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Sample records for downlink sinr distribution

  1. Communication system technology for demonstration of BB84 quantum key distribution in optical aircraft downlinks

    NASA Astrophysics Data System (ADS)

    Moll, Florian; Nauerth, Sebastian; Fuchs, Christian; Horwath, Joachim; Rau, Markus; Weinfurter, Harald

    2012-10-01

    Quantum Key Distribution (QKD), either fiber based or free-space, allows for provably secure key distribution solely based on the laws of quantum mechanics. Feasibility of QKD systems in aircraft-ground links was demonstrated with a successful key exchange. Experiment flights were undertaken during night time at the site of the German Aerospace Center (DLR) Oberpfaffenhofen, Germany. The aircraft was a Dornier 228 equipped with a laser communication terminal, originally designed for optical data downlinks with intensity modulation and direct detection. The counter terminal on ground was an optical ground station with a 40 cm Cassegrain type receiver telescope. Alice and Bob, as the transmitter and receiver systems usually are called in QKD, were integrated in the flight and ground terminals, respectively. A second laser source with 1550 nm wavelength was used to transmit a 100 MHz signal for synchronization of the two partners. The so called BB84 protocol, here implemented with faint polarization encoded pulses at 850nm wavelength, was applied as key generation scheme. Within two flights, measurements of the QKD and communication channel could be obtained with link distance of 20 km. After link acquisition, the tracking systems in the aircraft and on ground were able to keep lock of the narrow QKD beam. Emphasis of this paper is put on presentation of the link technology, i.e. link design and modifications of the communication terminals. First analysis of link attenuation, performance of the QKD system and scintillation of the sync signal is also addressed.

  2. SINR estimation for SATCOM in the environment with jamming signals

    NASA Astrophysics Data System (ADS)

    Li, Lun; Wang, Gang; Tian, Xin; Shen, Dan; Pham, Khanh; Blasch, Erik; Chen, Genshe

    2016-05-01

    In this paper we consider a problem of estimating the signal-to-interference-plus-noise ratio (SINR) for satellite transmission system in the presence of jamming signals. Additive white Gaussian noise (AWGN) channels are considered for baseband quadrature phase shift keying (QPSK) data transmission system. Two interference models are proposed with Gaussian or non-Gaussian interference signals in order to investigate the SINR for different satellite transmission jamming scenarios. Both non-data-aided moment-based and data-aided maxi-mum likelihood SINR estimators are derived for the systems. The normalized mean square errors of the SINR estimation algorithms are examined by means of computer simulations. The numerical results show the robust-ness of derived SINR estimators. The development of the SINR estimators are applicable to a large number of applications utilizing satellite communication systems.

  3. SINR estimation for SATCOM in the environment with jamming signals

    NASA Astrophysics Data System (ADS)

    Li, Lun; Wang, Gang; Tian, Xin; Shen, Dan; Pham, Khanh; Blasch, Erik; Chen, Genshe

    2016-05-01

    In this paper we consider a problem of estimating the signal-to-interference-plus-noise ratio (SINR) for satellite transmission system in the presence of jamming signals. Additive white Gaussian noise (AWGN) channels are considered for baseband quadrature phase shift keying (QPSK) data transmission system. Two interference models are proposed with Gaussian or non-Gaussian interference signals in order to investigate the SINR for different satellite transmission jamming scenarios. Both non-data-aided moment-based and data-aided maxi-mum likelihood SINR estimators are derived for the systems. The normalized mean square errors of the SINR estimation algorithms are examined by means of computer simulations. The numerical results show the robust-ness of derived SINR estimators. The development of the SINR estimators are applicable to a large number of applications utilizing satellite communication systems.

  4. Robust Linear MIMO in the Downlink: A Worst-Case Optimization with Ellipsoidal Uncertainty Regions

    NASA Astrophysics Data System (ADS)

    Zheng, Gan; Wong, Kai-Kit; Ng, Tung-Sang

    2008-12-01

    This paper addresses the joint robust power control and beamforming design of a linear multiuser multiple-input multiple-output (MIMO) antenna system in the downlink where users are subjected to individual signal-to-interference-plus-noise ratio (SINR) requirements, and the channel state information at the transmitter (CSIT) with its uncertainty characterized by an ellipsoidal region. The objective is to minimize the overall transmit power while guaranteeing the users' SINR constraints for every channel instantiation by designing the joint transmitreceive beamforming vectors robust to the channel uncertainty. This paper first investigates a multiuser MISO system (i.e., MIMO with single-antenna receivers) and by imposing the constraints on an SINR lower bound, a robust solution is obtained in a way similar to that with perfect CSI. We then present a reformulation of the robust optimization problem using S-Procedure which enables us to obtain the globally optimal robust power control with fixed transmit beamforming. Further, we propose to find the optimal robust MISO beamforming via convex optimization and rank relaxation. A convergent iterative algorithm is presented to extend the robust solution for multiuser MIMO systems with both perfect and imperfect channel state information at the receiver (CSIR) to guarantee the worst-case SINR. Simulation results illustrate that the proposed joint robust power and beamforming optimization significantly outperforms the optimal robust power allocation with zeroforcing (ZF) beamformers, and more importantly enlarges the feasibility regions of a multiuser MIMO system.

  5. An Eavesdropping Game with SINR as an Objective Function

    NASA Astrophysics Data System (ADS)

    Garnaev, Andrey; Trappe, Wade

    We examine eavesdropping over wireless channels, where secret communication in the presence of an eavesdropper is formulated as a zero-sum game. In our problem, the legitimate receiver does not have complete knowledge about the environment, i.e. does not know the exact values of the channels gains, but instead knows just their distribution. To communicate secretly, the user must decide how to transmit its information across subchannels under a worst-case condition and thus, the legal user faces a max-min optimization problem. To formulate the optimization problem, we pose the environment as a secondary player in a zero-sum game whose objective is to hamper communication by the user. Thus, nature faces a min-max optimization problem. In our formulation, we consider signal-to-interference ratio (SINR) as a payoff function. We then study two specific scenarios: (i) the user does not know the channels gains; and (ii) the user does not know how the noise is distributed among the main channels. We show that in model (i) in his optimal behavior the user transmits signal energy uniformly across a subset of selected channels. In model (ii), if the user does not know the eavesdropper’s channel gains he/she also employs a strategy involving uniformly distributing energy across a subset of channels. However, if the user acquires extra knowledge about environment, e.g. the eavesdropper’s channel gains, the user may better tune his/her power allocation among the channels. We provide criteria for selecting which channels the user should transmit on by deriving closed-form expressions for optimal strategies for both players.

  6. Structure and organisation of SinR, the master regulator of biofilm formation in Bacillus subtilis.

    PubMed

    Colledge, Vicki L; Fogg, Mark J; Levdikov, Vladimir M; Leech, Andrew; Dodson, Eleanor J; Wilkinson, Anthony J

    2011-08-19

    sinR encodes a tetrameric repressor of genes required for biofilm formation in Bacillus subtilis. sinI, which is transcribed under Spo0A control, encodes a dimeric protein that binds to SinR to form a SinR-SinI heterodimer in which the DNA-binding functions of SinR are abrogated and repression of biofilm genes is relieved. The heterodimer-forming surface comprises residues conserved between SinR and SinI. Each forms a pair of α-helices that hook together to form an intermolecular four-helix bundle. Here, we are interested in the assembly of the SinR tetramer and its binding to DNA. Size-exclusion chromatography with multi-angle laser light scattering and crystallographic analysis reveal that a DNA-binding fragment of SinR (residues 1-69) is a monomer, while a SinI-binding fragment (residues 74-111) is a tetramer arranged as a dimer of dimers. The SinR(74-111) chain forms two α-helices with the organisation of the dimer similar to that observed in the SinR-SinI complex. The tetramer is formed through interactions of residues at the C-termini of the four chains. A model of the intact SinR tetramer in which the DNA binding domains surround the tetramerisation core was built. Fluorescence anisotropy and surface plasmon resonance experiments showed that SinR binds to an oligonucleotide duplex, 5'-TTTGTTCTCTAAAGAGAACTTA-3', containing a pair of SinR consensus sequences in inverted orientation with a K(d) of 300 nM. The implications of these data for promoter binding and the curious quaternary structural transitions of SinR upon binding to (i) SinI and (ii) the SinR-like protein SlrR, which "repurposes" SinR as a repressor of autolysin and motility genes, are discussed.

  7. Selecting Pixels for Kepler Downlink

    NASA Technical Reports Server (NTRS)

    Bryson, Stephen T.; Jenkins, Jon M.; Klaus, Todd C.; Cote, Miles T.; Quintana, Elisa V.; Hall, Jennifer R.; Ibrahim, Khadeejah; Chandrasekaran, Hema; Caldwell, Douglas A.; Van Cleve, Jeffrey E.; Haas, Michael R.

    2010-01-01

    The Kepler mission monitors > 100,000 stellar targets using 42 2200 1024 pixel CCDs. Bandwidth constraints prevent the downlink of all 96 million pixels per 30-minute cadence, so the Kepler spacecraft downlinks a specified collection of pixels for each target. These pixels are selected by considering the object brightness, background and the signal-to-noise of each pixel, and are optimized to maximize the signal-to-noise ratio of the target. This paper describes pixel selection, creation of spacecraft apertures that efficiently capture selected pixels, and aperture assignment to a target. Diagnostic apertures, short-cadence targets and custom specified shapes are discussed.

  8. Structure and Organisation of SinR, the Master Regulator of Biofilm Formation in Bacillus subtilis

    PubMed Central

    Colledge, Vicki L.; Fogg, Mark J.; Levdikov, Vladimir M.; Leech, Andrew; Dodson, Eleanor J.; Wilkinson, Anthony J.

    2011-01-01

    sinR encodes a tetrameric repressor of genes required for biofilm formation in Bacillus subtilis. sinI, which is transcribed under Spo0A control, encodes a dimeric protein that binds to SinR to form a SinR–SinI heterodimer in which the DNA-binding functions of SinR are abrogated and repression of biofilm genes is relieved. The heterodimer-forming surface comprises residues conserved between SinR and SinI. Each forms a pair of α-helices that hook together to form an intermolecular four-helix bundle. Here, we are interested in the assembly of the SinR tetramer and its binding to DNA. Size-exclusion chromatography with multi-angle laser light scattering and crystallographic analysis reveal that a DNA-binding fragment of SinR (residues 1–69) is a monomer, while a SinI-binding fragment (residues 74–111) is a tetramer arranged as a dimer of dimers. The SinR(74–111) chain forms two α-helices with the organisation of the dimer similar to that observed in the SinR–SinI complex. The tetramer is formed through interactions of residues at the C-termini of the four chains. A model of the intact SinR tetramer in which the DNA binding domains surround the tetramerisation core was built. Fluorescence anisotropy and surface plasmon resonance experiments showed that SinR binds to an oligonucleotide duplex, 5′-TTTGTTCTCTAAAGAGAACTTA-3′, containing a pair of SinR consensus sequences in inverted orientation with a Kd of 300 nM. The implications of these data for promoter binding and the curious quaternary structural transitions of SinR upon binding to (i) SinI and (ii) the SinR-like protein SlrR, which “repurposes” SinR as a repressor of autolysin and motility genes, are discussed. PMID:21708175

  9. Spacecraft Reed-Solomon downlink module

    NASA Technical Reports Server (NTRS)

    Luong, Huy H. (Inventor); Donaldson, James A. (Inventor); Wood, Steven H. (Inventor)

    1998-01-01

    Apparatus and method for providing downlink frames to be transmitted from a spacecraft to a ground station. Each downlink frame includes a synchronization pattern and a transfer frame. The apparatus may comprise a monolithic Reed-Solomon downlink (RSDL) encoding chip coupled to data buffers for storing transfer frames. The RSKL chip includes a timing device, a bus interface, a timing and control unit, a synchronization pattern unit, and a Reed-Solomon encoding unit, and a bus arbiter.

  10. Multivariate Fronthaul Quantization for Downlink C-RAN

    NASA Astrophysics Data System (ADS)

    Lee, Wonju; Simeone, Osvaldo; Kang, Joonhyuk; Shamai, Shlomo

    2016-10-01

    The Cloud-Radio Access Network (C-RAN) cellular architecture relies on the transfer of complex baseband signals to and from a central unit (CU) over digital fronthaul links to enable the virtualization of the baseband processing functionalities of distributed radio units (RUs). The standard design of digital fronthauling is based on either scalar quantization or on more sophisticated point to-point compression techniques operating on baseband signals. Motivated by network-information theoretic results, techniques for fronthaul quantization and compression that improve over point-to-point solutions by allowing for joint processing across multiple fronthaul links at the CU have been recently proposed for both the uplink and the downlink. For the downlink, a form of joint compression, known in network information theory as multivariate compression, was shown to be advantageous under a non-constructive asymptotic information-theoretic framework. In this paper, instead, the design of a practical symbol-by-symbol fronthaul quantization algorithm that implements the idea of multivariate compression is investigated for the C-RAN downlink. As compared to current standards, the proposed multivariate quantization (MQ) only requires changes in the CU processing while no modification is needed at the RUs. The algorithm is extended to enable the joint optimization of downlink precoding and quantization, reduced-complexity MQ via successive block quantization, and variable-length compression. Numerical results, which include performance evaluations over standard cellular models, demonstrate the advantages of MQ and the merits of a joint optimization with precoding.

  11. Sum-SINR/sum-capacity optimal multisignature spread-spectrum steganography

    NASA Astrophysics Data System (ADS)

    Wei, Lili; Pados, Dimitris A.; Batalama, Stella N.; Medley, Michael J.

    2008-04-01

    For any given digital host image or audio file (or group of hosts) and any (block) transform domain of interest, we find an orthogonal set of signatures that achieves maximum sum-signal-to-interference-plus-noise ratio (sum- SINR) spread-spectrum message embedding for any fixed embedding amplitude values. We also find the sumcapacity optimal amplitude allocation scheme for any given total distortion budget under the assumption of (colored) Gaussian transform-domain host data. The practical implication of the results is sum-SINR, sumcapacity optimal multiuser/multisignature spread-spectrum data hiding in the same medium. Theoretically, the findings establish optimality of the recently presented Gkizeli-Pados-Medley multisignature eigen-design algorithm.

  12. Characteristics of annular beams propagating through atmospheric turbulence along a downlink path and an uplink path

    NASA Astrophysics Data System (ADS)

    Ji, Xiaoling; Chen, Hong; Ji, Guangming

    2016-08-01

    Characteristics of annular beams propagating through atmospheric turbulence along a downlink path and an uplink path are studied in detail by using numerical simulation method. It is found that in downlink the influence of atmospheric turbulence on the characteristics is quite different from that in uplink because of the altitude-dependent index structure constant. It is shown that, when the zenith angle θ is not large enough, it is always σ_{{I {{up}}}}2 > σ_{{I {{down}}}}2 on propagation whatever the value of the obscure ratio ɛ is, where σ_{{I {{up}}}}2 and σ_{{I {{down}}}}2 are the on-axis scintillation index in uplink and downlink, respectively. However, when θ is large enough, σ_{{I {{down}}}}2 is close to σ_{{I {{up}}}}2 as the propagation distance z increases, and σ_{{I {{up}}}}2 and σ_{{I {{down}}}}2 overlap each other as ɛ increases. Furthermore, as z increases, σ_{{I {{up}}}}2 approaches an asymptotical value when θ is not large enough, and the saturation phenomenon of σ_{{I {{up}}}}2 appears when θ is large enough. But the asymptotical value and the saturation phenomenon of σ_{{I {{down}}}}2 never appear. On the other hand, the energy focusability in downlink is better than that in uplink, and the difference of energy focusability between a downlink and an uplink increases with increasing θ or decreasing ɛ. In addition, in downlink there may exist sidelobes of intensity distributions when θ is not large enough, but the sidelobes never appear in uplink.

  13. SINR Analysis of Hexagonal Multicarrier Transmission Systems in the Presence of Insufficient Synchronization for Doubly Dispersive Channel

    NASA Astrophysics Data System (ADS)

    Xu, Kui; Xu, Youyun; Zhang, Dongmei

    2011-07-01

    This paper analyzes the effect of the insufficient synchronization (carrier frequency offset, timing offset) on hexagonal multicarrier transmission (HMT) systems for doubly dispersive channel. Exact SINR and demodulated symbol expressions for HMT systems in the presence of insufficient synchronization transmission conditions over doubly dispersive channel with exponential delay power profile and U-shape Doppler power spectrum and uniform delay power profile and uniform Doppler power spectrum are derived, respectively. Theoretical analysis shows that similar degradations on symbol amplitude and phase caused by insufficient synchronization are incurred as in traditional cyclic-prefix orthogonal frequency division multiplexing (CP-OFDM) transmission. HMT systems outperform traditional OFDM systems with respect to signal to interference-plus-noise-ratio (SINR) against inter-symbol interference (ISI) and inter-carrier interference (ICI) caused by insufficient synchronization and doubly dispersive(DD) channel. The BER performance of the HMT systems using Monte Carlo simulation match with the conclusion given by the proposed exact SINR expression.

  14. Downlinks for DBS - Design and engineering considerations

    NASA Astrophysics Data System (ADS)

    Blecker, M.; Martin, E. R.

    1985-01-01

    The subsystem interrelationships and design parameters choice procedures for a DBS downlink design are discussed from a business decisions point of view. The image quality is determined by customer satisfaction, which is translated to a required carrier/noise (C/N) ratio. The C/N ratio defines acceptable levels of signal fading, a subjective value which is modified by the demographics of the service area. Increasing the satellite on-board transmitting power to meet acceptable broadcast reliability places burdens on the start-up capitalization of the business. Larger receiving antennas in rural areas ameliorates some of the power requirements. The dish size, however, affects the labor costs of installation, but must be kept small enough to be used in heavily populated areas. The satellites must be built, as far as is possible, from off-the-shelf components to keep costs down. Design selections for a sample complete system are listed.

  15. Improved MLWDF scheduler for LTE downlink transmission

    NASA Astrophysics Data System (ADS)

    Obinna Nnamani, Christantus; Anioke, Chidera Linda; Ikechukwu Ani, Cosmas

    2016-11-01

    In long-term evolution (LTE) downlink transmission, modified least weighted delay first (MLWDF) scheduler is a quality of service (QoS) aware scheduling scheme for real-time (RT) services. Nevertheless, MLWDF performs below optimal among the trade-off between strict delay and loss restraints of RT and non-RT traffic flows, respectively. This is further worsened with the implementation of hybrid automatic retransmission request (HARQ). As these restraints grow unabated with increasing number of user demands, the performance of MLWDF further reduces. In order to ameliorate this situation, there is a need to directly incorporate the variations in user demands and HARQ implementation as parameters to the MLWDF scheduler. In this work, an improvement to the MLWDF scheduler is proposed. The improvement entails adding two novel parameters that characterise user demand and HARQ implementation. The scheduler was tested using varying three classes of service in QoS class identifiers (QCIs) table standardised by Third Generation Partnership Project for LTE network to characterise different services. It was also tested on the basis of packet prioritisation. The proposed scheduler was simulated with LTE-SIM simulator and compared with the MLWDF and proportional fairness schedulers. In terms of delay, throughput and packet loss ratio; the proposed scheduler increased overall system performance.

  16. A connectorized fiber downlink for FMOS

    NASA Astrophysics Data System (ADS)

    Murray, Graham J.; Luke, Peter; Robertson, David J.; Tamura, Naoyuki

    2003-04-01

    A consortium of UK, Australian and Japanese groups is designing a fibre-fed near IR (J & H band) multi-object spectrograph (FMOS) for the Subaru telescope. The prime focus of the telescope will support a 400-fibre multi-object positioning system, ECHIDNA. However, the IR spectrographs (of which there are two) are to be located close to the Nasmyth platform, so an interconnecting optical feed is required to deliver light from ECHIDNA. The Astronomical Instrumentation Group at the University of Durham is undertaking the design and construction of a suitable fibre-optic downlink. To allow the prime focus unit that houses ECHIDNA to be removed, the fibre cable is to include a connectorized break, located at the telescope top-end ring. The optical design also calls for a change in focal ratio from that delivered by ECHIDNA in order to couple light to the spectrograph with the greatest efficiency. This will be achieved in the connector coupling by means of an array of high-efficiency GRIN microlenses. The connector will additionally incorporate an integral back-illumination system for on-telescope testing and calibration. This paper describes the preliminary design of the fibre system that is to be constructed in Durham.

  17. Novel method of channel estimation for WCDMA downlink

    NASA Astrophysics Data System (ADS)

    Sheng, Bin; You, XiaoHu

    2001-10-01

    A novel scheme for channel estimation is proposed in this paper for WCDMA Downlink where a pilot channel is simultaneously transmitted with a dada traffic channel. The proposed scheme exploits channel information in both pilot and data traffic channels by combining channel estimates from these two channels. It is demonstrated by computer simulations that the performance of the Rake receiver is improved obviously.

  18. Downlink Probability Density Functions for EOS-McMurdo Sound

    NASA Technical Reports Server (NTRS)

    Christopher, P.; Jackson, A. H.

    1996-01-01

    The visibility times and communication link dynamics for the Earth Observations Satellite (EOS)-McMurdo Sound direct downlinks have been studied. The 16 day EOS periodicity may be shown with the Goddard Trajectory Determination System (GTDS) and the entire 16 day period should be simulated for representative link statistics. We desire many attributes of the downlink, however, and a faster orbital determination method is desirable. We use the method of osculating elements for speed and accuracy in simulating the EOS orbit. The accuracy of the method of osculating elements is demonstrated by closely reproducing the observed 16 day Landsat periodicity. An autocorrelation function method is used to show the correlation spike at 16 days. The entire 16 day record of passes over McMurdo Sound is then used to generate statistics for innage time, outage time, elevation angle, antenna angle rates, and propagation loss. The levation angle probability density function is compared with 1967 analytic approximation which has been used for medium to high altitude satellites. One practical result of this comparison is seen to be the rare occurrence of zenith passes. The new result is functionally different than the earlier result, with a heavy emphasis on low elevation angles. EOS is one of a large class of sun synchronous satellites which may be downlinked to McMurdo Sound. We examine delay statistics for an entire group of sun synchronous satellites ranging from 400 km to 1000 km altitude. Outage probability density function results are presented three dimensionally.

  19. Performance analysis of satellite-to-ground downlink coherent optical communications with spatial diversity over Gamma-Gamma atmospheric turbulence.

    PubMed

    Ma, Jing; Li, Kangning; Tan, Liying; Yu, Siyuan; Cao, Yubin

    2015-09-01

    The performances of satellite-to-ground downlink optical communications over Gamma-Gamma distributed atmospheric turbulence are studied for a coherent detection receiving system with spatial diversity. Maximum ratio combining (MRC) and selection combining (SC) techniques are considered as practical schemes to mitigate the atmospheric turbulence. Bit-error rate (BER) performances for binary phase-shift keying modulated coherent detection and outage probabilities are analyzed and compared for SC diversity using analytical results and for MRC diversity through an approximation method with different numbers of receiving aperture each with the same aperture area. To show the net diversity gain of a multiple aperture receiver system, BER performances and outage probabilities of MRC and SC multiple aperture receiver systems are compared with a single monolithic aperture with the same total aperture area (same total average incident optical power) for satellite-to-ground downlink optical communications. All the numerical results are verified by Monte-Carlo simulations. PMID:26368880

  20. Performance analysis of satellite-to-ground downlink optical communications with spatial diversity over Gamma-Gamma atmospheric turbulence

    NASA Astrophysics Data System (ADS)

    Li, Kangning; Ma, Jing; Belmonte, Aniceto; Tan, Liying; Yu, Siyuan

    2015-12-01

    The performances of satellite-to-ground downlink optical communications over Gamma-Gamma distributed turbulence are studied for a multiple-aperture receiver system. Equal gain-combining (EGC) and selection-combining (SC) techniques are considered as practical schemes to mitigate the atmospheric turbulence under thermal-noise-limited conditions. Bit-error rate (BER) performances for on-off keying-modulated direct detection and outage probabilities are analyzed and compared for SC diversity receptions using analytical results and for EGC diversity receptions through an approximation method. To show the net diversity gain of a multiple-aperture receiver system, BER performances and outage probabilities of EGC and SC receiver systems are compared with a single monolithic-aperture receiver system with the same total aperture area (same average total incident optical power) for satellite-to-ground downlink optical communications. All the numerical results are also verified by Monte-Carlo simulations.

  1. Performance analysis of satellite-to-ground downlink coherent optical communications with spatial diversity over Gamma-Gamma atmospheric turbulence.

    PubMed

    Ma, Jing; Li, Kangning; Tan, Liying; Yu, Siyuan; Cao, Yubin

    2015-09-01

    The performances of satellite-to-ground downlink optical communications over Gamma-Gamma distributed atmospheric turbulence are studied for a coherent detection receiving system with spatial diversity. Maximum ratio combining (MRC) and selection combining (SC) techniques are considered as practical schemes to mitigate the atmospheric turbulence. Bit-error rate (BER) performances for binary phase-shift keying modulated coherent detection and outage probabilities are analyzed and compared for SC diversity using analytical results and for MRC diversity through an approximation method with different numbers of receiving aperture each with the same aperture area. To show the net diversity gain of a multiple aperture receiver system, BER performances and outage probabilities of MRC and SC multiple aperture receiver systems are compared with a single monolithic aperture with the same total aperture area (same total average incident optical power) for satellite-to-ground downlink optical communications. All the numerical results are verified by Monte-Carlo simulations.

  2. Biofilm formation by Bacillus subtilis requires an endoribonuclease-containing multisubunit complex that controls mRNA levels for the matrix gene repressor SinR.

    PubMed

    DeLoughery, Aaron; Dengler, Vanina; Chai, Yunrong; Losick, Richard

    2016-01-01

    Biofilm formation by Bacillus subtilis is largely governed by a circuit in which the response regulator Spo0A turns on the gene for the anti-repressor SinI. SinI, in turn, binds to and inactivates SinR, a dedicated repressor of genes for matrix production. Mutants of the genes ylbF, ymcA and yaaT are blocked in biofilm formation, but the mechanism by which they act has been mysterious. A recent report attributed their role in biofilm formation to stimulating Spo0A activity. However, we detect no measurable effect on the transcription of sinI. Instead, we find that the block in biofilm formation is caused by an increase in the levels of SinR and of its mRNA. Evidence is presented that YlbF, YmcA and YaaT interact with, and control the activity of, RNase Y, which is known to destabilize sinR mRNA. We also show that the processing of another target of RNase Y, cggR-gapA mRNA, similarly depends on YlbF and YmcA. Our work suggests that sinR mRNA stability is an additional posttranscriptional control mechanism governing the switch to multicellularity and raises the possibility that YlbF, YmcA and YaaT broadly regulate mRNA stability as part of an RNase Y-containing, multi-subunit complex.

  3. Enhanced Handoff Scheme for Downlink-Uplink Asymmetric Channels in Cellular Systems

    PubMed Central

    2013-01-01

    In the latest cellular networks, data services like SNS and UCC can create asymmetric packet generation rates over the downlink and uplink channels. This asymmetry can lead to a downlink-uplink asymmetric channel condition being experienced by cell edge users. This paper proposes a handoff scheme to cope effectively with downlink-uplink asymmetric channels. The proposed handoff scheme exploits the uplink channel quality as well as the downlink channel quality to determine the appropriate timing and direction of handoff. We first introduce downlink and uplink channel models that consider the intercell interference, to verify the downlink-uplink channel asymmetry. Based on these results, we propose an enhanced handoff scheme that exploits both the uplink and downlink channel qualities to reduce the handoff-call dropping probability and the service interruption time. The simulation results show that the proposed handoff scheme reduces the handoff-call dropping probability about 30% and increases the satisfaction of the service interruption time requirement about 7% under high-offered load, compared to conventional mobile-assisted handoff. Especially, the proposed handoff scheme is more efficient when the uplink QoS requirement is much stricter than the downlink QoS requirement or uplink channel quality is worse than downlink channel quality. PMID:24501576

  4. Simplifying operations with an uplink/downlink integration toolkit

    NASA Technical Reports Server (NTRS)

    Murphy, Susan C.; Miller, Kevin J.; Guerrero, Ana Maria; Joe, Chester; Louie, John J.; Aguilera, Christine

    1994-01-01

    The Operations Engineering Lab (OEL) at JPL has developed a simple, generic toolkit to integrate the uplink/downlink processes, (often called closing the loop), in JPL's Multimission Ground Data System. This toolkit provides capabilities for integrating telemetry verification points with predicted spacecraft commands and ground events in the Mission Sequence Of Events (SOE) document. In the JPL ground data system, the uplink processing functions and the downlink processing functions are separate subsystems that are not well integrated because of the nature of planetary missions with large one-way light times for spacecraft-to-ground communication. Our new closed-loop monitoring tool allows an analyst or mission controller to view and save uplink commands and ground events with their corresponding downlinked telemetry values regardless of the delay in downlink telemetry and without requiring real-time intervention by the user. An SOE document is a time-ordered list of all the planned ground and spacecraft events, including all commands, sequence loads, ground events, significant mission activities, spacecraft status, and resource allocations. The SOE document is generated by expansion and integration of spacecraft sequence files, ground station allocations, navigation files, and other ground event files. This SOE generation process has been automated within the OEL and includes a graphical, object-oriented SOE editor and real-time viewing tool running under X/Motif. The SOE toolkit was used as the framework for the integrated implementation. The SOE is used by flight engineers to coordinate their operations tasks, serving as a predict data set in ground operations and mission control. The closed-loop SOE toolkit allows simple, automated integration of predicted uplink events with correlated telemetry points in a single SOE document for on-screen viewing and archiving. It automatically interfaces with existing real-time or non real-time sources of information, to

  5. Spacelab uplink/downlink data flow and formats

    NASA Technical Reports Server (NTRS)

    Kandefer, F.

    1978-01-01

    The results of an analysis of the Spacelab (SL) data uplink/downlink structure and those data system elements associated with the support of this data flow are presented. Specific objectives of this report are to present the results of the following analyses: (1) operations of the SL high rate multiplexer, including format structure, data rates, format combinations, format switching, etc.; (2) operations of SL data recorders to include the definition of modes, data rates and forms; (3) operations of the high rate demultiplexer as described above; (4) potential experiment data formats defining formatting parameters to be considered in decommutation analysis; (5) SL computer input/output (I/O) decommutation channels, including the definition of structure, quantity and use of this I/O data; (6) detailed requirements of the data quality monitoring philosophy for this function.

  6. Dr. Ravindra Lal follows a live downlink of experiments operations on shuttle

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Dr. Ravindra Lal, principal investigator for a crystal growth experiment for Spacelab 3, follows a live downlink of the experiments operations in the shuttle science module. He is in the payload operations control center (POCC) in JSC's mission control center.

  7. Ice depolarization on low-angle 2 GHz satellite downlinks

    NASA Technical Reports Server (NTRS)

    Stutzman, W. L.; Bostian, C. W.; Tsolakis, A.; Pratt, T.

    1984-01-01

    The impact of ice depolarization on the statistical performance of satellite downlinks were investigated. Propagation data recorded during 1979 and 1980 to see what impact of ice depolarization on link performance were analyzed. The effects on the cross polarization discrimination (XPD) statistics amounted to at most a 2 to 4 dB reduction in the XPD values which rain would have produced for a given percentage of time. Ice depolarization had no effect on the statistics of XPD values below the 0.01% level. Most of the severe ice depolarization events were associated with drops in barometric pressure and the passage of intense cold fronts through our area. Ice contents as the product of three individually undetermined quantities were defined: ice particle density, ice cloud thickness, and the average volume of the ice crystals. It is indicated that populations of ice particle with ice contents on the order of 0.002 m4/m3 are probably responsible for the lower values of measured XPD.

  8. Hyperspectral data compression study: defining the roadmap for data downlink and redistribution

    NASA Astrophysics Data System (ADS)

    Huang, Hung-Lung; Huang, Bormin; Schmit, Timothy J.; Heymann, Roger

    2003-06-01

    Given the unprecedented volume of data (>72 Megabits per second) that will be generated by the future NOAA Geostationary Operational Environmental Satellite (GOES-R and beyond), the use of innovative data compression techniques will be essential if continuous downlink and re-broadcast from geo-orbit are to be economically feasible. A team of scientists and engineers from the Cooperative Institute for Meteorological Satellite Studies (CIMSS) of the University of Wisconsin-Madison, Offices of Research and Applications and Systems Development of NOAA/NESDIS, NASA/GSFC, and The Aerospace Corporation (a Federally Funded Research and Development Center) has been assembled to study the development of data compression for the next generation GOES sounder. This study is intended to define some feasible approaches for achieving both on-board (lossless) and ground-based (lossy or lossless) data compression. In general, on-board systems have substantially limited processing and storage capabilities, and modest compression ratios, compared with those of ground-based systems. Both highly efficient lossless and lossy algorithms therefore need to be developed to meet both on-board and ground processing objectives. In particular, innovative compression techniques for optimal quantization, transformation, coding, and decoding in interferogram or spectral domains will be essential for practical NOAA real-time operational data processing and distribution. In this presentation we will clearly define testing data sets (real and simulated), approaches, performance and feasibility of achieving hyperspectral data compression to provide a manageable data rate.

  9. Prediction and comparison of downlink electric-field and uplink localised SAR values for realistic indoor wireless planning.

    PubMed

    Plets, David; Joseph, Wout; Aerts, Sam; Vanhecke, Kris; Vermeeren, Günter; Martens, Luc

    2014-12-01

    In this paper, for the first time a heuristic network calculator for both whole-body exposure due to indoor base station antennas or access points (downlink exposure) and localised exposure due to the mobile device (uplink exposure) in indoor wireless networks is presented. As an application, three phone call scenarios are investigated (Universal Mobile Telecommunications System (UMTS) macrocell, UMTS femtocell and WiFi voice-over-IP) and compared with respect to the electric-field strength and localised specific absorption rate (SAR) distribution. Prediction models are created and successfully validated with an accuracy of 3 dB. The benefits of the UMTS power control mechanisms are demonstrated. However, dependent on the macrocell connection quality and on the user's average phone call connection time, also the macrocell solution might be preferential from an exposure point of view for the considered scenario. PMID:24553049

  10. Robust THP Transceiver Designs for Multiuser MIMO Downlink with Imperfect CSIT

    NASA Astrophysics Data System (ADS)

    Ubaidulla, P.; Chockalingam, A.

    2009-12-01

    We present robust joint nonlinear transceiver designs for multiuser multiple-input multiple-output (MIMO) downlink in the presence of imperfections in the channel state information at the transmitter (CSIT). The base station (BS) is equipped with multiple transmit antennas, and each user terminal is equipped with one or more receive antennas. The BS employs Tomlinson-Harashima precoding (THP) for interuser interference precancellation at the transmitter. We consider robust transceiver designs that jointly optimize the transmit THP filters and receive filter for two models of CSIT errors. The first model is a stochastic error (SE) model, where the CSIT error is Gaussian-distributed. This model is applicable when the CSIT error is dominated by channel estimation error. In this case, the proposed robust transceiver design seeks to minimize a stochastic function of the sum mean square error (SMSE) under a constraint on the total BS transmit power. We propose an iterative algorithm to solve this problem. The other model we consider is a norm-bounded error (NBE) model, where the CSIT error can be specified by an uncertainty set. This model is applicable when the CSIT error is dominated by quantization errors. In this case, we consider a worst-case design. For this model, we consider robust (i) minimum SMSE, (ii) MSE-constrained, and (iii) MSE-balancing transceiver designs. We propose iterative algorithms to solve these problems, wherein each iteration involves a pair of semidefinite programs (SDPs). Further, we consider an extension of the proposed algorithm to the case with per-antenna power constraints. We evaluate the robustness of the proposed algorithms to imperfections in CSIT through simulation, and show that the proposed robust designs outperform nonrobust designs as well as robust linear transceiver designs reported in the recent literature.

  11. Computer Simulation and Field Experiment for Downlink Multiuser MIMO in Mobile WiMAX System.

    PubMed

    Yamaguchi, Kazuhiro; Nagahashi, Takaharu; Akiyama, Takuya; Matsue, Hideaki; Uekado, Kunio; Namera, Takakazu; Fukui, Hiroshi; Nanamatsu, Satoshi

    2015-01-01

    The transmission performance for a downlink mobile WiMAX system with multiuser multiple-input multiple-output (MU-MIMO) systems in a computer simulation and field experiment is described. In computer simulation, a MU-MIMO transmission system can be realized by using the block diagonalization (BD) algorithm, and each user can receive signals without any signal interference from other users. The bit error rate (BER) performance and channel capacity in accordance with modulation schemes and the number of streams were simulated in a spatially correlated multipath fading environment. Furthermore, we propose a method for evaluating the transmission performance for this downlink mobile WiMAX system in this environment by using the computer simulation. In the field experiment, the received power and downlink throughput in the UDP layer were measured on an experimental mobile WiMAX system developed in Azumino City in Japan. In comparison with the simulated and experimented results, the measured maximum throughput performance in the downlink had almost the same performance as the simulated throughput. It was confirmed that the experimental mobile WiMAX system for MU-MIMO transmission successfully increased the total channel capacity of the system. PMID:26421311

  12. Astronaut Andrew M. Allen, mission commander, sets up systems for a television downlink on the

    NASA Technical Reports Server (NTRS)

    1996-01-01

    STS-75 ONBOARD VIEW --- Astronaut Andrew M. Allen, mission commander, sets up systems for a television downlink on the flight deck of the Space Shuttle Columbia. Allen was joined by four other astronauts and an international payload specialist for more than 16 days of research aboard Columbia. The photograph was taken with a 70mm handheld camera.

  13. Computer Simulation and Field Experiment for Downlink Multiuser MIMO in Mobile WiMAX System

    PubMed Central

    Yamaguchi, Kazuhiro; Nagahashi, Takaharu; Akiyama, Takuya; Matsue, Hideaki; Uekado, Kunio; Namera, Takakazu; Fukui, Hiroshi; Nanamatsu, Satoshi

    2015-01-01

    The transmission performance for a downlink mobile WiMAX system with multiuser multiple-input multiple-output (MU-MIMO) systems in a computer simulation and field experiment is described. In computer simulation, a MU-MIMO transmission system can be realized by using the block diagonalization (BD) algorithm, and each user can receive signals without any signal interference from other users. The bit error rate (BER) performance and channel capacity in accordance with modulation schemes and the number of streams were simulated in a spatially correlated multipath fading environment. Furthermore, we propose a method for evaluating the transmission performance for this downlink mobile WiMAX system in this environment by using the computer simulation. In the field experiment, the received power and downlink throughput in the UDP layer were measured on an experimental mobile WiMAX system developed in Azumino City in Japan. In comparison with the simulated and experimented results, the measured maximum throughput performance in the downlink had almost the same performance as the simulated throughput. It was confirmed that the experimental mobile WiMAX system for MU-MIMO transmission successfully increased the total channel capacity of the system. PMID:26421311

  14. Computer Simulation and Field Experiment for Downlink Multiuser MIMO in Mobile WiMAX System.

    PubMed

    Yamaguchi, Kazuhiro; Nagahashi, Takaharu; Akiyama, Takuya; Matsue, Hideaki; Uekado, Kunio; Namera, Takakazu; Fukui, Hiroshi; Nanamatsu, Satoshi

    2015-01-01

    The transmission performance for a downlink mobile WiMAX system with multiuser multiple-input multiple-output (MU-MIMO) systems in a computer simulation and field experiment is described. In computer simulation, a MU-MIMO transmission system can be realized by using the block diagonalization (BD) algorithm, and each user can receive signals without any signal interference from other users. The bit error rate (BER) performance and channel capacity in accordance with modulation schemes and the number of streams were simulated in a spatially correlated multipath fading environment. Furthermore, we propose a method for evaluating the transmission performance for this downlink mobile WiMAX system in this environment by using the computer simulation. In the field experiment, the received power and downlink throughput in the UDP layer were measured on an experimental mobile WiMAX system developed in Azumino City in Japan. In comparison with the simulated and experimented results, the measured maximum throughput performance in the downlink had almost the same performance as the simulated throughput. It was confirmed that the experimental mobile WiMAX system for MU-MIMO transmission successfully increased the total channel capacity of the system.

  15. Reduction of ETS-VI Laser Communication Equipment Optical-Downlink Telemetry Collected During GOLD

    NASA Technical Reports Server (NTRS)

    Toyoshima, M.; Araki, K.; Arimoto, Y.; Toyoda, M.; Jeganathan, M.; Wilson, K.; Lesh, J. R.

    1997-01-01

    Free-space laser communications experiments were conducted between the laser communication equipment (LCE) on board the Japanese Engineering Test Satellite VI (ETS-VI) and the ground station located at the Table Mountain Facility (TMF) during late 1995 and early 1996. This article describes the on-line data reduction process used to decode LCE telemetry (called E2) downlinked on the optical carrier during the Ground/Orbiter Lasercomm Demonstration (GOLD) experiments. The LCE has the capability of transmitting real-time sensor and status information at 128 kbps by modulating the onboard diode laser. The optical downlink was detected on the ground, bit synchronized, and the resulting data stream stored on a data recorder. The recorded data were subsequently decoded by on-line data processing that included cross-correlation of the known telemetry data format and the downlink data stream. Signals obtained from the processing can be useful not only in evaluating the characteristics of the LCE but also in understanding uplink and downlink signal quality.

  16. Uplink Downlink Rate Balancing and Throughput Scaling in FDD Massive MIMO Systems

    NASA Astrophysics Data System (ADS)

    Bergel, Itsik; Perets, Yona; Shamai, Shlomo

    2016-05-01

    In this work we extend the concept of uplink-downlink rate balancing to frequency division duplex (FDD) massive MIMO systems. We consider a base station with large number antennas serving many single antenna users. We first show that any unused capacity in the uplink can be traded off for higher throughput in the downlink in a system that uses either dirty paper (DP) coding or linear zero-forcing (ZF) precoding. We then also study the scaling of the system throughput with the number of antennas in cases of linear Beamforming (BF) Precoding, ZF Precoding, and DP coding. We show that the downlink throughput is proportional to the logarithm of the number of antennas. While, this logarithmic scaling is lower than the linear scaling of the rate in the uplink, it can still bring significant throughput gains. For example, we demonstrate through analysis and simulation that increasing the number of antennas from 4 to 128 will increase the throughput by more than a factor of 5. We also show that a logarithmic scaling of downlink throughput as a function of the number of receive antennas can be achieved even when the number of transmit antennas only increases logarithmically with the number of receive antennas.

  17. Joint minimization of uplink and downlink whole-body exposure dose in indoor wireless networks.

    PubMed

    Plets, D; Joseph, W; Vanhecke, K; Vermeeren, G; Wiart, J; Aerts, S; Varsier, N; Martens, L

    2015-01-01

    The total whole-body exposure dose in indoor wireless networks is minimized. For the first time, indoor wireless networks are designed and simulated for a minimal exposure dose, where both uplink and downlink are considered. The impact of the minimization is numerically assessed for four scenarios: two WiFi configurations with different throughputs, a Universal Mobile Telecommunications System (UMTS) configuration for phone call traffic, and a Long-Term Evolution (LTE) configuration with a high data rate. Also, the influence of the uplink usage on the total absorbed dose is characterized. Downlink dose reductions of at least 75% are observed when adding more base stations with a lower transmit power. Total dose reductions decrease with increasing uplink usage for WiFi due to the lack of uplink power control but are maintained for LTE and UMTS. Uplink doses become dominant over downlink doses for usages of only a few seconds for WiFi. For UMTS and LTE, an almost continuous uplink usage is required to have a significant effect on the total dose, thanks to the power control mechanism. PMID:25793213

  18. Joint Minimization of Uplink and Downlink Whole-Body Exposure Dose in Indoor Wireless Networks

    PubMed Central

    Plets, D.; Joseph, W.; Vanhecke, K.; Vermeeren, G.; Wiart, J.; Aerts, S.; Varsier, N.; Martens, L.

    2015-01-01

    The total whole-body exposure dose in indoor wireless networks is minimized. For the first time, indoor wireless networks are designed and simulated for a minimal exposure dose, where both uplink and downlink are considered. The impact of the minimization is numerically assessed for four scenarios: two WiFi configurations with different throughputs, a Universal Mobile Telecommunications System (UMTS) configuration for phone call traffic, and a Long-Term Evolution (LTE) configuration with a high data rate. Also, the influence of the uplink usage on the total absorbed dose is characterized. Downlink dose reductions of at least 75% are observed when adding more base stations with a lower transmit power. Total dose reductions decrease with increasing uplink usage for WiFi due to the lack of uplink power control but are maintained for LTE and UMTS. Uplink doses become dominant over downlink doses for usages of only a few seconds for WiFi. For UMTS and LTE, an almost continuous uplink usage is required to have a significant effect on the total dose, thanks to the power control mechanism. PMID:25793213

  19. Joint minimization of uplink and downlink whole-body exposure dose in indoor wireless networks.

    PubMed

    Plets, D; Joseph, W; Vanhecke, K; Vermeeren, G; Wiart, J; Aerts, S; Varsier, N; Martens, L

    2015-01-01

    The total whole-body exposure dose in indoor wireless networks is minimized. For the first time, indoor wireless networks are designed and simulated for a minimal exposure dose, where both uplink and downlink are considered. The impact of the minimization is numerically assessed for four scenarios: two WiFi configurations with different throughputs, a Universal Mobile Telecommunications System (UMTS) configuration for phone call traffic, and a Long-Term Evolution (LTE) configuration with a high data rate. Also, the influence of the uplink usage on the total absorbed dose is characterized. Downlink dose reductions of at least 75% are observed when adding more base stations with a lower transmit power. Total dose reductions decrease with increasing uplink usage for WiFi due to the lack of uplink power control but are maintained for LTE and UMTS. Uplink doses become dominant over downlink doses for usages of only a few seconds for WiFi. For UMTS and LTE, an almost continuous uplink usage is required to have a significant effect on the total dose, thanks to the power control mechanism.

  20. Downlink Specifications for GOES-R Direct Readout Users

    NASA Astrophysics Data System (ADS)

    Kalluri, S.; Race, R.; Reynolds, R. G.

    2012-12-01

    The next generation of Geostationary Operational Environmental Satellite (GOES R-series) is scheduled to be launched in 2015. GOES R-series (GOES-R, -S, -T, and -U) represents a generational change in both spacecraft and instrument capability, and will provide improved observations of earth and space weather compared to its predecessors. Raw data from the GOES-R instruments are received at the Wallops Command and Data Acquisition Station (WCDAS), or the Remote Back-Up (RBU) ground station in Fairmont, WV, and processed to L1b radiances for all instruments, as well as L2+ products from the Geostationary Lightning Mapper (GLM). This data from WCDAS/RBU will be re-broadcast as GOES Re-Broadcast (GRB) data to users with direct read out terminals within the hemispheric view of GOES in real time. GRB is the GOES-R version of today's GOES Variable (GVAR) data format, and will be transmitted at 15 times the data volume/rate of the current GVAR. All the GRB data will be broadcast as CCSDS packets in the DVB-S2 standard. GRB signal will be a dual circular polarized signal at a center frequency of 1686.6 Mhz. Direct broadcast users will have to upgrade existing ground processing equipment or procure new space to ground communication hardware to receive GRB, possibly including upgraded/new antenna systems. For terrestrial users, all GOES-R L1b and L2+ products will be distributed at low latency through the Product Distribution and Access (PDA) system, a part of NOAA's Environmental Satellite Processing and Distribution Center (ESPC). This presentation describes the characteristics of GRB data and specifications of the user receiver systems.

  1. Intrinsic interference mitigating coordinated beamforming for the FBMC/OQAM based downlink

    NASA Astrophysics Data System (ADS)

    Cheng, Yao; Li, Peng; Haardt, Martin

    2014-12-01

    In this work, we propose intrinsic interference mitigating coordinated beamforming (IIM-CBF)-based transmission strategies for the downlink of multi-user multiple-input-multiple-out (MIMO) systems and coordinated multi-point (CoMP) systems where filter bank based multi-carrier with offset quadrature amplitude modulation (FBMC/OQAM) is employed. Our goal is to alleviate the dimensionality constraint imposed on the state-of-the-art solutions for FBMC/OQAM-based space division multiple access that the total number of receive antennas of the users must not exceed the number of transmit antennas at the base station. First, two IIM-CBF algorithms are developed for a single-cell multi-user MIMO downlink system. The central idea is to jointly and iteratively calculate the precoding matrix and decoding matrix for each subcarrier to mitigate the multi-user interference as well as the intrinsic interference inherent in FBMC/OQAM-based systems. Second, for a CoMP downlink scenario where partial coordination among the base stations is considered, the application of coordinated beamforming-based transmission schemes is further investigated. An appropriate IIM-CBF technique is proposed. Simulation results show that when the number of transmit antennas at the base station is equal to the total number of receive antennas of the users, the proposed IIM-CBF algorithm outperforms the existing transmission strategies for FBMC/OQAM-based multi-user MIMO downlink systems. Moreover, we evaluate the performances of the IIM-CBF schemes in the downlink of multi-user MIMO systems and CoMP systems where the total number of receive antennas of users exceeds the number of transmit antennas at the base station. It is observed that by employing the IIM-CBF techniques, FBMC/OQAM systems achieve a similar bit error rate (BER) performance as its orthogonal frequency division multiplexing with the cyclic prefix insertion (CP-OFDM)-based counterpart while exhibiting superiority in terms of a higher

  2. Time-Asynchronous Robust Cooperative Transmission for the Downlink of C-RAN

    NASA Astrophysics Data System (ADS)

    Park, Seok-Hwan; Simeone, Osvaldo; Shitz, Shlomo Shamai

    2016-10-01

    This work studies the robust design of downlink precoding for cloud radio access network (C-RAN) in the presence of asynchronism among remote radio heads (RRHs). Specifically, a C-RAN downlink system is considered in which non-ideal fronthaul links connecting two RRHs to a Baseband Unit (BBU) may cause a time offset, as well as a phase offset, between the transmissions of the two RRHs. The offsets are a priori not known to the BBU. With the aim of counteracting the unknown time offset, a robust precoding scheme is considered that is based on the idea of correlating the signal transmitted by one RRH with a number of delayed versions of the signal transmitted by the other RRH. For this transmission strategy, the problem of maximizing the worst-case minimum rate is tackled while satisfying per-RRH transmit power constraints. Numerical results are reported that verify the advantages of the proposed robust scheme as compared to conventional non-robust design criteria as well as non-cooperative transmission.

  3. Optimized scheduling technique of null subcarriers for peak power control in 3GPP LTE downlink.

    PubMed

    Cho, Soobum; Park, Sang Kyu

    2014-01-01

    Orthogonal frequency division multiple access (OFDMA) is a key multiple access technique for the long term evolution (LTE) downlink. However, high peak-to-average power ratio (PAPR) can cause the degradation of power efficiency. The well-known PAPR reduction technique, dummy sequence insertion (DSI), can be a realistic solution because of its structural simplicity. However, the large usage of subcarriers for the dummy sequences may decrease the transmitted data rate in the DSI scheme. In this paper, a novel DSI scheme is applied to the LTE system. Firstly, we obtain the null subcarriers in single-input single-output (SISO) and multiple-input multiple-output (MIMO) systems, respectively; then, optimized dummy sequences are inserted into the obtained null subcarrier. Simulation results show that Walsh-Hadamard transform (WHT) sequence is the best for the dummy sequence and the ratio of 16 to 20 for the WHT and randomly generated sequences has the maximum PAPR reduction performance. The number of near optimal iteration is derived to prevent exhausted iterations. It is also shown that there is no bit error rate (BER) degradation with the proposed technique in LTE downlink system.

  4. Downlink power control in multi-code CDMA for mobile medicine.

    PubMed

    Lin, Chin-Feng; Chang, Wen-Thong; Lee, Hsin-Wang; Hung, Shih-Ii

    2006-05-01

    In this paper, we propose a downlink power-control mechanism to be applied in a multi-code code division multiple access (CDMA) mobile medicine system. The mobile medicine system can provide (i) measured blood pressure and body temperature, (ii) medical signals measured by the electrocardiogram (ECG) device, (iii) mobile patient's history, (iv) G.729 audio signals, (v) Joint Photographic Experts Group 2000 Medical images and Moving Picture Experts Group 4 charge-coupled device sensor video signals. By utilizing a multi-code CDMA spread spectrum communication system with downlink power-control strategy, it is possible for this system to meet the quality of service requirements of a mobile medicine network. In addition, such a system can maximize the resource utilization. For different messages to be sent, the power is controlled according to the requisite bit error rate (BER). Higher transmission power is given to the media with lower BER requirement. Numerical analysis shows that the ratios of transmission power for voice, video, and data virtual channels is approximately 1:2:13 when the BERs for voice, video, and data are 10(wedge)(- 3), 10(wedge)(- 4), and 10(wedge)(- 7), respectively. This power ratio is similar to the ratio of signal-to-noise plus interference power ratio for voice, video, and data during transmission. For the purpose of verifying the proposed argument, a simulation has been done and the results match the derivation very well.

  5. Optimized Scheduling Technique of Null Subcarriers for Peak Power Control in 3GPP LTE Downlink

    PubMed Central

    Park, Sang Kyu

    2014-01-01

    Orthogonal frequency division multiple access (OFDMA) is a key multiple access technique for the long term evolution (LTE) downlink. However, high peak-to-average power ratio (PAPR) can cause the degradation of power efficiency. The well-known PAPR reduction technique, dummy sequence insertion (DSI), can be a realistic solution because of its structural simplicity. However, the large usage of subcarriers for the dummy sequences may decrease the transmitted data rate in the DSI scheme. In this paper, a novel DSI scheme is applied to the LTE system. Firstly, we obtain the null subcarriers in single-input single-output (SISO) and multiple-input multiple-output (MIMO) systems, respectively; then, optimized dummy sequences are inserted into the obtained null subcarrier. Simulation results show that Walsh-Hadamard transform (WHT) sequence is the best for the dummy sequence and the ratio of 16 to 20 for the WHT and randomly generated sequences has the maximum PAPR reduction performance. The number of near optimal iteration is derived to prevent exhausted iterations. It is also shown that there is no bit error rate (BER) degradation with the proposed technique in LTE downlink system. PMID:24883376

  6. LEO-to-ground optical communications link using adaptive optics correction on the OPALS downlink

    NASA Astrophysics Data System (ADS)

    Wright, Malcolm W.; Kovalik, Joseph; Morris, Jeff; Abrahamson, Matthew; Biswas, Abhijit

    2016-03-01

    The Optical PAyload for Lasercomm Science (OPALS) experiment on the International Space Station (ISS) recently demonstrated successful optical downlinks to the NASA/JPL 1-m aperture telescope at the Optical Communication Telescope Laboratory (OCTL) located near Wrightwood, CA. A large area (200 μm diameter) free space coupled avalanche photodiode (APD) detector was used to receive video and a bit patterns at 50 Mb/s. We report on a recent experiment that used an adaptive optics system at OCTL to correct for atmospherically-induced refractive index fluctuations so that the downlink from the ISS could be coupled into a single mode fiber receiver. Stable fiber coupled power was achieved over an entire pass using a self-referencing interferometer based adaptive optics system that was provided and operated by Boeing Co. and integrated to OCTL. End-to-end transmission and reconstruction of an HD video signal verified the communication performance as in the original OPALS demonstration. Coupling the signal into a single mode fiber opens the possibility for higher bandwidth and efficiency modulation schemes and serves as a pilot experiment for future implementations.

  7. A Space-Time Signal Decomposition Algorithm for Downlink MIMO DS-CDMA Receivers

    NASA Astrophysics Data System (ADS)

    Wang, Yung-Yi; Fang, Wen-Hsien; Chen, Jiunn-Tsair

    We propose a dimension reduction algorithm for the receiver of the downlink of direct-sequence code-division multiple access (DS-CDMA) systems in which both the transmitters and the receivers employ antenna arrays of multiple elements. To estimate the high order channel parameters, we develop a layered architecture using dimension-reduced parameter estimation algorithms to estimate the frequency-selective multipath channels. In the proposed architecture, to exploit the space-time geometric characteristics of multipath channels, spatial beamformers and constrained (or unconstrained) temporal filters are adopted for clustered-multipath grouping and path isolation. In conjunction with the multiple access interference (MAI) suppression techniques, the proposed architecture jointly estimates the direction of arrivals, propagation delays, and fading amplitudes of the downlink fading multipaths. With the outputs of the proposed architecture, the signals of interest can then be naturally detected by using path-wise maximum ratio combining. Compared to the traditional techniques, such as the Joint-Angle-and-Delay-Estimation (JADE) algorithm for DOA-delay joint estimation and the space-time minimum mean square error (ST-MMSE) algorithm for signal detection, computer simulations show that the proposed algorithm substantially mitigate the computational complexity at the expense of only slight performance degradation.

  8. 47 CFR 27.19 - Requirements for operation of base and fixed stations in the 600 MHz downlink band in close...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... stations in the 600 MHz downlink band in close proximity to Radio Astronomy Observatories. 27.19 Section 27... base and fixed stations in the 600 MHz downlink band in close proximity to Radio Astronomy Observatories. (a) Licensees must make reasonable efforts to protect the radio astronomy observatory at...

  9. Performance of Multi-User Transmitter Pre-Processing Assisted Multi-Cell IDMA System for Downlink Transmission

    NASA Astrophysics Data System (ADS)

    Partibane, B.; Nagarajan, V.; Vishvaksenan, K. S.; Kalidoss, R.

    2015-06-01

    In this paper, we present the performance of multi-user transmitter pre-processing (MUTP) assisted coded-interleave division multiple access (IDMA) system over correlated frequency-selective channels for downlink communication. We realize MUTP using singular value decomposition (SVD) technique, which exploits the channel state information (CSI) of all the active users that is acquired via feedback channels. We consider the MUTP technique to alleviate the effects of co-channel interference (CCI) and multiple access interference (MAI). To be specific, we estimate the CSI using least square error (LSE) algorithm at each of the mobile stations (MSs) and perform vector quantization using Lloyd's algorithm, and feedback the bits that represents the quantized magnitudes and phases to the base station (BS) through the dedicated low rate noisy channel. Finally we recover the quantized bits at the BS to formulate the pre-processing matrix. The performance of MUTP aided IDMA systems are evaluated for five types of delay spread distributions pertaining to long-term evolution (LTE) and Stanford University Interim (SUI) channel models. We also compare the performance of MUTP with minimum mean square error (MMSE) detector for the coded IDMA system. The considered TP scheme alleviates the effects of CCI with less complex signal detection at the MSs when compared to MMSE detector. Further, our simulation results reveal that SVD-based MUTP assisted coded IDMA system outperforms the MMSE detector in terms of achievable bit error rate (BER) with low signal-to-noise ratio (SNR) requirement by mitigating the effects of CCI and MAI.

  10. Simple Laser Communications Terminal for Downlink from Earth Orbit at Rates Exceeding 10 Gb/s

    NASA Technical Reports Server (NTRS)

    Kovalik, Joseph M.; Hemmati, Hamid; Biswas, Abhijit; Roberts, William T.

    2013-01-01

    A compact, low-cost laser communications transceiver was prototyped for downlinking data at 10 Gb/s from Earth-orbiting spacecraft. The design can be implemented using flight-grade parts. With emphasis on simplicity, compactness, and light weight of the flight transceiver, the reduced-complexity design and development approach involves: 1. A high-bandwidth coarse wavelength division multiplexed (CWDM) (4 2.5 or 10-Gb/s data-rate) downlink transmitter. To simplify the system, emphasis is on the downlink. Optical uplink data rate is modest (due to existing and adequate RF uplink capability). 2. Highly simplified and compact 5-cm diameter clear aperture optics assembly is configured to single transmit and receive aperture laser signals. About 2 W of 4-channel multiplexed (1,540 to 1,555 nm) optically amplified laser power is coupled to the optical assembly through a fiber optic cable. It contains a highly compact, precision-pointing capability two-axis gimbal assembly to coarse point the optics assembly. A fast steering mirror, built into the optical path of the optical assembly, is used to remove residual pointing disturbances from the gimbal. Acquisition, pointing, and tracking are assisted by a beacon laser transmitted from the ground and received by the optical assembly, which will allow transmission of a laser beam. 3. Shifting the link burden to the ground by relying on direct detection optical receivers retrofitted to 1-m-diameter ground telescopes. 4. Favored mass and volume reduction over power-consumption reduction. The two major variables that are available include laser transmit power at either end of the link, and telescope aperture diameter at each end of the link. Increased laser power is traded for smaller-aperture diameters. 5. Use of commercially available spacequalified or qualifiable components with traceability to flight qualification (i.e., a flight-qualified version is commercially available). An example is use of Telecordia-qualified fiber

  11. Low-complexity user selection for rate maximization in MIMO broadcast channels with downlink beamforming.

    PubMed

    Castañeda, Eduardo; Silva, Adão; Samano-Robles, Ramiro; Gameiro, Atílio

    2014-01-01

    We present in this work a low-complexity algorithm to solve the sum rate maximization problem in multiuser MIMO broadcast channels with downlink beamforming. Our approach decouples the user selection problem from the resource allocation problem and its main goal is to create a set of quasiorthogonal users. The proposed algorithm exploits physical metrics of the wireless channels that can be easily computed in such a way that a null space projection power can be approximated efficiently. Based on the derived metrics we present a mathematical model that describes the dynamics of the user selection process which renders the user selection problem into an integer linear program. Numerical results show that our approach is highly efficient to form groups of quasiorthogonal users when compared to previously proposed algorithms in the literature. Our user selection algorithm achieves a large portion of the optimum user selection sum rate (90%) for a moderate number of active users.

  12. DS-CDMA satellite diversity reception for personal satellite communication: Downlink performance analysis

    NASA Technical Reports Server (NTRS)

    DeGaudenzi, Riccardo; Giannetti, Filippo

    1995-01-01

    The downlink of a satellite-mobile personal communication system employing power-controlled Direct Sequence Code Division Multiple Access (DS-CDMA) and exploiting satellite-diversity is analyzed and its performance compared with a more traditional communication system utilizing single satellite reception. The analytical model developed has been thoroughly validated by means of extensive Monte Carlo computer simulations. It is shown how the capacity gain provided by diversity reception shrinks considerably in the presence of increasing traffic or in the case of light shadowing conditions. Moreover, the quantitative results tend to indicate that to combat system capacity reduction due to intra-system interference, no more than two satellites shall be active over the same region. To achieve higher system capacity, differently from terrestrial cellular systems, Multi-User Detection (MUD) techniques are likely to be required in the mobile user terminal, thus considerably increasing its complexity.

  13. Building an Energy-efficient Uplink and Downlink Delay Aware TDM-PON System

    NASA Astrophysics Data System (ADS)

    Newaz, S. H. Shah; Jang, Min Seok; Alaelddin, Fuad Yousif Mohammed; Lee, Gyu Myoung; Choi, Jun Kyun

    2016-05-01

    With the increasing concern over the energy expenditure due to rapid ICT expansion and growth of Internet traffic volume, there is a growing trend towards developing energy-efficient ICT solutions. Passive Optical Network (PON), which is regarded as a key enabler to facilitate high speed broadband connection to individual subscribers, is considered as one of the energy-efficient access network technologies. However, an immense amount of research effort can be noticed in academia and industries to make PON more energy-efficient. In this paper, we aim at improving energy saving performance of Time Division Multiplexing (TDM)-PON, which is the most widely deployed PON technology throughout the world. A commonly used approach to make TDM-PON energy-efficient is to use sleep mode in Optical Network Units (ONUs), which are the customer premises equipment of a TDM-PON system. However, there is a strong trade-off relationship between traffic delay performance of an ONU and its energy saving (the longer the sleep interval length of an ONU, the lower its energy consumption, but the higher the traffic delay, and vice versa). In this paper, we propose an Energy-efficient Uplink and Downlink Delay Aware (EUDDA) scheme for TDM-PON system. The prime object of EUDDA is to meet both downlink and uplink traffic delay requirement while maximizing energy saving performance of ONUs as much as possible. In EUDDA, traffic delay requirement is given more priority over energy saving. Even so, it still can improve energy saving of ONUs noticeably. We evaluate performance of EUDDA in front of two existing solutions in terms of traffic delay, jitter, and ONU energy consumption. The performance results show that EUDDA significantly outperforms the other existing solutions.

  14. A full-duplex optical access system with hybrid 64/16/4QAM-OFDM downlink

    NASA Astrophysics Data System (ADS)

    He, Chao; Tan, Ze-fu; Shao, Yu-feng; Cai, Li; Pu, He-sheng; Zhu, Yun-le; Huang, Si-si; Liu, Yu

    2016-09-01

    A full-duplex optical passive access scheme is proposed and verified by simulation, in which hybrid 64/16/4-quadrature amplitude modulation (64/16/4QAM) orthogonal frequency division multiplexing (OFDM) optical signal is for downstream transmission and non-return-to-zero (NRZ) optical signal is for upstream transmission. In view of the transmitting and receiving process for downlink optical signal, in-phase/quadrature-phase (I/Q) modulation based on Mach-Zehnder modulator (MZM) and homodyne coherent detection technology are employed, respectively. The simulation results show that the bit error ratio ( BER) less than hardware decision forward error correction (HD-FEC) threshold is successfully obtained over transmission path with 20-km-long standard single mode fiber (SSMF) for hybrid downlink modulation OFDM optical signal. In addition, by dividing the system bandwidth into several subchannels consisting of some continuous subcarriers, it is convenient for users to select different channels depending on requirements of communication.

  15. A Downlink and Uplink Alignment Scheme for Power Saving in IEEE 802.16 Protocol

    PubMed Central

    2014-01-01

    This study shows the problem of power saving mechanism (PSM) that sleep intervals of uplink (UL) connections do not synchronize with sleep intervals of downlink (DL) connections. That is, the energy of a mobile station (MS) is not really saved if the DL connections are in the sleep mode while the UL connections are in normal mode, and vice versa. To avoid the asynchronism of power saving (PS) between UL and DL connections, we invent a mechanism of DL connections regulating UL connections, called DL and UL Alignment (DUAL) scheme, to improve the energy efficiency for PS. Considering that the buffer size of MS is limited, DUAL uses the mean packet arrival rate of UL λu and a relatively safe threshold of buffer size QT as the parameters to estimate the maximum allowable waiting time to align the UL with the DL connections. To analyze the performance of DUAL, a system model of PS is proposed to evaluate the performance of DUAL under different conditions. The correctness of performance analysis of DUAL is validated by using simulation with realistic parameters. Numerical experiments show that DUAL improves the energy conservation significantly when UL traffic is greater than DL traffic. PMID:24526884

  16. A downlink and uplink alignment scheme for power saving in IEEE 802.16 protocol.

    PubMed

    Chen, Jenhui; Tarn, Woei-Hwa; Lee, Jiann-Der

    2014-01-01

    This study shows the problem of power saving mechanism (PSM) that sleep intervals of uplink (UL) connections do not synchronize with sleep intervals of downlink (DL) connections. That is, the energy of a mobile station (MS) is not really saved if the DL connections are in the sleep mode while the UL connections are in normal mode, and vice versa. To avoid the asynchronism of power saving (PS) between UL and DL connections, we invent a mechanism of DL connections regulating UL connections, called DL and UL Alignment (DUAL) scheme, to improve the energy efficiency for PS. Considering that the buffer size of MS is limited, DUAL uses the mean packet arrival rate of UL λ u and a relatively safe threshold of buffer size Q T as the parameters to estimate the maximum allowable waiting time to align the UL with the DL connections. To analyze the performance of DUAL, a system model of PS is proposed to evaluate the performance of DUAL under different conditions. The correctness of performance analysis of DUAL is validated by using simulation with realistic parameters. Numerical experiments show that DUAL improves the energy conservation significantly when UL traffic is greater than DL traffic.

  17. A Wideband Satcom Based Avionics Network with CDMA Uplink and TDM Downlink

    NASA Technical Reports Server (NTRS)

    Agrawal, D.; Johnson, B. S.; Madhow, U.; Ramchandran, K.; Chun, K. S.

    2000-01-01

    The purpose of this paper is to describe some key technical ideas behind our vision of a future satcom based digital communication network for avionics applications The key features of our design are as follows: (a) Packetized transmission to permit efficient use of system resources for multimedia traffic; (b) A time division multiplexed (TDM) satellite downlink whose physical layer is designed to operate the satellite link at maximum power efficiency. We show how powerful turbo codes (invented originally for linear modulation) can be used with nonlinear constant envelope modulation, thus permitting the satellite amplifier to operate in a power efficient nonlinear regime; (c) A code division multiple access (CDMA) satellite uplink, which permits efficient access to the satellite from multiple asynchronous users. Closed loop power control is difficult for bursty packetized traffic, especially given the large round trip delay to the satellite. We show how adaptive interference suppression techniques can be used to deal with the ensuing near-far problem; (d) Joint source-channel coding techniques are required both at the physical and the data transport layer to optimize the end-to-end performance. We describe a novel approach to multiple description image encoding at the data transport layer in this paper.

  18. Coordinate Update Algorithms for Robust Power Loading for the MU-MISO Downlink With Outage Constraints

    NASA Astrophysics Data System (ADS)

    Sohrabi, Foad; Davidson, Timothy N.

    2016-06-01

    We consider the problem of power allocation for the single-cell multi-user (MU) multiple-input single-output (MISO) downlink with quality-of-service (QoS) constraints. The base station acquires an estimate of the channels and, for a given beamforming structure, designs the power allocation so as to minimize the total transmission power required to ensure that target signal-to-interference-and-noise ratios at the receivers are met, subject to a specified outage probability. We consider scenarios in which the errors in the base station's channel estimates can be modelled as being zero-mean and Gaussian. Such a model is particularly suitable for time division duplex (TDD) systems with quasi-static channels, in which the base station estimates the channel during the uplink phase. Under that model, we employ a precise deterministic characterization of the outage probability to transform the chance-constrained formulation to a deterministic one. Although that deterministic formulation is not convex, we develop a coordinate descent algorithm that can be shown to converge to a globally optimal solution when the starting point is feasible. Insight into the structure of the deterministic formulation yields approximations that result in coordinate update algorithms with good performance and significantly lower computational cost. The proposed algorithms provide better performance than existing robust power loading algorithms that are based on tractable conservative approximations, and can even provide better performance than robust precoding algorithms based on such approximations.

  19. Blind Adaptive Decorrelating RAKE (DRAKE) Downlink Receiver for Space-Time Block Coded Multipath CDMA

    NASA Astrophysics Data System (ADS)

    Jayaweera, Sudharman K.; Poor, H. Vincent

    2003-12-01

    A downlink receiver is proposed for space-time block coded CDMA systems operating in multipath channels. By combining the powerful RAKE receiver concept for a frequency selective channel with space-time decoding, it is shown that the performance of mobile receivers operating in the presence of channel fading can be improved significantly. The proposed receiver consists of a bank of decorrelating filters designed to suppress the multiple access interference embedded in the received signal before the space-time decoding. The new receiver performs the space-time decoding along each resolvable multipath component and then the outputs are diversity combined to obtain the final decision statistic. The proposed receiver relies on a key constraint imposed on the output of each filter in the bank of decorrelating filters in order to maintain the space-time block code structure embedded in the signal. The proposed receiver can easily be adapted blindly, requiring only the desired user's signature sequence, which is also attractive in the context of wireless mobile communications. Simulation results are provided to confirm the effectiveness of the proposed receiver in multipath CDMA systems.

  20. Two-Level Scheduling for Video Transmission over Downlink OFDMA Networks.

    PubMed

    Tham, Mau-Luen; Chow, Chee-Onn; Xu, Yi-Han; Ramli, Nordin

    2016-01-01

    This paper presents a two-level scheduling scheme for video transmission over downlink orthogonal frequency-division multiple access (OFDMA) networks. It aims to maximize the aggregate quality of the video users subject to the playback delay and resource constraints, by exploiting the multiuser diversity and the video characteristics. The upper level schedules the transmission of video packets among multiple users based on an overall target bit-error-rate (BER), the importance level of packet and resource consumption efficiency factor. Instead, the lower level renders unequal error protection (UEP) in terms of target BER among the scheduled packets by solving a weighted sum distortion minimization problem, where each user weight reflects the total importance level of the packets that has been scheduled for that user. Frequency-selective power is then water-filled over all the assigned subcarriers in order to leverage the potential channel coding gain. Realistic simulation results demonstrate that the proposed scheme significantly outperforms the state-of-the-art scheduling scheme by up to 6.8 dB in terms of peak-signal-to-noise-ratio (PSNR). Further test evaluates the suitability of equal power allocation which is the common assumption in the literature. PMID:26906398

  1. Two-Level Scheduling for Video Transmission over Downlink OFDMA Networks

    PubMed Central

    Tham, Mau-Luen

    2016-01-01

    This paper presents a two-level scheduling scheme for video transmission over downlink orthogonal frequency-division multiple access (OFDMA) networks. It aims to maximize the aggregate quality of the video users subject to the playback delay and resource constraints, by exploiting the multiuser diversity and the video characteristics. The upper level schedules the transmission of video packets among multiple users based on an overall target bit-error-rate (BER), the importance level of packet and resource consumption efficiency factor. Instead, the lower level renders unequal error protection (UEP) in terms of target BER among the scheduled packets by solving a weighted sum distortion minimization problem, where each user weight reflects the total importance level of the packets that has been scheduled for that user. Frequency-selective power is then water-filled over all the assigned subcarriers in order to leverage the potential channel coding gain. Realistic simulation results demonstrate that the proposed scheme significantly outperforms the state-of-the-art scheduling scheme by up to 6.8 dB in terms of peak-signal-to-noise-ratio (PSNR). Further test evaluates the suitability of equal power allocation which is the common assumption in the literature. PMID:26906398

  2. Tri-state delta modulation system for Space Shuttle digital TV downlink

    NASA Technical Reports Server (NTRS)

    Udalov, S.; Huth, G. K.; Roberts, D.; Batson, B. H.

    1981-01-01

    Future requirements for Shuttle Orbiter downlink communication may include transmission of digital video which, in addition to black and white, may also be either field-sequential or NTSC color format. The use of digitized video could provide for picture privacy at the expense of additional onboard hardware, together with an increased bandwidth due to the digitization process. A general objective for the Space Shuttle application is to develop a digitization technique that is compatible with data rates in the 20-30 Mbps range but still provides good quality pictures. This paper describes a tri-state delta modulation/demodulation (TSDM) technique which is a good compromise between implementation complexity and performance. The unique feature of TSDM is that it provides for efficient run-length encoding of constant-intensity segments of a TV picture. Axiomatix has developed a hardware implementation of a high-speed TSDM transmitter and receiver for black-and-white TV and field-sequential color. The hardware complexity of this TSDM implementation is summarized in the paper.

  3. An Efficient Circulant MIMO Equalizer for CDMA Downlink: Algorithm and VLSI Architecture

    NASA Astrophysics Data System (ADS)

    Guo, Yuanbin; Zhang, Jianzhong(Charlie); McCain, Dennis; Cavallaro, Joseph R.

    2006-12-01

    We present an efficient circulant approximation-based MIMO equalizer architecture for the CDMA downlink. This reduces the direct matrix inverse (DMI) of size[InlineEquation not available: see fulltext.] with[InlineEquation not available: see fulltext.] complexity to some FFT operations with[InlineEquation not available: see fulltext.] complexity and the inverse of some[InlineEquation not available: see fulltext.] submatrices. We then propose parallel and pipelined VLSI architectures with Hermitian optimization and reduced-state FFT for further complexity optimization. Generic VLSI architectures are derived for the[InlineEquation not available: see fulltext.] high-order receiver from partitioned[InlineEquation not available: see fulltext.] submatrices. This leads to more parallel VLSI design with[InlineEquation not available: see fulltext.] further complexity reduction. Comparative study with both the conjugate-gradient and DMI algorithms shows very promising performance/complexity tradeoff. VLSI design space in terms of area/time efficiency is explored extensively for layered parallelism and pipelining with a Catapult C high-level-synthesis methodology.

  4. On the Multiuser Diversity of Relay-Aided Downlink Systems Using Reduced Feedback

    PubMed Central

    2014-01-01

    We introduce an efficient multiuser scheduling method using amplify-and-forward relaying in relay-aided downlink systems, consisting of one base station (BS), one relay station, and multiple mobile stations (MSs). In our scheme, the BS opportunistically selects both the transmission mode, that is, either one- or two-hop transmission, and the desired user (i.e., the desired MS). Closed-form expressions for the average achievable rates are derived for the two transmission modes with multiuser scheduling, and its asymptotic solutions are also analyzed in the limit of large number of MSs. Based on the analysis, we propose a feedback-efficient two-step multiuser scheduling algorithm: the transmission mode selection followed by the user selection that only needs a partial feedback for instantaneous signal-to-noise ratios (SNRs) to the BS. We also analyze the average SNR condition such that the multiuser diversity gain is fully exploited for two-hop transmission. The proposed two-step scheduling algorithm exhibits the quite comparable achievable rates to those of the optimal one using full feedback information, while its required feedback information is reduced by half of the optimal one. PMID:25436232

  5. Amplitude Scintillation due to Atmospheric Turbulence for the Deep Space Network Ka-Band Downlink

    NASA Technical Reports Server (NTRS)

    Ho, C.; Wheelon, A.

    2004-01-01

    Fast amplitude variations due to atmospheric scintillation are the main concerns for the Deep Space Network (DSN) Ka-band downlink under clear weather conditions. A theoretical study of the amplitude scintillation variances for a finite aperture antenna is presented. Amplitude variances for weak scattering scenarios are examined using turbulence theory to describe atmospheric irregularities. We first apply the Kolmogorov turbulent spectrum to a point receiver for three different turbulent profile models, especially for an exponential model varying with altitude. These analytic solutions then are extended to a receiver with a finite aperture antenna for the three profile models. Smoothing effects of antenna aperture are expressed by gain factors. A group of scaling factor relations is derived to show the dependences of amplitude variances on signal wavelength, antenna size, and elevation angle. Finally, we use these analytic solutions to estimate the scintillation intensity for a DSN Goldstone 34-m receiving station. We find that the (rms) amplitude fluctuation is 0.13 dB at 20-deg elevation angle for an exponential model, while the fluctuation is 0.05 dB at 90 deg. These results will aid us in telecommunication system design and signal-fading prediction. They also provide a theoretical basis for further comparison with other measurements at Ka-band.

  6. Development and experimental validation of downlink multiuser MIMO-OFDM in gigabit wireless LAN systems

    NASA Astrophysics Data System (ADS)

    Ishihara, Koichi; Asai, Yusuke; Kudo, Riichi; Ichikawa, Takeo; Takatori, Yasushi; Mizoguchi, Masato

    2013-12-01

    Multiuser multiple-input multiple-output (MU-MIMO) has been proposed as a means to improve spectrum efficiency for various future wireless communication systems. This paper reports indoor experimental results obtained for a newly developed and implemented downlink (DL) MU-MIMO orthogonal frequency division multiplexing (OFDM) transceiver for gigabit wireless local area network systems in the microwave band. In the transceiver, the channel state information (CSI) is estimated at each user and fed back to an access point (AP) on a real-time basis. At the AP, the estimated CSI is used to calculate the transmit beamforming weight for DL MU-MIMO transmission. This paper also proposes a recursive inverse matrix computation scheme for computing the transmit weight in real time. Experiments with the developed transceiver demonstrate its feasibility in a number of indoor scenarios. The experimental results clarify that DL MU-MIMO-OFDM transmission can achieve a 972-Mbit/s transmission data rate with simple digital signal processing of single-antenna users in an indoor environment.

  7. Overcoming CubeSat downlink limits with vitamin: A new variable coded modulation protocol

    NASA Astrophysics Data System (ADS)

    Sielicki, Thomas A.

    Many space missions, including low earth orbit CubeSats, communicate in a highly dynamic environment because of variations in geometry, weather, and interference. At the same time, most missions communicate using fixed channel codes, modulations, and symbol rates, resulting in a constant data rate that does not adapt to the dynamic conditions. When conditions are good, the fixed date rate can be far below the theoretical maximum, called the Shannon limit; when conditions are bad, the fixed data rate may not work at all. To move beyond these fixed communications and achieve higher total data volume from emerging high-tech instruments, this thesis investigates the use of error correcting codes and different modulations. Variable coded modulation (VCM) takes advantage of the dynamic link by transmitting more information when the signal-to-noise ratio (SNR) is high. Likewise, VCM can throttle down the information rate when SNR is low without having to stop all communications. VCM outperforms fixed communications which can only operate at a fixed information rate as long as a certain signal threshold is met. This thesis presents a new VCM protocol and tests its performance in both software and hardware simulations. The protocol is geared towards CubeSat downlinks as complexity is focused in the receiver, while the transmission operations are kept simple. This thesis explores bin-packing as a way to optimize the selection of VCM modes based on expected SNR levels over time. Working end-to-end simulations were created using MATLAB and LabVIEW, while the hardware simulations were done with software defined radios. Results show that a CubeSat using VCM communications will deliver twice the data throughput of a fixed communications system.

  8. Investigation of the phase fluctuation effect on the BER performance of DPSK space downlink optical communication system on fluctuation channel

    NASA Astrophysics Data System (ADS)

    Li, Mi; Li, Bowen; Zhang, Xuping; Song, Yuejiang; Chang, Lingqian; Chen, Yuan

    2016-05-01

    Phase fluctuation effect is an important phenomenon on bit error rate (BER) performance on fluctuation channel in space downlink optical communication system. During research process, both intensity scintillation and phase fluctuation caused by atmospheric turbulence have been considered on fluctuation channel. Through the analysis of simulation results, the influence of phase fluctuation is not sensitive for wavelength and APD gain factor at high data rate. Besides, receiving diameter and divergence angle can be adjusted properly in order to obtain optimal BER performance. This work is helpful to the research of phase fluctuation and the design of practical system.

  9. Effects of fade distribution on a mobile satellite downlink and uplink performance in a frequency reuse cellular configuration

    NASA Technical Reports Server (NTRS)

    Boutin, Karl; Lecours, Michel; Pelletier, Marcel; Delisle, Gilles Y.

    1990-01-01

    In a mobile satellite system with a frequency reuse cellular configuration, significant co-channel interference can be experienced due to the antenna sidelobe level. The signal will be subjected not only to its own fading, but also to the effect of the varying degree of fading on co-channel interferer, and this interference will behave differently in the up and in the down link. This paper presents a quantitative evaluation of the combined effects of fades and co-channel interference on a mobile satellite link.

  10. Downlink Training Techniques for FDD Massive MIMO Systems: Open-Loop and Closed-Loop Training With Memory

    NASA Astrophysics Data System (ADS)

    Choi, Junil; Love, David J.; Bidigare, Patrick

    2014-10-01

    The concept of deploying a large number of antennas at the base station, often called massive multiple-input multiple-output (MIMO), has drawn considerable interest because of its potential ability to revolutionize current wireless communication systems. Most literature on massive MIMO systems assumes time division duplexing (TDD), although frequency division duplexing (FDD) dominates current cellular systems. Due to the large number of transmit antennas at the base station, currently standardized approaches would require a large percentage of the precious downlink and uplink resources in FDD massive MIMO be used for training signal transmissions and channel state information (CSI) feedback. To reduce the overhead of the downlink training phase, we propose practical open-loop and closed-loop training frameworks in this paper. We assume the base station and the user share a common set of training signals in advance. In open-loop training, the base station transmits training signals in a round-robin manner, and the user successively estimates the current channel using long-term channel statistics such as temporal and spatial correlations and previous channel estimates. In closed-loop training, the user feeds back the best training signal to be sent in the future based on channel prediction and the previously received training signals. With a small amount of feedback from the user to the base station, closed-loop training offers better performance in the data communication phase, especially when the signal-to-noise ratio is low, the number of transmit antennas is large, or prior channel estimates are not accurate at the beginning of the communication setup, all of which would be mostly beneficial for massive MIMO systems.

  11. Adaptive optics correction into single mode fiber for a low Earth orbiting space to ground optical communication link using the OPALS downlink.

    PubMed

    Wright, Malcolm W; Morris, Jeffery F; Kovalik, Joseph M; Andrews, Kenneth S; Abrahamson, Matthew J; Biswas, Abhijit

    2015-12-28

    An adaptive optics (AO) testbed was integrated to the Optical PAyload for Lasercomm Science (OPALS) ground station telescope at the Optical Communications Telescope Laboratory (OCTL) as part of the free space laser communications experiment with the flight system on board the International Space Station (ISS). Atmospheric turbulence induced aberrations on the optical downlink were adaptively corrected during an overflight of the ISS so that the transmitted laser signal could be efficiently coupled into a single mode fiber continuously. A stable output Strehl ratio of around 0.6 was demonstrated along with the recovery of a 50 Mbps encoded high definition (HD) video transmission from the ISS at the output of the single mode fiber. This proof of concept demonstration validates multi-Gbps optical downlinks from fast slewing low-Earth orbiting (LEO) spacecraft to ground assets in a manner that potentially allows seamless space to ground connectivity for future high data-rates network. PMID:26832033

  12. Adaptive optics correction into single mode fiber for a low Earth orbiting space to ground optical communication link using the OPALS downlink.

    PubMed

    Wright, Malcolm W; Morris, Jeffery F; Kovalik, Joseph M; Andrews, Kenneth S; Abrahamson, Matthew J; Biswas, Abhijit

    2015-12-28

    An adaptive optics (AO) testbed was integrated to the Optical PAyload for Lasercomm Science (OPALS) ground station telescope at the Optical Communications Telescope Laboratory (OCTL) as part of the free space laser communications experiment with the flight system on board the International Space Station (ISS). Atmospheric turbulence induced aberrations on the optical downlink were adaptively corrected during an overflight of the ISS so that the transmitted laser signal could be efficiently coupled into a single mode fiber continuously. A stable output Strehl ratio of around 0.6 was demonstrated along with the recovery of a 50 Mbps encoded high definition (HD) video transmission from the ISS at the output of the single mode fiber. This proof of concept demonstration validates multi-Gbps optical downlinks from fast slewing low-Earth orbiting (LEO) spacecraft to ground assets in a manner that potentially allows seamless space to ground connectivity for future high data-rates network.

  13. Exposure assessment of one-year-old child to 3G tablet in uplink mode and to 3G femtocell in downlink mode using polynomial chaos decomposition

    NASA Astrophysics Data System (ADS)

    Liorni, I.; Parazzini, M.; Varsier, N.; Hadjem, A.; Ravazzani, P.; Wiart, J.

    2016-04-01

    So far, the assessment of the exposure of children, in the ages 0-2 years old, to relatively new radio-frequency (RF) technologies, such as tablets and femtocells, remains an open issue. This study aims to analyse the exposure of a one year-old child to these two sources, tablets and femtocells, operating in uplink (tablet) and downlink (femtocell) modes, respectively. In detail, a realistic model of an infant has been used to model separately the exposures due to (i) a 3G tablet emitting at the frequency of 1940 MHz (uplink mode) placed close to the body and (ii) a 3G femtocell emitting at 2100 MHz (downlink mode) placed at a distance of at least 1 m from the infant body. For both RF sources, the input power was set to 250 mW. The variability of the exposure due to the variation of the position of the RF sources with respect to the infant body has been studied by stochastic dosimetry, based on polynomial chaos to build surrogate models of both whole-body and tissue specific absorption rate (SAR), which makes it easy and quick to investigate the exposure in a full range of possible positions of the sources. The major outcomes of the study are: (1) the maximum values of the whole-body SAR (WB SAR) have been found to be 9.5 mW kg-1 in uplink mode and 65 μW kg-1 in downlink mode, i.e. within the limits of the ICNIRP 1998 Guidelines; (2) in both uplink and downlink mode the highest SAR values were approximately found in the same tissues, i.e. in the skin, eye and penis for the whole-tissue SAR and in the bone, skin and muscle for the peak SAR; (3) the change in the position of both the 3G tablet and the 3G femtocell significantly influences the infant exposure.

  14. Exposure assessment of one-year-old child to 3G tablet in uplink mode and to 3G femtocell in downlink mode using polynomial chaos decomposition.

    PubMed

    Liorni, I; Parazzini, M; Varsier, N; Hadjem, A; Ravazzani, P; Wiart, J

    2016-04-21

    So far, the assessment of the exposure of children, in the ages 0-2 years old, to relatively new radio-frequency (RF) technologies, such as tablets and femtocells, remains an open issue. This study aims to analyse the exposure of a one year-old child to these two sources, tablets and femtocells, operating in uplink (tablet) and downlink (femtocell) modes, respectively. In detail, a realistic model of an infant has been used to model separately the exposures due to (i) a 3G tablet emitting at the frequency of 1940 MHz (uplink mode) placed close to the body and (ii) a 3G femtocell emitting at 2100 MHz (downlink mode) placed at a distance of at least 1 m from the infant body. For both RF sources, the input power was set to 250 mW. The variability of the exposure due to the variation of the position of the RF sources with respect to the infant body has been studied by stochastic dosimetry, based on polynomial chaos to build surrogate models of both whole-body and tissue specific absorption rate (SAR), which makes it easy and quick to investigate the exposure in a full range of possible positions of the sources. The major outcomes of the study are: (1) the maximum values of the whole-body SAR (WB SAR) have been found to be 9.5 mW kg(-1) in uplink mode and 65 μW kg(-1) in downlink mode, i.e. within the limits of the ICNIRP 1998 Guidelines; (2) in both uplink and downlink mode the highest SAR values were approximately found in the same tissues, i.e. in the skin, eye and penis for the whole-tissue SAR and in the bone, skin and muscle for the peak SAR; (3) the change in the position of both the 3G tablet and the 3G femtocell significantly influences the infant exposure.

  15. Video distribution system cost model

    NASA Technical Reports Server (NTRS)

    Gershkoff, I.; Haspert, J. K.; Morgenstern, B.

    1980-01-01

    A cost model that can be used to systematically identify the costs of procuring and operating satellite linked communications systems is described. The user defines a network configuration by specifying the location of each participating site, the interconnection requirements, and the transmission paths available for the uplink (studio to satellite), downlink (satellite to audience), and voice talkback (between audience and studio) segments of the network. The model uses this information to calculate the least expensive signal distribution path for each participating site. Cost estimates are broken downy by capital, installation, lease, operations and maintenance. The design of the model permits flexibility in specifying network and cost structure.

  16. Downlink data multiplexer

    NASA Technical Reports Server (NTRS)

    Holland, S. Douglas (Inventor); Steele, Glen F. (Inventor); Romero, Denise M. (Inventor); Koudelka, Robert David (Inventor)

    2008-01-01

    A data multiplexer that accommodates both industry standard CCSDS data packets and bits streams and standard IEEE 1394 data is described. The multiplexer provides a statistical allotment of bandwidth to the channels in turn, preferably four, but expandable in increments of four up to sixteen. A microcontroller determines bandwidth requested by the plurality of channels, as well as the bandwidth available, and meters out the available bandwidth on a statistical basis employing flow control to the input channels.

  17. Long-term exposure to mobile communication radiation: an analysis of time-variability of electric field level in GSM900 downlink channels.

    PubMed

    Miclaus, Simona; Bechet, Paul; Gheorghevici, Marius

    2013-04-01

    Interest for knowing long-term human exposure levels due to mobile communications has increased in the last years. It has been shown that short-term exposure assessment made under standard procedural restrictions is not reliable when it comes to conclusions on long-term exposure levels. The present work is the result of a several week analysis of time variability of electric field level inside traffic and control channels of the GSM900 mobile communication downlink band and it indicates that a temporal model to allow future predictions of exposure on the long run is obtainable. Collecting, processing and statistically analysing the data provide expression of the maximum and weighted field strengths and their evolution in time. Specific electromagnetic footprints of the channels have been extracted, differentiations between their characteristics have been emphasised and practical advice is provided, with the scope of contributing to the development of reliable procedures for long-term exposure assessment.

  18. Portable color multimedia training systems based on monochrome laptop computers (CBT-in-a-briefcase), with spinoff implications for video uplink and downlink in spaceflight operations

    NASA Technical Reports Server (NTRS)

    Scott, D. W.

    1994-01-01

    This report describes efforts to use digital motion video compression technology to develop a highly portable device that would convert 1990-91 era IBM-compatible and/or MacIntosh notebook computers into full-color, motion-video capable multimedia training systems. An architecture was conceived that would permit direct conversion of existing laser-disk-based multimedia courses with little or no reauthoring. The project did not physically demonstrate certain critical video keying techniques, but their implementation should be feasible. This investigation of digital motion video has spawned two significant spaceflight projects at MSFC: one to downlink multiple high-quality video signals from Spacelab, and the other to uplink videoconference-quality video in realtime and high quality video off-line, plus investigate interactive, multimedia-based techniques for enhancing onboard science operations. Other airborne or spaceborne spinoffs are possible.

  19. National Space Transportation System telemetry distribution and processing, NASA-JFK Space Center/Cape Canaveral

    NASA Technical Reports Server (NTRS)

    Jenkins, George

    1986-01-01

    Prelaunch, launch, mission, and landing distribution of RF and hardline uplink/downlink information between Space Shuttle Orbiter/cargo elements, tracking antennas, and control centers at JSC, KSC, MSFC, GSFC, ESMC/RCC, and Sunnyvale are presented as functional block diagrams. Typical mismatch problems encountered during spacecraft-to-project control center telemetry transmissions are listed along with new items for future support enhancement.

  20. National Space Transportation System telemetry distribution and processing, NASA-JFK Space Center/Cape Canaveral

    NASA Astrophysics Data System (ADS)

    Jenkins, George

    Prelaunch, launch, mission, and landing distribution of RF and hardline uplink/downlink information between Space Shuttle Orbiter/cargo elements, tracking antennas, and control centers at JSC, KSC, MSFC, GSFC, ESMC/RCC, and Sunnyvale are presented as functional block diagrams. Typical mismatch problems encountered during spacecraft-to-project control center telemetry transmissions are listed along with new items for future support enhancement.

  1. Distributed Operations Planning

    NASA Technical Reports Server (NTRS)

    Fox, Jason; Norris, Jeffrey; Powell, Mark; Rabe, Kenneth; Shams, Khawaja

    2007-01-01

    Maestro software provides a secure and distributed mission planning system for long-term missions in general, and the Mars Exploration Rover Mission (MER) specifically. Maestro, the successor to the Science Activity Planner, has a heavy emphasis on portability and distributed operations, and requires no data replication or expensive hardware, instead relying on a set of services functioning on JPL institutional servers. Maestro works on most current computers with network connections, including laptops. When browsing down-link data from a spacecraft, Maestro functions similarly to being on a Web browser. After authenticating the user, it connects to a database server to query an index of data products. It then contacts a Web server to download and display the actual data products. The software also includes collaboration support based upon a highly reliable messaging system. Modifications made to targets in one instance are quickly and securely transmitted to other instances of Maestro. The back end that has been developed for Maestro could benefit many future missions by reducing the cost of centralized operations system architecture.

  2. Distributed joint power and access control algorithm for secondary spectrum sharing

    NASA Astrophysics Data System (ADS)

    Li, Hongyan; Chen, Enqing; Fu, Hongliang

    2010-08-01

    Based on interference temperature model, the problem of efficient secondary spectrum sharing is formulated as a power optimization problem with some constraints at physical layer. These constraints and optimization objective limit a feasible power vector set which leads to the need of access control besides power control. In this paper, we consider the decentralized cognitive radio network scenario where short-term data service is required, and the problem of distributed joint power and access control is studied to maximize the total secondary system throughput, subject to Quality of Service (QoS) constraints from individual secondary users and interference temperature limit (ITL) from primary system. Firstly, a pricing-based game model was used to solve distributed power allocation optimization problem in both high and low signal to interference noise ratio (SINR) scenarios. Secondly, when not all the secondary links can be supported with their QoS requirement and ITL, a distributed joint power and access control algorithm was introduced to find the allowable links which results in maximum network throughput with all the constraints satisfied, and the convergence performance is tested by simulations.

  3. Architecture Studies Done for High-Rate Duplex Direct Data Distribution (D4) Services

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A study was sponsored to investigate a set of end-to-end system concepts for implementing a high-rate duplex direct data distribution (D4) space-to-ground communications link. The NASA Glenn Research Center is investigating these systems (both commercial and Government) as a possible method of providing a D4 communications service between NASA spacecraft in low Earth orbit and the respective principal investigators using or monitoring instruments aboard these spacecraft. Candidate commercial services were assessed regarding their near-term potential to provide a D4 type of service. The candidates included K-band and V-band geostationary orbit and nongeostationary orbit satellite relay services and direct downlink (D3) services. Internet protocol (IP) networking technologies were evaluated to enable the user-directed distribution and delivery of science data. Four realistic, near-future concepts were analyzed: 1) A duplex direct link (uplink plus downlink communication paths) between a low-Earth-orbit spacecraft and a principal-investigator-based autonomous Earth station; 2) A space-based relay using a future K-band nongeosynchronous-orbit system to handle both the uplink and downlink communication paths; 3) A hybrid link using both direct and relay services to achieve full duplex capability; 4) A dual-mode concept consisting of both a duplex direct link and a space relay duplex link operating independently. The concepts were analyzed in terms of contact time between the NASA spacecraft and the communications service and the achievable data throughput. Throughput estimates for the D4 systems were based on the infusion of advanced communications technology products (single and multibeam K-band phased-arrays and digital modems) being developed by Glenn. Cost estimates were also performed using extrapolated information from both terrestrial and current satellite communications providers. The throughput and cost estimates were used to compare the concepts.

  4. Duplex Direct Data Distribution System

    NASA Technical Reports Server (NTRS)

    Greenfield, Israel (Technical Monitor)

    2001-01-01

    The NASA Glenn Research Center (GRC) is developing and demonstrating communications and network technologies that are helping to enable the near-Earth space Internet. GRC envisions several service categories. The first of these categories is direct data distribution or D3 (pronounced "D-cubed"). Commercially provided D3 will make it possible to download a data set from a spacecraft, like the International Space Station. as easily as one can extract a file from a remote server today, using a file transfer protocol. In a second category, NASA spacecraft will make use of commercial satellite communication (SATCOM) systems. Some of those services will come from purchasing time on unused transponders that cover landmasses. While it is likely there will be gaps in service coverage, Internet services should be available using these systems. This report addresses alternative methods of implementing a full duplex enhancement of the GRC developed experimental Ka-Band Direct Data Distribution (D3) space-to-ground communication link. The resulting duplex version is called the Duplex Direct Data Distribution (D4) system. The D4 system is intended to provide high-data-rate commercial direct or internet-based communications service between the NASA spacecraft in low earth orbit (LEO) and the respective principal investigators associated with these spacecraft. Candidate commercial services were assessed regarding their near-term potential to meet NASA requirements. Candidates included Ka-band and V-band geostationary orbit and non-geostationary orbit satellite relay services and direct downlink ("LEO teleport") services. End-to-end systems concepts were examined and characterized in terms of alternative link layer architectures. Alternatives included a Direct Link, a Relay Link, a Hybrid Link, and a Dual Mode Link. The direct link assessment examined sample ground terminal placements and antenna angle issues. The SATCOM-based alternatives examined existing or proposed commercial

  5. CubeSat Cloud: A framework for distributed storage, processing and communication of remote sensing data on cubesat clusters

    NASA Astrophysics Data System (ADS)

    Challa, Obulapathi Nayudu

    CubeSat Cloud is a novel vision for a space based remote sensing network that includes a collection of small satellites (including CubeSats), ground stations, and a server, where a CubeSat is a miniaturized satellite with a volume of a 10x10x10 cm cube and has a weight of approximately 1 kg. The small form factor of CubeSats limits the processing and communication capabilities. Implemented and deployed CubeSats have demonstrated about 1 GHz processing speed and 9.6 kbps communication speed. A CubeSat in its current state can take hours to process a 100 MB image and more than a day to downlink the same, which prohibits remote sensing, considering the limitations in ground station access time for a CubeSat. This dissertation designs an architecture and supporting networking protocols to create CubeSat Cloud, a distributed processing, storage and communication framework that will enable faster execution of remote sensing missions on CubeSat clusters. The core components of CubeSat Cloud are CubeSat Distributed File System, CubeSat MapMerge, and CubeSat Torrent. The CubeSat Distributed File System has been created for distributing of large amounts of data among the satellites in the cluster. Once the data is distributed, CubeSat MapReduce has been created to process the data in parallel, thereby reducing the processing load for each CubeSat. Finally, CubeSat Torrent has been created to downlink the data at each CubeSat to a distributed set of ground stations, enabling faster asynchronous downloads. Ground stations send the downlinked data to the server to reconstruct the original image and store it for later retrieval. Analysis of the proposed CubeSat Cloud architecture was performed using a custom-designed simulator, called CubeNet and an emulation test bed using Raspberry Pi devices. Results show that for cluster sizes ranging from 5 to 25 small satellites, faster download speeds up to 4 to 22 times faster - can be achieved when using CubeSat Cloud, compared to a

  6. Coded 16-CPFSK for downlink applications

    NASA Technical Reports Server (NTRS)

    Davis, Robert

    1992-01-01

    A bandwidth-efficient constant-envelope Proof-of-Concept (POC) modem is described. The modem was developed on an Advanced Modulation Techniques Development contract for the NASA/Lewis Research Center. The POC modem employs 16-ary Continuous Phase Frequency Shift Keying (16-CPFSK) modulation. The 16 frequencies are spaced every 1/16th baud rate which produces a compact spectrum allowing 2 bits/sec/Hz operation. The modem is designed for 200 mb/s Time Division Multiple Access (TDMA) application with 100 MHz adjacent channel spacing. Overall rate 3.4 convolutional coding is incorporated. The demodulator differs significantly from typical quadrature phase detector approaches in that phase is coherently measured by processing the baseband output of a frequency discriminator. Baud rate phase samples for the baseband processor are subsequently decoded to yield the original data stream. The method of encoding onto the 16-ary symbol-ending phase nodes, together with convolutional coding gain, results in near Quadrature Phase Shift Keying (QPSK) theoretical performance. The modulated signal is of constant envelope; thus the power amplifier can be saturated for peak performance. The spectrum is inherently bandlimited and requires no RF filter for sidelobe containment. Two novel theoretical techniques are used in this 16-CPFSK modem: (1) coherent phase measurements are obtained by processing an FM discriminator baseband output; and (2) modulation is accomplished via a closed-loop-linearized voltage controlled oscillator (VCO).

  7. Deep Space Mission Emergency Mode Downlink

    NASA Technical Reports Server (NTRS)

    Kantak, Anil V.

    2008-01-01

    This paper investigates telecommunications between a deep space mission satellite and the ground station during an emergency mode. Once emergency is detected, spacecraft is put into a safe mode, i.e., antenna to be used for emergency mode communications is pointed towards the sun and use total available power to transmit. There are many parameters affecting communications in this mode and these should be properly balanced to produce desired results. This paper explores the effectiveness of spacecraft antenna gain pattern in the emergency mode with respect to positions of the spacecraft, earth, Sun Earth Probe (SEP) angle at the receiving antenna, and the range of the spacecraft with respect to the ground station. The paper also provides parabolic reflector antenna diameter that should be used for emergency mode as a function of the satellite to sun range in the solar system.

  8. Distribute What?

    ERIC Educational Resources Information Center

    Brown, Wayne A.

    1989-01-01

    Distributed Data Processing, linking a central processing unit to remote computer sites, allows end users more control over their own destiny. Schools have distributed hardware and software but not talent. The primary goal of these staff experts should be to educate users as fully as they can. (MLW)

  9. Distributed Intelligence.

    ERIC Educational Resources Information Center

    McLagan, Patricia A.

    2003-01-01

    Distributed intelligence occurs when people in an organization take responsibility for creating innovations, solving problems, and making decisions. Organizations that have it excel in their markets and the global environment. (Author/JOW)

  10. Distributed Leadership.

    ERIC Educational Resources Information Center

    Lashway, Larry

    2003-01-01

    School-reform efforts in recent years have stressed, and expanded, the leadership role of the principal. But in the view of many analysts, the task of transforming a school is too complex for one person to accomplish alone. Consequently, a new model of leadership is developing: distributed leadership. This Research Roundup summarizes five…

  11. Distributed Optimization

    NASA Technical Reports Server (NTRS)

    Macready, William; Wolpert, David

    2005-01-01

    We demonstrate a new framework for analyzing and controlling distributed systems, by solving constrained optimization problems with an algorithm based on that framework. The framework is ar. information-theoretic extension of conventional full-rationality game theory to allow bounded rational agents. The associated optimization algorithm is a game in which agents control the variables of the optimization problem. They do this by jointly minimizing a Lagrangian of (the probability distribution of) their joint state. The updating of the Lagrange parameters in that Lagrangian is a form of automated annealing, one that focuses the multi-agent system on the optimal pure strategy. We present computer experiments for the k-sat constraint satisfaction problem and for unconstrained minimization of NK functions.

  12. Distributed SLAM

    NASA Astrophysics Data System (ADS)

    Binns, Lewis A.; Valachis, Dimitris; Anderson, Sean; Gough, David W.; Nicholson, David; Greenway, Phil

    2002-07-01

    Previously, we have developed techniques for Simultaneous Localization and Map Building based on the augmented state Kalman filter. Here we report the results of experiments conducted over multiple vehicles each equipped with a laser range finder for sensing the external environment, and a laser tracking system to provide highly accurate ground truth. The goal is simultaneously to build a map of an unknown environment and to use that map to navigate a vehicle that otherwise would have no way of knowing its location, and to distribute this process over several vehicles. We have constructed an on-line, distributed implementation to demonstrate the principle. In this paper we describe the system architecture, the nature of the experimental set up, and the results obtained. These are compared with the estimated ground truth. We show that distributed SLAM has a clear advantage in the sense that it offers a potential super-linear speed-up over single vehicle SLAM. In particular, we explore the time taken to achieve a given quality of map, and consider the repeatability and accuracy of the method. Finally, we discuss some practical implementation issues.

  13. Distributed Saturation

    NASA Technical Reports Server (NTRS)

    Chung, Ming-Ying; Ciardo, Gianfranco; Siminiceanu, Radu I.

    2007-01-01

    The Saturation algorithm for symbolic state-space generation, has been a recent break-through in the exhaustive veri cation of complex systems, in particular globally-asyn- chronous/locally-synchronous systems. The algorithm uses a very compact Multiway Decision Diagram (MDD) encoding for states and the fastest symbolic exploration algo- rithm to date. The distributed version of Saturation uses the overall memory available on a network of workstations (NOW) to efficiently spread the memory load during the highly irregular exploration. A crucial factor in limiting the memory consumption during the symbolic state-space generation is the ability to perform garbage collection to free up the memory occupied by dead nodes. However, garbage collection over a NOW requires a nontrivial communication overhead. In addition, operation cache policies become critical while analyzing large-scale systems using the symbolic approach. In this technical report, we develop a garbage collection scheme and several operation cache policies to help on solving extremely complex systems. Experiments show that our schemes improve the performance of the original distributed implementation, SmArTNow, in terms of time and memory efficiency.

  14. A Personal, Distributed Exposimeter: Procedure for Design, Calibration, Validation, and Application

    PubMed Central

    Thielens, Arno; Vanveerdeghem, Peter; Van Torre, Patrick; Gängler, Stephanie; Röösli, Martin; Rogier, Hendrik; Martens, Luc; Joseph, Wout

    2016-01-01

    This paper describes, for the first time, the procedure for the full design, calibration, uncertainty analysis, and practical application of a personal, distributed exposimeter (PDE) for the detection of personal exposure in the Global System for Mobile Communications (GSM) downlink (DL) band around 900 MHz (GSM 900 DL). The PDE is a sensor that consists of several body-worn antennas. The on-body location of these antennas is investigated using numerical simulations and calibration measurements in an anechoic chamber. The calibration measurements and the simulations result in a design (or on-body setup) of the PDE. This is used for validation measurements and indoor radio frequency (RF) exposure measurements in Ghent, Belgium. The main achievements of this paper are: first, the demonstration, using both measurements and simulations, that a PDE consisting of multiple on-body textile antennas will have a lower measurement uncertainty for personal RF exposure than existing on-body sensors; second, a validation of the PDE, which proves that the device correctly estimates the incident power densities; and third, a demonstration of the usability of the PDE for real exposure assessment measurements. To this aim, the validated PDE is used for indoor measurements in a residential building in Ghent, Belgium, which yield an average incident power density of 0.018 mW/m². PMID:26840320

  15. Data Processing, Archiving and Distribution at the WISE Science Data Center

    NASA Astrophysics Data System (ADS)

    Cutri, Roc M.; Conrow, T.; Alles, R.; Brandenberg, H.; Evans, T.; Fowler, J.; Gelino, C.; Jarrett, T.; Kirkpatrick, J. D.; Marsh, K.; Masci, F.; McCallon, H.; Padgett, D.; Wheelock, S.; Yan, L.; Tholen, D.

    2009-01-01

    The Wide-Field Infrared Survey Explorer (WISE), scheduled for launch in November 2009, will conduct an imaging survey of the entire sky in the 3.3, 4.7, 12 and 23 micron bands. Each day during its six-month mission WISE will scan 4800 sq.deg. of the sky, and will downlink approximately 50GB of raw science imaging data and engineering telemetry. The Infrared Processing and Analysis Center is the WISE Science Data Center (WSDC) and is responsible for processing, archiving and distribution of WISE science data. We describe the five elements of the WISE Science Data (WSDS) that will carry out these functions: INGEST which receives and merges science and ancillary data from WISE Mission Operations Center and stages for processing; PIPELINES which performs image calibration, source extraction and calibration on both single-exposure and coadded WISE images; QA which performs automated science data quality assessment and scoring; ARCHIVE which provides storage of and access to raw and processed WISE data products and metadata; FPG which extracts the final WISE Image Atlas and Source Catalog from the "working databases" generated by the data processing system and prepares them for public release; and EXEC which manages job execution and compute and storage resources for the other WSDS elements.

  16. Product Distributions for Distributed Optimization. Chapter 1

    NASA Technical Reports Server (NTRS)

    Bieniawski, Stefan R.; Wolpert, David H.

    2004-01-01

    With connections to bounded rational game theory, information theory and statistical mechanics, Product Distribution (PD) theory provides a new framework for performing distributed optimization. Furthermore, PD theory extends and formalizes Collective Intelligence, thus connecting distributed optimization to distributed Reinforcement Learning (FU). This paper provides an overview of PD theory and details an algorithm for performing optimization derived from it. The approach is demonstrated on two unconstrained optimization problems, one with discrete variables and one with continuous variables. To highlight the connections between PD theory and distributed FU, the results are compared with those obtained using distributed reinforcement learning inspired optimization approaches. The inter-relationship of the techniques is discussed.

  17. K-band FET amplifier for satellite downlink

    NASA Technical Reports Server (NTRS)

    Goel, J.; Cheung, R. P.

    1984-01-01

    State-of-the-art performance is demonstrated with solid-state amplifiers in K-band. The amplifier provides 8.2 watts of power with 39 dB gain over a frequency band of 1.4 GHz. Nonlinearity analyses of solid-state amplifiers suggest that system performance can be improved significantly by using an FET amplifier. Preliminary investigations reveal that the solid-state amplifiers can be space-qualified and can be expected to replace the TWTA in many communication links in the near future. It is pointed out that with improvements in device technology, the power, bandwidth and efficiency of solid-state amplifiers using FETs can be further improved. With FETs operating at a junction temperature of less than 125 C, solid-state amplifiers are inherently reliable, indicating a ten-year mean time to failure.

  18. Telemetry downlink interfaces and level-zero processing

    NASA Technical Reports Server (NTRS)

    Horan, S.; Pfeiffer, J.; Taylor, J.

    1991-01-01

    The technical areas being investigated are as follows: (1) processing of space to ground data frames; (2) parallel architecture performance studies; and (3) parallel programming techniques. Additionally, the University administrative details and the technical liaison between New Mexico State University and Goddard Space Flight Center are addressed.

  19. Shuttle/TDRSS Ku-band downlink study

    NASA Technical Reports Server (NTRS)

    Meyer, R.

    1976-01-01

    Assessing the adequacy of the baseline signal design approach, developing performance specifications for the return link hardware, and performing detailed design and parameter optimization tasks was accomplished by completing five specific study tasks. The results of these tasks show that the basic signal structure design is sound and that the goals can be met. Constraints placed on return link hardware by this structure allow reasonable specifications to be written so that no extreme technical risk areas in equipment design are foreseen. A third channel can be added to the PM mode without seriously degrading the other services. The feasibility of using only a PM mode was shown to exist, however, this will require use of some digital TV transmission techniques. Each task and its results are summarized.

  20. Distributive Education. Physical Distribution. Instructor's Curriculum.

    ERIC Educational Resources Information Center

    Missouri Univ., Columbia. Instructional Materials Lab.

    This distributive education performance-based instructional unit is designed to help students understand the system of physical distribution and to act as an aid to guiding students in preparing for future careers in the transportation industry dealing with the retail, wholesale, and service occupations. (Physical distribution involves the moving…

  1. Feasibility Activities Completed for the Direct Data Distribution (D(sup )3) Experiment

    NASA Technical Reports Server (NTRS)

    Wald, Lawrence W.

    2000-01-01

    The Direct Data Distribution (D(sup 3)) project being designed at the NASA Glenn Research Center at Lewis Field will demonstrate a high-performance communications system that transmits information at up to 1.2 gigabits per second (Gbps) from an advanced technology payload carried by the space shuttles in low Earth orbit to small (0.9-m) autonomously tracking terminals on the Earth. The flight communications package features a solid-state, phased-array antenna operating in the commercial K-band frequency that electronically steers two independently controlled downlink beams toward low-cost tracking ground terminals. The array enables agile, vibration-free beam steering at reduced size and weight with increased reliability over traditional mechanically steered reflectors. The flight experiment will also demonstrate efficient digital modulation technology that allows transmission of substantially increased amounts of latency-tolerant data (up to 72 Gb of data per minute of contact time) with very high quality (10(exp -11) bit error rate). D(sup 3) enables transmission from low-Earth-orbit science spacecraft, the shuttles, or the International Space Station directly to NASA field centers and principle investigator sites, or directly into the commercial terrestrial telecommunications network for remote distribution and archive. The ground terminal features a cryocooled receiver for ultralow noise and a reduced antenna aperture as well as open-loop tracking for unattended operations. The D(sup 3) technology validation and service demonstration will help to facilitate NASA's transition from using Government-owned communications assets to using commercially provided services.

  2. Frequency-Rank Distributions

    ERIC Educational Resources Information Center

    Brookes, Bertram C.; Griffiths, Jose M.

    1978-01-01

    Frequency, rank, and frequency rank distributions are defined. Extensive discussion on several aspects of frequency rank distributions includes the Poisson process as a means of exploring the stability of ranks; the correlation of frequency rank distributions; and the transfer coefficient, a new measure in frequency rank distribution. (MBR)

  3. Annual Coal Distribution

    EIA Publications

    2016-01-01

    The Annual Coal Distribution Report (ACDR) provides detailed information on domestic coal distribution by origin state, destination state, consumer category, and method of transportation. Also provided is a summary of foreign coal distribution by coal-producing state. All data for the report year are final and this report supersedes all data in the quarterly distribution reports.

  4. STIS MAMA Fold Distribution

    NASA Astrophysics Data System (ADS)

    Wheeler, Thomas

    2012-10-01

    The performance of MAMA microchannel plates can be monitored using a MAMA fold distribution procedure. The fold distribution provides a measurement of the distribution of charge cloud sizes incident upon the anode giving some measure of change in the pulse-height distribution of the MCP and, therefore, MCP gain. This proposal executes the same steps as the STIS MAMA Fold Distribution, Proposal 12778, as Cycle 19.

  5. STIS MAMA Fold Distribution

    NASA Astrophysics Data System (ADS)

    Wheeler, Thomas

    2013-10-01

    The performance of MAMA microchannel plates can be monitored using a MAMA fold distribution procedure. The fold distribution provides a measurement of the distribution of charge cloud sizes incident upon the anode giving some measure of change in the pulse-height distribution of the MCP and, therefore, MCP gain. This proposal executes the same steps as the STIS MAMA Fold Distribution, Proposal 13149, as Cycle 20.

  6. Distributed Data Management and Distributed File Systems

    NASA Astrophysics Data System (ADS)

    Girone, Maria

    2015-12-01

    The LHC program has been successful in part due to the globally distributed computing resources used for collecting, serving, processing, and analyzing the large LHC datasets. The introduction of distributed computing early in the LHC program spawned the development of new technologies and techniques to synchronize information and data between physically separated computing centers. Two of the most challenges services are the distributed file systems and the distributed data management systems. In this paper I will discuss how we have evolved from local site services to more globally independent services in the areas of distributed file systems and data management and how these capabilities may continue to evolve into the future. I will address the design choices, the motivations, and the future evolution of the computing systems used for High Energy Physics.

  7. Exponentiated power Lindley distribution

    PubMed Central

    Ashour, Samir K.; Eltehiwy, Mahmoud A.

    2014-01-01

    A new generalization of the Lindley distribution is recently proposed by Ghitany et al. [1], called as the power Lindley distribution. Another generalization of the Lindley distribution was introduced by Nadarajah et al. [2], named as the generalized Lindley distribution. This paper proposes a more generalization of the Lindley distribution which generalizes the two. We refer to this new generalization as the exponentiated power Lindley distribution. The new distribution is important since it contains as special sub-models some widely well-known distributions in addition to the above two models, such as the Lindley distribution among many others. It also provides more flexibility to analyze complex real data sets. We study some statistical properties for the new distribution. We discuss maximum likelihood estimation of the distribution parameters. Least square estimation is used to evaluate the parameters. Three algorithms are proposed for generating random data from the proposed distribution. An application of the model to a real data set is analyzed using the new distribution, which shows that the exponentiated power Lindley distribution can be used quite effectively in analyzing real lifetime data. PMID:26644927

  8. Doubly Distributed Transactions

    2014-08-25

    Doubly Distributed Transactions (D2T) offers a technique for managing operations from a set of parallel clients with a collection of distributed services. It detects and manages faults. Example code with a test harness is also provided

  9. Distributed Learning Metadata Standards

    ERIC Educational Resources Information Center

    McClelland, Marilyn

    2004-01-01

    Significant economies can be achieved in distributed learning systems architected with a focus on interoperability and reuse. The key building blocks of an efficient distributed learning architecture are the use of standards and XML technologies. The goal of plug and play capability among various components of a distributed learning system…

  10. Probability distributions for magnetotellurics

    SciTech Connect

    Stodt, John A.

    1982-11-01

    Estimates of the magnetotelluric transfer functions can be viewed as ratios of two complex random variables. It is assumed that the numerator and denominator are governed approximately by a joint complex normal distribution. Under this assumption, probability distributions are obtained for the magnitude, squared magnitude, logarithm of the squared magnitude, and the phase of the estimates. Normal approximations to the distributions are obtained by calculating mean values and variances from error propagation, and the distributions are plotted with their normal approximations for different percentage errors in the numerator and denominator of the estimates, ranging from 10% to 75%. The distribution of the phase is approximated well by a normal distribution for the range of errors considered, while the distribution of the logarithm of the squared magnitude is approximated by a normal distribution for a much larger range of errors than is the distribution of the squared magnitude. The distribution of the squared magnitude is most sensitive to the presence of noise in the denominator of the estimate, in which case the true distribution deviates significantly from normal behavior as the percentage errors exceed 10%. In contrast, the normal approximation to the distribution of the logarithm of the magnitude is useful for errors as large as 75%.

  11. Analyzing mobile WiMAX base station deployment under different frequency planning strategies

    NASA Astrophysics Data System (ADS)

    Salman, M. K.; Ahmad, R. B.; Ali, Ziad G.; Aldhaibani, Jaafar A.; Fayadh, Rashid A.

    2015-05-01

    The frequency spectrum is a precious resource and scarce in the communication markets. Therefore, different techniques are adopted to utilize the available spectrum in deploying WiMAX base stations (BS) in cellular networks. In this paper several types of frequency planning techniques are illustrated, and a comprehensive comparative study between conventional frequency reuse of 1 (FR of 1) and fractional frequency reuse (FFR) is presented. These techniques are widely used in network deployment, because they employ universal frequency (using all the available bandwidth) in their base station installation/configuration within network system. This paper presents a network model of 19 base stations in order to be employed in the comparison of the aforesaid frequency planning techniques. Users are randomly distributed within base stations, users' resource mapping and their burst profile selection are based on the measured signal to interference plus-noise ratio (SINR). Simulation results reveal that the FFR has advantages over the conventional FR of 1 in various metrics. 98 % of downlink resources (slots) are exploited when FFR is applied, whilst it is 81 % at FR of 1. Data rate of FFR has been increased to 10.6 Mbps, while it is 7.98 Mbps at FR of 1. The spectral efficiency is better enhanced (1.072 bps/Hz) at FR of 1 than FFR (0.808 bps/Hz), since FR of 1 exploits all the Bandwidth. The subcarrier efficiency shows how many data bits that can be carried by subcarriers under different frequency planning techniques, the system can carry more data bits under FFR (2.40 bit/subcarrier) than FR of 1 (1.998 bit/subcarrier). This study confirms that FFR can perform better than conventional frequency planning (FR of 1) which made it a strong candidate for WiMAX BS deployment in cellular networks.

  12. FRIB cryogenic distribution system

    SciTech Connect

    Ganni, Venkatarao; Dixon, Kelly D.; Laverdure, Nathaniel A.; Knudsen, Peter N.; Arenius, Dana M.; Barrios, Matthew N.; Jones, S.; Johnson, M.; Casagrande, Fabio

    2014-01-01

    The Michigan State University Facility for Rare Isotope Beams (MSU-FRIB) helium distribution system has been revised to include bayonet/warm valve type disconnects between each cryomodule and the transfer line distribution system, similar to the Thomas Jefferson National Accelerator Facility (JLab) and the Spallation Neutron Source (SNS) cryogenic distribution systems. The heat loads at various temperature levels and some of the features in the design of the distribution system are outlined. The present status, the plans for fabrication, and the procurement approach for the helium distribution system are also included.

  13. FRIB cryogenic distribution system

    SciTech Connect

    Ganni, V.; Dixon, K.; Laverdure, N.; Knudsen, P.; Arenius, D.; Barrios, M.; Jones, S.; Johnson, M.; Casagrande, F.

    2014-01-29

    The Michigan State University Facility for Rare Isotope Beams (MSU-FRIB) helium distribution system has been revised to include bayonet/warm valve type disconnects between each cryomodule and the transfer line distribution system, similar to the Thomas Jefferson National Accelerator Facility (JLab) and the Spallation Neutron Source (SNS) cryogenic distribution systems. The heat loads at various temperature levels and some of the features in the design of the distribution system are outlined. The present status, the plans for fabrication, and the procurement approach for the helium distribution system are also included.

  14. Verification of LHS distributions.

    SciTech Connect

    Swiler, Laura Painton

    2006-04-01

    This document provides verification test results for normal, lognormal, and uniform distributions that are used in Sandia's Latin Hypercube Sampling (LHS) software. The purpose of this testing is to verify that the sample values being generated in LHS are distributed according to the desired distribution types. The testing of distribution correctness is done by examining summary statistics, graphical comparisons using quantile-quantile plots, and format statistical tests such as the Chisquare test, the Kolmogorov-Smirnov test, and the Anderson-Darling test. The overall results from the testing indicate that the generation of normal, lognormal, and uniform distributions in LHS is acceptable.

  15. Bivariate extreme value distributions

    NASA Technical Reports Server (NTRS)

    Elshamy, M.

    1992-01-01

    In certain engineering applications, such as those occurring in the analyses of ascent structural loads for the Space Transportation System (STS), some of the load variables have a lower bound of zero. Thus, the need for practical models of bivariate extreme value probability distribution functions with lower limits was identified. We discuss the Gumbel models and present practical forms of bivariate extreme probability distributions of Weibull and Frechet types with two parameters. Bivariate extreme value probability distribution functions can be expressed in terms of the marginal extremel distributions and a 'dependence' function subject to certain analytical conditions. Properties of such bivariate extreme distributions, sums and differences of paired extremals, as well as the corresponding forms of conditional distributions, are discussed. Practical estimation techniques are also given.

  16. Distributed generation systems model

    SciTech Connect

    Barklund, C.R.

    1994-12-31

    A slide presentation is given on a distributed generation systems model developed at the Idaho National Engineering Laboratory, and its application to a situation within the Idaho Power Company`s service territory. The objectives of the work were to develop a screening model for distributed generation alternatives, to develop a better understanding of distributed generation as a utility resource, and to further INEL`s understanding of utility concerns in implementing technological change.

  17. Cooling water distribution system

    DOEpatents

    Orr, Richard

    1994-01-01

    A passive containment cooling system for a nuclear reactor containment vessel. Disclosed is a cooling water distribution system for introducing cooling water by gravity uniformly over the outer surface of a steel containment vessel using an interconnected series of radial guide elements, a plurality of circumferential collector elements and collector boxes to collect and feed the cooling water into distribution channels extending along the curved surface of the steel containment vessel. The cooling water is uniformly distributed over the curved surface by a plurality of weirs in the distribution channels.

  18. Statistical distribution sampling

    NASA Technical Reports Server (NTRS)

    Johnson, E. S.

    1975-01-01

    Determining the distribution of statistics by sampling was investigated. Characteristic functions, the quadratic regression problem, and the differential equations for the characteristic functions are analyzed.

  19. Testing Nested Distributions

    NASA Astrophysics Data System (ADS)

    Economou, P.

    2010-09-01

    A number of criteria, test statistics and diagnostic plots have been developed in order to test the adapted distribution assumption. Usually, a simpler distribution is tested against a more complicated one (by adding an extra parameter), which include the first distribution as a special case (nested distributions). A characteristic example of such cases is the Burr XII distribution which can be obtained under the proportional hazards frailty model by assuming a Weibull baseline function and a Gamma frailty distribution with mean frailty equal to 1 and variance equal to θ. In this work, two new easy to construct and to interpret tests, a diagnostic plot and an asymptotic test, are presented in order to test nested distributions. The asymptotic test is based on the approximation of the difference of the two estimated nested distribution functions using the first two terms of the Taylor's expansion while the diagnostic plot is constructed using the exact difference of the two fitted distribution functions. Simulation results, using data sets with and without censored observations, demonstrate that the proposed tests perform, in most of the cases, better than other test statistics such as the LR and the Wald.

  20. Smart distribution systems

    DOE PAGES

    Jiang, Yazhou; Liu, Chen -Ching; Xu, Yin

    2016-04-19

    The increasing importance of system reliability and resilience is changing the way distribution systems are planned and operated. To achieve a distribution system self-healing against power outages, emerging technologies and devices, such as remote-controlled switches (RCSs) and smart meters, are being deployed. The higher level of automation is transforming traditional distribution systems into the smart distribution systems (SDSs) of the future. The availability of data and remote control capability in SDSs provides distribution operators with an opportunity to optimize system operation and control. In this paper, the development of SDSs and resulting benefits of enhanced system capabilities are discussed. Amore » comprehensive survey is conducted on the state-of-the-art applications of RCSs and smart meters in SDSs. Specifically, a new method, called Temporal Causal Diagram (TCD), is used to incorporate outage notifications from smart meters for enhanced outage management. To fully utilize the fast operation of RCSs, the spanning tree search algorithm is used to develop service restoration strategies. Optimal placement of RCSs and the resulting enhancement of system reliability are discussed. Distribution system resilience with respect to extreme events is presented. Furthermore, test cases are used to demonstrate the benefit of SDSs. Active management of distributed generators (DGs) is introduced. Future research in a smart distribution environment is proposed.« less

  1. Software distribution using xnetlib

    SciTech Connect

    Dongarra, J.J. |; Rowan, T.H.; Wade, R.C.

    1993-06-01

    Xnetlib is a new tool for software distribution. Whereas its predecessor netlib uses e-mail as the user interface to its large collection of public-domain mathematical software, xnetlib uses an X Window interface and socket-based communication. Xnetlib makes it easy to search through a large distributed collection of software and to retrieve requested software in seconds.

  2. Advanced Distribution Management System

    NASA Astrophysics Data System (ADS)

    Avazov, Artur R.; Sobinova, Liubov A.

    2016-02-01

    This article describes the advisability of using advanced distribution management systems in the electricity distribution networks area and considers premises of implementing ADMS within the Smart Grid era. Also, it gives the big picture of ADMS and discusses the ADMS advantages and functionalities.

  3. Univariate Probability Distributions

    ERIC Educational Resources Information Center

    Leemis, Lawrence M.; Luckett, Daniel J.; Powell, Austin G.; Vermeer, Peter E.

    2012-01-01

    We describe a web-based interactive graphic that can be used as a resource in introductory classes in mathematical statistics. This interactive graphic presents 76 common univariate distributions and gives details on (a) various features of the distribution such as the functional form of the probability density function and cumulative distribution…

  4. Distribution and Marketing Syllabus.

    ERIC Educational Resources Information Center

    New York State Education Dept., Albany. Bureau of Secondary Curriculum Development.

    The distributive education program for grades 7 to 12 is organized around three career education phases: the career education phase (grades 7-10), the distributive phase (grade 11), and the competency cluster phase (grade 12). The grade 11 syllabus provides a six-page introduction which covers scheduling, cooperative work experience, the school…

  5. Wigner distributions for qudits

    SciTech Connect

    Chaturvedi, S.

    2006-11-15

    Two new approaches to the problem of setting up Wigner distributions for finite level quantum systems are proposed. Both arise by looking at the structure of the familiar Wigner distribution for Cartesian quantum mechanics from different perspectives. The two approaches have one common feature--each involves a 'square root' operation though of very different kinds.

  6. Groundwater and Distribution Workbook.

    ERIC Educational Resources Information Center

    Ekman, John E.

    Presented is a student manual designed for the Wisconsin Vocational, Technical and Adult Education Groundwater and Distribution Training Course. This program introduces waterworks operators-in-training to basic skills and knowledge required for the operation of a groundwater distribution waterworks facility. Arranged according to the general order…

  7. Distributed sensor networks

    NASA Astrophysics Data System (ADS)

    Lacoss, Richard T.

    1986-09-01

    The Distributed Sensor Networks (DSN) program was aimed at developing distributed target surveillance and tracking methods for systems employing multiple spatially distributed sensors and processing resources. Such systems would be made up of sensors, data bases, and processors distributed throughout an area and interconnected by an appropriate digital data communication system. The hypothesis of the program was that through netting and distributed processing, the information from many sensors could be combined to yield effective surveillance systems. The overall concept called for a mix of sensor types as well as geographically distributed sensors. Surveillance and tracking of low-flying aircraft with ground-based acoustic and imaging sensors was used to develop and evaluate DSN concepts in the light of a specific problem. An experimental DSN testbed system was developed and has been used to test and demonstrate DSN techniques. Small arrays of microphones providing directional information were employed as acoustic sensors and visible TV cameras were used as imaging sensors in the testbed system. The primary accomplishment during this final report period was the demonstration of distributed real time tracking using both TV and acoustic sensors. Tracking was implemented as a geographically decentralized confederacy of autonomous cooperating nodes. Thus the feasibility of this organization has been established for a DSN system containing multiple sensor types as well as distributed nodes.

  8. DSIM: A distributed simulator

    NASA Technical Reports Server (NTRS)

    Goswami, Kumar K.; Iyer, Ravishankar K.

    1990-01-01

    Discrete event-driven simulation makes it possible to model a computer system in detail. However, such simulation models can require a significant time to execute. This is especially true when modeling large parallel or distributed systems containing many processors and a complex communication network. One solution is to distribute the simulation over several processors. If enough parallelism is achieved, large simulation models can be efficiently executed. This study proposes a distributed simulator called DSIM which can run on various architectures. A simulated test environment is used to verify and characterize the performance of DSIM. The results of the experiments indicate that speedup is application-dependent and, in DSIM's case, is also dependent on how the simulation model is distributed among the processors. Furthermore, the experiments reveal that the communication overhead of ethernet-based distributed systems makes it difficult to achieve reasonable speedup unless the simulation model is computation bound.

  9. Plasma Sheet Energy Distributions

    NASA Astrophysics Data System (ADS)

    Sotirelis, T.; Lee, A. R.; Newell, P. T.

    2009-12-01

    Energy spectra of electrons and ions, as observed by DMSP, are fit to various distributions. The goal is to characterize the inner edge of the plasma sheet, so the focus is on large scale plasma sheet properties. Lower energy electron populations are ignored as they appear to be small-scale transients. Maxwellian, kappa and power-law distributed spectra are considered. Non-thermal ion distributions appear with greater frequency than anticipated. In order to be thermally distributed the differential energy flux must rise with a slope of ~2 toward a peak, after which the flux should fall sharply. The figure shows an apparently non-thermal ion distribution, together with a Maxwellian fit. The results from fits for one full year are presented.

  10. Distributed Propulsion Vehicles

    NASA Technical Reports Server (NTRS)

    Kim, Hyun Dae

    2010-01-01

    Since the introduction of large jet-powered transport aircraft, the majority of these vehicles have been designed by placing thrust-generating engines either under the wings or on the fuselage to minimize aerodynamic interactions on the vehicle operation. However, advances in computational and experimental tools along with new technologies in materials, structures, and aircraft controls, etc. are enabling a high degree of integration of the airframe and propulsion system in aircraft design. The National Aeronautics and Space Administration (NASA) has been investigating a number of revolutionary distributed propulsion vehicle concepts to increase aircraft performance. The concept of distributed propulsion is to fully integrate a propulsion system within an airframe such that the aircraft takes full synergistic benefits of coupling of airframe aerodynamics and the propulsion thrust stream by distributing thrust using many propulsors on the airframe. Some of the concepts are based on the use of distributed jet flaps, distributed small multiple engines, gas-driven multi-fans, mechanically driven multifans, cross-flow fans, and electric fans driven by turboelectric generators. This paper describes some early concepts of the distributed propulsion vehicles and the current turboelectric distributed propulsion (TeDP) vehicle concepts being studied under the NASA s Subsonic Fixed Wing (SFW) Project to drastically reduce aircraft-related fuel burn, emissions, and noise by the year 2030 to 2035.

  11. Long distance entanglement distribution

    NASA Astrophysics Data System (ADS)

    Broadfoot, Stuart Graham

    Developments in the interdisciplinary field of quantum information open up previously impossible abilities in the realms of information processing and communication. Quantum entanglement has emerged as one property of quantum systems that acts as a resource for quantum information processing and, in particular, enables teleportation and secure cryptography. Therefore, the creation of entangled resources is of key importance for the application of these technologies. Despite a great deal of research the efficient creation of entanglement over long distances is limited by inevitable noise. This problem can be overcome by creating entanglement between nodes in a network and then performing operations to distribute the entanglement over a long distance. This thesis contributes to the field of entanglement distribution within such quantum networks. Entanglement distribution has been extensively studied for one-dimensional networks resulting in "quantum repeater" protocols. However, little work has been done on higher dimensional networks. In these networks a fundamentally different scaling, called "long distance entanglement distribution", can appear between the resources and the distance separating the systems to be entangled. I reveal protocols that enable long distance entanglement distribution for quantum networks composed of mixed state and give a few limitations to the capabilities of entanglement distribution. To aid in the implementation of all entanglement distribution protocols I finish by introducing a new system, composed of an optical nanofibre coupled to a carbon nanotube, that may enable new forms of photo-detectors and quantum memories.

  12. Distributional Learning of Appearance

    PubMed Central

    Griffin, Lewis D.; Wahab, M. Husni; Newell, Andrew J.

    2013-01-01

    Opportunities for associationist learning of word meaning, where a word is heard or read contemperaneously with information being available on its meaning, are considered too infrequent to account for the rate of language acquisition in children. It has been suggested that additional learning could occur in a distributional mode, where information is gleaned from the distributional statistics (word co-occurrence etc.) of natural language. Such statistics are relevant to meaning because of the Distributional Principle that ‘words of similar meaning tend to occur in similar contexts’. Computational systems, such as Latent Semantic Analysis, have substantiated the viability of distributional learning of word meaning, by showing that semantic similarities between words can be accurately estimated from analysis of the distributional statistics of a natural language corpus. We consider whether appearance similarities can also be learnt in a distributional mode. As grounds for such a mode we advance the Appearance Hypothesis that ‘words with referents of similar appearance tend to occur in similar contexts’. We assess the viability of such learning by looking at the performance of a computer system that interpolates, on the basis of distributional and appearance similarity, from words that it has been explicitly taught the appearance of, in order to identify and name objects that it has not been taught about. Our experiment tests with a set of 660 simple concrete noun words. Appearance information on words is modelled using sets of images of examples of the word. Distributional similarity is computed from a standard natural language corpus. Our computation results support the viability of distributional learning of appearance. PMID:23460927

  13. Beam distributions beyond RMS

    SciTech Connect

    Decker, F.

    1995-05-05

    The beam is often represented only by its position (mean) and the width (rms=root mean squared) of its distribution. To achieve these beam parameters in a noisy condition with high backgrounds, a Gaussian distribution with offset (4 parameters) is fitted to the measured beam distribution. This gives a very robust answer and is not very sensitive to background subtraction techniques. To get higher moments of the distribution, like skew or kurtosis, a fitting function with one or two more parameters is desired which would model the higher moments. In this paper we will concentrate on an Asymmetric Gaussian and a Super Gaussian function that will give something like the skew and the kurtosis of the distribution. This information is used to quantify special beam distribution. Some are unwanted like beam tails (skew) from transverse wakefields, higher order dispersive aberrations or potential well distortion in a damping ring. A negative kurtosis of a beam distribution describes a more rectangular, compact shape like with an over-compressed beam in {ital z} or a closed to double-horned energy distribution, while a positive kurtosis looks more like a ``Christmas tree`` and can quantify a beam mismatch after filamentation. Besides the advantages of the quantification, there are some distributions which need a further investigation like long flat tails which create background particles in a detector. In particle simulations on the other hand a simple rms number might grossly overestimate the effective size (e.g. for producing luminosity) due to a few particles which are far away from the core. This can reduce the practical gain of a big theoretical improvement in the beam size. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  14. Beam distributions beyond RMS

    SciTech Connect

    Decker, F.J.

    1994-09-01

    The beam is often represented only by its position (mean) and the width (rms = root mean squared) of its distribution. To achieve these beam parameters in a noisy condition with high backgrounds, a Gaussian distribution with offset (4 parmeters) is fitted to the measured beam distribution. This gives a very robust answer and is not very sensitive to background subtraction techniques. To get higher moments of the distribution, like skew or kurtosis, a fitting function with one or two more parameters is desired which would model the higher moments. In this paper we will concentrate on an Asymmetric Gaussian and a Super Gaussian function that will give something like the skew and the kurtosis of the distribution. This information is used to quantify special beam distribution. Some are unwanted like beam tails (skew) from transverse wakefields, higher order dispersive aberrations or potential well distortion in a damping ring. A negative kurtosis of a beam distribution describes a more rectangular, compact shape like with an over-compressed beam in z or a closed to double-homed energy distribution, while a positive kurtosis looks more like a ``Christmas tree`` and can quantify a beam mismatch after filamentation. Besides the advantages of the quantification, there are some distributions which need a further investigation like long flat tails which create background particles in a detector. In particle simulations on the other hand a simple rms number might grossly overestimate the effective size (e.g. for producing luminosity) due to a few particles which are far away from the core. This can reduce the practical gain of a big theoretical improvement in the beam size.

  15. Technologies for distributed defense

    NASA Astrophysics Data System (ADS)

    Seiders, Barbara; Rybka, Anthony

    2002-07-01

    For Americans, the nature of warfare changed on September 11, 2001. Our national security henceforth will require distributed defense. One extreme of distributed defense is represented by fully deployed military troops responding to a threat from a hostile nation state. At the other extreme is a country of 'citizen soldiers', with families and communities securing their common defense through heightened awareness, engagement as good neighbors, and local support of and cooperation with local law enforcement, emergency and health care providers. Technologies - for information exploitation, biological agent detection, health care surveillance, and security - will be critical to ensuring success in distributed defense.

  16. Technologies for Distributed Defense

    SciTech Connect

    Seiders, Barbara AB; Rybka, Anthony J.

    2002-07-01

    For Americans, the nature of warfare changed on September 11, 2001. Our national security henceforth will require distributed defense. One extreme of distributed defense is represented by fully deployed military troops responding to a threat from a hostile nation state. At the other extreme is a country of "citizen soldiers," with families and communities securing their common defense through heightened awareness, engagement as good neighbors, and local support of and cooperation with local law enforcement, emergency and health care providers. Technologies - for information exploitation, biological agent detection, health care surveillance, and security - will be critical to ensuring success in distributed defense.

  17. Financing Distributed Generation

    SciTech Connect

    Walker, A.

    2001-06-29

    This paper introduces the engineer who is undertaking distributed generation projects to a wide range of financing options. Distributed generation systems (such as internal combustion engines, small gas turbines, fuel cells and photovoltaics) all require an initial investment, which is recovered over time through revenues or savings. An understanding of the cost of capital and financing structures helps the engineer develop realistic expectations and not be offended by the common requirements of financing organizations. This paper discusses several mechanisms for financing distributed generation projects: appropriations; debt (commercial bank loan); mortgage; home equity loan; limited partnership; vendor financing; general obligation bond; revenue bond; lease; Energy Savings Performance Contract; utility programs; chauffage (end-use purchase); and grants. The paper also discusses financial strategies for businesses focusing on distributed generation: venture capital; informal investors (''business angels''); bank and debt financing; and the stock market.

  18. Ticks: Geographic Distribution

    MedlinePlus

    ... Atlas. Download this map [PDF - 1 page] Lone star tick ( Amblyomma americanum ) Where found: Widely distributed in ... is distinguished by a white dot or “lone star” on her back. Lone star tick saliva can ...

  19. Estimating Bias Error Distributions

    NASA Technical Reports Server (NTRS)

    Liu, Tian-Shu; Finley, Tom D.

    2001-01-01

    This paper formulates the general methodology for estimating the bias error distribution of a device in a measuring domain from less accurate measurements when a minimal number of standard values (typically two values) are available. A new perspective is that the bias error distribution can be found as a solution of an intrinsic functional equation in a domain. Based on this theory, the scaling- and translation-based methods for determining the bias error distribution arc developed. These methods are virtually applicable to any device as long as the bias error distribution of the device can be sufficiently described by a power series (a polynomial) or a Fourier series in a domain. These methods have been validated through computational simulations and laboratory calibration experiments for a number of different devices.

  20. DOLIB: Distributed Object Library

    SciTech Connect

    D`Azevedo, E.F.; Romine, C.H.

    1994-10-01

    This report describes the use and implementation of DOLIB (Distributed Object Library), a library of routines that emulates global or virtual shared memory on Intel multiprocessor systems. Access to a distributed global array is through explicit calls to gather and scatter. Advantages of using DOLIB include: dynamic allocation and freeing of huge (gigabyte) distributed arrays, both C and FORTRAN callable interfaces, and the ability to mix shared-memory and message-passing programming models for ease of use and optimal performance. DOLIB is independent of language and compiler extensions and requires no special operating system support. DOLIB also supports automatic caching of read-only data for high performance. The virtual shared memory support provided in DOLIB is well suited for implementing Lagrangian particle tracking techniques. We have also used DOLIB to create DONIO (Distributed Object Network I/O Library), which obtains over a 10-fold improvement in disk I/O performance on the Intel Paragon.

  1. Parton Distributions Working Group

    SciTech Connect

    de Barbaro, L.; Keller, S. A.; Kuhlmann, S.; Schellman, H.; Tung, W.-K.

    2000-07-20

    This report summarizes the activities of the Parton Distributions Working Group of the QCD and Weak Boson Physics workshop held in preparation for Run II at the Fermilab Tevatron. The main focus of this working group was to investigate the different issues associated with the development of quantitative tools to estimate parton distribution functions uncertainties. In the conclusion, the authors introduce a Manifesto that describes an optimal method for reporting data.

  2. Polygamy of distributed entanglement

    NASA Astrophysics Data System (ADS)

    Buscemi, Francesco; Gour, Gilad; Kim, Jeong San

    2009-07-01

    While quantum entanglement is known to be monogamous (i.e., shared entanglement is restricted in multipartite settings), here we show that distributed entanglement (or the potential for entanglement) is by nature polygamous. By establishing the concept of one-way unlocalizable entanglement (UE) and investigating its properties, we provide a polygamy inequality of distributed entanglement in tripartite quantum systems of arbitrary dimension. We also provide a polygamy inequality in multiqubit systems and several trade-offs between UE and other correlation measures.

  3. Sparse distributed memory

    NASA Technical Reports Server (NTRS)

    Kanerva, Pentti

    1988-01-01

    Theoretical models of the human brain and proposed neural-network computers are developed analytically. Chapters are devoted to the mathematical foundations, background material from computer science, the theory of idealized neurons, neurons as address decoders, and the search of memory for the best match. Consideration is given to sparse memory, distributed storage, the storage and retrieval of sequences, the construction of distributed memory, and the organization of an autonomous learning system.

  4. Distribution system simulator

    NASA Technical Reports Server (NTRS)

    Bahrami, K. A.; Kirkham, H.; Rahman, S.

    1986-01-01

    In a series of tests performed under the Department of Energy auspices, power line carrier propagation was observed to be anomalous under certain circumstances. To investigate the cause, a distribution system simulator was constructed. The simulator was a physical simulator that accurately represented the distribution system from below power frequency to above 50 kHz. Effects such as phase-to-phase coupling and skin effect were modeled. Construction details of the simulator, and experimental results from its use are presented.

  5. Sparse distributed memory

    SciTech Connect

    Kanerva, P.

    1988-01-01

    Theoretical models of the human brain and proposed neural-network computers are developed analytically. Chapters are devoted to the mathematical foundations, background material from computer science, the theory of idealized neurons, neurons as address decoders, and the search of memory for the best match. Consideration is given to sparse memory, distributed storage, the storage and retrieval of sequences, the construction of distributed memory, and the organization of an autonomous learning system. 63 refs.

  6. Polygamy of distributed entanglement

    SciTech Connect

    Buscemi, Francesco; Gour, Gilad; Kim, Jeong San

    2009-07-15

    While quantum entanglement is known to be monogamous (i.e., shared entanglement is restricted in multipartite settings), here we show that distributed entanglement (or the potential for entanglement) is by nature polygamous. By establishing the concept of one-way unlocalizable entanglement (UE) and investigating its properties, we provide a polygamy inequality of distributed entanglement in tripartite quantum systems of arbitrary dimension. We also provide a polygamy inequality in multiqubit systems and several trade-offs between UE and other correlation measures.

  7. NUV MAMA Fold Distribution

    NASA Astrophysics Data System (ADS)

    Wheeler, Thomas

    2009-07-01

    The performance of MAMA microchannel plate can be monitored using a MAMA fold analysis procedure. The fold analysis provides a measurement of the distribution of charge cloud sizes incident upon the anode giving some measure of changes in the pulse-height distribution of the MCP and, therefore, MCP gain. This proposal executes the same steps as the COS SMOV as proposal 13555 {visit 5}.

  8. STIS MAMA Fold Distribution

    NASA Astrophysics Data System (ADS)

    Wheeler, Thomas

    2010-09-01

    The performance of MAMA microchannel plates can be monitored using a MAMA fold analysis procedure. The fold analysis provides a measurement of the distribution of charge cloud sizes incident upon the anode giving some measure of changes in the pulse-height distribution of the MCP and, therefore, MCP gain. This proposal executes the same steps as the STIS MAMA Fold Analysis {11863} during Cycle 17.

  9. STIS MAMA Fold Distribution

    NASA Astrophysics Data System (ADS)

    Wheeler, Thomas

    2009-07-01

    The performance of MAMA microchannel plates can be monitored using a MAMA fold analysis procedure. The fold analysis provides a measurement of the distribution of charge cloud sizes incident upon the anode giving some measure of changes in the pulse-height distribution of the MCP and, therefore, MCP gain. This proposal executes the same steps as the STIS MAMA Fold Analysis {10035} during Cycle 12.

  10. STIS MAMA Fold Distribution

    NASA Astrophysics Data System (ADS)

    Wheeler, Thomas

    2011-10-01

    The performance of MAMA microchannel plates can be monitored using a MAMA fold analysis procedure. The fold analysis provides a measurement of the distribution of charge cloud sizes incident upon the anode giving some measure of changes in the pulse-height distribution of the MCP and, therefore, MCP gain. This proposal executes the same steps as the STIS MAMA Fold Analysis, Proposal 12416, as Cycle 18.

  11. Measuring personal exposure from 900MHz mobile phone base stations in Australia and Belgium using a novel personal distributed exposimeter.

    PubMed

    Bhatt, Chhavi Raj; Thielens, Arno; Redmayne, Mary; Abramson, Michael J; Billah, Baki; Sim, Malcolm R; Vermeulen, Roel; Martens, Luc; Joseph, Wout; Benke, Geza

    2016-01-01

    The aims of this study were to: i) measure personal exposure in the Global System for Mobile communications (GSM) 900MHz downlink (DL) frequency band with two systems of exposimeters, a personal distributed exposimeter (PDE) and a pair of ExpoM-RFs, ii) compare the GSM 900MHz DL exposures across various microenvironments in Australia and Belgium, and iii) evaluate the correlation between the PDE and ExpoM-RFs measurements. Personal exposure data were collected using the PDE and two ExpoM-RFs simultaneously across 34 microenvironments (17 each in Australia and Belgium) located in urban, suburban and rural areas. Summary statistics of the electric field strengths (V/m) were computed and compared across similar microenvironments in Australia and Belgium. The personal exposures across urban microenvironments were higher than those in the rural or suburban microenvironments. Likewise, the exposure levels across the outdoor were higher than those for indoor microenvironments. The five highest median exposure levels were: city centre (0.248V/m), bus (0.124V/m), railway station (0.105V/m), mountain/forest (rural) (0.057V/m), and train (0.055V/m) [Australia]; and bicycle (urban) (0.238V/m), tram station (0.238V/m), city centre (0.156V/m), residential outdoor (urban) (0.139V/m) and park (0.124V/m) [Belgium]. Exposures in the GSM900 MHz frequency band across most of the microenvironments in Australia were significantly lower than the exposures across the microenvironments in Belgium. Overall correlations between the PDE and the ExpoM-RFs measurements were high. The measured exposure levels were far below the general public reference levels recommended in the guidelines of the ICNIRP and the ARPANSA.

  12. The isotopic distribution conundrum.

    PubMed

    Valkenborg, Dirk; Mertens, Inge; Lemière, Filip; Witters, Erwin; Burzykowski, Tomasz

    2012-01-01

    Although access to high-resolution mass spectrometry (MS), especially in the field of biomolecular MS, is becoming readily available due to recent advances in MS technology, the accompanied information on isotopic distribution in high-resolution spectra is not used at its full potential, mainly because of lack of knowledge and/or awareness. In this review, we give an insight into the practical problems related to calculating the isotopic distribution for large biomolecules, and present an overview of methods for the calculation of the isotopic distribution. We discuss the key events that triggered the development of various algorithms and explain the rationale of how and why the various isotopic-distribution calculations were performed. The review is focused around the developmental stages as briefly outlined below, starting with the first observation of an isotopic distribution. The observations of Beynon in the field of organic MS that chlorine appeared in a mass spectrum as two variants with odds 3:1 lie at the basis of the first wave of algorithms for the calculation of the isotopic distribution, based on the atomic composition of a molecule. From here on, we explain why more complex biomolecules such as peptides exhibit a highly complex isotope pattern when assayed by MS, and we discuss how combinatorial difficulties complicate the calculation of the isotopic distribution on computers. For this purpose, we highlight three methods, which were introduced in the 1980s. These are the stepwise procedure introduced by Kubinyi, the polynomial expansion from Brownawell and Fillippo, and the multinomial expansion from Yergey. The next development was instigated by Rockwood, who suggested to decompose the isotopic distribution in terms of their nucleon count instead of the exact mass. In this respect, we could claim that the term "aggregated" isotopic distribution is more appropriate. Due to the simplification of the isotopic distribution to its aggregated counterpart

  13. Distributed replica dynamics

    NASA Astrophysics Data System (ADS)

    Zhang, Liang; Chill, Samuel T.; Henkelman, Graeme

    2015-11-01

    A distributed replica dynamics (DRD) method is proposed to calculate rare-event molecular dynamics using distributed computational resources. Similar to Voter's parallel replica dynamics (PRD) method, the dynamics of independent replicas of the system are calculated on different computational clients. In DRD, each replica runs molecular dynamics from an initial state for a fixed simulation time and then reports information about the trajectory back to the server. A simulation clock on the server accumulates the simulation time of each replica until one reports a transition to a new state. Subsequent calculations are initiated from within this new state and the process is repeated to follow the state-to-state evolution of the system. DRD is designed to work with asynchronous and distributed computing resources in which the clients may not be able to communicate with each other. Additionally, clients can be added or removed from the simulation at any point in the calculation. Even with heterogeneous computing clients, we prove that the DRD method reproduces the correct probability distribution of escape times. We also show this correspondence numerically; molecular dynamics simulations of Al(100) adatom diffusion using PRD and DRD give consistent exponential distributions of escape times. Finally, we discuss guidelines for choosing the optimal number of replicas and replica trajectory length for the DRD method.

  14. Sparse distributed memory overview

    NASA Technical Reports Server (NTRS)

    Raugh, Mike

    1990-01-01

    The Sparse Distributed Memory (SDM) project is investigating the theory and applications of massively parallel computing architecture, called sparse distributed memory, that will support the storage and retrieval of sensory and motor patterns characteristic of autonomous systems. The immediate objectives of the project are centered in studies of the memory itself and in the use of the memory to solve problems in speech, vision, and robotics. Investigation of methods for encoding sensory data is an important part of the research. Examples of NASA missions that may benefit from this work are Space Station, planetary rovers, and solar exploration. Sparse distributed memory offers promising technology for systems that must learn through experience and be capable of adapting to new circumstances, and for operating any large complex system requiring automatic monitoring and control. Sparse distributed memory is a massively parallel architecture motivated by efforts to understand how the human brain works. Sparse distributed memory is an associative memory, able to retrieve information from cues that only partially match patterns stored in the memory. It is able to store long temporal sequences derived from the behavior of a complex system, such as progressive records of the system's sensory data and correlated records of the system's motor controls.

  15. Distributed Wind Market Applications

    SciTech Connect

    Forsyth, T.; Baring-Gould, I.

    2007-11-01

    Distributed wind energy systems provide clean, renewable power for on-site use and help relieve pressure on the power grid while providing jobs and contributing to energy security for homes, farms, schools, factories, private and public facilities, distribution utilities, and remote locations. America pioneered small wind technology in the 1920s, and it is the only renewable energy industry segment that the United States still dominates in technology, manufacturing, and world market share. The series of analyses covered by this report were conducted to assess some of the most likely ways that advanced wind turbines could be utilized apart from large, central station power systems. Each chapter represents a final report on specific market segments written by leading experts in this field. As such, this document does not speak with one voice but rather a compendium of different perspectives, which are documented from a variety of people in the U.S. distributed wind field.

  16. Partonic Transverse Momentum Distributions

    SciTech Connect

    Rossi, Patrizia

    2010-08-04

    In recent years parton distributions have been generalized to account also for transverse degrees of freedom and new sets of more general distributions, Transverse Momentum Dependent (TMD) parton distributions and fragmentation functions were introduced. Different experiments worldwide (HERMES, COMPASS, CLAS, JLab-Hall A) have measurements of TMDs in semi-inclusive DIS processes as one of their main focuses of research. TMD studies are also an important part of the present and future Drell-Yan experiments at RICH and JPARC and GSI, respectively, Studies of TMDs are also one of the main driving forces of the Jefferson Lab (JLab) 12 GeV upgrade project. Progress in phenomenology and theory is flourishing as well. In this talk an overview of the latest developments in studies of TMDs will be given and newly released results, ongoing activities, as well as planned near term and future measurements will be discussed.

  17. Discrete Pearson distributions

    SciTech Connect

    Bowman, K.O. ); Shenton, L.R. ); Kastenbaum, M.A. , Basye, VA )

    1991-11-01

    These distributions are generated by a first order recursive scheme which equates the ratio of successive probabilities to the ratio of two corresponding quadratics. The use of a linearized form of this model will produce equations in the unknowns matched by an appropriate set of moments (assumed to exist). Given the moments we may find valid solutions. These are two cases; (1) distributions defined on the non-negative integers (finite or infinite) and (2) distributions defined on negative integers as well. For (1), given the first four moments, it is possible to set this up as equations of finite or infinite degree in the probability of a zero occurrence, the sth component being a product of s ratios of linear forms in this probability in general. For (2) the equation for the zero probability is purely linear but may involve slowly converging series; here a particular case is the discrete normal. Regions of validity are being studied. 11 refs.

  18. Distributed data transmitter

    DOEpatents

    Brown, Kenneth Dewayne; Dunson, David

    2008-06-03

    A distributed data transmitter (DTXR) which is an adaptive data communication microwave transmitter having a distributable architecture of modular components, and which incorporates both digital and microwave technology to provide substantial improvements in physical and operational flexibility. The DTXR has application in, for example, remote data acquisition involving the transmission of telemetry data across a wireless link, wherein the DTXR is integrated into and utilizes available space within a system (e.g., a flight vehicle). In a preferred embodiment, the DTXR broadly comprises a plurality of input interfaces; a data modulator; a power amplifier; and a power converter, all of which are modularly separate and distinct so as to be substantially independently physically distributable and positionable throughout the system wherever sufficient space is available.

  19. Distributed data transmitter

    DOEpatents

    Brown, Kenneth Dewayne; Dunson, David

    2006-08-08

    A distributed data transmitter (DTXR) which is an adaptive data communication microwave transmitter having a distributable architecture of modular components, and which incorporates both digital and microwave technology to provide substantial improvements in physical and operational flexibility. The DTXR has application in, for example, remote data acquisition involving the transmission of telemetry data across a wireless link, wherein the DTXR is integrated into and utilizes available space within a system (e.g., a flight vehicle). In a preferred embodiment, the DTXR broadly comprises a plurality of input interfaces; a data modulator; a power amplifier; and a power converter, all of which are modularly separate and distinct so as to be substantially independently physically distributable and positionable throughout the system wherever sufficient space is available.

  20. Distributed Sensors Simulator

    2003-08-30

    The Distributed Sensors Simulator (DSS) is an infrastructure that allows the user to debug and test software for distributed sensor networks without the commitment inherent in using hardware. The flexibility of DSS allows developers and researchers to investigate topological, phenomenological, networking, robustness, and scaling issues; explore arbitrary algorithms for DSNs; and is particularly useful as a proof-of-concept tool. The user provides data on node location and specifications, defines event phenomena, and plugs in the application(s)more » to run. DSS in turn provides the virtual environmental embedding — but exposed to the user like no true embedding could ever be.« less

  1. Program for standard statistical distributions

    NASA Technical Reports Server (NTRS)

    Falls, L. W.

    1972-01-01

    Development of procedure to describe frequency distributions involved in statistical theory is discussed. Representation of frequency distributions by first order differential equation is presented. Classification of various types of distributions based on Pearson parameters is analyzed.

  2. 76 FR 42768 - Capital Distribution

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-19

    ... Office of Thrift Supervision Capital Distribution AGENCY: Office of Thrift Supervision (OTS), Treasury... concerning the following information collection. Title of Proposal: Capital Distribution. OMB Number: 1550..., the information provides the OTS with a mechanism for monitoring capital distributions since...

  3. Distribution of Childrearing Demands.

    ERIC Educational Resources Information Center

    Zimmerman, Judith D.; And Others

    The tools of economic analysis were applied to demographic data in order to develop a social indicator measuring the extent of inequality in the distribution of childrearing responsibility in households from 1940 to 1980. With data drawn from the Current Population Survey of the Bureau of the Census, a "demand intensity" measure was developed.…

  4. Density distributions in nuclei

    NASA Astrophysics Data System (ADS)

    Strutinsky, V. M.; Magner, A. G.; Denisov, V. Yu.

    1985-03-01

    Density distribution across the nuclear surface is obtained in the approximation of relatively sharp nuclear edge. It is used to determine dynamical parts of the density relevant to density vibration resonances. Results of the simple calculations are in close agreement with detailed microscopic theories.

  5. Prototyping distributed simulation networks

    NASA Technical Reports Server (NTRS)

    Doubleday, Dennis L.

    1990-01-01

    Durra is a declarative language designed to support application-level programming. The use of Durra is illustrated to describe a simple distributed application: a simulation of a collection of networked vehicle simulators. It is shown how the language is used to describe the application, its components and structure, and how the runtime executive provides for the execution of the application.

  6. Momentum distributions: An overview

    NASA Astrophysics Data System (ADS)

    Sokol, P. E.; Silver, R. N.; Clark, J. W.

    There have been several excellent reviews of momentum-distribution research in particular subject areas of physics such as electronic systems and nuclear systems. However, it is the commonality of interests, difficulties, and prospects across all of physics, along with certain pivotal advances, which led to the organization of an interdisciplinary Workshop on Momentum Distributions held at Argonne National Laboratory on 24 and 26 October 1988. The purpose of this overview is to explain why scientists with such diverse backgrounds were brought together at this meeting, to introduce and discuss the common elements of momentum-distribution studies, and to establish a common language. We hope to facilitate an appreciation of the more specialized articles which follow in these proceedings. We begin by summarizing the general properties of momentum distributions. Differences and similarities of atomic, electronic, and nuclear many-body systems are examined, in terms of characteristic lengths and energies, relative importance of exchange, and the nature of the two-particle interactions. We continue with a brief commentary on the microscopic methods used to calculate n(p) from first principles.

  7. Aerosol distribution apparatus

    DOEpatents

    Hanson, W.D.

    An apparatus for uniformly distributing an aerosol to a plurality of filters mounted in a plenum, wherein the aerosol and air are forced through a manifold system by means of a jet pump and released into the plenum through orifices in the manifold. The apparatus allows for the simultaneous aerosol-testing of all the filters in the plenum.

  8. Age Distribution of Groundwater

    NASA Astrophysics Data System (ADS)

    Morgenstern, U.; Daughney, C. J.

    2012-04-01

    Groundwater at the discharge point comprises a mixture of water from different flow lines with different travel time and therefore has no discrete age but an age distribution. The age distribution can be assessed by measuring how a pulse shaped tracer moves through the groundwater system. Detection of the time delay and the dispersion of the peak in the groundwater compared to the tracer input reveals the mean residence time and the mixing parameter. Tritium from nuclear weapons testing in the early 1960s resulted in a peak-shaped tritium input to the whole hydrologic system on earth. Tritium is the ideal tracer for groundwater because it is an isotope of hydrogen and therefore is part of the water molecule. Tritium time series data that encompass the passage of the bomb tritium pulse through the groundwater system in all common hydrogeologic situations in New Zealand demonstrate a semi-systematic pattern between age distribution parameters and hydrologic situation. The data in general indicate high fraction of mixing, but in some cases also indicate high piston flow. We will show that still, 45 years after the peak of the bomb tritium, it is possible to assess accurately the parameters of age distributions by measuring the tail of the bomb tritium.

  9. Industrial power distribution

    SciTech Connect

    Sorrells, M.A.

    1990-01-01

    This paper is a broad overview of industrial power distribution. Primary focus will be on selection of the various low voltage components to achieve the end product. Emphasis will be on the use of national standards to ensure a safe and well designed installation.

  10. Distributed fuzzy system modeling

    SciTech Connect

    Pedrycz, W.; Chi Fung Lam, P.; Rocha, A.F.

    1995-05-01

    The paper introduces and studies an idea of distributed modeling treating it as a new paradigm of fuzzy system modeling and analysis. This form of modeling is oriented towards developing individual (local) fuzzy models for specific modeling landmarks (expressed as fuzzy sets) and determining the essential logical relationships between these local models. The models themselves are implemented in the form of logic processors being regarded as specialized fuzzy neural networks. The interaction between the processors is developed either in an inhibitory or excitatory way. In more descriptive way, the distributed model can be sought as a collection of fuzzy finite state machines with their individual local first or higher order memories. It is also clarified how the concept of distributed modeling narrows down a gap between purely numerical (quantitative) models and the qualitative ones originated within the realm of Artificial Intelligence. The overall architecture of distributed modeling is discussed along with the detailed learning schemes. The results of extensive simulation experiments are provided as well. 17 refs.

  11. Distributive Education. Selling. Curriculum.

    ERIC Educational Resources Information Center

    Lankford, Dave; Comte, Don

    Nineteen lesson plans on selling are presented in this performance-based curriculum unit for distributive education. This unit is self-contained and consists of the following components: introduction (provides overview of unit content and describes why mastery of the objectives is important); performance objectives; pre-assessment instrument…

  12. Distributed analysis in ATLAS

    NASA Astrophysics Data System (ADS)

    Dewhurst, A.; Legger, F.

    2015-12-01

    The ATLAS experiment accumulated more than 140 PB of data during the first run of the Large Hadron Collider (LHC) at CERN. The analysis of such an amount of data is a challenging task for the distributed physics community. The Distributed Analysis (DA) system of the ATLAS experiment is an established and stable component of the ATLAS distributed computing operations. About half a million user jobs are running daily on DA resources, submitted by more than 1500 ATLAS physicists. The reliability of the DA system during the first run of the LHC and the following shutdown period has been high thanks to the continuous automatic validation of the distributed analysis sites and the user support provided by a dedicated team of expert shifters. During the LHC shutdown, the ATLAS computing model has undergone several changes to improve the analysis workflows, including the re-design of the production system, a new analysis data format and event model, and the development of common reduction and analysis frameworks. We report on the impact such changes have on the DA infrastructure, describe the new DA components, and include recent performance measurements.

  13. Multiagent distributed watershed management

    NASA Astrophysics Data System (ADS)

    Giuliani, M.; Castelletti, A.; Amigoni, F.; Cai, X.

    2012-04-01

    Deregulation and democratization of water along with increasing environmental awareness are challenging integrated water resources planning and management worldwide. The traditional centralized approach to water management, as described in much of water resources literature, is often unfeasible in most of the modern social and institutional contexts. Thus it should be reconsidered from a more realistic and distributed perspective, in order to account for the presence of multiple and often independent Decision Makers (DMs) and many conflicting stakeholders. Game theory based approaches are often used to study these situations of conflict (Madani, 2010), but they are limited to a descriptive perspective. Multiagent systems (see Wooldridge, 2009), instead, seem to be a more suitable paradigm because they naturally allow to represent a set of self-interested agents (DMs and/or stakeholders) acting in a distributed decision process at the agent level, resulting in a promising compromise alternative between the ideal centralized solution and the actual uncoordinated practices. Casting a water management problem in a multiagent framework allows to exploit the techniques and methods that are already available in this field for solving distributed optimization problems. In particular, in Distributed Constraint Satisfaction Problems (DCSP, see Yokoo et al., 2000), each agent controls some variables according to his own utility function but has to satisfy inter-agent constraints; while in Distributed Constraint Optimization Problems (DCOP, see Modi et al., 2005), the problem is generalized by introducing a global objective function to be optimized that requires a coordination mechanism between the agents. In this work, we apply a DCSP-DCOP based approach to model a steady state hypothetical watershed management problem (Yang et al., 2009), involving several active human agents (i.e. agents who make decisions) and reactive ecological agents (i.e. agents representing

  14. Bounding species distribution models

    USGS Publications Warehouse

    Stohlgren, T.J.; Jarnevich, C.S.; Esaias, W.E.; Morisette, J.T.

    2011-01-01

    Species distribution models are increasing in popularity for mapping suitable habitat for species of management concern. Many investigators now recognize that extrapolations of these models with geographic information systems (GIS) might be sensitive to the environmental bounds of the data used in their development, yet there is no recommended best practice for "clamping" model extrapolations. We relied on two commonly used modeling approaches: classification and regression tree (CART) and maximum entropy (Maxent) models, and we tested a simple alteration of the model extrapolations, bounding extrapolations to the maximum and minimum values of primary environmental predictors, to provide a more realistic map of suitable habitat of hybridized Africanized honey bees in the southwestern United States. Findings suggest that multiple models of bounding, and the most conservative bounding of species distribution models, like those presented here, should probably replace the unbounded or loosely bounded techniques currently used. ?? 2011 Current Zoology.

  15. Bounding Species Distribution Models

    NASA Technical Reports Server (NTRS)

    Stohlgren, Thomas J.; Jarnevich, Cahterine S.; Morisette, Jeffrey T.; Esaias, Wayne E.

    2011-01-01

    Species distribution models are increasing in popularity for mapping suitable habitat for species of management concern. Many investigators now recognize that extrapolations of these models with geographic information systems (GIS) might be sensitive to the environmental bounds of the data used in their development, yet there is no recommended best practice for "clamping" model extrapolations. We relied on two commonly used modeling approaches: classification and regression tree (CART) and maximum entropy (Maxent) models, and we tested a simple alteration of the model extrapolations, bounding extrapolations to the maximum and minimum values of primary environmental predictors, to provide a more realistic map of suitable habitat of hybridized Africanized honey bees in the southwestern United States. Findings suggest that multiple models of bounding, and the most conservative bounding of species distribution models, like those presented here, should probably replace the unbounded or loosely bounded techniques currently used [Current Zoology 57 (5): 642-647, 2011].

  16. Distributed Visualization Project

    NASA Technical Reports Server (NTRS)

    Craig, Douglas; Conroy, Michael; Kickbusch, Tracey; Mazone, Rebecca

    2016-01-01

    Distributed Visualization allows anyone, anywhere to see any simulation at any time. Development focuses on algorithms, software, data formats, data systems and processes to enable sharing simulation-based information across temporal and spatial boundaries without requiring stakeholders to possess highly-specialized and very expensive display systems. It also introduces abstraction between the native and shared data, which allows teams to share results without giving away proprietary or sensitive data. The initial implementation of this capability is the Distributed Observer Network (DON) version 3.1. DON 3.1 is available for public release in the NASA Software Store (https://software.nasa.gov/software/KSC-13775) and works with version 3.0 of the Model Process Control specification (an XML Simulation Data Representation and Communication Language) to display complex graphical information and associated Meta-Data.

  17. Radio frequency distribution assembly

    NASA Astrophysics Data System (ADS)

    Culley, K. M.

    The Naval Research Laboratory (NRL) Radio Frequency Distribution Assembly (RFDA) is an interface between the Sperry four-channel, fast-switching synthesizer and the EF-111 jamming system antenna ports. The RFDS is a sophisticated, high-speed RF interface designed to convert the banded outputs of the four-channel synthesizer (16 ports) to 36 ports which represent six ordinal directions of arrival (DOA) for the EF-111 jamming system. The RFDS will distribute the RF signals while providing controlled RF amplitudes to simulate the antenna patterns of the EF-111 Electronic Warfare (EW) system. The simulation of the arrival angles which appear between the ordinal directions is performed by controlling the amplitude of the RF signal from the DOA channels. The RFDA is capable of operating over the frequency range of 500MHz to 18GHz, and can rapidly switch between varying frequencies and attenuation levels.

  18. Distributed environmental control

    NASA Technical Reports Server (NTRS)

    Cleveland, Gary A.

    1992-01-01

    We present an architecture of distributed, independent control agents designed to work with the Computer Aided System Engineering and Analysis (CASE/A) simulation tool. CASE/A simulates behavior of Environmental Control and Life Support Systems (ECLSS). We describe a lattice of agents capable of distributed sensing and overcoming certain sensor and effector failures. We address how the architecture can achieve the coordinating functions of a hierarchical command structure while maintaining the robustness and flexibility of independent agents. These agents work between the time steps of the CASE/A simulation tool to arrive at command decisions based on the state variables maintained by CASE/A. Control is evaluated according to both effectiveness (e.g., how well temperature was maintained) and resource utilization (the amount of power and materials used).

  19. Properly Understanding the Impacts of Distributed Resources on Distribution Systems

    SciTech Connect

    Rizy, D Tom; Li, Fangxing; Li, Huijuan; Adhikari, Sarina; Kueck, John D

    2010-01-01

    The subject paper discusses important impacts of distributed resources on distribution networks and feeders. These include capacity, line losses, voltage regulation, and central system support (such as volt/var via central generators and substation) as the number, placement and penetration levels of distributed resources are varied. Typically, the impacts of distributed resources on the distribution system are studied by using steady-state rather than dynamic analysis tools. However, the response time and transient impacts of both system equipment (such as substation/feeder capacitors) and distributed resources needs to be taken into account and only dynamic analysis will provide the full impact results. ORNL is wrapping up a study of distributed resources interconnected to a large distribution system considering the above variables. A report of the study and its results will be condensed into a paper for this panel session. The impact of distributed resources will vary as the penetration level reaches the capacity of the distribution feeder/system. The question is how high of a penetration of distributed resource can be accommodated on the distribution feeder/system without any major changes to system operation, design and protection. The impacts most surely will vary depending upon load composition, distribution and level. Also, it is expected that various placement of distributed resources will impact the distribution system differently.

  20. Fiber distributed feedback laser

    NASA Technical Reports Server (NTRS)

    Elachi, C.; Evans, G. A.; Yeh, C. (Inventor)

    1976-01-01

    Utilizing round optical fibers as communication channels in optical communication networks presents the problem of obtaining a high efficiency coupling between the optical fiber and the laser. A laser is made an integral part of the optical fiber channel by either diffusing active material into the optical fiber or surrounding the optical fiber with the active material. Oscillation within the active medium to produce lasing action is established by grating the optical fiber so that distributed feedback occurs.

  1. Symmetric generalized binomial distributions

    SciTech Connect

    Bergeron, H.; Curado, E. M. F.; Gazeau, J. P.; Rodrigues, Ligia M. C. S. E-mail: evaldo@cbpf.br E-mail: ligia@cbpf.br

    2013-12-15

    In two recent articles, we have examined a generalization of the binomial distribution associated with a sequence of positive numbers, involving asymmetric expressions of probabilities that break the symmetry win-loss. We present in this article another generalization (always associated with a sequence of positive numbers) that preserves the symmetry win-loss. This approach is also based on generating functions and presents constraints of non-negativeness, similar to those encountered in our previous articles.

  2. Structure functions and parton distributions

    SciTech Connect

    Olness, F.; Tung, Wu-Ki

    1991-04-01

    Activities of the structure functions and parton distributions group is summarized. The impact of scheme-dependence of parton distributions (especially sea-quarks and gluons) on the quantitative formulation of the QCD parton model is highlighted. Recent progress on the global analysis of parton distributions is summarized. Issues on the proper use of the next-to-leading parton distributions are stressed.

  3. Distributed Education, Expertise, and Cognition.

    ERIC Educational Resources Information Center

    Saba, Farhad

    2000-01-01

    Discusses the term distributed education and its relationship to distance education. Topics include distributed training on corporate intranets; distributed expertise, which refers to the use of mediated communication for education and training by experts in different locations; and distributed, or situated, cognition, which would include…

  4. A distributable APSE

    NASA Technical Reports Server (NTRS)

    Taft, Tucker, S.

    1986-01-01

    A distributed Ada program library is a key element in a distributed Ada Program Support Environment (APSE). To implement this successfully, the program library universe as defined by the Ada Reference Manual must be broken up into independently manageable pieces. This in turn requires the support of a distributed database system, as well as a mechanism for identifying compilation units, linkable subprograms, and Ada types in a decentralized way, to avoid falling victim to the bottlenecks of a global database and/or global unique-identifier manager. It was found that the ability to decentralize Ada program library activity is a major advantage in the management of large Ada programs. Currently, there are 18 resource-catalog revision sets, each in its own Host Interface (HIF) partition, plus 18 partitions for testing each of these, plus 11 partitions for the top-level compiler/linker/program library manager components. Compiling and other development work can proceed in parallel in each of these partitions, without suffering the performance bottlenecks of global locks or global unique-identifier generation.

  5. The Distributed Auditory Cortex

    PubMed Central

    Winer, Jeffery A.; Lee, Charles C.

    2009-01-01

    A synthesis of cat auditory cortex (AC) organization is presented in which the extrinsic and intrinsic connections interact to derive a unified profile of the auditory stream and use it to direct and modify cortical and subcortical information flow. Thus, the thalamocortical input provides essential sensory information about peripheral stimulus events, which AC redirects locally for feature extraction, and then conveys to parallel auditory, multisensory, premotor, limbic, and cognitive centers for further analysis. The corticofugal output influences areas as remote as the pons and the cochlear nucleus, structures whose effects upon AC are entirely indirect, and has diverse roles in the transmission of information through the medial geniculate body and inferior colliculus. The distributed AC is thus construed as a functional network in which the auditory percept is assembled for subsequent redistribution in sensory, premotor, and cognitive streams contingent on the derived interpretation of the acoustic events. The confluence of auditory and multisensory streams likely precedes cognitive processing of sound. The distributed AC constitutes the largest and arguably the most complete representation of the auditory world. Many facets of this scheme may apply in rodent and primate AC as well. We propose that the distributed auditory cortex contributes to local processing regimes in regions as disparate as the frontal pole and the cochlear nucleus to construct the acoustic percept. PMID:17329049

  6. GASIFICATION FOR DISTRIBUTED GENERATION

    SciTech Connect

    Ronald C. Timpe; Michael D. Mann; Darren D. Schmidt

    2000-05-01

    A recent emphasis in gasification technology development has been directed toward reduced-scale gasifier systems for distributed generation at remote sites. The domestic distributed power generation market over the next decade is expected to be 5-6 gigawatts per year. The global increase is expected at 20 gigawatts over the next decade. The economics of gasification for distributed power generation are significantly improved when fuel transport is minimized. Until recently, gasification technology has been synonymous with coal conversion. Presently, however, interest centers on providing clean-burning fuel to remote sites that are not necessarily near coal supplies but have sufficient alternative carbonaceous material to feed a small gasifier. Gasifiers up to 50 MW are of current interest, with emphasis on those of 5-MW generating capacity. Internal combustion engines offer a more robust system for utilizing the fuel gas, while fuel cells and microturbines offer higher electric conversion efficiencies. The initial focus of this multiyear effort was on internal combustion engines and microturbines as more realistic near-term options for distributed generation. In this project, we studied emerging gasification technologies that can provide gas from regionally available feedstock as fuel to power generators under 30 MW in a distributed generation setting. Larger-scale gasification, primarily coal-fed, has been used commercially for more than 50 years to produce clean synthesis gas for the refining, chemical, and power industries. Commercial-scale gasification activities are under way at 113 sites in 22 countries in North and South America, Europe, Asia, Africa, and Australia, according to the Gasification Technologies Council. Gasification studies were carried out on alfalfa, black liquor (a high-sodium waste from the pulp industry), cow manure, and willow on the laboratory scale and on alfalfa, black liquor, and willow on the bench scale. Initial parametric tests

  7. Planning Systems for Distributed Operations

    NASA Technical Reports Server (NTRS)

    Maxwell, Theresa G.

    2002-01-01

    This viewgraph representation presents an overview of the mission planning process involving distributed operations (such as the International Space Station (ISS)) and the computer hardware and software systems needed to support such an effort. Topics considered include: evolution of distributed planning systems, ISS distributed planning, the Payload Planning System (PPS), future developments in distributed planning systems, Request Oriented Scheduling Engine (ROSE) and Next Generation distributed planning systems.

  8. Factors affecting distributed system security

    SciTech Connect

    Nessett, D.M.

    1985-11-13

    Recent work examining distributed system security requirements is critiqued. A notion of trust based on distributed system topology and distributed system node evaluation levels proposed in that work is shown to be deficient. The notion fails to make allowances for the distributed system physical security environment, security factors related to the management of distributed systems by more than one jurisdictive authority and interactions that can occur between nodes supporting different mandatory and discretionary security mechanisms.

  9. Representation of orientation distributions

    SciTech Connect

    Wenk, H.R.; Kocks, U.F.

    1985-01-01

    This paper illustrates the principles presented with a particular experimental texture: from the surface layer of a copper polycrystal cold-rolled to 60% reduction in thickness. Four incomplete pole figures (200, 220, 222, and 113) were determined by x-ray diffraction in reflection geometry. The measured pole figures nearly exhibited orthorhombic symmetry (as expected), which was then strictly enforced by averaging the four quadrants of the pole figure. The orientation distribution function was obtained using the expansion in spherical harmonics (with only even-order coefficients up to l = 18).

  10. Distributed Optimization System

    DOEpatents

    Hurtado, John E.; Dohrmann, Clark R.; Robinett, III, Rush D.

    2004-11-30

    A search system and method for controlling multiple agents to optimize an objective using distributed sensing and cooperative control. The search agent can be one or more physical agents, such as a robot, and can be software agents for searching cyberspace. The objective can be: chemical sources, temperature sources, radiation sources, light sources, evaders, trespassers, explosive sources, time dependent sources, time independent sources, function surfaces, maximization points, minimization points, and optimal control of a system such as a communication system, an economy, a crane, and a multi-processor computer.

  11. Distributed computing systems programme

    SciTech Connect

    Duce, D.

    1984-01-01

    Publication of this volume coincides with the completion of the U.K. Science and Engineering Research Council's coordinated programme of research in Distributed Computing Systems (DCS) which ran from 1977 to 1984. The volume is based on presentations made at the programme's final conference. The first chapter explains the origins and history of DCS and gives an overview of the programme and its achievements. The remaining sixteen chapters review particular research themes (including imperative and declarative languages, and performance modelling), and describe particular research projects in technical areas including local area networks, design, development and analysis of concurrent systems, parallel algorithm design, functional programming and non-von Neumann computer architectures.

  12. Coping with distributed computing

    SciTech Connect

    Cormell, L.

    1992-09-01

    The rapid increase in the availability of high performance, cost-effective RISC/UNIX workstations has been both a blessing and a curse. The blessing of having extremely powerful computing engines available on the desk top is well-known to many users. The user has tremendous freedom, flexibility, and control of his environment. That freedom can, however, become the curse of distributed computing. The user must become a system manager to some extent, he must worry about backups, maintenance, upgrades, etc. Traditionally these activities have been the responsibility of a central computing group. The central computing group, however, may find that it can no longer provide all of the traditional services. With the plethora of workstations now found on so many desktops throughout the entire campus or lab, the central computing group may be swamped by support requests. This talk will address several of these computer support and management issues by providing some examples of the approaches taken at various HEP institutions. In addition, a brief review of commercial directions or products for distributed computing and management will be given.

  13. Vascular Distribution of Nanomaterials

    PubMed Central

    Stapleton, Phoebe A.; Nurkiewicz, Timothy R.

    2014-01-01

    Once considered primarily occupational, novel nanotechnology innovation and application has led to widespread domestic use and intentional biomedical exposures. With these exciting advances, the breadth and depth of toxicological considerations must also be expanded. The vascular system interacts with every tissue in the body, striving to homeostasis. Engineered nanomaterials (ENM) have been reported to distribute in many different organs and tissues. However, these observations have tended to use approaches requiring tissue homogenization and/or gross organ analyses. These techniques, while effective in establishing presence, preclude an exact determination of where ENM are deposited within a tissue. It is necessary to identify this exact distribution and deposition of ENM throughout the cardiovascular system, with respect to vascular hemodynamics and in vivo/ in vitro ENM modifications taken into account if nanotechnology is to achieve its full potential. Distinct levels of the vasculature will first be described as individual compartments. Then the vasculature will be considered as a whole. These unique compartments and biophysical conditions will be discussed in terms of their propensity to favor ENM deposition. Understanding levels of the vasculature will also be discussed. Ultimately, future studies must verify the mechanisms speculated on and presented herein. PMID:24777845

  14. Models of distributive justice.

    PubMed

    Wolff, Jonathan

    2007-01-01

    Philosophical disagreement about justice rages over at least two questions. The most immediate is a substantial question, concerning the conditions under which particular distributive arrangements can be said to be just or unjust. The second, deeper, question concerns the nature of justice itself. What is justice? Here we can distinguish three views. First, justice as mutual advantage sees justice as essentially a matter of the outcome of a bargain. There are times when two parties can both be better off by making some sort of agreement. Justice, on this view, concerns the distribution of the benefits and burdens of the agreement. Second, justice as reciprocity takes a different approach, looking not at bargaining but at the idea of a fair return or just price, attempting to capture the idea of justice as equal exchange. Finally justice as impartiality sees justice as 'taking the other person's point of view' asking 'how would you like it if it happened to you?' Each model has significantly different consequences for the question of when issues of justice arise and how they should be settled. It is interesting to consider whether any of these models of justice could regulate behaviour between non-human animals.

  15. PULSE AMPLITUDE DISTRIBUTION RECORDER

    DOEpatents

    Cowper, G.

    1958-08-12

    A device is described for automatica1ly recording pulse annplitude distribution received from a counter. The novelty of the device consists of the over-all arrangement of conventional circuit elements to provide an easy to read permanent record of the pulse amplitude distribution during a certain time period. In the device a pulse analyzer separates the pulses according to annplitude into several channels. A scaler in each channel counts the pulses and operates a pen marker positioned over a drivable recorder sheet. Since the scalers in each channel have the sanne capacity, the control circuitry permits counting of the incoming pulses until one scaler reaches capacity, whereupon the input is removed and an internal oscillator supplies the necessary pulses to fill up the other scalers. Movement of the chart sheet is initiated wben the first scaler reaches capacity to thereby give a series of marks at spacings proportional to the time required to fill the remaining scalers, and accessory equipment marks calibration points on the recorder sheet to facilitate direct reading of the number of external pulses supplied to each scaler.

  16. Automated Gas Distribution System

    NASA Astrophysics Data System (ADS)

    Starke, Allen; Clark, Henry

    2012-10-01

    The cyclotron of Texas A&M University is one of the few and prized cyclotrons in the country. Behind the scenes of the cyclotron is a confusing, and dangerous setup of the ion sources that supplies the cyclotron with particles for acceleration. To use this machine there is a time consuming, and even wasteful step by step process of switching gases, purging, and other important features that must be done manually to keep the system functioning properly, while also trying to maintain the safety of the working environment. Developing a new gas distribution system to the ion source prevents many of the problems generated by the older manually setup process. This developed system can be controlled manually in an easier fashion than before, but like most of the technology and machines in the cyclotron now, is mainly operated based on software programming developed through graphical coding environment Labview. The automated gas distribution system provides multi-ports for a selection of different gases to decrease the amount of gas wasted through switching gases, and a port for the vacuum to decrease the amount of time spent purging the manifold. The Labview software makes the operation of the cyclotron and ion sources easier, and safer for anyone to use.

  17. Distributed System Design Checklist

    NASA Technical Reports Server (NTRS)

    Hall, Brendan; Driscoll, Kevin

    2014-01-01

    This report describes a design checklist targeted to fault-tolerant distributed electronic systems. Many of the questions and discussions in this checklist may be generally applicable to the development of any safety-critical system. However, the primary focus of this report covers the issues relating to distributed electronic system design. The questions that comprise this design checklist were created with the intent to stimulate system designers' thought processes in a way that hopefully helps them to establish a broader perspective from which they can assess the system's dependability and fault-tolerance mechanisms. While best effort was expended to make this checklist as comprehensive as possible, it is not (and cannot be) complete. Instead, we expect that this list of questions and the associated rationale for the questions will continue to evolve as lessons are learned and further knowledge is established. In this regard, it is our intent to post the questions of this checklist on a suitable public web-forum, such as the NASA DASHLink AFCS repository. From there, we hope that it can be updated, extended, and maintained after our initial research has been completed.

  18. Atlas Distributed Analysis Tools

    NASA Astrophysics Data System (ADS)

    de La Hoz, Santiago Gonzalez; Ruiz, Luis March; Liko, Dietrich

    2008-06-01

    The ATLAS production system has been successfully used to run production of simulation data at an unprecedented scale. Up to 10000 jobs were processed in one day. The experiences obtained operating the system on several grid flavours was essential to perform a user analysis using grid resources. First tests of the distributed analysis system were then performed. In the preparation phase data was registered in the LHC File Catalog (LFC) and replicated in external sites. For the main test, few resources were used. All these tests are only a first step towards the validation of the computing model. The ATLAS management computing board decided to integrate the collaboration efforts in distributed analysis in only one project, GANGA. The goal is to test the reconstruction and analysis software in a large scale Data production using Grid flavors in several sites. GANGA allows trivial switching between running test jobs on a local batch system and running large-scale analyses on the Grid; it provides job splitting and merging, and includes automated job monitoring and output retrieval.

  19. Distributed Active Archive Center

    NASA Technical Reports Server (NTRS)

    Bodden, Lee; Pease, Phil; Bedet, Jean-Jacques; Rosen, Wayne

    1993-01-01

    The Goddard Space Flight Center Version 0 Distributed Active Archive Center (GSFC V0 DAAC) is being developed to enhance and improve scientific research and productivity by consolidating access to remote sensor earth science data in the pre-EOS time frame. In cooperation with scientists from the science labs at GSFC, other NASA facilities, universities, and other government agencies, the DAAC will support data acquisition, validation, archive and distribution. The DAAC is being developed in response to EOSDIS Project Functional Requirements as well as from requirements originating from individual science projects such as SeaWiFS, Meteor3/TOMS2, AVHRR Pathfinder, TOVS Pathfinder, and UARS. The GSFC V0 DAAC has begun operational support for the AVHRR Pathfinder (as of April, 1993), TOVS Pathfinder (as of July, 1993) and the UARS (September, 1993) Projects, and is preparing to provide operational support for SeaWiFS (August, 1994) data. The GSFC V0 DAAC has also incorporated the existing data, services, and functionality of the DAAC/Climate, DAAC/Land, and the Coastal Zone Color Scanner (CZCS) Systems.

  20. Distribution and moments of radial error. [Rayleigh distribution - random variables

    NASA Technical Reports Server (NTRS)

    White, R. G.

    1975-01-01

    An investigation of the moments and probability distribution of the resultant of two normally distributed random variables is presented. This is the so-called generalized Rayleigh distribution which has many applications in the study of wind shear, random noise, and radar. The most general formula was derived, and two special cases were considered for which tables of the moments and probability distribution functions are included as an appendix. One of the special cases was generalized to n-dimensions.

  1. Distributed Wind Energy in Idaho

    SciTech Connect

    Gardner, John; Johnson, Kathryn; Haynes, Todd; Seifert, Gary

    2009-01-31

    This project is a research and development program aimed at furthering distributed wind technology. In particular, this project addresses some of the barriers to distributed wind energy utilization in Idaho.

  2. Distributed charging of electrical assets

    DOEpatents

    Ghosh, Soumyadip; Phan, Dung; Sharma, Mayank; Wu, Chai Wah; Xiong, Jinjun

    2016-02-16

    The present disclosure relates generally to the field of distributed charging of electrical assets. In various examples, distributed charging of electrical assets may be implemented in the form of systems, methods and/or algorithms.

  3. Distributed feedback lasers

    NASA Technical Reports Server (NTRS)

    Ladany, I.; Andrews, J. T.; Evans, G. A.

    1988-01-01

    A ridge waveguide distributed feedback laser was developed in InGaAsP. These devices have demonstrated CW output powers over 7 mW with threshold currents as low as 60 mA at 25 C. Measurements of the frequency response of these devices show a 3 dB bandwidth of about 2 GHz, which may be limited by the mount. The best devices have a single mode spectra over the entire temperature range tested with a side mode suppression of about 20 dB in both CW and pulsed modes. The design of this device, including detailed modeling of the ridge guide structure, effective index calculations, and a discussion of the grating configuration are presented. Also, the fabrication of the devices is presented in some detail, especially the fabrication of and subsequent growth over the grating. In addition, a high frequency fiber pigtailed package was designed and tested, which is a suitable prototype for a commercial package.

  4. DISTRIBUTED AMPLIFIER INCORPORATING FEEDBACK

    DOEpatents

    Bell, P.R. Jr.

    1958-10-21

    An improved distributed amplifier system employing feedback for stabilization is presented. In accordance with the disclosed invention, a signal to be amplified is applled to one end of a suitable terminated grid transmission line. At intervals along the transmission line, the signal is fed to stable, resistance-capacitance coupled amplifiers incorporating feedback loops therein. The output current from each amplifier is passed through an additional tube to minimize the electrostatic capacitance between the tube elements of the last stage of the amplifier, and fed to appropriate points on an output transmission line, similar to the grid line, but terminated at the opposite (input) end. The output taken from the unterminated end of the plate transmission line is proportional to the input voltage impressed upon the grid line.

  5. Nuclear Parton Distribution Functions

    SciTech Connect

    I. Schienbein, J.Y. Yu, C. Keppel, J.G. Morfin, F. Olness, J.F. Owens

    2009-06-01

    We study nuclear effects of charged current deep inelastic neutrino-iron scattering in the framework of a {chi}{sup 2} analysis of parton distribution functions (PDFs). We extract a set of iron PDFs which are used to compute x{sub Bj}-dependent and Q{sup 2}-dependent nuclear correction factors for iron structure functions which are required in global analyses of free nucleon PDFs. We compare our results with nuclear correction factors from neutrino-nucleus scattering models and correction factors for charged-lepton--iron scattering. We find that, except for very high x{sub Bj}, our correction factors differ in both shape and magnitude from the correction factors of the models and charged-lepton scattering.

  6. Carotenoid Distribution in Nature.

    PubMed

    Alcaíno, Jennifer; Baeza, Marcelo; Cifuentes, Víctor

    2016-01-01

    Carotenoids are naturally occurring red, orange and yellow pigments that are synthesized by plants and some microorganisms and fulfill many important physiological functions. This chapter describes the distribution of carotenoid in microorganisms, including bacteria, archaea, microalgae, filamentous fungi and yeasts. We will also focus on their functional aspects and applications, such as their nutritional value, their benefits for human and animal health and their potential protection against free radicals. The central metabolic pathway leading to the synthesis of carotenoids is described as the three following principal steps: (i) the synthesis of isopentenyl pyrophosphate and the formation of dimethylallyl pyrophosphate, (ii) the synthesis of geranylgeranyl pyrophosphate and (iii) the synthesis of carotenoids per se, highlighting the differences that have been found in several carotenogenic organisms and providing an evolutionary perspective. Finally, as an example, the synthesis of the xanthophyll astaxanthin is discussed. PMID:27485217

  7. Protocols for distributive scheduling

    NASA Technical Reports Server (NTRS)

    Richards, Stephen F.; Fox, Barry

    1993-01-01

    The increasing complexity of space operations and the inclusion of interorganizational and international groups in the planning and control of space missions lead to requirements for greater communication, coordination, and cooperation among mission schedulers. These schedulers must jointly allocate scarce shared resources among the various operational and mission oriented activities while adhering to all constraints. This scheduling environment is complicated by such factors as the presence of varying perspectives and conflicting objectives among the schedulers, the need for different schedulers to work in parallel, and limited communication among schedulers. Smooth interaction among schedulers requires the use of protocols that govern such issues as resource sharing, authority to update the schedule, and communication of updates. This paper addresses the development and characteristics of such protocols and their use in a distributed scheduling environment that incorporates computer-aided scheduling tools. An example problem is drawn from the domain of space shuttle mission planning.

  8. Distributed road assessment system

    DOEpatents

    Beer, N. Reginald; Paglieroni, David W

    2014-03-25

    A system that detects damage on or below the surface of a paved structure or pavement is provided. A distributed road assessment system includes road assessment pods and a road assessment server. Each road assessment pod includes a ground-penetrating radar antenna array and a detection system that detects road damage from the return signals as the vehicle on which the pod is mounted travels down a road. Each road assessment pod transmits to the road assessment server occurrence information describing each occurrence of road damage that is newly detected on a current scan of a road. The road assessment server maintains a road damage database of occurrence information describing the previously detected occurrences of road damage. After the road assessment server receives occurrence information for newly detected occurrences of road damage for a portion of a road, the road assessment server determines which newly detected occurrences correspond to which previously detected occurrences of road damage.

  9. Process evaluation distributed system

    NASA Technical Reports Server (NTRS)

    Moffatt, Christopher L. (Inventor)

    2006-01-01

    The distributed system includes a database server, an administration module, a process evaluation module, and a data display module. The administration module is in communication with the database server for providing observation criteria information to the database server. The process evaluation module is in communication with the database server for obtaining the observation criteria information from the database server and collecting process data based on the observation criteria information. The process evaluation module utilizes a personal digital assistant (PDA). A data display module in communication with the database server, including a website for viewing collected process data in a desired metrics form, the data display module also for providing desired editing and modification of the collected process data. The connectivity established by the database server to the administration module, the process evaluation module, and the data display module, minimizes the requirement for manual input of the collected process data.

  10. Spatially Distributed Cell Signalling

    PubMed Central

    Kholodenko, Boris N.

    2009-01-01

    Emerging evidence indicates that complex spatial gradients and (micro)domains of signalling activities arise from distinct cellular localization of opposing enzymes, such as a kinase and phosphatase, in signal transduction cascades. Often, an interacting, active form of a target protein has a lower diffusivity than an inactive form, and this leads to spatial gradients of the protein abundance in the cytoplasm. A spatially distributed signalling cascade can create step-like activation profiles, which decay at successive distances from the cell surface, assigning digital positional information to different regions in the cell. Feedback and feedforward network motifs control activity patterns, allowing signalling networks to serve as cellular devices for spatial computations. PMID:19800332

  11. Sparse distributed memory

    NASA Technical Reports Server (NTRS)

    Denning, Peter J.

    1989-01-01

    Sparse distributed memory was proposed be Pentti Kanerva as a realizable architecture that could store large patterns and retrieve them based on partial matches with patterns representing current sensory inputs. This memory exhibits behaviors, both in theory and in experiment, that resemble those previously unapproached by machines - e.g., rapid recognition of faces or odors, discovery of new connections between seemingly unrelated ideas, continuation of a sequence of events when given a cue from the middle, knowing that one doesn't know, or getting stuck with an answer on the tip of one's tongue. These behaviors are now within reach of machines that can be incorporated into the computing systems of robots capable of seeing, talking, and manipulating. Kanerva's theory is a break with the Western rationalistic tradition, allowing a new interpretation of learning and cognition that respects biology and the mysteries of individual human beings.

  12. Mediated semiquantum key distribution

    NASA Astrophysics Data System (ADS)

    Krawec, Walter O.

    2015-03-01

    In this work, we design a quantum key distribution protocol, allowing two limited semiquantum or "classical" users to establish a shared secret key with the help of a fully quantum server. A semiquantum user can prepare and measure qubits only in the computational basis and so must rely on this quantum server to produce qubits in alternative bases and also to perform alternative measurements. However, we assume that the server is untrusted and we prove the unconditional security of our protocol even in the worst case: when this quantum server is an all-powerful adversary. We also compute a lower bound of the key rate of our protocol, in the asymptotic scenario, as a function of the observed error rate in the channel, allowing us to compute the maximally tolerated error of our protocol. Our results show that a semiquantum protocol may hold similar security to a fully quantum one.

  13. CMCC Data Distribution Centre

    NASA Astrophysics Data System (ADS)

    Aloisio, Giovanni; Fiore, Sandro; Negro, A.

    2010-05-01

    The CMCC Data Distribution Centre (DDC) is the primary entry point (web gateway) to the CMCC. It is a Data Grid Portal providing a ubiquitous and pervasive way to ease data publishing, climate metadata search, datasets discovery, metadata annotation, data access, data aggregation, sub-setting, etc. The grid portal security model includes the use of HTTPS protocol for secure communication with the client (based on X509v3 certificates that must be loaded into the browser) and secure cookies to establish and maintain user sessions. The CMCC DDC is now in a pre-production phase and it is currently used only by internal users (CMCC researchers and climate scientists). The most important component already available in the CMCC DDC is the Search Engine which allows users to perform, through web interfaces, distributed search and discovery activities by introducing one or more of the following search criteria: horizontal extent (which can be specified by interacting with a geographic map), vertical extent, temporal extent, keywords, topics, creation date, etc. By means of this page the user submits the first step of the query process on the metadata DB, then, she can choose one or more datasets retrieving and displaying the complete XML metadata description (from the browser). This way, the second step of the query process is carried out by accessing to a specific XML document of the metadata DB. Finally, through the web interface, the user can access to and download (partially or totally) the data stored on the storage device accessing to OPeNDAP servers and to other available grid storage interfaces. Requests concerning datasets stored in deep storage will be served asynchronously.

  14. Hail Size Distribution Mapping

    NASA Technical Reports Server (NTRS)

    2008-01-01

    A 3-D weather radar visualization software program was developed and implemented as part of an experimental Launch Pad 39 Hail Monitor System. 3DRadPlot, a radar plotting program, is one of several software modules that form building blocks of the hail data processing and analysis system (the complete software processing system under development). The spatial and temporal mapping algorithms were originally developed through research at the University of Central Florida, funded by NASA s Tropical Rainfall Measurement Mission (TRMM), where the goal was to merge National Weather Service (NWS) Next-Generation Weather Radar (NEXRAD) volume reflectivity data with drop size distribution data acquired from a cluster of raindrop disdrometers. In this current work, we adapted these algorithms to process data from a cluster of hail disdrometers positioned around Launch Pads 39A or 39B, along with the corresponding NWS radar data. Radar data from all NWS NEXRAD sites is archived at the National Climatic Data Center (NCDC). That data can be readily accessed at . 3DRadPlot plots Level III reflectivity data at four scan elevations (this software is available at Open Channel Software, ). By using spatial and temporal interpolation/extrapolation based on hydrometeor fall dynamics, we can merge the hail disdrometer array data coupled with local Weather Surveillance Radar-1988, Doppler (WSR-88D) radial velocity and reflectivity data into a 4-D (3-D space and time) picture of hail size distributions. Hail flux maps can then be generated and used for damage prediction and assessment over specific surfaces corresponding to structures within the disdrometer array volume. Immediately following a hail storm, specific damage areas and degree of damage can be identified for inspection crews.

  15. The Saguaro distributed operating system

    NASA Astrophysics Data System (ADS)

    Andrews, Gregory R.; Schlichting, Richard D.

    1989-05-01

    The progress achieved over the final year of the Saguaro distributed operating system project is presented. The primary achievements were in related research, including SR distributed programming language, the MLP system for constructing distributed mixed-language programs, the Psync interprocess communication mechanism, a configurable operating system kernal called the x-kernal, and the development of language mechanisms for performing failure handling in distributed programming languages.

  16. Distributed Simulation for Space Exploration

    NASA Technical Reports Server (NTRS)

    Crues, Edwin Z.

    2006-01-01

    This viewgraph presentation reviews the use of simulation and modeling in preparation for the planned exploration initiatives. The Exploration Systems Mission Directorate (EMSD) Integrated Modeling and Simulation (IM&S) team strategy encompasses a wide spectrum of simulation and modeling policies and technologies. One prominent technology is distributed simulation. The DIstributed Simulation (DIS),a collaborative simulation project with international participation (US and Japan) is reviewed as an example of distributed simulation development. The Distributed Space Exploration Simulation (DSES) is another example of distributed simulation that is described

  17. Correction of Distributed Optical Aberrations

    SciTech Connect

    Baker, K; Olivier, S; Carrano, C; Phillion, D

    2006-02-12

    The objective of this project was to demonstrate the use of multiple distributed deformable mirrors (DMs) to improve the performance of optical systems with distributed aberrations. This concept is expected to provide dramatic improvement in the optical performance of systems in applications where the aberrations are distributed along the optical path or within the instrument itself. Our approach used multiple actuated DMs distributed to match the aberration distribution. The project developed the algorithms necessary to determine the required corrections and simulate the performance of these multiple DM systems.

  18. Distributed visualization framework architecture

    NASA Astrophysics Data System (ADS)

    Mishchenko, Oleg; Raman, Sundaresan; Crawfis, Roger

    2010-01-01

    An architecture for distributed and collaborative visualization is presented. The design goals of the system are to create a lightweight, easy to use and extensible framework for reasearch in scientific visualization. The system provides both single user and collaborative distributed environment. System architecture employs a client-server model. Visualization projects can be synchronously accessed and modified from different client machines. We present a set of visualization use cases that illustrate the flexibility of our system. The framework provides a rich set of reusable components for creating new applications. These components make heavy use of leading design patterns. All components are based on the functionality of a small set of interfaces. This allows new components to be integrated seamlessly with little to no effort. All user input and higher-level control functionality interface with proxy objects supporting a concrete implementation of these interfaces. These light-weight objects can be easily streamed across the web and even integrated with smart clients running on a user's cell phone. The back-end is supported by concrete implementations wherever needed (for instance for rendering). A middle-tier manages any communication and synchronization with the proxy objects. In addition to the data components, we have developed several first-class GUI components for visualization. These include a layer compositor editor, a programmable shader editor, a material editor and various drawable editors. These GUI components interact strictly with the interfaces. Access to the various entities in the system is provided by an AssetManager. The asset manager keeps track of all of the registered proxies and responds to queries on the overall system. This allows all user components to be populated automatically. Hence if a new component is added that supports the IMaterial interface, any instances of this can be used in the various GUI components that work with this

  19. Vacillation Made Easy: Distribution, Re-distribution, and Un-distribution of DOPL-based Processing

    NASA Technical Reports Server (NTRS)

    Burleigh, Scott

    1993-01-01

    Distributed Objects Protocol Layer, or DOPL, Provides a simple and general data communication abstraction that can support the distribution of C++ applications software functionality among an arbitrary collection of processors. The purposed of the abstraction is to minimize the cost of revising processing distribution decisions throughout the software development cycle, including after software has beed delivered to users.

  20. Distributed ultrafast fibre laser

    PubMed Central

    Liu, Xueming; Cui, Yudong; Han, Dongdong; Yao, Xiankun; Sun, Zhipei

    2015-01-01

    A traditional ultrafast fibre laser has a constant cavity length that is independent of the pulse wavelength. The investigation of distributed ultrafast (DUF) lasers is conceptually and technically challenging and of great interest because the laser cavity length and fundamental cavity frequency are changeable based on the wavelength. Here, we propose and demonstrate a DUF fibre laser based on a linearly chirped fibre Bragg grating, where the total cavity length is linearly changeable as a function of the pulse wavelength. The spectral sidebands in DUF lasers are enhanced greatly, including the continuous-wave (CW) and pulse components. We observe that all sidebands of the pulse experience the same round-trip time although they have different round-trip distances and refractive indices. The pulse-shaping of the DUF laser is dominated by the dissipative processes in addition to the phase modulations, which makes our ultrafast laser simple and stable. This laser provides a simple, stable, low-cost, ultrafast-pulsed source with controllable and changeable cavity frequency. PMID:25765454

  1. Intraplacental retinol distribution.

    PubMed

    Saunders, Cláudia; Leal, Maria Do Carmo; Flores, Hernando; Soares, Alexandre Gonçalves; De Lima, Ana Paula Pereira Thiapó; Leite, Paula Costa; Gomes, Mirian Martins; De Souza Júnior, Paulo Roberto Borges; Ramalho, Rejane Andréa

    2005-12-01

    With the objective of evaluating intraplacental vitamin A distribution, 234 placental samples were collected, corresponding to six samples from each of the placentas analyzed: two from the lateral maternal portion, one from the central maternal portion, two from the lateral fetal portion, and one from the central fetal portion. Samples were obtained from 39 adult puerperal mothers with low-risk pregnancies, without vitamin A deficiency or night blindness. Retinol content determination was achieved through spectrophotometry. Retinol values obtained for each region were correlated with the most probable value for each placenta (P < 0.001). Despite differences in retinol content between samples, statistical data analysis showed that intra-tissue variation had no influence on the conversion of data into information. Consequently, any portion of the placenta may be used for retinol level determination purposes, due to the correlation between all portions and the most probable value. The findings of the present study represent an advance for surveys intending to incorporate the collection and dosage of placental vitamin A levels into their analyses, thus increasing the arsenal of pre-pathological or subclinical vitamin A deficiency markers, which can allow for earlier intervention on the maternal-infant group. PMID:16638665

  2. Distributed Deliberative Recommender Systems

    NASA Astrophysics Data System (ADS)

    Recio-García, Juan A.; Díaz-Agudo, Belén; González-Sanz, Sergio; Sanchez, Lara Quijano

    Case-Based Reasoning (CBR) is one of most successful applied AI technologies of recent years. Although many CBR systems reason locally on a previous experience base to solve new problems, in this paper we focus on distributed retrieval processes working on a network of collaborating CBR systems. In such systems, each node in a network of CBR agents collaborates, arguments and counterarguments its local results with other nodes to improve the performance of the system's global response. We describe D2ISCO: a framework to design and implement deliberative and collaborative CBR systems that is integrated as a part of jcolibritwo an established framework in the CBR community. We apply D2ISCO to one particular simplified type of CBR systems: recommender systems. We perform a first case study for a collaborative music recommender system and present the results of an experiment of the accuracy of the system results using a fuzzy version of the argumentation system AMAL and a network topology based on a social network. Besides individual recommendation we also discuss how D2ISCO can be used to improve recommendations to groups and we present a second case of study based on the movie recommendation domain with heterogeneous groups according to the group personality composition and a group topology based on a social network.

  3. Data distribution satellite

    NASA Technical Reports Server (NTRS)

    Price, Kent M.; Jorasch, Ronald E.; Wiskerchen, Michael J.

    1991-01-01

    A description is given of a data distribution satellite (DDS) system. The DDS would operate in conjunction with the tracking and data relay satellite system to give ground-based users real time, two-way access to instruments in space and space-gathered data. The scope of work includes the following: (1) user requirements are derived; (2) communication scenarios are synthesized; (3) system design constraints and projected technology availability are identified; (4) DDS communications payload configuration is derived, and the satellite is designed; (5) requirements for earth terminals and network control are given; (6) system costs are estimated, both life cycle costs and user fees; and (7) technology developments are recommended, and a technology development plan is given. The most important results obtained are as follows: (1) a satellite designed for launch in 2007 is feasible and has 10 Gb/s capacity, 5.5 kW power, and 2000 kg mass; (2) DDS features include on-board baseband switching, use of Ku- and Ka-bands, multiple optical intersatellite links; and (3) system user costs are competitive with projected terrestrial communication costs.

  4. Distributed Observer Network

    NASA Technical Reports Server (NTRS)

    2008-01-01

    NASA s advanced visual simulations are essential for analyses associated with life cycle planning, design, training, testing, operations, and evaluation. Kennedy Space Center, in particular, uses simulations for ground services and space exploration planning in an effort to reduce risk and costs while improving safety and performance. However, it has been difficult to circulate and share the results of simulation tools among the field centers, and distance and travel expenses have made timely collaboration even harder. In response, NASA joined with Valador Inc. to develop the Distributed Observer Network (DON), a collaborative environment that leverages game technology to bring 3-D simulations to conventional desktop and laptop computers. DON enables teams of engineers working on design and operations to view and collaborate on 3-D representations of data generated by authoritative tools. DON takes models and telemetry from these sources and, using commercial game engine technology, displays the simulation results in a 3-D visual environment. Multiple widely dispersed users, working individually or in groups, can view and analyze simulation results on desktop and laptop computers in real time.

  5. Distributed Merge Trees

    SciTech Connect

    Morozov, Dmitriy; Weber, Gunther

    2013-01-08

    Improved simulations and sensors are producing datasets whose increasing complexity exhausts our ability to visualize and comprehend them directly. To cope with this problem, we can detect and extract significant features in the data and use them as the basis for subsequent analysis. Topological methods are valuable in this context because they provide robust and general feature definitions. As the growth of serial computational power has stalled, data analysis is becoming increasingly dependent on massively parallel machines. To satisfy the computational demand created by complex datasets, algorithms need to effectively utilize these computer architectures. The main strength of topological methods, their emphasis on global information, turns into an obstacle during parallelization. We present two approaches to alleviate this problem. We develop a distributed representation of the merge tree that avoids computing the global tree on a single processor and lets us parallelize subsequent queries. To account for the increasing number of cores per processor, we develop a new data structure that lets us take advantage of multiple shared-memory cores to parallelize the work on a single node. Finally, we present experiments that illustrate the strengths of our approach as well as help identify future challenges.

  6. Data distribution satellite

    NASA Technical Reports Server (NTRS)

    Stevens, Grady H.

    1992-01-01

    The Data Distribution Satellite (DDS), operating in conjunction with the planned space network, the National Research and Education Network and its commercial derivatives, would play a key role in networking the emerging supercomputing facilities, national archives, academic, industrial, and government institutions. Centrally located over the United States in geostationary orbit, DDS would carry sophisticated on-board switching and make use of advanced antennas to provide an array of special services. Institutions needing continuous high data rate service would be networked together by use of a microwave switching matrix and electronically steered hopping beams. Simultaneously, DDS would use other beams and on board processing to interconnect other institutions with lesser, low rate, intermittent needs. Dedicated links to White Sands and other facilities would enable direct access to space payloads and sensor data. Intersatellite links to a second generation ATDRS, called Advanced Space Data Acquisition and Communications System (ASDACS), would eliminate one satellite hop and enhance controllability of experimental payloads by reducing path delay. Similarly, direct access would be available to the supercomputing facilities and national data archives. Economies with DDS would be derived from its ability to switch high rate facilities amongst users needed. At the same time, having a CONUS view, DDS would interconnect with any institution regardless of how remote. Whether one needed high rate service or low rate service would be immaterial. With the capability to assign resources on demand, DDS will need only carry a portion of the resources needed if dedicated facilities were used. Efficiently switching resources to users as needed, DDS would become a very feasible spacecraft, even though it would tie together the space network, the terrestrial network, remote sites, 1000's of small users, and those few who need very large data links intermittently.

  7. Distributed Observer Network

    NASA Technical Reports Server (NTRS)

    Conroy, Michael; Mazzone, Rebecca; Little, William; Elfrey, Priscilla; Mann, David; Mabie, Kevin; Cuddy, Thomas; Loundermon, Mario; Spiker, Stephen; McArthur, Frank; Srey, Tate; Bonilla, Dennis

    2010-01-01

    The Distributed Observer network (DON) is a NASA-collaborative environment that leverages game technology to bring three-dimensional simulations to conventional desktop and laptop computers in order to allow teams of engineers working on design and operations, either individually or in groups, to view and collaborate on 3D representations of data generated by authoritative tools such as Delmia Envision, Pro/Engineer, or Maya. The DON takes models and telemetry from these sources and, using commercial game engine technology, displays the simulation results in a 3D visual environment. DON has been designed to enhance accessibility and user ability to observe and analyze visual simulations in real time. A variety of NASA mission segment simulations [Synergistic Engineering Environment (SEE) data, NASA Enterprise Visualization Analysis (NEVA) ground processing simulations, the DSS simulation for lunar operations, and the Johnson Space Center (JSC) TRICK tool for guidance, navigation, and control analysis] were experimented with. Desired functionalities, [i.e. Tivo-like functions, the capability to communicate textually or via Voice-over-Internet Protocol (VoIP) among team members, and the ability to write and save notes to be accessed later] were targeted. The resulting DON application was slated for early 2008 release to support simulation use for the Constellation Program and its teams. Those using the DON connect through a client that runs on their PC or Mac. This enables them to observe and analyze the simulation data as their schedule allows, and to review it as frequently as desired. DON team members can move freely within the virtual world. Preset camera points can be established, enabling team members to jump to specific views. This improves opportunities for shared analysis of options, design reviews, tests, operations, training, and evaluations, and improves prospects for verification of requirements, issues, and approaches among dispersed teams.

  8. Distribution of tsunami interevent times

    USGS Publications Warehouse

    Geist, E.L.; Parsons, T.

    2008-01-01

    The distribution of tsunami interevent times is analyzed using global and site-specific (Hilo, Hawaii) tsunami catalogs. An empirical probability density distribution is determined by binning the observed interevent times during a period in which the observation rate is approximately constant. The empirical distributions for both catalogs exhibit non-Poissonian behavior in which there is an abundance of short interevent times compared to an exponential distribution. Two types of statistical distributions are used to model this clustering behavior: (1) long-term clustering described by a universal scaling law, and (2) Omori law decay of aftershocks and triggered sources. The empirical and theoretical distributions all imply an increased hazard rate after a tsunami, followed by a gradual decrease with time approaching a constant hazard rate. Examination of tsunami sources suggests that many of the short interevent times are caused by triggered earthquakes, though the triggered events are not necessarily on the same fault.

  9. Automated Power-Distribution System

    NASA Technical Reports Server (NTRS)

    Thomason, Cindy; Anderson, Paul M.; Martin, James A.

    1990-01-01

    Automated power-distribution system monitors and controls electrical power to modules in network. Handles both 208-V, 20-kHz single-phase alternating current and 120- to 150-V direct current. Power distributed to load modules from power-distribution control units (PDCU's) via subsystem distributors. Ring busses carry power to PDCU's from power source. Needs minimal attention. Detects faults and also protects against them. Potential applications include autonomous land vehicles and automated industrial process systems.

  10. Off-forward parton distribution

    SciTech Connect

    Ji, X.

    1998-12-01

    Recent developments in studying off-forward parton distributions are discussed. In this talk, the author discusses the recent developments in studying the off-forward parton distributions (OFPD`s). He has written a topical review article on the subject, which will soon be published in Journal of Physics G. The interested audience can consult that article for details. His talk consists of three parts: definition of the new distributions, their physical significance, and experimental measurements.

  11. Distribution of Clokey's Eggvetch

    SciTech Connect

    David C. Anderson

    1998-12-01

    monophylla), Utah juniper (Juniperus osteosperma), and big sagebrush (Artemisia tridentata ssp. tridentata). Overall, the populations of Clokey's eggvetch on the NTS appear to be vigorous and do not appear threatened. It is estimated that there are approximately 2300 plants on the NTS. It should be considered as a species of concern because of its localized distribution, but it does not appear to warrant protection under the ESA.

  12. Space platform utilities distribution study

    NASA Technical Reports Server (NTRS)

    Lefever, A. E.

    1980-01-01

    Generic concepts for the installation of power data and thermal fluid distribution lines on large space platforms were discussed. Connections with central utility subsystem modules and pallet interfaces were also considered. Three system concept study platforms were used as basepoints for the detail development. The tradeoff of high voltage low voltage power distribution and the impact of fiber optics as a data distribution mechanism were analyzed. Thermal expansion and temperature control of utility lines and ducts were considered. Technology developments required for implementation of the generic distribution concepts were identified.

  13. Reduplication and Distributivity in Kannada

    ERIC Educational Resources Information Center

    Anderson, Janet Katherine

    2012-01-01

    Reduplication of numerals and pronouns in Kannada is shown to be subject to locality conditions similar to those constraining binding. This dissertation explores an account of distributivity which exploits the similarity to binding, arguing that the source of the distributive reading in Numeral Reduplication is a bound element. [The dissertation…

  14. Algorithm Calculates Cumulative Poisson Distribution

    NASA Technical Reports Server (NTRS)

    Bowerman, Paul N.; Nolty, Robert C.; Scheuer, Ernest M.

    1992-01-01

    Algorithm calculates accurate values of cumulative Poisson distribution under conditions where other algorithms fail because numbers are so small (underflow) or so large (overflow) that computer cannot process them. Factors inserted temporarily to prevent underflow and overflow. Implemented in CUMPOIS computer program described in "Cumulative Poisson Distribution Program" (NPO-17714).

  15. Water Treatment Technology - Distribution Systems.

    ERIC Educational Resources Information Center

    Ross-Harrington, Melinda; Kincaid, G. David

    One of twelve water treatment technology units, this student manual on distribution systems provides instructional materials for six competencies. (The twelve units are designed for a continuing education training course for public water supply operators.) The competencies focus on the following areas: types of pipe for distribution systems, types…

  16. Quality monitored distributed voting system

    DOEpatents

    Skogmo, David

    1997-01-01

    A quality monitoring system can detect certain system faults and fraud attempts in a distributed voting system. The system uses decoy voters to cast predetermined check ballots. Absent check ballots can indicate system faults. Altered check ballots can indicate attempts at counterfeiting votes. The system can also cast check ballots at predetermined times to provide another check on the distributed voting system.

  17. ANN - based distribution system reconfiguration

    SciTech Connect

    Momoh, J.A.; Wang, Yanchun; Rizy, D.T.

    1997-08-01

    This paper describes an Artificial Neural Network (ANN) - based distribution system reconfiguration scheme to reduce system loss. The ANN is trained for different load levels and different network topologies. The proposed scheme has been tested using a 38 - bus distribution system. The results are very promising.

  18. Metric-Free Distributional Comparisons.

    ERIC Educational Resources Information Center

    Haertel, Edward H.; And Others

    Two methods are presented for comparing distributions, such as achievement test score distributions, for distinctly different groups of persons in such a way that the comparison will not be influenced by the particular metric of the test being used. Both methods use percentile scores. One method, attributed to Flanagan, fits a straight line to the…

  19. Current Perspectives in Distributive Education.

    ERIC Educational Resources Information Center

    Klaurens, Mary K., Ed.; Trapnell, Gail, Ed.

    The volume on current perspectives in distributive education contains 29 individually authored articles organized into three sections. The first section on program conceptualization deals with the following subjects: the evolution of distributive education, program planning, advisory committees, placement services, postsecondary distributive…

  20. Informetric Distributions: A Tutorial Review.

    ERIC Educational Resources Information Center

    Rousseau, Ronald; Rousseau, Sandra

    1993-01-01

    Reviews informetric, or bibliometric, distributions, including Lotka's, rank frequency distributions, Zipf functions, Mandelbrot functions, Leimkuhler functions, and Bradford's formulations. An example of the use of these techniques to analyze song texts of Thomas Dolby is given, and results are reported that show a fit with a Leimkuhler function.…

  1. Workload Distribution among Agriculture Teachers

    ERIC Educational Resources Information Center

    Torres, Robert M.; Ulmer, Jonathan D.; Aschenbrener, Mollie S.

    2008-01-01

    Teachers distribute their time in many ways. The study sought to determine how agriculture teachers distribute their time among 11 selected teacher activities (i.e., preparation for instruction; classroom/laboratory teaching; laboratory preparation and/or maintenance; grading/scoring students' work; administrative duties-program management;…

  2. Distributed Interactive Intelligent Tutoring Simulation.

    ERIC Educational Resources Information Center

    Leddo, John; Kolodziej, James

    A Distributed Interactive Intelligent Tutoring Simulation (DIITS) has been developed to train Army Infantry squad and fire team leaders skills to perform military operations cooperatively in urban terrain. It integrates distributed interactive simulation (DIS) and intelligent tutoring systems (ITSs) and thus capitalizes on the strengths of both:…

  3. Flow Distribution in Hydraulic Systems

    NASA Technical Reports Server (NTRS)

    Nguyen, S. N.

    1983-01-01

    General Flow Distribution Program analyzes pressure drops and flow distribution in closed and open hydraulic systems. Analyzes system on basis of incompressible flow though system may contain either compressible or incompressible fluid. Program solves fixed or variable flow problems for series, parallel, or series/parallel systems.

  4. Quality monitored distributed voting system

    DOEpatents

    Skogmo, D.

    1997-03-18

    A quality monitoring system can detect certain system faults and fraud attempts in a distributed voting system. The system uses decoy voters to cast predetermined check ballots. Absent check ballots can indicate system faults. Altered check ballots can indicate attempts at counterfeiting votes. The system can also cast check ballots at predetermined times to provide another check on the distributed voting system. 6 figs.

  5. Distributed Leadership: Friend or Foe?

    ERIC Educational Resources Information Center

    Harris, Alma

    2013-01-01

    Distributed leadership is now widely known and variously enacted in schools and school systems. Distributed leadership implies a fundamental re-conceptualisation of leadership as practice and challenges conventional wisdom about the relationship between formal leadership and organisational performance. There has been much debate, speculation and…

  6. Radial distribution function in polymers

    NASA Astrophysics Data System (ADS)

    Przygocki, Wladyslaw

    1997-02-01

    Radial distribution function is a very useful tool for determination of the polymer structure. The connection between the scattered X-ray intensity and radial distribution function is presented. Some examples of RDF for polyethylene and for poly(ethylene terephtalate).

  7. Leadership in Partially Distributed Teams

    ERIC Educational Resources Information Center

    Plotnick, Linda

    2009-01-01

    Inter-organizational collaboration is becoming more common. When organizations collaborate they often do so in partially distributed teams (PDTs). A PDT is a hybrid team that has at least one collocated subteam and at least two subteams that are geographically distributed and communicate primarily through electronic media. While PDTs share many…

  8. The Future of Distributed Leadership

    ERIC Educational Resources Information Center

    Gronn, Peter

    2008-01-01

    Purpose: This paper aims to assess the empirical utility and conceptual significance of distributed leadership. Design/methodology/approach: Three main sources of evidence are drawn on. The paper reviews some neglected commentary of an early generation of distributed leadership theorists. It also discusses a strand of social science writings on…

  9. COS NUV MAMA Fold Distribution

    NASA Astrophysics Data System (ADS)

    Wheeler, Thomas

    2013-10-01

    The performance of the MAMA microchannel plate can be monitored using a MAMA fold analysis procedure. The fold analysis provides a measurement of the distribution of charge cloud sizes incident upon the anode giving some measure of changes in the pulse-height distribution of the MCP and, therefore, MCP gain. This proposal executes the same steps as Cycle 20 proposal 13128.

  10. 2014 Distributed Wind Market Report

    SciTech Connect

    Orell, A.; Foster, N.

    2015-08-01

    The cover of the 2014 Distributed Wind Market Report.According to the 2014 Distributed Wind Market Report, distributed wind reached a cumulative capacity of almost 1 GW (906 MW) in the United States in 2014, reflecting nearly 74,000 wind turbines deployed across all 50 states, Puerto Rico, and the U.S. Virgin Islands. In total, 63.6 MW of new distributed wind capacity was added in 2014, representing nearly 1,700 units and $170 million in investment across 24 states. In 2014, America's distributed wind energy industry supported a growing domestic industrial base as exports from United States-based small wind turbine manufacturers accounted for nearly 80% of United States-based manufacturers' sales.

  11. Size distribution of ring polymers

    NASA Astrophysics Data System (ADS)

    Medalion, Shlomi; Aghion, Erez; Meirovitch, Hagai; Barkai, Eli; Kessler, David A.

    2016-06-01

    We present an exact solution for the distribution of sample averaged monomer to monomer distance of ring polymers. For non-interacting and local-interaction models these distributions correspond to the distribution of the area under the reflected Bessel bridge and the Bessel excursion respectively, and are shown to be identical in dimension d ≥ 2, albeit with pronounced finite size effects at the critical dimension, d = 2. A symmetry of the problem reveals that dimension d and 4 - d are equivalent, thus the celebrated Airy distribution describing the areal distribution of the d = 1 Brownian excursion describes also a polymer in three dimensions. For a self-avoiding polymer in dimension d we find numerically that the fluctuations of the scaled averaged distance are nearly identical in dimension d = 2, 3 and are well described to a first approximation by the non-interacting excursion model in dimension 5.

  12. Distribution System Voltage Regulation by Distributed Energy Resources

    SciTech Connect

    Ceylan, Oguzhan; Liu, Guodong; Xu, Yan; Tomsovic, Kevin

    2014-01-01

    This paper proposes a control method to regulate voltages in 3 phase unbalanced electrical distribution systems. A constrained optimization problem to minimize voltage deviations and maximize distributed energy resource (DER) active power output is solved by harmony search algorithm. IEEE 13 Bus Distribution Test System was modified to test three different cases: a) only voltage regulator controlled system b) only DER controlled system and c) both voltage regulator and DER controlled system. The simulation results show that systems with both voltage regulators and DER control provide better voltage profile.

  13. Distributed-current-feed and distributed-energy-store railguns

    NASA Astrophysics Data System (ADS)

    Holland, L. D.

    1984-03-01

    In connection with advances in railgun technology evolution toward the development of systems for specific applications, investigations are being conducted regarding a wide variety of power supply and railgun systems. The present study is concerned with the development of the distributed railguns and the introduction of a new type of railgun system specifically designed for applications requiring long accelerators. It is found that the distributed railguns offer a solution to the limits on performance of the breech-fed railguns as the length of the rails becomes large. Attention is given to the pulse-forming network and breech-fed railgun, the breech-fed railgun with parallel pulse-forming network, a distributed-energy-store railgun, a distributed-current-feed (DCF) railgun, and a DCF railgun launcher.

  14. Exploiting replication in distributed systems

    NASA Technical Reports Server (NTRS)

    Birman, Kenneth P.; Joseph, T. A.

    1989-01-01

    Techniques are examined for replicating data and execution in directly distributed systems: systems in which multiple processes interact directly with one another while continuously respecting constraints on their joint behavior. Directly distributed systems are often required to solve difficult problems, ranging from management of replicated data to dynamic reconfiguration in response to failures. It is shown that these problems reduce to more primitive, order-based consistency problems, which can be solved using primitives such as the reliable broadcast protocols. Moreover, given a system that implements reliable broadcast primitives, a flexible set of high-level tools can be provided for building a wide variety of directly distributed application programs.

  15. The alignment-distribution graph

    NASA Technical Reports Server (NTRS)

    Chatterjee, Siddhartha; Gilbert, John R.; Schreiber, Robert

    1993-01-01

    Implementing a data-parallel language such as Fortran 90 on a distributed-memory parallel computer requires distributing aggregate data objects (such as arrays) among the memory modules attached to the processors. The mapping of objects to the machine determines the amount of residual communication needed to bring operands of parallel operations into alignment with each other. We present a program representation called the alignment-distribution graph that makes these communication requirements explicit. We describe the details of the representation, show how to model communication cost in this framework, and outline several algorithms for determining object mappings that approximately minimize residual communication.

  16. The alignment-distribution graph

    NASA Technical Reports Server (NTRS)

    Chatterjee, Siddhartha; Gilbert, John R.; Schreiber, Robert

    1993-01-01

    Implementing a data-parallel language such as Fortran 90 on a distributed-memory parallel computer requires distributing aggregate data objects (such as arrays) among the memory modules attached to the processors. The mapping of objects to the machine determines the amount of residual communication needed to bring operands of parallel operations into alignment with each other. We present a program representation called the alignment distribution graph that makes these communication requirements explicit. We describe the details of the representation, show how to model communication cost in this framework, and outline several algorithms for determining object mappings that approximately minimize residual communication.

  17. Dose distributions in regions containing beta sources: Irregularly shaped source distributions in homogeneous media

    SciTech Connect

    Werner, B.L. )

    1991-11-01

    Methods are introduced by which dose rate distributions due to nonuniform, irregularly shaped distributions of beta emitters can be calculated using dose rate distributions for uniform, spherical source distributions. The dose rate distributions can be written in the MIRD formalism.

  18. Performance of distributed multiscale simulations

    PubMed Central

    Borgdorff, J.; Ben Belgacem, M.; Bona-Casas, C.; Fazendeiro, L.; Groen, D.; Hoenen, O.; Mizeranschi, A.; Suter, J. L.; Coster, D.; Coveney, P. V.; Dubitzky, W.; Hoekstra, A. G.; Strand, P.; Chopard, B.

    2014-01-01

    Multiscale simulations model phenomena across natural scales using monolithic or component-based code, running on local or distributed resources. In this work, we investigate the performance of distributed multiscale computing of component-based models, guided by six multiscale applications with different characteristics and from several disciplines. Three modes of distributed multiscale computing are identified: supplementing local dependencies with large-scale resources, load distribution over multiple resources, and load balancing of small- and large-scale resources. We find that the first mode has the apparent benefit of increasing simulation speed, and the second mode can increase simulation speed if local resources are limited. Depending on resource reservation and model coupling topology, the third mode may result in a reduction of resource consumption. PMID:24982258

  19. Visualizing Spatially Varying Distribution Data

    NASA Technical Reports Server (NTRS)

    Kao, David; Luo, Alison; Dungan, Jennifer L.; Pang, Alex; Biegel, Bryan A. (Technical Monitor)

    2002-01-01

    Box plot is a compact representation that encodes the minimum, maximum, mean, median, and quarters information of a distribution. In practice, a single box plot is drawn for each variable of interest. With the advent of more accessible computing power, we are now facing the problem of visual icing data where there is a distribution at each 2D spatial location. Simply extending the box plot technique to distributions over 2D domain is not straightforward. One challenge is reducing the visual clutter if a box plot is drawn over each grid location in the 2D domain. This paper presents and discusses two general approaches, using parametric statistics and shape descriptors, to present 2D distribution data sets. Both approaches provide additional insights compared to the traditional box plot technique

  20. Multiple complementary gas distribution assemblies

    DOEpatents

    Ng, Tuoh-Bin; Melnik, Yuriy; Pang, Lily L; Tuncel, Eda; Nguyen, Son T; Chen, Lu

    2016-04-05

    In one embodiment, an apparatus includes a first gas distribution assembly that includes a first gas passage for introducing a first process gas into a second gas passage that introduces the first process gas into a processing chamber and a second gas distribution assembly that includes a third gas passage for introducing a second process gas into a fourth gas passage that introduces the second process gas into the processing chamber. The first and second gas distribution assemblies are each adapted to be coupled to at least one chamber wall of the processing chamber. The first gas passage is shaped as a first ring positioned within the processing chamber above the second gas passage that is shaped as a second ring positioned within the processing chamber. The gas distribution assemblies may be designed to have complementary characteristic radial film growth rate profiles.

  1. The Binomial Distribution in Shooting

    ERIC Educational Resources Information Center

    Chalikias, Miltiadis S.

    2009-01-01

    The binomial distribution is used to predict the winner of the 49th International Shooting Sport Federation World Championship in double trap shooting held in 2006 in Zagreb, Croatia. The outcome of the competition was definitely unexpected.

  2. 2013 Distributed Wind Market Report

    SciTech Connect

    Orrell, Alice C.; Rhoads-Weaver, H. E.; Flowers, Larry T.; Gagne, Matthew N.; Pro, Boyd H.; Foster, Nikolas AF

    2014-08-20

    The purpose of this report is to quantify and summarize the 2013 U.S. distributed wind market to help plan and guide future investments and decisions by industry stakeholders, utilities, state and federal agencies, and other interested parties.

  3. BESIII production with distributed computing

    NASA Astrophysics Data System (ADS)

    Zhang, X. M.; Yan, T.; Zhao, X. H.; Ma, Z. T.; Yan, X. F.; Lin, T.; Deng, Z. Y.; Li, W. D.; Belov, S.; Pelevanyuk, I.; Zhemchugov, A.; Cai, H.

    2015-12-01

    Distributed computing is necessary nowadays for high energy physics experiments to organize heterogeneous computing resources all over the world to process enormous amounts of data. The BESIII experiment in China, has established its own distributed computing system, based on DIRAC, as a supplement to local clusters, collecting cluster, grid, desktop and cloud resources from collaborating member institutes around the world. The system consists of workload management and data management to deal with the BESIII Monte Carlo production workflow in a distributed environment. A dataset-based data transfer system has been developed to support data movements among sites. File and metadata management tools and a job submission frontend have been developed to provide a virtual layer for BESIII physicists to use distributed resources. Moreover, the paper shows the experience to cope with lack of grid experience and low manpower among the BESIII community.

  4. Distributed teaming on JPL projects

    NASA Technical Reports Server (NTRS)

    Baroff, L. E.

    2002-01-01

    This paper addresses structures, actions and technologies that contribute to real team development of a distributed team, and the leadership skills and tools that are used to implement that team development.

  5. Reactive Power from Distributed Energy

    SciTech Connect

    Kueck, John; Kirby, Brendan; Rizy, Tom; Li, Fangxing; Fall, Ndeye

    2006-12-15

    Distributed energy is an attractive option for solving reactive power and distribution system voltage problems because of its proximity to load. But the cost of retrofitting DE devices to absorb or produce reactive power needs to be reduced. There also needs to be a market mechanism in place for ISOs, RTOs, and transmission operators to procure reactive power from the customer side of the meter where DE usually resides. (author)

  6. Generalized parton distributions in nuclei

    SciTech Connect

    Vadim Guzey

    2009-12-01

    Generalized parton distributions (GPDs) of nuclei describe the distribution of quarks and gluons in nuclei probed in hard exclusive reactions, such as e.g. deeply virtual Compton scattering (DVCS). Nuclear GPDs and nuclear DVCS allow us to study new aspects of many traditional nuclear effects (nuclear shadowing, EMC effect, medium modifications of the bound nucleons) as well as to access novel nuclear effects. In my talk, I review recent theoretical progress in the area of nuclear GPDs.

  7. Distributed processing for speech understanding

    SciTech Connect

    Bronson, E.C.; Siegel, L.

    1983-01-01

    Continuous speech understanding is a highly complex artificial intelligence task requiring extensive computation. This complexity precludes real-time speech understanding on a conventional serial computer. Distributed processing technique can be applied to the speech understanding task to improve processing speed. In the paper, the speech understanding task and several speech understanding systems are described. Parallel processing techniques are presented and a distributed processing architecture for speech understanding is outlined. 35 references.

  8. Structure functions and parton distributions

    SciTech Connect

    Martin, A.D.; Stirling, W.J.; Roberts, R.G.

    1995-07-01

    The MRS parton distribution analysis is described. The latest sets are shown to give an excellent description of a wide range of deep-inelastic and other hard scattering data. Two important theoretical issues-the behavior of the distributions at small x and the flavor structure of the quark sea-are discussed in detail. A comparison with the new structure function data from HERA is made, and the outlook for the future is discussed.

  9. Modeling Nucleon Generalized Parton Distributions

    SciTech Connect

    Radyushkin, Anatoly V.

    2013-05-01

    We discuss building models for nucleon generalized parton distributions (GPDs) H and E that are based on the formalism of double distributions (DDs). We find that the usual "DD+D-term'' construction should be amended by an extra term, generated by GPD E(x,\\xi). Unlike the $D$-term, this function has support in the whole -1 < x< 1 region, and in general does not vanish at the border points|x|=\\xi.

  10. COS NUV MAMA Fold Distribution

    NASA Astrophysics Data System (ADS)

    Wheeler, Thomas

    2010-09-01

    The performance of the MAMA microchannel plate can be monitored using a MAMA fold analysis procedure. The fold analysis provides a measurement of the distribution of charge cloud sizes incident upon the anode giving some measure of changes in the pulse-height distribution of the MCP and, therefore, MCP gain. This proposal executes the same steps as the COS MAMA Fold Analysis {11891} during Cycle 17.

  11. COS NUV MAMA Fold Distribution

    NASA Astrophysics Data System (ADS)

    Wheeler, Thomas

    2012-10-01

    The performance of the MAMA microchannel plate can be monitored using a MAMA fold analysis procedure. The fold analysis provides a measurement of the distribution of charge cloud sizes incident upon the anode giving some measure of changes in the pulse-height distribution of the MCP and, therefore, MCP gain. This proposal executes the same steps as the COS MAMA Fold Analysis {12723} during Cycle 19.

  12. Power Spectrum of Atmospheric Scintillation for the Deep Space Network Goldstone Ka-Band Downlink

    NASA Technical Reports Server (NTRS)

    Ho, C.; Wheelon, A.

    2004-01-01

    Dynamic signal fluctuations due to atmospheric scintillations may impair the Ka-band (around 32-GHz) link sensitivities for a low-margin Deep Space Network (DSN) receiving system. The ranges of frequency and power of the fast fluctuating signals (time scale less than 1 min) are theoretically investigated using the spatial covariance and turbulence theory. Scintillation power spectrum solutions are derived for both a point receiver and a finite-aperture receiver. The aperture-smoothing frequency ((omega(sub s)), corner frequency ((omega(sub c)), and damping rate are introduced to define the shape of the spectrum for a finite-aperture antenna. The emphasis is put on quantitatively describing the aperture-smoothing effects and graphically estimating the corner frequency for a large aperture receiver. Power spectral shapes are analyzed parametrically in detail through both low- and high-frequency approximations. It is found that aperture-averaging effects become significant when the transverse correlation length of the scintillation is smaller than the antenna radius. The upper frequency or corner frequency for a finite-aperture receiver is controlled by both the Fresnel frequency and aperture-smoothing frequency. Above the aperture-smoothing frequency, the spectrum rolls off at a much faster rate of exp (-omega(sup 2)/omega(sup 2, sub s), rather than omega(sup -8/3), which is customary for a point receiver. However, a relatively higher receiver noise level can mask the fast falling-off shape and make it hard to be identified. We also predict that when the effective antenna radius a(sub r) less than or = 6 m, the corner frequency of its power spectrum becomes the same as that for a point receiver. The aperture-smoothing effects are not obvious. We have applied these solutions to the scenario of a DSN Goldstone 34-m-diameter antenna and predicted the power spectrum shape for the receiving station. The maximum corner frequency for the receiver (with omega(sub s) = 0.79 omega(sub 0) is found to be 0.44 Hz (or 1.0 omega(sub 0), while the fading rate (or fading slope) is about 0.06 dB/s.

  13. Telemetry down-link Doppler as an attitude sensor for spin stabilized spacecraft

    NASA Technical Reports Server (NTRS)

    Hendry, S. D.

    1995-01-01

    The communications antenna on a spin stabilized spacecraft is seldom located on the spin axis, hence, the antenna is in motion relative to the center of mass of the spacecraft. The Doppler shift observed at the ground or space relay communications receivers will include oscillations whose frequency and amplitude are functions of the motion of the antenna and the attitude of the spacecraft relative to the line of sight (LOS). This functional dependence creates the possibility of estimating attitude parameters from Doppler measurements. This paper presents mathematical models of Doppler oscillations from spinning spacecraft, including the effects of nutation. Algorithms for estimating spin rate, attitude and nutation angle are described. Results of analysis of Doppler tracking of GOES-8 and WIND are also discussed.

  14. Deep-Space Optical Communications Downlink Budget from Mars: System Parameters

    NASA Astrophysics Data System (ADS)

    Biswas, A.; Piazzolla, S.

    2003-08-01

    This article describes the elements of a design control table for an optical communications link from a spacecraft in Mars orbit to a ground-based receiving station on Earth. A fixed average laser transmitter power of 5W transmitted through a 30-cm-diameter near-diffraction-limited telescope is assumed, along with a 10-m-diameter ground receiving antenna. Pulse-position modulation of the laser with direct detection also is assumed. An end-to-end systems analysis is presented to provide the expected signal and background-noise photons as a function of the Earth-Mars range. The signal and noise photons received are treated using an ideal Poisson channel model in order to predict data rates when Mars is close to conjunction. The data rates range from 5 to 40 Mb/s with a large part of the uncertainty owing its origin to variability of the atmosphere. The article also concludes that further work is required in order to narrow the rather wide range of preliminary data rates presented.

  15. Uplink-Downlink: A History of the Deep Space Network, 1957-1997

    NASA Technical Reports Server (NTRS)

    Mudgway, Douglas J.; Launius, Roger (Technical Monitor)

    2001-01-01

    In these pages, the informed reader will discover a simple description of what the Deep Space Network (DSN) is about, and how it works an aspect of NASA's spectacular planetary program that seldom found its way into the popular media coverage of those major events. Future historical researchers will find a complete record of the origin and birth of the DSN, its subsequent development and expansion over the ensuing four decades, and a description of the way in which the DSN was used to fulfill the purpose for which it was created. At the same time, the specialist reader is provided with an abundant source of technical references that address every aspect of the advanced telecommunications technology on which the success of the DSN depended. And finally, archivists, educators, outreach managers, and article writers will have ready recourse to the inner workings of the DSN and how they related to the more publicly visible events of the planetary space program.

  16. Interference effects on Space Station Freedom and space shuttle orbiter Ku-band downlinks

    NASA Technical Reports Server (NTRS)

    Kwon, Hyuck M.; Loh, Yin-Chung; Tu, Kwei

    1993-01-01

    The space shuttle orbiter (SSO) and Ku-band single access return (KSAR) link and the Space Station Freedom (SSF) KSAR link via the tracking and data relay satellite system (TDRSS) use the same carrier frequency. The interference between spacecraft is minimized by opposite antenna polarizations and by TDRSS antenna beam pointing, but if the SSF and SSO are in close proximity, it is expected that mutual interference will be significant. Recently, Tsang and Su (1988, 1989) simulated the mutual interference effects, using a practical nonlinear bandlimited channel. The purpose of this paper is to demonstrate that a simplified (i.e., linear band-limited channel) analytical approach will yield adequate accuracy for the expected range of operating conditions. Relative degradation in bit energy-to-thermal noise power spectral density ratio to achieve a 10 exp -5 coded bit-error-probability is determined to be 4 dB for the Ku-band SSO-to-TDRS I-channel return link with a 4.5 dB effective signal-to-interference total power ratio (S/I) when the Ku-band SSF-to-TDRS return link interferes, whereas Su's simulation yields approximately 5 dB degradation. For the Ku-band SSF-to-TDRS return link, both analysis and simulation results yield a relative signal degradation of 0.4 dB at the effective S/I = 21.6 dB. In conclusion, interference on the Ku-band SSO-to-TDRS I-channel return link is significant, but on the Ku-band SSF-to-TDRS return link it is negligible.

  17. Digital TV tri-state delta modulation system for Space Shuttle ku-band downlink

    NASA Technical Reports Server (NTRS)

    Udalov, S.; Huth, G. K.; Roberts, D.; Batson, B. H.

    1982-01-01

    A tri-state delta modulation/demodulation (TSDM) technique which provides for efficient run-length coding of constant-intensity segments of a TV picture is described. Aspects of the hardware implementation of a high-speed TSDM transmitter and receiver for black-and-white TV or field-sequential color or NTSC format color are reviewed. Run-length encoding of the TSDM output can consistently reduce the required channel data rate well below one bit per sample. As compared with a bistate delta modulation system, the present technique eliminates granularity in the reconstructed video without degrading rise or fall times. About 40 chips are used by TSDM when used to handle the luminance information in a color link. A possible overall space and ground functional configuration to accommodate Shuttle digital TV with scrambling for privacy is presented.

  18. Massive MIMO-OFDM indoor visible light communication system downlink architecture design

    NASA Astrophysics Data System (ADS)

    Lang, Tian; Li, Zening; Chen, Gang

    2014-10-01

    Multiple-input multiple-output (MIMO) technique is now used in most new broadband communication system, and orthogonal frequency division multiplexing (OFDM) is also utilized within current 4th generation (4G) of mobile telecommunication technology. With MIMO and OFDM combined, visible light communication (VLC) system's diversity gain is increase, yet system capacity for dispersive channels is also enhanced. Moreover, with the emerging massive MIMO-OFDM VLC system, there are significant advantages than smaller systems' such as channel hardening, further increasing of energy efficiency (EE) and spectral efficiency (SE) based on law of large number. This paper addresses one of the major technological challenges, system architecture design, which was solved by semispherical beehive structure (SBS) receiver and so that diversity gain can be identified and applied in Massive MIMO VLC system. Simulation results shows that the proposed design clearly presents a spatial diversity over conventional VLC systems.

  19. Simultaneous S- and X-band uplink-downlink performance at DSS 13

    NASA Technical Reports Server (NTRS)

    Freiley, A. J.

    1988-01-01

    The Deep Space Station 13 26-meter antenna with the second generation S/X feedcone was tested to determine the dual S- and X-band (2.1 to 2.3 GHz and 7.1 to 8.5 GHz) transmit and receive performance. Measurements were conducted using the 20 kW transmitters at S- and X-band while simultaneously receiving S- and X-band. This system proved to be very quiet compared with the other DSN antennas. Under normal tracking configurations, no noise burst or intermodulation product (IMP) activity was detectable to the -175 dBm level. To prove the instrumentation's ability to detect such phenomena, an IMP generator was introduced onto the system with positive, verifiable results. The IMP occurred at the -162 dBm level, accompanied by moderate noise burst activity, and was readily repeatable. The measurement also showed the possible need for additional fourth channel filtering in the system to reduce the effect of the transmitter power on the low noise amplifiers.

  20. Real Time Data/Video/Voice Uplink and Downlink for Kuiper Airborne Observatory

    NASA Technical Reports Server (NTRS)

    Harper, Doyal A.

    1997-01-01

    LFS was an educational outreach adventure which brought the excitement of astronomical exploration on NASA's Kuiper Airborne Observatory (KAO) to a nationwide audience of children, parents and children through live, interactive television, broadcast from the KAO at an altitude of 41,000 feet during an actual scientific observing mission. The project encompassed three KAO flights during the fall of 1995, including a short practice mission, a daytime observing flight between Moffett Field, California to Houston, Texas, and a nighttime mission from Houston back to Moffett Field. The University of Chicago infrared research team participated in planning the program, developing auxiliary materials including background information and lesson plans, developing software which allowed students on the ground to control the telescope and on-board cameras via the Internet from the Adler Planetarium in Chicago, and acting as on-camera correspondents to explain and answer questions about the scientific research conducted during the flights.

  1. Experimental verification of fiber-coupling efficiency for satellite-to-ground atmospheric laser downlinks.

    PubMed

    Takenaka, Hideki; Toyoshima, Morio; Takayama, Yoshihisa

    2012-07-01

    Optical communication is a high-capacity method that can handle considerable satellite data. When common-fiber optical devices such as optical fiber amplifiers based on single mode fibers are used in free-space laser communication systems, the laser beam has to be coupled to a single-mode fiber. Under atmospheric turbulence it would be difficult to make the required fiber coupling efficiency in satellite-to-ground laser propagation paths. A fast-steering mirror that can operate at high frequencies under atmospheric turbulence is fabricated, and its tracking performance is verified in real satellite-to-ground laser communication experiments. The measured fiber coupling loss of 10-19 dB in satellite-to-ground laser communication links under atmospheric turbulence shows good agreement with the predicted fiber coupling efficiency of 17 dB.

  2. Distribution functions of probabilistic automata

    NASA Technical Reports Server (NTRS)

    Vatan, F.

    2001-01-01

    Each probabilistic automaton M over an alphabet A defines a probability measure Prob sub(M) on the set of all finite and infinite words over A. We can identify a k letter alphabet A with the set {0, 1,..., k-1}, and, hence, we can consider every finite or infinite word w over A as a radix k expansion of a real number X(w) in the interval [0, 1]. This makes X(w) a random variable and the distribution function of M is defined as usual: F(x) := Prob sub(M) { w: X(w) < x }. Utilizing the fixed-point semantics (denotational semantics), extended to probabilistic computations, we investigate the distribution functions of probabilistic automata in detail. Automata with continuous distribution functions are characterized. By a new, and much more easier method, it is shown that the distribution function F(x) is an analytic function if it is a polynomial. Finally, answering a question posed by D. Knuth and A. Yao, we show that a polynomial distribution function F(x) on [0, 1] can be generated by a prob abilistic automaton iff all the roots of F'(x) = 0 in this interval, if any, are rational numbers. For this, we define two dynamical systems on the set of polynomial distributions and study attracting fixed points of random composition of these two systems.

  3. Double distributions and evolution equations

    SciTech Connect

    A.V. Radyushkin

    1998-05-01

    Applications of perturbative QCD to deeply virtual Compton scattering and hard exclusive meson electroproduction processes require a generalization of usual parton distributions for the case when long-distance information is accumulated in nonforward matrix elements < p{prime} {vert_bar}O(0,z){vert_bar}p > of quark and gluon light-cone operators. In their previous papers the authors used two types of nonperturbative functions parameterizing such matrix elements: double distributions F(x,y;t) and nonforward distribution functions F{sub {zeta}}(X;t). Here they discuss in more detail the double distributions (DD's) and evolution equations which they satisfy. They propose simple models for F(x,y;t=0) DD's with correct spectral and symmetry properties which also satisfy the reduction relations connecting them to the usual parton densities f(x). In this way, they obtain self-consistent models for the {zeta}-dependence of nonforward distributions. They show that, for small {zeta}, one can easily obtain nonforward distributions (in the X > {zeta} region) from the parton densities: F{sub {zeta}} (X;t=0) {approx} f(X{minus}{zeta}/2).

  4. Modeled ground water age distributions

    USGS Publications Warehouse

    Woolfenden, Linda R.; Ginn, Timothy R.

    2009-01-01

    The age of ground water in any given sample is a distributed quantity representing distributed provenance (in space and time) of the water. Conventional analysis of tracers such as unstable isotopes or anthropogenic chemical species gives discrete or binary measures of the presence of water of a given age. Modeled ground water age distributions provide a continuous measure of contributions from different recharge sources to aquifers. A numerical solution of the ground water age equation of Ginn (1999) was tested both on a hypothetical simplified one-dimensional flow system and under real world conditions. Results from these simulations yield the first continuous distributions of ground water age using this model. Complete age distributions as a function of one and two space dimensions were obtained from both numerical experiments. Simulations in the test problem produced mean ages that were consistent with the expected value at the end of the model domain for all dispersivity values tested, although the mean ages for the two highest dispersivity values deviated slightly from the expected value. Mean ages in the dispersionless case also were consistent with the expected mean ages throughout the physical model domain. Simulations under real world conditions for three dispersivity values resulted in decreasing mean age with increasing dispersivity. This likely is a consequence of an edge effect. However, simulations for all three dispersivity values tested were mass balanced and stable demonstrating that the solution of the ground water age equation can provide estimates of water mass density distributions over age under real world conditions.

  5. Distribution System of the Future

    SciTech Connect

    Kueck, JD

    2003-04-23

    The distribution system of the future is going to be as much of a revolution to the electric energy industry as the wireless telephone has been to consumer communications. An electricity market transformation must occur before the changes can take place, but this evolution is already starting to occur in many parts of the country. In this paper, we discuss a vision for a future distribution system, areas that will be key for technology development, and the advantages of the new electricity market. Present day distribution systems are in a sense, unintelligent. Distribution systems respond to faults, or short circuits, by sensing the very high fault current and then opening circuit breakers to isolate the fault. Some newer automated systems determine fault location and then close other circuit breakers to provide an alternate path for power after the fault so that the number of customers left without power is minimized, but the extent of the reconfiguration is limited. Distribution systems also have some methods to regulate voltage, but there is little real time local response to contingencies such as loss of a transmission line or a generator. In present day distribution systems, there is very little control of load, or demand response, and Distributed Energy Resources (DER, distributed generation, storage, and responsive load) located in the distribution system are prohibited from even regulating voltage. In fact, industry standards and utility interconnection agreements typically require that when a contingency occurs on a distribution or transmission system that results in a voltage or frequency excursion, the DER is to disconnect rather than help. There is a pressing need to evolve the distribution system model to one that can respond to contingencies sensed locally, and has the local intelligence and autonomy to deal with contingencies such as unusual loading, transmission congestion, and line outages. Markets must be simple for customers to participate in the

  6. SCDM in a Distributed Environment

    NASA Technical Reports Server (NTRS)

    Crowley, Sandra L.; Housch, Helen I.; Madison, Heather L.

    2004-01-01

    The Software Configuration Management (SCM) of the Space Launch Initiative (SLI) Advanced Engineering Environment (AEE) products is performed in a distributed environment-meaning the activities performed during the project lifecycle are across numerous NASA Centers, facilities, organizations, colleges and industry. SCM is the glue that holds the project and products together-especially in a distributed environment. It identifies, controls, accounts, and verified the details of the products; the schedule of activities; the assigned responsibilities; and the required resources, including staff, tools, and computer facilities. Data/document management (DM) captures and conveys the SCM and project efforts. SCM and DM are integrally linked; hence, Software Configuration and Data Management (SCDM). This paper discusses one team's challenges in implementing SCDM in a distributed environment. The distributed nature of the project introduces new opportunities for moving SCDM to the next level of usefulness in today's high-tech development arena. The lessons learned from the implementation of distributed SCDM in support of the SLI AEE Project provide valuable information for future implementations of SCM and DM.

  7. Knowledge in a distributed environment

    SciTech Connect

    Moses, Y.O.

    1986-01-01

    The distributed nature of information in a distributed system is one of the major issues that protocols for cooperation and coordination between individual components in such a system must handle. Individual sites customarily have only partial knowledge about the general state of the system. Moreover, different information is available at the different sites of the system. Consequently, a central role of communication in such protocols is to inform particular sites about events that take place at other sites, and to transform the system's state of knowledge in a way that will guarantee the successful achievement of the goals of the protocol. This thesis is an initial attempt to study the role of knowledge in distributed system. A general framework is presented for defining knowledge in a distributed system, and a variety of states of knowledge are identified that groups of processors may have. These states of knowledge seem to capture basic aspects of coordinated actions in a distributed environment. This machinery is applied to the analysis of a number of problems. Finally, this machinery is applied to the study of fault tolerance in systems of unreliable processors, providing considerable insight into the Byzantine agreement problem, and obtaining improved protocols for Byzantine agreement and many related problems.

  8. Distributed Wind Policy Comparison Tool

    SciTech Connect

    2011-12-01

    Power through Policy: 'Best Practices' for Cost-Effective Distributed Wind is a U.S. Department of Energy (DOE)-funded project to identify distributed wind technology policy best practices and to help policymakers, utilities, advocates, and consumers examine their effectiveness using a pro forma model. Incorporating a customized feed from the Database of State Incentives for Renewables and Efficiency (DSIRE), the Web-based Distributed Wind Policy Comparison Tool (Policy Tool) is designed to assist state, local, and utility officials in understanding the financial impacts of different policy options to help reduce the cost of distributed wind technologies. The Policy Tool can be used to evaluate the ways that a variety of federal and state policies and incentives impact the economics of distributed wind (and subsequently its expected market growth). It also allows policymakers to determine the impact of policy options, addressing market challenges identified in the U.S. DOE’s '20% Wind Energy by 2030' report and helping to meet COE targets.

  9. Size distribution of ring polymers

    PubMed Central

    Medalion, Shlomi; Aghion, Erez; Meirovitch, Hagai; Barkai, Eli; Kessler, David A.

    2016-01-01

    We present an exact solution for the distribution of sample averaged monomer to monomer distance of ring polymers. For non-interacting and local-interaction models these distributions correspond to the distribution of the area under the reflected Bessel bridge and the Bessel excursion respectively, and are shown to be identical in dimension d ≥ 2, albeit with pronounced finite size effects at the critical dimension, d = 2. A symmetry of the problem reveals that dimension d and 4 − d are equivalent, thus the celebrated Airy distribution describing the areal distribution of the d = 1 Brownian excursion describes also a polymer in three dimensions. For a self-avoiding polymer in dimension d we find numerically that the fluctuations of the scaled averaged distance are nearly identical in dimension d = 2, 3 and are well described to a first approximation by the non-interacting excursion model in dimension 5. PMID:27302596

  10. Distributed resource management: garbage collection

    SciTech Connect

    Bagherzadeh, N.

    1987-01-01

    In recent years, there has been a great interest in designing high-performance distributed symbolic-processing computers. These architectures have special needs for resource management and dynamic reclamation of unused memory cells and objects. The memory management or garbage-collection aspects of these architectures are studied. Also introduced is a synchronous distributed algorithm for garbage collection. A special data structure is defined to handle the distributed nature of the problem. The author formally expresses the algorithm and shows the results of a synchronous garbage-collection simulation and its effect on the interconnection-network message to traffic. He presents an asynchronous distributed garbage collection to handle the resource management for a system that does not require a global synchronization mechanism. The distributed data structure is modified to include the asynchronous aspects of the algorithm. This method is extended to a multiple-mutator scheme, and the problem of having several processors share portion of a cyclical graph is discussed. Two models for the analytical study of the garbage-collection algorithms discussed are provided.

  11. Phenomenology of preequilibrium angular distributions

    SciTech Connect

    Kalbach, C.; Mann, F.M.

    1980-05-01

    The systematics of continuum angular distributions from a wide variety of light ion nuclear reactions have been studied. To first order, the shape of the angular distributions have been found to depend only on the energy of the outgoing particle and on the division of the cross section into multi-step direct and multi-step compound parts. The angular distributions can be described in terms of Legendre polynomials with the reduced polynomial coefficients exhibiting a simple dependence on the outgoing particle energy. Two integer and four continuous parameters with universal values are needed to describe the coefficients for outgoing energies of 2 to 60 MeV in all the reaction types studied. This parameterization combined with a modified Griffin model computer code permits the calculation of double differential cross sections for light ion continuum reactions where no data is available.

  12. Overdispersion: Notes on discrete distributions

    SciTech Connect

    Bowman, K.O. ); Shenton, L.R. ); Kastenbaum, M.A. ); Broman, K. )

    1992-09-01

    We introduce mixtures of binomial distributions derived by assuming that the probability parameter p varies according to some law. We use the transformation p = exp([minus]t) and consider various appropriate densities for the transformed variables. In the process, the Laplace transform becomes the fundamental entity. Large numbers of new binomial mixtures are generated in this way. Some transformations may involve several variates that lead to multivariate'' binomial mixtures. An extension of this to the logarithmic distribution, with parameter p, is possible. Frullani integrals and Laplace transforms are encountered. Graphical representations of some of the more significant distributions are given. These include probability functions, regions of validity, and three dimensional representations of probability functions showing the response to variation of parameters when two parameters are involved.

  13. Overdispersion: Notes on discrete distributions

    SciTech Connect

    Bowman, K.O.; Shenton, L.R.; Kastenbaum, M.A.; Broman, K.

    1992-09-01

    We introduce mixtures of binomial distributions derived by assuming that the probability parameter p varies according to some law. We use the transformation p = exp({minus}t) and consider various appropriate densities for the transformed variables. In the process, the Laplace transform becomes the fundamental entity. Large numbers of new binomial mixtures are generated in this way. Some transformations may involve several variates that lead to ``multivariate`` binomial mixtures. An extension of this to the logarithmic distribution, with parameter p, is possible. Frullani integrals and Laplace transforms are encountered. Graphical representations of some of the more significant distributions are given. These include probability functions, regions of validity, and three dimensional representations of probability functions showing the response to variation of parameters when two parameters are involved.

  14. Distribution Workshop 3. Final report

    SciTech Connect

    Sullivan, S.

    1991-12-01

    Over 40 utilities participated in Distribution Workshop III sponsored by the Gas Research Institute's Municipal Gas System Advisory Committee (MGSAC) and held in New Orleans, November 30-December 1, 1990. The primary objective of DWIII was to assist GRI in determining the major needs and concerns the gas distribution industry is currently facing or anticipating in the future. Eight topical areas created the basic structure for the focus group sessions: New equipment decisions; the emergency situation; dealing with leaks; communications in the Information Age; technology transfer; main and service extension; repair, renovation, and maintenance; and customer service. Both topic-specific needs, and more general, cross-cutting 'macro' themes representing social, industry, technology, and process issues, were identified as challenges facing the industry. Two additional groups, comprised of GRI staff and GRI's Distribution Project Advisor Group (DPAG), were assembled to examine the findings in order to generate and prioritize potential research ideas.

  15. Maintaining consistency in distributed systems

    NASA Technical Reports Server (NTRS)

    Birman, Kenneth P.

    1991-01-01

    In systems designed as assemblies of independently developed components, concurrent access to data or data structures normally arises within individual programs, and is controlled using mutual exclusion constructs, such as semaphores and monitors. Where data is persistent and/or sets of operation are related to one another, transactions or linearizability may be more appropriate. Systems that incorporate cooperative styles of distributed execution often replicate or distribute data within groups of components. In these cases, group oriented consistency properties must be maintained, and tools based on the virtual synchrony execution model greatly simplify the task confronting an application developer. All three styles of distributed computing are likely to be seen in future systems - often, within the same application. This leads us to propose an integrated approach that permits applications that use virtual synchrony with concurrent objects that respect a linearizability constraint, and vice versa. Transactional subsystems are treated as a special case of linearizability.

  16. Integrated Transmission and Distribution Control

    SciTech Connect

    Kalsi, Karanjit; Fuller, Jason C.; Tuffner, Francis K.; Lian, Jianming; Zhang, Wei; Marinovici, Laurentiu D.; Fisher, Andrew R.; Chassin, Forrest S.; Hauer, Matthew L.

    2013-01-16

    Distributed, generation, demand response, distributed storage, smart appliances, electric vehicles and renewable energy resources are expected to play a key part in the transformation of the American power system. Control, coordination and compensation of these smart grid assets are inherently interlinked. Advanced control strategies to warrant large-scale penetration of distributed smart grid assets do not currently exist. While many of the smart grid technologies proposed involve assets being deployed at the distribution level, most of the significant benefits accrue at the transmission level. The development of advanced smart grid simulation tools, such as GridLAB-D, has led to a dramatic improvement in the models of smart grid assets available for design and evaluation of smart grid technology. However, one of the main challenges to quantifying the benefits of smart grid assets at the transmission level is the lack of tools and framework for integrating transmission and distribution technologies into a single simulation environment. Furthermore, given the size and complexity of the distribution system, it is crucial to be able to represent the behavior of distributed smart grid assets using reduced-order controllable models and to analyze their impacts on the bulk power system in terms of stability and reliability. The objectives of the project were to: • Develop a simulation environment for integrating transmission and distribution control, • Construct reduced-order controllable models for smart grid assets at the distribution level, • Design and validate closed-loop control strategies for distributed smart grid assets, and • Demonstrate impact of integrating thousands of smart grid assets under closed-loop control demand response strategies on the transmission system. More specifically, GridLAB-D, a distribution system tool, and PowerWorld, a transmission planning tool, are integrated into a single simulation environment. The integrated environment

  17. Kinetic narrowing of size distribution

    NASA Astrophysics Data System (ADS)

    Dubrovskii, V. G.

    2016-05-01

    We present a model that reveals an interesting possibility for narrowing the size distribution of nanostructures when the deterministic growth rate changes its sign from positive to negative at a certain stationary size. Such a behavior occurs in self-catalyzed one-dimensional III-V nanowires and more generally whenever a negative "adsorption-desorption" term in the growth rate is compensated by a positive "diffusion flux." By asymptotically solving the Fokker-Planck equation, we derive an explicit representation for the size distribution that describes either Poissonian broadening or self-regulated narrowing depending on the parameters. We show how the fluctuation-induced spreading of the size distribution can be completely suppressed in systems with size self-stabilization. These results can be used for obtaining size-uniform ensembles of different nanostructures.

  18. Distributed systems status and control

    NASA Technical Reports Server (NTRS)

    Kreidler, David; Vickers, David

    1990-01-01

    Concepts are investigated for an automated status and control system for a distributed processing environment. System characteristics, data requirements for health assessment, data acquisition methods, system diagnosis methods and control methods were investigated in an attempt to determine the high-level requirements for a system which can be used to assess the health of a distributed processing system and implement control procedures to maintain an accepted level of health for the system. A potential concept for automated status and control includes the use of expert system techniques to assess the health of the system, detect and diagnose faults, and initiate or recommend actions to correct the faults. Therefore, this research included the investigation of methods by which expert systems were developed for real-time environments and distributed systems. The focus is on the features required by real-time expert systems and the tools available to develop real-time expert systems.

  19. Distributed semantic networks and CLIPS

    NASA Technical Reports Server (NTRS)

    Snyder, James; Rodriguez, Tony

    1991-01-01

    Semantic networks of frames are commonly used as a method of reasoning in many problems. In most of these applications the semantic network exists as a single entity in a single process environment. Advances in workstation hardware provide support for more sophisticated applications involving multiple processes, interacting in a distributed environment. In these applications the semantic network may well be distributed over several concurrently executing tasks. This paper describes the design and implementation of a frame based, distributed semantic network in which frames are accessed both through C Language Integrated Production System (CLIPS) expert systems and procedural C++ language programs. The application area is a knowledge based, cooperative decision making model utilizing both rule based and procedural experts.

  20. Distributed phased array architecture study

    NASA Technical Reports Server (NTRS)

    Bourgeois, Brian

    1987-01-01

    Variations in amplifiers and phase shifters can cause degraded antenna performance, depending also on the environmental conditions and antenna array architecture. The implementation of distributed phased array hardware was studied with the aid of the DISTAR computer program as a simulation tool. This simulation provides guidance in hardware simulation. Both hard and soft failures of the amplifiers in the T/R modules are modeled. Hard failures are catastrophic: no power is transmitted to the antenna elements. Noncatastrophic or soft failures are modeled as a modified Gaussian distribution. The resulting amplitude characteristics then determine the array excitation coefficients. The phase characteristics take on a uniform distribution. Pattern characteristics such as antenna gain, half power beamwidth, mainbeam phase errors, sidelobe levels, and beam pointing errors were studied as functions of amplifier and phase shifter variations. General specifications for amplifier and phase shifter tolerances in various architecture configurations for C band and S band were determined.

  1. How robust are distributed systems

    NASA Technical Reports Server (NTRS)

    Birman, Kenneth P.

    1989-01-01

    A distributed system is made up of large numbers of components operating asynchronously from one another and hence with imcomplete and inaccurate views of one another's state. Load fluctuations are common as new tasks arrive and active tasks terminate. Jointly, these aspects make it nearly impossible to arrive at detailed predictions for a system's behavior. It is important to the successful use of distributed systems in situations in which humans cannot provide the sorts of predictable realtime responsiveness of a computer, that the system be robust. The technology of today can too easily be affected by worn programs or by seemingly trivial mechanisms that, for example, can trigger stock market disasters. Inventors of a technology have an obligation to overcome flaws that can exact a human cost. A set of principles for guiding solutions to distributed computing problems is presented.

  2. What makes distributed practice effective?

    PubMed Central

    Benjamin, Aaron S.; Tullis, Jonathan

    2010-01-01

    The advantages provided to memory by the distribution of multiple practice or study opportunities are among the most powerful effects in memory research. In this paper, we critically review the class of theories that presume contextual or encoding variability as the sole basis for the advantages of distributed practice, and recommend an alternative approach based on the idea that some study events remind learners of other study events. Encoding variability theory encounters serious challenges in two important phenomena that we review here: superadditivity and nonmonotonicity. The bottleneck in such theories lies in the assumption that mnemonic benefits arise from the increasing independence, rather than interdependence, of study opportunities. The reminding model accounts for many basic results in the literature on distributed practice, readily handles data that are problematic for encoding variability theories, including superadditivity and nonmonotonicity, and provides a unified theoretical framework for understanding the effects of repetition and the effects of associative relationships on memory. PMID:20580350

  3. Shape of Pion Distribution Amplitude

    SciTech Connect

    Radyushkin, Anatoly

    2009-11-01

    A scenario is investigated in which the leading-twist pion distribution amplitude $\\varphi_\\pi (x)$ is approximated by the pion decay constant $f_\\pi$ for all essential values of the light-cone fraction $x$. A model for the light-front wave function $\\Psi (x, k_\\perp)$ is proposed that produces such a distribution amplitude and has a rapidly decreasing (exponential for definiteness) dependence on the light-front energy combination $ k_\\perp^2/x(1-x)$. It is shown that this model easily reproduces the fit of recent large-$Q^2$ BaBar data on the photon-pion transition form factor. Some aspects of scenario with flat pion distribution amplitude are discussed.

  4. Degree distributions of growing networks.

    PubMed

    Krapivsky, P L; Rodgers, G J; Redner, S

    2001-06-01

    The in-degree and out-degree distributions of a growing network model are determined. The in-degree is the number of incoming links to a given node (and vice versa for out-degree). The network is built by (i) creation of new nodes which each immediately attach to a preexisting node, and (ii) creation of new links between preexisting nodes. This process naturally generates correlated in-degree and out-degree distributions. When the node and link creation rates are linear functions of node degree, these distributions exhibit distinct power-law forms. By tuning the parameters in these rates to reasonable values, exponents which agree with those of the web graph are obtained.

  5. Distributive Marketing Education: Innovative Instructional Techniques in Distributive Marketing Education.

    ERIC Educational Resources Information Center

    Office of Education (DHEW), Washington, DC.

    The conference featured more than 40 presentations representing existing and planned innovative programs in all levels of distributive marketing education in six States. In addition to the presentations (not reproduced in their entirety in the report), there were sessions and workshops for secondary, post secondary, and adult levels and for city…

  6. Distributed Weighted Stable Marriage Problem

    NASA Astrophysics Data System (ADS)

    Amira, Nir; Giladi, Ran; Lotker, Zvi

    The Stable Matching problem was introduced by Gale and Shapley in 1962. The input for the stable matching problem is a complete bipartite K n,n graph together with a ranking for each node. Its output is a matching that does not contain a blocking pair, where a blocking pair is a pair of elements that are not matched together but rank each other higher than they rank their current mates. In this work we study the Distributed Weighted Stable Matching problem. The input to the Weighted Stable Matching problem is a complete bipartite K n,n graph and a weight function W. The ranking of each node is determined by W, i.e. node v prefers node u 1 over node u 2 if W((v,u 1)) > W((v, u 2)). Using this ranking we can solve the original Stable Matching problem. We consider two different communication models: the billboard model and the full distributed model. In the billboard model, we assume that there is a public billboard and each participant can write one message on it in each time step. In the distributed model, we assume that each node can send O(logn) bits on each edge of the K n,n . In the billboard model we prove a somewhat surprising tight bound: any algorithm that solves the Stable Matching problem requires at least n - 1 rounds. We provide an algorithm that meets this bound. In the distributed communication model we provide an algorithm named intermediation agencies algorithm, in short (IAA), that solves the Distributed Weighted Stable Marriage problem in O(sqrt{n}) rounds. This is the first sub-linear distributed algorithm that solves some subcase of the general Stable Marriage problem.

  7. Cloud Distribution Statistics from LITE

    NASA Technical Reports Server (NTRS)

    Winker, David M.

    1998-01-01

    The Lidar In-Space Technology Experiment (LITE) mission has demonstrated the utility of spaceborne lidar in observing multilayer clouds and has provided a dataset showing the distribution of tropospheric clouds and aerosols. These unambiguous observations of the vertical distribution of clouds will allow improved verification of current cloud climatologies and GCM cloud parameterizations. Although there is now great interest in cloud profiling radar, operating in the mm-wave region, for the spacebased observation of cloud heights the results of the LITE mission have shown that satellite lidars can also make significant contributions in this area.

  8. Distributional preferences and competitive behavior.

    PubMed

    Balafoutas, Loukas; Kerschbamer, Rudolf; Sutter, Matthias

    2012-06-01

    We study experimentally the relationship between distributional preferences and competitive behavior. We find that spiteful subjects react strongest to competitive pressure and win in a tournament significantly more often than efficiency-minded and inequality averse subjects. However, when given the choice between a tournament and a piece rate scheme, efficiency-minded subjects choose the tournament most often, while spiteful and inequality averse subjects avoid it. When controlling for distributional preferences, risk attitudes and past performance, the gender gap in the willingness to compete is no longer significant, indicating that gender-related variables explain why twice as many men as women self-select into competition.

  9. Distribution of Galactic Dark Matter

    NASA Astrophysics Data System (ADS)

    Langton, Jonathan; Foss, Asa

    2001-04-01

    In this paper we examine the rotational curves of two dwarf spiral galaxies, NGC 2403 and NGC 3198. The observed rotation cannot be accounted for by luminous matter alone, therefore there must be a substantial dark component. We found the dark matter in both galaxies to be distributed according to the equation rho(r) = b*r/(r^2 + x^2). Combining this with a distribution of luminous matter rho(r)= rho(o)* e^-(a*r), we produced a rotation curve that matched the observed orbital velocities to within 4%.

  10. Modeling Nucleon Generalized Parton Distributions

    SciTech Connect

    Radyushkin, Anatoly V.

    2013-05-01

    We discuss building models for nucleon generalized parton distributions (GPDs) H and E that are based on the formalism of double distributions (DDs). We found that the usual "DD+D-term" construction should be amended by an extra term, xiE^1_+ (x,xi) built from the alpha/Beta moment of the DD e(Beta,alpha) that generates GPD E(x,xi). Unlike the D-term, this function has support in the whole -1< x<1 region, and in general does not vanish at the border points |x|=xi.

  11. Medium Effects in Parton Distributions

    SciTech Connect

    William Detmold, Huey-Wen Lin

    2011-12-01

    A defining experiment of high-energy physics in the 1980s was that of the EMC collaboration where it was first observed that parton distributions in nuclei are non-trivially related to those in the proton. This result implies that the presence of the nuclear medium plays an important role and an understanding of this from QCD has been an important goal ever since Here we investigate analogous, but technically simpler, effects in QCD and examine how the lowest moment of the pion parton distribution is modified by the presence of a Bose-condensed gas of pions or kaons.

  12. Current density distribution in PEFC

    NASA Astrophysics Data System (ADS)

    Liu, Zhixiang; Mao, Zongqiang; Wu, Bing; Wang, Lisheng; Schmidt, Volkmar M.

    The determination of the current distribution in a polymer electrolyte fuel cell (PEFC) is of great practical importance to optimize the process parameter such as the flow field design, the humidification of reaction gases and the utilization of the fuel gas. In this paper, subcells approach is used to measure current density distribution in PEFC with an active electrode area of 30 cm 2. Fuel cell performances determined under different operation conditions clearly indicate that the water balance influences the cell performance most significantly. Furthermore, it is interesting to note that under certain condition both membrane drying and electrode flooding are shown simultaneously inducing performance decaying.

  13. Shared versus distributed memory multiprocessors

    NASA Technical Reports Server (NTRS)

    Jordan, Harry F.

    1991-01-01

    The question of whether multiprocessors should have shared or distributed memory has attracted a great deal of attention. Some researchers argue strongly for building distributed memory machines, while others argue just as strongly for programming shared memory multiprocessors. A great deal of research is underway on both types of parallel systems. Special emphasis is placed on systems with a very large number of processors for computation intensive tasks and considers research and implementation trends. It appears that the two types of systems will likely converge to a common form for large scale multiprocessors.

  14. Saddlepoint distribution function approximations in biostatistical inference.

    PubMed

    Kolassa, J E

    2003-01-01

    Applications of saddlepoint approximations to distribution functions are reviewed. Calculations are provided for marginal distributions and conditional distributions. These approximations are applied to problems of testing and generating confidence intervals, particularly in canonical exponential families.

  15. Standard Distributions: One Graph Fits All

    ERIC Educational Resources Information Center

    Wagner, Clifford H.

    2007-01-01

    Standard distributions are ubiquitous but not unique. With suitable scaling, the graph of a standard distribution serves as the graph for every distribution in the family. The standard exponential can easily be taught in elementary statistics courses.

  16. Avoiding Distribution System Upgrade Costs Using Distributed Generation

    SciTech Connect

    Schienbein, Lawrence A.; Balducci, Patrick J.; Nguyen, Tony B.; Brown, Daryl R.; DeSteese, John G.; Speer, Gregory A.

    2004-01-20

    PNNL, in cooperation with three utilities, developed a database and methodology to analyze and characterize the avoided costs of Distributed Generation (DG) deployment as an alternative to traditional distribution system investment. After applying a number of screening criteria to the initial set of 307 cases, eighteen were selected for detailed analysis. Alternative DG investment scenarios were developed for these cases to permit capital, operation, maintenance, and fuel costs to be identified and incorporated into the analysis. The “customer-owned” backup power generator option was also investigated. The results of the analysis of the 18 cases show that none yielded cost savings under the alternative DG scenarios. However, the DG alternative systems were configured using very restrictive assumptions concerning reliability, peak rating, engine types and acceptable fuel. In particular it was assumed that the DG alternative in each case must meet the reliability required of conventional distribution systems (99.91% reliability). The analysis was further constrained by a requirement that each substation meet the demands placed upon it by a one in three weather occurrence. To determine if, by relaxing these requirements, the DG alternative might be more viable, one project was re-examined. The 99.91% reliability factor was still assumed for normal operating conditions but redundancy required to maintain reliability was relaxed for the relatively few hours every three years where extreme weather caused load to exceed present substation capacity. This resulted in the deferment of capital investment until later years and reduced the number of engines required for the project. The cost of both the conventional and DG alternative also dropped because the centralized power generation, variable O&M, and DG fuels costs were calculated based on present load requirements in combination with long-term forecasts of load growth, as opposed to load requirements plus a buffer

  17. Size Distribution of Bacterial Cells

    PubMed Central

    Stull, V. R.

    1972-01-01

    By using differential light-scattering measurements of single cells suspended in a laser beam, an effective cell radius has been determined for 141 individual bacteria from suspensions of Staphylococcus epidermidis. The accumulation of these measurements has provided the size distribution for the sampling. PMID:4551753

  18. Distributed Learning and Institutional Restructuring.

    ERIC Educational Resources Information Center

    Hawkins, Brian L.

    1999-01-01

    Discusses the following challenges institutions must consider as they enter the new marketplace of distributed learning: library access, faculty workload, faculty incentives, faculty-support structures, intellectual property, articulation agreements, financial aid, pricing, cross-subsidization of programs, institutional loyalty and philanthropy,…

  19. Sex Differences and Distributive Fairness.

    ERIC Educational Resources Information Center

    Russ, Terry Lee; Alexander, Sheldon

    In research on equity and justice some investigators have reported that men and women use different allocation norms in distributing rewards; men using an equity rule and women an equality rule, while others conclude that such sex differences in reward allocation appear primarily when the allocator is also a co-recipient of the reward. The present…

  20. Distributed user services for supercomputers

    NASA Technical Reports Server (NTRS)

    Sowizral, Henry A.

    1989-01-01

    User-service operations at supercomputer facilities are examined. The question is whether a single, possibly distributed, user-services organization could be shared by NASA's supercomputer sites in support of a diverse, geographically dispersed, user community. A possible structure for such an organization is identified as well as some of the technologies needed in operating such an organization.

  1. Age distribution of anginose mononucleosis.

    PubMed Central

    Spirer, Z; Holtzman, M; Melamed, I; Shalit, I

    1987-01-01

    The age distribution of anginose infectious mononucleosis in children was analysed retrospectively for the years 1966-85. During that period the disease became significantly more common in children of a young age and less common in older children. This shift could not be attributed either to socioeconomic conditions or to the diagnostic methods used. PMID:3619480

  2. Parallel, Distributed Scripting with Python

    SciTech Connect

    Miller, P J

    2002-05-24

    Parallel computers used to be, for the most part, one-of-a-kind systems which were extremely difficult to program portably. With SMP architectures, the advent of the POSIX thread API and OpenMP gave developers ways to portably exploit on-the-box shared memory parallelism. Since these architectures didn't scale cost-effectively, distributed memory clusters were developed. The associated MPI message passing libraries gave these systems a portable paradigm too. Having programmers effectively use this paradigm is a somewhat different question. Distributed data has to be explicitly transported via the messaging system in order for it to be useful. In high level languages, the MPI library gives access to data distribution routines in C, C++, and FORTRAN. But we need more than that. Many reasonable and common tasks are best done in (or as extensions to) scripting languages. Consider sysadm tools such as password crackers, file purgers, etc ... These are simple to write in a scripting language such as Python (an open source, portable, and freely available interpreter). But these tasks beg to be done in parallel. Consider the a password checker that checks an encrypted password against a 25,000 word dictionary. This can take around 10 seconds in Python (6 seconds in C). It is trivial to parallelize if you can distribute the information and co-ordinate the work.

  3. Career Information: Marketing and Distribution.

    ERIC Educational Resources Information Center

    American Vocational Association, Inc., Washington, DC.

    The publication is a bibliography prepared in an attempt to assist guidance and distributive education personnel in their task of securing relevant published career information. Depending on overall adequacy, three categories of the National Vocational Guidance Association (NVGA)--highly recommended, recommended, and useful--were used in rating…

  4. Modeling Natural Variation through Distribution

    ERIC Educational Resources Information Center

    Lehrer, Richard; Schauble, Leona

    2004-01-01

    This design study tracks the development of student thinking about natural variation as late elementary grade students learned about distribution in the context of modeling plant growth at the population level. The data-modeling approach assisted children in coordinating their understanding of particular cases with an evolving notion of data as an…

  5. Automated Power-Distribution System

    NASA Technical Reports Server (NTRS)

    Ashworth, Barry; Riedesel, Joel; Myers, Chris; Miller, William; Jones, Ellen F.; Freeman, Kenneth; Walsh, Richard; Walls, Bryan K.; Weeks, David J.; Bechtel, Robert T.

    1992-01-01

    Autonomous power-distribution system includes power-control equipment and automation equipment. System automatically schedules connection of power to loads and reconfigures itself when it detects fault. Potential terrestrial applications include optimization of consumption of power in homes, power supplies for autonomous land vehicles and vessels, and power supplies for automated industrial processes.

  6. Requiring Collaboration or Distributing Leadership?

    ERIC Educational Resources Information Center

    Kennedy, Anne; Deuel, Angie; Nelson, Tamara Holmlund; Slavit, David

    2011-01-01

    Through the process of initiating, implementing, and sustaining a schoolwide professional learning community (PLC), teachers and administrators at the pseudonymous Silver Valley Middle School provide a powerful example of distributed leadership in action. New leadership roles, coordination, and interdependency among staff have led to an increased…

  7. A distributed telerobotics construction set

    NASA Technical Reports Server (NTRS)

    Wise, James D.

    1994-01-01

    During the course of our research on distributed telerobotic systems, we have assembled a collection of generic, reusable software modules and an infrastructure for connecting them to form a variety of telerobotic configurations. This paper describes the structure of this 'Telerobotics Construction Set' and lists some of the components which comprise it.

  8. Distributed Leadership in Educational Institutions

    ERIC Educational Resources Information Center

    Göksoy, Süleyman

    2015-01-01

    In recent years, many studies are conducted about shared leadership process. Distributed leadership (DL) approach addresses leadership along with teams, groups and organizational characteristics. In practice, this approach objects the supposition that an individual should take the lead in order to ensure change. Proponents of this idea claim that…

  9. Prior Distributions on Symmetric Groups

    ERIC Educational Resources Information Center

    Gupta, Jayanti; Damien, Paul

    2005-01-01

    Fully and partially ranked data arise in a variety of contexts. From a Bayesian perspective, attention has focused on distance-based models; in particular, the Mallows model and extensions thereof. In this paper, a class of prior distributions, the "Binary Tree," is developed on the symmetric group. The attractive features of the class are: it…

  10. Educational Micropolitics and Distributed Leadership

    ERIC Educational Resources Information Center

    Flessa, Joseph

    2009-01-01

    This article critically reviews two bodies of literature that potentially share common concerns, yet rarely overlap: distributed leadership and educational micropolitics. Alternative explanations for the split between these two analytical approaches to school organization are explored in sections on problem framing, methodology, and the…

  11. Tools for distributed application management

    NASA Technical Reports Server (NTRS)

    Marzullo, Keith; Wood, Mark; Cooper, Robert; Birman, Kenneth P.

    1990-01-01

    Distributed application management consists of monitoring and controlling an application as it executes in a distributed environment. It encompasses such activities as configuration, initialization, performance monitoring, resource scheduling, and failure response. The Meta system is described: a collection of tools for constructing distributed application management software. Meta provides the mechanism, while the programmer specifies the policy for application management. The policy is manifested as a control program which is a soft real time reactive program. The underlying application is instrumented with a variety of built-in and user defined sensors and actuators. These define the interface between the control program and the application. The control program also has access to a database describing the structure of the application and the characteristics of its environment. Some of the more difficult problems for application management occur when pre-existing, nondistributed programs are integrated into a distributed application for which they may not have been intended. Meta allows management functions to be retrofitted to such programs with a minimum of effort.

  12. Tools for distributed application management

    NASA Technical Reports Server (NTRS)

    Marzullo, Keith; Cooper, Robert; Wood, Mark; Birman, Kenneth P.

    1990-01-01

    Distributed application management consists of monitoring and controlling an application as it executes in a distributed environment. It encompasses such activities as configuration, initialization, performance monitoring, resource scheduling, and failure response. The Meta system (a collection of tools for constructing distributed application management software) is described. Meta provides the mechanism, while the programmer specifies the policy for application management. The policy is manifested as a control program which is a soft real-time reactive program. The underlying application is instrumented with a variety of built-in and user-defined sensors and actuators. These define the interface between the control program and the application. The control program also has access to a database describing the structure of the application and the characteristics of its environment. Some of the more difficult problems for application management occur when preexisting, nondistributed programs are integrated into a distributed application for which they may not have been intended. Meta allows management functions to be retrofitted to such programs with a minimum of effort.

  13. Cooperative distributed architecture for mashups

    NASA Astrophysics Data System (ADS)

    Al-Haj Hassan, Osama Mohammad; Ramaswamy, Lakshmish; Hamad, Fadi; Abu Taleb, Anas

    2014-05-01

    Since the advent of Web 2.0, personalised applications such as mashups have become widely popular. Mashups enable end-users to fetch data from distributed data sources, and refine it based on their personal needs. This high degree of personalisation that mashups offer comes at the expense of performance and scalability. These scalability challenges are exacerbated by the centralised architectures of current mashup platforms. In this paper, we address the performance and scalability issues by designing CoMaP - a distributed mashup platform. CoMaP's architecture comprises of several cooperative mashup processing nodes distributed over the Internet upon which mashups can, fully or partially, be executed. CoMaP incorporates a dynamic and efficient scheme for deploying mashups on the processing nodes. Our scheme considers a number of parameters such as variations in link delays and bandwidths, and loads on mashup processing nodes. CoMaP includes effective and low-cost mechanisms for balancing loads on the processing nodes as well for handling node failures. Furthermore, we propose novel techniques that leverage keyword synonyms, ontologies and caching to enhance end-user experience. This paper reports several experiments to comprehensively study CoMaP's performance. The results demonstrate CoMaP's benefits as a scalable distributed mashup platform.

  14. Entropy content of multiplicity distributions

    NASA Astrophysics Data System (ADS)

    Lam, C. S.

    1989-02-01

    We argue that the entropy S is an important variable to consider for multiparticle productions. A prediction of the width parameter 1//k of multiplicity distributions can be made at superhigh energies by extrapolating the entropy variable S, considered as a function of the average multiplicity Nmacr;. This is done explicitly for the negative binomial distributions and the Furry-Yule distributions, though the method is applicable to other distributions. We also argue that direct extrapolation in the variable 1//k is not advisable. Further evidence for SSZ scaling is given, and a power law for the average multiplicity N¯ as a function of the collision energy √s is derived. It is a pleasure to thank Rudy Hwa and David Kiang for discussions and help. I am also grateful to Dr. V. Šimák and Dr. M. Šumbera for a correspondence pointing out a numerical error in the earlier version of this work. This work is supported in part by the Natural Science and Engineering Research Council of Canada and the Québec Department of Education.

  15. Distribute Education on the Upswing

    ERIC Educational Resources Information Center

    Brown, T. Carl

    1976-01-01

    This fragment of vocational education history reviews the early struggles of distributive education (DE) to win recognition from Congress, the public, and the retail industry, and goes on to describe the breakthrough that came with the formation of DE's National Management Advisory Council. (Editor/HD)

  16. Decoy State Quantum Key Distribution

    NASA Astrophysics Data System (ADS)

    Lo, Hoi-Kwong

    2005-10-01

    Quantum key distribution (QKD) allows two parties to communicate in absolute security based on the fundamental laws of physics. Up till now, it is widely believed that unconditionally secure QKD based on standard Bennett-Brassard (BB84) protocol is limited in both key generation rate and distance because of imperfect devices. Here, we solve these two problems directly by presenting new protocols that are feasible with only current technology. Surprisingly, our new protocols can make fiber-based QKD unconditionally secure at distances over 100km (for some experiments, such as GYS) and increase the key generation rate from O(η2) in prior art to O(η) where η is the overall transmittance. Our method is to develop the decoy state idea (first proposed by W.-Y. Hwang in "Quantum Key Distribution with High Loss: Toward Global Secure Communication", Phys. Rev. Lett. 91, 057901 (2003)) and consider simple extensions of the BB84 protocol. This part of work is published in "Decoy State Quantum Key Distribution", . We present a general theory of the decoy state protocol and propose a decoy method based on only one signal state and two decoy states. We perform optimization on the choice of intensities of the signal state and the two decoy states. Our result shows that a decoy state protocol with only two types of decoy states--a vacuum and a weak decoy state--asymptotically approaches the theoretical limit of the most general type of decoy state protocols (with an infinite number of decoy states). We also present a one-decoy-state protocol as a special case of Vacuum+Weak decoy method. Moreover, we provide estimations on the effects of statistical fluctuations and suggest that, even for long distance (larger than 100km) QKD, our two-decoy-state protocol can be implemented with only a few hours of experimental data. In conclusion, decoy state quantum key distribution is highly practical. This part of work is

  17. The neutron star mass distribution

    SciTech Connect

    Kiziltan, Bülent; Kottas, Athanasios; De Yoreo, Maria; Thorsett, Stephen E.

    2013-11-20

    In recent years, the number of pulsars with secure mass measurements has increased to a level that allows us to probe the underlying neutron star (NS) mass distribution in detail. We critically review the radio pulsar mass measurements. For the first time, we are able to analyze a sizable population of NSs with a flexible modeling approach that can effectively accommodate a skewed underlying distribution and asymmetric measurement errors. We find that NSs that have evolved through different evolutionary paths reflect distinctive signatures through dissimilar distribution peak and mass cutoff values. NSs in double NS and NS-white dwarf (WD) systems show consistent respective peaks at 1.33 M {sub ☉} and 1.55 M {sub ☉}, suggesting significant mass accretion (Δm ≈ 0.22 M {sub ☉}) has occurred during the spin-up phase. The width of the mass distribution implied by double NS systems is indicative of a tight initial mass function while the inferred mass range is significantly wider for NSs that have gone through recycling. We find a mass cutoff at ∼2.1 M {sub ☉} for NSs with WD companions, which establishes a firm lower bound for the maximum NS mass. This rules out the majority of strange quark and soft equation of state models as viable configurations for NS matter. The lack of truncation close to the maximum mass cutoff along with the skewed nature of the inferred mass distribution both enforce the suggestion that the 2.1 M {sub ☉} limit is set by evolutionary constraints rather than nuclear physics or general relativity, and the existence of rare supermassive NSs is possible.

  18. Gaussian Velocity Distributions in Avalanches

    NASA Astrophysics Data System (ADS)

    Shattuck, Mark

    2004-03-01

    Imagine a world where gravity is so strong that if an ice cube is tilted the shear forces melt the surface and water avalanches down. Further imagine that the ambient temperature is so low that the water re-freezes almost immediately. This is the world of granular flows. As a granular solid is tilted the surface undergoes a sublimation phase transition and a granular gas avalanches down the surface, but the inelastic collisions rapidly remove energy from the flow lowering the granular temperature (kinetic energy per particle) until the gas solidifies again. It is under these extreme conditions that we attempt to uncover continuum granular flow properties. Typical continuum theories like Navier-Stokes equation for fluids follow the space-time evolution of the first few moments of the velocity distribution. We study continuously avalanching flow in a rotating two-dimensional granular drum using high-speed video imaging and extract the position and velocities of the particles. We find a universal near Gaussian velocity distribution throughout the flowing regions, which are characterized by a liquid-like radial distribution function. In the remaining regions, in which the radial distribution function develops sharp crystalline peaks, the velocity distribution has a Gaussian peak but is much broader in the tails. In a companion experiment on a vibrated two-dimensional granular fluid under constant pressure, we find a clear gas-solid phase transition in which both the temperature and density change discontinuously. This suggests that a low temperature crystal and a high temperature gas can coexist in steady state. This coexistence could result in a narrower, cooler, Gaussian peak and a broader, warmer, Gaussian tail like the non-Gaussian behavior seen in the crystalline portions of the rotating drum.

  19. Distributed intelligence in an astronomical Distributed Sensor Network

    NASA Astrophysics Data System (ADS)

    White, R. R.; Davis, H.; Vestrand, W. T.; Wozniak, P. R.

    2008-03-01

    The Telescope Alert Operations Network System (TALONS) was designed and developed in the year 2000, around the architectural principles of a distributed sensor network. This network supported the original Rapid Telescopes for Optical Response (RAPTOR) project goals; however, only with further development could TALONS meet the goals of the larger Thinking Telescope Project. The complex objectives of the Thinking Telescope project required a paradigm shift in the software architecture - the centralised intelligence merged into the TALONS network operations could no longer meet all of the new requirements. The intelligence needed to be divorced from the network operations and developed as a series of peripheral intelligent agents, distributing the decision making and analytical processes based on the temporal volatility of the data. This paper is presented as only one part of the poster from the workshop and in it we will explore the details of this architecture and how that merges with the current Thinking Telescope system to meet our project goals.

  20. Mixture of Skewed α-Stable Distributions

    NASA Astrophysics Data System (ADS)

    Shojaei, S. R. Hosseini; Nassiri, V.; Mohammadian, Gh. R.; Mohammadpour, A.

    2011-03-01

    Expectation maximization (EM) algorithm and the Bayesian techniques are two approaches for statistical inference of mixture models [3, 4]. By noting the advantages of the Bayesian methods, practitioners prefer them. However, implementing Markov chain Monte Carlo algorithms can be very complicated for stable distributions, due to the non-analytic density or distribution function formulas. In this paper, we introduce a new class of mixture of heavy-tailed distributions, called mixture of skewed stable distributions. Skewed stable distributions belongs to the exponential family and they have analytic density representation. It is shown that skewed stable distributions dominate skew stable distribution functions and they can be used to model heavy-tailed data. The class of skewed stable distributions has an analytic representation for its density function and the Bayesian inference can be done similar to the exponential family of distributions. Finally, mixture of skewed stable distributions are compared to the mixture of stable distributions through a simulations study.

  1. 26 CFR 1.643(a)-0 - Distributable net income; deduction for distributions; in general.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... § 1.643(a)-0 Distributable net income; deduction for distributions; in general. The term distributable... character of distributions to the beneficiaries. Distributable net income means for any taxable year, the... 26 Internal Revenue 8 2010-04-01 2010-04-01 false Distributable net income; deduction...

  2. Distribution Integrity Management Plant (DIMP)

    SciTech Connect

    Gonzales, Jerome F.

    2012-05-07

    This document is the distribution integrity management plan (Plan) for the Los Alamos National Laboratory (LANL) Natural Gas Distribution System. This Plan meets the requirements of 49 CFR Part 192, Subpart P Distribution Integrity Management Programs (DIMP) for the LANL Natural Gas Distribution System. This Plan was developed by reviewing records and interviewing LANL personnel. The records consist of the design, construction, operation and maintenance for the LANL Natural Gas Distribution System. The records system for the LANL Natural Gas Distribution System is limited, so the majority of information is based on the judgment of LANL employees; the maintenance crew, the Corrosion Specialist and the Utilities and Infrastructure (UI) Civil Team Leader. The records used in this report are: Pipeline and Hazardous Materials Safety Administration (PHMSA) 7100.1-1, Report of Main and Service Line Inspection, Natural Gas Leak Survey, Gas Leak Response Report, Gas Leak and Repair Report, and Pipe-to-Soil Recordings. The specific elements of knowledge of the infrastructure used to evaluate each threat and prioritize risks are listed in Sections 6 and 7, Threat Evaluation and Risk Prioritization respectively. This Plan addresses additional information needed and a method for gaining that data over time through normal activities. The processes used for the initial assessment of Threat Evaluation and Risk Prioritization are the methods found in the Simple, Handy Risk-based Integrity Management Plan (SHRIMP{trademark}) software package developed by the American Pipeline and Gas Agency (APGA) Security and Integrity Foundation (SIF). SHRIMP{trademark} uses an index model developed by the consultants and advisors of the SIF. Threat assessment is performed using questions developed by the Gas Piping Technology Company (GPTC) as modified and added to by the SHRIMP{trademark} advisors. This Plan is required to be reviewed every 5 years to be continually refined and improved. Records

  3. Enhanced distributed energy resource system

    DOEpatents

    Atcitty, Stanley; Clark, Nancy H.; Boyes, John D.; Ranade, Satishkumar J.

    2007-07-03

    A power transmission system including a direct current power source electrically connected to a conversion device for converting direct current into alternating current, a conversion device connected to a power distribution system through a junction, an energy storage device capable of producing direct current connected to a converter, where the converter, such as an insulated gate bipolar transistor, converts direct current from an energy storage device into alternating current and supplies the current to the junction and subsequently to the power distribution system. A microprocessor controller, connected to a sampling and feedback module and the converter, determines when the current load is higher than a set threshold value, requiring triggering of the converter to supply supplemental current to the power transmission system.

  4. Hazards Data Distribution System (HDDS)

    USGS Publications Warehouse

    Jones, Brenda; Lamb, Rynn M.

    2015-07-09

    When emergencies occur, first responders and disaster response teams often need rapid access to aerial photography and satellite imagery that is acquired before and after the event. The U.S. Geological Survey (USGS) Hazards Data Distribution System (HDDS) provides quick and easy access to pre- and post-event imagery and geospatial datasets that support emergency response and recovery operations. The HDDS provides a single, consolidated point-of-entry and distribution system for USGS-hosted remotely sensed imagery and other geospatial datasets related to an event response. The data delivery services are provided through an interactive map-based interface that allows emergency response personnel to rapidly select and download pre-event ("baseline") and post-event emergency response imagery.

  5. Nation Radiobiology Archives Distributed Access

    SciTech Connect

    Smith, S. K.; Prather, J. C.; Ligotke, E. K.; Watson, C. R.

    1992-06-01

    NRADA1.1 is a supplement to NRADA1.0. This version eliminates several bugs, and includes a few new features. The diskettes consist of a distributed subset of information representative of the extensive NRA databases and database access software maintained at the Pacific Northwest Laboratory which provide an introduction to the scope and style of the NRA Information Systems. Information in the NRA Summary, Inventory, and Bibliographic database is available upon request. Printed reports have been provided in the past. The completion of the NRADA1.1 is the realization of a long standing goal of the staff and advisory committee. Information may be easily distributed to the user in an electronic form which preserves the relationships between the various databases.

  6. Probability distributions for multimeric systems.

    PubMed

    Albert, Jaroslav; Rooman, Marianne

    2016-01-01

    We propose a fast and accurate method of obtaining the equilibrium mono-modal joint probability distributions for multimeric systems. The method necessitates only two assumptions: the copy number of all species of molecule may be treated as continuous; and, the probability density functions (pdf) are well-approximated by multivariate skew normal distributions (MSND). Starting from the master equation, we convert the problem into a set of equations for the statistical moments which are then expressed in terms of the parameters intrinsic to the MSND. Using an optimization package on Mathematica, we minimize a Euclidian distance function comprising of a sum of the squared difference between the left and the right hand sides of these equations. Comparison of results obtained via our method with those rendered by the Gillespie algorithm demonstrates our method to be highly accurate as well as efficient.

  7. Estimators for the Cauchy distribution

    SciTech Connect

    Hanson, K.M.; Wolf, D.R.

    1993-12-31

    We discuss the properties of various estimators of the central position of the Cauchy distribution. The performance of these estimators is evaluated for a set of simulated experiments. Estimators based on the maximum and mean of the posterior probability density function are empirically found to be well behaved when more than two measurements are available. On the contrary, because of the infinite variance of the Cauchy distribution, the average of the measured positions is an extremely poor estimator of the location of the source. However, the median of the measured positions is well behaved. The rms errors for the various estimators are compared to the Fisher-Cramer-Rao lower bound. We find that the square root of the variance of the posterior density function is predictive of the rms error in the mean posterior estimator.

  8. Antenna structure with distributed strip

    DOEpatents

    Rodenbeck, Christopher T.

    2008-10-21

    An antenna comprises electrical conductors arranged to form a radiating element including a folded line configuration and a distributed strip configuration, where the radiating element is in proximity to a ground conductor. The folded line and the distributed strip can be electrically interconnected and substantially coplanar. The ground conductor can be spaced from, and coplanar to, the radiating element, or can alternatively lie in a plane set at an angle to the radiating element. Embodiments of the antenna include conductor patterns formed on a printed wiring board, having a ground plane, spacedly adjacent to and coplanar with the radiating element. Other embodiments of the antenna comprise a ground plane and radiating element on opposed sides of a printed wiring board. Other embodiments of the antenna comprise conductors that can be arranged as free standing "foils". Other embodiments include antennas that are encapsulated into a package containing the antenna.

  9. Antenna structure with distributed strip

    DOEpatents

    Rodenbeck, Christopher T.

    2008-03-18

    An antenna comprises electrical conductors arranged to form a radiating element including a folded line configuration and a distributed strip configuration, where the radiating element is in proximity to a ground conductor. The folded line and the distributed strip can be electrically interconnected and substantially coplanar. The ground conductor can be spaced from, and coplanar to, the radiating element, or can alternatively lie in a plane set at an angle to the radiating element. Embodiments of the antenna include conductor patterns formed on a printed wiring board, having a ground plane, spacedly adjacent to and coplanar with the radiating element. Other embodiments of the antenna comprise a ground plane and radiating element on opposed sides of a printed wiring board. Other embodiments of the antenna comprise conductors that can be arranged as free standing "foils". Other embodiments include antennas that are encapsulated into a package containing the antenna.

  10. Nation Radiobiology Archives Distributed Access

    1992-06-01

    NRADA1.1 is a supplement to NRADA1.0. This version eliminates several bugs, and includes a few new features. The diskettes consist of a distributed subset of information representative of the extensive NRA databases and database access software maintained at the Pacific Northwest Laboratory which provide an introduction to the scope and style of the NRA Information Systems. Information in the NRA Summary, Inventory, and Bibliographic database is available upon request. Printed reports have been provided inmore » the past. The completion of the NRADA1.1 is the realization of a long standing goal of the staff and advisory committee. Information may be easily distributed to the user in an electronic form which preserves the relationships between the various databases.« less

  11. Digitally controlled distributed phase shifter

    SciTech Connect

    Hietala, V.M.; Kravitz, S.H.; Vawter, G.A.

    1992-12-31

    A digitally controlled distributed phase shifter is comprised of N phase shifters. Digital control is achieved by using N binary length-weighted electrodes located on the top surface of a waveguide. A control terminal is attached to each electrode thereby allowing the application of a control signal. The control signal is either one of two discrete bias voltages. The application of the discrete bias voltages change the modal index of a portion of the waveguide that corresponds to a length of the electrode to which the bias voltage is applied, thereby causing the phase to change through the underlying portion of the waveguide. The digitally controlled distributed phase shift network has a total phase shift comprised of the sum of the individual phase shifters.

  12. Distributed antenna system and method

    NASA Technical Reports Server (NTRS)

    Fink, Patrick W. (Inventor); Dobbins, Justin A. (Inventor)

    2004-01-01

    System and methods are disclosed for employing one or more radiators having non-unique phase centers mounted to a body with respect to a plurality of transmitters to determine location characteristics of the body such as the position and/or attitude of the body. The one or more radiators may consist of a single, continuous element or of two or more discrete radiation elements whose received signals are combined. In a preferred embodiment, the location characteristics are determined using carrier phase measurements whereby phase center information may be determined or estimated. A distributed antenna having a wide angle view may be mounted to a moveable body in accord with the present invention. The distributed antenna may be utilized for maintaining signal contact with multiple spaced apart transmitters, such as a GPS constellation, as the body rotates without the need for RF switches to thereby provide continuous attitude and position determination of the body.

  13. Chemical elements distribution in cells

    NASA Astrophysics Data System (ADS)

    Ortega, R.

    2005-04-01

    Analysing, imaging and understanding the cellular chemistry, from macromolecules to monoatomic elements, is probably a major challenge for the scientific community after the conclusion of the genome project. In order to probe the distribution of elements in cells, especially the so-called inorganic elements, it is necessary to apply microanalytical techniques with sub-micrometer resolution and high chemical sensitivity. This paper presents the current status of chemical element imaging inside cells, and a comparison of the different analytical techniques available: nuclear microprobe, electron microprobe and electron energy loss spectroscopy, synchrotron radiation microprobe, secondary ion mass spectrometry and fluorescence microscopy methods. Examples of intracellular chemical elements distributions relevant to cancer pharmacology, medical imaging, metal carcinogenesis and neuropathology studies obtained by nuclear microprobe and other microanalytical techniques are presented.

  14. Secure key storage and distribution

    DOEpatents

    Agrawal, Punit

    2015-06-02

    This disclosure describes a distributed, fault-tolerant security system that enables the secure storage and distribution of private keys. In one implementation, the security system includes a plurality of computing resources that independently store private keys provided by publishers and encrypted using a single security system public key. To protect against malicious activity, the security system private key necessary to decrypt the publication private keys is not stored at any of the computing resources. Rather portions, or shares of the security system private key are stored at each of the computing resources within the security system and multiple security systems must communicate and share partial decryptions in order to decrypt the stored private key.

  15. Parameterizing the Raindrop Size Distribution

    NASA Technical Reports Server (NTRS)

    Haddad, Ziad S.; Durden, Stephen L.; Im, Eastwood

    1996-01-01

    This paper addresses the problem of finding a parametric form for the raindrop size distribution (DSD) that(1) is an appropriate model for tropical rainfall, and (2) involves statistically independent parameters. Such a parameterization is derived in this paper. One of the resulting three "canonical" parameters turns out to vary relatively little, thus making the parameterization particularly useful for remote sensing applications. In fact, a new set of r drop-size-distribution-based Z-R and k-R relations is obtained. Only slightly more complex than power laws, they are very good approximations to the exact radar relations one would obtain using Mie scattering. The coefficients of the new relations are directly related to the shape parameters of the particular DSD that one starts with. Perhaps most important, since the coefficients are independent of the rain rate itself, the relations are ideally suited for rain retrieval algorithms.

  16. Distribution-free discriminant analysis

    SciTech Connect

    Burr, T.; Doak, J.

    1997-05-01

    This report describes our experience in implementing a non-parametric (distribution-free) discriminant analysis module for use in a wide range of pattern recognition problems. Issues discussed include performance results on both real and simulated data sets, comparisons to other methods, and the computational environment. In some cases, this module performs better than other existing methods. Nearly all cases can benefit from the application of multiple methods.

  17. SAMICS marketing and distribution model

    NASA Technical Reports Server (NTRS)

    1978-01-01

    A SAMICS (Solar Array Manufacturing Industry Costing Standards) was formulated as a computer simulation model. Given a proper description of the manufacturing technology as input, this model computes the manufacturing price of solar arrays for a broad range of production levels. This report presents a model for computing these marketing and distribution costs, the end point of the model being the loading dock of the final manufacturer.

  18. Thermophoretic depletion follows Boltzmann distribution.

    PubMed

    Duhr, Stefan; Braun, Dieter

    2006-04-28

    Thermophoresis, also termed thermal diffusion or the Soret effect, moves particles along temperature gradients. For particles in liquids, the effect lacks a theoretical explanation. We present experimental results at moderate thermal gradients: (i) Thermophoretic depletion of 200 nm polystyrene spheres in water follows an exponential distribution over 2 orders of magnitude in concentration; (ii) Soret coefficients scale linearly with the sphere's surface area. Based on the experiments, it is argued that local thermodynamic equilibrium is a good starting point to describe thermophoresis.

  19. The data distribution satellite system

    NASA Technical Reports Server (NTRS)

    Bruno, Ronald C.; Weinberg, Aaron

    1991-01-01

    The Data Distributed Satellite (DDS) will be capable of providing the space research community with inexpensive and easy access to space payloads and space data. Furthermore, the DDS is shown to be a natural outgrowth of advances and evolution in both NASA's Space Network and commercial satellite communications. The roadmap and timescale for this evolution is described along with key demonstrations, proof-of-concept models, and required technology development that will support the projected system evolution toward the DDS.

  20. 30 CFR 57.12006 - Distribution boxes.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Distribution boxes. 57.12006 Section 57.12006... and Underground § 57.12006 Distribution boxes. Distribution boxes shall be provided with a... deenergized, and the distribution box shall be labeled to show which circuit each device controls....

  1. 30 CFR 57.12006 - Distribution boxes.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Distribution boxes. 57.12006 Section 57.12006... and Underground § 57.12006 Distribution boxes. Distribution boxes shall be provided with a... deenergized, and the distribution box shall be labeled to show which circuit each device controls....

  2. 30 CFR 57.12006 - Distribution boxes.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Distribution boxes. 57.12006 Section 57.12006... and Underground § 57.12006 Distribution boxes. Distribution boxes shall be provided with a... deenergized, and the distribution box shall be labeled to show which circuit each device controls....

  3. 14 CFR 25.1355 - Distribution system.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Equipment Electrical Systems and Equipment § 25.1355 Distribution system. (a) The distribution system includes the distribution busses, their associated feeders... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Distribution system. 25.1355 Section...

  4. 14 CFR 29.1355 - Distribution system.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Equipment Electrical Systems and Equipment § 29.1355 Distribution system. (a) The distribution system includes the distribution busses, their associated feeders... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Distribution system. 29.1355 Section...

  5. 14 CFR 29.1355 - Distribution system.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Equipment Electrical Systems and Equipment § 29.1355 Distribution system. (a) The distribution system includes the distribution busses, their associated feeders... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Distribution system. 29.1355 Section...

  6. 14 CFR 25.1355 - Distribution system.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Equipment Electrical Systems and Equipment § 25.1355 Distribution system. (a) The distribution system includes the distribution busses, their associated feeders... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Distribution system. 25.1355 Section...

  7. World-wide distribution automation systems

    SciTech Connect

    Devaney, T.M.

    1994-12-31

    A worldwide power distribution automation system is outlined. Distribution automation is defined and the status of utility automation is discussed. Other topics discussed include a distribution management system, substation feeder, and customer functions, potential benefits, automation costs, planning and engineering considerations, automation trends, databases, system operation, computer modeling of system, and distribution management systems.

  8. Building a generalized distributed system model

    NASA Technical Reports Server (NTRS)

    Mukkamala, Ravi

    1991-01-01

    A number of topics related to building a generalized distributed system model are discussed. The effects of distributed database modeling on evaluation of transaction rollbacks, the measurement of effects of distributed database models on transaction availability measures, and a performance analysis of static locking in replicated distributed database systems are covered.

  9. Statistical Physics for Adaptive Distributed Control

    NASA Technical Reports Server (NTRS)

    Wolpert, David H.

    2005-01-01

    A viewgraph presentation on statistical physics for distributed adaptive control is shown. The topics include: 1) The Golden Rule; 2) Advantages; 3) Roadmap; 4) What is Distributed Control? 5) Review of Information Theory; 6) Iterative Distributed Control; 7) Minimizing L(q) Via Gradient Descent; and 8) Adaptive Distributed Control.

  10. Redshifts distribution in A262

    NASA Astrophysics Data System (ADS)

    Hassan, M. S. R.; Abidin, Z. Z.; Ibrahim, U. F. S. U.; Hashim, N.; Lee, D. A. A.

    2016-05-01

    Galaxy clusters are the largest virialized systems in the Universe containing a collection of galaxies of different redshifts. The redshift distribution of galaxies in galaxy clusters is concentrated at a certain redshift range which remarkably tells us that only the galaxies in a certain radial range belong to the galaxy cluster. This leads to a boundary estimation of the cluster. Background and foreground systems are represented by a histogram that determines whether some of the galaxies are too far or too high in redshift to be counted as the member of the cluster. With the recent advances in multifibre spectroscopy, it has become possible to perform detailed analysis of the redshift distribution of several galaxy clusters in the Abell Catalogue. This has given rise to significantly improved estimates of cluster membership, extent and dynamical history. Here we present a spectroscopic analysis of the galaxy cluster A262. We find 55 galaxies fall within z = 0.0143 and 0.0183 with velocity range 4450-5300 km s-1, and are therefore members of the cluster. We derived a new mean redshift of z = 0.016 173 ± 0.000 074 (4852 ± 22 km s-1) for the system of which we compare with our neutral hydrogen (H I) detection which peaks at 4970 ± 0.5 km s-1. It is found that the distribution of H I tends to be located at the edge of the cluster since most of spiral rich galaxies were away from cluster centre.

  11. Distributed Relaxation for Conservative Discretizations

    NASA Technical Reports Server (NTRS)

    Diskin, Boris; Thomas, James L.

    2001-01-01

    A multigrid method is defined as having textbook multigrid efficiency (TME) if the solutions to the governing system of equations are attained in a computational work that is a small (less than 10) multiple of the operation count in one target-grid residual evaluation. The way to achieve this efficiency is the distributed relaxation approach. TME solvers employing distributed relaxation have already been demonstrated for nonconservative formulations of high-Reynolds-number viscous incompressible and subsonic compressible flow regimes. The purpose of this paper is to provide foundations for applications of distributed relaxation to conservative discretizations. A direct correspondence between the primitive variable interpolations for calculating fluxes in conservative finite-volume discretizations and stencils of the discretized derivatives in the nonconservative formulation has been established. Based on this correspondence, one can arrive at a conservative discretization which is very efficiently solved with a nonconservative relaxation scheme and this is demonstrated for conservative discretization of the quasi one-dimensional Euler equations. Formulations for both staggered and collocated grid arrangements are considered and extensions of the general procedure to multiple dimensions are discussed.

  12. Infrastructure for distributed enterprise simulation

    SciTech Connect

    Johnson, M.M.; Yoshimura, A.S.; Goldsby, M.E.

    1998-01-01

    Traditional discrete-event simulations employ an inherently sequential algorithm and are run on a single computer. However, the demands of many real-world problems exceed the capabilities of sequential simulation systems. Often the capacity of a computer`s primary memory limits the size of the models that can be handled, and in some cases parallel execution on multiple processors could significantly reduce the simulation time. This paper describes the development of an Infrastructure for Distributed Enterprise Simulation (IDES) - a large-scale portable parallel simulation framework developed to support Sandia National Laboratories` mission in stockpile stewardship. IDES is based on the Breathing-Time-Buckets synchronization protocol, and maps a message-based model of distributed computing onto an object-oriented programming model. IDES is portable across heterogeneous computing architectures, including single-processor systems, networks of workstations and multi-processor computers with shared or distributed memory. The system provides a simple and sufficient application programming interface that can be used by scientists to quickly model large-scale, complex enterprise systems. In the background and without involving the user, IDES is capable of making dynamic use of idle processing power available throughout the enterprise network. 16 refs., 14 figs.

  13. Distributed Virtual System (DIVIRS) project

    NASA Technical Reports Server (NTRS)

    Schorr, Herbert; Neuman, B. Clifford

    1993-01-01

    As outlined in the continuation proposal 92-ISI-50R (revised) on NASA cooperative agreement NCC 2-539, the investigators are developing software, including a system manager and a job manager, that will manage available resources and that will enable programmers to develop and execute parallel applications in terms of a virtual configuration of processors, hiding the mapping to physical nodes; developing communications routines that support the abstractions implemented; continuing the development of file and information systems based on the Virtual System Model; and incorporating appropriate security measures to allow the mechanisms developed to be used on an open network. The goal throughout the work is to provide a uniform model that can be applied to both parallel and distributed systems. The authors believe that multiprocessor systems should exist in the context of distributed systems, allowing them to be more easily shared by those that need them. The work provides the mechanisms through which nodes on multiprocessors are allocated to jobs running within the distributed system and the mechanisms through which files needed by those jobs can be located and accessed.

  14. Distributed Virtual System (DIVIRS) Project

    NASA Technical Reports Server (NTRS)

    Schorr, Herbert; Neuman, B. Clifford

    1993-01-01

    As outlined in our continuation proposal 92-ISI-50R (revised) on contract NCC 2-539, we are (1) developing software, including a system manager and a job manager, that will manage available resources and that will enable programmers to program parallel applications in terms of a virtual configuration of processors, hiding the mapping to physical nodes; (2) developing communications routines that support the abstractions implemented in item one; (3) continuing the development of file and information systems based on the virtual system model; and (4) incorporating appropriate security measures to allow the mechanisms developed in items 1 through 3 to be used on an open network. The goal throughout our work is to provide a uniform model that can be applied to both parallel and distributed systems. We believe that multiprocessor systems should exist in the context of distributed systems, allowing them to be more easily shared by those that need them. Our work provides the mechanisms through which nodes on multiprocessors are allocated to jobs running within the distributed system and the mechanisms through which files needed by those jobs can be located and accessed.

  15. DIstributed VIRtual System (DIVIRS) project

    NASA Technical Reports Server (NTRS)

    Schorr, Herbert; Neuman, Clifford B.

    1995-01-01

    As outlined in our continuation proposal 92-ISI-50R (revised) on NASA cooperative agreement NCC2-539, we are (1) developing software, including a system manager and a job manager, that will manage available resources and that will enable programmers to develop and execute parallel applications in terms of a virtual configuration of processors, hiding the mapping to physical nodes; (2) developing communications routines that support the abstractions implemented in item one; (3) continuing the development of file and information systems based on the Virtual System Model; and (4) incorporating appropriate security measures to allow the mechanisms developed in items 1 through 3 to be used on an open network. The goal throughout our work is to provide a uniform model that can be applied to both parallel and distributed systems. We believe that multiprocessor systems should exist in the context of distributed systems, allowing them to be more easily shared by those that need them. Our work provides the mechanisms through which nodes on multiprocessors are allocated to jobs running within the distributed system and the mechanisms through which files needed by those jobs can be located and accessed.

  16. DIstributed VIRtual System (DIVIRS) project

    NASA Technical Reports Server (NTRS)

    Schorr, Herbert; Neuman, B. Clifford

    1994-01-01

    As outlined in our continuation proposal 92-ISI-. OR (revised) on NASA cooperative agreement NCC2-539, we are (1) developing software, including a system manager and a job manager, that will manage available resources and that will enable programmers to develop and execute parallel applications in terms of a virtual configuration of processors, hiding the mapping to physical nodes; (2) developing communications routines that support the abstractions implemented in item one; (3) continuing the development of file and information systems based on the Virtual System Model; and (4) incorporating appropriate security measures to allow the mechanisms developed in items 1 through 3 to be used on an open network. The goal throughout our work is to provide a uniform model that can be applied to both parallel and distributed systems. We believe that multiprocessor systems should exist in the context of distributed systems, allowing them to be more easily shared by those that need them. Our work provides the mechanisms through which nodes on multiprocessors are allocated to jobs running within the distributed system and the mechanisms through which files needed by those jobs can be located and accessed.

  17. Energy conservation in electric distribution

    SciTech Connect

    Lee, Chong-Jin

    1994-12-31

    This paper discusses the potential for energy and power savings that exist in electric power delivery systems. These savings translate into significant financial and environmental benefits for electricity producers and consumers as well as for society in general. AlliedSignal`s knowledge and perspectives on this topic are the result of discussions with hundreds of utility executives, government officials and other industry experts over the past decade in conjunction with marketing our Amorphous Metal technology for electric distribution transformers. Amorphous metal is a technology developed by AlliedSignal that significantly reduces the energy lost in electric distribution transformers at an incremental cost of just a few cents per kilo-Watt-hour. The purpose of this paper is to discuss: Amorphous Metal Alloy Technology; Energy Savings Opportunity; The Industrial Barriers and Remedies; Worldwide Demand; and A Low Risk Strategy. I wish this presentation will help KEPCO achieve their stated aims of ensuring sound development of the national economy and enhancement of public life through the economic and stable supply of electric power. AlliedSignal Korea Ltd. in conjunction with AlliedSignal Amorphous Metals in the U.S. are here to work with KEPCO, transformer manufacturers, industry, and government agencies to achieve greater efficiency in power distribution.

  18. Preliminary Iron Distribution on Vesta

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, David W.; Mittlefehldt, David W.

    2013-01-01

    The distribution of iron on the surface of the asteroid Vesta was investigated using Dawn's Gamma Ray and Neutron Detector (GRaND) [1,2]. Iron varies predictably with rock type for the howardite, eucrite, and diogenite (HED) meteorites, thought to be representative of Vesta. The abundance of Fe in howardites ranges from about 12 to 15 wt.%. Basaltic eucrites have the highest abundance, whereas, lower crustal and upper mantle materials (cumulate eucrites and diogenites) have the lowest, and howardites are intermediate [3]. We have completed a mapping study of 7.6 MeV gamma rays produced by neutron capture by Fe as measured by the bismuth germanate (BGO) detector of GRaND [1]. The procedures to determine Fe counting rates are presented in detail here, along with a preliminary distribution map, constituting the necessary initial step to quantification of Fe abundances. We find that the global distribution of Fe counting rates is generally consistent with independent mineralogical and compositional inferences obtained by other instruments on Dawn such as measurements of pyroxene absorption bands by the Visual and Infrared Spectrometer (VIR) [4] and Framing Camera (FC) [5] and neutron absorption measurements by GRaND [6].

  19. Jefferson Lab's Distributed Data Acquisition

    SciTech Connect

    Trent Allison; Thomas Powers

    2006-05-01

    Jefferson Lab's Continuous Electron Beam Accelerator Facility (CEBAF) occasionally experiences fast intermittent beam instabilities that are difficult to isolate and result in downtime. The Distributed Data Acquisition (Dist DAQ) system is being developed to detect and quickly locate such instabilities. It will consist of multiple Ethernet based data acquisition chassis distributed throughout the seven-eights of a mile CEBAF site. Each chassis will monitor various control system signals that are only available locally and/or monitored by systems with small bandwidths that cannot identify fast transients. The chassis will collect data at rates up to 40 Msps in circular buffers that can be frozen and unrolled after an event trigger. These triggers will be derived from signals such as periodic timers or accelerator faults and be distributed via a custom fiber optic event trigger network. This triggering scheme will allow all the data acquisition chassis to be triggered simultaneously and provide a snapshot of relevant CEBAF control signals. The data will then be automatically analyzed for frequency content and transients to determine if and where instabilities exist.

  20. Review of data analysis procedures for the ATS-6 millimeter wave experiment

    NASA Technical Reports Server (NTRS)

    Meneghini, R.

    1975-01-01

    Predictions of satellite downlink attenuation through the use of ground based measurements form a substantial part of the ATS-6 millimeter wave experiment (MWE). At the downlink frequencies (20 and 30 GHz), the major causes of attenuation are the density and the size distribution of rain drops along the propagation path. Ground station data, which include radar and rain gauge records, measure quantities related to the meteorological parameters of interest and thereby provide a prediction of downlink attenuation with which the measured attenuation can be compared. The calibration and data analysis procedures used in the MWE are reviewed with the object of improving the accuracy of such ground based predictions.

  1. Problem solving in a distributed environment

    NASA Technical Reports Server (NTRS)

    Rashid, R. F.

    1980-01-01

    Distributed problem solving is anayzed as a blend of two disciplines: (1) problem solving and ai; and (2) distributed systems (monitoring). It may be necessary to distribute because the application itself is one of managing distributed resources (e.g., distributed sensor net) and communication delays preclude centralized processing, or it may be desirable to distribute because a single computational engine may not satisfy the needs of a given task. In addition, considerations of reliability may dictate distribution. Examples of multi-process language environment are given.

  2. Invariant distributions on compact homogeneous spaces

    SciTech Connect

    Gorbatsevich, V V

    2013-12-31

    In this paper, we study distributions on compact homogeneous spaces, including invariant distributions and also distributions admitting a sub-Riemannian structure. We first consider distributions of dimension 1 and 2 on compact homogeneous spaces. After this, we study the cases of compact homogeneous spaces of dimension 2, 3, and 4 in detail. Invariant distributions on simply connected compact homogeneous spaces are also treated. Bibliography: 18 titles.

  3. A distributed clients/distributed servers model for STARCAT

    NASA Technical Reports Server (NTRS)

    Pirenne, B.; Albrecht, M. A.; Durand, D.; Gaudet, S.

    1992-01-01

    STARCAT, the Space Telescope ARchive and CATalogue user interface has been along for a number of years already. During this time it has been enhanced and augmented in a number of different fields. This time, we would like to dwell on a new capability allowing geographically distributed user interfaces to connect to geographically distributed data servers. This new concept permits users anywhere on the internet running STARCAT on their local hardware to access e.g., whichever of the 3 existing HST archive sites is available, or get information on the CFHT archive through a transparent connection to the CADC in BC or to get the La Silla weather by connecting to the ESO database in Munich during the same session. Similarly PreView (or quick look) images and spectra will also flow directly to the user from wherever it is available. Moving towards an 'X'-based STARCAT is another goal being pursued: a graphic/image server and a help/doc server are currently being added to it. They should further enhance the user independence and access transparency.

  4. Triple junction distributions in polycrystals

    SciTech Connect

    King, W.E.; Kumar, M.; Schwartz, A.J.

    1999-07-01

    Recently, it has been demonstrated that some material properties can be enhanced by grain boundary engineering, i.e., the systematic modifications in the topology of the microstructure through thermomechanical processing. Experimental observations have shown that the microstructural parameter likely responsible for improved properties is the grain boundary character distribution (GBCD). It has been suggested that improvements in the fractions of special boundaries as defined by the coincident site lattice model (1) are necessary, but not fully sufficient to cause property improvements. For example, it has been observed that cracks propagating along interconnected networks of random grain boundaries can be arrested (2) when intersecting a triple junction where the remaining two pathways are special boundaries. Therefore, it is of interest to characterize microstructures in terms of the distributions of triple junction types. A simple method to describe a triple junction is by the types of grain boundaries intersecting at that junction [special vs. random, as described by the coincident site lattice (CSL) model]. The distribution of 0-CSL, 1-CSL, 2-CSL and 3-CSL triple junctions in the microstructure can then be plotted as a function of the fraction of special boundaries. Such data has been collected using orientation-imaging microscopy (OIM) (3--5) for oxygen-free-electronic (ofe)-Cu and Inconel 600 over a range of special fraction of grain boundaries. These results have been compared with theoretical models considering isolated triple junctions and invoking the {Sigma}-product rule (6) where {Sigma} is the inverse density of coincident lattice sites (7).

  5. Adaptive reconfigurable distributed sensor architecture

    NASA Astrophysics Data System (ADS)

    Akey, Mark L.

    1997-07-01

    The infancy of unattended ground based sensors is quickly coming to an end with the arrival of on-board GPS, networking, and multiple sensing capabilities. Unfortunately, their use is only first-order at best: GPS assists with sensor report registration; networks push sensor reports back to the warfighter and forwards control information to the sensors; multispectral sensing is a preset, pre-deployment consideration; and the scalability of large sensor networks is questionable. Current architectures provide little synergy among or within the sensors either before or after deployment, and do not map well to the tactical user's organizational structures and constraints. A new distributed sensor architecture is defined which moves well beyond single sensor, single task architectures. Advantages include: (1) automatic mapping of tactical direction to multiple sensors' tasks; (2) decentralized, distributed management of sensor resources and tasks; (3) software reconfiguration of deployed sensors; (4) network scalability and flexibility to meet the constraints of tactical deployments, and traditional combat organizations and hierarchies; and (5) adaptability to new battlefield communication paradigms such as BADD (Battlefield Analysis and Data Dissemination). The architecture is supported in two areas: a recursive, structural definition of resource configuration and management via loose associations; and a hybridization of intelligent software agents with tele- programming capabilities. The distributed sensor architecture is examined within the context of air-deployed ground sensors with acoustic, communication direction finding, and infra-red capabilities. Advantages and disadvantages of the architecture are examined. Consideration is given to extended sensor life (up to 6 months), post-deployment sensor reconfiguration, limited on- board sensor resources (processor and memory), and bandwidth. It is shown that technical tasking of the sensor suite can be automatically

  6. Environmental distribution of prokaryotic taxa

    PubMed Central

    2010-01-01

    Background The increasing availability of gene sequences of prokaryotic species in samples extracted from all kind of locations allows addressing the study of the influence of environmental patterns in prokaryotic biodiversity. We present a comprehensive study to address the potential existence of environmental preferences of prokaryotic taxa and the commonness of the specialist and generalist strategies. We also assessed the most significant environmental factors shaping the environmental distribution of taxa. Results We used 16S rDNA sequences from 3,502 sampling experiments in natural and artificial sources. These sequences were taxonomically assigned, and the corresponding samples were also classified into a hierarchical classification of environments. We used several statistical methods to analyze the environmental distribution of taxa. Our results indicate that environmental specificity is not very common at the higher taxonomic levels (phylum to family), but emerges at lower taxonomic levels (genus and species). The most selective environmental characteristics are those of animal tissues and thermal locations. Salinity is another very important factor for constraining prokaryotic diversity. On the other hand, soil and freshwater habitats are the less restrictive environments, harboring the largest number of prokaryotic taxa. All information on taxa, samples and environments is provided at the envDB online database, http://metagenomics.uv.es/envDB. Conclusions This is, as far as we know, the most comprehensive assessment of the distribution and diversity of prokaryotic taxa and their associations with different environments. Our data indicate that we are still far from characterizing prokaryotic diversity in any environment, except, perhaps, for human tissues such as the oral cavity and the vagina. PMID:20307274

  7. The pulsar spectral index distribution

    NASA Astrophysics Data System (ADS)

    Bates, S. D.; Lorimer, D. R.; Verbiest, J. P. W.

    2013-05-01

    The flux-density spectra of radio pulsars are known to be steep and, to first order, described by a power-law relationship of the form Sν ∝ να, where Sν is the flux density at some frequency ν and α is the spectral index. Although measurements of α have been made over the years for several hundred pulsars, a study of the intrinsic distribution of pulsar spectra has not been carried out. From the result of pulsar surveys carried out at three different radio frequencies, we use population synthesis techniques and a likelihood analysis to deduce what underlying spectral index distribution is required to replicate the results of these surveys. We find that in general the results of the surveys can be modelled by a Gaussian distribution of spectral indices with a mean of -1.4 and unit standard deviation. We also consider the impact of the so-called gigahertz-peaked spectrum pulsars proposed by Kijak et al. The fraction of peaked-spectrum sources in the population with any significant turnover at low frequencies appears to be at most 10 per cent. We demonstrate that high-frequency (>2 GHz) surveys preferentially select flatter spectrum pulsars and the converse is true for lower frequency (<1 GHz) surveys. This implies that any correlations between α and other pulsar parameters (for example age or magnetic field) need to carefully account for selection biases in pulsar surveys. We also expect that many known pulsars which have been detected at high frequencies will have shallow, or positive, spectral indices. The majority of pulsars do not have recorded flux density measurements over a wide frequency range, making it impossible to constrain their spectral shapes. We also suggest that such measurements would allow an improved description of any populations of pulsars with `non-standard' spectra. Further refinements to this picture will soon be possible from the results of surveys with the Green Bank Telescope and LOFAR.

  8. Distributed GPU Computing in GIScience

    NASA Astrophysics Data System (ADS)

    Jiang, Y.; Yang, C.; Huang, Q.; Li, J.; Sun, M.

    2013-12-01

    Geoscientists strived to discover potential principles and patterns hidden inside ever-growing Big Data for scientific discoveries. To better achieve this objective, more capable computing resources are required to process, analyze and visualize Big Data (Ferreira et al., 2003; Li et al., 2013). Current CPU-based computing techniques cannot promptly meet the computing challenges caused by increasing amount of datasets from different domains, such as social media, earth observation, environmental sensing (Li et al., 2013). Meanwhile CPU-based computing resources structured as cluster or supercomputer is costly. In the past several years with GPU-based technology matured in both the capability and performance, GPU-based computing has emerged as a new computing paradigm. Compare to traditional computing microprocessor, the modern GPU, as a compelling alternative microprocessor, has outstanding high parallel processing capability with cost-effectiveness and efficiency(Owens et al., 2008), although it is initially designed for graphical rendering in visualization pipe. This presentation reports a distributed GPU computing framework for integrating GPU-based computing within distributed environment. Within this framework, 1) for each single computer, computing resources of both GPU-based and CPU-based can be fully utilized to improve the performance of visualizing and processing Big Data; 2) within a network environment, a variety of computers can be used to build up a virtual super computer to support CPU-based and GPU-based computing in distributed computing environment; 3) GPUs, as a specific graphic targeted device, are used to greatly improve the rendering efficiency in distributed geo-visualization, especially for 3D/4D visualization. Key words: Geovisualization, GIScience, Spatiotemporal Studies Reference : 1. Ferreira de Oliveira, M. C., & Levkowitz, H. (2003). From visual data exploration to visual data mining: A survey. Visualization and Computer Graphics, IEEE

  9. Distributed optimization system and method

    DOEpatents

    Hurtado, John E.; Dohrmann, Clark R.; Robinett, III, Rush D.

    2003-06-10

    A search system and method for controlling multiple agents to optimize an objective using distributed sensing and cooperative control. The search agent can be one or more physical agents, such as a robot, and can be software agents for searching cyberspace. The objective can be: chemical sources, temperature sources, radiation sources, light sources, evaders, trespassers, explosive sources, time dependent sources, time independent sources, function surfaces, maximization points, minimization points, and optimal control of a system such as a communication system, an economy, a crane, and a multi-processor computer.

  10. Ubiquitous distributed objects with CORBA.

    PubMed

    Achard, F; Barillot, E

    1997-01-01

    Database interoperation is becoming a bottleneck for the research community in biology. In this paper, we first discuss the question of interoperability and give a brief overview of CORBA. Then, an example is explained in some detail: a simple but realistic data bank of STSs is implemented. The Object Request Broker is the media for communication between an object server (the data bank) and a client (possibly a genome center). Since CORBA enables easy development of networked applications, we meant this paper to provide an incentive for the bioinformatics community to develop distributed objects.

  11. Synchronous Sampling for Distributed Experiments

    NASA Astrophysics Data System (ADS)

    Wittkamp, M.; Ettl, J.

    2015-09-01

    Sounding Rocket payloads, especially for atmospheric research, often consists of several independent sensors or experiments with different objectives. The data of these sensors can be combined in the post processing to improve the scientific results of the flight. One major requirement for this data-correlation is a common timeline for the measurements of the distributed experiments. Within this paper we present two ways to achieve absolute timing for asynchronously working experiments. The synchronization process is using the Global Positioning System (GPS) and a standard serial communication protocol for transport of timestamps and flight-states.

  12. The CJ12 parton distributions

    SciTech Connect

    Accardi, Alberto; Owens, Jeff F.

    2013-07-01

    Three new sets of next-to-leading order parton distribution functions (PDFs) are presented, determined by global fits to a wide variety of data for hard scattering processes. The analysis includes target mass and higher twist corrections needed for the description of deep-inelastic scattering data at large x and low Q^2, and nuclear corrections for deuterium targets. The PDF sets correspond to three different models for the nuclear effects, and provide a more realistic uncertainty range for the d quark PDF compared with previous fits. Applications to weak boson production at colliders are also discussed.

  13. Distributions of nonsupersymmetric flux vacua

    NASA Astrophysics Data System (ADS)

    Denef, Frederik; Douglas, Michael R.

    2005-03-01

    We continue the study of the distribution of nonsupersymmetric flux vacua in IIb string theory compactified on Calabi-Yau manifolds, as in hep-th/0404116. We show that the basic structure of this problem is that of finding eigenvectors of the matrix of second derivatives of the superpotential, and that many features of the results are determined by features of the generic ensemble of such matrices, the CI ensemble of Altland and Zirnbauer originating in mesoscopic physics. We study some simple examples in detail, exhibiting various factors which can favor low or high scale supersymmetry breaking.

  14. Heat distribution by natural convection

    SciTech Connect

    Balcomb, J.D.

    1985-01-01

    Natural convection can provide adequate heat distribution in many situtations that arise in buildings. This is appropriate, for example, in passive solar buildings where some rooms tend to be more strongly solar heated than others or to reduce the number of heating units required in a building. Natural airflow and heat transport through doorways and other internal building apertures is predictable and can be accounted for in the design. The nature of natural convection is described, and a design chart is presented appropriate to a simple, single-doorway situation. Natural convective loops that can occur in buildings are described and a few design guidelines are presented.

  15. Distributed Accounting on the Grid

    NASA Technical Reports Server (NTRS)

    Thigpen, William; Hacker, Thomas J.; McGinnis, Laura F.; Athey, Brian D.

    2001-01-01

    By the late 1990s, the Internet was adequately equipped to move vast amounts of data between HPC (High Performance Computing) systems, and efforts were initiated to link together the national infrastructure of high performance computational and data storage resources together into a general computational utility 'grid', analogous to the national electrical power grid infrastructure. The purpose of the Computational grid is to provide dependable, consistent, pervasive, and inexpensive access to computational resources for the computing community in the form of a computing utility. This paper presents a fully distributed view of Grid usage accounting and a methodology for allocating Grid computational resources for use on a Grid computing system.

  16. Workshop on momentum distributions: Summary

    SciTech Connect

    Simmons, R.O.

    1988-01-01

    This has been an extraordinary Workshop touching many branches of physics. The Workshop has treated momentum distributions in fluid and solid condensed matter, in nuclei, and in electronic systems. Both theoretical and experimental concepts and methods have been considered in all these branches. A variety of specific illustrations and applications in physical systems have been presented. One finds that some common unifying themes emerge. One finds, also, that some examples are available to illustrate where one branch is more mature than others and to contrast where expectations for future progress may be most encouraged. 6 refs., 2 figs.

  17. Distributed Control with Collective Intelligence

    NASA Technical Reports Server (NTRS)

    Wolpert, David H.; Wheeler, Kevin R.; Tumer, Kagan

    1998-01-01

    We consider systems of interacting reinforcement learning (RL) algorithms that do not work at cross purposes , in that their collective behavior maximizes a global utility function. We call such systems COllective INtelligences (COINs). We present the theory of designing COINs. Then we present experiments validating that theory in the context of two distributed control problems: We show that COINs perform near-optimally in a difficult variant of Arthur's bar problem [Arthur] (and in particular avoid the tragedy of the commons for that problem), and we also illustrate optimal performance in the master-slave problem.

  18. Distributed wireless quantum communication networks

    NASA Astrophysics Data System (ADS)

    Yu, Xu-Tao; Xu, Jin; Zhang, Zai-Chen

    2013-09-01

    The distributed wireless quantum communication network (DWQCN) has a distributed network topology and transmits information by quantum states. In this paper, we present the concept of the DWQCN and propose a system scheme to transfer quantum states in the DWQCN. The system scheme for transmitting information between any two nodes in the DWQCN includes a routing protocol and a scheme for transferring quantum states. The routing protocol is on-demand and the routing metric is selected based on the number of entangled particle pairs. After setting up a route, quantum teleportation and entanglement swapping are used for transferring quantum states. Entanglement swapping is achieved along with the process of routing set up and the acknowledgment packet transmission. The measurement results of each entanglement swapping are piggybacked with route reply packets or acknowledgment packets. After entanglement swapping, a direct quantum link between source and destination is set up and quantum states are transferred by quantum teleportation. Adopting this scheme, the measurement results of entanglement swapping do not need to be transmitted specially, which decreases the wireless transmission cost and transmission delay.

  19. Distributed nestmate recognition in ants

    PubMed Central

    Esponda, Fernando; Gordon, Deborah M.

    2015-01-01

    We propose a distributed model of nestmate recognition, analogous to the one used by the vertebrate immune system, in which colony response results from the diverse reactions of many ants. The model describes how individual behaviour produces colony response to non-nestmates. No single ant knows the odour identity of the colony. Instead, colony identity is defined collectively by all the ants in the colony. Each ant responds to the odour of other ants by reference to its own unique decision boundary, which is a result of its experience of encounters with other ants. Each ant thus recognizes a particular set of chemical profiles as being those of non-nestmates. This model predicts, as experimental results have shown, that the outcome of behavioural assays is likely to be variable, that it depends on the number of ants tested, that response to non-nestmates changes over time and that it changes in response to the experience of individual ants. A distributed system allows a colony to identify non-nestmates without requiring that all individuals have the same complete information and helps to facilitate the tracking of changes in cuticular hydrocarbon profiles, because only a subset of ants must respond to provide an adequate response. PMID:25833853

  20. Agent Communications using Distributed Metaobjects

    SciTech Connect

    Goldsmith, Steven Y.; Spires, Shannon V.

    1999-06-10

    There are currently two proposed standards for agent communication languages, namely, KQML (Finin, Lobrou, and Mayfield 1994) and the FIPA ACL. Neither standard has yet achieved primacy, and neither has been evaluated extensively in an open environment such as the Internet. It seems prudent therefore to design a general-purpose agent communications facility for new agent architectures that is flexible yet provides an architecture that accepts many different specializations. In this paper we exhibit the salient features of an agent communications architecture based on distributed metaobjects. This architecture captures design commitments at a metaobject level, leaving the base-level design and implementation up to the agent developer. The scope of the metamodel is broad enough to accommodate many different communication protocols, interaction protocols, and knowledge sharing regimes through extensions to the metaobject framework. We conclude that with a powerful distributed object substrate that supports metaobject communications, a general framework can be developed that will effectively enable different approaches to agent communications in the same agent system. We have implemented a KQML-based communications protocol and have several special-purpose interaction protocols under development.

  1. Plankton distribution and ocean dispersal.

    PubMed

    McManus, Margaret Anne; Woodson, C Brock

    2012-03-15

    Plankton are small organisms that dwell in oceans, seas and bodies of fresh water. In this review, we discuss life in the plankton, which involves a balance between the behavioral capabilities of the organism and the characteristics and movement of the water that surrounds it. In order to consider this balance, we discuss how plankton interact with their environment across a range of scales - from the smallest viruses and bacteria to larger phytoplankton and zooplankton. We find that the larger scale distributions of plankton, observed in coastal waters, along continental shelves and in ocean basins, are highly dependent upon the smaller scale interactions between the individual organism and its environment. Further, we discuss how larger scale organism distributions may affect the transport and/or retention of plankton in the ocean environment. The research reviewed here provides a mechanistic understanding of how organism behavior in response to the physical environment produces planktonic aggregations, which has a direct impact on the way marine ecosystems function. PMID:22357594

  2. Analyzing ion distributions around DNA.

    PubMed

    Lavery, Richard; Maddocks, John H; Pasi, Marco; Zakrzewska, Krystyna

    2014-07-01

    We present a new method for analyzing ion, or molecule, distributions around helical nucleic acids and illustrate the approach by analyzing data derived from molecular dynamics simulations. The analysis is based on the use of curvilinear helicoidal coordinates and leads to highly localized ion densities compared to those obtained by simply superposing molecular dynamics snapshots in Cartesian space. The results identify highly populated and sequence-dependent regions where ions strongly interact with the nucleic and are coupled to its conformational fluctuations. The data from this approach is presented as ion populations or ion densities (in units of molarity) and can be analyzed in radial, angular and longitudinal coordinates using 1D or 2D graphics. It is also possible to regenerate 3D densities in Cartesian space. This approach makes it easy to understand and compare ion distributions and also allows the calculation of average ion populations in any desired zone surrounding a nucleic acid without requiring references to its constituent atoms. The method is illustrated using microsecond molecular dynamics simulations for two different DNA oligomers in the presence of 0.15 M potassium chloride. We discuss the results in terms of convergence, sequence-specific ion binding and coupling with DNA conformation. PMID:24906882

  3. Analyzing ion distributions around DNA

    PubMed Central

    Lavery, Richard; Maddocks, John H.; Pasi, Marco; Zakrzewska, Krystyna

    2014-01-01

    We present a new method for analyzing ion, or molecule, distributions around helical nucleic acids and illustrate the approach by analyzing data derived from molecular dynamics simulations. The analysis is based on the use of curvilinear helicoidal coordinates and leads to highly localized ion densities compared to those obtained by simply superposing molecular dynamics snapshots in Cartesian space. The results identify highly populated and sequence-dependent regions where ions strongly interact with the nucleic and are coupled to its conformational fluctuations. The data from this approach is presented as ion populations or ion densities (in units of molarity) and can be analyzed in radial, angular and longitudinal coordinates using 1D or 2D graphics. It is also possible to regenerate 3D densities in Cartesian space. This approach makes it easy to understand and compare ion distributions and also allows the calculation of average ion populations in any desired zone surrounding a nucleic acid without requiring references to its constituent atoms. The method is illustrated using microsecond molecular dynamics simulations for two different DNA oligomers in the presence of 0.15 M potassium chloride. We discuss the results in terms of convergence, sequence-specific ion binding and coupling with DNA conformation. PMID:24906882

  4. Overlapping clusters for distributed computation.

    SciTech Connect

    Mirrokni, Vahab; Andersen, Reid; Gleich, David F.

    2010-11-01

    Scalable, distributed algorithms must address communication problems. We investigate overlapping clusters, or vertex partitions that intersect, for graph computations. This setup stores more of the graph than required but then affords the ease of implementation of vertex partitioned algorithms. Our hope is that this technique allows us to reduce communication in a computation on a distributed graph. The motivation above draws on recent work in communication avoiding algorithms. Mohiyuddin et al. (SC09) design a matrix-powers kernel that gives rise to an overlapping partition. Fritzsche et al. (CSC2009) develop an overlapping clustering for a Schwarz method. Both techniques extend an initial partitioning with overlap. Our procedure generates overlap directly. Indeed, Schwarz methods are commonly used to capitalize on overlap. Elsewhere, overlapping communities (Ahn et al, Nature 2009; Mishra et al. WAW2007) are now a popular model of structure in social networks. These have long been studied in statistics (Cole and Wishart, CompJ 1970). We present two types of results: (i) an estimated swapping probability {rho}{infinity}; and (ii) the communication volume of a parallel PageRank solution (link-following {alpha} = 0.85) using an additive Schwarz method. The volume ratio is the amount of extra storage for the overlap (2 means we store the graph twice). Below, as the ratio increases, the swapping probability and PageRank communication volume decreases.

  5. Distributed computing at the SSCL

    SciTech Connect

    Cormell, L.; White, R.

    1993-05-01

    The rapid increase in the availability of high performance, cost- effective RISC/UNIX workstations has been both a blessing and a curse. The blessing of having extremely powerful computing engines available on the desk top is well-known to many users. The user has tremendous freedom, flexibility, and control of his environment. That freedom can, however, become the curse of distributed computing. The user must become a system manager to some extent, he must worry about backups, maintenance, upgrades, etc. Traditionally these activities have been the responsibility of a central computing group. The central computing group, however, may find that it can no linger provide all of the traditional services. With the plethora of workstations now found on so many desktops throughout the entire campus or lab, the central computing group may be swamped by support requests. This talk will address several of these computer support and management issues by discussing the approach taken at the Superconducting Super Collider Laboratory. In addition, a brief review of the future directions of commercial products for distributed computing and management will be given.

  6. Distributed nestmate recognition in ants.

    PubMed

    Esponda, Fernando; Gordon, Deborah M

    2015-05-01

    We propose a distributed model of nestmate recognition, analogous to the one used by the vertebrate immune system, in which colony response results from the diverse reactions of many ants. The model describes how individual behaviour produces colony response to non-nestmates. No single ant knows the odour identity of the colony. Instead, colony identity is defined collectively by all the ants in the colony. Each ant responds to the odour of other ants by reference to its own unique decision boundary, which is a result of its experience of encounters with other ants. Each ant thus recognizes a particular set of chemical profiles as being those of non-nestmates. This model predicts, as experimental results have shown, that the outcome of behavioural assays is likely to be variable, that it depends on the number of ants tested, that response to non-nestmates changes over time and that it changes in response to the experience of individual ants. A distributed system allows a colony to identify non-nestmates without requiring that all individuals have the same complete information and helps to facilitate the tracking of changes in cuticular hydrocarbon profiles, because only a subset of ants must respond to provide an adequate response.

  7. Countercurrent distribution of biological cells

    NASA Technical Reports Server (NTRS)

    1982-01-01

    It is known that the addition of phosphate buffer to two polymer aqueous phase systems has a strong effect on the partition behavior of cells and other particles in such mixtures. The addition of sodium phosphate to aqueous poly(ethylene glycol) dextran phase systems causes a concentration-dependent shift in binodial on the phase diagram, progressively lowering the critical conditions for phase separation as the phosphate concentration is increased. Sodium chloride produces no significant shift in the critical point relative to the salt-free case. Accurate determinations of the phase diagram require measurements of the density of the phases; data is presented which allows this parameter to be calculated from polarimetric measurements of the dextran concentrations of both phases. Increasing polymer concentrations in the phase systems produce increasing preference of the phosphate for the dextran-rich bottom phase. Equilibrium dialysis experiments showed that poly(ethylene glycol) effectively rejected phosphate, and to a lesser extent chloride, but that dextran had little effect on the distribution of either salt. Increasing ionic strength via addition of 0.15 M NaCl to phase systems containing 0.01 M phosphate produces an increased concentration of phosphate ions in the bottom dextran-rich phase, the expected effect in this type of Donnan distribution.

  8. The genetics of fat distribution.

    PubMed

    Schleinitz, Dorit; Böttcher, Yvonne; Blüher, Matthias; Kovacs, Peter

    2014-07-01

    Fat stored in visceral depots makes obese individuals more prone to complications than subcutaneous fat. There is good evidence that body fat distribution (FD) is controlled by genetic factors. WHR, a surrogate measure of FD, shows significant heritability of up to ∼60%, even after adjusting for BMI. Genetic variants have been linked to various forms of altered FD such as lipodystrophies; however, the polygenic background of visceral obesity has only been sparsely investigated in the past. Recent genome-wide association studies (GWAS) for measures of FD revealed numerous loci harbouring genes potentially regulating FD. In addition, genes with fat depot-specific expression patterns (in particular subcutaneous vs visceral adipose tissue) provide plausible candidate genes involved in the regulation of FD. Many of these genes are differentially expressed in various fat compartments and correlate with obesity-related traits, thus further supporting their role as potential mediators of metabolic alterations associated with a distinct FD. Finally, developmental genes may at a very early stage determine specific FD in later life. Indeed, genes such as TBX15 not only manifest differential expression in various fat depots, but also correlate with obesity and related traits. Moreover, recent GWAS identified several polymorphisms in developmental genes (including TBX15, HOXC13, RSPO3 and CPEB4) strongly associated with FD. More accurate methods, including cardiometabolic imaging, for assessment of FD are needed to promote our understanding in this field, where the main focus is now to unravel the yet unknown biological function of these novel 'fat distribution genes'.

  9. Detector decoy quantum key distribution

    NASA Astrophysics Data System (ADS)

    Moroder, Tobias; Curty, Marcos; Lütkenhaus, Norbert

    2009-04-01

    Photon number resolving detectors can enhance the performance of many practical quantum cryptographic setups. In this paper, we employ a simple method to estimate the statistics provided by such a photon number resolving detector using only a threshold detector together with a variable attenuator. This idea is similar in spirit to that of the decoy state technique, and is especially suited to those scenarios where only a few parameters of the photon number statistics of the incoming signals have to be estimated. As an illustration of the potential applicability of the method in quantum communication protocols, we use it to prove security of an entanglement-based quantum key distribution scheme with an untrusted source without the need for a squash model and by solely using this extra idea. In this sense, this detector decoy method can be seen as a different conceptual approach to adapt a single-photon security proof to its physical, full optical implementation. We show that in this scenario, the legitimate users can now even discard the double click events from the raw key data without compromising the security of the scheme, and we present simulations on the performance of the BB84 and the 6-state quantum key distribution protocols.

  10. Evaluation of distributed computing tools

    SciTech Connect

    Stanberry, L.

    1992-10-28

    The original goal stated in the collaboration agreement from LCC`s perspective was ``to show that networking tools available in UNICOS perform well enough to meet the requirements of LCC customers.`` This translated into evaluating how easy it was to port ELROS over CRI`s ISO 2.0, which itself is a port of ISODE to the Cray. In addition we tested the interoperability of ELROS and ISO 2.0 programs running on the Cray, and communicating with each other, and with servers or clients running on other machines. To achieve these goals from LCC`s side, we ported ELROS to the Cray, and also obtained and installed a copy of the ISO 2.0 distribution from CRI. CRI`s goal for the collaboration was to evaluate the usability of ELROS. In particular, we were interested in their potential feedback on the use of ELROS in implementing ISO protocols--whether ELROS would be easter to use and perform better than other tools that form part of the standard ISODE system. To help achieve these goals for CRI, we provided them with a distribution tar file containing the ELROS system, once we had completed our port of ELROS to the Cray.

  11. Evaluation of distributed computing tools

    SciTech Connect

    Stanberry, L.

    1992-10-28

    The original goal stated in the collaboration agreement from LCC's perspective was to show that networking tools available in UNICOS perform well enough to meet the requirements of LCC customers.'' This translated into evaluating how easy it was to port ELROS over CRI's ISO 2.0, which itself is a port of ISODE to the Cray. In addition we tested the interoperability of ELROS and ISO 2.0 programs running on the Cray, and communicating with each other, and with servers or clients running on other machines. To achieve these goals from LCC's side, we ported ELROS to the Cray, and also obtained and installed a copy of the ISO 2.0 distribution from CRI. CRI's goal for the collaboration was to evaluate the usability of ELROS. In particular, we were interested in their potential feedback on the use of ELROS in implementing ISO protocols--whether ELROS would be easter to use and perform better than other tools that form part of the standard ISODE system. To help achieve these goals for CRI, we provided them with a distribution tar file containing the ELROS system, once we had completed our port of ELROS to the Cray.

  12. Distance distribution in configuration-model networks

    NASA Astrophysics Data System (ADS)

    Nitzan, Mor; Katzav, Eytan; Kühn, Reimer; Biham, Ofer

    2016-06-01

    We present analytical results for the distribution of shortest path lengths between random pairs of nodes in configuration model networks. The results, which are based on recursion equations, are shown to be in good agreement with numerical simulations for networks with degenerate, binomial, and power-law degree distributions. The mean, mode, and variance of the distribution of shortest path lengths are also evaluated. These results provide expressions for central measures and dispersion measures of the distribution of shortest path lengths in terms of moments of the degree distribution, illuminating the connection between the two distributions.

  13. Why the distribution of medical errors matters.

    PubMed

    McLean, Thomas R

    2015-07-01

    During the last decade, interventions to reduce the number of medical errors have been largely ineffective. Although it is widely assumed that medical errors follow a Gaussian distribution, they may actually follow a Power Rule distribution. This article presents the evidence in favor of a Power Rule distribution for medical errors and then examines the consequences of such a distribution for medical errors. As the distribution of medical errors has real-world implications, further research is needed to determine whether medical errors follow a Gaussian or Power Rule distribution.

  14. Distance distribution in configuration-model networks.

    PubMed

    Nitzan, Mor; Katzav, Eytan; Kühn, Reimer; Biham, Ofer

    2016-06-01

    We present analytical results for the distribution of shortest path lengths between random pairs of nodes in configuration model networks. The results, which are based on recursion equations, are shown to be in good agreement with numerical simulations for networks with degenerate, binomial, and power-law degree distributions. The mean, mode, and variance of the distribution of shortest path lengths are also evaluated. These results provide expressions for central measures and dispersion measures of the distribution of shortest path lengths in terms of moments of the degree distribution, illuminating the connection between the two distributions. PMID:27415282

  15. A distributed programming environment for Ada

    NASA Technical Reports Server (NTRS)

    Brennan, Peter; Mcdonnell, Tom; Mcfarland, Gregory; Timmins, Lawrence J.; Litke, John D.

    1986-01-01

    Despite considerable commercial exploitation of fault tolerance systems, significant and difficult research problems remain in such areas as fault detection and correction. A research project is described which constructs a distributed computing test bed for loosely coupled computers. The project is constructing a tool kit to support research into distributed control algorithms, including a distributed Ada compiler, distributed debugger, test harnesses, and environment monitors. The Ada compiler is being written in Ada and will implement distributed computing at the subsystem level. The design goal is to provide a variety of control mechanics for distributed programming while retaining total transparency at the code level.

  16. Water Distribution and Removal Model

    SciTech Connect

    Y. Deng; N. Chipman; E.L. Hardin

    2005-08-26

    The design of the Yucca Mountain high level radioactive waste repository depends on the performance of the engineered barrier system (EBS). To support the total system performance assessment (TSPA), the Engineered Barrier System Degradation, Flow, and Transport Process Model Report (EBS PMR) is developed to describe the thermal, mechanical, chemical, hydrological, biological, and radionuclide transport processes within the emplacement drifts, which includes the following major analysis/model reports (AMRs): (1) EBS Water Distribution and Removal (WD&R) Model; (2) EBS Physical and Chemical Environment (P&CE) Model; (3) EBS Radionuclide Transport (EBS RNT) Model; and (4) EBS Multiscale Thermohydrologic (TH) Model. Technical information, including data, analyses, models, software, and supporting documents will be provided to defend the applicability of these models for their intended purpose of evaluating the postclosure performance of the Yucca Mountain repository system. The WD&R model ARM is important to the site recommendation. Water distribution and removal represents one component of the overall EBS. Under some conditions, liquid water will seep into emplacement drifts through fractures in the host rock and move generally downward, potentially contacting waste packages. After waste packages are breached by corrosion, some of this seepage water will contact the waste, dissolve or suspend radionuclides, and ultimately carry radionuclides through the EBS to the near-field host rock. Lateral diversion of liquid water within the drift will occur at the inner drift surface, and more significantly from the operation of engineered structures such as drip shields and the outer surface of waste packages. If most of the seepage flux can be diverted laterally and removed from the drifts before contacting the wastes, the release of radionuclides from the EBS can be controlled, resulting in a proportional reduction in dose release at the accessible environment. The purposes

  17. Density Distributions of Cyclotrimethylenetrinitramines (RDX)

    SciTech Connect

    Hoffman, D M

    2002-03-19

    As part of the US Army Foreign Comparative Testing (FCT) program the density distributions of six samples of class 1 RDX were measured using the density gradient technique. This technique was used in an attempt to distinguish between RDX crystallized by a French manufacturer (designated insensitive or IRDX) from RDX manufactured at Holston Army Ammunition Plant (HAAP), the current source of RDX for Department of Defense (DoD). Two samples from different lots of French IRDX had an average density of 1.7958 {+-} 0.0008 g/cc. The theoretical density of a perfect RDX crystal is 1.806 g/cc. This yields 99.43% of the theoretical maximum density (TMD). For two HAAP RDX lots the average density was 1.786 {+-} 0.002 g/cc, only 98.89% TMD. Several other techniques were used for preliminary characterization of one lot of French IRDX and two lot of HAAP RDX. Light scattering, SEM and polarized optical microscopy (POM) showed that SNPE and Holston RDX had the appropriate particle size distribution for Class 1 RDX. High performance liquid chromatography showed quantities of HMX in HAAP RDX. French IRDX also showed a 1.1 C higher melting point compared to HAAP RDX in the differential scanning calorimetry (DSC) consistent with no melting point depression due to the HMX contaminant. A second part of the program involved characterization of Holston RDX recrystallized using the French process. After reprocessing the average density of the Holston RDX was increased to 1.7907 g/cc. Apparently HMX in RDX can act as a nucleating agent in the French RDX recrystallization process. The French IRDX contained no HMX, which is assumed to account for its higher density and narrower density distribution. Reprocessing of RDX from Holston improved the average density compared to the original Holston RDX, but the resulting HIRDX was not as dense as the original French IRDX. Recrystallized Holston IRDX crystals were much larger (3-500 {micro}m or more) then either the original class 1 HAAP RDX or

  18. Distributed Aviation Concepts and Technologies

    NASA Technical Reports Server (NTRS)

    Moore, Mark D.

    2008-01-01

    Aviation has experienced one hundred years of evolution, resulting in the current air transportation system dominated by commercial airliners in a hub and spoke infrastructure. While the first fifty years involved disruptive technologies that required frequent vehicle adaptation, the second fifty years produced a stable evolutionary optimization of decreasing costs with increasing safety. This optimization has resulted in traits favoring a centralized service model with high vehicle productivity and cost efficiency. However, it may also have resulted in a system that is not sufficiently robust to withstand significant system disturbances. Aviation is currently facing rapid change from issues such as environmental damage, terrorism threat, congestion and capacity limitations, and cost of energy. Currently, these issues are leading to a loss of service for weaker spoke markets. These catalysts and a lack of robustness could result in a loss of service for much larger portions of the aviation market. The impact of other competing transportation services may be equally important as casual factors of change. Highway system forecasts indicate a dramatic slow down as congestion reaches a point of non-linearly increasing delay. In the next twenty-five years, there is the potential for aviation to transform itself into a more robust, scalable, adaptive, secure, safe, affordable, convenient, efficient and environmentally friendly system. To achieve these characteristics, the new system will likely be based on a distributed model that enables more direct services. Short range travel is already demonstrating itself to be inefficient with a centralized model, providing opportunities for emergent distributed services through air-taxi models. Technologies from the on-demand revolution in computers and communications are now available as major drivers for aviation on-demand adaptation. Other technologies such as electric propulsion are currently transforming the automobile

  19. Can Data Recognize Its Parent Distribution?

    SciTech Connect

    A.W.Marshall; J.C.Meza; and I. Olkin

    1999-05-01

    This study is concerned with model selection of lifetime and survival distributions arising in engineering reliability or in the medical sciences. We compare various distributions, including the gamma, Weibull and lognormal, with a new distribution called geometric extreme exponential. Except for the lognormal distribution, the other three distributions all have the exponential distribution as special cases. A Monte Carlo simulation was performed to determine sample sizes for which survival distributions can distinguish data generated by their own families. Two methods for decision are by maximum likelihood and by Kolmogorov distance. Neither method is uniformly best. The probability of correct selection with more than one alternative shows some surprising results when the choices are close to the exponential distribution.

  20. A guided tour of new tempered distributions

    NASA Astrophysics Data System (ADS)

    Schmeelk, John

    1990-10-01

    Laurent Schwartz, the principle architect of distribution theory, presented the impossibility of extending a form of multiplication to distribution theory. There have been many varieties of partial solutions to this problem. Some of the solutions contain heuristic computations done by physicists in quantum field theory. A recent strategy developed by J. Colombeau culminates with multiplication and integration theory for distributions. This paper develops this theory in the spirit of a sequence approach, much like fundamental sequences are to distributions. However, in the new tempered distribution theory the sequences can be noncountable. T. Todorov developed these techniques for new distributions. However, since so many applications require Fourier analysis, the new tempered distributions provide a natural setting for physics and signal analysis. The paper illustrates the product of two Dirac delta functionals, δ( x) δ( x). Other nonregular distributional products can also be computed in the same manner. The paper culminates with a new application of annihilation and creation operators in quantum field theory.

  1. Array distribution in data-parallel programs

    NASA Technical Reports Server (NTRS)

    Chatterjee, Siddhartha; Gilbert, John R.; Schreiber, Robert; Sheffler, Thomas J.

    1994-01-01

    We consider distribution at compile time of the array data in a distributed-memory implementation of a data-parallel program written in a language like Fortran 90. We allow dynamic redistribution of data and define a heuristic algorithmic framework that chooses distribution parameters to minimize an estimate of program completion time. We represent the program as an alignment-distribution graph. We propose a divide-and-conquer algorithm for distribution that initially assigns a common distribution to each node of the graph and successively refines this assignment, taking computation, realignment, and redistribution costs into account. We explain how to estimate the effect of distribution on computation cost and how to choose a candidate set of distributions. We present the results of an implementation of our algorithms on several test problems.

  2. Electricity distribution networks: Changing regulatory approaches

    NASA Astrophysics Data System (ADS)

    Cambini, Carlo

    2016-09-01

    Increasing the penetration of distributed generation and smart grid technologies requires substantial investments. A study proposes an innovative approach that combines four regulatory tools to provide economic incentives for distribution system operators to facilitate these innovative practices.

  3. Distributed PV Adoption in Maine Through 2021

    SciTech Connect

    Gagnon, Pieter; Sigrin, Ben

    2015-11-06

    NREL has used its dSolar (distributed solar) model to generate low-medium-high estimates of distributed PV adoption in Maine through 2021. This presentation gives a high-level overview of the model and modeling results.

  4. Patterns of Drug Distribution: Implications and Issues#

    PubMed Central

    Johnson, Bruce D.

    2007-01-01

    This article delineates various patterns of illicit sales of drugs, especially at the retail (and near-retail) level, addressing a variety of central issues about drug sales and distribution documented during the past 30 years, including: a) the links between drug consumption and drug distribution activities; b) the various distribution roles; c) various levels of the distribution hierarchy; d) types of retail and wholesale markets; e) the association of drug distribution with nondrug associated criminality and violence. The article also will address the implications of drug distribution: whether various public policies such as supply reduction and source interdiction affect illicit drug markets, and how policing strategies and various law enforcement strategies can influence the involvement of individual participation in drug distribution activities. The overlooked contribution of treatment for “drug abuse” to reducing drug sales and distribution activities also will be considered as will other critical unresolved issues. PMID:14582578

  5. The Molecular Weight Distribution of Polymer Samples

    ERIC Educational Resources Information Center

    Horta, Arturo; Pastoriza, M. Alejandra

    2007-01-01

    Various methods for the determination of the molecular weight distribution (MWD) of different polymer samples are presented. The study shows that the molecular weight averages and distribution of a polymerization completely depend on the characteristics of the reaction itself.

  6. Distributive Justice and the Moral Development Curriculum.

    ERIC Educational Resources Information Center

    Krogh, Suzanne Lowell; Lamme, Linda Leonard

    1985-01-01

    Teaching strategies to help elementary social studies teachers teach distributive justice--i.e., fair sharing of available resources--are provided. Also described are the approximate age levels and the different levels of reasoning associated with distributive justice. (RM)

  7. Radon Transform and Light-Cone Distributions

    NASA Astrophysics Data System (ADS)

    Teryaev, O. V.

    2016-08-01

    The relevance of Radon transform for generalized and transverse momentum dependent parton distributions is discussed. The new application for conditional (fracture) parton distributions and dihadron fragmentation functions is suggested.

  8. Telemedicine and distributed medical intelligence.

    PubMed

    Warner, D; Tichenor, J M; Balch, D C

    1996-01-01

    Recent trends in health care informatics and telemedicine indicate that systems are being developed with a primary focus on technology and business, not on the process of medicine itself. The authors present a new model of health care information, distributed medical intelligence, which promotes the development of an integrative medical communication system addressing the process of providing expert medical knowledge to the point of need. The model incorporates audio, video, high-resolution still images, and virtual reality applications into an integrated medical communications network. Three components of the model (care portals, Docking Station, and the bridge) are described. The implementation of this model at the East Carolina University School of Medicine is also outlined. PMID:10165366

  9. Distributed Data Flow Signal Processors

    NASA Astrophysics Data System (ADS)

    Eggert, Jay A.

    1982-12-01

    Near term advances in technology such as VHSIC promise revolutionary progress in programmable signal processor capabilities. However, meeting projected signal processing requirements for radar, sonar and other high throughput systems requires effective multi-processor networks. This paper describes a distributed signal processor architecture currently in development at Texas Instruments that is designed to meet these high through-put, multi-mode system requirements. The approach supports multiple, functionally spe-cialized, autonomous nodes (processors) interconnected via a flexible, high speed communication network. A common task scheduling mechanism based upon "data flow" concepts provides an efficient high level programming and simulation mechanism. The Ada syntax compatible task level programming and simulation software support tools are also described.

  10. Concepts for Distributed Engine Control

    NASA Technical Reports Server (NTRS)

    Culley, Dennis E.; Thomas, Randy; Saus, Joseph

    2007-01-01

    Gas turbine engines for aero-propulsion systems are found to be highly optimized machines after over 70 years of development. Still, additional performance improvements are sought while reduction in the overall cost is increasingly a driving factor. Control systems play a vitally important part in these metrics but are severely constrained by the operating environment and the consequences of system failure. The considerable challenges facing future engine control system design have been investigated. A preliminary analysis has been conducted of the potential benefits of distributed control architecture when applied to aero-engines. In particular, reductions in size, weight, and cost of the control system are possible. NASA is conducting research to further explore these benefits, with emphasis on the particular benefits enabled by high temperature electronics and an open-systems approach to standardized communications interfaces.

  11. Embodied and Distributed Parallel DJing.

    PubMed

    Cappelen, Birgitta; Andersson, Anders-Petter

    2016-01-01

    Everyone has a right to take part in cultural events and activities, such as music performances and music making. Enforcing that right, within Universal Design, is often limited to a focus on physical access to public areas, hearing aids etc., or groups of persons with special needs performing in traditional ways. The latter might be people with disabilities, being musicians playing traditional instruments, or actors playing theatre. In this paper we focus on the innovative potential of including people with special needs, when creating new cultural activities. In our project RHYME our goal was to create health promoting activities for children with severe disabilities, by developing new musical and multimedia technologies. Because of the users' extreme demands and rich contribution, we ended up creating both a new genre of musical instruments and a new art form. We call this new art form Embodied and Distributed Parallel DJing, and the new genre of instruments for Empowering Multi-Sensorial Things.

  12. Cooperative Fault Tolerant Distributed Computing

    SciTech Connect

    Fagg, Graham E.

    2006-03-15

    HARNESS was proposed as a system that combined the best of emerging technologies found in current distributed computing research and commercial products into a very flexible, dynamically adaptable framework that could be used by applications to allow them to evolve and better handle their execution environment. The HARNESS system was designed using the considerable experience from previous projects such as PVM, MPI, IceT and Cumulvs. As such, the system was designed to avoid any of the common problems found with using these current systems, such as no single point of failure, ability to survive machine, node and software failures. Additional features included improved inter-component connectivity, with full support for dynamic down loading of addition components at run-time thus reducing the stress on application developers to build in all the libraries they need in advance.

  13. Embodied and Distributed Parallel DJing.

    PubMed

    Cappelen, Birgitta; Andersson, Anders-Petter

    2016-01-01

    Everyone has a right to take part in cultural events and activities, such as music performances and music making. Enforcing that right, within Universal Design, is often limited to a focus on physical access to public areas, hearing aids etc., or groups of persons with special needs performing in traditional ways. The latter might be people with disabilities, being musicians playing traditional instruments, or actors playing theatre. In this paper we focus on the innovative potential of including people with special needs, when creating new cultural activities. In our project RHYME our goal was to create health promoting activities for children with severe disabilities, by developing new musical and multimedia technologies. Because of the users' extreme demands and rich contribution, we ended up creating both a new genre of musical instruments and a new art form. We call this new art form Embodied and Distributed Parallel DJing, and the new genre of instruments for Empowering Multi-Sensorial Things. PMID:27534347

  14. Hourly temporal distribution of wind

    NASA Astrophysics Data System (ADS)

    Deligiannis, Ilias; Dimitriadis, Panayiotis; Koutsoyiannis, Demetris

    2016-04-01

    The wind process is essential for hydrometeorology and additionally, is one of the basic renewable energy resources. Most stochastic forecast models are limited up to daily scales disregarding the hourly scale which is significant for renewable energy management. Here, we analyze hourly wind timeseries giving emphasis on the temporal distribution of wind within the day. We finally present a periodic model based on statistical as well as hydrometeorological reasoning that shows good agreement with data. Acknowledgement: This research is conducted within the frame of the undergraduate course "Stochastic Methods in Water Resources" of the National Technical University of Athens (NTUA). The School of Civil Engineering of NTUA provided moral support for the participation of the students in the Assembly.

  15. Load distribution in native cellulose.

    PubMed

    Hinterstoisser, Barbara; Akerholm, Margaretha; Salmén, Lennart

    2003-01-01

    The properties of cellulose materials are dependent on interactions between and within the cellulose chains. To investigate the deformation behavior of cellulose and its relation to molecular straining, sheets with fibers oriented preferably in one direction were studied by dynamic FT-IR spectroscopy. Celluloses with different origins (spruce pulp, Cladophora cellulose, cotton linters) were used. The sheets were stretched sinusoidally at low strains and small amplitudes while being irradiated with polarized infrared radiation. The cellulose fibers showed mainly an elastic response. The cellulose fibers showed mainly an elastic response. The glucose rings and the C-O-C bridges connecting adjacent rings, as well as the O(3)H.O(5) intramolecular hydrogen bonds are the components mainly deformed under stress, whereas the O(2)H.O(6) intramolecular hydrogen bonds play a minor role. The load distribution was also found to be different in the different allomorphic forms of cellulose I, namely, I(alpha) and I(beta).

  16. The Outer Halo Metallicity Distribution

    NASA Astrophysics Data System (ADS)

    MA, ZHIBO; Morrison, H.; Harding, P.; Xue, X.; Rix, H.; Rockosi, C.; Johnson, J.; Lee, Y.; Cudworth, K.

    2012-01-01

    We present a new determination of the metallicity distribution function in the Milky Way halo, based on an in situ sample of more than 5000 K giants from SDSS/SEGUE. We have also measured the metallicity gradient in the halo, using our sample which stretches from 5 kpc to more than 100 kpc from the galactic center. The halo metallicity gradient has been a controversial topic in recent studies, but our in-situ study overcomes the problems caused in these studies by their extrapolations from local samples to the distant halo. We also describe our extensive checks of the log g and [Fe/H] measurements from the SEGUE Stellar Parameters pipeline, using globular and open cluster stars and SEGUE stars with follow-up high-resolution analysis. In addition, we present a new Bayesian estimate of distances to the K giants, which avoids the distance bias introduced by the red giant branch luminosity function.

  17. Distribution of multidirectional environmental effects

    SciTech Connect

    Bitner-Gregersen, E.M.

    1996-12-31

    An extension of the joint environmental model developed for Haltenbanken (off central Norway) is presented. The existing model is limited to the following environmental parameters: 1-hour mean wind speed, current speed, significant wave height (sea and swell), spectral peak period (sea and swell), the main wave direction (wind and current are assumed to be collinear with the main wave direction) and sea water level. The model has been based on experience gained from measurements and hindcast data from the Norwegian Continental Shelf. The extension of the joint environmental model includes the possibility of environmental effects approaching from different directions. It is based on hindcast data and developed for severe weather conditions. A procedure for inclusion a lower limit in the wave period distribution, as an alternative to application of a double peak spectrum, is also proposed. The model is meant to provide an input to reliability analysis of offshore structures.

  18. Deuteron distribution in nuclear matter

    NASA Astrophysics Data System (ADS)

    Benhar, O.; Fabrocini, A.; Fantoni, S.; Illarionov, A. Yu.; Lykasov, G. I.

    2002-05-01

    We analyze the properties of deuteron-like structures in infinite, correlated nuclear matter, described by a realistic hamiltonian containing the Urbana v14 two-nucleon and the Urbana TNI many-body potentials. The distribution of neutron-proton pairs, carrying the deuteron quantum numbers, is obtained as a function of the total momentum by computing the overlap between the nuclear matter in its ground state and the deuteron wave functions in correlated basis functions theory. We study the differences between the S- and D-wave components of the deuteron and those of the deuteron-like pair in the nuclear medium. The total number of deuteron type pairs is computed and compared with the predictions of Levinger's quasideuteron model. The resulting Levinger's factor in nuclear matter at equilibrium density is 11.63. We use the local density approximation to estimate the Levinger's factor for heavy nuclei, obtaining results which are consistent with the available experimental data from photoreactions.

  19. Parton distributions with threshold resummation

    NASA Astrophysics Data System (ADS)

    Bonvini, Marco; Marzani, Simone; Rojo, Juan; Rottoli, Luca; Ubiali, Maria; Ball, Richard D.; Bertone, Valerio; Carrazza, Stefano; Hartland, Nathan P.

    2015-09-01

    We construct a set of parton distribution functions (PDFs) in which fixed-order NLO and NNLO calculations are supplemented with soft-gluon (threshold) resummation up to NLL and NNLL accuracy respectively, suitable for use in conjunction with any QCD calculation in which threshold resummation is included at the level of partonic cross sections. These resummed PDF sets, based on the NNPDF3.0 analysis, are extracted from deep-inelastic scattering, Drell-Yan, and top quark pair production data, for which resummed calculations can be consistently used. We find that, close to threshold, the inclusion of resummed PDFs can partially compensate the enhancement in resummed matrix elements, leading to resummed hadronic cross-sections closer to the fixed-order calculations. On the other hand, far from threshold, resummed PDFs reduce to their fixed-order counterparts. Our results demonstrate the need for a consistent use of resummed PDFs in resummed calculations.

  20. Interoperability of heterogeneous distributed systems

    NASA Astrophysics Data System (ADS)

    Zaschke, C.; Essendorfer, B.; Kerth, C.

    2016-05-01

    To achieve knowledge superiority in today's operations interoperability is the key. Budget restrictions as well as the complexity and multiplicity of threats combined with the fact that not single nations but whole areas are subject to attacks force nations to collaborate and share information as appropriate. Multiple data and information sources produce different kinds of data, real time and non-real time, in different formats that are disseminated to the respective command and control level for further distribution. The data is most of the time highly sensitive and restricted in terms of sharing. The question is how to make this data available to the right people at the right time with the right granularity. The Coalition Shared Data concept aims to provide a solution to these questions. It has been developed within several multinational projects and evolved over time. A continuous improvement process was established and resulted in the adaptation of the architecture as well as the technical solution and the processes it supports. Coming from the idea of making use of existing standards and basing the concept on sharing of data through standardized interfaces and formats and enabling metadata based query the concept merged with a more sophisticated service based approach. The paper addresses concepts for information sharing to facilitate interoperability between heterogeneous distributed systems. It introduces the methods that were used and the challenges that had to be overcome. Furthermore, the paper gives a perspective how the concept could be used in the future and what measures have to be taken to successfully bring it into operations.

  1. Ecophysiological controls of conifer distributions

    SciTech Connect

    Woodward, F.I.

    1995-07-01

    The boreal forest covers the most extensive worldwide area of conifer-dominated vegetation, with a total global area of about 12 million km{sup 2}. This large area is very species poor; in North America there are only nine widespread and dominant species of trees, of which six are conifers-Picea mariana, Picea glauca, Abies balsamea, Larix laricina, Pinus contorta, and Pinus banksiana. The remaining three angiosperms are Betula papyrifera, Populus tremuloides, and Populus balsamifera. In Fennoscandia and the former Soviet Union, 14 species dominate the boreal forest, 10 of which are conifers-Abies sibirica, Larix gmelinii, Larix sibirica, Larix sukaczewii, Picea abies, Picea ajanensis, Picea obovata, Pinus pumila, Pinus sibifica, and Pinus sylvestris. The dominant angiosperm trees are Betula pendula, Betula pubescens, Chosenia arbutifolia, and Populus tremula. Such species paucity detracts from realizing the remarkable capacity of these species to endure the harshest forest climates of the world. Both the short-term geological history and the current climate are major causes of the species paucity in the boreal forest. In general, the boreal forest has been present in its current distribution only since the Holocene era. In most cases, the dominant species of the boreal forest completed their postglacial expansion to their current distributions only over the past 2000 years. So the ecology of the forest is very young, in comparison with forests in warmer climates. It might be expected that over subsequent millennia, with no climatic change, there could be a slow influx of new species to the boreal zone; however, the extreme climatic, edaphic, and disturbance characteristics of the area are likely to set insurmountable limits on this influx of diversity.

  2. Velocity distributions for fast rotating nuclei

    SciTech Connect

    Wu, X.; Zhang, X.; Zhuo, Y.; Feng, R.

    1982-01-01

    The velocity field is calculated on the basis of the exact wave functions of the cranked deformed harmonic oscillator by including the term of ..delta..N = 2 subject to the conditions of isotropic velocity distribution and self-consistency between potential and density distribution. We study the characteristics of velocity distributions of nuclei with the large rotational frequencies. We also discuss the effects of two types of self-consistency conditions on the velocity distributions.

  3. Velocity distributions of photochemically desorbed molecules

    NASA Astrophysics Data System (ADS)

    Zimmermann, Frank M.; Ho, W.

    1994-05-01

    The standard picture of desorption induced by electronic transitions (DIET) is analyzed for high excited state quenching rates. Simple dynamical considerations are found to explain the velocity distributions characterizing a large number of photodesorption and electron stimulated desorption systems. Without invoking any thermalization processes, the model predicts a Maxwell-Boltzmann velocity distribution, thus providing a theoretical justification for this distribution's widespread use as an empirical fitting formula for velocity distributions of nonthermally desorbed species.

  4. 25 CFR 273.31 - Distribution formula.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false Distribution formula. 273.31 Section 273.31 Indians... ACT PROGRAM EDUCATION CONTRACTS UNDER JOHNSON-O'MALLEY ACT Funding Provisions § 273.31 Distribution... the purpose shall be allotted pro rata in accordance with the distribution method outlined in...

  5. Adult Distributive Education: A Neglected Component?

    ERIC Educational Resources Information Center

    Wray, Ralph D.

    1976-01-01

    Distributive education personnel must find solutions to some unique problems (lack of leadership, fiscal policies, local motivation, and research) if adult distributive education offerings are to become a more vital and flourishing component of the total distributive education program. (Author/BP)

  6. ADDE: Application Development for the Distributed Enterprise.

    ERIC Educational Resources Information Center

    Franckson, Marcel; Hall, John; Helmerich, Alfred; Canadas, Rafael; Dehn, Martin

    1998-01-01

    Describes the Application Development for the Distributed Enterprise (ADDE) project, a methodological set that supports the design of distributed business processes and information and communication technologies. Discusses principles behind ADDE, guidance on definition and planning of application development, guidance on distributed application…

  7. Investigating School Leadership Practice: A Distributed Perspective.

    ERIC Educational Resources Information Center

    Spillane, James P.; Halverson, Richard; Diamond, John B.

    2001-01-01

    Argues for scholarship that investigates leadership practice; specifically, the practice of leading classroom instruction. Articulates a distributed perspective, grounded in activity theory and distributed cognition, to frame such investigations. Suggests that school leadership is best understood as a distributed practice stretched over the…

  8. The Tsallis distribution at the LHC: Phenomenology

    SciTech Connect

    Cleymans, J.

    2014-11-11

    An overview is presented of transverse momentum distributions of particles at the LHC using the Tsallis distribution. The use of a thermodynamically consistent form of this distribution leads to an excellent description of charged and identified particles. The values of the Tsallis parameter q are truly remarkably consistent.

  9. 7 CFR 1000.5 - Distributing plant.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 9 2012-01-01 2012-01-01 false Distributing plant. 1000.5 Section 1000.5 Agriculture... Definitions § 1000.5 Distributing plant. Distributing plant means a plant that is approved by a duly... plants....

  10. 7 CFR 1000.5 - Distributing plant.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 9 2013-01-01 2013-01-01 false Distributing plant. 1000.5 Section 1000.5 Agriculture... Definitions § 1000.5 Distributing plant. Distributing plant means a plant that is approved by a duly... plants....

  11. 7 CFR 1000.5 - Distributing plant.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 9 2014-01-01 2013-01-01 true Distributing plant. 1000.5 Section 1000.5 Agriculture... Definitions § 1000.5 Distributing plant. Distributing plant means a plant that is approved by a duly... plants....

  12. Distributed Pervasive Worlds: The Case of Exergames

    ERIC Educational Resources Information Center

    Laine, Teemu H.; Sedano, Carolina Islas

    2015-01-01

    Pervasive worlds are computing environments where a virtual world converges with the physical world through context-aware technologies such as sensors. In pervasive worlds, technology is distributed among entities that may be distributed geographically. We explore the concept, possibilities, and challenges of distributed pervasive worlds in a case…

  13. Distributed Leadership through the Looking Glass

    ERIC Educational Resources Information Center

    Harris, Alma; Spillane, James

    2008-01-01

    Distributed leadership is an idea that is growing in popularity. There is widespread interest in the notion of distributing leadership although interpretations of the term vary. A distributed leadership perspective recognises that there are multiple leaders and that leadership activities are widely shared within and between organisations. A…

  14. Modelling Documents with Multiple Poisson Distributions.

    ERIC Educational Resources Information Center

    Margulis, Eugene L.

    1993-01-01

    Reports on the validity of the Multiple Poisson (nP) model of word distribution in full-text document collections. A practical algorithm for determining whether a certain word is distributed according to an nP distribution and the results of a test of this algorithm in three different document collections are described. (14 references) (KRN)

  15. 14 CFR 29.1355 - Distribution system.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Equipment Electrical Systems and Equipment § 29.1355 Distribution system. (a) The distribution system includes the distribution busses, their associated feeders, and each control and protective device. (b) If two independent sources of electrical power...

  16. 14 CFR 25.1355 - Distribution system.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Equipment Electrical Systems and Equipment § 25.1355 Distribution system. (a) The distribution system includes the distribution busses, their associated feeders, and each control and protective device. (b) (c) If two independent sources of electrical power...

  17. 7 CFR 1000.5 - Distributing plant.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 9 2010-01-01 2009-01-01 true Distributing plant. 1000.5 Section 1000.5 Agriculture... Definitions § 1000.5 Distributing plant. Distributing plant means a plant that is approved by a duly... plants....

  18. 7 CFR 1000.5 - Distributing plant.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 9 2011-01-01 2011-01-01 false Distributing plant. 1000.5 Section 1000.5 Agriculture... Definitions § 1000.5 Distributing plant. Distributing plant means a plant that is approved by a duly... plants....

  19. Household income distribution in the USA

    NASA Astrophysics Data System (ADS)

    Efthimiou, Costas J.; Wearne, Adam

    2016-03-01

    In this article we present an alternative model for the distribution of household incomes in the United States. We provide arguments from two differing perspectives which both yield the proposed income distribution curve, and then fit this curve to empirical data on household income distribution obtained from the United States Census Bureau.

  20. Models of sporadic meteor body distributions

    NASA Technical Reports Server (NTRS)

    Andreev, V. V.; Belkovich, O. I.

    1987-01-01

    The distribution of orbital elements and flux density over the celestial sphere are the most common forms of representation of the meteor body distribution in the vicinity of the Earth's orbit. The determination of flux density distribution of sporadic meteor bodies was worked out. The method and its results are discussed.

  1. Multimedia Environmental Distribution of Nanomaterials

    NASA Astrophysics Data System (ADS)

    Liu, Haoyang Haven

    Engineered nanomaterials (ENMs), which may be released to the environment due to human-related activities, can move across environmental phase boundaries and be found in most media. Given the rapid development and growing applications of nanotechnology, there is concern and thus the need to assess the potential environmental impact associated with ENMs. Accordingly, a modeling platform was developed to enable evaluation of the dynamic multimedia environmental distribution of ENMs (MendNano) and the range of potential exposure concentrations of ENMs. The MendNano was based on a dynamic multimedia compartmental modeling approach that was guided by detailed analysis of the agglomeration of ENMs, life-cycle analysis based estimates of their potential release to the environment, and incorporation of mechanistic sub-models of various intermedia transport processes. Model simulations for various environmental scenarios indicated that ENM accumulation in the sediment increased significantly with increased ENMs attachment to suspended solids in water. Atmospheric dry and wet depositions can be important pathways for ENMs input to the terrestrial environment in the absence of direct and distributed ENM release to soil. Increased ENM concentration in water due to atmospheric deposition (wet and dry) is expected as direct ENM release to water diminishes. However, for soluble ENMs dissolution can be the dominant pathway for suspended ENM removal from water even compared to advective transport. For example, simulations for Los Angeles showed that dry deposition, rain scavenging, and wind dilution can remove 90% of ENMs from the atmospheric airshed in ~100-230 days, ~2-6 hrs, and ~0.5-2 days, respectively. For the evaluated ENMs (metal, metal oxides, carbon nanotubes (CNT), nanoclays), mass accumulation in the multimedia environment was mostly in the soil and sediment. Additionally, simulation results for TiO2 in Los Angeles demonstrates that the ENM concentrations in air and

  2. Electric field distribution of electron emitter surfaces

    NASA Astrophysics Data System (ADS)

    Tagawa, M.; Takenobu, S.; Ohmae, N.; Umeno, M.

    1987-03-01

    The electric field distribution of a tungsten field emitter surface and a LaB6 thermionic emitter surface has been studied. The computer simulation of electric field distribution on the emitter surface was carried out with a charge simulation method. The electric field distribution of the LaB6 thermionic emitter was experimentally evaluated by the Schottky plot. Two independent equations are necessary for obtaining local electric field and work function; the Fowler-Nordheim equation and the equation of total energy distribution of emitted electron being used to evaluate the electric field distribution of the tungsten field emitter. The experimental results agreed with the computer simulation.

  3. Positive phase space distributions and uncertainty relations

    NASA Technical Reports Server (NTRS)

    Kruger, Jan

    1993-01-01

    In contrast to a widespread belief, Wigner's theorem allows the construction of true joint probabilities in phase space for distributions describing the object system as well as for distributions depending on the measurement apparatus. The fundamental role of Heisenberg's uncertainty relations in Schroedinger form (including correlations) is pointed out for these two possible interpretations of joint probability distributions. Hence, in order that a multivariate normal probability distribution in phase space may correspond to a Wigner distribution of a pure or a mixed state, it is necessary and sufficient that Heisenberg's uncertainty relation in Schroedinger form should be satisfied.

  4. Efficient Session Type Guided Distributed Interaction

    NASA Astrophysics Data System (ADS)

    Sivaramakrishnan, K. C.; Nagaraj, Karthik; Ziarek, Lukasz; Eugster, Patrick

    Recently, there has been much interest in multi-party session types (MPSTs) as a means of rigorously specifying protocols for interaction among multiple distributed participants. By capturing distributed interaction as series of typed interactions, MPSTs allow for the static verification of compliance of corresponding distributed object programs. We observe that explicit control flow information manifested by MPST opens intriguing avenues also for performance enhancements. In this paper, we present a session type assisted performance enhancement framework for distributed object interaction in Java. Experimental evaluation within our distributed runtime infrastructure illustrates the costs and benefits of our composable enhancement strategies.

  5. Experiences with distributing graphic software between processors

    SciTech Connect

    Hamlin, G.; George, J.E.

    1982-01-01

    Software to aid the distribution and coordination of tasks between different processors was developed to distribute applications written in Fortran. This development led to the discovery of problems unique to Fortran and to interesting practical solutions. Two graphical applications were distributed to a variety of machines and machine pairs: CDC 7600-LSI/11, CRAY-LSI/11, VAX 11/780, and Apollo. These distributions pointed out several parameters such as the use of Fortran COMMON, communication parameters, and processing capabilities that can affect the successful distribution of applications.

  6. Diffraction Theory and Almost Periodic Distributions

    NASA Astrophysics Data System (ADS)

    Strungaru, Nicolae; Terauds, Venta

    2016-09-01

    We introduce and study the notions of translation bounded tempered distributions, and autocorrelation for a tempered distribution. We further introduce the spaces of weakly, strongly and null weakly almost periodic tempered distributions and show that for weakly almost periodic tempered distributions the Eberlein decomposition holds. For translation bounded measures all these notions coincide with the classical ones. We show that tempered distributions with measure Fourier transform are weakly almost periodic and that for this class, the Eberlein decomposition is exactly the Fourier dual of the Lebesgue decomposition, with the Fourier-Bohr coefficients specifying the pure point part of the Fourier transform. We complete the project by looking at few interesting examples.

  7. Distribution characteristics of stock market liquidity

    NASA Astrophysics Data System (ADS)

    Luo, Jiawen; Chen, Langnan; Liu, Hao

    2013-12-01

    We examine the distribution characteristics of stock market liquidity by employing the generalized additive models for location, scale and shape (GAMLSS) model and three-minute frequency data from Chinese stock markets. We find that the BCPE distribution within the GAMLSS framework fits the distributions of stock market liquidity well with the diagnosis test. We also find that the stock market index exhibits a significant impact on the distributions of stock market liquidity. The stock market liquidity usually exhibits a positive skewness, but a normal distribution at a low level of stock market index and a high-peak and fat-tail shape at a high level of stock market index.

  8. Transverse Momentum Dependent Distributions in Hard Scattering

    SciTech Connect

    Alexie Prokudin

    2011-05-01

    Transverse Momentum Dependent Distributions (TMDs) describe the spin structure of the proton. At leading twist spin structure of spin-1/2 hadron can be described by 8 TMDs. TMDs reveal three-dimensional distribution of partons inside polarised nucleon. Experimentally these functions can be studied in polarised experiments using Spin Asymmetries in particular Single Spin Asymmetries (SSAs). We discuss transversity that measures distribution of transversely polarised quarks in a transversely polarised nucleon and Sivers distribution function that describes distribution of unpolarised quarks in a transversely polarised nucleon.

  9. Experiences with distributing graphic software between processors

    SciTech Connect

    Hamlin, G.; George, J.E.

    1982-01-01

    Software to aid the distribution and coordination of tasks between different processors was developed to distribute applications written in Fortran. This development led to the discovery of problems unique to Fortran and to interesting practical solutions. Two graphical applications were distributed to a variety of machines and machine pairs: CDC 7600-LSI/11, Cray-LSI/11, VAX 11/780, and Apollo. These distributions pointed out several parameters such as the use of Fortran Common, communication parameters, and processing capabilities that can affect the successful distribution of applications.

  10. Influence of breakup on fusion barrier distributions

    NASA Astrophysics Data System (ADS)

    Patel, D.; Nayak, B. K.; Mukherjee, S.; Biswas, D. C.; Mirgule, E. T.; John, B. V.; Gupta, Y. K.; Mukhopadhyay, S.; Prajapati, G.; Danu, L. S.; Rath, P. K.; Desai, V.; Deshmukh, N.; Saxena, A.

    2013-04-01

    Fusion barrier distributions have been extracted from the quasi-elastic scattering excitation functions, measured at backward angle θlab = 160° in reactions of 6,7Li+209Bi. The present results have been compared with the barrier distributions obtained from the fusion excitation function measurements for the above mentioned systems. The fusion barrier distributions from the quasi-elastic scattering excitation functions have been analyzed with simplified Coupled Channels calculations using Fresco. Inclusions of resonant states for both 6,7Li projectiles improve the predictions to describe the measured quasi-elastic scattering excitation functions and barrier distributions. For both the reactions peak positions of fusion barrier distributions are shifted towards a lower energy side in comparison to that obtained from the fusion excitation function measurements. The observed discrepancy in peak positions of barrier distributions obtained from quasi-elastic scattering and fusion excitation function measurements has been discussed in terms of total reaction threshold distribution.

  11. Bernstein instability driven by thermal ring distribution

    SciTech Connect

    Yoon, Peter H.; Hadi, Fazal; Qamar, Anisa

    2014-07-15

    The classic Bernstein waves may be intimately related to banded emissions detected in laboratory plasmas, terrestrial, and other planetary magnetospheres. However, the customary discussion of the Bernstein wave is based upon isotropic thermal velocity distribution function. In order to understand how such waves can be excited, one needs an emission mechanism, i.e., an instability. In non-relativistic collision-less plasmas, the only known Bernstein wave instability is that associated with a cold perpendicular velocity ring distribution function. However, cold ring distribution is highly idealized. The present Brief Communication generalizes the cold ring distribution model to include thermal spread, so that the Bernstein-ring instability is described by a more realistic electron distribution function, with which the stabilization by thermal spread associated with the ring distribution is demonstrated. The present findings imply that the excitation of Bernstein waves requires a sufficiently high perpendicular velocity gradient associated with the electron distribution function.

  12. Low jitter RF distribution system

    DOEpatents

    Wilcox, Russell; Doolittle, Lawrence; Huang, Gang

    2012-09-18

    A timing signal distribution system includes an optical frequency stabilized laser signal amplitude modulated at an rf frequency. A transmitter box transmits a first portion of the laser signal and receive a modified optical signal, and outputs a second portion of the laser signal and a portion of the modified optical signal. A first optical fiber carries the first laser signal portion and the modified optical signal, and a second optical fiber carries the second portion of the laser signal and the returned modified optical signal. A receiver box receives the first laser signal portion, shifts the frequency of the first laser signal portion outputs the modified optical signal, and outputs an electrical signal on the basis of the laser signal. A detector at the end of the second optical fiber outputs a signal based on the modified optical signal. An optical delay sensing circuit outputs a data signal based on the detected modified optical signal. An rf phase detect and correct signal circuit outputs a signal corresponding to a phase stabilized rf signal based on the data signal and the frequency received from the receiver box.

  13. Distributed Processing of SETI Data

    NASA Astrophysics Data System (ADS)

    Korpela, Eric

    As you have read in prior chapters, researchers have been performing progressively more sensitive SETI searches since 1960. Each search has been limited by the technologies available at the time. As radio frequency technologies have become more efficient and computers have become faster, the searches have increased in capacity and become more sensitive. Often the limits of the hardware that performs the calculations required to process the telescope data in order to expose any embedded signals is what limits the sensitivity of the search. Shortly before the start of the 21st century, projects began to appear that exploited the processing capabilities of computers connected to the Internet in order to solve problems that required a large amount of computing power. The SETI@home project, managed by myself and a group of researchers at the Space Sciences Laboratory of the University of California, Berkeley, was the first attempt to use large-scale distributed computing to solve the problems of performing a sensitive search for narrow band radio signals from extraterrestrial civilizations. (Korpela et al., 2001) A follow-on project, Astropulse, searches for extraterrestrial signals with wider bandwidths and shorter time durations. Both projects are ongoing at the present time (mid-2010).

  14. The learnability of critical distributions

    NASA Astrophysics Data System (ADS)

    Schwab, David; Torrence, Johannah; Torlai, Giacomo; Melko, Roger; Palmer, Stephanie

    Many biological systems, including some neural population codes, have been shown empirically to sit near a critical point. Here we study the learnability of such codes. We first construct networks of interacting binary neurons with random, sparse interactions (i.e. a Erdos-Renyi graph) of uniform strength. We then characterize the discriminability of those interactions from data samples by performing a direct coupling analysis and thresholding the direct information between each pair of neurons to predict the presence or absence of an interaction. By sweeping through threshold values, we compute the area under the ROC curve as a measure of discriminability of the interactions. We show that the resulting discriminability is maximized when the original distribution is at its critical point. We next trained deep neural networks to discriminate between samples drawn from two nearby temperatures in the 2D Ising model. We find distinct signatures of decoding performance in the vicinity of the critical point. This technique may be useful for detecting phase transitions in models without an a priori identified order parameter.

  15. Organizing Diverse, Distributed Project Information

    NASA Technical Reports Server (NTRS)

    Keller, Richard M.

    2003-01-01

    SemanticOrganizer is a software application designed to organize and integrate information generated within a distributed organization or as part of a project that involves multiple, geographically dispersed collaborators. SemanticOrganizer incorporates the capabilities of database storage, document sharing, hypermedia navigation, and semantic-interlinking into a system that can be customized to satisfy the specific information-management needs of different user communities. The program provides a centralized repository of information that is both secure and accessible to project collaborators via the World Wide Web. SemanticOrganizer's repository can be used to collect diverse information (including forms, documents, notes, data, spreadsheets, images, and sounds) from computers at collaborators work sites. The program organizes the information using a unique network-structured conceptual framework, wherein each node represents a data record that contains not only the original information but also metadata (in effect, standardized data that characterize the information). Links among nodes express semantic relationships among the data records. The program features a Web interface through which users enter, interlink, and/or search for information in the repository. By use of this repository, the collaborators have immediate access to the most recent project information, as well as to archived information. A key advantage to SemanticOrganizer is its ability to interlink information together in a natural fashion using customized terminology and concepts that are familiar to a user community.

  16. DIDA: Distributed Indexing Dispatched Alignment

    PubMed Central

    Mohamadi, Hamid; Vandervalk, Benjamin P; Raymond, Anthony; Jackman, Shaun D; Chu, Justin; Breshears, Clay P; Birol, Inanc

    2015-01-01

    One essential application in bioinformatics that is affected by the high-throughput sequencing data deluge is the sequence alignment problem, where nucleotide or amino acid sequences are queried against targets to find regions of close similarity. When queries are too many and/or targets are too large, the alignment process becomes computationally challenging. This is usually addressed by preprocessing techniques, where the queries and/or targets are indexed for easy access while searching for matches. When the target is static, such as in an established reference genome, the cost of indexing is amortized by reusing the generated index. However, when the targets are non-static, such as contigs in the intermediate steps of a de novo assembly process, a new index must be computed for each run. To address such scalability problems, we present DIDA, a novel framework that distributes the indexing and alignment tasks into smaller subtasks over a cluster of compute nodes. It provides a workflow beyond the common practice of embarrassingly parallel implementations. DIDA is a cost-effective, scalable and modular framework for the sequence alignment problem in terms of memory usage and runtime. It can be employed in large-scale alignments to draft genomes and intermediate stages of de novo assembly runs. The DIDA source code, sample files and user manual are available through http://www.bcgsc.ca/platform/bioinfo/software/dida. The software is released under the British Columbia Cancer Agency License (BCCA), and is free for academic use. PMID:25923767

  17. Quantifying error distributions in crowding.

    PubMed

    Hanus, Deborah; Vul, Edward

    2013-03-22

    When multiple objects are in close proximity, observers have difficulty identifying them individually. Two classes of theories aim to account for this crowding phenomenon: spatial pooling and spatial substitution. Variations of these accounts predict different patterns of errors in crowded displays. Here we aim to characterize the kinds of errors that people make during crowding by comparing a number of error models across three experiments in which we manipulate flanker spacing, display eccentricity, and precueing duration. We find that both spatial intrusions and individual letter confusions play a considerable role in errors. Moreover, we find no evidence that a naïve pooling model that predicts errors based on a nonadditive combination of target and flankers explains errors better than an independent intrusion model (indeed, in our data, an independent intrusion model is slightly, but significantly, better). Finally, we find that manipulating trial difficulty in any way (spacing, eccentricity, or precueing) produces homogenous changes in error distributions. Together, these results provide quantitative baselines for predictive models of crowding errors, suggest that pooling and spatial substitution models are difficult to tease apart, and imply that manipulations of crowding all influence a common mechanism that impacts subject performance.

  18. Multimedia Environmental Distribution of Nanomaterials

    NASA Astrophysics Data System (ADS)

    Liu, Haoyang Haven

    Engineered nanomaterials (ENMs), which may be released to the environment due to human-related activities, can move across environmental phase boundaries and be found in most media. Given the rapid development and growing applications of nanotechnology, there is concern and thus the need to assess the potential environmental impact associated with ENMs. Accordingly, a modeling platform was developed to enable evaluation of the dynamic multimedia environmental distribution of ENMs (MendNano) and the range of potential exposure concentrations of ENMs. The MendNano was based on a dynamic multimedia compartmental modeling approach that was guided by detailed analysis of the agglomeration of ENMs, life-cycle analysis based estimates of their potential release to the environment, and incorporation of mechanistic sub-models of various intermedia transport processes. Model simulations for various environmental scenarios indicated that ENM accumulation in the sediment increased significantly with increased ENMs attachment to suspended solids in water. Atmospheric dry and wet depositions can be important pathways for ENMs input to the terrestrial environment in the absence of direct and distributed ENM release to soil. Increased ENM concentration in water due to atmospheric deposition (wet and dry) is expected as direct ENM release to water diminishes. However, for soluble ENMs dissolution can be the dominant pathway for suspended ENM removal from water even compared to advective transport. For example, simulations for Los Angeles showed that dry deposition, rain scavenging, and wind dilution can remove 90% of ENMs from the atmospheric airshed in ~100-230 days, ~2-6 hrs, and ~0.5-2 days, respectively. For the evaluated ENMs (metal, metal oxides, carbon nanotubes (CNT), nanoclays), mass accumulation in the multimedia environment was mostly in the soil and sediment. Additionally, simulation results for TiO2 in Los Angeles demonstrates that the ENM concentrations in air and

  19. Distributed Seams for Gigapixel Panoramas.

    PubMed

    Philip, Sujin; Summa, Brian; Tierny, Julien; Bremer, Peer-Timo; Pascucci, Valerio

    2015-03-01

    Gigapixel panoramas are an increasingly popular digital image application. They are often created as a mosaic of many smaller images. The mosaic acquisition can take many hours causing the individual images to differ in exposure and lighting conditions. A blending operation is often necessary to give the appearance of a seamless image. The blending quality depends on the magnitude of discontinuity along the image boundaries. Often, new boundaries, or seams, are first computed that minimize this transition. Current techniques based on multi-labeling Graph Cuts are too slow and memory intensive for gigapixel sized panoramas. In this paper, we present a parallel, out-of-core seam computing technique that is fast, has small memory footprint, and is capable of running efficiently on different types of parallel systems. Its maximum memory usage is configurable, in the form of a cache, which can improve performance by reducing redundant disk I/O and computations. It shows near-perfect scaling on symmetric multiprocessing systems and good scaling on clusters and distributed shared memory systems. Our technique improves the time required to compute seams for gigapixel imagery from many hours (or even days) to just a few minutes, while still producing boundaries with energy that is on-par with Graph Cuts. PMID:26357067

  20. Hierarchical model for distributed seismicity

    SciTech Connect

    Tejedor, Alejandro; Gomez, Javier B.; Pacheco, Amalio F.

    2010-07-15

    A cellular automata model for the interaction between seismic faults in an extended region is presented. Faults are represented by boxes formed by a different number of sites and located in the nodes of a fractal tree. Both the distribution of box sizes and the interaction between them is assumed to be hierarchical. Load particles are randomly added to the system, simulating the action of external tectonic forces. These particles fill the sites of the boxes progressively. When a box is full it topples, some of the particles are redistributed to other boxes and some of them are lost. A box relaxation simulates the occurrence of an earthquake in the region. The particle redistributions mostly occur upwards (to larger faults) and downwards (to smaller faults) in the hierarchy producing new relaxations. A simple and efficient bookkeeping of the information allows the running of systems with more than fifty million faults. This model is consistent with the definition of magnitude, i.e., earthquakes of magnitude m take place in boxes with a number of sites ten times bigger than those boxes responsible for earthquakes with a magnitude m-1 which are placed in the immediate lower level of the hierarchy. The three parameters of the model have a geometrical nature: the height or number of levels of the fractal tree, the coordination of the tree and the ratio of areas between boxes in two consecutive levels. Besides reproducing several seismicity properties and regularities, this model is used to test the performance of some precursory patterns.

  1. The compositional distribution of asteroids

    NASA Astrophysics Data System (ADS)

    DeMeo, F.; Carry, B.; Alexander, C.; Walsh, K.; Chapman, C.

    2014-07-01

    Each compositional class of asteroid is a relic of the temperature and composition conditions in which it formed. The current distribution reveals the history of the Solar System, and each body acts as a marker of any mixing that occurred since formation. The remnant of a primordial temperature gradient, seen as transition from the S class to C class dominating in different regions of the asteroid belt has been a paradigm for three decades [1-4]. Today, we are armed with major advancements from the past decade that have revolutionized the field of asteroids in areas such as discovery, physical characterization, and dynamical models. A new and more detailed compositional map [5,6] created with data from the Sloan Digital Sky Survey [7] allows us to re-examine compositional trends in the main asteroid belt and what the physical and dynamical implications might be. This talk is related to recent work from DeMeo & Carry 2013, 2014 [5,6] and an upcoming chapter of the "Asteroids IV" book in 2015.

  2. 13 CFR 107.1560 - Distributions by Licensee-required Distributions to private investors and SBA.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... (Leverage) Participating Securities Leverage § 107.1560 Distributions by Licensee—required Distributions to... as redemptions or repayments of Leverage; plus (3) All previous Distributions under § 107.1570(b... redemption of Leverage (see paragraph (g) of this section). (e) SBA's share of the total Distribution....

  3. 26 CFR 1.652(a)-2 - Distributions in excess of distributable net income.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ....652(a)-2 Distributions in excess of distributable net income. If the amount of income required to be... 26 Internal Revenue 8 2010-04-01 2010-04-01 false Distributions in excess of distributable net income. 1.652(a)-2 Section 1.652(a)-2 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF...

  4. Distributions of the interplanetary magnetic field revisited

    NASA Technical Reports Server (NTRS)

    Feynman, Joan; Ruzmaikin, Alexander

    1994-01-01

    The adequacy of the power spectrum to characterize the variations of a parameter depends on whether or not the parameter has a Gaussian distribution. We here perform very simple tests of Gaussianity on the distribution. We here perform very simple tests of Gaussianity on the distributions of the magnitudes of the interplanetary magnetic field, and on the distributions of the components; that is, we find the first four cumulants of the distributions (mean, variance, skewness, and kurtosis) and their solar cycle variations. We find, consistent with other recent analyses, that the traditional distributions of the 1-hour averaged magnitude are not distributed normally or lognomally as has often been assumed and the 1-hour averaged z component is found to have a nonzero kurtosis. Thus the power spectrum is insufficient to completely characterize these variations and polyspectra are needed. We have isolated variations in the 1/f frequency region of the spectrum and show that the distributions of the magnitudes have nonzero skewness and kurtosis, the magnitudes are not distributed lognormally, and the distributions of the components have nonzero kurtosis. Thus higher-order spectra are again needed for a full characterization.

  5. Non-Gaussian Photon Probability Distribution

    NASA Astrophysics Data System (ADS)

    Solomon, Benjamin T.

    2010-01-01

    This paper investigates the axiom that the photon's probability distribution is a Gaussian distribution. The Airy disc empirical evidence shows that the best fit, if not exact, distribution is a modified Gamma mΓ distribution (whose parameters are α = r, βr/√u ) in the plane orthogonal to the motion of the photon. This modified Gamma distribution is then used to reconstruct the probability distributions along the hypotenuse from the pinhole, arc from the pinhole, and a line parallel to photon motion. This reconstruction shows that the photon's probability distribution is not a Gaussian function. However, under certain conditions, the distribution can appear to be Normal, thereby accounting for the success of quantum mechanics. This modified Gamma distribution changes with the shape of objects around it and thus explains how the observer alters the observation. This property therefore places additional constraints to quantum entanglement experiments. This paper shows that photon interaction is a multi-phenomena effect consisting of the probability to interact Pi, the probabilistic function and the ability to interact Ai, the electromagnetic function. Splitting the probability function Pi from the electromagnetic function Ai enables the investigation of the photon behavior from a purely probabilistic Pi perspective. The Probabilistic Interaction Hypothesis is proposed as a consistent method for handling the two different phenomena, the probability function Pi and the ability to interact Ai, thus redefining radiation shielding, stealth or cloaking, and invisibility as different effects of a single phenomenon Pi of the photon probability distribution. Sub wavelength photon behavior is successfully modeled as a multi-phenomena behavior. The Probabilistic Interaction Hypothesis provides a good fit to Otoshi's (1972) microwave shielding, Schurig et al. (2006) microwave cloaking, and Oulton et al. (2008) sub wavelength confinement; thereby providing a strong case that

  6. Sample-Based Vegetation Distribution Information Synthesis.

    PubMed

    Xu, Chanchan; Yang, Gang; Yang, Meng

    2015-01-01

    In constructing and visualizing a virtual three-dimensional forest scene, we must first obtain the vegetation distribution, namely, the location of each plant in the forest. Because the forest contains a large number of plants, the distribution of each plant is difficult to obtain from actual measurement methods. Random approaches are used as common solutions to simulate a forest distribution but fail to reflect the specific biological arrangements among types of plants. Observations show that plants in the forest tend to generate particular distribution patterns due to growth competition and specific habitats. This pattern, which represents a local feature in the distribution and occurs repeatedly in the forest, is in line with the "locality" and "static" characteristics in the "texture data", making it possible to use a sample-based texture synthesis strategy to build the distribution. We propose a vegetation distribution data generation method that uses sample-based vector pattern synthesis. A sample forest stand is obtained first and recorded as a two-dimensional vector-element distribution pattern. Next, the large-scale vegetation distribution pattern is synthesized automatically using the proposed vector pattern synthesis algorithm. The synthesized distribution pattern resembles the sample pattern in the distribution features. The vector pattern synthesis algorithm proposed in this paper adopts a neighborhood comparison technique based on histogram matching, which makes it efficient and easy to implement. Experiments show that the distribution pattern synthesized with this method can sufficiently preserve the features of the sample distribution pattern, making our method meaningful for constructing realistic forest scenes.

  7. Global Distribution of Pyrogenic Carbon

    NASA Astrophysics Data System (ADS)

    Reisser, Moritz; Abiven, Samuel; Schmidt, Michael W. I.

    2016-04-01

    Pyrogenic Carbon (PyC) is ubiquitous in the environment and represents presumably one of the most stable compounds of the total organic carbon. Due to its persistence in the soil, it might play an important role in the global carbon cycle. In order to model future CO2 emissions from soils it is thus crucial to know where and how much of PyC exists on a global scale. Yet, only rough estimates for global PyC stocks in soils could be made, and even less is known about the distribution across ecosystems. Therefore we propose here literature analysis of data on PyC concentrations and stocks worldwide. We extracted PyC values in soils from the literature (n = 600) and analysed the percentage of PyC in the soil organic carbon (SOC) as a function of climate (temperature, precipitation), soil parameters (pH, clay content), fire characteristics (fire frequency and fire regime) and land use. Overall, the average contribution of PyC to SOC was 13 %, ranging from 0.1 % up to 60 %. We observed that the PyC content was significantly higher with high clay content, higher pH, and in cultivated land as compared to forest and grassland. We did not observe any relationships between fire activity, frequency or intensity and PyC % at a global scale. When the fire regime was monitored on site (only 12 % of the data we collected), we observed higher PyC concentrations with higher fire frequencies. We hypothesise that the resolution of global fire datasets is neither temporally nor spatially high enough to explain the very local fire history of the soil samples. Data points were not homogeneously distributed on the globe, but rather aggregated in places like Central Europe, the Russian Steppe or North America. Therefore, a global interpolation is not directly possible. We modelled PyC concentrations, based on the five most significant parameters, which were clay content, pH, mean annual temperature and precipitation as well as land use. We then predicted worldwide PyC using global datasets

  8. A distributed program composition system

    NASA Technical Reports Server (NTRS)

    Brown, Robert L.

    1989-01-01

    A graphical technique for creating distributed computer programs is investigated and a prototype implementation is described which serves as a testbed for the concepts. The type of programs under examination is restricted to those comprising relatively heavyweight parts that intercommunicate by passing messages of typed objects. Such programs are often presented visually as a directed graph with computer program parts as the nodes and communication channels as the edges. This class of programs, called parts-based programs, is not well supported by existing computer systems; much manual work is required to describe the program to the system, establish the communication paths, accommodate the heterogeneity of data types, and to locate the parts of the program on the various systems involved. The work described solves most of these problems by providing an interface for describing parts-based programs in this class in a way that closely models the way programmers think about them: using sketches of diagraphs. Program parts, the computational modes of the larger program system are categorized in libraries and are accessed with browsers. The process of programming has the programmer draw the program graph interactively. Heterogeneity is automatically accommodated by the insertion of type translators where necessary between the parts. Many decisions are necessary in the creation of a comprehensive tool for interactive creation of programs in this class. Possibilities are explored and the issues behind such decisions are presented. An approach to program composition is described, not a carefully implemented programming environment. However, a prototype implementation is described that can demonstrate the ideas presented.

  9. Generalized parton distributions at CLAS

    SciTech Connect

    Silvia Pisano

    2010-11-01

    The understanding of the hadron structure in terms of QCD degrees of freedom is one of the main challenges of hadron physics. Indeed, despite the large amount of theoretical and experimental activity devoted to the subject in the last years, a full comprehension of mesons and baryons in terms of quark and gluon fields is still lacking. In order to operate a more detailed investigation of the hadron structure, new quantities have been introduced ten years ago, the Generalized Parton Distributions (GPDs), defined as bilocal, off-forward matrix elements of quark and gluon operators. From an experimental point of view, GPDs are accessible through two main processes: Deeply Virtual Compton Scattering (DVCS) and Deeply Virtual Meson Electroproduction (DVMP). Depending on the polarization degrees of freedom acting in the process (like, for example, the simultaneous presence of a polarization in the beam and in the target, or the usage of a polarized beam with an unpolarized target), various combinations of GPDs can be accessed. In the case of DVCS, for example, the measurement of the Single Spin Asymmetry of processes like View the MathML source – realized by using a longitudinally polarized target - gives access to a combination of the GDPs H and H̃. The CEBAF Large Acceptance Spectrometer (CLAS) installed in the Hall-B at JLab, is particularly suited for the extraction of these quantities. Its large acceptance implies a good capability in the reconstruction of exclusive final states, allowing the investigation of the aforementioned processes in a wide range of kinematics. In this presentation, an overview of the main GPD measurements performed by CLAS will be given. In particular, the first DVCS measurements realized both with unpolarized and polarized target, together with the measurements of some exclusive meson electroproduction processes, will be described.

  10. Security of Quantum Key Distribution

    NASA Astrophysics Data System (ADS)

    Lütkenhaus, Norbert

    2007-03-01

    Quantum Key Distribution (QKD) is the most advanced application of Quantum Information Science. It allows extending secret keys over some distances in such a way that the security of the resulting key material can be guaranteed by the laws of quantum mechanics. In contrast to presently used encryption techniques, the security of QKD can be proven in terms of information-theoretic measures. The resulting key can then be used for many tasks, including exchanging secret messages. QKD has been developed in the language of abstract two-level systems, the qubits. They cannot be easily implemented in optical signals. It took some time to bring the protocols and theory of QKD to the point where they fit to the realities of fiber-optical or free-space applications, including lossy channels. Today, QKD schemes can be implemented reliably using standard off-the-shelf components. Information theoretic security is a theoretical concept. Naturally, it is impossible to demonstrate directly that a given experimental set-up indeed creates a secret key. What one can do is to show that the experiment can give data within a certain parameters regime, such as error rate and loss rate, for which a security proof exists. I will discuss what parameter regime gives provable secure key and which parameter regime cannot lead to secret key. It is desirable to prove `unconditional security,' as it is termed in the world of classical cryptography: no assumption is made about the attacks of an eavesdropper on the quantum channel. However, one has to assume that the signal structure and the measurement device are correctly described by the adopted model and that no eavesdropper can intrude the sender or receiver unit. In this talk I will briefly introduce the concept of QKD and optical implementations. Especially I will discuss security aspects of modern approaches of QKD schemes that allow us to increase the covered distance and the achievable rate.

  11. Computer security in DOE distributed computing systems

    SciTech Connect

    Hunteman, W.J.

    1990-01-01

    The modernization of DOE facilities amid limited funding is creating pressure on DOE facilities to find innovative approaches to their daily activities. Distributed computing systems are becoming cost-effective solutions to improved productivity. This paper defines and describes typical distributed computing systems in the DOE. The special computer security problems present in distributed computing systems are identified and compared with traditional computer systems. The existing DOE computer security policy supports only basic networks and traditional computer systems and does not address distributed computing systems. A review of the existing policy requirements is followed by an analysis of the policy as it applies to distributed computing systems. Suggested changes in the DOE computer security policy are identified and discussed. The long lead time in updating DOE policy will require guidelines for applying the existing policy to distributed systems. Some possible interim approaches are identified and discussed. 2 refs.

  12. Characterizing maximally singular phase-space distributions

    NASA Astrophysics Data System (ADS)

    Sperling, J.

    2016-07-01

    Phase-space distributions are widely applied in quantum optics to access the nonclassical features of radiations fields. In particular, the inability to interpret the Glauber-Sudarshan distribution in terms of a classical probability density is the fundamental benchmark for quantum light. However, this phase-space distribution cannot be directly reconstructed for arbitrary states, because of its singular behavior. In this work, we perform a characterization of the Glauber-Sudarshan representation in terms of distribution theory. We address important features of such distributions: (i) the maximal degree of their singularities is studied, (ii) the ambiguity of representation is shown, and (iii) their dual space for nonclassicality tests is specified. In this view, we reconsider the methods for regularizing the Glauber-Sudarshan distribution for verifying its nonclassicality. This treatment is supported with comprehensive examples and counterexamples.

  13. A maximum entropy framework for nonexponential distributions.

    PubMed

    Peterson, Jack; Dixit, Purushottam D; Dill, Ken A

    2013-12-17

    Probability distributions having power-law tails are observed in a broad range of social, economic, and biological systems. We describe here a potentially useful common framework. We derive distribution functions for situations in which a "joiner particle" k pays some form of price to enter a community of size , where costs are subject to economies of scale. Maximizing the Boltzmann-Gibbs-Shannon entropy subject to this energy-like constraint predicts a distribution having a power-law tail; it reduces to the Boltzmann distribution in the absence of economies of scale. We show that the predicted function gives excellent fits to 13 different distribution functions, ranging from friendship links in social networks, to protein-protein interactions, to the severity of terrorist attacks. This approach may give useful insights into when to expect power-law distributions in the natural and social sciences. PMID:24297895

  14. Electron butterfly distribution modulation by magnetosonic waves

    NASA Astrophysics Data System (ADS)

    Maldonado, Armando A.; Chen, Lunjin; Claudepierre, Seth G.; Bortnik, Jacob; Thorne, Richard M.; Spence, Harlan

    2016-04-01

    The butterfly pitch angle distribution is observed as a dip in an otherwise normal distribution of electrons centered about αeq=90°. During storm times, the formation of the butterfly distribution on the nightside magnetosphere has been attributed to L shell splitting combined with magnetopause shadowing and strong positive radial flux gradients. It has been shown that this distribution can be caused by combined chorus and magnetosonic wave scattering where the two waves work together but at different local times. Presented in our study is an event on 21 August 2013, using Van Allen Probe measurements, where a butterfly distribution formation is modulated by local magnetosonic coherent magnetosonic waves intensity. Transition from normal to butterfly distributions coincides with rising magnetosonic wave intensity while an opposite transition occurs when wave intensity diminishes. We propose that bounce resonance with waves is the underlying process responsible for such rapid modulation, which is confirmed by our test particle simulation.

  15. Bilateral Trade Flows and Income Distribution Similarity.

    PubMed

    Martínez-Zarzoso, Inmaculada; Vollmer, Sebastian

    2016-01-01

    Current models of bilateral trade neglect the effects of income distribution. This paper addresses the issue by accounting for non-homothetic consumer preferences and hence investigating the role of income distribution in the context of the gravity model of trade. A theoretically justified gravity model is estimated for disaggregated trade data (Dollar volume is used as dependent variable) using a sample of 104 exporters and 108 importers for 1980-2003 to achieve two main goals. We define and calculate new measures of income distribution similarity and empirically confirm that greater similarity of income distribution between countries implies more trade. Using distribution-based measures as a proxy for demand similarities in gravity models, we find consistent and robust support for the hypothesis that countries with more similar income-distributions trade more with each other. The hypothesis is also confirmed at disaggregated level for differentiated product categories.

  16. Bilateral Trade Flows and Income Distribution Similarity

    PubMed Central

    2016-01-01

    Current models of bilateral trade neglect the effects of income distribution. This paper addresses the issue by accounting for non-homothetic consumer preferences and hence investigating the role of income distribution in the context of the gravity model of trade. A theoretically justified gravity model is estimated for disaggregated trade data (Dollar volume is used as dependent variable) using a sample of 104 exporters and 108 importers for 1980–2003 to achieve two main goals. We define and calculate new measures of income distribution similarity and empirically confirm that greater similarity of income distribution between countries implies more trade. Using distribution-based measures as a proxy for demand similarities in gravity models, we find consistent and robust support for the hypothesis that countries with more similar income-distributions trade more with each other. The hypothesis is also confirmed at disaggregated level for differentiated product categories. PMID:27137462

  17. Bilateral Trade Flows and Income Distribution Similarity.

    PubMed

    Martínez-Zarzoso, Inmaculada; Vollmer, Sebastian

    2016-01-01

    Current models of bilateral trade neglect the effects of income distribution. This paper addresses the issue by accounting for non-homothetic consumer preferences and hence investigating the role of income distribution in the context of the gravity model of trade. A theoretically justified gravity model is estimated for disaggregated trade data (Dollar volume is used as dependent variable) using a sample of 104 exporters and 108 importers for 1980-2003 to achieve two main goals. We define and calculate new measures of income distribution similarity and empirically confirm that greater similarity of income distribution between countries implies more trade. Using distribution-based measures as a proxy for demand similarities in gravity models, we find consistent and robust support for the hypothesis that countries with more similar income-distributions trade more with each other. The hypothesis is also confirmed at disaggregated level for differentiated product categories. PMID:27137462

  18. A maximum entropy framework for nonexponential distributions

    PubMed Central

    Peterson, Jack; Dixit, Purushottam D.; Dill, Ken A.

    2013-01-01

    Probability distributions having power-law tails are observed in a broad range of social, economic, and biological systems. We describe here a potentially useful common framework. We derive distribution functions for situations in which a “joiner particle” k pays some form of price to enter a community of size , where costs are subject to economies of scale. Maximizing the Boltzmann–Gibbs–Shannon entropy subject to this energy-like constraint predicts a distribution having a power-law tail; it reduces to the Boltzmann distribution in the absence of economies of scale. We show that the predicted function gives excellent fits to 13 different distribution functions, ranging from friendship links in social networks, to protein–protein interactions, to the severity of terrorist attacks. This approach may give useful insights into when to expect power-law distributions in the natural and social sciences. PMID:24297895

  19. Intelligent Systems for Power Management and Distribution

    NASA Technical Reports Server (NTRS)

    Button, Robert M.

    2002-01-01

    The motivation behind an advanced technology program to develop intelligent power management and distribution (PMAD) systems is described. The program concentrates on developing digital control and distributed processing algorithms for PMAD components and systems to improve their size, weight, efficiency, and reliability. Specific areas of research in developing intelligent DC-DC converters and distributed switchgear are described. Results from recent development efforts are presented along with expected future benefits to the overall PMAD system performance.

  20. Unstable resonators with a distributed focusing gain.

    PubMed

    Ferguson, T R

    1994-08-20

    The geometrical optics approximation is used to form a model of axisymmetric unstable resonators having distributed focus, gain, and loss. A tapered reflectivity feedback mirror is included. The rate equations for propagation through the focusing gain medium are derived. A unique grid is found for propagation without interpolation along eigenrays in each direction. Numerical examples show the effects of distributed gain and focus on the axial and transverse intensity distributions. PMID:20935986