Network (DSN) 70-m and 34-m high-efficiency (HEF) ground-based antennas that are used to track primarily spacecraft and, periodically, celestial targets. To track a spacecraft, or other targets, the antenna must be accurately pointed at the spacecraft, which can be very far away with very weak signals. ACR s conical scanning capability collects the signal in a circular pattern around the target, calculates the location of the strongest signal, and adjusts the antenna pointing to point directly at the spacecraft. A real-time, closed-loop servo control algorithm performed every 0.02 second allows accurate positioning of the antenna in order to track these distant spacecraft. Additionally, this advanced servo control algorithm provides better antenna pointing performance in windy conditions. The ACR software provides high-level commands that provide a very easy user interface for the DSN operator. The operator only needs to enter two commands to start the antenna and subreflector, and Master Equatorial tracking. The most accurate antenna pointing is accomplished by aligning the antenna to the Master Equatorial, which because of its small size and sheltered location, has the most stable pointing. The antenna has hundreds of digital and analog monitor points. The ACR software provides compact displays to summarize the status of the antenna, subreflector, and the Master Equatorial. The ACR software has two major functions. First, it performs all of the steps required to accurately point the antenna (and subreflector and Master Equatorial) at the spacecraft (or celestial target). This involves controlling the antenna/ subreflector/Master-Equatorial hardware, initiating and monitoring the correct sequence of operations, calculating the position of the spacecraft relative to the antenna, executing the real-time servo control algorithm to maintain the correct position, and

  16. A Hybrid Power Management (HPM) Based Vehicle Architecture

    NASA Technical Reports Server (NTRS)

    Eichenberg, Dennis J.

    2011-01-01

    Society desires vehicles with reduced fuel consumption and reduced emissions. This presents a challenge and an opportunity for industry and the government. The NASA John H. Glenn Research Center (GRC) has developed a Hybrid Power Management (HPM) based vehicle architecture for space and terrestrial vehicles. GRC's Electrical and Electromagnetics Branch of the Avionics and Electrical Systems Division initiated the HPM Program for the GRC Technology Transfer and Partnership Office. HPM is the innovative integration of diverse, state-of-the-art power devices in an optimal configuration for space and terrestrial applications. The appropriate application and control of the various power devices significantly improves overall system performance and efficiency. The basic vehicle architecture consists of a primary power source, and possibly other power sources, providing all power to a common energy storage system, which is used to power the drive motors and vehicle accessory systems, as well as provide power as an emergency power system. Each component is independent, permitting it to be optimized for its intended purpose. This flexible vehicle architecture can be applied to all vehicles to considerably improve system efficiency, reliability, safety, security, and performance. This unique vehicle architecture has the potential to alleviate global energy concerns, improve the environment, stimulate the economy, and enable new missions.

  17. An isolation-enhanced quad-element antenna using suspended solid wires for LTE small-cell base stations

    NASA Astrophysics Data System (ADS)

    Chen, Yen-Sheng; Zhou, Huang-Cheng

    2017-05-01

    This paper presents a multiple-input-multiple-output (MIMO) antenna that has four-unit elements enabled by an isolation technique for long-term evolution (LTE) small-cell base stations. While earlier studies on MIMO base-station antennas cope with either a lower LTE band (698-960 MHz) or an upper LTE band (1710-2690 MHz), the proposed antenna meets the full LTE specification, yet it uses the maximum number of unit elements to increase channel capacity. The antenna configuration is optimized for good impedance matching and high radiation efficiency. In particular, as the spacing between unit elements is so small that severe mutual coupling occurs, we propose a simple structure with extremely low costs to enhance the isolation. By using suspended solid wires interconnecting the position having strong coupled current of two adjacent elements, an isolation enhancement of 37 dB is achieved. Although solid wires inherently aim at direct-current applications, this work successfully employs such a low-cost technique to microwave antenna development. Experimental results have validated the design guidelines and the proposed configuration, showing that antenna performances including impedance matching, isolation, radiation features, signal correlation, and channel capacity gain are highly desired for LTE small-cell base stations.

  18. Mitigating illumination gradients in a SAR image based on the image data and antenna beam pattern

    SciTech Connect

    Doerry, Armin W.

    2013-04-30

    Illumination gradients in a synthetic aperture radar (SAR) image of a target can be mitigated by determining a correction for pixel values associated with the SAR image. This correction is determined based on information indicative of a beam pattern used by a SAR antenna apparatus to illuminate the target, and also based on the pixel values associated with the SAR image. The correction is applied to the pixel values associated with the SAR image to produce corrected pixel values that define a corrected SAR image.

  19. Attitude and vibration control of a large flexible space-based antenna

    NASA Technical Reports Server (NTRS)

    Joshi, S. M.

    1982-01-01

    Control systems synthesis is considered for controlling the rigid body attitude and elastic motion of a large deployable space-based antenna. Two methods for control systems synthesis are considered. The first method utilizes the stability and robustness properties of the controller consisting of torque actuators and collocated attitude and rate sensors. The second method is based on the linear-quadratic-Gaussian control theory. A combination of the two methods, which results in a two level hierarchical control system, is also briefly discussed. The performance of the controllers is analyzed by computing the variances of pointing errors, feed misalignment errors and surface contour errors in the presence of sensor and actuator noise.

  20. Architectural approaches for HL7-based health information systems implementation.

    PubMed

    López, D M; Blobel, B

    2010-01-01

    Information systems integration is hard, especially when semantic and business process interoperability requirements need to be met. To succeed, a unified methodology, approaching different aspects of systems architecture such as business, information, computational, engineering and technology viewpoints, has to be considered. The paper contributes with an analysis and demonstration on how the HL7 standard set can support health information systems integration. Based on the Health Information Systems Development Framework (HIS-DF), common architectural models for HIS integration are analyzed. The framework is a standard-based, consistent, comprehensive, customizable, scalable methodology that supports the design of semantically interoperable health information systems and components. Three main architectural models for system integration are analyzed: the point to point interface, the messages server and the mediator models. Point to point interface and messages server models are completely supported by traditional HL7 version 2 and version 3 messaging. The HL7 v3 standard specification, combined with service-oriented, model-driven approaches provided by HIS-DF, makes the mediator model possible. The different integration scenarios are illustrated by describing a proof-of-concept implementation of an integrated public health surveillance system based on Enterprise Java Beans technology. Selecting the appropriate integration architecture is a fundamental issue of any software development project. HIS-DF provides a unique methodological approach guiding the development of healthcare integration projects. The mediator model - offered by the HIS-DF and supported in HL7 v3 artifacts - is the more promising one promoting the development of open, reusable, flexible, semantically interoperable, platform-independent, service-oriented and standard-based health information systems.

  1. Autonomous, Decentralized Grid Architecture: Prosumer-Based Distributed Autonomous Cyber-Physical Architecture for Ultra-Reliable Green Electricity Networks

    SciTech Connect

    2012-01-11

    GENI Project: Georgia Tech is developing a decentralized, autonomous, internet-like control architecture and control software system for the electric power grid. Georgia Tech’s new architecture is based on the emerging concept of electricity prosumers—economically motivated actors that can produce, consume, or store electricity. Under Georgia Tech’s architecture, all of the actors in an energy system are empowered to offer associated energy services based on their capabilities. The actors achieve their sustainability, efficiency, reliability, and economic objectives, while contributing to system-wide reliability and efficiency goals. This is in marked contrast to the current one-way, centralized control paradigm.

  2. Dual-band periodic beam scanning antenna using eighth mode substrate integrated waveguide based metamaterial transmission line

    NASA Astrophysics Data System (ADS)

    Wu, Guo-cheng; Wang, Guang-ming; Liang, Jian-gang; Gao, Xiang-jun

    2017-05-01

    In this paper, a novel dual-band periodic metamaterial antenna with a continuous beam scanning property from backward to forward directions is first proposed by using an eighth mode substrate integrated waveguide (EMSIW) based metamaterial transmission line (MTM TL). The proposed beam scanning antenna consists of 11 unit cells of the EMSIW based MTM TL, and the unit cell of MTM TL is designed by etching two different interdigital fingers on the upper ground of EMSIW. The MTM TL has two balanced composite right/left-handed (CRLH) passbands, and exhibits a continuous phase constant changing from negative to positive values within the two passbands. For verification, the proposed dual-band periodic beam scanning antenna is fabricated and measured. The measured results show that the fabricated beam scanning antenna has two operating frequency bands of 4.2-6.2 GHz (38.5%) and 10.2-11.1 GHz (8.5%), with a return loss better than 10 dB, and achieving a continuous beam scanning property from backward  -62° to forward  +55°and backward  -27° to forward  +18° within the two operating frequency bands, respectively. The measured peak antenna gain is 14.7 and 11.7 dB in the first and second operating frequency band. Moreover, the proposed antenna has a filtering capability in the two operating frequency bands. Besides, the measured and simulated results of the proposed dual-band periodic antenna are in good agreement with each other, indicating that the significance and effectiveness of this method to design beam scanning antenna.

  3. Cluster-based architecture for fault-tolerant quantum computation

    SciTech Connect

    Fujii, Keisuke; Yamamoto, Katsuji

    2010-04-15

    We present a detailed description of an architecture for fault-tolerant quantum computation, which is based on the cluster model of encoded qubits. In this cluster-based architecture, concatenated computation is implemented in a quite different way from the usual circuit-based architecture where physical gates are recursively replaced by logical gates with error-correction gadgets. Instead, some relevant cluster states, say fundamental clusters, are recursively constructed through verification and postselection in advance for the higher-level one-way computation, which namely provides error-precorrection of gate operations. A suitable code such as the Steane seven-qubit code is adopted for transversal operations. This concatenated construction of verified fundamental clusters has a simple transversal structure of logical errors, and achieves a high noise threshold {approx}3% for computation by using appropriate verification procedures. Since the postselection is localized within each fundamental cluster with the help of deterministic bare controlled-Z gates without verification, divergence of resources is restrained, which reconciles postselection with scalability.

  4. Cluster-based architecture for fault-tolerant quantum computation

    NASA Astrophysics Data System (ADS)

    Fujii, Keisuke; Yamamoto, Katsuji

    2010-04-01

    We present a detailed description of an architecture for fault-tolerant quantum computation, which is based on the cluster model of encoded qubits. In this cluster-based architecture, concatenated computation is implemented in a quite different way from the usual circuit-based architecture where physical gates are recursively replaced by logical gates with error-correction gadgets. Instead, some relevant cluster states, say fundamental clusters, are recursively constructed through verification and postselection in advance for the higher-level one-way computation, which namely provides error-precorrection of gate operations. A suitable code such as the Steane seven-qubit code is adopted for transversal operations. This concatenated construction of verified fundamental clusters has a simple transversal structure of logical errors, and achieves a high noise threshold ~3% for computation by using appropriate verification procedures. Since the postselection is localized within each fundamental cluster with the help of deterministic bare controlled-Z gates without verification, divergence of resources is restrained, which reconciles postselection with scalability.

  5. Packet Forwarding Scheme Based on Interworking Architecture for Future Internet

    NASA Astrophysics Data System (ADS)

    Kim, Seokhoon; Ryoo, Intae

    This paper introduces a packet forwarding scheme based on interworking architecture that can provide quite a good QoS by minimizing processing delay which is the major part of the timeliness factor in New Generation IP-based networks. Based on path and resource reservation mechanism, the POSIA makes routers on the packet forwarding path synchronize with each other and then forward packets. We have shown that the POSIA outperforms the existing packet forwarding schemes like IntServ, DiffServ and MPLS through computer simulations using OPNET.

  6. Biologically-inspired, electrically small antenna arrays

    NASA Astrophysics Data System (ADS)

    Masoumi, Amir Reza

    First, the motivation behind adding a passive external coupling network after antenna arrays is discussed, the concept of biomimetic antenna arrays (BMAAs) introduced and some of the previous work done in this area have been reviewed. Next, a BMAA which achieves an angular resolution of roughly 15 times its regular counterpart is introduced and fully characterized. The introduced BMAA employs transformers which considerably degrade its performance, namely its output power. To cicumvent this shortcoming a new architecture of a BMAA that does not employ transformers and therefore yields a higher output power for the same angular resolution has been subsequently presented. Moreover, a detailed noise analysis of this BMAA is carried out and the output noise of the new architecture is compared with the output noise of the original design. The modified twoelement BMAA architecture is then extended to multiple elements. A novel nonlinear optimization process is introduced that maximizes the total power captured by the BMAA for a given angular resolution and the concept illustrated for a three-element antenna array. Next an optimum two-element BMAA which achieves the maximum possible angular resolution while obtaining the same output power level of a regular antenna array with the same elements and spacing is introduced. A novel two-element superdirective array based on this optimum BMAA has been also discussed. The passive BMAAs discussed in this thesis have a relatively narrow bandwidth. To extend the bandwidth of BMAAs, non- Foster networks have been employed in their external coupling networks and it has been demonstrated that they can increase their bandwidth by a factor of roughly 33. Finally, the BMAA concept has been extended to nano-antenna arrays and a concept for designing sub-wavelength angle-sensing detectors at optical wavelengths has been introduced.

  7. Troposcatter antenna positioner

    NASA Astrophysics Data System (ADS)

    Birkemeier, W. P.; Fontaine, A. B.

    1980-08-01

    This report covers results of a contract to provide for a rapid and accurate alignment procedure of troposcatter antennas. An experimental model embodying a microprocessor based computation routine at the receive antenna and a stable transmitted frequency allows for alignment of antennas along the great circle path. The test data show that an alignment accuracy of better than plus or minus 1/3 degree or approximately plus or minus 1/10 of a beamwidth could be accomplished in approximately 10 minutes.

  8. An Object-Based Architecture for Biomedical Expert Database Systems

    PubMed Central

    Barsalou, Thierry

    1988-01-01

    Objects play a major role in both database and artificial intelligence research. In this paper, we present a novel architecture for expert database systems that introduces an object-based interface between relational databases and expert systems. We exploit a semantic model of the database structure to map relations automatically into object templates, where each template can be a complex combination of join and projection operations. Moreover, we arrange the templates into object networks that represent different views of the same database. Separate processes instantiate those templates using data from the base relations, cache the resulting instances in main memory, navigate through a given network's objects, and update the database according to changes made at the object layer. In the context of an immunologic-research application, we demonstrate the capabilities of a prototype implementation of the architecture. The resulting model provides enhanced tools for database structuring and manipulation. In addition, this architecture supports efficient bidirectional communication between database and expert systems through the shared object layer.

  9. Do Performance-Based Codes Support Universal Design in Architecture?

    PubMed

    Grangaard, Sidse; Frandsen, Anne Kathrine

    2016-01-01

    The research project 'An analysis of the accessibility requirements' studies how Danish architectural firms experience the accessibility requirements of the Danish Building Regulations and it examines their opinions on how future regulative models can support innovative and inclusive design - Universal Design (UD). The empirical material consists of input from six workshops to which all 700 Danish Architectural firms were invited, as well as eight group interviews. The analysis shows that the current prescriptive requirements are criticized for being too homogenous and possibilities for differentiation and zoning are required. Therefore, a majority of professionals are interested in a performance-based model because they think that such a model will support 'accessibility zoning', achieving flexibility because of different levels of accessibility in a building due to its performance. The common understanding of accessibility and UD is directly related to buildings like hospitals and care centers. When the objective is both innovative and inclusive architecture, the request of a performance-based model should be followed up by a knowledge enhancement effort in the building sector. Bloom's taxonomy of educational objectives is suggested as a tool for such a boost. The research project has been financed by the Danish Transport and Construction Agency.

  10. SIFT - A Component-Based Integration Architecture for Enterprise Analytics

    SciTech Connect

    Thurman, David A.; Almquist, Justin P.; Gorton, Ian; Wynne, Adam S.; Chatterton, Jack

    2007-02-01

    Architectures and technologies for enterprise application integration are relatively mature, resulting in a range of standards-based and proprietary middleware technologies. In the domain of complex analytical applications, integration architectures are not so well understood. Analytical applications such as those used in scientific discovery, emergency response, financial and intelligence analysis exert unique demands on their underlying architecture. These demands make existing integration middleware inappropriate for use in enterprise analytics environments. In this paper we describe SIFT (Scalable Information Fusion and Triage), a platform designed for integrating the various components that comprise enterprise analytics applications. SIFT exploits a common pattern for composing analytical components, and extends an existing messaging platform with dynamic configuration mechanisms and scaling capabilities. We demonstrate the use of SIFT to create a decision support platform for quality control based on large volumes of incoming delivery data. The strengths of the SIFT solution are discussed, and we conclude by describing where further work is required to create a complete solution applicable to a wide range of analytical application domains.

  11. The AI Bus architecture for distributed knowledge-based systems

    NASA Technical Reports Server (NTRS)

    Schultz, Roger D.; Stobie, Iain

    1991-01-01

    The AI Bus architecture is layered, distributed object oriented framework developed to support the requirements of advanced technology programs for an order of magnitude improvement in software costs. The consequent need for highly autonomous computer systems, adaptable to new technology advances over a long lifespan, led to the design of an open architecture and toolbox for building large scale, robust, production quality systems. The AI Bus accommodates a mix of knowledge based and conventional components, running on heterogeneous, distributed real world and testbed environment. The concepts and design is described of the AI Bus architecture and its current implementation status as a Unix C++ library or reusable objects. Each high level semiautonomous agent process consists of a number of knowledge sources together with interagent communication mechanisms based on shared blackboards and message passing acquaintances. Standard interfaces and protocols are followed for combining and validating subsystems. Dynamic probes or demons provide an event driven means for providing active objects with shared access to resources, and each other, while not violating their security.

  12. Space-Based Information Infrastructure Architecture for Broadband Services

    NASA Technical Reports Server (NTRS)

    Price, Kent M.; Inukai, Tom; Razdan, Rajendev; Lazeav, Yvonne M.

    1996-01-01

    This study addressed four tasks: (1) identify satellite-addressable information infrastructure markets; (2) perform network analysis for space-based information infrastructure; (3) develop conceptual architectures; and (4) economic assessment of architectures. The report concludes that satellites will have a major role in the national and global information infrastructure, requiring seamless integration between terrestrial and satellite networks. The proposed LEO, MEO, and GEO satellite systems have satellite characteristics that vary widely. They include delay, delay variations, poorer link quality and beam/satellite handover. The barriers against seamless interoperability between satellite and terrestrial networks are discussed. These barriers are the lack of compatible parameters, standards and protocols, which are presently being evaluated and reduced.

  13. GEARS: An Enterprise Architecture Based On Common Ground Services

    NASA Astrophysics Data System (ADS)

    Petersen, S.

    2014-12-01

    Earth observation satellites collect a broad variety of data used in applications that range from weather forecasting to climate monitoring. Within NOAA the National Environmental Satellite Data and Information Service (NESDIS) supports these applications by operating satellites in both geosynchronous and polar orbits. Traditionally NESDIS has acquired and operated its satellites as stand-alone systems with their own command and control, mission management, processing, and distribution systems. As the volume, velocity, veracity, and variety of sensor data and products produced by these systems continues to increase, NESDIS is migrating to a new concept of operation in which it will operate and sustain the ground infrastructure as an integrated Enterprise. Based on a series of common ground services, the Ground Enterprise Architecture System (GEARS) approach promises greater agility, flexibility, and efficiency at reduced cost. This talk describes the new architecture and associated development activities, and presents the results of initial efforts to improve product processing and distribution.

  14. A safety-based decision making architecture for autonomous systems

    NASA Technical Reports Server (NTRS)

    Musto, Joseph C.; Lauderbaugh, L. K.

    1991-01-01

    Engineering systems designed specifically for space applications often exhibit a high level of autonomy in the control and decision-making architecture. As the level of autonomy increases, more emphasis must be placed on assimilating the safety functions normally executed at the hardware level or by human supervisors into the control architecture of the system. The development of a decision-making structure which utilizes information on system safety is detailed. A quantitative measure of system safety, called the safety self-information, is defined. This measure is analogous to the reliability self-information defined by McInroy and Saridis, but includes weighting of task constraints to provide a measure of both reliability and cost. An example is presented in which the safety self-information is used as a decision criterion in a mobile robot controller. The safety self-information is shown to be consistent with the entropy-based Theory of Intelligent Machines defined by Saridis.

  15. A Coupled Simulation Architecture for Agent-Based/Geohydrological Modelling

    NASA Astrophysics Data System (ADS)

    Jaxa-Rozen, M.

    2016-12-01

    The quantitative modelling of social-ecological systems can provide useful insights into the interplay between social and environmental processes, and their impact on emergent system dynamics. However, such models should acknowledge the complexity and uncertainty of both of the underlying subsystems. For instance, the agent-based models which are increasingly popular for groundwater management studies can be made more useful by directly accounting for the hydrological processes which drive environmental outcomes. Conversely, conventional environmental models can benefit from an agent-based depiction of the feedbacks and heuristics which influence the decisions of groundwater users. From this perspective, this work describes a Python-based software architecture which couples the popular NetLogo agent-based platform with the MODFLOW/SEAWAT geohydrological modelling environment. This approach enables users to implement agent-based models in NetLogo's user-friendly platform, while benefiting from the full capabilities of MODFLOW/SEAWAT packages or reusing existing geohydrological models. The software architecture is based on the pyNetLogo connector, which provides an interface between the NetLogo agent-based modelling software and the Python programming language. This functionality is then extended and combined with Python's object-oriented features, to design a simulation architecture which couples NetLogo with MODFLOW/SEAWAT through the FloPy library (Bakker et al., 2016). The Python programming language also provides access to a range of external packages which can be used for testing and analysing the coupled models, which is illustrated for an application of Aquifer Thermal Energy Storage (ATES).

  16. A True Metasurface Antenna

    PubMed Central

    Badawe, Mohamed El; Almoneef, Thamer S.; Ramahi, Omar M.

    2016-01-01

    We present a true metasurface antenna based on electrically-small resonators. The resonators are placed on a flat surface and connected to one feed point using corporate feed. Unlike conventional array antennas where the distance between adjacent antennas is half wavelength to reduce mutual coupling between adjacent antennas, here the distance between the radiating elements is electrically very small to affect good impedance matching of each resonator to its feed. A metasurface antenna measuring 1.2λ × 1.2λ and designed to operate at 3 GHz achieved a gain of 12 dBi. A prototype was fabricated and tested showing good agreement between numerical simulations and experimental results. Through numerical simulation, we show that the metasurface antenna has the ability to provide beam steering by phasing all the resonators appropriately. PMID:26759177

  17. Emission characteristics of photoconductive antennas based on low-temperature-grown GaAs and semi-insulating GaAs.

    PubMed

    Tani, M; Matsuura, S; Sakai, K; Nakashima, S

    1997-10-20

    Terahertz radiation was generated with several designs of photoconductive antennas (three dipoles, a bow tie, and a coplanar strip line) fabricated on low-temperature-grown (LT) GaAs and semi-insulating (SI) GaAs, and the emission properties of the photoconductive antennas were compared with each other. The radiation spectrum of each antenna was characterized with the photoconductive sampling technique. The total radiation power was also measured by a bolometer for comparison of the relative radiation power. The radiation spectra of the LT-GaAs-based and SI-GaAs-based photoconductive antennas of the same design showed no significant difference. The pump-power dependencies of the radiation power showed saturation for higher pump intensities, which was more serious in SI-GaAs-based antennas than in LT-GaAs-based antennas. We attributed the origin of the saturation to the field screening of the photocarriers.

  18. Electromagnetic Vortex-Based Radar Imaging Using a Single Receiving Antenna: Theory and Experimental Results

    PubMed Central

    Yuan, Tiezhu; Wang, Hongqiang; Cheng, Yongqiang; Qin, Yuliang

    2017-01-01

    Radar imaging based on electromagnetic vortex can achieve azimuth resolution without relative motion. The present paper investigates this imaging technique with the use of a single receiving antenna through theoretical analysis and experimental results. Compared with the use of multiple receiving antennas, the echoes from a single receiver cannot be used directly for image reconstruction using Fourier method. The reason is revealed by using the point spread function. An additional phase is compensated for each mode before imaging process based on the array parameters and the elevation of the targets. A proof-of-concept imaging system based on a circular phased array is created, and imaging experiments of corner-reflector targets are performed in an anechoic chamber. The azimuthal image is reconstructed by the use of Fourier transform and spectral estimation methods. The azimuth resolution of the two methods is analyzed and compared through experimental data. The experimental results verify the principle of azimuth resolution and the proposed phase compensation method. PMID:28335487

  19. A robot architecture based on higher order perception loop.

    PubMed

    Chella, Antonio

    2010-01-01

    The paper discusses the self-consciousness of a robot as based on higher order perceptions of the robot itself. In this sense, the first order perceptions of the robot are the immediate perceptions of the outer world of the robot, while higher order perceptions are the robot perceptions of its own inner world. The resulting architecture based on higher order perceptions has been implemented and tested in a project regarding a robotic touristic guide acting in the Botanical Garden of the University of Palermo.

  20. Practical Application of Model-based Programming and State-based Architecture to Space Missions

    NASA Technical Reports Server (NTRS)

    Horvath, Gregory; Ingham, Michel; Chung, Seung; Martin, Oliver; Williams, Brian

    2006-01-01

    A viewgraph presentation to develop models from systems engineers that accomplish mission objectives and manage the health of the system is shown. The topics include: 1) Overview; 2) Motivation; 3) Objective/Vision; 4) Approach; 5) Background: The Mission Data System; 6) Background: State-based Control Architecture System; 7) Background: State Analysis; 8) Overview of State Analysis; 9) Background: MDS Software Frameworks; 10) Background: Model-based Programming; 10) Background: Titan Model-based Executive; 11) Model-based Execution Architecture; 12) Compatibility Analysis of MDS and Titan Architectures; 13) Integrating Model-based Programming and Execution into the Architecture; 14) State Analysis and Modeling; 15) IMU Subsystem State Effects Diagram; 16) Titan Subsystem Model: IMU Health; 17) Integrating Model-based Programming and Execution into the Software IMU; 18) Testing Program; 19) Computationally Tractable State Estimation & Fault Diagnosis; 20) Diagnostic Algorithm Performance; 21) Integration and Test Issues; 22) Demonstrated Benefits; and 23) Next Steps

  1. Practical Application of Model-based Programming and State-based Architecture to Space Missions

    NASA Technical Reports Server (NTRS)

    Horvath, Gregory; Ingham, Michel; Chung, Seung; Martin, Oliver; Williams, Brian

    2006-01-01

    A viewgraph presentation to develop models from systems engineers that accomplish mission objectives and manage the health of the system is shown. The topics include: 1) Overview; 2) Motivation; 3) Objective/Vision; 4) Approach; 5) Background: The Mission Data System; 6) Background: State-based Control Architecture System; 7) Background: State Analysis; 8) Overview of State Analysis; 9) Background: MDS Software Frameworks; 10) Background: Model-based Programming; 10) Background: Titan Model-based Executive; 11) Model-based Execution Architecture; 12) Compatibility Analysis of MDS and Titan Architectures; 13) Integrating Model-based Programming and Execution into the Architecture; 14) State Analysis and Modeling; 15) IMU Subsystem State Effects Diagram; 16) Titan Subsystem Model: IMU Health; 17) Integrating Model-based Programming and Execution into the Software IMU; 18) Testing Program; 19) Computationally Tractable State Estimation & Fault Diagnosis; 20) Diagnostic Algorithm Performance; 21) Integration and Test Issues; 22) Demonstrated Benefits; and 23) Next Steps

  2. An optically controlled phased array antenna based on single sideband polarization modulation.

    PubMed

    Zhang, Yamei; Wu, Huan; Zhu, Dan; Pan, Shilong

    2014-02-24

    A novel optically controlled phased array antenna consisting a simple optical beamforming network and an N element linear patch antenna array is proposed and demonstrated. The optical beamforming network is realized by N independent phase shifters using a shared optical single sideband (OSSB) polarization modulator together with N polarization controllers (PCs), N polarization beam splitters (PBSs) and N photodetectors (PDs). An experiment is carried out. A 4-element linear patch antenna array operating at 14 GHz and a 1 × 4 optical beamforming network (OBFN) is employed to realize the phased array antenna. The radiation patterns of the phased array antenna at -30°, 0° and 30° are achieved.

  3. A miniaturized micro strip antenna based on sinusoidal patch geometry for implantable biomedical applications

    NASA Astrophysics Data System (ADS)

    Ibrahim, Omar A.; Elwi, Taha A.; Islam, Naz E.

    2012-11-01

    A miniaturized microstrip antenna is analyzed for implantable biomedical applications. The antenna is designed using two different commercial software packages, CST Microwave Studio and HFSS, to validate the results. The proposed design operates in the WMTS frequency band. The antenna performance is tested inside the human body, Hugo model. The antenna design is readjusted to get the desired resonant frequency. The resonant frequency, bandwidth, gain, and radiation pattern of the proposed antenna are provided in this paper. Furthermore, the effect of losses inside human body due to the fat layer is recognized.

  4. The generation of simple compliance boundaries for mobile communication base station antennas using formulae for SAR estimation.

    PubMed

    Thors, B; Hansson, B; Törnevik, C

    2009-07-07

    In this paper, a procedure is proposed for generating simple and practical compliance boundaries for mobile communication base station antennas. The procedure is based on a set of formulae for estimating the specific absorption rate (SAR) in certain directions around a class of common base station antennas. The formulae, given for both whole-body and localized SAR, require as input the frequency, the transmitted power and knowledge of antenna-related parameters such as dimensions, directivity and half-power beamwidths. With knowledge of the SAR in three key directions it is demonstrated how simple and practical compliance boundaries can be generated outside of which the exposure levels do not exceed certain limit values. The conservativeness of the proposed procedure is discussed based on results from numerical radio frequency (RF) exposure simulations with human body phantoms from the recently developed Virtual Family.

  5. Cavity-based architecture to preserve quantum coherence and entanglement

    PubMed Central

    Man, Zhong-Xiao; Xia, Yun-Jie; Lo Franco, Rosario

    2015-01-01

    Quantum technology relies on the utilization of resources, like quantum coherence and entanglement, which allow quantum information and computation processing. This achievement is however jeopardized by the detrimental effects of the environment surrounding any quantum system, so that finding strategies to protect quantum resources is essential. Non-Markovian and structured environments are useful tools to this aim. Here we show how a simple environmental architecture made of two coupled lossy cavities enables a switch between Markovian and non-Markovian regimes for the dynamics of a qubit embedded in one of the cavity. Furthermore, qubit coherence can be indefinitely preserved if the cavity without qubit is perfect. We then focus on entanglement control of two independent qubits locally subject to such an engineered environment and discuss its feasibility in the framework of circuit quantum electrodynamics. With up-to-date experimental parameters, we show that our architecture allows entanglement lifetimes orders of magnitude longer than the spontaneous lifetime without local cavity couplings. This cavity-based architecture is straightforwardly extendable to many qubits for scalability. PMID:26351004

  6. Next Generation Image-Based Phenotyping of Root System Architecture

    NASA Astrophysics Data System (ADS)

    Davis, T. W.; Shaw, N. M.; Cheng, H.; Larson, B. G.; Craft, E. J.; Shaff, J. E.; Schneider, D. J.; Piñeros, M. A.; Kochian, L. V.

    2016-12-01

    The development of the Plant Root Imaging and Data Acquisition (PRIDA) hardware/software system enables researchers to collect digital images, along with all the relevant experimental details, of a range of hydroponically grown agricultural crop roots for 2D and 3D trait analysis. Previous efforts of image-based root phenotyping focused on young cereals, such as rice; however, there is a growing need to measure both older and larger root systems, such as those of maize and sorghum, to improve our understanding of the underlying genetics that control favorable rooting traits for plant breeding programs to combat the agricultural risks presented by climate change. Therefore, a larger imaging apparatus has been prototyped for capturing 3D root architecture with an adaptive control system and innovative plant root growth media that retains three-dimensional root architectural features. New publicly available multi-platform software has been released with considerations for both high throughput (e.g., 3D imaging of a single root system in under ten minutes) and high portability (e.g., support for the Raspberry Pi computer). The software features unified data collection, management, exploration and preservation for continued trait and genetics analysis of root system architecture. The new system makes data acquisition efficient and includes features that address the needs of researchers and technicians, such as reduced imaging time, semi-automated camera calibration with uncertainty characterization, and safe storage of the critical experimental data.

  7. Cavity-based architecture to preserve quantum coherence and entanglement.

    PubMed

    Man, Zhong-Xiao; Xia, Yun-Jie; Lo Franco, Rosario

    2015-09-09

    Quantum technology relies on the utilization of resources, like quantum coherence and entanglement, which allow quantum information and computation processing. This achievement is however jeopardized by the detrimental effects of the environment surrounding any quantum system, so that finding strategies to protect quantum resources is essential. Non-Markovian and structured environments are useful tools to this aim. Here we show how a simple environmental architecture made of two coupled lossy cavities enables a switch between Markovian and non-Markovian regimes for the dynamics of a qubit embedded in one of the cavity. Furthermore, qubit coherence can be indefinitely preserved if the cavity without qubit is perfect. We then focus on entanglement control of two independent qubits locally subject to such an engineered environment and discuss its feasibility in the framework of circuit quantum electrodynamics. With up-to-date experimental parameters, we show that our architecture allows entanglement lifetimes orders of magnitude longer than the spontaneous lifetime without local cavity couplings. This cavity-based architecture is straightforwardly extendable to many qubits for scalability.

  8. Cavity-based architecture to preserve quantum coherence and entanglement

    NASA Astrophysics Data System (ADS)

    Man, Zhong-Xiao; Xia, Yun-Jie; Lo Franco, Rosario

    2015-09-01

    Quantum technology relies on the utilization of resources, like quantum coherence and entanglement, which allow quantum information and computation processing. This achievement is however jeopardized by the detrimental effects of the environment surrounding any quantum system, so that finding strategies to protect quantum resources is essential. Non-Markovian and structured environments are useful tools to this aim. Here we show how a simple environmental architecture made of two coupled lossy cavities enables a switch between Markovian and non-Markovian regimes for the dynamics of a qubit embedded in one of the cavity. Furthermore, qubit coherence can be indefinitely preserved if the cavity without qubit is perfect. We then focus on entanglement control of two independent qubits locally subject to such an engineered environment and discuss its feasibility in the framework of circuit quantum electrodynamics. With up-to-date experimental parameters, we show that our architecture allows entanglement lifetimes orders of magnitude longer than the spontaneous lifetime without local cavity couplings. This cavity-based architecture is straightforwardly extendable to many qubits for scalability.

  9. Stretchable and reversibly deformable radio frequency antennas based on silver nanowires.

    PubMed

    Song, Lingnan; Myers, Amanda C; Adams, Jacob J; Zhu, Yong

    2014-03-26

    We demonstrate a class of microstrip patch antennas that are stretchable, mechanically tunable, and reversibly deformable. The radiating element of the antenna consists of highly conductive and stretchable material with screen-printed silver nanowires embedded in the surface layer of an elastomeric substrate. A 3-GHz microstrip patch antenna and a 6-GHz 2-element patch array are fabricated. Radiating properties of the antennas are characterized under tensile strain and agree well with the simulation results. The antenna is reconfigurable because the resonant frequency is a function of the applied tensile strain. The antenna is thus well suited for applications like wireless strain sensing. The material and fabrication technique reported here could be extended to achieve other types of stretchable antennas with more complex patterns and multilayer structures.

  10. Silicon-based broadband antenna for high responsivity and polarization-insensitive photodetection at telecommunication wavelengths.

    PubMed

    Lin, Keng-Te; Chen, Hsuen-Li; Lai, Yu-Sheng; Yu, Chen-Chieh

    2014-01-01

    Although the concept of using local surface plasmon resonance based nanoantenna for photodetection well below the semiconductor band edge has been demonstrated previously, the nature of local surface plasmon resonance based devices cannot meet many requirements of photodetection applications. Here we propose the concept of deep-trench/thin-metal (DTTM) active antenna that take advantage of surface plasmon resonance phenomena, three-dimensional cavity effects, and large-area metal/semiconductor junctions to effectively generate and collect hot electrons arising from plasmon decay and, thereby, increase photocurrent. The DTTM-based devices exhibited superior photoelectron conversion ability and high degrees of detection linearity under infrared light of both low and high intensity. Therefore, these DTTM-based devices have the attractive properties of high responsivity, extremely low power consumption, and polarization-insensitive detection over a broad bandwidth, suggesting great potential for use in photodetection and on-chip Si photonics in many applications of telecommunication fields.

  11. Fabrication process and noise properties of antenna-coupled microbolometers based on superconducting YBCO films

    NASA Astrophysics Data System (ADS)

    Karmanenko, S. F.; Semenov, A. A.; Khrebtov, I. A.; Leonov, V. N.; Johansen, T. H.; Galperin, Yu M.; Bobyl, A. V.; Dedoboretz, A. I.; Gaevski, M. E.; Lunev, A. V.; Suris, R. A.

    2000-03-01

    An analysis of how the detectivity and lifetime depend on the fabrication process of superconducting antenna-coupled microbolometers has been carried out. The temperature dependences of responsivity and noise equivalent power (NEP) have been estimated in terms of the thermal model. To reveal the main degradation mechanism, 1/f -noise characterization has been used. Monte-Carlo simulation of the annealing procedure of YBa2 Cu3 O7 (YBCO) films for the operating ranges of frequency and temperature has shown that prevailing sources of flicker noise in superconducting microstrips are associated with transitions of oxygen atoms situated close to low-angle boundaries of the film blocks. The magnetron sputtering technique has been optimized to reduce the Hooge parameter for flicker noise to a record-breaking low value for YBCO films of about 10-4 at 93 K. Comparative analysis of chemical, ion and laser etching techniques by low-temperature scanning electron microscopy and magneto-optics allowed the fabrication of microstrips with uniform current distribution characterized by critical current density higher than 106 A cm-2 at 77 K and long-time stability. The process of low-energy ion milling of YBCO films with an Ar+ beam generated in a duopigatron ion source was used to reach a width resolution at the topology edge better than 0.2 µm. The antenna-coupled bolometers fabricated from the superconducting microstrips were used to register microwave radiation at a frequency of 70.3 GHz and temperature of 93 K. It is demonstrated that the developed technology makes possible the fabrication of long-lived YBCO-based antenna microbolometers with electrical NEPe = 1.5 × 10-12 W Hz-1/2 . The calculated response time of the antenna is about 30-150 ns. Further development is associated with fabrication of coupling microbolometers with immersed lens, with predicted optical detectivity D * = (4 × 109 - 4 × 1010 ) cm Hz1/2 W-1 in the wavelength range 100-1000 µm.

  12. Deployable antenna

    NASA Technical Reports Server (NTRS)

    Fink, Patrick W. (Inventor); Dobbins, Justin A. (Inventor); Lin, Greg Y. (Inventor); Chu, Andrew W. (Inventor); Scully, Robert C. (Inventor)

    2006-01-01

    A deployable antenna and method for using wherein the deployable antenna comprises a collapsible membrane having at least one radiating element for transmitting electromagnetic waves, receiving electromagnetic waves, or both.

  13. User Antennas

    NASA Technical Reports Server (NTRS)

    Jamnejad, Vahraz; Cramer, Paul

    1990-01-01

    The following subject areas are covered: (1) impact of frequency change of user and spacecraft antenna gain and size; (2) basic personal terminal antennas (impact of 20/30 GHz frequency separation; parametric studies - gain, size, weight; gain and figure of merit (G/T); design data for selected antenna concepts; critical technologies and development goals; and recommendations); and (3) user antenna radiation safety concerns.

  14. A modern control theory based algorithm for control of the NASA/JPL 70-meter antenna axis servos

    NASA Technical Reports Server (NTRS)

    Hill, R. E.

    1987-01-01

    A digital computer-based state variable controller was designed and applied to the 70-m antenna axis servos. The general equations and structure of the algorithm and provisions for alternate position error feedback modes to accommodate intertarget slew, encoder referenced tracking, and precision tracking modes are descibed. Development of the discrete time domain control model and computation of estimator and control gain parameters based on closed loop pole placement criteria are discussed. The new algorithm was successfully implemented and tested in the 70-m antenna at Deep Space Network station 63 in Spain.

  15. Effect of space environment on space-based radar phased-array antenna (A0133)

    NASA Technical Reports Server (NTRS)

    Delasi, R. J.; Rossi, M. L.; Whiteside, J. B.; Kesselman, M.; Heuer, R. L.; Kuehne, F. J.

    1984-01-01

    Kapton polyimide film was selected as the baseline material for the Grumman spce based radar (SBR) concept. To gain the requisite confidence for long-term service durability, it is desirable to subject material specimens as well as a portion of the SBR antenna directly to the combined space environment and compare property degradation to that caused by laboratory simulation. The overall objective of this program is to evauate the effect of the space environment on polymeric materials currently being considered for the Grumman SBR Phased-Array Antenna. Degradation mechanisms caused by thermal cycling, ultraviolet and charged-particle irradiation, applied load, and high-voltage plasma interaction will be evaluated. The experiment occupies a 6-in.-deep end corner tray located on the space end of the Long Duration Exposure Facility and consists of both passive and active parts. The passive part addresses the effect of environment and stress on the dimensional stability spliced and continuous Kapton, both plain and reinforced. The active part will study the interaction of high voltage and low-Earth-orbit plasma.

  16. Terahertz real-time imaging uncooled array based on antenna- and cavity-coupled bolometers.

    PubMed

    Simoens, François; Meilhan, Jérôme

    2014-03-28

    The development of terahertz (THz) applications is slowed down by the availability of affordable, easy-to-use and highly sensitive detectors. CEA-Leti took up this challenge by tailoring the mature infrared (IR) bolometer technology for optimized THz sensing. The key feature of these detectors relies on the separation between electromagnetic absorption and the thermometer. For each pixel, specific structures of antennas and a resonant quarter-wavelength cavity couple efficiently the THz radiation on a broadband range, while a central silicon microbridge bolometer resistance is read out by a complementary metal oxide semiconductor circuit. 320×240 pixel arrays have been designed and manufactured: a better than 30 pW power direct detection threshold per pixel has been demonstrated in the 2-4 THz range. Such performance is expected on the whole THz range by proper tailoring of the antennas while keeping the technological stack largely unchanged. This paper gives an overview of the developed bolometer-based technology. First, it describes the technology and reports the latest performance characterizations. Then imaging demonstrations are presented, such as real-time reflectance imaging of a large surface of hidden objects and THz time-domain spectroscopy beam two-dimensional profiling. Finally, perspectives of camera integration for scientific and industrial applications are discussed.

  17. Wavelet-Based DFT calculations on Massively Parallel Hybrid Architectures

    NASA Astrophysics Data System (ADS)

    Genovese, Luigi

    2011-03-01

    In this contribution, we present an implementation of a full DFT code that can run on massively parallel hybrid CPU-GPU clusters. Our implementation is based on modern GPU architectures which support double-precision floating-point numbers. This DFT code, named BigDFT, is delivered within the GNU-GPL license either in a stand-alone version or integrated in the ABINIT software package. Hybrid BigDFT routines were initially ported with NVidia's CUDA language, and recently more functionalities have been added with new routines writeen within Kronos' OpenCL standard. The formalism of this code is based on Daubechies wavelets, which is a systematic real-space based basis set. As we will see in the presentation, the properties of this basis set are well suited for an extension on a GPU-accelerated environment. In addition to focusing on the implementation of the operators of the BigDFT code, this presentation also relies of the usage of the GPU resources in a complex code with different kinds of operations. A discussion on the interest of present and expected performances of Hybrid architectures computation in the framework of electronic structure calculations is also adressed.

  18. FPGA-based architecture for hyperspectral endmember extraction

    NASA Astrophysics Data System (ADS)

    Rosário, João.; Nascimento, José M. P.; Véstias, Mário

    2014-10-01

    Hyperspectral instruments have been incorporated in satellite missions, providing data of high spectral resolution of the Earth. This data can be used in remote sensing applications, such as, target detection, hazard prevention, and monitoring oil spills, among others. In most of these applications, one of the requirements of paramount importance is the ability to give real-time or near real-time response. Recently, onboard processing systems have emerged, in order to overcome the huge amount of data to transfer from the satellite to the ground station, and thus, avoiding delays between hyperspectral image acquisition and its interpretation. For this purpose, compact reconfigurable hardware modules, such as field programmable gate arrays (FPGAs) are widely used. This paper proposes a parallel FPGA-based architecture for endmember's signature extraction. This method based on the Vertex Component Analysis (VCA) has several advantages, namely it is unsupervised, fully automatic, and it works without dimensionality reduction (DR) pre-processing step. The architecture has been designed for a low cost Xilinx Zynq board with a Zynq-7020 SoC FPGA based on the Artix-7 FPGA programmable logic and tested using real hyperspectral data sets collected by the NASA's Airborne Visible Infra-Red Imaging Spectrometer (AVIRIS) over the Cuprite mining district in Nevada. Experimental results indicate that the proposed implementation can achieve real-time processing, while maintaining the methods accuracy, which indicate the potential of the proposed platform to implement high-performance, low cost embedded systems, opening new perspectives for onboard hyperspectral image processing.

  19. Architectures for parallel DSP-based adaptive optics feedback control

    NASA Astrophysics Data System (ADS)

    McCarthy, Daniel F.

    1999-11-01

    We have developed a digital image processing system for real-time digital image processing feedback control of adaptive optics systems and simulation of optical image processing algorithms. The system uses multi-computer architecture to capture data from an imaging device such as a charge coupled device camera, process the image data, and control a spatial light-modulator, typically a liquid crystal modulator or a micro-electro mechanical system. The system is a Windows NT Pentium-based system combined with a commercial off-the-shelf peripheral component interconnect bus multi-processor system. The multi-processor is based on the Analog Devices super Harvard architecture computer (SHARC) processor, and field programmable gate arrays (FPGAs). The SHARCs provide a scalable reconfigurable C language-based digital signal processing (DSP) development environment. The FPGAs are typically used as reprogrammable interface controllers designed to integrate several off-the- shelf and custom imagers and light modulators into the system. The FPGAs can also be used in concert with the SHARCs for implementation of application-specific high-speed DSP algorithms.

  20. Ku- and Ka-Band Phased Array Antenna for the Space-Based Telemetry and Range Safety Project

    NASA Technical Reports Server (NTRS)

    Whiteman, Donald E.; Valencia, Lisa M.; Birr, Richard B.

    2005-01-01

    The National Aeronautics and Space Administration Space-Based Telemetry and Range Safety study is a multiphase project to increase data rates and flexibility and decrease costs by using space-based communications assets for telemetry during launches and landings. Phase 1 used standard S-band antennas with the Tracking and Data Relay Satellite System to obtain a baseline performance. The selection process and available resources for Phase 2 resulted in a Ku-band phased array antenna system. Several development efforts are under way for a Ka-band phased array antenna system for Phase 3. Each phase includes test flights to demonstrate performance and capabilities. Successful completion of this project will result in a set of communications requirements for the next generation of launch vehicles.

  1. Space-Based Telemetry and Range Safety Project Ku-Band and Ka-Band Phased Array Antenna

    NASA Technical Reports Server (NTRS)

    Whiteman, Donald E.; Valencia, Lisa M.; Birr, Richard B.

    2005-01-01

    The National Aeronautics and Space Administration Space-Based Telemetry and Range Safety study is a multiphase project to increase data rates and flexibility and decrease costs by using space-based communications assets for telemetry during launches and landings. Phase 1 used standard S-band antennas with the Tracking and Data Relay Satellite System to obtain a baseline performance. The selection process and available resources for Phase 2 resulted in a Ku-band phased array antenna system. Several development efforts are under way for a Ka-band phased array antenna system for Phase 3. Each phase includes test flights to demonstrate performance and capabilities. Successful completion of this project will result in a set of communications requirements for the next generation of launch vehicles.

  2. Design of a radar system based on compact cavity-backed ultra wide band slot antennas for ground penetrating applications

    NASA Astrophysics Data System (ADS)

    Sagnard, F.

    2012-04-01

    ground, and coated with an inner layered absorbing material has been added to eliminate undesirable reflections from the upper environment particularly at low frequencies; moreover, in a GPR system, the antenna shielding will allow to reduce the coupling between the transmitting and the receiving units. The proposed rectangular slot antenna has been designed and simulated using the 3D commercial software EMPIRE based on the finite difference time domain (FDTD) technique. A detailed parameter study has allowed to define the several geometrical parameters of the unshielded slot antenna which are the result of a compromise on the frequency bandwidth (S11<-10 dB) and compact dimensions. Afterwards, the antenna radiation characteristics have been studied in the presence of a shield (conductive box coated with a multi-layered lossy material) and a common soil (epsilon=5.5, sigma=0.01 S/m). A pair of antennas has then been considered to form a bistatic radar link positioned on the soil surface, where the soil can included buried objects (pipe or crack) met in civil engineering structures. First measurements made on a sandy box have allowed to validate the simulation results

  3. A New Dielectric Resonator Antenna Operating with Magneto-Dielectric Materials Based in Y3FE5-2xBIxBx Garnets

    DTIC Science & Technology

    2010-02-28

    80 (2009) 055706-055710 (IOP) 11 - Study of a microwave ferrite resonator antenna , based in a ferrimagnetic composite (Gd3Fe5012)GdIGX-( Y3Fe5012...fernte composite, a bulk cylindrical geometry was also investigated 15. SUBJECT TERMS DIELECTRIC RESONATOR ANTENNA . RADAR. FERRITES 16. SECURITY...cylindrical ceramic bulk ferrite resonator antennas . In the RF range, we observed that the material is rather stable because of its small changes as a

  4. Yagi-Uda optical antenna array collimated laser based on surface plasmons

    NASA Astrophysics Data System (ADS)

    Ma, Long; Lin, Jie; Ma, Yuan; Liu, Bin; Tan, Jiubin; Jin, Peng

    2016-06-01

    The divergence and directivity of a laser with a periodic Yagi-Uda optical antenna array modulated surface are investigated by finite element method. The nanoparticle optical antenna arrays are optimized to achieve the high directivity and the small divergence by using of Helmholtz's reciprocity theorem. When the nanoparticle antenna replaced by a Yagi-Uda antenna with same size, the directivity and the signal-to-noise ratio of the modulated laser beam are notably enhanced. The main reason is that the directors of the Yagi-Uda antennas induce more energy to propagate towards the antenna transmitting direction. The results can provide valuable guidelines in designing collimated laser, which can be widely applied in the field of biologic detection, spatial optical communication and optical measurement.

  5. Attitude and vibration control of a large flexible space-based antenna

    NASA Technical Reports Server (NTRS)

    Joshi, S. M.; Goglia, G. L.

    1982-01-01

    The problem of control systems synthesis is considered for controlling the rigid body attitude and elastic motion of a large deployable space based antenna. Two methods for control systems synthesis are considered. The first method utilizes the stability and robustness properties of the controller consisting of torque actuators and collocated attitude and rate sensors. The second method is based on the linear quadratic Gaussian (LQG) control theory. A combination of the two methods, which results in a two level hierarchical control system, is also briefly discussed. The performance of the controllers is analyzed by computing the variances of pointing errors, feed misalignment errors and surface contour errors in the presence of sensor and actuator noise.

  6. Human friendly architectural design for a small Martian base

    NASA Astrophysics Data System (ADS)

    Kozicki, J.; Kozicka, J.

    2011-12-01

    The manned mission to Mars is expected to last almost three years. A human factor must be taken seriously into account in such a long-term mission. A big comfortable habitat can help to overcome sociopsychological problems, that occur in ICEs (Isolated and Confined Environments). Authors have come forward to this issue and have developed a Martian base design as a human friendly habitat. The project is based on researches of extreme conditions on Mars, architecture in ICEs and contemporary building technologies. The base consists of five modules: a Central Module (CM), an Agriculture Dome (AD), a Residential Dome (RD), a Laboratory Dome (LD) and a Garage (G). Each element has its own functional purpose. The CM is a metal capsule similar to the Reference Mission module (RM, NASA, 1997). Domes are inflatable multilayer structures, which interiors are "open planned". Interiors can be arranged and divided into rooms by using modular partition walls designed by authors.

  7. A reinforcement learning-based architecture for fuzzy logic control

    NASA Technical Reports Server (NTRS)

    Berenji, Hamid R.

    1992-01-01

    This paper introduces a new method for learning to refine a rule-based fuzzy logic controller. A reinforcement learning technique is used in conjunction with a multilayer neural network model of a fuzzy controller. The approximate reasoning based intelligent control (ARIC) architecture proposed here learns by updating its prediction of the physical system's behavior and fine tunes a control knowledge base. Its theory is related to Sutton's temporal difference (TD) method. Because ARIC has the advantage of using the control knowledge of an experienced operator and fine tuning it through the process of learning, it learns faster than systems that train networks from scratch. The approach is applied to a cart-pole balancing system.

  8. A reinforcement learning-based architecture for fuzzy logic control

    NASA Technical Reports Server (NTRS)

    Berenji, Hamid R.

    1992-01-01

    This paper introduces a new method for learning to refine a rule-based fuzzy logic controller. A reinforcement learning technique is used in conjunction with a multilayer neural network model of a fuzzy controller. The approximate reasoning based intelligent control (ARIC) architecture proposed here learns by updating its prediction of the physical system's behavior and fine tunes a control knowledge base. Its theory is related to Sutton's temporal difference (TD) method. Because ARIC has the advantage of using the control knowledge of an experienced operator and fine tuning it through the process of learning, it learns faster than systems that train networks from scratch. The approach is applied to a cart-pole balancing system.

  9. A knowledge base architecture for distributed knowledge agents

    NASA Technical Reports Server (NTRS)

    Riedesel, Joel; Walls, Bryan

    1990-01-01

    A tuple space based object oriented model for knowledge base representation and interpretation is presented. An architecture for managing distributed knowledge agents is then implemented within the model. The general model is based upon a database implementation of a tuple space. Objects are then defined as an additional layer upon the database. The tuple space may or may not be distributed depending upon the database implementation. A language for representing knowledge and inference strategy is defined whose implementation takes advantage of the tuple space. The general model may then be instantiated in many different forms, each of which may be a distinct knowledge agent. Knowledge agents may communicate using tuple space mechanisms as in the LINDA model as well as using more well known message passing mechanisms. An implementation of the model is presented describing strategies used to keep inference tractable without giving up expressivity. An example applied to a power management and distribution network for Space Station Freedom is given.

  10. Transputer-based architecture for ATM LAN protocol testing

    NASA Astrophysics Data System (ADS)

    Di Concetto, M.; Crocetti, P.; Marino, G.; Merli, E.; Pavesi, M.; Zizza, F.

    1993-10-01

    Local Area Networks (LANs) have completed two generations of development (Ethernet and Token Ring the first, and FDDI and DQDB the second); the large volumes of traffic involved in the emerging multimedia applications, however, lead towards a third generation of LANs. This generation must provide real-time capabilities needed by new services and solve the problems of interworking with ATM-based B-ISDN. Moreover the possibility to vary the subscribed bandwidth with the B-ISDN will be given to the LAN interfaces. This paper focuses on an architecture for protocol testing of a Dynamic Bandwidth Allocation Protocol inserted in a LAN environment based on ATM technology. In fact, the technology of the third LAN generation will be the Asynchronous Transfer Mode solving every interface problem with the public B-ISDN. A testing and debugging environment which checks the implementation of the Dynamic Bandwidth Allocation Protocol at the interface host/LAN- ATM is discussed. The main concepts of the overall system architecture are analyzed, evidencing both software and hardware issues.

  11. Parallel PDE-Based Simulations Using the Common Component Architecture

    SciTech Connect

    McInnes, Lois C.; Allan, Benjamin A.; Armstrong, Robert; Benson, Steven J.; Bernholdt, David E.; Dahlgren, Tamara L.; Diachin, Lori; Krishnan, Manoj Kumar; Kohl, James A.; Larson, J. Walter; Lefantzi, Sophia; Nieplocha, Jarek; Norris, Boyana; Parker, Steven G.; Ray, Jaideep; Zhou, Shujia

    2006-03-05

    Summary. The complexity of parallel PDE-based simulations continues to increase as multimodel, multiphysics, and multi-institutional projects become widespread. A goal of componentbased software engineering in such large-scale simulations is to help manage this complexity by enabling better interoperability among various codes that have been independently developed by different groups. The Common Component Architecture (CCA) Forum is defining a component architecture specification to address the challenges of high-performance scientific computing. In addition, several execution frameworks, supporting infrastructure, and generalpurpose components are being developed. Furthermore, this group is collaborating with others in the high-performance computing community to design suites of domain-specific component interface specifications and underlying implementations. This chapter discusses recent work on leveraging these CCA efforts in parallel PDE-based simulations involving accelerator design, climate modeling, combustion, and accidental fires and explosions. We explain how component technology helps to address the different challenges posed by each of these applications, and we highlight how component interfaces built on existing parallel toolkits facilitate the reuse of software for parallel mesh manipulation, discretization, linear algebra, integration, optimization, and parallel data redistribution. We also present performance data to demonstrate the suitability of this approach, and we discuss strategies for applying component technologies to both new and existing applications.

  12. A Space Based Radar Antenna Concept to Counter Camouflage and Concealment

    DTIC Science & Technology

    2006-09-07

    design options already in use for higher frequency SAR antennas include slotted waveguide (ERS-1 and 2 and Radarsat-1) and active phased arrays (ASAR...operating at P-Band or below can adequate penetration of these forests be achieved. The antenna is designed to be used from a spacecraft in a low ...Earth orbit. The antenna design has a monolithic array of feed and radiating patches bonded to a transversally curved structure consisting of two Kevlar

  13. Model based design introduction: modeling game controllers to microprocessor architectures

    NASA Astrophysics Data System (ADS)

    Jungwirth, Patrick; Badawy, Abdel-Hameed

    2017-04-01

    We present an introduction to model based design. Model based design is a visual representation, generally a block diagram, to model and incrementally develop a complex system. Model based design is a commonly used design methodology for digital signal processing, control systems, and embedded systems. Model based design's philosophy is: to solve a problem - a step at a time. The approach can be compared to a series of steps to converge to a solution. A block diagram simulation tool allows a design to be simulated with real world measurement data. For example, if an analog control system is being upgraded to a digital control system, the analog sensor input signals can be recorded. The digital control algorithm can be simulated with the real world sensor data. The output from the simulated digital control system can then be compared to the old analog based control system. Model based design can compared to Agile software develop. The Agile software development goal is to develop working software in incremental steps. Progress is measured in completed and tested code units. Progress is measured in model based design by completed and tested blocks. We present a concept for a video game controller and then use model based design to iterate the design towards a working system. We will also describe a model based design effort to develop an OS Friendly Microprocessor Architecture based on the RISC-V.

  14. Architectures for a Space-based Gravitational-Wave Observatory

    NASA Astrophysics Data System (ADS)

    Stebbins, Robin

    2015-04-01

    The European Space Agency (ESA) selected the science theme, the ``Gravitational Universe,'' for the third large mission opportunity, known as L3, under its Cosmic Vision Programme. The planned launch date is 2034. ESA is considering a 20% participation by an international partner, and NASA's Astrophysics Division has begun negotiating a NASA role. We have studied the design consequences of a NASA contribution, evaluated the science benefits and identified the technology requirements for hardware that could be delivered by NASA. The European community proposed a strawman mission concept, called eLISA, having two measurement arms, derived from the well studied LISA (Laser Interferometer Space Antenna) concept. The US community is promoting a mission concept known as SGO Mid (Space-based Gravitational-wave Observatory Mid-sized), a three arm LISA-like concept. If NASA were to partner with ESA, the eLISA concept could be transformed to SGO Mid by the addition of a third arm, thereby augmenting science, reducing risk and reducing non-recurring engineering costs. The characteristics of the mission concepts and the relative science performance of eLISA, SGO Mid and LISA are described.

  15. Metal-insulator-metal antennas in the far-infrared range based on highly doped InAsSb

    NASA Astrophysics Data System (ADS)

    Omeis, F.; Smaali, R.; Gonzalez-Posada, F.; Cerutti, L.; Taliercio, T.; Centeno, E.

    2017-09-01

    Plasmonic behavior in the far-infrared (IR) and terahertz (THz) ranges can facilitate a lot of applications in communication, imaging or sensing, security, and biomedical domains. However, simple scaling laws cannot be applied to design noble metal-based plasmonic systems operating at far-IR or THz frequencies. To overcome this issue, we numerically and experimentally explore the plasmonic properties in the spectral range between 25 and 40 μm (12 and 7.5 THz) of metal-insulator-metal (MIM) antennas made of InAsSb a highly Si-doped semiconductor. We demonstrate that these MIM antennas sustain a gap plasmon mode that is responsible for high light absorption. By tracking this peculiar plasmonic signature for various antennas' widths, we prove that Si-doped InAsSb microstructures realized on large areas by laser lithography and the wet etching process are a low cost, reproducible, and readily CMOS compatible approach.

  16. GPS-based real-time attitude determination for a moving platform using three-antenna technology

    NASA Astrophysics Data System (ADS)

    Ren, Chao; Lu, Xianjian; Hu, Guorong

    2015-12-01

    GPS has been used successfully to determine attitude for a moving platform. A direct calculation method of real-time attitude determination using three-antenna system for the moving platform is described. Since real-time integer ambiguity resolution for baseline vectors is a key process for a high accuracy real-time attitude determination, the ambiguity resolution method and validation test procedure epoch-by-epoch are proposed based on the special property of the three-antenna system. Simulation study results are presented in this contribution showing that better than one degree accuracy of the platform attitude can be achieved using the proposed method.

  17. Left-handed compact MIMO antenna array based on wire spiral resonator for 5-GHz wireless applications

    NASA Astrophysics Data System (ADS)

    Alqadami, Abdulrahman Shueai Mohsen; Jamlos, Mohd Faizal; Soh, Ping Jack; Rahim, Sharul Kamal Abdul; Narbudowicz, Adam

    2017-01-01

    A compact coplanar waveguide-fed multiple-input multiple-output antenna array based on the left-handed wire loaded spiral resonators (SR) is presented. The proposed antenna consists of a 2 × 2 wire SR with two symmetrical microstrip feed lines, each line exciting a 1 × 2 wire SR. Left-handed metamaterial unit cells are placed on its reverse side and arranged in a 2 × 3 array. A reflection coefficient of less than -16 dB and mutual coupling of less than -28 dB are achieved at 5.15 GHz WLAN band.

  18. Web based aphasia test using service oriented architecture (SOA)

    NASA Astrophysics Data System (ADS)

    Voos, J. A.; Vigliecca, N. S.; Gonzalez, E. A.

    2007-11-01

    Based on an aphasia test for Spanish speakers which analyze the patient's basic resources of verbal communication, a web-enabled software was developed to automate its execution. A clinical database was designed as a complement, in order to evaluate the antecedents (risk factors, pharmacological and medical backgrounds, neurological or psychiatric symptoms, brain injury -anatomical and physiological characteristics, etc) which are necessary to carry out a multi-factor statistical analysis in different samples of patients. The automated test was developed following service oriented architecture and implemented in a web site which contains a tests suite, which would allow both integrating the aphasia test with other neuropsychological instruments and increasing the available site information for scientific research. The test design, the database and the study of its psychometric properties (validity, reliability and objectivity) were made in conjunction with neuropsychological researchers, who participate actively in the software design, based on the patients or other subjects of investigation feedback.

  19. Reconfigurable antenna pattern verification

    NASA Technical Reports Server (NTRS)

    Drexler, Jerome P. (Inventor); Becker, Robert C. (Inventor); Meyers, David W. (Inventor); Muldoon, Kelly P. (Inventor)

    2013-01-01

    A method of verifying programmable antenna configurations is disclosed. The method comprises selecting a desired antenna configuration from a plurality of antenna configuration patterns, with the selected antenna configuration forming at least one reconfigurable antenna from reconfigurable antenna array elements. The method validates the formation of the selected antenna configuration to determine antenna performance of the at least one reconfigurable antenna.

  20. Broadband integrated band-stop filter for horn antennas based on coupled SRRs

    NASA Astrophysics Data System (ADS)

    Barbuto, Mirko; Bilotti, Filiberto; Toscano, Alessandro

    2016-06-01

    In this contribution, inspired by a common phenomenon that is well-known in circuit theory, we show a simple method to increase the bandwidth of a band-stop filter based on the use of split-ring resonators (SRRs). In particular, the basic structure of the filtering module consists of a single SRR placed inside a pyramidal horn to implement a self-filtering antenna with a notched-band behavior. In order to increase the rejected band, we placed a second identical SRR in close proximity with the previous one. If the distance between the SRRs is suitably chosen, the two resonators are properly coupled leading to a widening of the notched-band of the filtering module. The effectiveness of the proposed approach is confirmed by the results of full-wave numerical simulations.

  1. 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

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

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

    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.

  3. Omnidirectional antenna for radar applications

    NASA Astrophysics Data System (ADS)

    Vitiello, R.

    The development of an omnidirectional antenna for sidelobe blanking is described. The results of electrical measurements for an S-band and L-band configuration are given. The antenna architecture consists of eight printed radiating elements arranged in a biconical fashion. The single radiating element is a pseudo log periodic microstrip array fed by means of capacitive coupling. Modularity and flexibility are the outstanding characteristics of the design.

  4. Horn antenna design studies. Citations from the International Aerospace Abstract data base

    NASA Technical Reports Server (NTRS)

    Gallagher, M. K.

    1980-01-01

    These citations from the international literature describe the antenna radiation patterns, polarization characteristics, wave propagation, noise temperature, wave diffraction, and wideband communication of various horn antennas. This updated bibliography contains 217 citations, 63 of which are new entries to the previous edition.

  5. Proposal of an Arc Detection Technique Based on RF Measurements for the ITER ICRF Antenna

    SciTech Connect

    Huygen, S.; Dumortier, P.; Durodie, F.; Messiaen, A.; Vervier, M.; Vrancken, M.

    2011-12-23

    RF arc detection is a key operational and safety issue for the ICRF system on ITER. Indeed the high voltages inside the antenna put it at risk of arcing, which could cause substantial damage. This paper describes the various possibilities explored by circuit simulation and the strategy now considered to protect the ITER ICRF antenna from RF arcs.

  6. Optical antennas as nanoscale resonators.

    PubMed

    Agio, Mario

    2012-02-07

    Recent progress in nanotechnology has enabled us to fabricate sub-wavelength architectures that function as antennas for improving the exchange of optical energy with nanoscale matter. We describe the main features of optical antennas for enhancing quantum emitters and review the designs that increase the spontaneous emission rate by orders of magnitude from the ultraviolet up to the near-infrared spectral range. To further explore how optical antennas may lead to unprecedented regimes of light-matter interactions, we draw a relationship between metal nanoparticles, radio-wave antennas and optical resonators. Our analysis points out how optical antennas may function as nanoscale resonators and how these may offer unique opportunities with respect to state-of-the-art microcavities.

  7. Resonance-Based Reflector and Its Application in Unidirectional Antenna with Low-Profile and Broadband Characteristics for Wireless Applications

    PubMed Central

    Peng, Lin; Xie, Ji-yang; Sun, Kai; Jiang, Xing; Li, Si-min

    2016-01-01

    In this research, the novel concept of a resonance-based reflector (RBR) was proposed, and a ring-shaped RBR was utilized to design a unidirectional antenna with low-profile and broadband characteristics. Research found the ring operates as two half-wavelength (λ/2) resonators. Then, the resonance effect transforms the reflection phase of the ring RBR, and achieves a reflection phase of 0° < ϕ < 180° in a wide frequency range above the resonance. Then, the in-phase reflection characteristic (−90° < ϕ < 90°) can be obtained in the wide frequency band by placing an antenna above the RBR with a distance smaller than λ/4. Two unidirectional antennas, named Case 1 and Case 2, were designed with the ring-shaped RBRs and bowtie antennas (RBR-BAs). The impedance bandwidths of Case 1 and the Case 2 are 2.04–5.12 GHz (86.3%) and 1.97–5.01 GHz (87.1%), respectively. The front-to-back ratio (FBR, an important parameter to measure the unidirectional radiation) of Case 1 ranges from 5–9.9 dB for frequencies 2.04–2.42 GHz, and the FBR of Case 2 ranges from 5–16 dB for frequencies 2.16–3.15 GHz. The proposed concept of RBR is desirable in wideband unidirectional antenna design, and the designing antennas can be used at the front end of wireless systems—such as indoors communication, remote sensing, and wireless sensor systems—for signal receiving or transmitting. PMID:27941702

  8. Resonance-Based Reflector and Its Application in Unidirectional Antenna with Low-Profile and Broadband Characteristics for Wireless Applications.

    PubMed

    Peng, Lin; Xie, Ji-Yang; Sun, Kai; Jiang, Xing; Li, Si-Min

    2016-12-09

    In this research, the novel concept of a resonance-based reflector (RBR) was proposed, and a ring-shaped RBR was utilized to design a unidirectional antenna with low-profile and broadband characteristics. Research found the ring operates as two half-wavelength (λ/2) resonators. Then, the resonance effect transforms the reflection phase of the ring RBR, and achieves a reflection phase of 0° < ϕ < 180° in a wide frequency range above the resonance. Then, the in-phase reflection characteristic (-90° < ϕ < 90°) can be obtained in the wide frequency band by placing an antenna above the RBR with a distance smaller than λ/4. Two unidirectional antennas, named Case 1 and Case 2, were designed with the ring-shaped RBRs and bowtie antennas (RBR-BAs). The impedance bandwidths of Case 1 and the Case 2 are 2.04-5.12 GHz (86.3%) and 1.97-5.01 GHz (87.1%), respectively. The front-to-back ratio (FBR, an important parameter to measure the unidirectional radiation) of Case 1 ranges from 5-9.9 dB for frequencies 2.04-2.42 GHz, and the FBR of Case 2 ranges from 5-16 dB for frequencies 2.16-3.15 GHz. The proposed concept of RBR is desirable in wideband unidirectional antenna design, and the designing antennas can be used at the front end of wireless systems-such as indoors communication, remote sensing, and wireless sensor systems-for signal receiving or transmitting.

  9. Wide Field-of-view and Broadband Terahertz Beam Steering Based on Gap Plasmon Geodesic Antennas

    NASA Astrophysics Data System (ADS)

    Liu, Kaipeng; Guo, Yinghui; Pu, Mingbo; Ma, Xiaoliang; Li, Xiong; Luo, Xiangang

    2017-01-01

    Despite a plethora of applications ranging from wireless communications to sensing and spectroscopy, the current terahertz beam steering technologies suffer from tremendous insert loss, stringent control of electric bias, limited scanning angle, relatively complicated configuration and narrow operation bandwidth, preventing further practical application. We propose and demonstrate a conceptually new approach for terahertz beam steering by virtue of gap plasmon geodesic antennas. By adjusting the geometric dimension of the gap plasmon geodesic antennas, all gap plasmon modes add coherently along a peculiar direction that depends on the geodesic mean surface. Consequently, high directive beams are generated through the antenna, whose direction could be changed within a wide-angle range spanning ±45° by lateral motion of the feed. Furthermore, an assembled antenna structure consisting of four-element geodesic antennas array is proposed for full 360° beam steering, which can operate in a broadband range from 0.8 THz to 1.2 THz.

  10. Wide Field-of-view and Broadband Terahertz Beam Steering Based on Gap Plasmon Geodesic Antennas.

    PubMed

    Liu, Kaipeng; Guo, Yinghui; Pu, Mingbo; Ma, Xiaoliang; Li, Xiong; Luo, Xiangang

    2017-01-30

    Despite a plethora of applications ranging from wireless communications to sensing and spectroscopy, the current terahertz beam steering technologies suffer from tremendous insert loss, stringent control of electric bias, limited scanning angle, relatively complicated configuration and narrow operation bandwidth, preventing further practical application. We propose and demonstrate a conceptually new approach for terahertz beam steering by virtue of gap plasmon geodesic antennas. By adjusting the geometric dimension of the gap plasmon geodesic antennas, all gap plasmon modes add coherently along a peculiar direction that depends on the geodesic mean surface. Consequently, high directive beams are generated through the antenna, whose direction could be changed within a wide-angle range spanning ±45° by lateral motion of the feed. Furthermore, an assembled antenna structure consisting of four-element geodesic antennas array is proposed for full 360° beam steering, which can operate in a broadband range from 0.8 THz to 1.2 THz.

  11. Microelectromechanical Systems (MEMS) Actuator-Based, Polarization Reconfigurable Patch Antenna Demonstrated

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.

    2002-01-01

    A nearly square patch antenna with a contact actuator along a radiating edge for polarization reconfiguration was demonstrated at Ka-band frequencies at the NASA Glenn Research Center. The layout of the antenna is shown in the following sketch. This antenna has the following advantages: 1) It can be dynamically reconfigured to receive and transmit a linearly polarized signal or a circularly polarized signal. This feature allows the substitution of multiple antennas on a satellite by a single antenna, thereby resulting in significant cost savings. 2) In our approach, the polarization is switched between the two states without affecting the frequency of operation; thus, valuable frequency spectrum is conserved. 3) The ability to switch polarization also helps mitigate propagation effects due to adverse weather on the performance of a satellite-to-ground link. Hence, polarization reconfigurability enhances link reliability.

  12. Adaptive antennas

    NASA Astrophysics Data System (ADS)

    Barton, P.

    1987-04-01

    The basic principles of adaptive antennas are outlined in terms of the Wiener-Hopf expression for maximizing signal to noise ratio in an arbitrary noise environment; the analogy with generalized matched filter theory provides a useful aid to understanding. For many applications, there is insufficient information to achieve the above solution and thus non-optimum constrained null steering algorithms are also described, together with a summary of methods for preventing wanted signals being nulled by the adaptive system. The three generic approaches to adaptive weight control are discussed; correlation steepest descent, weight perturbation and direct solutions based on sample matrix conversion. The tradeoffs between hardware complexity and performance in terms of null depth and convergence rate are outlined. The sidelobe cancellor technique is described. Performance variation with jammer power and angular distribution is summarized and the key performance limitations identified. The configuration and performance characteristics of both multiple beam and phase scan array antennas are covered, with a brief discussion of performance factors.

  13. 47 CFR 95.51 - Antenna height.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Antenna height. 95.51 Section 95.51... SERVICES General Mobile Radio Service (GMRS) § 95.51 Antenna height. (a) Certain antenna structures used in... this chapter. (b) The antenna for a small base station or for a small control station must not be...

  14. 47 CFR 95.51 - Antenna height.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Antenna height. 95.51 Section 95.51... SERVICES General Mobile Radio Service (GMRS) § 95.51 Antenna height. (a) Certain antenna structures used in... this chapter. (b) The antenna for a small base station or for a small control station must not be...

  15. 47 CFR 95.51 - Antenna height.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Antenna height. 95.51 Section 95.51... SERVICES General Mobile Radio Service (GMRS) § 95.51 Antenna height. (a) Certain antenna structures used in... this chapter. (b) The antenna for a small base station or for a small control station must not be...

  16. 47 CFR 95.51 - Antenna height.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Antenna height. 95.51 Section 95.51... SERVICES General Mobile Radio Service (GMRS) § 95.51 Antenna height. (a) Certain antenna structures used in... this chapter. (b) The antenna for a small base station or for a small control station must not be...

  17. 47 CFR 95.51 - Antenna height.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Antenna height. 95.51 Section 95.51... SERVICES General Mobile Radio Service (GMRS) § 95.51 Antenna height. (a) Certain antenna structures used in... this chapter. (b) The antenna for a small base station or for a small control station must not be...

  18. Sensor-based architecture for medical imaging workflow analysis.

    PubMed

    Silva, Luís A Bastião; Campos, Samuel; Costa, Carlos; Oliveira, José Luis

    2014-08-01

    The growing use of computer systems in medical institutions has been generating a tremendous quantity of data. While these data have a critical role in assisting physicians in the clinical practice, the information that can be extracted goes far beyond this utilization. This article proposes a platform capable of assembling multiple data sources within a medical imaging laboratory, through a network of intelligent sensors. The proposed integration framework follows a SOA hybrid architecture based on an information sensor network, capable of collecting information from several sources in medical imaging laboratories. Currently, the system supports three types of sensors: DICOM repository meta-data, network workflows and examination reports. Each sensor is responsible for converting unstructured information from data sources into a common format that will then be semantically indexed in the framework engine. The platform was deployed in the Cardiology department of a central hospital, allowing identification of processes' characteristics and users' behaviours that were unknown before the utilization of this solution.

  19. Services oriented architecture (SOA)-based persistent ISR simulation system

    NASA Astrophysics Data System (ADS)

    Chen, Genshe; Blasch, Erik; Shen, Dan; Chen, Huimin; Pham, Khanh

    2010-04-01

    In the modern networked battlefield, network centric warfare (NCW) scenarios need to interoperate between shared resources and data assets such as sensors, UAVs, satellites, ground vehicles, and command and control (C2/C4I) systems. By linking and fusing platform routing information, sensor exploitation results, and databases (e.g. Geospatial Information Systems [GIS]), the shared situation awareness and mission effectiveness will be improved. Within the information fusion community, various research efforts are looking at open standard approaches to composing the heterogeneous network components under one framework for future modeling and simulation applications. By utilizing the open source services oriented architecture (SOA) based sensor web services, and GIS visualization services, we propose a framework that ensures the fast prototyping of intelligence, surveillance, and reconnaissance (ISR) system simulations to determine an asset mix for a desired mission effectiveness, performance modeling for sensor management and prediction, and user testing of various scenarios.

  20. Timeline-Based Mission Operations Architecture: An Overview

    NASA Technical Reports Server (NTRS)

    Chung, Seung H.; Bindschadler, Duane L.

    2012-01-01

    Some of the challenges in developing a mission operations system and operating a mission can be traced back to the challenge of integrating a mission operations system from its many components and to the challenge of maintaining consistent and accountable information throughout the operations processes. An important contributing factor to both of these challenges is the file-centric nature of today's systems. In this paper, we provide an overview of these challenges and argue the need to move toward an information-centric mission operations system. We propose an information representation called Timeline as an approach to enable such a move, and we provide an overview of a Timeline-based Mission Operations System architecture.

  1. SoC-based architecture for biomedical signal processing.

    PubMed

    Gutiérrez-Rivas, R; Hernández, A; García, J J; Marnane, W

    2015-01-01

    Over the last decades, many algorithms have been proposed for processing biomedical signals. Most of these algorithms have been focused on the elimination of noise and artifacts existing in these signals, so they can be used for automatic monitoring and/or diagnosis applications. With regard to remote monitoring, the use of portable devices often requires a reduced number of resources and power consumption, being necessary to reach a trade-off between the accuracy of algorithms and their computational complexity. This paper presents a SoC (System-on-Chip) architecture, based on a FPGA (Field-Programmable Gate Array) device, suitable for the implementation of biomedical signal processing. The proposal has been successfully validated by implementing an efficient QRS complex detector. The results show that, using a reduced amount of resources, values of sensitivity and positive predictive value above 99.49% are achieved, which make the proposed approach suitable for telemedicine applications.

  2. Branched Macromolecular Architectures for Degradable, Multifunctional Phosphorus-Based Polymers.

    PubMed

    Henke, Helena; Brüggemann, Oliver; Teasdale, Ian

    2017-02-01

    This feature article briefly highlights some of the recent advances in polymers in which phosphorus is an integral part of the backbone, with a focus on the preparation of functional, highly branched, soluble polymers. A comparison is made between the related families of materials polyphosphazenes, phosphazene/phosphorus-based dendrimers and polyphosphoesters. The work described herein shows this to be a rich and burgeoning field, rapidly catching up with organic chemistry in terms of the macromolecular synthetic control and variety of available macromolecular architectures, whilst offering unique property combinations not available with carbon backbones, such as tunable degradation rates, high multi-valency and facile post-polymerization functionalization. As an example of their use in advanced applications, we highlight some investigations into their use as water-soluble drug carriers, whereby in particular the degradability in combination with multivalent nature has made them useful materials, as underlined by some of the recent studies in this area.

  3. Low-Power Architectures for Large Radio Astronomy Correlators

    NASA Technical Reports Server (NTRS)

    D'Addario, Larry R.

    2011-01-01

    The architecture of a cross-correlator for a synthesis radio telescope with N greater than 1000 antennas is studied with the objective of minimizing power consumption. It is found that the optimum architecture minimizes memory operations, and this implies preference for a matrix structure over a pipeline structure and avoiding the use of memory banks as accumulation registers when sharing multiply-accumulators among baselines. A straw-man design for N = 2000 and bandwidth of 1 GHz, based on ASICs fabricated in a 90 nm CMOS process, is presented. The cross-correlator proper (excluding per-antenna processing) is estimated to consume less than 35 kW.

  4. Low-Power Architectures for Large Radio Astronomy Correlators

    NASA Technical Reports Server (NTRS)

    D'Addario, Larry R.

    2011-01-01

    The architecture of a cross-correlator for a synthesis radio telescope with N greater than 1000 antennas is studied with the objective of minimizing power consumption. It is found that the optimum architecture minimizes memory operations, and this implies preference for a matrix structure over a pipeline structure and avoiding the use of memory banks as accumulation registers when sharing multiply-accumulators among baselines. A straw-man design for N = 2000 and bandwidth of 1 GHz, based on ASICs fabricated in a 90 nm CMOS process, is presented. The cross-correlator proper (excluding per-antenna processing) is estimated to consume less than 35 kW.

  5. Executable Architecture Modeling and Simulation Based on fUML

    DTIC Science & Technology

    2014-06-01

    informal constructs. The paper proposes an approach of executable architecture modeling and simulation by introducing formal UML specification. Firstly...ones. UML is accepted as an Architectural Description Language by architects, and it has become a standard notation to document the architecture...these UML models are not executable. Object Management Group proposes the fUML to enable UML models execution [5]. Accordingly, we propose an

  6. Architecture-Based Refinements for Secure Computer Systems Design

    DTIC Science & Technology

    2006-01-01

    INTRODUCTION In recent years, security has been a growing concern in software engineering research, especially software architecture research. In IEEE/ANSI 830...1993, security is defined as one of the thirteen non-functional (or quality) requirements ( NFRs ) that must be included in the software requirements... software and thus cannot be presented in software architecture as components or functions offered by the system [2]. The overall software architecture

  7. Different micromanipulation applications based on common modular control architecture

    NASA Astrophysics Data System (ADS)

    Sipola, Risto; Vallius, Tero; Pudas, Marko; Röning, Juha

    2010-01-01

    This paper validates a previously introduced scalable modular control architecture and shows how it can be used to implement research equipment. The validation is conducted by presenting different kinds of micromanipulation applications that use the architecture. Conditions of the micro-world are very different from those of the macro-world. Adhesive forces are significant compared to gravitational forces when micro-scale objects are manipulated. Manipulation is mainly conducted by automatic control relying on haptic feedback provided by force sensors. The validated architecture is a hierarchical layered hybrid architecture, including a reactive layer and a planner layer. The implementation of the architecture is modular, and the architecture has a lot in common with open architectures. Further, the architecture is extensible, scalable, portable and it enables reuse of modules. These are the qualities that we validate in this paper. To demonstrate the claimed features, we present different applications that require special control in micrometer, millimeter and centimeter scales. These applications include a device that measures cell adhesion, a device that examines properties of thin films, a device that measures adhesion of micro fibers and a device that examines properties of submerged gel produced by bacteria. Finally, we analyze how the architecture is used in these applications.

  8. Flexible and reversibly deformable radio-frequency antenna based on stretchable SWCNTs/PANI/Lycra conductive fabric

    NASA Astrophysics Data System (ADS)

    Guo, Xiaohui; Huang, Ying; Wu, Can; Mao, Leidong; Wang, Yue; Xie, Zhicheng; Liu, Caixia; Zhang, Yugang

    2017-10-01

    We demonstrated a flexible and reversibly deformable radio-frequency antenna based on SWCNTs/PANI/Lycra conductive fabric and semipermeable film for wireless wearable communications applications. The conductive fabric fabricated by using the ‘dip and dry’ process exhibits good flexibility, electrical stability, stretchability and mechanical properties, and a high electrical conductivity (with low sheet resistance of ∼35 Ω/sq) was obtained based on the SWCNTs/PANI synergistic conductive network. The morphology of the semipermeable film was investigated to further illustrate the waterproof breathable features. Meanwhile, the modeling, fabrication procedure and radiating properties of the radio-frequency textile antenna worked at 2.45 GHz were systematically illustrated. The measured reflection coefficient, VSWR and the ‑10 dB bandwidth is ∼‑18.6 dB, 1.58 and ∼270 MHz respectively, which agreed well with the simulation results. Furthermore, the results indicate that the design methodology for the radio-frequency textile antenna could have promising applications in flexible and reversibly deformable antennas for wearable wireless communications systems.

  9. Multi-time scaling based modeling of transient electro-magnetic fields in vibrating media with antenna applications

    NASA Astrophysics Data System (ADS)

    Yaghmaie, Reza; Ghosh, Somnath

    2017-07-01

    This paper develops an accurate and efficient finite element model for simulating coupled transient electromagnetic and dynamic mechanical fields that differ widely in the frequency ranges. This coupled modeling framework is necessary for effective modeling and simulation of structures such as antennae that are governed by multi-physics problems operating in different frequency and temporal regimes. A key development is the wavelet transformation induced multi-time scaling or WATMUS method that is designed to overcome shortcomings of modeling coupled multi-physics problems that are governed by disparate frequencies. The WATMUS-based FE model is enhanced in this paper with a scaled and preconditioned Newton-GMRES solver for efficient solution. Results from the WATMUS-based FE model show the accuracy and highly improved computational efficiency in comparison with single time-scale methods. The coupled FE model is used to solve two different antenna problems with large electromagnetic to mechanical frequency ratios. The examples considered are a monopole antenna and a microstrip patch antenna. Comparing the electromagnetic fields with the progression of mechanical cycles demonstrate complex multi-physics relations in these applications.

  10. Multi-time scaling based modeling of transient electro-magnetic fields in vibrating media with antenna applications

    NASA Astrophysics Data System (ADS)

    Yaghmaie, Reza; Ghosh, Somnath

    2017-03-01

    This paper develops an accurate and efficient finite element model for simulating coupled transient electromagnetic and dynamic mechanical fields that differ widely in the frequency ranges. This coupled modeling framework is necessary for effective modeling and simulation of structures such as antennae that are governed by multi-physics problems operating in different frequency and temporal regimes. A key development is the wavelet transformation induced multi-time scaling or WATMUS method that is designed to overcome shortcomings of modeling coupled multi-physics problems that are governed by disparate frequencies. The WATMUS-based FE model is enhanced in this paper with a scaled and preconditioned Newton-GMRES solver for efficient solution. Results from the WATMUS-based FE model show the accuracy and highly improved computational efficiency in comparison with single time-scale methods. The coupled FE model is used to solve two different antenna problems with large electromagnetic to mechanical frequency ratios. The examples considered are a monopole antenna and a microstrip patch antenna. Comparing the electromagnetic fields with the progression of mechanical cycles demonstrate complex multi-physics relations in these applications.

  11. Adaptive optical antennas: design and evaluation

    NASA Astrophysics Data System (ADS)

    Weyrauch, Thomas; Vorontsov, Mikhail A.; Carhart, Gary W.; Simonova, Galina V.; Beresnev, Leonid A.; Polnau, Ernst E.

    2007-09-01

    We present the design and evaluation of compact adaptive optical antennas with apertures diameters of 16 mm and 100 mm for 5Gbit/s-class free-space optical communication systems. The antennas provide a bi-directional optically transparent link between fiber-optical wavelength-division multiplex systems and allow for mitigation of atmospheric-turbulence induced wavefront phase distortions with adaptive optics components. Beam steering is implemented in the antennas either with mirrors on novel tip/tilt platforms or a fiber-tip positioning system, both enabling operation bandwidths of more than 1 kHz. Bimorph piezoelectric actuated deformable mirrors are used for low-order phase-distortion compensation. An imaging system is integrated in the antennas for coarse pointing and tracking. Beam steering and wavefront control is based on blind maximization of the received signal level using a stochastic parallel gradient descent algorithm. The adaptive optics control architecture allowed the use of feedback signals provided locally within each transceiver system and remotely by the opposite transceiver system via an RF link. First atmospheric compensation results from communication experiments over a 250 m near-ground propagation path are presented.

  12. Extensible knowledge-based architecture for segmenting CT data

    NASA Astrophysics Data System (ADS)

    Brown, Matthew S.; McNitt-Gray, Michael F.; Goldin, Jonathan G.; Aberle, Denise R.

    1998-06-01

    A knowledge-based system has been developed for segmenting computed tomography (CT) images. Its modular architecture includes an anatomical model, image processing engine, inference engine and blackboard. The model contains a priori knowledge of size, shape, X-ray attenuation and relative position of anatomical structures. This knowledge is used to constrain low-level segmentation routines. Model-derived constraints and segmented image objects are both transformed into a common feature space and posted on the blackboard. The inference engine then matches image to model objects, based on the constraints. The transformation to feature space allows the knowledge and image data representations to be independent. Thus a high-level model can be used, with data being stored in a frame-based semantic network. This modularity and explicit representation of knowledge allows for straightforward system extension. We initially demonstrate an application to lung segmentation in thoracic CT, with subsequent extension of the knowledge-base to include tumors within the lung fields. The anatomical model was later augmented to include basic brain anatomy including the skull and blood vessels, to allow automatic segmentation of vascular structures in CT angiograms for 3D rendering and visualization.

  13. Statistical analysis of electromagnetic radiation measurements in the vicinity of GSM/UMTS base station antenna masts.

    PubMed

    Koprivica, Mladen; Neskovic, Natasa; Neskovic, Aleksandar; Paunovic, George

    2014-01-01

    As a result of dense installations of public mobile base station, additional electromagnetic radiation occurs in the living environment. In order to determine the level of radio-frequency radiation generated by base stations, extensive electromagnetic field strength measurements were carried out for 664 base station locations. Base station locations were classified into three categories: indoor, masts and locations with installations on buildings. Having in mind the large percentage (47 %) of sites with antenna masts, a detailed analysis of this location category was performed, and the measurement results were presented. It was concluded that the total electric field strength in the vicinity of base station antenna masts in no case exceeded 10 V m(-1), which is quite below the International Commission on Non-Ionizing Radiation Protection reference levels. At horizontal distances >50 m from the mast bottom, the median and maximum values were <1 and 2 V m(-1), respectively.

  14. Smart sensor-based geospatial architecture for dike monitoring

    NASA Astrophysics Data System (ADS)

    Herle, S.; Becker, R.; Blankenbach, J.

    2016-04-01

    Artificial hydraulic structures like dams or dikes used for water level regulations or flood prevention are continuously under the influence of the weather and variable river regimes. Thus, ongoing monitoring and simulation is crucial in order to determine the inner condition. Potentially life-threatening situations, in extreme case a failure, must be counteracted by all available means. Nowadays flood warning systems rely exclusively on water level forecast without considering the state of the structure itself. Area-covering continuous knowledge of the inner state including time dependent changes increases the capability of recognizing and locating vulnerable spots for early treatment. In case of a predicted breach, advance warning time for alerting affected citizens can be extended. Our approach is composed of smart sensors integrated in a service-oriented geospatial architecture to monitor and simulate artificial hydraulic structures continuously. The sensors observe the inner state of the construction like the soil moisture or the stress and deformation over time but also various external influences like water levels or wind speed. They are interconnected in distributed network architecture by a so-called sensor bus system based on lightweight protocols like Message Queue Telemetry Transport for Sensor Networks (MQTT-SN). These sensor data streams are transferred into an OGC Sensor Web Enablement (SWE) data structure providing high-level geo web services to end users. Bundled with 3rd party geo web services (WMS etc.) powerful processing and simulation tools can be invoked using the Web Processing Service (WPS) standard. Results will be visualized in a geoportal allowing user access to all information.

  15. Practical Sub-Nyquist Sampling via Array-Based Compressed Sensing Receiver Architecture

    DTIC Science & Technology

    2016-07-10

    Practical Sub-Nyquist Sampling via Array-based Compressed Sensing Receiver Architecture Andrew K. Bolstad∗, James Edwin Vian∗, Jonathan D. Chisum... Architecture (ACRA). ACRA allows digital receiver arrays to operate at dramatically larger instantaneous bandwidths by sampling the signals from...alogirhtm keeps track of the σl and τl used in each location loop. III. ARRAY-BASED COMPRESSED SENSING RECEIVER ARCHITECTURE Consider a typical digital

  16. Development of a Gimballed, dual frequency, space-based, microwave antenna for volume production

    NASA Technical Reports Server (NTRS)

    Leckie, Martin; Laidig, Dave

    1996-01-01

    A dual-frequency, two-axis Gimballed, Microwave Antenna (GMA) has been developed by COM DEV and Motorola for commercial satellites. The need for volume production of over three hundred antennas at a rate of four per week, a compressed development schedule, and the commercial nature of the effort necessitated a paradigm shift to an 'overall' cost-driven design approach. The translation of these demands into antenna requirements, a description of the resulting GMA design, and examples of development issues are detailed herein.

  17. Microwave sensor for tangerine classification based on coupled-patch antennas

    NASA Astrophysics Data System (ADS)

    Leekul, Prapan; Chivapreecha, Sorawat; Krairiksh, Monai

    2016-08-01

    This paper deals with a microwave sensor for classifying tangerines by flavour using coupled-patch antennas. The operating frequency of the antennas is 2.45 GHz. The sensor determines the flavour of each tangerine by measuring the magnitudes of coupled signals of the antennas with the tangerine fruit at the centre. The sorting is carried out using an artificial neural network implemented on a field programmable gate array. The classification performance of the sensor is 95% accurate, so it has potential for use in sorting tangerines by flavour. In addition, the system uncertainty is analysed to determine optimal operating conditions.

  18. RAINBOW: Architecture-Based Adaptation of Complex Systems

    DTIC Science & Technology

    2005-04-01

    2 This is the core architectural representation scheme adopted by a number of ADLs, including Acme [8], xArch [3], xADL [5], ADML [15], and SADL...International, Mar. 1997. 15. The OpenGroup. Architecture Description Markup Language ( ADML ) Version 1. Apr. 2000. Available at http

  19. Water System Architectures for Moon and Mars Bases

    NASA Technical Reports Server (NTRS)

    Jones, Harry W.; Hodgson, Edward W.; Kliss, Mark H.

    2015-01-01

    Water systems for human bases on the moon and Mars will recycle multiple sources of wastewater. Systems for both the moon and Mars will also store water to support and backup the recycling system. Most water system requirements, such as number of crew, quantity and quality of water supply, presence of gravity, and surface mission duration of 6 or 18 months, will be similar for the moon and Mars. If the water system fails, a crew on the moon can quickly receive spare parts and supplies or return to Earth, but a crew on Mars cannot. A recycling system on the moon can have a reasonable reliability goal, such as only one unrecoverable failure every five years, if there is enough stored water to allow time for attempted repairs and for the crew to return if repair fails. The water system that has been developed and successfully operated on the International Space Station (ISS) could be used on a moon base. To achieve the same high level of crew safety on Mars without an escape option, either the recycling system must have much higher reliability or enough water must be stored to allow the crew to survive the full duration of the Mars surface mission. A three loop water system architecture that separately recycles condensate, wash water, and urine and flush can improve reliability and reduce cost for a Mars base.

  20. Soft-core processor study for node-based architectures.

    SciTech Connect

    Van Houten, Jonathan Roger; Jarosz, Jason P.; Welch, Benjamin James; Gallegos, Daniel E.; Learn, Mark Walter

    2008-09-01

    Node-based architecture (NBA) designs for future satellite projects hold the promise of decreasing system development time and costs, size, weight, and power and positioning the laboratory to address other emerging mission opportunities quickly. Reconfigurable Field Programmable Gate Array (FPGA) based modules will comprise the core of several of the NBA nodes. Microprocessing capabilities will be necessary with varying degrees of mission-specific performance requirements on these nodes. To enable the flexibility of these reconfigurable nodes, it is advantageous to incorporate the microprocessor into the FPGA itself, either as a hardcore processor built into the FPGA or as a soft-core processor built out of FPGA elements. This document describes the evaluation of three reconfigurable FPGA based processors for use in future NBA systems--two soft cores (MicroBlaze and non-fault-tolerant LEON) and one hard core (PowerPC 405). Two standard performance benchmark applications were developed for each processor. The first, Dhrystone, is a fixed-point operation metric. The second, Whetstone, is a floating-point operation metric. Several trials were run at varying code locations, loop counts, processor speeds, and cache configurations. FPGA resource utilization was recorded for each configuration. Cache configurations impacted the results greatly; for optimal processor efficiency it is necessary to enable caches on the processors. Processor caches carry a penalty; cache error mitigation is necessary when operating in a radiation environment.

  1. The simcyp population based simulator: architecture, implementation, and quality assurance.

    PubMed

    Jamei, Masoud; Marciniak, Steve; Edwards, Duncan; Wragg, Kris; Feng, Kairui; Barnett, Adrian; Rostami-Hodjegan, Amin

    2013-01-01

    Developing a user-friendly platform that can handle a vast number of complex physiologically based pharmacokinetic and pharmacodynamic (PBPK/PD) models both for conventional small molecules and larger biologic drugs is a substantial challenge. Over the last decade the Simcyp Population Based Simulator has gained popularity in major pharmaceutical companies (70% of top 40 - in term of R&D spending). Under the Simcyp Consortium guidance, it has evolved from a simple drug-drug interaction tool to a sophisticated and comprehensive Model Based Drug Development (MBDD) platform that covers a broad range of applications spanning from early drug discovery to late drug development. This article provides an update on the latest architectural and implementation developments within the Simulator. Interconnection between peripheral modules, the dynamic model building process and compound and population data handling are all described. The Simcyp Data Management (SDM) system, which contains the system and drug databases, can help with implementing quality standards by seamless integration and tracking of any changes. This also helps with internal approval procedures, validation and auto-testing of the new implemented models and algorithms, an area of high interest to regulatory bodies.

  2. SPS antenna pointing control

    NASA Technical Reports Server (NTRS)

    Hung, J. C.

    1980-01-01

    The pointing control of a microwave antenna of the Satellite Power System was investigated emphasizing: (1) the SPS antenna pointing error sensing method; (2) a rigid body pointing control design; and (3) approaches for modeling the flexible body characteristics of the solar collector. Accuracy requirements for the antenna pointing control consist of a mechanical pointing control accuracy of three arc-minutes and an electronic phased array pointing accuracy of three arc-seconds. Results based on the factors considered in current analysis, show that the three arc-minute overall pointing control accuracy can be achieved in practice.

  3. Satellite Antenna Systems

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Through the Technology Affiliates Program at the Jet Propulsion Laboratory, the ACTS antenna system was transferred from experimental testing status to commercial development with KVH Industries, Inc. The ACTS design enables mobile satellite antennas to remain pointed at the satellite, regardless of the motion or vibration on which it is mounted. KVH's first product based on the ACTS design is a land-mobile satellite antenna system that will enable direct broadcast satellite television aboard moving trucks, recreational vehicles, trains, and buses. Future products could include use in broadcasting, emergency medical and military vehicles.

  4. An Efficient, Wideband, CPW-Fed Antenna Based on Simplified Composite Right/Left-Handed Transmission Line

    NASA Astrophysics Data System (ADS)

    Li, Zhaozhan; Zhou, Cheng; Lin, Yanhong

    2017-01-01

    A wideband electrically small antenna (ESA) based on simplified composite right/left-handed transmission line (SCRLH-TL) is designed, fabricated and tested. The antenna consists of two different sized SCRLH-TL unit cells with different+1st-order mode resonance frequencies. The wideband property of antenna is achieved when these two+1st-order mode resonance frequency suitably merge. A dispersion analysis of the SCRLH-TL reveals that an increase in series of the dual-spiral capacitor would decrease the+1st-order mode resonance frequency, thus reducing the electrical size of the proposed antenna. The 10 dB fractional bandwidth (FBW10 dB) was 54.5 % and the measured maximum was 96.2 %, with an electrical size of 0.32λ0×0.16λ0×0.015λ0 at 3.0 GHz (where λ0 is the wavelength in vacuum). It is shown that the numerical results closely fit the measured results.

  5. Specific absorption rate and electric field measurements in the near field of six mobile phone base station antennas.

    PubMed

    Toivonen, Tommi; Toivo, Tim; Puranen, Lauri; Jokela, Kari

    2009-05-01

    In this article, the exposure to radio frequency electromagnetic fields was studied in close proximity (distances of 10, 100, 300, and 600 mm) to six base station antennas. The specific absorption rate (SAR) in 800 mm x 500 mm x 200 mm box phantom as well as unperturbed electric field (E) in air was measured. The results were used to determine whether the measurement of local maximum of unperturbed electric field can be used as a compliance check for local exposure. Also, the conservativeness of this assessment method compared to the ICNIRP basic restriction was studied. Moreover, the assessment of whole-body exposure was discussed and the distance ranges presented in which the ICNIRP limit for local exposure could be exceeded before the limit for whole-body SAR. These results show that the electric field measurement alone can be used for easy compliance check for the local exposure at all distances and for all antenna types studied. However, in some cases when the local peak value of E was compared directly to the ICNIRP reference level for unperturbed E, the exposure was overestimated only very slightly (by factor 1.1) compared to the basic restriction for localized SAR in a human, and hence these results can not be generalized to all antenna types. Moreover, it was shown that the limit for localized exposure could be exceeded before the limit for the whole-body average SAR, if the distance to the antenna was less than 240 mm.

  6. An arc control and protection system for the JET lower hybrid antenna based on an imaging system

    SciTech Connect

    Figueiredo, J.

    2014-11-15

    Arcs are the potentially most dangerous events related to Lower Hybrid (LH) antenna operation. If left uncontrolled they can produce damage and cause plasma disruption by impurity influx. To address this issue an arc real time control and protection imaging system for the Joint European Torus (JET) LH antenna has been implemented. The LH system is one of the additional heating systems at JET. It comprises 24 microwave generators (klystrons, operating at 3.7 GHz) providing up to 5 MW of heating and current drive to the JET plasma. This is done through an antenna composed of an array of waveguides facing the plasma. The protection system presented here is based primarily on an imaging arc detection and real time control system. It has adapted the ITER like wall hotspot protection system using an identical CCD camera and real time image processing unit. A filter has been installed to avoid saturation and spurious system triggers caused by ionization light. The antenna is divided in 24 Regions Of Interest (ROIs) each one corresponding to one klystron. If an arc precursor is detected in a ROI, power is reduced locally with subsequent potential damage and plasma disruption avoided. The power is subsequently reinstated if, during a defined interval of time, arcing is confirmed not to be present by image analysis. This system was successfully commissioned during the restart phase and beginning of the 2013 scientific campaign. Since its installation and commissioning, arcs and related phenomena have been prevented. In this contribution we briefly describe the camera, image processing, and real time control systems. Most importantly, we demonstrate that an LH antenna arc protection system based on CCD camera imaging systems works. Examples of both controlled and uncontrolled LH arc events and their consequences are shown.

  7. An arc control and protection system for the JET lower hybrid antenna based on an imaging system

    NASA Astrophysics Data System (ADS)

    Figueiredo, J.; Mailloux, J.; Kirov, K.; Kinna, D.; Stamp, M.; Devaux, S.; Arnoux, G.; Edwards, J. S.; Stephen, A. V.; McCullen, P.; Hogben, C.

    2014-11-01

    Arcs are the potentially most dangerous events related to Lower Hybrid (LH) antenna operation. If left uncontrolled they can produce damage and cause plasma disruption by impurity influx. To address this issue an arc real time control and protection imaging system for the Joint European Torus (JET) LH antenna has been implemented. The LH system is one of the additional heating systems at JET. It comprises 24 microwave generators (klystrons, operating at 3.7 GHz) providing up to 5 MW of heating and current drive to the JET plasma. This is done through an antenna composed of an array of waveguides facing the plasma. The protection system presented here is based primarily on an imaging arc detection and real time control system. It has adapted the ITER like wall hotspot protection system using an identical CCD camera and real time image processing unit. A filter has been installed to avoid saturation and spurious system triggers caused by ionization light. The antenna is divided in 24 Regions Of Interest (ROIs) each one corresponding to one klystron. If an arc precursor is detected in a ROI, power is reduced locally with subsequent potential damage and plasma disruption avoided. The power is subsequently reinstated if, during a defined interval of time, arcing is confirmed not to be present by image analysis. This system was successfully commissioned during the restart phase and beginning of the 2013 scientific campaign. Since its installation and commissioning, arcs and related phenomena have been prevented. In this contribution we briefly describe the camera, image processing, and real time control systems. Most importantly, we demonstrate that an LH antenna arc protection system based on CCD camera imaging systems works. Examples of both controlled and uncontrolled LH arc events and their consequences are shown.

  8. An arc control and protection system for the JET lower hybrid antenna based on an imaging system.

    PubMed

    Figueiredo, J; Mailloux, J; Kirov, K; Kinna, D; Stamp, M; Devaux, S; Arnoux, G; Edwards, J S; Stephen, A V; McCullen, P; Hogben, C

    2014-11-01

    Arcs are the potentially most dangerous events related to Lower Hybrid (LH) antenna operation. If left uncontrolled they can produce damage and cause plasma disruption by impurity influx. To address this issue an arc real time control and protection imaging system for the Joint European Torus (JET) LH antenna has been implemented. The LH system is one of the additional heating systems at JET. It comprises 24 microwave generators (klystrons, operating at 3.7 GHz) providing up to 5 MW of heating and current drive to the JET plasma. This is done through an antenna composed of an array of waveguides facing the plasma. The protection system presented here is based primarily on an imaging arc detection and real time control system. It has adapted the ITER like wall hotspot protection system using an identical CCD camera and real time image processing unit. A filter has been installed to avoid saturation and spurious system triggers caused by ionization light. The antenna is divided in 24 Regions Of Interest (ROIs) each one corresponding to one klystron. If an arc precursor is detected in a ROI, power is reduced locally with subsequent potential damage and plasma disruption avoided. The power is subsequently reinstated if, during a defined interval of time, arcing is confirmed not to be present by image analysis. This system was successfully commissioned during the restart phase and beginning of the 2013 scientific campaign. Since its installation and commissioning, arcs and related phenomena have been prevented. In this contribution we briefly describe the camera, image processing, and real time control systems. Most importantly, we demonstrate that an LH antenna arc protection system based on CCD camera imaging systems works. Examples of both controlled and uncontrolled LH arc events and their consequences are shown.

  9. Towards efficient and tunable generation of THz radiation from quantum dot based ultrafast photoconductive antennae (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Gorodetsky, Andrei; Fedorova, Ksenia A.; Bazieva, Natalia; Rafailov, Edik U.

    2016-10-01

    We present our recent results on CW and pulsed THz generation in quantum dot(QD) based photoconductive antennae(PCA) pumped by ultrafast and dual wavelength semiconductor lasers. QDPCA substrate incorporates InAs QDs in GaAs matrix, thus keeping semiconductor carrier mobility at higher levels that is typical for SI GaAs, while QDs themselves serve as lifetime shortening centres, allowing to achieve subpicosecond operation as in LT-GaAs. Thus, such substrates combine the advantages and lacking the disadvantages of GaAs and LT-GaAs, which are the most popular materials so far, and thus can be used for both CW and pulsed THz generation. Moreover, by changing QD size and mutual allocation, effective pump wavelengths can be tuned in the range between 0.9-1.3 μm, which is well beyond the GaAs energies, hence compact and relatively cheap ultrafast and narrow line double-wavelength semiconductor and fibre pump lasers can be used for pumping such antennae for both pulsed and CW THz generation. For double wavelength operation of semiconductor lasers, we implement either stacked double volume Bragg gratings, or double-Littrow configuration with two independent diffraction gratings to achieve tunability of the generated THz signal. High thermal tolerance of QD wafers allowed pumping single-gapped antennae with lasers producing up to 250 mW of CW optical power at simultaneous double wavelength operation and up to 1W average optical power in pulsed regime. We show these QD based antennae combined with such pump lasers to generate pulsed and CW THz radiation that is superlinearly proportional to pump power and bias applied to antenna.

  10. Juno Microwave Radiometer Patch Array Antennas

    NASA Technical Reports Server (NTRS)

    Chamberlain, N.; Chen, J.; Focardi, P.; Hodges, R.; Hughes, R.; Jakoboski, J.; Venkatesan, J.; Zawadzki, M.

    2009-01-01

    Juno is a mission in the NASA New Frontiers Program with the goal of significantly improving our understanding of the formation and structure of Jupiter. This paper discusses the modeling and measurement of the two patch array antennas. An overview of the antenna architecture, design and development at JPL is provided, along with estimates of performance and the results of measurements.

  11. Efficient Placement of Directional Antennas

    SciTech Connect

    Pan, Feng; Kasiviswanathan, Shiva

    2010-09-20

    Directional antenna is an technology for the proliferation of wireless networks. In centralized wireless network, wireless devices communicate through base stations. Directed antennas are placed on base stations and form a backbone of communication. The communication between base stations and wireless devices can be interfered due to a large number of wireless device. Methodically positioning and orienting directed antennas can help to reduce the interference while saving energy. An integer linear programming is developed for siting and directing antennas on multiple base stations, and this formulation can be extended to model non-overlapping channels. Through the integer programming formulation, optimal antenna positions can be used to analyze the performance of directed antennas with different parameters like the number base stations and the number of non-overlapping channels.

  12. Location Dependency and Antenna/Body/Sensor-Lead Interaction Effects in a Cell-Phone Based GSM 1800 Telemedicine Link

    DTIC Science & Technology

    2001-10-25

    Abstract-The error-free requirement of today’s cell - phone based telemedicine systems demands investigations into the potential causes of service...a building, compared to that found in the U.K. Macro effects. Representative temporal variation measurements (made with a calibrated cell - phone ...reduction of 10 dB, outer-to-inner. Location Dependency and Antenna / Body / Sensor-lead Interaction Effects in a Cell - phone Based GSM 1800 Telemedicine

  13. Antipodal Linear Tapered Slot Antenna Based Radio Link Characterization in Narrow Hallway Environment at 60 GHz

    NASA Astrophysics Data System (ADS)

    Shrivastava, Purva; Rao, T. Rama

    2016-09-01

    The performance of wireless communication systems is predominantly dependent on propagation environment and respective radiating antennas. Due to the shorter wavelength at millimeter wave (MmW) frequencies, the propagation loss through the objects in indoor environments is typically very high. To improve the channel capacity and to reduce inter-user interference, a high gain directional antenna is desired at MmW frequencies. Traditional antennas used in MmW devices are not suitable for low-cost commercial devices due to their heavy and bulky configurations. This paper focuses on design and development of a very compact (44.61 × 9.93 × 0.381 mm) high gain antipodal linear tapered slot antenna (ALTSA) utilizing substrate integrated waveguide (SIW) technology at 60 GHz. Received signal strength (RSS), path loss, and capacity are studied for MmW indoor applications utilizing ALTSA with radio frequency (RF) measurement equipment in narrow hallway environment.

  14. Antennas for the array-based Deep Space Network: current status and future designs

    NASA Technical Reports Server (NTRS)

    Imbriale, William A.; Gama, Eric

    2005-01-01

    Development of very large arrays1,2 of small antennas has been proposed as a way to increase the downlink capability of the NASA Deep Space Network DSN) by two or three orders of magnitude thereby enabling greatly increased science data from currently configured missions or enabling new mission concepts. The current concept is for an array of 400 x 12-m antennas at each of three longitudes. The DSN array will utilize radio astronomy sources for phase calibration and will have wide bandwidth correlation processing for this purpose. NASA has undertaken a technology program to prove the performance and cost of a very large DSN array. Central to that program is a 3-element interferometer to be completed in 2005. This paper describes current status of the low cost 6-meter breadboard antenna to be used as part of the interferometer and the RF design of the 12-meter antenna.

  15. Moon-Based Advanced Reusable Transportation Architecture: The MARTA Project

    NASA Astrophysics Data System (ADS)

    Alexander, R.; Bechtel, R.; Chen, T.; Cormier, T.; Kalaver, S.; Kirtas, M.; Lewe, J.-H.; Marcus, L.; Marshall, D.; Medlin, M.; McIntire, J.; Nelson, D.; Remolina, D.; Scott, A.; Weglian, J.; Olds, J.

    2000-01-01

    The Moon-based Advanced Reusable Transportation Architecture (MARTA) Project conducted an in-depth investigation of possible Low Earth Orbit (LEO) to lunar surface transportation systems capable of sending both astronauts and large masses of cargo to the Moon and back. This investigation was conducted from the perspective of a private company operating the transportation system for a profit. The goal of this company was to provide an Internal Rate of Return (IRR) of 25% to its shareholders. The technical aspect of the study began with a wide open design space that included nuclear rockets and tether systems as possible propulsion systems. Based on technical, political, and business considerations, the architecture was quickly narrowed down to a traditional chemical rocket using liquid oxygen and liquid hydrogen. However, three additional technologies were identified for further investigation: aerobraking, in-situ resource utilization (ISRU), and a mass driver on the lunar surface. These three technologies were identified because they reduce the mass of propellant used. Operational costs are the largest expense with propellant cost the largest contributor. ISRU, the production of materials using resources on the Moon, was considered because an Earth to Orbit (ETO) launch cost of 1600 per kilogram made taking propellant from the Earth's surface an expensive proposition. The use of an aerobrake to circularize the orbit of a vehicle coming from the Moon towards Earth eliminated 3, 100 meters per second of velocity change (Delta V), eliminating almost 30% of the 11,200 m/s required for one complete round trip. The use of a mass driver on the lunar surface, in conjunction with an ISRU production facility, would reduce the amount of propellant required by eliminating using propellant to take additional propellant from the lunar surface to Low Lunar Orbit (LLO). However, developing and operating such a system required further study to identify if it was cost effective. The

  16. Active antenna

    NASA Technical Reports Server (NTRS)

    Sutton, John F. (Inventor)

    1994-01-01

    An antenna, which may be a search coil, is connected to an operational amplifier circuit which provides negative impedances, each of which is in the order of magnitude of the positive impedances which characterize the antenna. The antenna is connected to the inverting input of the operational amplifier; a resistor is connected between the inverting input and the output of the operational amplifier; a capacitor-resistor network, in parallel, is connected between the output and the noninverting input of the operational amplifier; and a resistor is connected from the noninverting input and the circuit common. While this circuit provides a negative resistance and a negative inductance, in series, which appear, looking into the noninverting input of the operational amplifier, in parallel with the antenna, these negative impedances appear in a series loop with the antenna positive impedances, so as to algebraically add. This circuit is tuned by varying the various circuit components so that the negative impedances are very close, but somewhat less, in magnitude, to the antenna impedances. The result is to increase the sensitivity of the antenna by lowering its effective impedance. This, in turn, increases the effective area of the antenna, which may be broadband.

  17. A generalized locomotion CPG architecture based on oscillatory building blocks.

    PubMed

    Yang, Zhijun; França, Felipe M G

    2003-07-01

    Neural oscillation is one of the most extensively investigated topics of artificial neural networks. Scientific approaches to the functionalities of both natural and artificial intelligences are strongly related to mechanisms underlying oscillatory activities. This paper concerns itself with the assumption of the existence of central pattern generators (CPGs), which are the plausible neural architectures with oscillatory capabilities, and presents a discrete and generalized approach to the functionality of locomotor CPGs of legged animals. Based on scheduling by multiple edge reversal (SMER), a primitive and deterministic distributed algorithm, it is shown how oscillatory building block (OBB) modules can be created and, hence, how OBB-based networks can be formulated as asymmetric Hopfield-like neural networks for the generation of complex coordinated rhythmic patterns observed among pairs of biological motor neurons working during different gait patterns. It is also shown that the resulting Hopfield-like network possesses the property of reproducing the whole spectrum of different gaits intrinsic to the target locomotor CPGs. Although the new approach is not restricted to the understanding of the neurolocomotor system of any particular animal, hexapodal and quadrupedal gait patterns are chosen as illustrations given the wide interest expressed by the ongoing research in the area.

  18. Digitally Driven Antenna for HF Transmission

    DTIC Science & Technology

    2010-09-01

    and reception and the fast Fourier transform (FFT). From Ampere’s Law, (2) it is seen that the magnetic field is proportional to the current density... pulse train. This is defined here as the digitally driven antenna architecture. A circuit simulator with broadband equivalent-circuit models for the...HF signal from the digital pulse train. This is defined here as the digitally driven antenna architecture. A circuit simulator with broadband

  19. Design of a composite right/left-handed transmission line unit-cell for a U-shaped mushroom ZOR antenna based on left-handed metamaterials

    NASA Astrophysics Data System (ADS)

    Lee, Cherl-Hee; Lee, Jonghun; Woo, Dong-Sik; Kim, Kang-Wook

    2012-11-01

    In this paper, a metamaterial-based zeroth-order (ZOR) mushroom antenna is presented by using a new composite right/left-handed (CRLH) transmission line unit-cell implemented with a U-shaped top plate is presented to extend bandwidth. The ZOR antenna whose resonance frequency is independent of the antenna size can enable a reduction of the antenna size. Because the shunt capacitance is determined by the area of a mushroom patch, a U-shaped mushroom having a lower shunt capacitance than the Sievenpiper mushroom structure is properly designed to widen the small bandwidth of the CRLH TL antenna. Compared to a square-shaped mushroom structure, a U-shaped mushroom structure for three unit-cells provided a reduced shunt capacitance and increased the 10-dB bandwidth by 2.5 times at 9.37 GHz.

  20. Reliability-centered maintenance for ground-based large optical telescopes and radio antenna arrays

    NASA Astrophysics Data System (ADS)

    Marchiori, G.; Formentin, F.; Rampini, F.

    2014-07-01

    In the last years, EIE GROUP has been more and more involved in large optical telescopes and radio antennas array projects. In this frame, the paper describes a fundamental aspect of the Logistic Support Analysis (LSA) process, that is the application of the Reliability-Centered Maintenance (RCM) methodology for the generation of maintenance plans for ground-based large optical telescopes and radio antennas arrays. This helps maintenance engineers to make sure that the telescopes continue to work properly, doing what their users require them to do in their present operating conditions. The main objective of the RCM process is to establish the complete maintenance regime, with the safe minimum required maintenance, carried out without any risk to personnel, telescope and subsystems. At the same time, a correct application of the RCM allows to increase the cost effectiveness, telescope uptime and items availability, and to provide greater understanding of the level of risk that the organization is managing. At the same time, engineers shall make a great effort since the initial phase of the project to obtain a telescope requiring easy maintenance activities and simple replacement of the major assemblies, taking special care on the accesses design and items location, implementation and design of special lifting equipment and handling devices for the heavy items. This maintenance engineering framework is based on seven points, which lead to the main steps of the RCM program. The initial steps of the RCM process consist of: system selection and data collection (MTBF, MTTR, etc.), definition of system boundaries and operating context, telescope description with the use of functional block diagrams, and the running of a FMECA to address the dominant causes of equipment failure and to lay down the Critical Items List. In the second part of the process the RCM logic is applied, which helps to determine the appropriate maintenance tasks for each identified failure mode. Once

  1. Maximizing Channel Capacity based on Antenna and MIMO Channel Characteristics and its Application to Multimedia Data Transmission

    NASA Astrophysics Data System (ADS)

    Pottkotter, Andrew

    Communication transmission between electronic devices is evolving at an ever faster pace. There are now more electronic handheld devices that we communicate with on a daily basis. The allotted bandwidth and speed for these devices are limited by hardware, software, handshaking capabilities between each electronic application. The demand for information at high data rates without the loss of reliability has evolved antenna technology and digital signal processing into more complex systems utilizing multiple processors and multiple antennas. This paper discusses the various techniques used to increase data speed, enhance channel capacity, and reliability of application specific devices with respect to the Multiple-Input-to-Multiple-Output (MIMO) based methods. MIMO based applications can improve the data speed, channel capacity, and reliability of the system with maximum limitations based on hardware, coding schemes, and handshaking abilities between devices.

  2. Field enhancement with plasmonic nano-antennas on silicon-based waveguides

    NASA Astrophysics Data System (ADS)

    Darvishzadeh-Varcheie, M.; Guclu, C.; Ragan, R.; Boyraz, O.; Capolino, F.

    2015-09-01

    Plasmonic nano antennas like dimers, have been investigated for their capability to provide a strong near-field enhancement when illuminated by external light. Traditionally these nano antennas, isolated or arrayed, are placed on a substrate and used in spectroscopy techniques. Surfaces made of such plasmonic nano antennas have been very useful for applications like surface enhanced Raman scattering in which it provides various orders of magnitude of enhanced sensitivity. These instruments however are not economic and are often not mobile since surfaces require an external beam illumination and the Raman scattering is detected by a large aperture microscope. The goal of this paper is to combine nano antennas made of gold dimers with integrated waveguide to make a spectrometer which has low cost and volume in comparison with the structure mentioned above. A technique in which optical plasmonic nano antennas are located in proximity of silicon nitride waveguide is proposed that is useful both for illumination and detection channels. The waveguide evanescent field, which is decaying outside of the waveguide, excites the dimer and causes it to resonate which results in a very strong electric field enhancement of approximately 25 times in the antenna gap. Also the coupling effect of dimer resonance on waveguide modes is investigated. To show the efficiency of the proposed structure, full wave analysis has been done and its results are compared with the multilayer structure case. The simulation results demonstrate that this structure can be designed and fabricated for the purpose of spectroscopy application.

  3. Investigation of a Biocompatible Polyurethane-Based Isotropically Conductive Adhesive for UHF RFID Tag Antennas

    NASA Astrophysics Data System (ADS)

    Yang, Cheng; Yuen, Matthew M. F.; Gao, Bo; Ma, Yuhui; Wong, C. P.

    2011-01-01

    As a candidate dispersant for silver-based isotropically conductive adhesives (ICAs), polyurethane (PU) is an environmentally benign material that can withstand a high deformation rate and that exhibits excellent reliability. In this work we investigated methyl ethyl ketoxime (MEKO) blocked isophorone diisocyanate (IPDI) and MEKO blocked hexamethylene diisocyanate (HDI) as dispersant materials, and we characterize the electrical conductivity, mechanical properties, and reliability of these PU-based ICAs with silver-flake filler content ranging from 30 wt.% to 75 wt.%. Results of temperature-humidity testing (THT) at 85°C and 85% relative humidity (RH) and thermal cycling testing (TCT) at -40°C to 125°C show that these ICAs have excellent reliability. Our experimental results suggest that the MEKO blocked PU dispersants are suitable for preparing ultralow-cost, flexible, high-performance ICAs for printing antennas for ultrahigh-frequency radiofrequency identification (RFID) tags. These tags can potentially be used for identifying washable items and food packaging.

  4. Actuation mechanisms of carbon nanotube-based architectures

    NASA Astrophysics Data System (ADS)

    Geier, Sebastian; Mahrholz, Thorsten; Wierach, Peter; Sinapius, Michael

    2016-04-01

    State of the art smart materials such as piezo ceramics or electroactive polymers cannot feature both, mechanical stiffness and high active strain. Moreover, properties like low density, high mechanical stiffness and high strain at the same time driven by low energy play an increasingly important role for their future application. Carbon nanotubes (CNT), show this behavior. Their active behavior was observed 1999 the first time using paper-like mats made of CNT. Therefore the CNT-papers are electrical charged within an electrolyte thus forming a double- layer. The measured deflection of CNT material is based on the interaction between the charged high surface area formed by carbon nanotubes and ions provided by the electrolyte. Although CNT-papers have been extensively analyzed as well at the macro-scale as nano-scale there is still no generally accepted theory for the actuation mechanism. This paper focuses on investigations of the actuation mechanisms of CNT-papers in comparison to vertically aligned CNT-arrays. One reason of divergent results found in literature might be attributed to different types of CNT samples. While CNT-papers represent architectures of short CNTs which need to bridge each other to form the dimensions of the sample, the continuous CNTs of the array feature a length of almost 3 mm, along which the experiments are carried out. Both sample types are tested within an actuated tensile test set-up under different conditions. While the CNT-papers are tested in water-based electrolytes with comparably small redox-windows the hydrophobic CNT-arrays are tested in ionic liquids with comparatively larger redox-ranges. Furthermore an in-situ micro tensile test within an SEM is carried out to prove the optimized orientation of the MWCNTs as result of external load. It was found that the performance of CNT-papers strongly depends on the test conditions. However, the CNT-arrays are almost unaffected by the conditions showing active response at negative

  5. Photonic true-time-delays based on multiplexed substrate-guided wave propagation for phased array antenna applications

    NASA Astrophysics Data System (ADS)

    Chen, Ray T.; Li, Richard L.

    1996-11-01

    A compact and affordable photonic true-time-delay (TTD) beam steering device for phased array antenna applications using multiplexed substrate-guided wave propagation is presented. The TTD design uses holographic input and output couplers to change the direction of beam propagation as well as optical fanout. Optical delays of various delay lines can be adjusted easily through the substrate thickness and the total internal reflection angle inside the substrate material. Broadband microwave signals for feeding the radiating elements are generated through optical heterodyne technique and they are detected by metal-semiconductor-metal detector arrays. The physical aspects of phase-shifters and true-time-delays are first introduced. Then design issues on the photonic TTD architecture and practical constraints on making holographic grating couplers are discussed, especially concerning with recording gratings on DuPont photopolymer materials. Finally, the generation and detection of high frequency microwave signals up to 25 GHz by optical heterodyne techniques are illustrated.

  6. Bidirectional MIMO and SISO 3GPP LTE-advanced fronthaul architectures based on multicore fiber

    NASA Astrophysics Data System (ADS)

    Llorente, Roberto; Morant, Maria

    2017-01-01

    Multicore fiber (MCF) systems have been proposed for high capacity optical transmission applications ranging from the access network to long haul. In this paper we critically review the application of MCF-based systems in optical fronthaul technology with the simultaneous radio-over-fiber (RoF) transmission of 3GPP LTE-Advanced signals in downlink and uplink directions. The experimental study evaluates the quality of the received signals in terms of error vector magnitude (EVM) of the LTE-Advanced signal and of each channel frame according to the 3GPP wireless standard. The suitability of the 3GPP MIMO processing algorithms is also investigated experimentally evaluating two-antenna and four-antenna system configuration and compared with single-antenna (SISO) transmission in a 4-core MCF.

  7. An event-based architecture for solving constraint satisfaction problems.

    PubMed

    Mostafa, Hesham; Müller, Lorenz K; Indiveri, Giacomo

    2015-12-08

    Constraint satisfaction problems are ubiquitous in many domains. They are typically solved using conventional digital computing architectures that do not reflect the distributed nature of many of these problems, and are thus ill-suited for solving them. Here we present a parallel analogue/digital hardware architecture specifically designed to solve such problems. We cast constraint satisfaction problems as networks of stereotyped nodes that communicate using digital pulses, or events. Each node contains an oscillator implemented using analogue circuits. The non-repeating phase relations among the oscillators drive the exploration of the solution space. We show that this hardware architecture can yield state-of-the-art performance on random SAT problems under reasonable assumptions on the implementation. We present measurements from a prototype electronic chip to demonstrate that a physical implementation of the proposed architecture is robust to practical non-idealities and to validate the theory proposed.

  8. An event-based architecture for solving constraint satisfaction problems

    PubMed Central

    Mostafa, Hesham; Müller, Lorenz K.; Indiveri, Giacomo

    2015-01-01

    Constraint satisfaction problems are ubiquitous in many domains. They are typically solved using conventional digital computing architectures that do not reflect the distributed nature of many of these problems, and are thus ill-suited for solving them. Here we present a parallel analogue/digital hardware architecture specifically designed to solve such problems. We cast constraint satisfaction problems as networks of stereotyped nodes that communicate using digital pulses, or events. Each node contains an oscillator implemented using analogue circuits. The non-repeating phase relations among the oscillators drive the exploration of the solution space. We show that this hardware architecture can yield state-of-the-art performance on random SAT problems under reasonable assumptions on the implementation. We present measurements from a prototype electronic chip to demonstrate that a physical implementation of the proposed architecture is robust to practical non-idealities and to validate the theory proposed. PMID:26642827

  9. Advantages of a Geographically Diverse Ground Based Architecture for SSA

    NASA Astrophysics Data System (ADS)

    Houlton, B.; Hall, B.

    By employing a distributed optical ground architecture, AGI has demonstrated the ability to refine the orbital uncertainty for geostationary satellites. This refinement significantly enhances the ability to maintain custody and characterize the behavior and attributes of GEO satellites.

  10. A Simple Physical Optics Algorithm Perfect for Parallel Computing Architecture

    NASA Technical Reports Server (NTRS)

    Imbriale, W. A.; Cwik, T.

    1994-01-01

    A reflector antenna computer program based upon a simple discreet approximation of the radiation integral has proven to be extremely easy to adapt to the parallel computing architecture of the modest number of large-gain computing elements such as are used in the Intel iPSC and Touchstone Delta parallel machines.

  11. A Simple Physical Optics Algorithm Perfect for Parallel Computing Architecture

    NASA Technical Reports Server (NTRS)

    Imbriale, W. A.; Cwik, T.

    1994-01-01

    A reflector antenna computer program based upon a simple discreet approximation of the radiation integral has proven to be extremely easy to adapt to the parallel computing architecture of the modest number of large-gain computing elements such as are used in the Intel iPSC and Touchstone Delta parallel machines.

  12. Phoenix: Service Oriented Architecture for Information Management - Base Implementation Document

    DTIC Science & Technology

    2011-09-01

    architecture is a technical specification defined using UML . The conceptual architecture is a less formal description using plain language and diagrams to...provide design concepts and objectives. Diagram Conventions Throughout this document there are a number of non- UML diagrams that are used to...characterization and query capability associated with active streams. The design is fully documented using UML diagrams and a full complement of JUnit tests

  13. Shared Memory versus Message Passing Architectures: An Application Based Study

    DTIC Science & Technology

    1988-11-09

    Driven Processor [3.9]. things are rapidly changing. Using specialized routing chips and the technique of wormhole routing [6]. the network latencies...between the two which force tradeoffs between the two architectures. The shared memory architecture considered in this paper has a single global...application programmer to control the degree of consistency explicitly. In this paper . we explore several such tradeoffs between shared-memory and message

  14. a Cloud-Based Architecture for Smart Video Surveillance

    NASA Astrophysics Data System (ADS)

    Valentín, L.; Serrano, S. A.; Oves García, R.; Andrade, A.; Palacios-Alonso, M. A.; Sucar, L. Enrique

    2017-09-01

    Turning a city into a smart city has attracted considerable attention. A smart city can be seen as a city that uses digital technology not only to improve the quality of people's life, but also, to have a positive impact in the environment and, at the same time, offer efficient and easy-to-use services. A fundamental aspect to be considered in a smart city is people's safety and welfare, therefore, having a good security system becomes a necessity, because it allows us to detect and identify potential risk situations, and then take appropriate decisions to help people or even prevent criminal acts. In this paper we present an architecture for automated video surveillance based on the cloud computing schema capable of acquiring a video stream from a set of cameras connected to the network, process that information, detect, label and highlight security-relevant events automatically, store the information and provide situational awareness in order to minimize response time to take the appropriate action.

  15. a New Architecture for Intelligent Systems with Logic Based Languages

    NASA Astrophysics Data System (ADS)

    Saini, K. K.; Saini, Sanju

    2008-10-01

    People communicate with each other in sentences that incorporate two kinds of information: propositions about some subject, and metalevel speech acts that specify how the propositional information is used—as an assertion, a command, a question, or a promise. By means of speech acts, a group of people who have different areas of expertise can cooperate and dynamically reconfigure their social interactions to perform tasks and solve problems that would be difficult or impossible for any single individual. This paper proposes a framework for intelligent systems that consist of a variety of specialized components together with logic-based languages that can express propositions and speech acts about those propositions. The result is a system with a dynamically changing architecture that can be reconfigured in various ways: by a human knowledge engineer who specifies a script of speech acts that determine how the components interact; by a planning component that generates the speech acts to redirect the other components; or by a committee of components, which might include human assistants, whose speech acts serve to redirect one another. The components communicate by sending messages to a Linda-like blackboard, in which components accept messages that are either directed to them or that they consider themselves competent to handle.

  16. An architecture for distributed video applications based on declarative networking

    NASA Astrophysics Data System (ADS)

    Wang, Xiping; Gonzales, Cesar; Lobo, Jorge; Calo, Seraphin; Verma, Dinesh

    2012-06-01

    Video surveillance applications are examples of complex distributed coalition tasks. Real-time capture and analysis of image sensor data is one of the most important tasks in a number of military critical decision making scenarios. In complex battlefield situations, there is a need to coordinate the operation of distributed image sensors and the analysis of their data as transmitted over a heterogeneous wireless network where bandwidth, power, and computational capabilities are constrained. There is also a need to automate decision making based on the results of the analysis of video data. Declarative Networking is a promising technology for controlling complex video surveillance applications in this sort of environment. This paper presents a flexible and extensible architecture for deploying distributed video surveillance applications using the declarative networking paradigm, which allows us to dynamically connect and manage distributed image sensors and deploy various modules for the analysis of video data to satisfy a variety of video surveillance requirements. With declarative computing, it becomes possible for us not only to express the program control structure in a declarative fashion, but also to simplify the management of distributed video surveillance applications.

  17. Comparison of the Microwave Performance of Transparent Wire Monopole Antennas Based on Silver Films

    NASA Astrophysics Data System (ADS)

    Hautcoeur, J.; Castel, X.; Colombel, F.; Himdi, M.; Motta Cruz, E.

    2013-03-01

    In this paper, transparent printed lines used in microwave radiating structures are studied. Two transparent wire monopole antennas and an opaque reference counterpart are presented, compared, and discussed. The first transparent antenna was fabricated from a transparent conductive AgGL coating (silver grid layer: a silver/titanium bilayer deposited on a glass substrate and meshed by a standard photolithographic wet etching process). It exhibits optical transparency T of 59.2 ± 0.1% in the visible-light spectrum and sheet resistance R □ of 0.017 ± 0.001 Ω/□. The second transparent antenna was fabricated from a usual transparent conducting multilayer of indium tin oxide/silver/indium tin oxide, also deposited on a glass substrate. It exhibits optical transparency T of 71.3 ± 0.1% and sheet resistance R □ of 5.05 ± 0.05 Ω/□. Both transparent wire monopole antennas have been characterized for microwave performance and compared with an opaque reference counterpart made from a continuous silver/titanium bilayer deposited on the same glass substrate ( T = 0%, R □ = 0.0025 ± 0.0002 Ω/□). Microwave measurements show similar performance for the transparent AgGL antenna and opaque reference counterpart. At 2.05 GHz, their maximum measured gains are both 4.4 ± 0.3 dBi. Conversely, the transparent indium tin oxide/silver/indium tin oxide antenna presents significant ohmic loss due to its sheet resistance value and consequently a low measured gain value (-2.1 ± 0.3 dBi maximum). This study demonstrates the relevance of the AgGL coating in the fabrication of transparent wire monopole antennas.

  18. A Modified Lunar Reconnaissance Orbiter (LRO) High Gain Antenna (HGA) Controller Based on Flight Performance

    NASA Technical Reports Server (NTRS)

    Shah, Neerav

    2010-01-01

    The National Aeronautics and Space Administration's (NASA) Lunar Reconnaissance Orbiter (LRO) was launched on June 18, 2009 and is currently in a 50 km mean altitude polar orbit around the Moon. LRO was designed and built by the NASA Goddard Space Flight Center in Greenbelt, MD. The spacecraft is three-axis stabilized via the attitude control system (ACS), which is composed of various control modes using different sets of sensors and actuators. In addition to pointing the spacecraft, the ACS is responsible for pointing LRO s two appendages, the Solar Array (SA) and the High Gain Antenna (HGA). This study reviews LRO s HGA control system. Starting with an overview of the HGA system, the paper delves into the single input single output (SISO) linear analysis followed by the controller design. Based on flight results, an alternate control scheme is devised to address inherent features in the flight control system. The modified control scheme couples the HGA loop with the spacecraft pointing control loop, and through analysis is shown to be stable and improve transient performance. Although proposed, the LRO project decided against implementing this modification.

  19. Plasmon Enhanced Internal Photoemission in Antenna-Spacer-Mirror Based Au/TiO₂ Nanostructures.

    PubMed

    Fang, Yurui; Jiao, Yang; Xiong, Kunli; Ogier, Robin; Yang, Zhong-Jian; Gao, Shiwu; Dahlin, Andreas B; Käll, Mikael

    2015-06-10

    Emission of photoexcited hot electrons from plasmonic metal nanostructures to semiconductors is key to a number of proposed nanophotonics technologies for solar harvesting, water splitting, photocatalysis, and a variety of optical sensing and photodetector applications. Favorable materials and catalytic properties make systems based on gold and TiO2 particularly interesting, but the internal photoemission efficiency for visible light is low because of the wide bandgap of the semiconductor. We investigated the incident photon-to-electron conversion efficiency of thin TiO2 films decorated with Au nanodisk antennas in an electrochemical circuit and found that incorporation of a Au mirror beneath the semiconductor amplified the photoresponse for light with wavelength λ = 500-950 nm by a factor 2-10 compared to identical structures lacking the mirror component. Classical electrodynamics simulations showed that the enhancement effect is caused by a favorable interplay between localized surface plasmon excitations and cavity modes that together amplify the light absorption in the Au/TiO2 interface. The experimentally determined internal quantum efficiency for hot electron transfer decreases monotonically with wavelength, similar to the probability for interband excitations with energy higher than the Schottky barrier obtained from a density functional theory band structure simulation of a thin Au/TiO2 slab.

  20. Antenna pattern study

    NASA Technical Reports Server (NTRS)

    Harper, Warren

    1988-01-01

    Prediction of antenna radiation patterns has long been an important function in the design of command, communication, and tracking systems for rocket vehicles and spacecraft. An acceptable degree of assurance that a radio link will provide the required quality of data or certainty of correct command execution must be acquired by some means if the system is to be certified as reliable. Two methods have been used to perform this function: (1) Theoretical analysis, based on the known properties of basic antenna element types and their behavior in the presence of conductive structures of simple shape, and (2) Measurement of the patterns on scale models of the spacecraft or rocket vehicle on which the antenna is located. Both of these methods are ordinarily employed in the antenna design process.

  1. Micro-fabrication considerations for MEMS-based reconfigurable antenna apertures: with emphasis on DC bias network

    NASA Astrophysics Data System (ADS)

    Moghadas, Hamid; Mousavi, Pedram; Daneshmand, Mojgan

    2016-11-01

    This note addresses the main challenges involved in monolithic micro-fabrication of large capacitive-MEMS-based reconfigurable electromagnetic apertures in antenna applications. The fabrication of a large DC bias line network, and also the metallic features in such apertures, requires special attention and optimization. It is shown that the choice of DC bias network material can impact DC and RF performance of the structure, and a trade-off between switching time and radiation pattern integrity should be considered.

  2. Self-Powered Wireless Affinity-Based Biosensor Based on Integration of Paper-Based Microfluidics and Self-Assembled RFID Antennas.

    PubMed

    Yuan, Mingquan; Alocilja, Evangelyn C; Chakrabartty, Shantanu

    2016-08-01

    This paper presents a wireless, self-powered, affinity-based biosensor based on the integration of paper-based microfluidics with our previously reported method for self-assembling radio-frequency (RF) antennas. At the core of the proposed approach is a silver-enhancement technique that grows portions of a RF antenna in regions where target antigens hybridize with target specific affinity probes. The hybridization regions are defined by a network of nitrocellulose based microfluidic channels which implement a self-powered approach to sample the reagent and control its flow and mixing. The integration substrate for the biosensor has been constructed using polyethylene and the patterning of the antenna on the substrate has been achieved using a low-cost ink-jet printing technique. The substrate has been integrated with passive radio-frequency identification (RFID) tags to demonstrate that the resulting sensor-tag can be used for continuous monitoring in a food supply-chain where direct measurement of analytes is typically considered to be impractical. We validate the proof-of-concept operation of the proposed sensor-tag using IgG as a model analyte and using a 915 MHz Ultra-high-frequency (UHF) RFID tagging technology.

  3. A K-Band Linear Phased Array Antenna Based on Ba(0.60)Sr(0.40)TiO3 Thin Film Phase Shifters

    NASA Technical Reports Server (NTRS)

    Romanofsky, R.; Bernhard, J.; Washington, G.; VanKeuls, F.; Miranda, F.; Cannedy, C.

    2000-01-01

    This paper summarizes the development of a 23.675 GHz linear 16-element scanning phased array antenna based on thin ferroelectric film coupled microstripline phase shifters and microstrip patch radiators.

  4. Highly enhanced spontaneous emission with nanoshell-based metallodielectric hybrid antennas

    NASA Astrophysics Data System (ADS)

    Cheng, Yuqing; Lu, Guowei; shen, Hongming; Wang, Yuwei; He, Yingbo; Chou, R. Yuanying; Gong, Qihuang

    2015-09-01

    The metallodielectric hybrid nanoantenna integrating plasmonic nanostructures with dielectric planar substrate can improve the spontaneous emission greatly. We demonstrated that the performances of the hybrid antenna can be substantially optimized with specific plasmonic nanostructures by employing finite-difference time-domain method. The hybrid antenna with core-shell nanostructure can enhance spontaneous emission greatly rather than the individual spherical nanoparticle. Moreover, the performances of the hybrid antenna can be boosted further through using asymmetrical nanoshell. The mechanism of the high enhancement effect is due to the hybrid structure being able to couple efficiently with the electric field by a larger dipolar moment. And the emission directivity of the hybrid antenna is able to be modified by adjusting the geometry of the plasmonic nanostructures. The results should be beneficial for various fundamental and applied research fields, including single molecule fluorescence and surface enhance Raman spectroscopy, etc. The enhancement of spontaneous emission is in demand in fundamental interests and various applied research fields. However, the electromagnetic enhancement of single plasmonic nanostructure is limited due to intrinsic loss of metal materials and quantum tunneling effect which also limits the ability of enhancement of spontaneous emission. Interestingly, it was found that hybrid structures can provide higher enhancement effect. This study is about a kind new type of optical antenna to control spontaneous emission of single emitter, i.e. a metallodielectric hybrid nanoantenna integrating plasmonic nanostructures with dielectric planar substrate which can improve the spontaneous emission greatly. We demonstrated that the performances of the hybrid antenna can be substantially optimized with specific plasmonic nanostructures by employing finite-difference time-domain method. The hybrid antenna with core-shell nanostructure can enhance

  5. Distributed search engine architecture based on topic specific searches

    NASA Astrophysics Data System (ADS)

    Abudaqqa, Yousra; Patel, Ahmed

    2015-05-01

    Indisputably, search engines (SEs) abound. The monumental growth of users performing online searches on the Web is a contending issue in the contemporary world nowadays. For example, there are tens of billions of searches performed everyday, which typically offer the users many irrelevant results which are time consuming and costly to the user. Based on the afore-going problem it has become a herculean task for existing Web SEs to provide complete, relevant and up-to-date information response to users' search queries. To overcome this problem, we developed the Distributed Search Engine Architecture (DSEA), which is a new means of smart information query and retrieval of the World Wide Web (WWW). In DSEAs, multiple autonomous search engines, owned by different organizations or individuals, cooperate and act as a single search engine. This paper includes the work reported in this research focusing on development of DSEA, based on topic-specific specialised search engines. In DSEA, the results to specific queries could be provided by any of the participating search engines, for which the user is unaware of. The important design goal of using topic-specific search engines in the research is to build systems that can effectively be used by larger number of users simultaneously. Efficient and effective usage with good response is important, because it involves leveraging the vast amount of searched data from the World Wide Web, by categorising it into condensed focused topic -specific results that meet the user's queries. This design model and the development of the DSEA adopt a Service Directory (SD) to route queries towards topic-specific document hosting SEs. It displays the most acceptable performance which is consistent with the requirements of the users. The evaluation results of the model return a very high priority score which is associated with each frequency of a keyword.

  6. Notch Antennas

    NASA Technical Reports Server (NTRS)

    Lee, Richard Q.

    2004-01-01

    Notch antennas, also known as the tapered slot antenna (TSA), have been the topics of research for decades. TSA has demonstrated multi-octave bandwidth, moderate gain (7 to 10 dB), and symmetric E- and H- plane beam patterns and can be used for many different applications. This chapter summarizes the research activities on notch antennas over the past decade with emphasis on their most recent advances and applications. This chapter begins with some discussions on the designs of single TSA; then follows with detailed discussions of issues associated with TSA designs and performance characteristics. To conclude the chapter, some recent developments in TSA arrays and their applications are highlighted.

  7. A new planar broadband antenna based on meandered line loops for portable wireless communication devices

    NASA Astrophysics Data System (ADS)

    Alibakhshi-Kenari, Mohammad; Naser-Moghadasi, Mohammad; Sadeghzadeh, R. A.; Virdee, Bal S.; Limiti, Ernesto

    2016-07-01

    This article presents the design of a novel planar antenna structure comprising two pairs of interconnected meandered line loops that are grounded to a truncated T-shaped ground plane through two via holes. The T-shaped ground plane is used as a reflector to enhance the performance of the antenna. The resulting antenna is compact occupying an area of 38.5 × 36.6 mm2 (0.070λo × 0.067λo), where free-space wavelength is 550 MHz. The antenna radiates omnidirectionally in the E plane across its operational bandwidth (550 MHz to 3.85 GHz) with peak gain and efficiency of 5.5 dBi and 90.1%, respectively, at 2.35 GHz and reflection coefficient better than -10 dB. These characteristics make the antenna suitable for numerous applications, in particular, JCDMA, UHF RFID, GSM 900, GPS, KPCS, DCS, IMT-2000, WiMAX, WiFi, and Bluetooth.

  8. Microfluidic channel-based wireless charging and communication platform for microsensors with miniaturized onboard antenna

    NASA Astrophysics Data System (ADS)

    Duan, G.; Zhao, X.; Seren, H. R.; Chen, C.; Li, A.; Zhang, X.

    2016-12-01

    A double layer spiral antenna with side length of 380 μm was fabricated by a multi-step electroplating process, and integrated with a commercialized passive RFID chip to realize the RF power harvesting and communication functions of a microsensor. To power up and communicate with the microchips, a single layer spiral reader antenna was fabricated on top of a glass substrate with side length of 1 mm. The microchips and the reader antenna were both optimized at the frequency of 915 MHz. Due to the small size of the reader antenna, the strength of the magnetic field decreased dramatically along the axial direction of the reader antenna, which limited the working distance to within 1 mm. To enclose the microchips within the reading range, a three-layer microfluidic channel was designed and fabricated. The channel and cover layers were fabricated by laser cutting of acrylic sheets, and bonded with the glass substrate to form the channel. To operate multiple microchips simultaneously, separation and focusing function units were also designed. Low loss pump oil was used to transport the microchips flowing inside the channel. Within the reading area, the microchips were powered up, and their ID information was retrieved and displayed on the computer interface successfully.

  9. A Passive Temperature-Sensing Antenna Based on a Bimetal Strip Coil.

    PubMed

    Shi, Xianwei; Yang, Fan; Xu, Shenheng; Li, Maokun

    2017-03-23

    A passive temperature-sensing antenna is presented in this paper, which consists of a meandering dipole, a bimetal strip and a back cavity. The meandering dipole is divided into two parts: the lower feeding part and the upper radiating part, which maintain electric contact during operation. As a sensing component, a bimetal strip coil offers a twisting force to rotate the lower feeding part of the antenna when the temperature varies. As a result, the effective length of the dipole antenna changes, leading to a shift of the resonant frequency. Furthermore, a metal back cavity is added to increase the antenna's quality factor Q, which results in a high-sensitivity design. An antenna prototype is designed, fabricated, and measured, which achieves a sensitivity larger than 4.00 MHz/°C in a temperature range from 30 °C to 50 °C and a read range longer than 4 m. Good agreement between the simulation and measurement results is obtained.

  10. Wide Field-of-view and Broadband Terahertz Beam Steering Based on Gap Plasmon Geodesic Antennas

    PubMed Central

    Liu, Kaipeng; Guo, Yinghui; Pu, Mingbo; Ma, Xiaoliang; Li, Xiong; Luo, Xiangang

    2017-01-01

    Despite a plethora of applications ranging from wireless communications to sensing and spectroscopy, the current terahertz beam steering technologies suffer from tremendous insert loss, stringent control of electric bias, limited scanning angle, relatively complicated configuration and narrow operation bandwidth, preventing further practical application. We propose and demonstrate a conceptually new approach for terahertz beam steering by virtue of gap plasmon geodesic antennas. By adjusting the geometric dimension of the gap plasmon geodesic antennas, all gap plasmon modes add coherently along a peculiar direction that depends on the geodesic mean surface. Consequently, high directive beams are generated through the antenna, whose direction could be changed within a wide-angle range spanning ±45° by lateral motion of the feed. Furthermore, an assembled antenna structure consisting of four-element geodesic antennas array is proposed for full 360° beam steering, which can operate in a broadband range from 0.8 THz to 1.2 THz. PMID:28134324

  11. Wireless thin film transistor based on micro magnetic induction coupling antenna

    NASA Astrophysics Data System (ADS)

    Jun, Byoung Ok; Lee, Gwang Jun; Kang, Jong Gu; Kim, Seunguk; Choi, Ji-Woong; Cha, Seung Nam; Sohn, Jung Inn; Jang, Jae Eun

    2015-12-01

    A wireless thin film transistor (TFT) structure in which a source/drain or a gate is connected directly to a micro antenna to receive or transmit signals or power can be an important building block, acting as an electrical switch, a rectifier or an amplifier, for various electronics as well as microelectronics, since it allows simple connection with other devices, unlike conventional wire connections. An amorphous indium gallium zinc oxide (α-IGZO) TFT with magnetic antenna structure was fabricated and studied for this purpose. To enhance the induction coupling efficiency while maintaining the same small antenna size, a magnetic core structure consisting of Ni and nanowires was formed under the antenna. With the micro-antenna connected to a source/drain or a gate of the TFT, working electrical signals were well controlled. The results demonstrated the device as an alternative solution to existing wire connections which cause a number of problems in various fields such as flexible/wearable devices, body implanted devices, micro/nano robots, and sensors for the ‘internet of things’ (IoT).

  12. Wireless thin film transistor based on micro magnetic induction coupling antenna.

    PubMed

    Jun, Byoung Ok; Lee, Gwang Jun; Kang, Jong Gu; Kim, Seunguk; Choi, Ji-Woong; Cha, Seung Nam; Sohn, Jung Inn; Jang, Jae Eun

    2015-12-22

    A wireless thin film transistor (TFT) structure in which a source/drain or a gate is connected directly to a micro antenna to receive or transmit signals or power can be an important building block, acting as an electrical switch, a rectifier or an amplifier, for various electronics as well as microelectronics, since it allows simple connection with other devices, unlike conventional wire connections. An amorphous indium gallium zinc oxide (α-IGZO) TFT with magnetic antenna structure was fabricated and studied for this purpose. To enhance the induction coupling efficiency while maintaining the same small antenna size, a magnetic core structure consisting of Ni and nanowires was formed under the antenna. With the micro-antenna connected to a source/drain or a gate of the TFT, working electrical signals were well controlled. The results demonstrated the device as an alternative solution to existing wire connections which cause a number of problems in various fields such as flexible/wearable devices, body implanted devices, micro/nano robots, and sensors for the 'internet of things' (IoT).

  13. Wireless thin film transistor based on micro magnetic induction coupling antenna

    PubMed Central

    Jun, Byoung Ok; Lee, Gwang Jun; Kang, Jong Gu; Kim, Seunguk; Choi, Ji-Woong; Cha, Seung Nam; Sohn, Jung Inn; Jang, Jae Eun

    2015-01-01

    A wireless thin film transistor (TFT) structure in which a source/drain or a gate is connected directly to a micro antenna to receive or transmit signals or power can be an important building block, acting as an electrical switch, a rectifier or an amplifier, for various electronics as well as microelectronics, since it allows simple connection with other devices, unlike conventional wire connections. An amorphous indium gallium zinc oxide (α-IGZO) TFT with magnetic antenna structure was fabricated and studied for this purpose. To enhance the induction coupling efficiency while maintaining the same small antenna size, a magnetic core structure consisting of Ni and nanowires was formed under the antenna. With the micro-antenna connected to a source/drain or a gate of the TFT, working electrical signals were well controlled. The results demonstrated the device as an alternative solution to existing wire connections which cause a number of problems in various fields such as flexible/wearable devices, body implanted devices, micro/nano robots, and sensors for the ‘internet of things’ (IoT). PMID:26691929

  14. Science Possibilities Enabled by the Mars Base Camp Human Exploration Architecture

    NASA Astrophysics Data System (ADS)

    Cichan, T.; Murrow, D. W.; Jolly, S. D.; Bierhaus, E. B.; Clark, B.

    2017-02-01

    The Mars Base Camp architecture study reveals scientific possibilities enabled by a crewed orbital base camp, and that collaborative human and robotic missions should be part of the vision for Mars exploration by 2050.

  15. Exploration Space Suit Architecture: Destination Environmental-Based Technology Development

    NASA Technical Reports Server (NTRS)

    Hill, Terry R.

    2010-01-01

    This paper picks up where EVA Space Suit Architecture: Low Earth Orbit Vs. Moon Vs. Mars (Hill, Johnson, IEEEAC paper #1209) left off in the development of a space suit architecture that is modular in design and interfaces and could be reconfigured to meet the mission or during any given mission depending on the tasks or destination. This paper will walk though the continued development of a space suit system architecture, and how it should evolve to meeting the future exploration EVA needs of the United States space program. In looking forward to future US space exploration and determining how the work performed to date in the CxP and how this would map to a future space suit architecture with maximum re-use of technology and functionality, a series of thought exercises and analysis have provided a strong indication that the CxP space suit architecture is well postured to provide a viable solution for future exploration missions. Through the destination environmental analysis that is presented in this paper, the modular architecture approach provides the lowest mass, lowest mission cost for the protection of the crew given any human mission outside of low Earth orbit. Some of the studies presented here provide a look and validation of the non-environmental design drivers that will become every-increasingly important the further away from Earth humans venture and the longer they are away. Additionally, the analysis demonstrates a logical clustering of design environments that allows a very focused approach to technology prioritization, development and design that will maximize the return on investment independent of any particular program and provide architecture and design solutions for space suit systems in time or ahead of being required for any particular manned flight program in the future. The new approach to space suit design and interface definition the discussion will show how the architecture is very adaptable to programmatic and funding changes with

  16. A Generic Software Architecture for Deception-Based Intrusion Detection and Response Systems

    DTIC Science & Technology

    2003-03-01

    known as Aikido [37]. Michael et al. [2] proposed a high-level architecture for software decoys, shown in Figure II.3. The architecture is based on...14, no.3, pp. 54-62, 1999. [37] Westbrook, A., Ratti, O., Aikido and the Dynamic Sphere, Charles E. Tuttle Co., September 1994. [38] Ellison, R.J

  17. Collaborative Concept Mapping in a Web-Based Learning Environment: A Pedagogic Experience in Architectural Education.

    ERIC Educational Resources Information Center

    Madrazo, Leandro; Vidal, Jordi

    2002-01-01

    Describes a pedagogical work, carried out within a school of architecture, using a Web-based learning environment to support collaborative understanding of texts on architectural theory. Explains the use of concept maps, creation of a critical vocabulary, exploration of semantic spaces, and knowledge discovery through navigation. (Author/LRW)

  18. Collaborative Concept Mapping in a Web-Based Learning Environment: A Pedagogic Experience in Architectural Education.

    ERIC Educational Resources Information Center

    Madrazo, Leandro; Vidal, Jordi

    2002-01-01

    Describes a pedagogical work, carried out within a school of architecture, using a Web-based learning environment to support collaborative understanding of texts on architectural theory. Explains the use of concept maps, creation of a critical vocabulary, exploration of semantic spaces, and knowledge discovery through navigation. (Author/LRW)

  19. A system-theoretical, architecture-based approach to ontology management.

    PubMed

    Blobel, Bernd; Brochhausen, Mathias; González, Carolina; Lopez, Diego M; Oemig, Frank

    2012-01-01

    Comprehensive interoperability between distributed eHealth/pHealth environments requires that the systems involved are based on a common architectural framework and share common knowledge. The paper deals with the representation of systems by related ontologies. Therefore, the architectural principles ruling the system design and the interrelations of its components also rule the design of those ontologies and their management as exemplified.

  20. Developing a Conceptual Architecture for a Generalized Agent-based Modeling Environment (GAME)

    DTIC Science & Technology

    2008-03-01

    possible. A conceptual architecture for a generalized agent- based modeling environment (GAME) based upon design principles from OR/MS systems was created...conceptual architecture for a generalized agent-based modeling environment (GAME) based upon design principles from OR/MS systems was created that...handle the event, and subsequently form the relevant plans. One of these plans will be selected, and either pushed to the top of the current

  1. Development of a class of antennas for space-based Navstar GPS applications

    NASA Technical Reports Server (NTRS)

    Tranquilla, J. M.; Colpitts, B. G.

    1989-01-01

    This paper describes the performance of several unique antenna/ground plane configurations currently being developed for the TOPEX satellite and which may also be used for improved ground station operation. These antennas are designed with the objective of achieving nearly hemispherical coverage with sharp pattern cutoff above the horizon together with uniform phase response over the entire coverage area. The most promising of these designs is a uniform choke ring approximately 2 lambda in diameter. The ground planes, when used with the Dorne-Margolin C246 antenna element, produce smooth pattern cutoff of the order of 0.25 dB per deg over 135 deg, excellent LCP rejection, and rms phase deviation of 5-5.7 deg. Other ground plane designs, including larger choke ring structures, slotted ground planes, and the use of absorber material, proved much less effective.

  2. Prediction of Slot Shape and Slot Size for Improving the Performance of Microstrip Antennas Using Knowledge-Based Neural Networks

    PubMed Central

    De, Asok

    2014-01-01

    In the last decade, artificial neural networks have become very popular techniques for computing different performance parameters of microstrip antennas. The proposed work illustrates a knowledge-based neural networks model for predicting the appropriate shape and accurate size of the slot introduced on the radiating patch for achieving desired level of resonance, gain, directivity, antenna efficiency, and radiation efficiency for dual-frequency operation. By incorporating prior knowledge in neural model, the number of required training patterns is drastically reduced. Further, the neural model incorporated with prior knowledge can be used for predicting response in extrapolation region beyond the training patterns region. For validation, a prototype is also fabricated and its performance parameters are measured. A very good agreement is attained between measured, simulated, and predicted results. PMID:27382616

  3. Graphene-based fine-tunable optical delay line for optical beamforming in phased-array antennas.

    PubMed

    Tatoli, Teresa; Conteduca, Donato; Dell'Olio, Francesco; Ciminelli, Caterina; Armenise, Mario N

    2016-06-01

    The design of an integrated graphene-based fine-tunable optical delay line on silicon nitride for optical beamforming in phased-array antennas is reported. A high value of the optical delay time (τg=920  ps) together with a compact footprint (4.15  mm2) and optical loss <27  dB make this device particularly suitable for highly efficient steering in active phased-array antennas. The delay line includes two graphene-based Mach-Zehnder interferometer switches and two vertically stacked microring resonators between which a graphene capacitor is placed. The tuning range is obtained by varying the value of the voltage applied to the graphene electrodes, which controls the optical path of the light propagation and therefore the delay time. The graphene provides a faster reconfigurable time and low values of energy dissipation. Such significant advantages, together with a negligible beam-squint effect, allow us to overcome the limitations of conventional RF beamformers. A highly efficient fine-tunable optical delay line for the beamsteering of 20 radiating elements up to ±20° in the azimuth direction of a tile in a phased-array antenna of an X-band synthetic aperture radar has been designed.

  4. LDEF (Postflight), AO133 : Effect of Space Environment on Space-Based Radar Phased-Array Antenna, Tr

    NASA Technical Reports Server (NTRS)

    1990-01-01

    LDEF (Postflight), AO133 : Effect of Space Environment on Space-Based Radar Phased-Array Antenna, Tray H07 The postflight photograph was taken in the KSC SAEF II facility after the experiment was removed from the LDEF. The Space-Based Radar (SBR) Phased-Array Antenna occupies a six (6) inch deep LDEF end corner tray located on the space end of the LDEF. A light tan discoloration is visible on the left and lower flanges of the experiment tray and also on the unpainted aluminum filler to the left of the passive part of the experiment. A darker stain has discolored the lower corners of the tray structure. The SBR Phased-Array Antenna experiment, consisting of an active part in the upper half of the tray and a passive part located in the lower half of the experiment tray, appears to be intact with no apparent physical damage. The black thermal coating on the active part of the experiment appears to have changed from a flat black to a dark gray while the coating on the passive part of the experiment appears less degraded. The exposed Kapton specimen surfaces in both the active and passive parts of the experiment appear to have changed from specular to diffuse from exposure to the space environment.

  5. Synthetic Adhesive Attachment Discs based on Spider Pyriform Silk Architecture

    NASA Astrophysics Data System (ADS)

    Jain, Dharamdeep; Sahni, Vasav; Dhinojwala, Ali

    2014-03-01

    Among the variety of silks produced by spiders, pyriform silk is used in conjunction with the dragline silk to attach webs to different surfaces. Cob weaver spiders employ different architectural patterns to utilize the pyriform silk and form attachment joints with each pattern having a characteristic adhesive performance. The staple pin architecture is a one of the strongest attachment designs employed by spiders to attach their webs. Here we use a synthetic approach to create the a similar patterned architecture attachment discs on aluminum substrate using thermoplastic polyurethane. Measurable pull off forces are generated when the synthetic discs are peeled off a surface. This innovative adhesive strategy can be a source of design in various biomedical applications. Financial Support from National Science Foundation.

  6. Neural architecture design based on extreme learning machine.

    PubMed

    Bueno-Crespo, Andrés; García-Laencina, Pedro J; Sancho-Gómez, José-Luis

    2013-12-01

    Selection of the optimal neural architecture to solve a pattern classification problem entails to choose the relevant input units, the number of hidden neurons and its corresponding interconnection weights. This problem has been widely studied in many research works but their solutions usually involve excessive computational cost in most of the problems and they do not provide a unique solution. This paper proposes a new technique to efficiently design the MultiLayer Perceptron (MLP) architecture for classification using the Extreme Learning Machine (ELM) algorithm. The proposed method provides a high generalization capability and a unique solution for the architecture design. Moreover, the selected final network only retains those input connections that are relevant for the classification task. Experimental results show these advantages. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. New Architecture for Reagentless, Protein-Based Electrochemical Biosensors.

    PubMed

    Kang, Di; Sun, Sheng; Kurnik, Martin; Morales, Demosthenes; Dahlquist, Frederick W; Plaxco, Kevin W

    2017-09-06

    Here we demonstrate a new class of reagentless, single-step sensors for the detection of proteins and peptides that is the electrochemical analog of fluorescence polarization (fluorescence anisotropy), a versatile optical approach widely employed to this same end. Our electrochemical sensors consist of a redox-reporter-modified protein (the "receptor") site-specifically anchored to an electrode via a short, flexible polypeptide linker. Interaction of the receptor with its binding partner alters the efficiency with which the reporter approaches the electrode surface, thus causing a change in redox current upon voltammetric interrogation. As our first proof-of-principle we employed the bacterial chemotaxis protein CheY as our receptor. Interaction with either of CheY's two binding partners, the P2 domain of the chemotaxis kinase, CheA, or the 16-residue "target region" of the flagellar switch protein, FliM, leads to easily measurable changes in output current that trace Langmuir isotherms within error of those seen in solution. Phosphorylation of the electrode-bound CheY decreases its affinity for CheA-P2 and enhances its affinity for FliM in a manner likewise consistent with its behavior in solution. As expected given the proposed sensor signaling mechanism, the magnitude of the binding-induced signal change depends on the placement of the redox reporter on the receptor. Following these preliminary studies with CheY, we also developed and characterized additional sensors aimed at the detection of specific antibodies using the relevant protein antigens as the receptor. These exhibit excellent detection limits for their targets without the use of reagents or wash steps. This novel, protein-based electrochemical sensing architecture provides a new and potentially promising approach to sensors for the single-step measurement of specific proteins and peptides.

  8. Sub-wavelength quarter-wave plate based on plasmonic patch antennas

    NASA Astrophysics Data System (ADS)

    Zhao, Hang; Yang, Yuanqing; Li, Qiang; Qiu, Min

    2013-12-01

    A quarter-wave plate using plasmonic patch antennas has been investigated. The nanostructures can convert linear polarized light into circular polarized light in the visible range (633 nm). By further exploiting the dimer patch antenna structure composed of different metals, directional emission (with a directivity of 4.8) of circular polarized light (with a conversion efficiency of 27.8%) in an oblique direction with respect to the incident light is enabled. Compared with previous designs, the proposed structures are ultra-thin, and are more suitable for integration applications.

  9. Electric arc localization based on antenna arrays and MUSIC direction of arrival estimation

    NASA Astrophysics Data System (ADS)

    Paun, Mirel; Digulescu, Angela; Tamas, Razvan; Ioana, Cornel

    2015-02-01

    This paper presents an application of antenna arrays and MUSIC algorithm for estimating the location of an electric arc source. The proposed technique can be used to localize arc faults in photovoltaic arrays and their associated transformation stations. The technique was implemented and tested in the laboratory. For this purpose, an experimental setup consisting of 4 antennas, a digital storage oscilloscope with computer connectivity and a PC (Personal Computer) for data processing was built. The results proved that the proposed method is able to estimate the direction of the electric arc source with reasonable accuracy.

  10. Practical Application of Model-based Programming and State-based Architecture to Space Missions

    NASA Technical Reports Server (NTRS)

    Horvath, Gregory A.; Ingham, Michel D.; Chung, Seung; Martin, Oliver; Williams, Brian

    2006-01-01

    Innovative systems and software engineering solutions are required to meet the increasingly challenging demands of deep-space robotic missions. While recent advances in the development of an integrated systems and software engineering approach have begun to address some of these issues, they are still at the core highly manual and, therefore, error-prone. This paper describes a task aimed at infusing MIT's model-based executive, Titan, into JPL's Mission Data System (MDS), a unified state-based architecture, systems engineering process, and supporting software framework. Results of the task are presented, including a discussion of the benefits and challenges associated with integrating mature model-based programming techniques and technologies into a rigorously-defined domain specific architecture.

  11. Practical Application of Model-based Programming and State-based Architecture to Space Missions

    NASA Technical Reports Server (NTRS)

    Horvath, Gregory A.; Ingham, Michel D.; Chung, Seung; Martin, Oliver; Williams, Brian

    2006-01-01

    Innovative systems and software engineering solutions are required to meet the increasingly challenging demands of deep-space robotic missions. While recent advances in the development of an integrated systems and software engineering approach have begun to address some of these issues, they are still at the core highly manual and, therefore, error-prone. This paper describes a task aimed at infusing MIT's model-based executive, Titan, into JPL's Mission Data System (MDS), a unified state-based architecture, systems engineering process, and supporting software framework. Results of the task are presented, including a discussion of the benefits and challenges associated with integrating mature model-based programming techniques and technologies into a rigorously-defined domain specific architecture.

  12. Multi-band Microwave Antennas and Devices based on Generalized Negative-Refractive-Index Transmission Lines

    NASA Astrophysics Data System (ADS)

    Ryan, Colan Graeme Matthew

    Focused on the quad-band generalized negative-refractive-index transmission line (G-NRI-TL), this thesis presents a variety of novel printed G-NRI-TL multi-band microwave device and antenna prototypes. A dual-band coupled-line coupler, an all-pass G-NRI-TL bridged-T circuit, a dual-band metamaterial leaky-wave antenna, and a multi-band G-NRI-TL resonant antenna are all new developments resulting from this research. In addition, to continue the theme of multi-band components, negative-refractive-index transmission lines are used to create a dual-band circularly polarized transparent patch antenna and a two-element wideband decoupled meander antenna system. High coupling over two independently-specified frequency bands is the hallmark of the G-NRI-TL coupler: it is 0.35lambda0 long but achieves approximately -3 dB coupling over both bands with a maximum insertion loss of 1 dB. This represents greater design flexibility than conventional coupled-line couplers and less loss than subsequent G-NRI-TL couplers. The single-ended bridged-T G-NRI-TL offers a metamaterial unit cell with an all-pass magnitude response up to 8 GHz, while still preserving the quad-band phase response of the original circuit. It is shown how the all-pass response leads to wider bandwidths and improved matching in quad-band inverters, power dividers, and hybrid couplers. The dual-band metamaterial leaky-wave antenna presented here was the first to be reported in the literature, and it allows broadside radiation at both 2 GHz and 6 GHz without experiencing the broadside stopband common to conventional periodic antennas. Likewise, the G-NRI-TL resonant antenna is the first reported instance of such a device, achieving quad-band operation between 2.5 GHz and 5.6 GHz, with a minimum radiation efficiency of 80%. Negative-refractive-index transmission line loading is applied to two devices: an NRI-TL meander antenna achieves a measured 52% impedance bandwidth, while a square patch antenna incorporates

  13. Exploratory Inquiry: Disparate Air Force Base Area Network Architectures

    DTIC Science & Technology

    2005-03-01

    Lieutenant Jamie Sharkey conducted a thesis on the key issues pertaining to Air Force enterprise architecture management. Discussion of...experience in fixed and tactical communications. His first duty station was McGuire AFB, New Jersey followed by assignments to Spangdahlem AB, Germany; the

  14. Component Architectures and Web-Based Learning Environments

    ERIC Educational Resources Information Center

    Ferdig, Richard E.; Mishra, Punya; Zhao, Yong

    2004-01-01

    The Web has caught the attention of many educators as an efficient communication medium and content delivery system. But we feel there is another aspect of the Web that has not been given the attention it deserves. We call this aspect of the Web its "component architecture." Briefly it means that on the Web one can develop very complex…

  15. Architecture-Based Reliability Analysis of Web Services

    ERIC Educational Resources Information Center

    Rahmani, Cobra Mariam

    2012-01-01

    In a Service Oriented Architecture (SOA), the hierarchical complexity of Web Services (WS) and their interactions with the underlying Application Server (AS) create new challenges in providing a realistic estimate of WS performance and reliability. The current approaches often treat the entire WS environment as a black-box. Thus, the sensitivity…

  16. Architecture-Based Reliability Analysis of Web Services

    ERIC Educational Resources Information Center

    Rahmani, Cobra Mariam

    2012-01-01

    In a Service Oriented Architecture (SOA), the hierarchical complexity of Web Services (WS) and their interactions with the underlying Application Server (AS) create new challenges in providing a realistic estimate of WS performance and reliability. The current approaches often treat the entire WS environment as a black-box. Thus, the sensitivity…

  17. A Multiprocessor-Based Sensor Fusion Software Architecture

    NASA Astrophysics Data System (ADS)

    Moxon, Bruce C.

    1988-03-01

    The ability to reason with information from a variety of sources is critical to the development of intelligent autonomous systems. Multisensor integration, or sensor fusion, is an area of research that attempts to provide a computational framework in which such perceptual reasoning can quickly and effectively be applied, enabling autonomous systems to function in unstructured, unconstrained environments. In this paper, the fundamental characteristics of the sensor fusion problem are explored. An hierarchical sensor fusion software architecture is presented as a computational framework in which information from complementary sensors is effectively combined. The concept of a sensor fusion pyramid is introduced, along with three unique computational abstractions: virtual sensors, virtual effectors, and focus of attention processing. The computing requirements of this sensor fusion architecture are investigated, and the blackboard system model is proposed as a computational methodology on which to build a sensor fusion software architecture. Finally, the Butterfly Parallel Processor is presented as a computer architecture that provides the computational capabilities required to support these intelligent systems applications.

  18. Analysis of SAR distribution in human head of antenna used in wireless power transform based on magnetic resonance.

    PubMed

    Gong, Feixiang; Wei, Zhiqiang; Cong, Yanping; Chi, Haokun; Yin, Bo; Sun, Mingui

    2017-07-20

    In this paper, a novel wireless power transfer antenna system was designed for human head implantable devices. The antenna system used the structure of three plates and four coils and operated at low frequencies to transfer power via near field. In order to verify the electromagnetic radiation safety on the human head, the electromagnetic intensity and specific absorption rate (SAR) were studied by finite-difference-time-domain (FDTD) method. A three-layer model of human head including skin, bone and brain tissues was constructed. The transmitting and receiving antenna were set outside and inside the model. The local and average SAR were simulated at the resonance frequency of 18.67 MHz in two situations, in one scenario both transmitting and receiving coil worked, while in the other scenario only the transmitting coil worked. The results showed that the maximum of 10 g SAR average value of human thoracic were 0.142 W/kg and 0.148 W/kg, respectively, both were lower than the international safety standards for human body of the ICNIRP and FCC, which verified the safety of the human body in wireless power transmission based on magnetic coupling resonance.

  19. Low-Profile UHF Antenna Design Based on an Anisotropic Transverse Resonance Condition

    DTIC Science & Technology

    2014-08-01

    MHz, which makes them unsuitable as substrates for UHF antenna structures. The availability of artificial magnetic metamaterials has widened the...Furthermore, the development of artificial magnetic metamaterials allows engineers to separately control the values of both magnetic permeability and...conditions with the conducting walls of the cavity. Furthermore, this report demonstrates that using anisotropic magnetic metamaterials to load this

  20. Dielectric parameter estimation of novel magneto-dielectric substrate based microstrip antenna

    NASA Astrophysics Data System (ADS)

    Saini, Ashish; Kumar, P.; Ravelo, B.; Thakur, Atul; Thakur, Preeti

    2016-05-01

    The effective relative permittivity and effective relative permeability of magneto-dielectric materials when used as substrate for microstrip antenna shows interdependency. This dependency was analyzed through simulation and verified by synthesizing nano composite ferrite. The 40nm nano crystallite size particles were synthesized using a co- precipitation method. Matching values of complex permittivity (ɛ* = 4.2-0.1j) and complex permeability (μ* = 4.3-0.2j) at 1 GHz were obtained from the electromagnetic characterization. The microstrip antenna with coaxial feed was fabricated and the interdependence of relative permittivity and relative permeability was verified. An error of 7% in the drawn length was observed for ɛr and μr of the order of 4. The magneto-dielectric material with composition Mn0.5Zn0.3Co0.2Fe2O4+BaFe12O19 proposed in this paper definitely can be proposed as a substrate material for miniaturized antenna. The antenna with desired resonant frequency can be fabricated by calculating the effective medium parameters as discussed in the paper.

  1. A MEMS-based tunable coplanar patch antenna fabricated using PCB processing techniques

    NASA Astrophysics Data System (ADS)

    Maddela, M.; Ramadoss, R.; Lempkowski, R.

    2007-04-01

    In this paper, a tunable coplanar rectangular patch antenna (CPA) designed using a MEMS varactor is reported. The MEMS varactor is monolithically integrated with the antenna on Duroid substrate using printed circuit processing techniques. Specifically, the MEMS varactor located at one of the radiating edges capacitively loads the CPA. The resonant frequency of the antenna is tuned electrostatically by applying a DC bias voltage between the MEMS varactor and the actuation pad on the antenna. The movable MEMS varactor membrane deflects downward toward the actuation pad due to an electrostatic force of attraction caused by the applied DC bias voltage. The deflection of the varactor membrane decreases the air gap, thereby increasing the loading capacitance. The increase in the loading capacitance results in a downward shift in the resonant frequency of the CPA. The CPA is center fed at the second radiating edge using a 50 Ω CPW feed line. The CPA operates in the frequency range from 5.185 to 5.545 GHz corresponding to the down and up states of the varactor. The tunable frequency range is about 360 MHz and the return loss is better than 40 dB in the entire tuning range. In this tuning range, the required DC voltage is in the range of 0-116 V.

  2. Analysis of performance of high light-energy-utilization-ratio laser communication antenna based on axicon

    NASA Astrophysics Data System (ADS)

    Wang, Chao; Li, Ying-chao; Jiang, Lun; Liu, Zhuang

    2016-01-01

    According to the transverse intensity distribution of the TEM00 Gaussian light field and character of an irradiance redistribution element, we proposed a novel method, which has the advantages of high light-energy-utilization-ratio (LEUR). The current laser communication (LASCOM) antenna frequently employs the Cassegrain reflective optical structure, in which the secondary mirror will introduce a center obscuration, leading to high ratio of transmitting power loss. To solve this problem, we make the transmitting beam pass through double convex axicons. The Gaussian peak of incident light coming into the central part of such element, will go out from near the peripheral part of the second axicon, and the edge part of Gaussian beam will go out from the central part. When the changed beam passes the Cassegrain structure, the utilizing efficiency will be raised obviously. In the paper, on different obscuration rate, the LEURs of LASCOM system before and after using the axicons are compared. In addition, the far-field intensity distribution of the laser beam changed by the axicon pair and transmitted by the antenna is calculated. The simulation result shows that the LEURs of antenna with and without an axicon pair are 91.7% and 28.9% on a Line obscuration ratio of 1/4. After a propagation of 1000 km, the far-field energy distribution of the hollow beam translated by the high LEUR antenna is closer to a flattop beam than that for the common Gaussian beam.

  3. Wrap-rib antenna concept development overview

    NASA Technical Reports Server (NTRS)

    Woods, A. A., Jr.; Garcia, N. F.

    1983-01-01

    The wrap rib antenna design of a parabolic reflector large space antenna is discussed. Cost estimates, design/mission compatibility, deployment sequence, ground based tests, and fabrication are discussed.

  4. A VLSI Architecture for Output Probability Computations of HMM-Based Recognition Systems with Store-Based Block Parallel Processing

    NASA Astrophysics Data System (ADS)

    Nakamura, Kazuhiro; Yamamoto, Masatoshi; Takagi, Kazuyoshi; Takagi, Naofumi

    In this paper, a fast and memory-efficient VLSI architecture for output probability computations of continuous Hidden Markov Models (HMMs) is presented. These computations are the most time-consuming part of HMM-based recognition systems. High-speed VLSI architectures with small registers and low-power dissipation are required for the development of mobile embedded systems with capable human interfaces. We demonstrate store-based block parallel processing (StoreBPP) for output probability computations and present a VLSI architecture that supports it. When the number of HMM states is adequate for accurate recognition, compared with conventional stream-based block parallel processing (StreamBPP) architectures, the proposed architecture requires fewer registers and processing elements and less processing time. The processing elements used in the StreamBPP architecture are identical to those used in the StoreBPP architecture. From a VLSI architectural viewpoint, a comparison shows the efficiency of the proposed architecture through efficient use of registers for storing input feature vectors and intermediate results during computation.

  5. Cluster based architecture and network maintenance protocol for medical priority aware cognitive radio based hospital.

    PubMed

    Al Mamoon, Ishtiak; Muzahidul Islam, A K M; Baharun, Sabariah; Ahmed, Ashir; Komaki, Shozo

    2016-08-01

    Due to the rapid growth of wireless medical devices in near future, wireless healthcare services may face some inescapable issue such as medical spectrum scarcity, electromagnetic interference (EMI), bandwidth constraint, security and finally medical data communication model. To mitigate these issues, cognitive radio (CR) or opportunistic radio network enabled wireless technology is suitable for the upcoming wireless healthcare system. The up-to-date research on CR based healthcare has exposed some developments on EMI and spectrum problems. However, the investigation recommendation on system design and network model for CR enabled hospital is rare. Thus, this research designs a hierarchy based hybrid network architecture and network maintenance protocols for previously proposed CR hospital system, known as CogMed. In the previous study, the detail architecture of CogMed and its maintenance protocols were not present. The proposed architecture includes clustering concepts for cognitive base stations and non-medical devices. Two cluster head (CH selector equations are formulated based on priority of location, device, mobility rate of devices and number of accessible channels. In order to maintain the integrity of the proposed network model, node joining and node leaving protocols are also proposed. Finally, the simulation results show that the proposed network maintenance time is very low for emergency medical devices (average maintenance period 9.5 ms) and the re-clustering effects for different mobility enabled non-medical devices are also balanced.

  6. A CSP-Based Agent Modeling Framework for the Cougaar Agent-Based Architecture

    NASA Technical Reports Server (NTRS)

    Gracanin, Denis; Singh, H. Lally; Eltoweissy, Mohamed; Hinchey, Michael G.; Bohner, Shawn A.

    2005-01-01

    Cognitive Agent Architecture (Cougaar) is a Java-based architecture for large-scale distributed agent-based applications. A Cougaar agent is an autonomous software entity with behaviors that represent a real-world entity (e.g., a business process). A Cougaar-based Model Driven Architecture approach, currently under development, uses a description of system's functionality (requirements) to automatically implement the system in Cougaar. The Communicating Sequential Processes (CSP) formalism is used for the formal validation of the generated system. Two main agent components, a blackboard and a plugin, are modeled as CSP processes. A set of channels represents communications between the blackboard and individual plugins. The blackboard is represented as a CSP process that communicates with every agent in the collection. The developed CSP-based Cougaar modeling framework provides a starting point for a more complete formal verification of the automatically generated Cougaar code. Currently it is used to verify the behavior of an individual agent in terms of CSP properties and to analyze the corresponding Cougaar society.

  7. Superconducting Microstrip Antennas: An Experimental Comparison of Two Feeding Methods

    NASA Technical Reports Server (NTRS)

    Richard, Mark A.; Claspy, Paul C.; Bhasin, Kul B.

    1993-01-01

    The recent discovery of high-temperature superconductors (HTSs) has generated a substantial amount of interest in microstrip antenna applications. However, the high permittivity of substrates compatible with HTS causes difficulty in feeding such antennas because of the high patch edge impedance. Two methods for feeding HTS microstrip antennas at K- and Ka-band are examined. Superconducting microstrip antennas that are directly coupled and gas-coupled to a microstrip transmission line have been designed and fabricated on lanthanum aluminate substrates using Y-Ba-Cu-O superconducting thin films. Measurements from these antennas, including input impedance, bandwidth, efficiency, and patterns, are presented and compared with published models. The measured results demonstrate that usable antennas can be constructed using either of these architectures, although the antennas suffer from narrow bandwidths. In each case, the HTS antenna shows a substantial improvement over an identical antenna made with normal metals

  8. Superconducting microstrip antennas - An experimental comparison of two feeding methods

    NASA Technical Reports Server (NTRS)

    Richard, M. A.; Bhasin, Kul B.; Claspy, Paul C.

    1993-01-01

    The recent discovery of high-temperature superconductors (HTSs) has generated a substantial amount of interest in microstrip antenna applications. However, the high permittivity of substrates compatible with HTS causes difficulty in feeding such antennas because of the high patch edge impedance. Two methods for feeding HTS microstrip antennas at K- and Ka-band are examined. Superconducting microstrip antennas that are directly coupled and gap-coupled to a microstrip transmission line have been designed and fabricated on lanthanum aluminate substrates using Y-Ba-Cu-O superconducting thin films. Measurements from these antennas, including input impedance, bandwidth, efficiency, and patterns, are presented and compared with published models. The measured results demonstrate that usable antennas can be constructed using either of these architectures, although the antennas suffer from narrow bandwidths. In each case, the HTS antenna shows a substantial improvement over an identical antenna made with normal metals.

  9. Superconducting microstrip antennas - An experimental comparison of two feeding methods

    NASA Technical Reports Server (NTRS)

    Richard, M. A.; Bhasin, Kul B.; Claspy, Paul C.

    1993-01-01

    The recent discovery of high-temperature superconductors (HTSs) has generated a substantial amount of interest in microstrip antenna applications. However, the high permittivity of substrates compatible with HTS causes difficulty in feeding such antennas because of the high patch edge impedance. Two methods for feeding HTS microstrip antennas at K- and Ka-band are examined. Superconducting microstrip antennas that are directly coupled and gap-coupled to a microstrip transmission line have been designed and fabricated on lanthanum aluminate substrates using Y-Ba-Cu-O superconducting thin films. Measurements from these antennas, including input impedance, bandwidth, efficiency, and patterns, are presented and compared with published models. The measured results demonstrate that usable antennas can be constructed using either of these architectures, although the antennas suffer from narrow bandwidths. In each case, the HTS antenna shows a substantial improvement over an identical antenna made with normal metals.

  10. Superconducting Microstrip Antennas: An Experimental Comparison of Two Feeding Methods

    NASA Technical Reports Server (NTRS)

    Richard, Mark A.; Claspy, Paul C.; Bhasin, Kul B.

    1993-01-01

    The recent discovery of high-temperature superconductors (HTSs) has generated a substantial amount of interest in microstrip antenna applications. However, the high permittivity of substrates compatible with HTS causes difficulty in feeding such antennas because of the high patch edge impedance. Two methods for feeding HTS microstrip antennas at K- and Ka-band are examined. Superconducting microstrip antennas that are directly coupled and gas-coupled to a microstrip transmission line have been designed and fabricated on lanthanum aluminate substrates using Y-Ba-Cu-O superconducting thin films. Measurements from these antennas, including input impedance, bandwidth, efficiency, and patterns, are presented and compared with published models. The measured results demonstrate that usable antennas can be constructed using either of these architectures, although the antennas suffer from narrow bandwidths. In each case, the HTS antenna shows a substantial improvement over an identical antenna made with normal metals

  11. Superconducting microstrip antennas: An experimental comparison of two feeding methods

    SciTech Connect

    Richard, M.A.; Claspy, P.C. ); Bhasin, K.B. . Lewis Research Center)

    1993-07-01

    The recent discovery of high-temperature superconductors (HTS's) has generated a substantial amount of interest in microstrip antenna applications. However, the high permittivity of substrates compatible with HTS causes difficulty in feeding such antennas because of the high patch edge impedance. In this paper, two methods for feeding HTS microstrip antennas at K and Ka-band are examined. Superconducting microstrip antennas that are directly coupled and gap-coupled to a microstrip transmission line have been designed and fabricated on lanthanum aluminate substrates using Y-Ba-Cu-O superconducting thin films. Measurements from these antennas, including input impedance, bandwidth, efficiency, and patterns, are presented and compared with published models. The measured results demonstrate that usable antennas can be constructed using either of these architectures, although the antennas suffer from narrow bandwidths. In each case, the HTS antenna shows a substantial improvement over an identical antenna made with normal metals.

  12. E-Textile Antennas for Space Environments

    NASA Technical Reports Server (NTRS)

    Kennedy, Timothy F.; Fink, Patrick W.; Chu, Andrew W.

    2007-01-01

    The ability to integrate antennas and other radio frequency (RF) devices into wearable systems is increasingly important as wireless voice, video, and data sources become ubiquitous. Consumer applications including mobile computing, communications, and entertainment, as well as military and space applications for integration of biotelemetry, detailed tracking information and status of handheld tools, devices and on-body inventories are driving forces for research into wearable antennas and other e-textile devices. Operational conditions for military and space applications of wireless systems are often such that antennas are a limiting factor in wireless performance. The changing antenna platform, i.e. the dynamic wearer, can detune and alter the radiation characteristics of e-textile antennas, making antenna element selection and design challenging. Antenna designs and systems that offer moderate bandwidth, perform well with flexure, and are electronically reconfigurable are ideally suited to wearable applications. Several antennas, shown in Figure 1, have been created using a NASA-developed process for e-textiles that show promise in being integrated into a robust wireless system for space-based applications. Preliminary characterization of the antennas with flexure indicates that antenna performance can be maintained, and that a combination of antenna design and placement are useful in creating robust designs. Additionally, through utilization of modern smart antenna techniques, even greater flexibility can be achieved since antenna performance can be adjusted in real-time to compensate for the antenna s changing environment.

  13. Patch antenna terahertz photodetectors

    SciTech Connect

    Palaferri, D.; Todorov, Y. Chen, Y. N.; Madeo, J.; Vasanelli, A.; Sirtori, C.; Li, L. H.; Davies, A. G.; Linfield, E. H.

    2015-04-20

    We report on the implementation of 5 THz quantum well photodetector exploiting a patch antenna cavity array. The benefit of our plasmonic architecture on the detector performance is assessed by comparing it with detectors made using the same quantum well absorbing region, but processed into a standard 45° polished facet mesa. Our results demonstrate a clear improvement in responsivity, polarization insensitivity, and background limited performance. Peak detectivities in excess of 5 × 10{sup 12} cmHz{sup 1/2}/W have been obtained, a value comparable with that of the best cryogenic cooled bolometers.

  14. Antenna Design Considerations for the Advanced Extravehicular Mobility Unit

    NASA Technical Reports Server (NTRS)

    Bakula, Casey J.; Theofylaktos, Onoufrios

    2015-01-01

    NASA is designing an Advanced Extravehicular Mobility Unit (AEMU)to support future manned missions beyond low-Earth orbit (LEO). A key component of the AEMU is the communications assembly that allows for the wireless transfer of voice, video, and suit telemetry. The Extravehicular Mobility Unit (EMU) currently used on the International Space Station (ISS) contains a radio system with a single omni-directional resonant cavity antenna operating slightly above 400 MHz capable of transmitting and receiving data at a rate of about 125 kbps. Recent wireless communications architectures are calling for the inclusion of commercial wireless standards such as 802.11 that operate in higher frequency bands at much higher data rates. The current AEMU radio design supports a 400 MHz band for low-rate mission-critical data and a high-rate band based on commercial wireless local area network (WLAN) technology to support video, communication with non-extravehicular activity (EVA) assets such as wireless sensors and robotic assistants, and a redundant path for mission-critical EVA data. This paper recommends the replacement of the existing EMU antenna with a new antenna that maintains the performance characteristics of the current antenna but with lower weight and volume footprints. NASA has funded several firms to develop such an antenna over the past few years, and the most promising designs are variations on the basic patch antenna. This antenna technology at UHF is considered by the authors to be mature and ready for infusion into NASA AEMU technology development programs.

  15. Mission Architecture Study Results for a Space-Based Gravitational-Wave Observatory (SGO)

    NASA Astrophysics Data System (ADS)

    Livas, Jeffrey C.; SGO Mission Concept Development Team

    2013-01-01

    The low-frequency band (0.0001 - 1 Hz) of the gravitational wave spectrum has a rich collection of astrophysical sources, and the Laser Interferometer Space Antenna (LISA) concept has been the key mission to cover this science for over twenty years. Although highly ranked in the 2010 Decadal Survey for the spectacular science return, tight budgets have forced NASA to consider a reformulation of the LISA mission concept at a lower cost point, even if at the expense of some of the science. We report the results of a mission architecture study that considered various options according to cost, risk, technical readiness, and the ability to address the Decadal-endorsed science goals.

  16. New concept of aging care architecture landscape design based on sustainable development

    NASA Astrophysics Data System (ADS)

    Xu, Ying

    2017-05-01

    As the aging problem becoming serious in China, Aging care is now one of the top issuer in front of all of us. Lots of private and public aging care architecture and facilities have been built. At present, we only pay attention to the architecture design and interior design scientific, ecological and sustainable design on aged care architecture landscape. Based on the social economy, population resources, mutual coordination and development of the environment, taking the elderly as the special group, this paper follows the principles of the sustainable development, conducts the comprehensive design planning of aged care landscape architecture and makes a deeper understanding and exploration through changing the form of architectural space, ecological landscape planting, new materials and technology, ecological energy utilization.

  17. An Enterprise Architecture Perspective to Electronic Health Record Based Care Governance.

    PubMed

    Motoc, Bogdan

    2017-01-01

    This paper proposes an Enterprise Architecture viewpoint of Electronic Health Record (EHR) based care governance. The improvements expected are derived from the collaboration framework and the clinical health model proposed as foundation for the concept of EHR.

  18. Investigations on the Influence of Antenna Near-field Effects and Satellite Obstruction on the Uncertainty of GNSS-based Distance Measurements

    NASA Astrophysics Data System (ADS)

    Zimmermann, Florian; Eling, Christian; Kuhlmann, Heiner

    2016-03-01

    Antenna near-field effects are one of the accuracy limiting factors on GNSS-based distance measurements. In order to analyse these influences, a measurement campaign at an EDM calibration baseline site with optimum GNSS conditions was performed. To vary the distance between the antenna mount and the absolutely calibrated antennas, spacers with different lengths were used. Due to the comparison of the resulting GNSS-based distance measurements to a reference solution, the influences of the antenna near-field could be analyzed. The standard deviations of the differences to the reference solution, i. e., 0.31 mm for the distance and 0.46 mm for the height component, indicate that equal spacer and antenna combinations at both stations lead to a very high accuracy level. In contrast, different spacer and antenna combinations decrease the accuracy level. Thus, an identical set-up at both antenna stations and the usage of individually calibrated antennas minimize the near-field effects during the double-differencing process. Hence, these aspects can be identified as a prerequisite for highly accurate GNSS-measurements. In addition to near-field effects, the influence of satellite obstructions is investigated. Four realistic shadowing scenarios are numerically simulated on the basis of the observations, which were collected in the optimum surrounding of the EDM calibration baseline site. The comparison to nominal values indicates that a shadowing leads only to a slight decreasing of the accuracy. Consequently, there is a strong suspicion that multipath effects and signal distortions seem to have a greater influence on the accuracy of GNSS-based distance measurements than the satellite constellation.

  19. Local Alignment Tool Based on Hadoop Framework and GPU Architecture

    PubMed Central

    Hung, Che-Lun; Hua, Guan-Jie

    2014-01-01

    With the rapid growth of next generation sequencing technologies, such as Slex, more and more data have been discovered and published. To analyze such huge data the computational performance is an important issue. Recently, many tools, such as SOAP, have been implemented on Hadoop and GPU parallel computing architectures. BLASTP is an important tool, implemented on GPU architectures, for biologists to compare protein sequences. To deal with the big biology data, it is hard to rely on single GPU. Therefore, we implement a distributed BLASTP by combining Hadoop and multi-GPUs. The experimental results present that the proposed method can improve the performance of BLASTP on single GPU, and also it can achieve high availability and fault tolerance. PMID:24955362

  20. Task-Based Crowd Simulation for Heterogeneous Architectures

    SciTech Connect

    Perez, Hugo; Rudomin, Isaac; Ayguade, Eduard

    2016-01-01

    Industry trends in the coming years imply the availability of cluster computing with hundreds to thousands of cores per chip, as well as the use of accelerators. Programming presents a challenge due to this heterogeneous architecture; thus, using novel programming models that facilitate this process is necessary. In this chapter, the case of simulation and visualization of crowds is presented. The authors analyze and compare the use of two programming models: OmpSs and CUDA. OmpSs allows to take advantage of all the resources available per node by combining the CPU and GPU while automatically taking care of memory management, scheduling, communications and synchronization. Experimental results obtained from Fermi, Kepler and Maxwell GPU architectures are presented, and the different modes used for visualizing the results are described, as well.

  1. Local alignment tool based on Hadoop framework and GPU architecture.

    PubMed

    Hung, Che-Lun; Hua, Guan-Jie

    2014-01-01

    With the rapid growth of next generation sequencing technologies, such as Slex, more and more data have been discovered and published. To analyze such huge data the computational performance is an important issue. Recently, many tools, such as SOAP, have been implemented on Hadoop and GPU parallel computing architectures. BLASTP is an important tool, implemented on GPU architectures, for biologists to compare protein sequences. To deal with the big biology data, it is hard to rely on single GPU. Therefore, we implement a distributed BLASTP by combining Hadoop and multi-GPUs. The experimental results present that the proposed method can improve the performance of BLASTP on single GPU, and also it can achieve high availability and fault tolerance.

  2. An Agent-Based Architecture for Generating Interactive Stories

    DTIC Science & Technology

    2002-09-01

    other characters, but also directly by the user. The interaction of the user impacts the development of the story, but not at discrete points in...without detailed planning. The underlying agent architecture centers around a mind-body design. The mind is the implementation of a social- psychological ...the plot level. By defining a set of plot events and computer events that will tell the story, interactive input by the user impacts the sequencing

  3. Formal Assurance for Cognitive Architecture Based Autonomous Agent

    NASA Technical Reports Server (NTRS)

    Bhattacharyya, Siddhartha; Eskridge, Thomas; Neogi, Natasha; Carvalho, Marco

    2017-01-01

    Autonomous systems are designed and deployed in different modeling paradigms. These environments focus on specific concepts in designing the system. We focus our effort in the use of cognitive architectures to design autonomous agents to collaborate with humans to accomplish tasks in a mission. Our research focuses on introducing formal assurance methods to verify the behavior of agents designed in Soar, by translating the agent to the formal verification environment Uppaal.

  4. Information-Theoretic Limits on Broadband Multi-Antenna Systems in the Presence of Mutual Coupling

    NASA Astrophysics Data System (ADS)

    Taluja, Pawandeep Singh

    2011-12-01

    Multiple-input, multiple-output (MIMO) systems have received considerable attention over the last decade due to their ability to provide high throughputs and mitigate multipath fading effects. While most of these benefits are obtained for ideal arrays with large separation between the antennas, practical devices are often constrained in physical dimensions. With smaller inter-element spacings, signal correlation and mutual coupling between the antennas start to degrade the system performance, thereby limiting the deployment of a large number of antennas. Various studies have proposed transceiver designs based on optimal matching networks to compensate for this loss. However, such networks are considered impractical due to their multiport structure and sensitivity to the RF bandwidth of the system. In this dissertation, we investigate two aspects of compact transceiver design. First, we consider simpler architectures that exploit coupling between the antennas, and second, we establish information-theoretic limits of broadband communication systems with closely-spaced antennas. We begin with a receiver model of a diversity antenna selection system and propose novel strategies that make use of inactive elements by virtue of mutual coupling. We then examine the limits on the matching efficiency of a single antenna system using broadband matching theory. Next, we present an extension to this theory for coupled MIMO systems to elucidate the impact of coupling on the RF bandwidth of the system, and derive optimal transceiver designs. Lastly, we summarize the main findings of this dissertation and suggest open problems for future work.

  5. Plasmonic polarization nano-splitter based on asymmetric optical slot antenna pairs.

    PubMed

    Chen, Bo; Yang, Jing; Hu, Chuang; Wang, Shaoxin; Wen, Qiuling; Zhang, Jiasen

    2016-11-01

    We propose and experimentally demonstrate a plasmonic polarization nano-splitter composed of asymmetric optical slot antenna pairs. Broadband polarization-controlled unidirectional surface plasmon polariton (SPP) launching and splitting are achieved experimentally using an asymmetric optical slot antenna pair array. Both transverse-electric and transverse-magnetic-polarized incident light is coupled to SPPs on the metal surface, but with opposite directions. The measured extinction ratio for the two opposite propagating directions is larger than 5 dB within a bandwidth of 160 nm and reaches up to ∼12  dB at an incident wavelength of 790 nm. This plasmonic polarization nano-splitter, together with the polarization-controlled unidirectional SPP coupler, may have promising applications in the nano-optics and integrated optical circuits.

  6. An e-consent-based shared EHR system architecture for integrated healthcare networks.

    PubMed

    Bergmann, Joachim; Bott, Oliver J; Pretschner, Dietrich P; Haux, Reinhold

    2007-01-01

    Virtual integration of distributed patient data promises advantages over a consolidated health record, but raises questions mainly about practicability and authorization concepts. Our work aims on specification and development of a virtual shared health record architecture using a patient-centred integration and authorization model. A literature survey summarizes considerations of current architectural approaches. Complemented by a methodical analysis in two regional settings, a formal architecture model was specified and implemented. Results presented in this paper are a survey of architectural approaches for shared health records and an architecture model for a virtual shared EHR, which combines a patient-centred integration policy with provider-oriented document management. An electronic consent system assures, that access to the shared record remains under control of the patient. A corresponding system prototype has been developed and is currently being introduced and evaluated in a regional setting. The proposed architecture is capable of partly replacing message-based communications. Operating highly available provider repositories for the virtual shared EHR requires advanced technology and probably means additional costs for care providers. Acceptance of the proposed architecture depends on transparently embedding document validation and digital signature into the work processes. The paradigm shift from paper-based messaging to a "pull model" needs further evaluation.

  7. OMEGA Norway Antenna System Characteristics: Modification and Validation Tests. Volume 3. Test Plan for Base Impedance.

    DTIC Science & Technology

    1978-05-08

    approximately 0.007 volts peak to peak. Remember this indication of maximum current for future use with Lissajous Figures. 6 Reduce the gain control of the...that connects the antenna to L. 3 Increase the gain control of the amplifier to obtain a small Lissajous figure on the oscilloscope. 4 Sweep the...current as indicated on the oscilloscope. c. Sweep the oscillator frequency up to the first point of resonance indicated by a Lissajous figure showing

  8. Proliferated Ground-Based, Long Wave, Transmitting Systems. Volume II. Antenna Subsystems.

    DTIC Science & Technology

    1980-03-31

    payload or lift (Lb) we observe that Lb = Bo - FL - Wbag (41) where: B = bouyancy of helium in air FL = free lift (10% recommended) Wbag = weight of... weight in excess of the bouyancy capability of the balloon. This is examined further in paragraph 5-3.2. Figure 26 also illustrates the concept of the...that, for electrically short antennas with electrically small ground planes, the total ground loss is minimally affected by the number (N) of ground

  9. Radar sensitivity and antenna scan pattern study for a satellite-based Radar Wind Sounder (RAWS)

    NASA Technical Reports Server (NTRS)

    Stuart, Michael A.

    1992-01-01

    Modeling global atmospheric circulations and forecasting the weather would improve greatly if worldwide information on winds aloft were available. Recognition of this led to the inclusion of the LAser Wind Sounder (LAWS) system to measure Doppler shifts from aerosols in the planned for Earth Observation System (EOS). However, gaps will exist in LAWS coverage where heavy clouds are present. The RAdar Wind Sensor (RAWS) is an instrument that could fill these gaps by measuring Doppler shifts from clouds and rain. Previous studies conducted at the University of Kansas show RAWS as a feasible instrument. This thesis pertains to the signal-to-noise ratio (SNR) sensitivity, transmit waveform, and limitations to the antenna scan pattern of the RAWS system. A dop-size distribution model is selected and applied to the radar range equation for the sensitivity analysis. Six frequencies are used in computing the SNR for several cloud types to determine the optimal transmit frequency. the results show the use of two frequencies, one higher (94 GHz) to obtain sensitivity for thinner cloud, and a lower frequency (24 GHz) to obtain sensitivity for thinner cloud, and a lower frequency (24 GHz) for better penetration in rain, provide ample SNR. The waveform design supports covariance estimation processing. This estimator eliminates the Doppler ambiguities compounded by the selection of such high transmit frequencies, while providing an estimate of the mean frequency. the unambiguous range and velocity computation shows them to be within acceptable limits. The design goal for the RAWS system is to limit the wind-speed error to less than 1 ms(exp -1). Due to linear dependence between vectors for a three-vector scan pattern, a reasonable wind-speed error is unattainable. Only the two-vector scan pattern falls within the wind-error limits for azimuth angles between 16 deg to 70 deg. However, this scan only allows two components of the wind to be determined. As a result, a technique is

  10. Innovative Escapement-Based Mechanism for Micro-Antenna Boom Deployment

    NASA Technical Reports Server (NTRS)

    Tokarz, Marta; Grygorczuk, Jerzy; Jarzynka, Stanislaw; Gut, Henryk

    2014-01-01

    This paper presents the prototype of a tubular boom antenna developed for the Polish BRITE-PL satellite by the Space Research Center of the Polish Academy of Sciences (CBK PAN). What is unique about our work is that we developed an original type of the tubular boom antenna deployment mechanism that can be used widely as a basic solution for compact electrical antennas, booms deploying sensitive instruments, ultra-light planetary manipulators etc. The invented electromagnetic driving unit provides a dual complementary action - it adds extra energy to the driving spring, making the system more reliable, and at the same time it moderates the deployment speed acting as a kind of damper. That distinguishing feature predetermines the mechanism to be applied wherever the dynamic nature of a spring drive introducing dangerous vibrations and inducing severe local stress in the structure needs to be mitigated. Moreover, the paper reveals a product unique in Europe - a miniature beryllium bronze tubular boom free of geometry and strain defects, which is essential for stiffness and fatigue resistance. Both the deployment mechanism and the technology of tubular boom manufacturing are protected by patent rights.

  11. A smart car for the surface shape measurement of large antenna based on laser tracker

    NASA Astrophysics Data System (ADS)

    Gu, Yonggang; Hu, Jing; Jin, Yi; Zhai, Chao

    2012-09-01

    The geometric accuracy of the surface shape of large antenna is an important indicator of antenna’s quality. Currently, high-precision measurement of large antenna surface shape can be performed in two ways: photogrammetry and laser tracker. Photogrammetry is a rapid method, but its accuracy is not enough good. Laser tracker can achieve high precision, but it is very inconvenient to move the reflector (target mirror) on the surface of the antenna by hand during the measurement. So, a smart car is designed to carry the reflector in this paper. The car, controlled by wireless, has a small weight and a strong ability for climbing, and there is a holding bracket gripping the reflector and controlling reflector rise up and drop down on the car. During the measurement of laser tracker, the laser beam between laser tracker and the reflector must not be interrupted, so two high-precision three-dimensional miniature electronic compasses, which can real-time monitor the relative angle between the holding bracket and the laser tracker’s head, are both equipped on the car and the head of laser tracker to achieve automatic alignment between reflector and laser beam. With the aid of the smart car, the measurement of laser tracker has the advantages of high precision and rapidity.

  12. A Low-Latency TDMA Scheduler for Multi-hop Cluster Based MANETs with Directional Antennas

    NASA Astrophysics Data System (ADS)

    Iannacone, Michael; Al-Mousa, Yamin; Martin, Nicholas; Shenoy, Nirmala; Fischer, John

    For Mobile Ad Hoc Network (MANET) applications which involve large propagation delays and/or directional antennas, a Time Division Multiple Access (TDMA) Medium Access Control (MAC) is a resource- and bandwidth-efficient solution. Meanwhile, clustering is a solution to the scalability and high mobility which is commonly required by MANETs. Here we develop a system which combines a TDMA MAC using directional antennas with the Multi-Meshed Tree (MMT) algorithm, which handles clustering and routing tasks. Some of the benefits of this combination include being able to synchronously schedule all intra-cluster routes as they are formed, being able to optimize the intra-cluster schedules for low latency, and being able to calculate these schedules with knowledge of only the intra-cluster topology, which is already maintained by MMT. We first analytically determine the end-to-end latency under various cases, and then confirm these results for several cases through OPNET simulation. Additionally, we note the high degree of slot re-use which is possible due to the use of directional antennas, which is demonstrated by the simulation results.

  13. Architectural and usability considerations in the development of a Web 2.0-based EHR.

    PubMed

    Senathirajah, Yalini; Bakken, Suzanne

    2009-01-01

    In our previous work, we described an electronic health record (EHR) architecture based on Web 2.0 principles. With this architecture, users in healthcare and public health can select, configure, share and control the information and interfaces they use by means of simple techniques such as "drag-and-drop" without the intervention of programmers. We extend this work by discussing architectural and usability considerations important for creating such an EHR. These include: new affordances facilitating element creation, responsiveness while using rich client-side interaction, consistency versus flexibility, security, workflow and evaluation.

  14. A Terahertz Detector Based on AlGaN/GaN High Electron Mobility Transistor with Bowtie Antennas

    NASA Astrophysics Data System (ADS)

    Sun, J. D.; Sun, Y. F.; Zhou, Y.; Zhang, Z. P.; Lin, W. K.; Zen, C. H.; Wu, D. M.; Zhang, B. S.; Qin, H.; Li, L. L.; Xu, W.

    2011-12-01

    We report on the characterization of room temperature terahertz (THz) based on a GaN/AlGaN high electron mobility transistor(HEMT) including bowtie antennas. Under THz irradiation around 1 THz, strong photocurrent is observed when the electron channel is strongly modulated by the gate voltage. Both experimental and simulation data support the validity of self-mixing model. The equivalent noise power (NEP) and responsivity are estimated to be 1nW/√Hz and 42 mA/W at 300 K, respectively.

  15. Uncooled antenna-coupled terahertz detectors with 22 μs response time based on BiSb/Sb thermocouples

    NASA Astrophysics Data System (ADS)

    Huhn, Anna K.; Spickermann, Gunnar; Ihring, Andreas; Schinkel, Uwe; Meyer, Hans-Georg; Haring Bolívar, Peter

    2013-03-01

    We report on fast terahertz detectors based on antenna-coupled BiSb/Sb thermoelements operating at room temperature. A response time of the thermocouples as low as 22 μs and a noise equivalent power of 170 pW/√Hz at 1 kHz modulation frequency is measured in air at room temperature. The integration capability of these mass producible devices enables large-scale detector arrays for real-time terahertz imaging applications. Due to the fast response time, multiplexing of the detectors can be used to reduce the required readout circuits.

  16. Predictive Algorithm For Aiming An Antenna

    NASA Technical Reports Server (NTRS)

    Gawronski, Wodek K.

    1993-01-01

    Method of computing control signals to aim antenna based on predictive control-and-estimation algorithm that takes advantage of control inputs. Conceived for controlling antenna in tracking spacecraft and celestial objects, near-future trajectories of which are known. Also useful in enhancing aiming performances of other antennas and instruments that track objects that move along fairly well known paths.

  17. Electrical performance verification methodology for large reflector antennas: based on the P-band SAR payload of the ESA BIOMASS candidate mission

    NASA Astrophysics Data System (ADS)

    Pivnenko, S.; Kim, O. S.; Nielsen, J. M.; Breinbjerg, O.; Pontoppidan, K.; Østergaard, A.; Lin, C. C.

    2013-12-01

    In this paper, an electrical performance verification methodology for large reflector antennas is proposed. The verification methodology was developed for the BIOMASS P-band (435 MHz) synthetic aperture radar (SAR), but can be applied to other large deployable or fixed reflector antennas for which the verification of the entire antenna or payload is impossible. The two-step methodology is based on accurate measurement of the feed structure characteristics, such as complex radiation pattern and radiation efficiency, with an appropriate measurement technique, and then accurate calculation of the radiation pattern and gain of the entire antenna including support and satellite structure with an appropriate computational software. A preliminary investigation of the proposed methodology was carried out by performing extensive simulations of different verification approaches. The experimental validation of the methodology included measurements of the prototype BIOMASS feed in several structural configurations with spherical, cylindrical, and planar near-field techniques. The measured characteristics for the feed structure were then used in the calculation of the radiation pattern and gain of the entire reflector antenna. The main emphasis of the work was on the assessment of the achievable pattern and gain uncertainty for the entire antenna and its compliance with the BIOMASS SAR requirements.

  18. Electrochemically Programmable Plasmonic Antennas.

    PubMed

    Dong, Shi; Zhang, Kai; Yu, Zhiping; Fan, Jonathan A

    2016-07-26

    Plasmonic antennas are building blocks in advanced nano-optical systems due to their ability to tailor optical response based on their geometry. We propose an electrochemical approach to program the optical properties of dipole antennas in a scalable, fast, and energy-efficient manner. These antennas comprise two arms, one serving as an anode and the other a cathode, separated by a solid electrolyte. As a voltage is applied between the antenna arms, a conductive filament either grows or dissolves within the electrolyte, modifying the antenna load. We probe the dynamics of stochastic filament formation and their effects on plasmonic mode programming using a combination of three-dimensional optical and electronic simulations. In particular, we identify device operation regimes in which the charge-transfer plasmon mode can be programmed to be "on" or "off." We also identify, unexpectedly, a strong correlation between DC filament resistance and charge-transfer plasmon mode frequency that is insensitive to the detailed filament morphology. We envision that the scalability of our electrochemical platform can generalize to large-area reconfigurable metamaterials and metasurfaces for on-chip and free-space applications.

  19. RRAM-based parallel computing architecture using k-nearest neighbor classification for pattern recognition.

    PubMed

    Jiang, Yuning; Kang, Jinfeng; Wang, Xinan

    2017-03-24

    Resistive switching memory (RRAM) is considered as one of the most promising devices for parallel computing solutions that may overcome the von Neumann bottleneck of today's electronic systems. However, the existing RRAM-based parallel computing architectures suffer from practical problems such as device variations and extra computing circuits. In this work, we propose a novel parallel computing architecture for pattern recognition by implementing k-nearest neighbor classification on metal-oxide RRAM crossbar arrays. Metal-oxide RRAM with gradual RESET behaviors is chosen as both the storage and computing components. The proposed architecture is tested by the MNIST database. High speed (~100 ns per example) and high recognition accuracy (97.05%) are obtained. The influence of several non-ideal device properties is also discussed, and it turns out that the proposed architecture shows great tolerance to device variations. This work paves a new way to achieve RRAM-based parallel computing hardware systems with high performance.

  20. Photonic Links for High-Performance Arraying of Antennas

    NASA Technical Reports Server (NTRS)

    Huang, Shouhua; Tjoelker, Robert

    2009-01-01

    An architecture for arraying microwave antennas in the next generation of NASA s Deep Space Network (DSN) involves the use of all photonic links between (1) the antennas in a given array and (2) a signal processing center. In this architecture, all affected parts at each antenna pedestal [except a front-end low-noise amplifier for the radio-frequency (RF) signal coming from the antenna and an optical transceiver to handle monitor and control (M/C) signals] would be passive optical parts

  1. A New Blind 2D-RAKE Receiver Based on CMA Criteria for Spread Spectrum Systems Suitable for Software Defined Radio Architecture

    NASA Astrophysics Data System (ADS)

    Takayama, Kei; Kamiya, Yukihiro; Fujii, Takeo; Suzuki, Yasuo

    Spread Spectrum (SS) has been widely used for various wireless systems such as cellular systems, wireless local area network (LAN) and so on. Using multiple antennas at the receiver, two-dimensional (2D) RAKE is realized over the time- and the space-domain. However, it should be noted that the 2D-RAKE receiver must detect the bit timing prior to the RAKE combining. In case of deep fading, it is often difficult to detect it due to low signal-to-noise power ratio (SNR). To solve this problem, we propose a new blind 2D-RAKE receiver based on the constant modulus algorithm (CMA). Since it does not need a priori bit timing detection, it is possible to compensate frequency selective fading even in very low SNR environments. The proposed method is particularly suitable for the software defined radio (SDR) architecture. The performance of the proposed method is investigated through computer simulations.

  2. DIRECTIONAL ANTENNA

    DOEpatents

    Bittner, B.J.

    1958-05-20

    A high-frequency directional antenna of the 360 d scaring type is described. The antenna has for its desirable features the reduction in both size and complexity of the mechanism for rotating the antenna through its scanning movement. These advantages result from the rotation of only the driven element, the reflector remaining stationary. The particular antenna structure comprises a refiector formed by a plurality of metallic slats arranged in the configuration of an annular cage having the shape of a zone of revolution. The slats are parallel to each other and are disposed at an angle of 45 d to the axis of the cage. A directional radiator is disposed inside the cage at an angle of 45 d to the axis of the cage in the same direction as the reflecting slats which it faces. As the radiator is rotated, the electromagnetic wave is reflected from the slats facing the radiator and thereafter passes through the cage on the opposite side, since these slats are not parallel with the E vector of the wave.

  3. Developing an Evaluation Method for Middleware-Based Software Architectures of Airborne Mission Systems

    DTIC Science & Technology

    2007-07-01

    documented using an architecture knowledge management tool also developed at NICTA. 31 DSTO-TR-2204 9. References [Ali- Babar & Gorton 2004] [Ali... Babar et al. 2005] [Allen et al. 2002] [Bachmann et al. 2003] [Barbacci et al. 1995] [Bass et al. 2003] [Basse/al. 2001] [Bengstsson et al. 2004...Boehm&In 1996] [CORBA 2006] [Clements et al. 2001] Ali- Babar , M. & Gorton, I. (2004) Comparison of Scenario-Based Software Architecture

  4. Graphene quantum dot antennas for high efficiency Förster resonance energy transfer based dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Subramanian, Alagesan; Pan, Zhenghui; Rong, Genlan; Li, Hongfei; Zhou, Lisha; Li, Wanfei; Qiu, Yongcai; Xu, Yijun; Hou, Yuan; Zheng, Zhaozhao; Zhang, Yuegang

    2017-03-01

    The light harvesting efficiency of an acceptor dye can be enhanced by judicious choice and/or design of donor materials in the Förster resonance energy transfer (FRET) based dye-sensitized solar cells (DSSCs). In this work, we explore graphene quantum dots (GQDs) as energy relay antennas for the high power conversion efficiency Ru-based N719 acceptor dyes. The absorption, emission, and time decay spectral results evidence the existence of the FRET, the radiative energy transfer (RET), and a synergistic interaction between GQDs and N719 dye. The FRET efficiency is measured to be 27%. The GQDs co-sensitized DSSC achieves an efficiency (ƞ) of 7.96% with a Jsc of 16.54 mAcm-2, which is 30% higher than that of a N719-based DSSC. GQDs also reduce the charge recombination, which results in an increased open-circuit voltage up to 770 mV. The incident photon-to-current conversion efficiency and UV-Vis absorption measurement reveal that the enhanced absorption of the GQDs antennas is responsible for the improved Jsc in the whole UV-Visible region, while the RET/FRET and the synergistic effect contribute to the significant increase of Jsc in the UV region.

  5. SiC: An Agent Based Architecture for Preventing and Detecting Attacks to Ubiquitous Databases

    NASA Astrophysics Data System (ADS)

    Pinzón, Cristian; de Paz, Yanira; Bajo, Javier; Abraham, Ajith; Corchado, Juan M.

    One of the main attacks to ubiquitous databases is the structure query language (SQL) injection attack, which causes severe damages both in the commercial aspect and in the user’s confidence. This chapter proposes the SiC architecture as a solution to the SQL injection attack problem. This is a hierarchical distributed multiagent architecture, which involves an entirely new approach with respect to existing architectures for the prevention and detection of SQL injections. SiC incorporates a kind of intelligent agent, which integrates a case-based reasoning system. This agent, which is the core of the architecture, allows the application of detection techniques based on anomalies as well as those based on patterns, providing a great degree of autonomy, flexibility, robustness and dynamic scalability. The characteristics of the multiagent system allow an architecture to detect attacks from different types of devices, regardless of the physical location. The architecture has been tested on a medical database, guaranteeing safe access from various devices such as PDAs and notebook computers.

  6. Rapid architecture alternative modeling (RAAM): A framework for capability-based analysis of system of systems architectures

    NASA Astrophysics Data System (ADS)

    Iacobucci, Joseph V.

    problem domain by establishing an effective means to communicate the semantics from the RAAM framework. These techniques make it possible to include diverse multi-metric models within the RAAM framework in addition to system and operational level trades. A canonical example was used to explore the uses of the methodology. The canonical example contains all of the features of a full system of systems architecture analysis study but uses fewer tasks and systems. Using RAAM with the canonical example it was possible to consider both system and operational level trades in the same analysis. Once the methodology had been tested with the canonical example, a Suppression of Enemy Air Defenses (SEAD) capability model was developed. Due to the sensitive nature of analyses on that subject, notional data was developed. The notional data has similar trends and properties to realistic Suppression of Enemy Air Defenses data. RAAM was shown to be traceable and provided a mechanism for a unified treatment of a variety of metrics. The SEAD capability model demonstrated lower computer runtimes and reduced model creation complexity as compared to methods currently in use. To determine the usefulness of the implementation of the methodology on current computing hardware, RAAM was tested with system of system architecture studies of different sizes. This was necessary since system of systems may be called upon to accomplish thousands of tasks. It has been clearly demonstrated that RAAM is able to enumerate and evaluate the types of large, complex design spaces usually encountered in capability based design, oftentimes providing the ability to efficiently search the entire decision space. The core algorithms for generation and evaluation of alternatives scale linearly with expected problem sizes. The SEAD capability model outputs prompted the discovery a new issue, the data storage and manipulation requirements for an analysis. Two strategies were developed to counter large data sizes, the use

  7. Galileo satellite antenna modeling

    NASA Astrophysics Data System (ADS)

    Steigenberger, Peter; Dach, Rolf; Prange, Lars; Montenbruck, Oliver

    2015-04-01

    The space segment of the European satellite navigation system Galileo currently consists of six satellites. Four of them belong to the first generation of In-Orbit Validation (IOV) satellites whereas the other two are Full Operational Capability (FOC) satellites. High-precision geodetic applications require detailed knowledge about the actual phase center of the satellite and receiver antenna. The deviation of this actual phase center from a well-defined reference point is described by phase center offsets (PCOs) and phase center variations (PCVs). Unfortunately, no public information is available about the Galileo satellite antenna PCOs and PCVs, neither for the IOV, nor the FOC satellites. Therefore, conventional values for the IOV satellite antenna PCOs have been adopted for the Multi-GNSS experiment (MGEX) of the International GNSS Service (IGS). The effect of the PCVs is currently neglected and no PCOs for the FOC satellites are available yet. To overcome this deficiency in GNSS observation modeling, satellite antenna PCOs and PCVs are estimated for the Galileo IOV satellites based on global GNSS tracking data of the MGEX network and additional stations of the legacy IGS network. Two completely independent solutions are computed with the Bernese and Napeos software packages. The PCO and PCV values of the individual satellites are analyzed and the availability of two different solutions allows for an accuracy assessment. The FOC satellites are built by a different manufacturer and are also equipped with another type of antenna panel compared to the IOV satellites. Signal transmission of the first FOC satellite has started in December 2014 and activation of the second satellite is expected for early 2015. Based on the available observations PCO estimates and, optionally PCVs of the FOC satellites will be presented as well. Finally, the impact of the new antenna model on the precision and accuracy of the Galileo orbit determination is analyzed.

  8. An expert-based model for selecting the most suitable substrate material type for antenna circuits

    NASA Astrophysics Data System (ADS)

    AL-Oqla, Faris M.; Omar, Amjad A.

    2015-06-01

    Quality and properties of microwave circuits depend on all the circuit components. One of these components is the substrate. The process of substrate material selection is a decision-making problem that involves multicriteria with objectives that are diverse and conflicting. The aim of this work was to select the most suitable substrate material type to be used in antennas in the microwave frequency range that gives best performance and reliability of the substrate. For this purpose, a model was built to ease the decision-making that includes hierarchical alternatives and criteria. The substrate material type options considered were limited to fiberglass-reinforced epoxy laminates (FR4 εr = 4.8), aluminium (III) oxide (alumina εr = 9.6), gallium arsenide III-V compound (GaAs εr = 12.8) and PTFE composites reinforced with glass microfibers (Duroid εr = 2.2-2.3). To assist in building the model and making decisions, the analytical hierarchy process (AHP) was used. The decision-making process revealed that alumina substrate material type was the most suitable choice for the antennas in the microwave frequency range that yields best performance and reliability. In addition, both the size of the circuit and the loss tangent of the substrates were found to be the most contributing subfactors in the antenna circuit specifications criterion. Experimental assessments were conducted utilising The Expert Choice™ software. The judgments were tested and found to be precise, consistent and justifiable, and the marginal inconsistency values were found to be very narrow. A sensitivity analysis was also presented to demonstrate the confidence in the drawn conclusions.

  9. A design of Si-based nanoplasmonic structure as an antenna and reception amplifier for visible light communication

    SciTech Connect

    Yan, J. H.; Lin, Z. Y.; Liu, P.; Yang, G. W.

    2014-10-21

    Visible light communication has been widely investigated due to its larger bandwidth and higher bit rate, and it can combine with the indoor illumination system that makes it more convenient to carry out. Receiving and processing the visible light signal on chip request for nanophotonics devices performing well. However, conventional optical device cannot be used for light-on-chip integration at subwavelength dimensions due to the diffraction limit. Herein, we propose a design of Si-based nanoplasmonic structure as an antenna and reception amplifier for visible light communication based on the interaction between Si nanoparticle and Au nanorod. This device integrates the unique scattering property of high-refractive index dielectric Si nanoparticles, whose scattering spectrum is dependent on the particle size, with the localized surface plasmon resonance of Au nanorod. We calculated the spectra collected by plane detector and near field distribution of nanostructure, and theoretically demonstrate that the proposed device can act as good receiver, amplifier and superlens during the visible light signal receiving and processing. Besides, unlike some other designs of nanoantenna devices focused less on how to detect the signals, our hybrid nanoantenna can realize the transfer between the scattering source and the detector effectively by Au nanorod waveguides. These findings suggest that the designed nanoplasmonic structure is expected to be used in on-chip nanophotonics as antenna, spectral splitter and demultiplexer for visible light communication.

  10. A design of Si-based nanoplasmonic structure as an antenna and reception amplifier for visible light communication

    NASA Astrophysics Data System (ADS)

    Yan, J. H.; Lin, Z. Y.; Liu, P.; Yang, G. W.

    2014-10-01

    Visible light communication has been widely investigated due to its larger bandwidth and higher bit rate, and it can combine with the indoor illumination system that makes it more convenient to carry out. Receiving and processing the visible light signal on chip request for nanophotonics devices performing well. However, conventional optical device cannot be used for light-on-chip integration at subwavelength dimensions due to the diffraction limit. Herein, we propose a design of Si-based nanoplasmonic structure as an antenna and reception amplifier for visible light communication based on the interaction between Si nanoparticle and Au nanorod. This device integrates the unique scattering property of high-refractive index dielectric Si nanoparticles, whose scattering spectrum is dependent on the particle size, with the localized surface plasmon resonance of Au nanorod. We calculated the spectra collected by plane detector and near field distribution of nanostructure, and theoretically demonstrate that the proposed device can act as good receiver, amplifier and superlens during the visible light signal receiving and processing. Besides, unlike some other designs of nanoantenna devices focused less on how to detect the signals, our hybrid nanoantenna can realize the transfer between the scattering source and the detector effectively by Au nanorod waveguides. These findings suggest that the designed nanoplasmonic structure is expected to be used in on-chip nanophotonics as antenna, spectral splitter and demultiplexer for visible light communication.

  11. An Architecture to Enable Future Sensor Webs

    NASA Technical Reports Server (NTRS)

    Mandl, Dan; Caffrey, Robert; Frye, Stu; Grosvenor, Sandra; Hess, Melissa; Chien, Steve; Sherwood, Rob; Davies, Ashley; Hayden, Sandra; Sweet, Adam

    2004-01-01

    A sensor web is a coherent set of distributed 'nodes', interconnected by a communications fabric, that collectively behave as a single dynamic observing system. A 'plug and play' mission architecture enables progressive mission autonomy and rapid assembly and thereby enables sensor webs. This viewgraph presentation addresses: Target mission messaging architecture; Strategy to establish architecture; Progressive autonomy with onboard sensor web; EO-1; Adaptive array antennas (smart antennas) for satellite ground stations.

  12. Radar based Ground Level Reconstruction Utilizing a Hypocycloid Antenna Positioning System

    NASA Astrophysics Data System (ADS)

    Baer, Christoph; Musch, Thomas

    2015-01-01

    In this contribution we introduce a novel radar positioning system. It makes use of a mathematical curve, called hypocycloid, for a slanting movement of the radar antenna. By means of a planetary gear, a ball, and a universal joint as well as a stepping motor, a two dimensional positioning is provided by a uniaxial drive shaft exclusively. The fundamental position calculation and different signal processing algorithms are presented. By means of an 80 GHz FMCW radar system we performed several measurements on objects with discrete heights as well as on objects with continuous surfaces. The results of these investigations are essential part of this contribution and are discussed in detail.

  13. Bit error rate testing of fiber optic data links for MMIC-based phased array antennas

    NASA Astrophysics Data System (ADS)

    Shalkhauser, K. A.; Kunath, R. R.; Daryoush, A. S.

    1990-06-01

    The measured bit-error-rate (BER) performance of a fiber optic data link to be used in satellite communications systems is presented and discussed. In the testing, the link was measured for its ability to carry high burst rate, serial-minimum shift keyed (SMSK) digital data similar to those used in actual space communications systems. The fiber optic data link, as part of a dual-segment injection-locked RF fiber optic link system, offers a means to distribute these signals to the many radiating elements of a phased array antenna. Test procedures, experimental arrangements, and test results are presented.

  14. Bit error rate testing of fiber optic data links for MMIC-based phased array antennas

    NASA Technical Reports Server (NTRS)

    Shalkhauser, K. A.; Kunath, R. R.; Daryoush, A. S.

    1990-01-01

    The measured bit-error-rate (BER) performance of a fiber optic data link to be used in satellite communications systems is presented and discussed. In the testing, the link was measured for its ability to carry high burst rate, serial-minimum shift keyed (SMSK) digital data similar to those used in actual space communications systems. The fiber optic data link, as part of a dual-segment injection-locked RF fiber optic link system, offers a means to distribute these signals to the many radiating elements of a phased array antenna. Test procedures, experimental arrangements, and test results are presented.

  15. A Low Cost VLSI Architecture for Spike Sorting Based on Feature Extraction with Peak Search

    PubMed Central

    Chang, Yuan-Jyun; Hwang, Wen-Jyi; Chen, Chih-Chang

    2016-01-01

    The goal of this paper is to present a novel VLSI architecture for spike sorting with high classification accuracy, low area costs and low power consumption. A novel feature extraction algorithm with low computational complexities is proposed for the design of the architecture. In the feature extraction algorithm, a spike is separated into two portions based on its peak value. The area of each portion is then used as a feature. The algorithm is simple to implement and less susceptible to noise interference. Based on the algorithm, a novel architecture capable of identifying peak values and computing spike areas concurrently is proposed. To further accelerate the computation, a spike can be divided into a number of segments for the local feature computation. The local features are subsequently merged with the global ones by a simple hardware circuit. The architecture can also be easily operated in conjunction with the circuits for commonly-used spike detection algorithms, such as the Non-linear Energy Operator (NEO). The architecture has been implemented by an Application-Specific Integrated Circuit (ASIC) with 90-nm technology. Comparisons to the existing works show that the proposed architecture is well suited for real-time multi-channel spike detection and feature extraction requiring low hardware area costs, low power consumption and high classification accuracy. PMID:27941631

  16. A Low Cost VLSI Architecture for Spike Sorting Based on Feature Extraction with Peak Search.

    PubMed

    Chang, Yuan-Jyun; Hwang, Wen-Jyi; Chen, Chih-Chang

    2016-12-07

    The goal of this paper is to present a novel VLSI architecture for spike sorting with high classification accuracy, low area costs and low power consumption. A novel feature extraction algorithm with low computational complexities is proposed for the design of the architecture. In the feature extraction algorithm, a spike is separated into two portions based on its peak value. The area of each portion is then used as a feature. The algorithm is simple to implement and less susceptible to noise interference. Based on the algorithm, a novel architecture capable of identifying peak values and computing spike areas concurrently is proposed. To further accelerate the computation, a spike can be divided into a number of segments for the local feature computation. The local features are subsequently merged with the global ones by a simple hardware circuit. The architecture can also be easily operated in conjunction with the circuits for commonly-used spike detection algorithms, such as the Non-linear Energy Operator (NEO). The architecture has been implemented by an Application-Specific Integrated Circuit (ASIC) with 90-nm technology. Comparisons to the existing works show that the proposed architecture is well suited for real-time multi-channel spike detection and feature extraction requiring low hardware area costs, low power consumption and high classification accuracy.

  17. A comparative analysis of loop heat pipe based thermal architectures for spacecraft thermal control

    NASA Technical Reports Server (NTRS)

    Pauken, Mike; Birur, Gaj

    2004-01-01

    Loop Heat Pipes (LHP) have gained acceptance as a viable means of heat transport in many spacecraft in recent years. However, applications using LHP technology tend to only remove waste heat from a single component to an external radiator. Removing heat from multiple components has been done by using multiple LHPs. This paper discusses the development and implementation of a Loop Heat Pipe based thermal architecture for spacecraft. In this architecture, a Loop Heat Pipe with multiple evaporators and condensers is described in which heat load sharing and thermal control of multiple components can be achieved. A key element in using a LHP thermal architecture is defining the need for such an architecture early in the spacecraft design process. This paper describes an example in which a LHP based thermal architecture can be used and how such a system can have advantages in weight, cost and reliability over other kinds of distributed thermal control systems. The example used in this paper focuses on a Mars Rover Thermal Architecture. However, the principles described here are applicable to Earth orbiting spacecraft as well.

  18. Architectural mechanisms for dynamic changes of behavior selection strategies in behavior-based systems.

    PubMed

    Scheutz, Matthias; Andronache, Virgil

    2004-12-01

    Behavior selection is typically a "built-in" feature of behavior-based architectures and hence, not amenable to change. There are, however, circumstances where changing behavior selection strategies is useful and can lead to better performance. In this paper, we demonstrate that such dynamic changes of behavior selection mechanisms are beneficial in several circumstances. We first categorize existing behavior selection mechanisms along three dimensions and then discuss seven possible circumstances where dynamically switching among them can be beneficial. Using the agent architecture framework activation, priority, observer, and component (APOC), we show how instances of all (nonempty) categories can be captured and how additional architectural mechanisms can be added to allow for dynamic switching among them. In particular, we propose a generic architecture for dynamic behavior selection, which can integrate existing behavior selection mechanisms in a unified way. Based on this generic architecture, we then verify that dynamic behavior selection is beneficial in the seven cases by defining architectures for simulated and robotic agents and performing experiments with them. The quantitative and qualitative analyzes of the results obtained from extensive simulation studies and experimental runs with robots verify the utility of the proposed mechanisms.

  19. On the safety assessment of human exposure in the proximity of cellular communications base-station antennas at 900, 1800 and 2170 MHz.

    PubMed

    Martínez-Búrdalo, M; Martín, A; Anguiano, M; Villar, R

    2005-09-07

    In this work, the procedures for safety assessment in the close proximity of cellular communications base-station antennas at three different frequencies (900, 1800 and 2170 MHz) are analysed. For each operating frequency, we have obtained and compared the distances to the antenna from the exposure places where electromagnetic fields are below reference levels and the distances where the specific absorption rate (SAR) values in an exposed person are below the basic restrictions, according to the European safety guidelines. A high-resolution human body model has been located, in front of each base-station antenna as a worst case, at different distances, to compute whole body averaged SAR and maximum 10 g averaged SAR inside the exposed body. The finite-difference time-domain method has been used for both electromagnetic fields and SAR calculations. This paper shows that, for antenna-body distances in the near zone of the antenna, the fact that averaged field values be below the reference levels could, at certain frequencies, not guarantee guidelines compliance based on basic restrictions.

  20. 41 CFR 102-79.80 - May Executive agencies assess fees for antenna placements against telecommunication service...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... assess fees for antenna placements against telecommunication service providers for antenna site outleases... antenna placements against telecommunication service providers for antenna site outleases on major..., upon approval from GSA, may charge fees based on market value to telecommunication service...

  1. 41 CFR 102-79.80 - May Executive agencies assess fees for antenna placements against telecommunication service...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... assess fees for antenna placements against telecommunication service providers for antenna site outleases... antenna placements against telecommunication service providers for antenna site outleases on major..., upon approval from GSA, may charge fees based on market value to telecommunication service...

  2. 41 CFR 102-79.80 - May Executive agencies assess fees for antenna placements against telecommunication service...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... assess fees for antenna placements against telecommunication service providers for antenna site outleases... antenna placements against telecommunication service providers for antenna site outleases on major..., upon approval from GSA, may charge fees based on market value to telecommunication service...

  3. 41 CFR 102-79.80 - May Executive agencies assess fees for antenna placements against telecommunication service...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... assess fees for antenna placements against telecommunication service providers for antenna site outleases... antenna placements against telecommunication service providers for antenna site outleases on major..., upon approval from GSA, may charge fees based on market value to telecommunication service...

  4. 41 CFR 102-79.80 - May Executive agencies assess fees for antenna placements against telecommunication service...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... assess fees for antenna placements against telecommunication service providers for antenna site outleases... antenna placements against telecommunication service providers for antenna site outleases on major..., upon approval from GSA, may charge fees based on market value to telecommunication service...

  5. Design and Implementation of Hybrid MAC-Based Robust Architecture for Wireless Sensor Network

    NASA Astrophysics Data System (ADS)

    Shon, Taeshik; Kim, Eui-Jik; in, Jeongsik; Park, Yongsuk

    In this letter, we propose an energy efficient hybrid architecture, the Hybrid MAC-based Robust Architecture (HMR), for wireless sensor networks focusing on MAC layer's scheduling and adaptive security suite as a security sub layer. A hybrid MAC layer with TDMA and CSMA scheduling is designed to prolong network life time, and the multi-channel TDMA based active/sleep scheduling is presented. We also present the security related functionalities needed to employ a flexible security suite to packets dynamically. Implementation and testbed of the proposed framework based on IEEE 802.15.4 are shown as well.

  6. An optimized, universal hardware-based adaptive correlation receiver architecture

    NASA Astrophysics Data System (ADS)

    Zhu, Zaidi; Suarez, Hernan; Zhang, Yan; Wang, Shang

    2014-05-01

    The traditional radar RF transceivers, similar to communication transceivers, have the basic elements such as baseband waveform processing, IF/RF up-down conversion, transmitter power circuits, receiver front-ends, and antennas, which are shown in the upper half of Figure 1. For modern radars with diversified and sophisticated waveforms, we can frequently observe that the transceiver behaviors, especially nonlinear behaviors, are depending on the waveform amplitudes, frequency contents and instantaneous phases. Usually, it is a troublesome process to tune an RF transceiver to optimum when different waveforms are used. Another issue arises from the interference caused by the waveforms - for example, the range side-lobe (RSL) caused by the waveforms, once the signals pass through the entire transceiver chain, may be further increased due to distortions. This study is inspired by the two existing solutions from commercial communication industry, digital pre-distortion (DPD) and adaptive channel estimation and Interference Mitigation (AIM), while combining these technologies into a single chip or board that can be inserted into the existing transceiver system. This device is then named RF Transceiver Optimizer (RTO). The lower half of Figure 1 shows the basic element of RTO. With RTO, the digital baseband processing does not need to take into account the transceiver performance with diversified waveforms, such as the transmitter efficiency and chain distortion (and the intermodulation products caused by distortions). Neither does it need to concern the pulse compression (or correlation receiver) process and the related mitigation. The focus is simply the information about the ground truth carried by the main peak of correlation receiver outputs. RTO can be considered as an extension of the existing calibration process, while it has the benefits of automatic, adaptive and universal. Currently, the main techniques to implement the RTO are the digital pre- or -post

  7. Superluminal antenna

    DOEpatents

    Singleton, John; Earley, Lawrence M.; Krawczyk, Frank L.; Potter, James M.; Romero, William P.; Wang, Zhi-Fu

    2017-03-28

    A superluminal antenna element integrates a balun element to better impedance match an input cable or waveguide to a dielectric radiator element, thus preventing stray reflections and consequent undesirable radiation. For example, a dielectric housing material can be used that has a cutout area. A cable can extend into the cutout area. A triangular conductor can function as an impedance transition. An additional cylindrical element functions as a sleeve balun to better impedance match the radiator element to the cable.

  8. Effects of space environment on space-based radar phased-array antenna: Status and preliminary observations

    NASA Technical Reports Server (NTRS)

    Whiteside, J. B.; Giangano, D.; Heuer, R. L.; Kamykowski, E.; Kesselman, M.; Rooney, W.; Schulte, R.; Stauber, Michael C.

    1991-01-01

    The overall objective is to evaluate the effect of the space environment on Kapton films considered for the Grumman space based radar (SBR) phased-array antenna. The most striking result is the overall good condition of the Kapton antenna planes and Kapton tensile specimens. This is largely attributable to the orientation of the Kapton (parallel and flush on the space end) and the stability of the LDEF in orbit. Results on elongation and mechanical properties of the plain and fiberglass reinforced Kapton will be described. Stress-dependent permanent deformation and some reductions in strain to failure were observed. Physical property testing of the materials is in progress. Electronic data acquisition and memory systems appeared to operate correctly, but functional tests were not yet performed. An evaluation of the high voltage-plasma interaction data is underway. Some minor systems anomalies (e.g., fastener sheared during removal, strong odor inside electronics container) were noted. Other observations such as radiation, contamination, impacts, and orientation features of atomic oxygen erosion are reported.

  9. Artificial magnetic conductor-based circularly polarized crossed-dipole antennas: 1. AMC structure with grounding pins

    NASA Astrophysics Data System (ADS)

    Ta, Son Xuat; Park, Ikmo

    2017-05-01

    In this paper, we analyze low-profile circularly polarized (CP) antennas comprising a crossed-dipole radiator on finite artificial magnetic conductor (AMC) surfaces. The crossed dipole is fed by a pair of vacant-quarter printed rings to produce CP radiation. The AMC structure consists of a lattice of square metal plates on a grounded dielectric substrate with connecting pins between the patches and the ground plane. In this paper, we focus on the excitation of surface waves propagating on the finite-sized AMC surface, which generates extra resonances and CP radiations for the radiation structures. We predict the surface-wave resonances using a cavity model. In this model, the finite-sized AMC structure is considered as a waveguide resonator. We verify the predicted results computationally using the finite element method-based full-wave electromagnetic solver Ansoft high-frequency structure simulator. The results show that these extra resonances and corresponding CP radiations can be used to broaden the impedance matching and axial ratio bandwidths of the antennas, respectively.

  10. Performance analysis for IEEE 802.11 distributed coordination function in radio-over-fiber-based distributed antenna systems.

    PubMed

    Fan, Yuting; Li, Jianqiang; Xu, Kun; Chen, Hao; Lu, Xun; Dai, Yitang; Yin, Feifei; Ji, Yuefeng; Lin, Jintong

    2013-09-09

    In this paper, we analyze the performance of IEEE 802.11 distributed coordination function in simulcast radio-over-fiber-based distributed antenna systems (RoF-DASs) where multiple remote antenna units (RAUs) are connected to one wireless local-area network (WLAN) access point (AP) with different-length fiber links. We also present an analytical model to evaluate the throughput of the systems in the presence of both the inter-RAU hidden-node problem and fiber-length difference effect. In the model, the unequal delay induced by different fiber length is involved both in the backoff stage and in the calculation of Ts and Tc, which are the period of time when the channel is sensed busy due to a successful transmission or a collision. The throughput performances of WLAN-RoF-DAS in both basic access and request to send/clear to send (RTS/CTS) exchange modes are evaluated with the help of the derived model.

  11. From rectangle-shaped to square-shaped antennas based on graphene: T-shaped, Cross-shaped and Rectangle-shaped Structure Transitions

    NASA Astrophysics Data System (ADS)

    Rodriguez-Toro, Victor A.; Gabrielli, Lucas H.; Fragnito, Hugo; Hernandez-Figueroa, Hugo E.

    2014-03-01

    The absorbing cross section (ACS) for graphene-based terahertz antennas is calculated for different shapes. All structures are wide enough so that edge effects can be neglected. A general Kubo form considering only intraband transitions approximates the material conductivity for graphene, while its relative permittivity and permeability are kept at 1. Being valid in a frequency range between 0.5THz and 4THz, we use this model to find the frequency at which the maximum ACS is reached for each of the analyzed antenna shapes. In this exploration, we numerically study the performance of arbitrary rectangular, T- and cross-shaped antennas. These results can also be useful for the design of complex graphene-based metamaterials operating in the terahertz range.

  12. Circuital characteristics and radiation properties of an UWB electric-magnetic planar antenna for Ku-band applications

    NASA Astrophysics Data System (ADS)

    Haider, N.; Caratelli, D.; Yarovoy, A. G.

    2013-01-01

    A planar, directive antenna with large fractional bandwidth is introduced in this paper. A detailed discussion on the proposed antenna topology and its architecture is reported. The proposed element is a combination of a patch and a loop radiator. A proper combination of the electric field radiator (patch) with a magnetic field radiator (loop around the patch) is exploited for expanding the operational bandwidth. A parametric study is presented to investigate the effect of the antenna geometrical parameters on its performance. A general and computationally efficient procedure for extracting the antenna equivalent circuit is described and used to achieve a meaningful circuit theory-based insight into the characteristics of the radiating structure. The theoretical and experimental results are compared, and it is demonstrated that the element features over 100% fractional bandwidth, good impedance matching, and unidirectional and stable radiation patterns.

  13. A component-based, distributed object services architecture for a clinical workstation.

    PubMed Central

    Chueh, H. C.; Raila, W. F.; Pappas, J. J.; Ford, M.; Zatsman, P.; Tu, J.; Barnett, G. O.

    1996-01-01

    Attention to an architectural framework in the development of clinical applications can promote reusability of both legacy systems as well as newly designed software. We describe one approach to an architecture for a clinical workstation application which is based on a critical middle tier of distributed object-oriented services. This tier of network-based services provides flexibility in the creation of both the user interface and the database tiers. We developed a clinical workstation for ambulatory care using this architecture, defining a number of core services including those for vocabulary, patient index, documents, charting, security, and encounter management. These services can be implemented through proprietary or more standard distributed object interfaces such as CORBA and OLE. Services are accessed over the network by a collection of user interface components which can be mixed and matched to form a variety of interface styles. These services have also been reused with several applications based on World Wide Web browser interfaces. PMID:8947744

  14. A VLSI Architecture with Multiple Fast Store-Based Block Parallel Processing for Output Probability and Likelihood Score Computations in HMM-Based Isolated Word Recognition

    NASA Astrophysics Data System (ADS)

    Nakamura, Kazuhiro; Shimazaki, Ryo; Yamamoto, Masatoshi; Takagi, Kazuyoshi; Takagi, Naofumi

    This paper presents a memory-efficient VLSI architecture for output probability computations (OPCs) of continuous hidden Markov models (HMMs) and likelihood score computations (LSCs). These computations are the most time consuming part of HMM-based isolated word recognition systems. We demonstrate multiple fast store-based block parallel processing (MultipleFastStoreBPP) for OPCs and LSCs and present a VLSI architecture that supports it. Compared with conventional fast store-based block parallel processing (FastStoreBPP) and stream-based block parallel processing (StreamBPP) architectures, the proposed architecture requires fewer registers and less processing time. The processing elements (PEs) used in the FastStoreBPP and StreamBPP architectures are identical to those used in the MultipleFastStoreBPP architecture. From a VLSI architectural viewpoint, a comparison shows that the proposed architecture is an improvement over the others, through efficient use of PEs and registers for storing input feature vectors.

  15. Rule-based graph theory to enable exploration of the space system architecture design space

    NASA Astrophysics Data System (ADS)

    Arney, Dale Curtis

    network flow problems in the past, where nodes represent physical locations and edges represent the means by which information or vehicles travel between those locations. In space system architecting, expressing the physical locations (low-Earth orbit, low-lunar orbit, etc.) and steady states (interplanetary trajectory) as nodes and the different means of moving between the nodes (propulsive maneuvers, etc.) as edges formulates a mathematical representation of this design space. The selection of a given system architecture using graph theory entails defining the paths that the systems take through the space system architecture graph. A path through the graph is defined as a list of edges that are traversed, which in turn defines functions performed by the system. A structure to compactly represent this information is a matrix, called the system map, in which the column indices are associated with the systems that exist and row indices are associated with the edges, or functions, to which each system has access. Several contributions have been added to the state of the art in space system architecture analysis. The framework adds the capability to rapidly explore the design space without the need to limit trade options or the need for user interaction during the exploration process. The unique mathematical representation of a system architecture, through the use of the adjacency, incidence, and system map matrices, enables automated design space exploration using stochastic optimization processes. The innovative rule-based graph traversal algorithm ensures functional feasibility of each system architecture that is analyzed, and the automatic generation of the system hierarchy eliminates the need for the user to manually determine the relationships between systems during or before the design space exploration process. Finally, the rapid evaluation of system architectures for various mission types enables analysis of the system architecture design space for multiple

  16. Determination of safety distance limits for a human near a cellular base station antenna, adopting the IEEE standard or ICNIRP guidelines.

    PubMed

    Cooper, Justin; Marx, Bernd; Buhl, Johannes; Hombach, Volker

    2002-09-01

    This paper investigates the minimum distance for a human body in the near field of a cellular telephone base station antenna for which there is compliance with the IEEE or ICNIRP threshold values for radio frequency electromagnetic energy absorption in the human body. First, local maximum specific absorption rates (SARs), measured and averaged over volumes equivalent to 1 and to 10 g tissue within the trunk region of a physical, liquid filled shell phantom facing and irradiated by a typical GSM 900 base station antenna, were compared to corresponding calculated SAR values. The calculation used a homogeneous Visible Human body model in front of a simulated base station antenna of the same type. Both real and simulated base station antennas operated at 935 MHz. Antenna-body distances were between 1 and 65 cm. The agreement between measurements and calculations was excellent. This gave confidence in the subsequent calculated SAR values for the heterogeneous Visible Human model, for which each tissue was assigned the currently accepted values for permittivity and conductivity at 935 MHz. Calculated SAR values within the trunk of the body were found to be about double those for the homogeneous case. When the IEEE standard and the ICNIRP guidelines are both to be complied with, the local SAR averaged over 1 g tissue was found to be the determining parameter. Emitted power values from the antenna that produced the maximum SAR value over 1 g specified in the IEEE standard at the base station are less than those needed to reach the ICNIRP threshold specified for the local SAR averaged over 10 g. For the GSM base station antenna investigated here operating at 935 MHz with 40 W emitted power, the model indicates that the human body should not be closer to the antenna than 18 cm for controlled environment exposure, or about 95 cm for uncontrolled environment exposure. These safe distance limits are for SARs averaged over 1 g tissue. The corresponding safety distance limits

  17. On the significance of the anchoring group in the design of antenna materials based on phthalocyanine stopcocks and zeolite L.

    PubMed

    López-Duarte, Ismael; Dieu, Le-Quyenh; Dolamic, Igor; Martínez-Díaz, M Victoria; Torres, Tomás; Calzaferri, Gion; Brühwiler, Dominik

    2011-02-07

    The synthesis of stopcocks based on zinc phthalocyanine for selective adsorption at the channel entrances of zeolite L is reported. The introduction of either an inert SiMe₃ moiety, an imidazolium cation or a reactive isothiocyanate (NCS) group allows attachment to the channel entrances of zeolite L through van der Waals interactions, electrostatic interactions, or covalent binding, respectively. Stopcocks that rely on van-der-Waals-driven adsorption require careful selection of the solvent used for the deposition onto the zeolite surface to avoid a nonspecific distribution of the molecules. Regarding the design of photonic antenna systems, a stopcock with a cationic tail was found to be the most convenient, based on the observation that efficient energy transfer from molecules located in the zeolite nanochannels is more readily obtained than in the other cases.

  18. [Wearable Medical Devices' MCU Selection Analysis Based on the ARM Cortex-MO+ Architecture].

    PubMed

    Wu, Zaoquan; Liu, Mengxing; Qin, Liping; Ye, Shuming; Chen, Hang

    2015-03-01

    According to the characteristics of low cost, high performance, high integration and long battery life of wearable medical devices, the mainstream low-power microcontroller(MCU) series were compared, and came to the conclusion that the MCU series based on ARM Cortex-M0+ architecture were suitable for the development of wearable medical devices. In aspects of power consumption, operational performance, integrated peripherals and cost, the MCU series based on Cortex-M0+ architecture of primary semiconductor companies were compared, aimed at providing the guides of MCU selection for wearable medical devices.

  19. The research of service provision based on service-oriented architecture for NGN

    NASA Astrophysics Data System (ADS)

    Jie, Yin; Nian, Zhou; Qian, Mao

    2007-11-01

    Service convergence is an important characteristic of NGN(Next Generation Networking). How to integrate the service capabilities of telecommunication network and Internet. At first, this article puts forward the concepts and characteristics of SOA (Service-Oriented Architecture) and Web Service, then discusses relationship between them. Secondly, combined with five kinds of Service Provision in NGN, A service platform architecture design of NGN and a service development mode based on SOA are brought up. At last, a specific example is analyzed with BPEL (Business Process Execution Language) in order to describe service development flow based on SOA for NGN.

  20. A framework for semantic interoperability in healthcare: a service oriented architecture based on health informatics standards.

    PubMed

    Ryan, Amanda; Eklund, Peter

    2008-01-01

    Healthcare information is composed of many types of varying and heterogeneous data. Semantic interoperability in healthcare is especially important when all these different types of data need to interact. Presented in this paper is a solution to interoperability in healthcare based on a standards-based middleware software architecture used in enterprise solutions. This architecture has been translated into the healthcare domain using a messaging and modeling standard which upholds the ideals of the Semantic Web (HL7 V3) combined with a well-known standard terminology of clinical terms (SNOMED CT).

  1. 802.11ac WLAN MIMO radio-over-fiber distributed antenna system for in-building networks based on multicore fiber

    NASA Astrophysics Data System (ADS)

    Morant, Maria; Llorente, Roberto

    2017-01-01

    In this work we propose and evaluate experimentally the performance of IEEE 802.11ac WLAN standard signals in radio-over-fiber (RoF) distributed-antenna systems based on multicore fiber (MCF) for in-building WLAN connectivity. The RoF performance of WLAN signals with different bandwidth is investigated considering up to IEEE 802.11ac maximum of 160 MHz per user. We evaluate experimentally the performance of WLAN signals employing different modulation and coding schemes achieving bitrates from 78 Mbps to 1404 Mbps per user in distances up to 300 m in a 4-core MCF. The performance of the wireless standard multiple-input multiple-output (MIMO) processing algorithms included in WLAN signals applied to the RoF transmission in MCF optical systems is also evaluated. The impact on the quality of the signal from one of the cores in the MIMO processing is investigated and compared with the results achieved with single-input single-output (SISO) transmission in each core. We measured the error vector magnitude (EVM) and the OFDM data burst information of the received WLAN signals after RoF transmission for different distributed-antenna systems with uni- and bi-directional MCF communication. Finally, we compare the received EVM of a single-antenna system (SISO arrangement) with WLAN systems using two antennas (2×2 MIMO) and four antennas (4×4 MIMO).

  2. High power telecommunication-compatible photoconductive terahertz emitters based on plasmonic nano-antenna arrays

    NASA Astrophysics Data System (ADS)

    Yardimci, Nezih Tolga; Lu, Hong; Jarrahi, Mona

    2016-11-01

    We present a high-power and broadband photoconductive terahertz emitter operating at telecommunication optical wavelengths, at which compact and high-performance fiber lasers are commercially available. The presented terahertz emitter utilizes an ErAs:InGaAs substrate to achieve high resistivity and short carrier lifetime characteristics required for robust operation at telecommunication optical wavelengths. It also uses a two-dimensional array of plasmonic nano-antennas to offer significantly higher optical-to-terahertz conversion efficiencies compared to the conventional photoconductive emitters, while maintaining broad operation bandwidths. We experimentally demonstrate pulsed terahertz radiation over 0.1-5 THz frequency range with the power levels as high as 300 μW. This is the highest-reported terahertz radiation power from a photoconductive emitter operating at telecommunication optical wavelengths.

  3. High power telecommunication-compatible photoconductive terahertz emitters based on plasmonic nano-antenna arrays.

    PubMed

    Yardimci, Nezih Tolga; Lu, Hong; Jarrahi, Mona

    2016-11-07

    We present a high-power and broadband photoconductive terahertz emitter operating at telecommunication optical wavelengths, at which compact and high-performance fiber lasers are commercially available. The presented terahertz emitter utilizes an ErAs:InGaAs substrate to achieve high resistivity and short carrier lifetime characteristics required for robust operation at telecommunication optical wavelengths. It also uses a two-dimensional array of plasmonic nano-antennas to offer significantly higher optical-to-terahertz conversion efficiencies compared to the conventional photoconductive emitters, while maintaining broad operation bandwidths. We experimentally demonstrate pulsed terahertz radiation over 0.1-5 THz frequency range with the power levels as high as 300 μW. This is the highest-reported terahertz radiation power from a photoconductive emitter operating at telecommunication optical wavelengths.

  4. Astigmatism in reflector antennas.

    NASA Technical Reports Server (NTRS)

    Cogdell, J. R.; Davis, J. H.

    1973-01-01

    Astigmatic phase error in large parabolic reflector antennas is discussed. A procedure for focusing an antenna and diagnosing the presence and degree of astigmatism is described. Theoretical analysis is conducted to determine the nature of this error in such antennas.

  5. On fast iterative mapping algorithms for stripe based coarse-grained reconfigurable architectures

    NASA Astrophysics Data System (ADS)

    Mehta, Gayatri; Patel, Krunalkumar; Pollard, Nancy S.

    2015-01-01

    Reconfigurable devices have potential for great flexibility/efficiency, but mapping algorithms onto these architectures is a long-standing challenge. This paper addresses this challenge for stripe based coarse-grained reconfigurable architectures (CGRAs) by drawing on insights from graph drawing. We adapt fast, iterative algorithms from hierarchical graph drawing to the problem of mapping to stripe based architectures. We find that global sifting is 98 times as fast as simulated annealing and produces very compact designs with 17% less area on average, at a cost of 5% greater wire length. Interleaving iterations of Sugiyama and global sifting is 40 times as fast as simulated annealing and achieves somewhat more compact designs with 1.8% less area on average, at a cost of only 1% greater wire length. These solutions can enable fast design space exploration, rapid performance testing, and flexible programming of CGRAs "in the field."

  6. SASAgent: an agent based architecture for search, retrieval and composition of scientific models.

    PubMed

    Felipe Mendes, Luiz; Silva, Laryssa; Matos, Ely; Braga, Regina; Campos, Fernanda

    2011-07-01

    Scientific computing is a multidisciplinary field that goes beyond the use of computer as machine where researchers write simple texts, presentations or store analysis and results of their experiments. Because of the huge hardware/software resources invested in experiments and simulations, this new approach to scientific computing currently adopted by research groups is well represented by e-Science. This work aims to propose a new architecture based on intelligent agents to search, recover and compose simulation models, generated in the context of research projects related to biological domain. The SASAgent architecture is described as a multi-tier, comprising three main modules, where CelO ontology satisfies requirements put by e-science projects mainly represented by the semantic knowledge base. Preliminary results suggest that the proposed architecture is promising to achieve requirements found in e-Science projects, considering mainly the biological domain. Copyright © 2011 Elsevier Ltd. All rights reserved.

  7. An Overview of NASA Glenn Research Center's Antenna R&D and Technology Efforts

    NASA Technical Reports Server (NTRS)

    Miranda, Felix A.

    2002-01-01

    This viewgraph presentation provides an overview of antenna research and design efforts being performed at NASA's Glenn Research Center. The following type of antenna research projects are discussed: phased array antennas, thin film ferroelectric reflectarray antenna, microelectromechanical systems (MEMs) based antennas and multi-beam antennas. Project overviews, design issues and research problems for each type of antenna system are covered. Additional topics reviewed included: communication systems of the future and a facility description.

  8. The directing effect of linking units on building microporous architecture in tetraphenyladmantane-based poly(Schiff base) networks.

    PubMed

    Li, Guiyang; Zhang, Biao; Yan, Jun; Wang, Zhonggang

    2014-02-21

    Tetraphenyladamantane-based porous poly(Schiff base)s with BET surface area (>1000 m(2) g(-1)), CO2 uptake (15 wt%, 273 K/1 bar) and H2 uptake (1.26 wt%, 77 K/1 bar) were synthesized. The structure-directing effect of isomers of phenyl diamines on building porous architecture was investigated.

  9. A phased array tracking antenna for vehicles

    NASA Technical Reports Server (NTRS)

    Ohmori, Shingo; Mano, Kazukiko; Tanaka, Kenji; Matsunaga, Makoto; Tsuchiya, Makio

    1990-01-01

    An antenna system including antenna elements and a satellite tracking method is considered a key technology in implementing land mobile satellite communications. In the early stage of land mobile satellite communications, a mechanical tracking antenna system is considered the best candidate for vehicles, however, a phased array antenna will replace it in the near future, because it has many attractive advantages such as a low and compact profile, high speed tracking, and potential low cost. Communications Research Laboratory is now developing a new phased array antenna system for land vehicles based on research experiences of the airborne phased array antenna, which was developed and evaluated in satellite communication experiments using the ETS-V satellite. The basic characteristics of the phased array antenna for land vehicles are described.

  10. Hybrid RF and Digital Beamformer for Cellular Networks: Algorithms, Microwave Architectures, and Measurements

    NASA Astrophysics Data System (ADS)

    Venkateswaran, Vijay; Pivit, Florian; Guan, Lei

    2016-07-01

    Modern wireless communication networks, particularly cellular networks utilize multiple antennas to improve the capacity and signal coverage. In these systems, typically an active transceiver is connected to each antenna. However, this one-to-one mapping between transceivers and antennas will dramatically increase the cost and complexity of a large phased antenna array system. In this paper, firstly we propose a \\emph{partially adaptive} beamformer architecture where a reduced number of transceivers with a digital beamformer (DBF) is connected to an increased number of antennas through an RF beamforming network (RFBN). Then, based on the proposed architecture, we present a methodology to derive the minimum number of transceivers that are required for marco-cell and small-cell base stations, respectively. Subsequently, in order to achieve optimal beampatterns with given cellular standard requirements and RF operational constraints, we propose efficient algorithms to jointly design DBF and RFBN. Starting from the proposed algorithms, we specify generic microwave RFBNs for optimal marco-cell and small-cell networks. In order to verify the proposed approaches, we compare the performance of RFBN using simulations and anechoic chamber measurements. Experimental measurement results confirm the robustness and performance of the proposed hybrid DBF-RFBN concept eventually ensuring that theoretical multi-antenna capacity and coverage are achieved at a little incremental cost.

  11. Breadboard Signal Processor for Arraying DSN Antennas

    NASA Technical Reports Server (NTRS)

    Jongeling, Andre; Sigman, Elliott; Chandra, Kumar; Trinh, Joseph; Soriano, Melissa; Navarro, Robert; Rogstad, Stephen; Goodhart, Charles; Proctor, Robert; Jourdan, Michael; Rayhrer, Benno

    2008-01-01

    A recently developed breadboard version of an advanced signal processor for arraying many antennas in NASA s Deep Space Network (DSN) can accept inputs in a 500-MHz-wide frequency band from six antennas. The next breadboard version is expected to accept inputs from 16 antennas, and a following developed version is expected to be designed according to an architecture that will be scalable to accept inputs from as many as 400 antennas. These and similar signal processors could also be used for combining multiple wide-band signals in non-DSN applications, including very-long-baseline interferometry and telecommunications. This signal processor performs functions of a wide-band FX correlator and a beam-forming signal combiner. [The term "FX" signifies that the digital samples of two given signals are fast Fourier transformed (F), then the fast Fourier transforms of the two signals are multiplied (X) prior to accumulation.] In this processor, the signals from the various antennas are broken up into channels in the frequency domain (see figure). In each frequency channel, the data from each antenna are correlated against the data from each other antenna; this is done for all antenna baselines (that is, for all antenna pairs). The results of the correlations are used to obtain calibration data to align the antenna signals in both phase and delay. Data from the various antenna frequency channels are also combined and calibration corrections are applied. The frequency-domain data thus combined are then synthesized back to the time domain for passing on to a telemetry receiver

  12. Flexible microstrip antennas

    NASA Astrophysics Data System (ADS)

    Cano Barrera, Camilo Antonio

    2013-05-01

    Actually the technological community has an interest in developing flexible circuits and antennas with particular characteristics e.g. robust, flexible, lightweight load-bearing, economical and efficient antennas for integrated millimeter wave systems. Microstrip antennas are an excellent solution because those have all the characteristics before mentioned, but they have the problem of being rigid antennas and this makes impossible that those antennas can be use in portable devices. A practical solution is developing flexible microstrip antennas that can be integrated to different devices. One axis of work is the analysis of the electromagnetic field to the microstrip antennas using Bessel function and after generalize for application inflexible microstrip antennas.

  13. Towards a State Based Control Architecture for Large Telescopes: Laying a Foundation at the VLT

    NASA Technical Reports Server (NTRS)

    Karban, R.; Kornweibel, N.; Dvorak, D.; Ingham, M.; Wagner, D.

    2011-01-01

    Large telescopes are characterized by a high level of distribution of control-related tasks and will feature diverse data flow patterns and large ranges of sampling frequencies; there will often be no single, fixed server-client relationship between the control tasks. the architecture is also challenged by the task of integrating heterogeneous subsystems which will be delivered by multiple different contractors. Due to the high number of distributed components, the control system needs to effectively detect errors and faults, impede their propagation, and accurately mitigate them in the shortest time possible, enabling the service to be restored. The presented Data-Driven Architecture is based on a decentralized approach with an end-to-end integration of disparate, independently developed software components. These components employ a high-performance standards-based communication middle-ware infrastructure, based on the Data Distribution Service. A set of rules and principles, based on JPL's State Analysis method and architecture, are use to constrain component-to component interactions, where the Control System and System Under Control are clearly separated. State Analysis provide a model-based process for capturing system and software requirements and design, greatly reducing the gap between the requirements on software specified by systems engineers and the implementation by software engineers. The method and architecture has been field tested at the Very Large Telescope, where it has been integrated into an operational system.

  14. Towards a State Based Control Architecture for Large Telescopes: Laying a Foundation at the VLT

    NASA Technical Reports Server (NTRS)

    Karban, R.; Kornweibel, N.; Dvorak, D.; Ingham, M.; Wagner, D.

    2011-01-01

    Large telescopes are characterized by a high level of distribution of control-related tasks and will feature diverse data flow patterns and large ranges of sampling frequencies; there will often be no single, fixed server-client relationship between the control tasks. the architecture is also challenged by the task of integrating heterogeneous subsystems which will be delivered by multiple different contractors. Due to the high number of distributed components, the control system needs to effectively detect errors and faults, impede their propagation, and accurately mitigate them in the shortest time possible, enabling the service to be restored. The presented Data-Driven Architecture is based on a decentralized approach with an end-to-end integration of disparate, independently developed software components. These components employ a high-performance standards-based communication middle-ware infrastructure, based on the Data Distribution Service. A set of rules and principles, based on JPL's State Analysis method and architecture, are use to constrain component-to component interactions, where the Control System and System Under Control are clearly separated. State Analysis provide a model-based process for capturing system and software requirements and design, greatly reducing the gap between the requirements on software specified by systems engineers and the implementation by software engineers. The method and architecture has been field tested at the Very Large Telescope, where it has been integrated into an operational system.

  15. Pax permanent Martian base: Space architecture for the first human habitation on Mars, volume 5

    NASA Technical Reports Server (NTRS)

    Huebner-Moths, Janis; Fieber, Joseph P.; Rebholz, Patrick J.; Paruleski, Kerry L.; Moore, Gary T. (Editor)

    1992-01-01

    America at the Threshold: Report of the Synthesis Group on America's Space Exploration Initiative (the 'Synthesis Report,' sometimes called the Stafford Report after its astronaut chair, published in 1991) recommended that NASA explore what it called four 'architectures,' i.e., four different scenarios for habitation on Mars. The Advanced Design Program in Space Architecture at the University of Wisconsin-Milwaukee supported this report and two of its scenarios--'Architecture 1' and 'Architecture 4'--during the spring of 1992. This report investigates the implications of different mission scenarios, the Martian environment, supporting technologies, and especially human factors and environment-behavior considerations for the design of the first permanent Martian base. The report is comprised of sections on mission analysis, implications of the Martian atmosphere and geologic environment, development of habitability design requirements based on environment-behavior and human factors research, and a full design proposed (concept design and design development) for the first permanent Martian base and habitat. The design is presented in terms of a base site plan, master plan based on a Mars direct scenario phased through IOC, and design development details of a complete Martian habitat for 18 crew members including all laboratory, mission control, and crew support spaces.

  16. Developments of FPGA-based digital back-ends for low frequency antenna arrays at Medicina radio telescopes

    NASA Astrophysics Data System (ADS)

    Naldi, G.; Bartolini, M.; Mattana, A.; Pupillo, G.; Hickish, J.; Foster, G.; Bianchi, G.; Lingua, A.; Monari, J.; Montebugnoli, S.; Perini, F.; Rusticelli, S.; Schiaffino, M.; Virone, G.; Zarb Adami, K.

    In radio astronomy Field Programmable Gate Array (FPGA) technology is largely used for the implementation of digital signal processing techniques applied to antenna arrays. This is mainly due to the good trade-off among computing resources, power consumption and cost offered by FPGA chip compared to other technologies like ASIC, GPU and CPU. In the last years several digital backend systems based on such devices have been developed at the Medicina radio astronomical station (INAF-IRA, Bologna, Italy). Instruments like FX correlator, direct imager, beamformer, multi-beam system have been successfully designed and realized on CASPER (Collaboration for Astronomy Signal Processing and Electronics Research, https://casper.berkeley.edu) processing boards. In this paper we present the gained experience in this kind of applications.

  17. Evolving the Web-Based Distributed SI/PDO Architecture for High-Performance Visualization

    SciTech Connect

    HOLMES,VICTOR P.; LINEBARGER,JOHN M.; MILLER,DAVID J.; VANDEWART,RUTHE LYNN; CROWLEY,CHARLES P.

    2000-08-16

    The Simulation Intranet/Product Database Operator (SI/PDO) project has developed a Web-based distributed object architecture for high performance scientific simulation. A Web-based Java interface guides designers through the design and analysis cycle via solid and analytical modeling, meshing, finite element simulation, and various forms of visualization. The SI/PDO architecture has evolved in steps towards satisfying Sandia's long-term goal of providing an end-to-end set of services for high fidelity full physics simulations in a high-performance, distributed, and distance computing environment. This paper describes the continuing evolution of the architecture to provide high-performance visualization services. Extensions to the SI/PDO architecture allow web access to visualization tools that run on MP systems. This architecture makes these tools more easily accessible by providing web-based interfaces and by shielding the user from the details of these computing environments. The design is a multi-tier architecture, where the Java-based GUI tier runs on a web browser and provides image display and control functions. The computation tier runs on MP machines. The middle tiers provide custom communication with MP machines, remote file selection, remote launching of services, load balancing, and machine selection. The architecture allows middleware of various types (CORBA, COM, RMI, sockets, etc.) to connect the tiers depending upon the situation. Testing of constantly developing visualization tools can be done in an environment where there are only two tiers which both run on desktop machines. This allows fast testing turnaround and does not use compute cycles on high-performance machines. Once the code and interfaces are tested, they are moved to high-performance machines, and new tiers are added to handle the problems of using these machines. Uniform interfaces are used throughout the tiers to allow this flexibility. Experiments test the appropriate level of

  18. Optical slot antenna and its application

    NASA Astrophysics Data System (ADS)

    Park, Yeonsang; Kim, Jineun; Roh, Young-Geun; Park, Q.-Han

    2017-02-01

    We present an optical slot antenna and its application. By measuring transmission spectra and far-field radiation pattern of metallic slots with nanometer scale, we show that a metallic nanoslot has the properties of an antenna, which are resonance, polarization, and bidirectional far-field radiation pattern, and can be regarded as a magnetic dipole in optical region. Additionally, we also make the unidirectional radiation by adapting the geometry of RF Yagi-Uda antenna and applying slot antenna. By the aid of phase analysis based on 3-dimensional finite-difference time-domain simulation, we can increase the front-to-back ratio of an optical slot Yagi-Uda antenna up to about 5. As the application of a slot antenna, we integrate a metal-insulator-metal plasmonic waveguide with a slot antenna. A surface plasmon waveguide mode propagating in MIM structure is well-coupled to a slot antenna and radiates into free-space in form of dipole radiation. By adding an auxiliary structure that has the role of reflector as like a slot Yagi-Uda antenna, the direction of radiation from a slot antenna integrated with a plasmonic waveguide can be controlled efficiently. Besides the possibility of integration with a waveguide, we expect that a slot antenna can be applied to active devices such as light emitting diodes or lasers for the future.

  19. Wavelet-Based Adaptive Solvers on Multi-core Architectures for the Simulation of Complex Systems

    NASA Astrophysics Data System (ADS)

    Rossinelli, Diego; Bergdorf, Michael; Hejazialhosseini, Babak; Koumoutsakos, Petros

    We build wavelet-based adaptive numerical methods for the simulation of advection dominated flows that develop multiple spatial scales, with an emphasis on fluid mechanics problems. Wavelet based adaptivity is inherently sequential and in this work we demonstrate that these numerical methods can be implemented in software that is capable of harnessing the capabilities of multi-core architectures while maintaining their computational efficiency. Recent designs in frameworks for multi-core software development allow us to rethink parallelism as task-based, where parallel tasks are specified and automatically mapped into physical threads. This way of exposing parallelism enables the parallelization of algorithms that were considered inherently sequential, such as wavelet-based adaptive simulations. In this paper we present a framework that combines wavelet-based adaptivity with the task-based parallelism. We demonstrate good scaling performance obtained by simulating diverse physical systems on different multi-core and SMP architectures using up to 16 cores.

  20. State-based scheduling: An architecture for telescope observation scheduling

    NASA Technical Reports Server (NTRS)

    Muscettola, Nicola; Smith, Stephen F.

    1989-01-01

    The applicability of constraint-based scheduling, a methodology previously developed and validated in the domain of factory scheduling, is extended to problem domains that require attendance to a wider range of state-dependent constraints. The problem of constructing and maintaining a short-term observation schedule for the Hubble Space Telescope (HST), which typifies this type of domain is the focus of interest. The nature of the constraints encountered in the HST domain is examined, system requirements are discussed with respect to utilization of a constraint-based scheduling methodology in such domains, and a general framework for state-based scheduling is presented.