WorldWideScience

Sample records for satellite isis network

  1. Interim Service ISDN Satellite (ISIS) network model for advanced satellite designs and experiments

    Science.gov (United States)

    Pepin, Gerard R.; Hager, E. Paul

    1991-01-01

    The Interim Service Integrated Services Digital Network (ISDN) Satellite (ISIS) Network Model for Advanced Satellite Designs and Experiments describes a model suitable for discrete event simulations. A top-down model design uses the Advanced Communications Technology Satellite (ACTS) as its basis. The ISDN modeling abstractions are added to permit the determination and performance for the NASA Satellite Communications Research (SCAR) Program.

  2. Interim Service ISDN Satellite (ISIS) simulator development for advanced satellite designs and experiments

    Science.gov (United States)

    Pepin, Gerard R.

    1992-01-01

    The simulation development associated with the network models of both the Interim Service Integrated Services Digital Network (ISDN) Satellite (ISIS) and the Full Service ISDN Satellite (FSIS) architectures is documented. The ISIS Network Model design represents satellite systems like the Advanced Communications Technology Satellite (ACTS) orbiting switch. The FSIS architecture, the ultimate aim of this element of the Satellite Communications Applications Research (SCAR) Program, moves all control and switching functions on-board the next generation ISDN communications satellite. The technical and operational parameters for the advanced ISDN communications satellite design will be obtained from the simulation of ISIS and FSIS engineering software models for their major subsystems. Discrete event simulation experiments will be performed with these models using various traffic scenarios, design parameters, and operational procedures. The data from these simulations will be used to determine the engineering parameters for the advanced ISDN communications satellite.

  3. ISIS Electronics Flying on Korean LEO Satellites

    Science.gov (United States)

    Remy, S.; Mosset, E.; Park, Sungwoo

    2014-08-01

    Saft (Defense & Space, France), ASP (Advanced Space Power, Germany) and KARI (Korean Aerospace Research Institute, South Korea) developed an autonomous battery management system to carry out cell packages balancing, by-pass system activation and cell package discharge after failure detection. This high reliability electronics called ISIS (Intelligent Surveillance Integrated System) has been designed, tested and qualified in the frame of the Kompsat-3, Kompsat-5 and Kompsat-3A large LEO Korean KARI Satellites. Kompsat-3 and 3A (4.8 kWh battery) and Kompsat-5 (5.2 kWh battery equipped with a demanding imaging radar system) are powered during daily sun eclipses with respectively one 4P12S or 4P13S VES100 li-ion batteries managed by ISIS system.

  4. Interim Service ISDN Satellite (ISIS) hardware experiment development for advanced ISDN satellite designs and experiments

    Science.gov (United States)

    Pepin, Gerard R.

    1992-01-01

    The Interim Service Integrated Service Digital Network (ISDN) Satellite (ISIS) Hardware Experiment Development for Advanced Satellite Designs describes the development of the ISDN Satellite Terminal Adapter (ISTA) capable of translating ISDN protocol traffic into Time Division Multiple Access (TDMA) signals for use by a communications satellite. The ISTA connects the Type 1 Network Termination (NT1) via the U-interface on the line termination side of the CPE to the RS-499 interface for satellite uplink. The same ISTA converts in the opposite direction the RS-499 to U-interface data with a simple switch setting.

  5. Interim Service ISDN Satellite (ISIS) hardware experiment design for advanced ISDN satellite design and experiments

    Science.gov (United States)

    Pepin, Gerard R.

    1992-01-01

    The Interim Service Integrated Services Digital Network (ISDN) Satellite (ISIS) Hardware Experiment Design for Advanced Satellite Designs describes the design of the ISDN Satellite Terminal Adapter (ISTA) capable of translating ISDN protocol traffic into time division multiple access (TDMA) signals for use by a communications satellite. The ISTA connects the Type 1 Network Termination (NT1) via the U-interface on the line termination side of the CPE to the V.35 interface for satellite uplink. The same ISTA converts in the opposite direction the V.35 to U-interface data with a simple switch setting.

  6. Whistler-triggered emissions observed by ISIS satellites

    Science.gov (United States)

    Nakamura, Y.; Ondoh, T.

    1989-01-01

    A statistical examination has been conducted of the ducted and nonducted whistler-triggered emissions (WTEs) observed by the ISIS satellites in the 1979-1981 period. Most WTEs are observed with simultaneous lower hybrid resonance in the topside ionosphere. The VLF emissions triggered by ducted whistlers frequently occur at L of 2-3, while those triggered by nonducted whistlers occur in the wider latitudinal regions at L of 2.2-4.3.

  7. An Application to WIN/ISIS Database on Local Network

    Directory of Open Access Journals (Sweden)

    Robert Lechien

    2005-07-01

    Full Text Available A Translated Article containing an application to how WIN/ISIS database work on local network. It starts with main definitions, and how to install WIN/ISIS on PC, and how to install it on the local network server.

  8. Full Service ISDN Satellite (FSIS) network model for advanced ISDN satellite design and experiments

    Science.gov (United States)

    Pepin, Gerard R.

    1992-01-01

    The Full Service Integrated Services Digital Network (FSIS) network model for advanced satellite designs describes a model suitable for discrete event simulations. A top down model design uses the Advanced Communications Technology Satellite (ACTS) as its basis. The ACTS and the Interim Service ISDN Satellite (ISIS) perform ISDN protocol analyses and switching decisions in the terrestrial domain, whereas FSIS makes all its analyses and decisions on-board the ISDN satellite.

  9. Examining ISIS Support and Opposition Networks on Twitter

    Science.gov (United States)

    2016-01-01

    Kharijites, Kharijites [derogatory term for Sunni extremists] the militants of Daesh dogs of fire dogs of Baghdadi ISIS phrases in the shadow of the...examined the makeup of the Sunni metacommunity and found that Egyptian, Saudi Arabian, and GCC subcommunities serve as core components. In most of these

  10. Effects of the ISIS Recommender System for Navigation Support in Self-Organized Learning Networks

    NARCIS (Netherlands)

    Drachsler, Hendrik; Hummel, Hans; Van den Berg, Bert; Eshuis, Jannes; Waterink, Wim; Nadolski, Rob; Berlanga, Adriana; Boers, Nanda; Koper, Rob

    2008-01-01

    Drachsler, H., Hummel, H. G. K., Van den Berg, B., Eshuis, J., Waterink, W., Nadolski, R., Berlanga, A., Boers, N., & Koper, R. (2008). Effects of the ISIS Recommender System for Navigation Support in Self-Organized Learning Networks. In M. Kalz, R. Koper, V. Hornung-Prähauser & M. Luckmann (Eds.).

  11. Effects of the ISIS Recommender System for navigation support in self-organised Learning Networks

    NARCIS (Netherlands)

    Drachsler, Hendrik; Hummel, Hans; Van den Berg, Bert; Eshuis, Jannes; Waterink, Wim; Nadolski, Rob; Berlanga, Adriana; Boers, Nanda; Koper, Rob

    2008-01-01

    Drachsler, H., Hummel, H. G. K., Van den Berg, B., Eshuis, J., Berlanga, A., Nadolski, R., Waterink, W., Boers, N., & Koper, R. (2008). Effects of the ISIS Recommender System for navigation support in self-organized Learning Networks. Presentation at the 4th conference Edumedia Conference 2008 Self-

  12. Effects of the ISIS Recommender System for navigation support in self-organised Learning Networks

    NARCIS (Netherlands)

    Drachsler, Hendrik; Hummel, Hans; Van den Berg, Bert; Eshuis, Jannes; Waterink, Wim; Nadolski, Rob; Berlanga, Adriana; Boers, Nanda; Koper, Rob

    2009-01-01

    Drachsler, H., Hummel, H. G. K., Van den Berg, B., Eshuis, J., Waterink, W., Nadolski, R. J., Berlanga, A. J., Boers, N., & Koper, R. (2009). Effects of the ISIS Recommender System for navigation support in self-organised Learning Networks. Journal of Educational Technology and Society, 12(3), 122-1

  13. Effects of the ISIS Recommender System for Navigation Support in Self-Organized Learning Networks

    NARCIS (Netherlands)

    Drachsler, Hendrik; Hummel, Hans; Van den Berg, Bert; Eshuis, Jannes; Waterink, Wim; Nadolski, Rob; Berlanga, Adriana; Boers, Nanda; Koper, Rob

    2008-01-01

    Drachsler, H., Hummel, H. G. K., Van den Berg, B., Eshuis, J., Waterink, W., Nadolski, R., Berlanga, A., Boers, N., & Koper, R. (2008). Effects of the ISIS Recommender System for Navigation Support in Self-Organized Learning Networks. In M. Kalz, R. Koper, V. Hornung-Prähauser & M. Luckmann (Eds.).

  14. Satellite Upper Air Network (SUAN)

    Science.gov (United States)

    Reale, Tony L.; Thorne, Peter

    2004-10-01

    During the past 20 years of NOAA operational polar satellites, it has become evident that a growing problem concerning their utilization in Climate and also Numerical Weather Prediction (NWP) applications are the systematic errors and uncertainties inherent in the satellite measurements. Similar arguments can be made for global radiosonde observations. These uncertainties are often larger than the sensitive signals and processes, that satellite and radiosonde measurements are designed to reveal, particularly in the realm of climate. Possible strategies to quantify and compensate for these problems include the analysis of satellite overlap data and/or available collocations of satellite and ground truth (radiosonde) observations. However, overlap observations are typically not available except in extreme polar regions and current sampling strategies for compiling collocated radiosonde and satellite observations are insufficient, further compounding the inherent uncertainties in the ground-truth radiosonde data. A Satellite Upper Air Network is proposed to provide reference radiosonde launches coincident with operational polar satellite(s) overpass. The SUAN consist of 36 global radiosonde stations sub-sampled from the Global Upper Air Network (GUAN), and is designed to provide a robust, global sample of collocated radiosonde and satellite observations conducive to the monitoring and validation of satellite and radiosonde observations. The routine operation of such a network in conjunction with operational polar satellites would provide a long-term of performance for critical observations of particular importance for climate. The following report presents a candidate network of 36 upper-air sites that could comprise a SUAN. Their selection along with the mutual benefit across the satellite, radiosonde, climate, numerical weather prediction (NWP) and radiative transfer (RT) model areas are discussed.

  15. Multicast Routing in Satellite Network

    Institute of Scientific and Technical Information of China (English)

    郭惠玲; 宋姝; 李磊; 刘志涛; 郭鹏程

    2004-01-01

    There are some problems in the dual-layer satellite MPLs metworks to be composed of LEO and MEO. In order to solve the problems, this paper presents a plan by means of unicast LSP to implement multicast in the dual-layer satellite MPLs networks. It has advantages of saving space and reducing extra charge.

  16. The Institutionalization of Scientific Information: A Scientometric Model (ISI-S Model).

    Science.gov (United States)

    Vinkler, Peter

    2002-01-01

    Introduces a scientometric model (ISI-S model) for describing the institutionalization process of scientific information. ISI-S describes the information and knowledge systems of scientific publications as a global network of interdependent information and knowledge clusters that are dynamically changing by their content and size. (Author/LRW)

  17. Gigabit Satellite Network for NASA's Advanced Communication Technology Satellite (ACTS)

    Science.gov (United States)

    Hoder, Douglas; Bergamo, Marcos

    1996-01-01

    The advanced communication technology satellite (ACTS) gigabit satellite network provides long-haul point-to-point and point-to-multipoint full-duplex SONET services over NASA's ACTS. at rates up to 622 Mbit/s (SONET OC-12), with signal quality comparable to that obtained with terrestrial fiber networks. Data multiplexing over the satellite is accomplished using time-division multiple access (TDMA) techniques coordinated with the switching and beam hopping facilities provided by ACTS. Transmissions through the satellite are protected with Reed-Solomon encoding. providing virtually error-free transmission under most weather conditions. Unique to the system are a TDMA frame structure and satellite synchronization mechanism that allow: (a) very efficient utilization of the satellite capacity: (b) over-the-satellite dosed-loop synchronization of the network in configurations with up to 64 ground stations: and (c) ground station initial acquisition without collisions with existing signalling or data traffic. The user interfaces are compatible with SONET standards, performing the function of conventional SONET multiplexers and. as such. can be: readily integrated with standard SONET fiber-based terrestrial networks. Management of the network is based upon the simple network management protocol (SNMP). and includes an over-the-satellite signalling network and backup terrestrial internet (IP-based) connectivity. A description of the ground stations is also included.

  18. Satellite communications network design and analysis

    CERN Document Server

    Jo, Kenneth Y

    2011-01-01

    This authoritative book provides a thorough understanding of the fundamental concepts of satellite communications (SATCOM) network design and performance assessments. You find discussions on a wide class of SATCOM networks using satellites as core components, as well as coverage key applications in the field. This in-depth resource presents a broad range of critical topics, from geosynchronous Earth orbiting (GEO) satellites and direct broadcast satellite systems, to low Earth orbiting (LEO) satellites, radio standards and protocols.This invaluable reference explains the many specific uses of

  19. Satellite ATM Networks: Architectures and Guidelines Developed

    Science.gov (United States)

    vonDeak, Thomas C.; Yegendu, Ferit

    1999-01-01

    An important element of satellite-supported asynchronous transfer mode (ATM) networking will involve support for the routing and rerouting of active connections. Work published under the auspices of the Telecommunications Industry Association (http://www.tiaonline.org), describes basic architectures and routing protocol issues for satellite ATM (SATATM) networks. The architectures and issues identified will serve as a basis for further development of technical specifications for these SATATM networks. Three ATM network architectures for bent pipe satellites and three ATM network architectures for satellites with onboard ATM switches were developed. The architectures differ from one another in terms of required level of mobility, supported data rates, supported terrestrial interfaces, and onboard processing and switching requirements. The documentation addresses low-, middle-, and geosynchronous-Earth-orbit satellite configurations. The satellite environment may require real-time routing to support the mobility of end devices and nodes of the ATM network itself. This requires the network to be able to reroute active circuits in real time. In addition to supporting mobility, rerouting can also be used to (1) optimize network routing, (2) respond to changing quality-of-service requirements, and (3) provide a fault tolerance mechanism. Traffic management and control functions are necessary in ATM to ensure that the quality-of-service requirements associated with each connection are not violated and also to provide flow and congestion control functions. Functions related to traffic management were identified and described. Most of these traffic management functions will be supported by on-ground ATM switches, but in a hybrid terrestrial-satellite ATM network, some of the traffic management functions may have to be supported by the onboard satellite ATM switch. Future work is planned to examine the tradeoffs of placing traffic management functions onboard a satellite as

  20. Satellite Networks: Architectures, Applications, and Technologies

    Science.gov (United States)

    Bhasin, Kul (Compiler)

    1998-01-01

    Since global satellite networks are moving to the forefront in enhancing the national and global information infrastructures due to communication satellites' unique networking characteristics, a workshop was organized to assess the progress made to date and chart the future. This workshop provided the forum to assess the current state-of-the-art, identify key issues, and highlight the emerging trends in the next-generation architectures, data protocol development, communication interoperability, and applications. Presentations on overview, state-of-the-art in research, development, deployment and applications and future trends on satellite networks are assembled.

  1. An access alternative for mobile satellite networks

    Science.gov (United States)

    Wu, W. W.

    1988-05-01

    Conceptually, this paper discusses strategies of digital satellite communication networks for a very large number of low density traffic stations. These stations can be either aeronautical, land mobile, or maritime. The techniques can be applied to international, domestic, regional, and special purpose satellite networks. The applications can be commercial, scientific, military, emergency, navigational or educational. The key strategy is the use of a non-orthogonal access method, which tolerates overlapping signals. With n being either time or frequency partitions, and with a single overlapping signal allowed, a low cost mobile satellite system can be designed with n squared (n squared + n + 1) number of terminals.

  2. Satellite Tracking Astrometric Network (STAN)

    Science.gov (United States)

    Vecchiato, Alberto; Gai, Mario

    2015-08-01

    The possibility of precise orbit tracking and determination of different types of satellites has been explored for at least some 25 years (Arimoto et al., 1990). Proposals in this sense made use mainly of astrometric observations, but multiple tracking techniques combining transfer and laser ranging was also suggested (Guo et al., 2009; Montojo et al., 2011), with different requirements and performances ranging from $\\sim100$~m to tenths of meters.In this work we explore the possible improvements and a novel implementation of a technique relying on large angle, high precision astrometry from ground for the determination of satellite orbits. The concept is based on combined observation of geostationary satellites and other near-Earth space objects from two or more telescopes, applying the triangulation principle over widely separated regions of the sky. An accuracy of a few $10^{-2}$~m can be attained with 1-meter-class telescopes and a field of vied of some arcminutes.We discuss the feasibility of the technique, some of the implementation aspects, and the limitations imposed by atmospheric turbulence. The potential benefits for satellite orbit control and navigation systems are presented, depending on the number and position of the contributing telescopes.We also discuss the possibility that, by reversing the roles of stars and satellites, the same kind of observations can be used for verification and maintenance of astrometric catalogs.

  3. Future large broadband switched satellite communications networks

    Science.gov (United States)

    Staelin, D. H.; Harvey, R. R.

    1979-01-01

    Critical technical, market, and policy issues relevant to future large broadband switched satellite networks are summarized. Our market projections for the period 1980 to 2000 are compared. Clusters of switched satellites, in lieu of large platforms, etc., are shown to have significant advantages. Analysis of an optimum terrestrial network architecture suggests the proper densities of ground stations and that link reliabilities 99.99% may entail less than a 10% cost premium for diversity protection at 20/30 GHz. These analyses suggest that system costs increase as the 0.6 power of traffic. Cost estimates for nominal 20/30 GHz satellite and ground facilities suggest optimum system configurations might employ satellites with 285 beams, multiple TDMA bands each carrying 256 Mbps, and 16 ft ground station antennas. A nominal development program is outlined.

  4. Congestion control and routing over satellite networks

    Science.gov (United States)

    Cao, Jinhua

    Satellite networks and transmissions find their application in fields of computer communications, telephone communications, television broadcasting, transportation, space situational awareness systems and so on. This thesis mainly focuses on two networking issues affecting satellite networking: network congestion control and network routing optimization. Congestion, which leads to long queueing delays, packet losses or both, is a networking problem that has drawn the attention of many researchers. The goal of congestion control mechanisms is to ensure high bandwidth utilization while avoiding network congestion by regulating the rate at which traffic sources inject packets into a network. In this thesis, we propose a stable congestion controller using data-driven, safe switching control theory to improve the dynamic performance of satellite Transmission Control Protocol/Active Queue Management (TCP/AQM) networks. First, the stable region of the Proportional-Integral (PI) parameters for a nominal model is explored. Then, a PI controller, whose parameters are adaptively tuned by switching among members of a given candidate set, using observed plant data, is presented and compared with some classical AQM policy examples, such as Random Early Detection (RED) and fixed PI control. A new cost detectable switching law with an interval cost function switching algorithm, which improves the performance and also saves the computational cost, is developed and compared with a law commonly used in the switching control literature. Finite-gain stability of the system is proved. A fuzzy logic PI controller is incorporated as a special candidate to achieve good performance at all nominal points with the available set of candidate controllers. Simulations are presented to validate the theory. An effocient routing algorithm plays a key role in optimizing network resources. In this thesis, we briefly analyze Low Earth Orbit (LEO) satellite networks, review the Cross Entropy (CE

  5. Simulator design for advanced ISDN satellite design and experiments

    Science.gov (United States)

    Pepin, Gerald R.

    1992-01-01

    This simulation design task completion report documents the simulation techniques associated with the network models of both the Interim Service ISDN (integrated services digital network) Satellite (ISIS) and the Full Service ISDN Satellite (FSIS) architectures. The ISIS network model design represents satellite systems like the Advanced Communication Technology Satellite (ACTS) orbiting switch. The FSIS architecture, the ultimate aim of this element of the Satellite Communications Applications Research (SCAR) program, moves all control and switching functions on-board the next generation ISDN communication satellite. The technical and operational parameters for the advanced ISDN communications satellite design will be obtained from the simulation of ISIS and FSIS engineering software models for their major subsystems. Discrete events simulation experiments will be performed with these models using various traffic scenarios, design parameters and operational procedures. The data from these simulations will be used to determine the engineering parameters for the advanced ISDN communications satellite.

  6. Design and analysis of the satellite laser communications network

    Science.gov (United States)

    Ren, Pei-an; Qian, Fengchen; Liu, Qiang; Jin, Linlin

    2015-02-01

    A satellite laser communications network structure with two layers and multiple domains has been proposed, which performance has been simulated by OPENT. To simulation, we design several OPNET models of the network's components based on a satellite constellation with two layers and multiple domains, as network model, node model, MAC layer protocol and optical antenna model. The network model consists of core layer and access layer. The core network consists of four geostationary orbit (GEO) satellites which are uniformly distributed in the geostationary orbit. The access network consists of 6 low Earth orbit (LEO) satellites which is the walker delta (walk-δ) constellation with three orbit planes. In access layer, each plane has two satellites, and the constellation is stably. The satellite constellation presented for space laser network can meet the demand of coverage in the middle and low latitude by a few satellites. Also several terminal device models such as the space laser transmitter, receiver, protocol layer module and optical antenna have been designed according to the inter-satellite links in different orbits t from GEO to LEO or GEO to ground. The influence to network of different transmitting throughput, receiving throughput, network protocol and average time delay are simulated. Simulation results of network coverage, connectivity and traffic load performance in different scenes show that the satellite laser network presented by the paper can be fit for high-speed satellite communications. Such analysis can provide effective reference for the research of satellite laser networking and communication protocol.

  7. Network Configuration Analysis for Formation Flying Satellites

    Science.gov (United States)

    Knoblock, Eric J.; Wallett, Thomas M.; Konangi, Vijay K.; Bhasin, Kul B.

    2001-01-01

    The performance of two networks to support autonomous multi-spacecraft formation flying systems is presented. Both systems are comprised of a ten-satellite formation, with one of the satellites designated as the central or 'mother ship.' All data is routed through the mother ship to the terrestrial network. The first system uses a TCP/EP over ATM protocol architecture within the formation, and the second system uses the IEEE 802.11 protocol architecture within the formation. The simulations consist of file transfers using either the File Transfer Protocol (FTP) or the Simple Automatic File Exchange (SAFE) Protocol. The results compare the IP queuing delay, IP queue size and IP processing delay at the mother ship as well as end-to-end delay for both systems. In all cases, using IEEE 802.11 within the formation yields less delay. Also, the throughput exhibited by SAFE is better than FTP.

  8. Networks for Autonomous Formation Flying Satellite Systems

    Science.gov (United States)

    Knoblock, Eric J.; Konangi, Vijay K.; Wallett, Thomas M.; Bhasin, Kul B.

    2001-01-01

    The performance of three communications networks to support autonomous multi-spacecraft formation flying systems is presented. All systems are comprised of a ten-satellite formation arranged in a star topology, with one of the satellites designated as the central or "mother ship." All data is routed through the mother ship to the terrestrial network. The first system uses a TCP/lP over ATM protocol architecture within the formation the second system uses the IEEE 802.11 protocol architecture within the formation and the last system uses both of the previous architectures with a constellation of geosynchronous satellites serving as an intermediate point-of-contact between the formation and the terrestrial network. The simulations consist of file transfers using either the File Transfer Protocol (FTP) or the Simple Automatic File Exchange (SAFE) Protocol. The results compare the IF queuing delay, and IP processing delay at the mother ship as well as application-level round-trip time for both systems, In all cases, using IEEE 802.11 within the formation yields less delay. Also, the throughput exhibited by SAFE is better than FTP.

  9. Oil Federalism In Iraq: Resource Curse, Patronage Networks and Stability. Case Studies of Baghdad, Kurdistan and the Advent of ISIS

    Science.gov (United States)

    Wahab, Bilal A.

    Petroleum wealth is the lifeblood of Iraq, with the potential to promote prosperity, or become a curse that destabilizes the country and interrupts its economic and political development. The management and sharing of petroleum wealth has been at the center of economic, political and security developments in Iraq since the country's invasion in 2003. This study analyzes Iraq's experiment with petrofederalism, the influence of different actors (e.g. international oil companies and ISIS), and the emergence of Iraqi Kurdistan as a petroregion. Using case study method, it demonstrates how patronage politics exacerbated resource curse in Iraq and resulted in instability.

  10. LTE Adaptation for Mobile Broadband Satellite Networks

    Directory of Open Access Journals (Sweden)

    Bastia Francesco

    2009-01-01

    Full Text Available One of the key factors for the successful deployment of mobile satellite systems in 4G networks is the maximization of the technology commonalities with the terrestrial systems. An effective way of achieving this objective consists in considering the terrestrial radio interface as the baseline for the satellite radio interface. Since the 3GPP Long Term Evolution (LTE standard will be one of the main players in the 4G scenario, along with other emerging technologies, such as mobile WiMAX; this paper analyzes the possible applicability of the 3GPP LTE interface to satellite transmission, presenting several enabling techniques for this adaptation. In particular, we propose the introduction of an inter-TTI interleaving technique that exploits the existing H-ARQ facilities provided by the LTE physical layer, the use of PAPR reduction techniques to increase the resilience of the OFDM waveform to non linear distortion, and the design of the sequences for Random Access, taking into account the requirements deriving from the large round trip times. The outcomes of this analysis show that, with the required proposed enablers, it is possible to reuse the existing terrestrial air interface to transmit over the satellite link.

  11. Network coding and its applications to satellite systems

    DEFF Research Database (Denmark)

    Vieira, Fausto; Roetter, Daniel Enrique Lucani

    2015-01-01

    Network coding has its roots in information theory where it was initially proposed as a way to improve a two-node communication using a (broadcasting) relay. For this theoretical construct, a satellite communications system was proposed as an illustrative example, where the relay node would...... be a satellite covering the two nodes. The benefits in terms of throughput, resilience, and flexibility of network coding are quite relevant for wireless networks in general, and for satellite systems in particular. This chapter presents some of the basics in network coding, as well as an overview of specific...... scenarios where network coding provides a significant improvement compared to existing solutions, for example, in broadcast and multicast satellite networks, hybrid satellite-terrestrial networks, and broadband multibeam satellites. The chapter also compares coding perspectives and revisits the layered...

  12. Network coding and its applications to satellite systems

    DEFF Research Database (Denmark)

    Vieira, Fausto; Roetter, Daniel Enrique Lucani

    2015-01-01

    Network coding has its roots in information theory where it was initially proposed as a way to improve a two-node communication using a (broadcasting) relay. For this theoretical construct, a satellite communications system was proposed as an illustrative example, where the relay node would...... be a satellite covering the two nodes. The benefits in terms of throughput, resilience, and flexibility of network coding are quite relevant for wireless networks in general, and for satellite systems in particular. This chapter presents some of the basics in network coding, as well as an overview of specific...... scenarios where network coding provides a significant improvement compared to existing solutions, for example, in broadcast and multicast satellite networks, hybrid satellite-terrestrial networks, and broadband multibeam satellites. The chapter also compares coding perspectives and revisits the layered...

  13. 47 CFR 76.122 - Satellite network non-duplication.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Satellite network non-duplication. 76.122... MULTICHANNEL VIDEO AND CABLE TELEVISION SERVICE Network Non-duplication Protection, Syndicated Exclusivity and Sports Blackout § 76.122 Satellite network non-duplication. (a) Upon receiving notification pursuant...

  14. Integrated Adaptive Analysis and Visualization of Satellite Network Data Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop a system that enables integrated and adaptive analysis and visualization of satellite network management data. Integrated analysis and...

  15. Satellite communications for the next generation telecommunication services and networks

    Science.gov (United States)

    Chitre, D. M.

    1991-01-01

    Satellite communications can play an important role in provisioning the next-generation telecommunication services and networks, provided the protocols specifying these services and networks are satellite-compatible and the satellite subnetworks, consisting of earth stations interconnected by the processor and the switch on board the satellite, interwork effectively with the terrestrial networks. The specific parameters and procedures of frame relay and broadband integrated services digital network (B-ISDN) protocols which are impacted by a satellite delay. Congestion and resource management functions for frame relay and B-ISDN are discussed in detail, describing the division of these functions between earth stations and on board the satellite. Specific onboard and ground functions are identified as potential candidates for their implementation via neural network technology.

  16. Study on Service Level Management in Integrated Satellite Information Network

    Institute of Scientific and Technical Information of China (English)

    SHANG Rui-qiang; ZHAO Jian-li; WANG Guang-xing

    2005-01-01

    Integrated Satellite Information Network (ISIN) includes those nodes in space and those on ground. It is the way to realize the fusion of satellite communication and traditional network technology. A satellite network management system based on Multiplex Network Management Protocol (MNMP) has accomplished traditional management, such as configuration, performance and fault management. An architecture of Service Level Management (SLM) in ISIN is proposed, and a service topology management and Service Level Agreement (SLA) are deeply researched. At last, service security and fault management are briefly discussed, and a simulation system is accomplished.

  17. Inside ISIS II

    CERN Multimedia

    1981-01-01

    ISIS stands for Identification of Secondaries by Ionization Sampling. It was a drift chamber with an active volume of about 40 m3 built by Oxford University as a particle identifier for the European Hybrid Spectrometer (EHS). The photo shows the electrostatic grading structure and the central anode-wire plane, with Roger Giles standing just under it (Annual Report 1981 p. 57, Fig. 4). ISIS-II differed from the prototype ISIS-I only in the depth of the track (4 m instead of 1 m) thus extending the momentum range for particle identification to 50 GeV/c. See Nucl. Instr. and Meth. 224 (1984) 396, and Nucl. Instr. and Meth. 258 (1987) 26.

  18. Packet routing algorithm for polar orbit LEO satellite constellation network

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Broadband satellite networks are capable of providing global coverage and support various services. The networks constructed by Low Earth Orbit (LEO) satellite constellations have attracted great interests because of their short round-trip delays and wide bandwidths. A challenging problem is to develop a simple and efficient packet routing algorithm for the LEO satellite constellation network. This paper presents a SpiderWeb Topological Network (SWTN) and a distributed packet routing algorithm for the LEO satellite constellation network based on the SWTN. The algorithm gives the minimum propagation delay paths with low computational complexity and requires no routing tables, which is practical for on-board processing. The performance of the algorithm is demonstrated through simulations.

  19. Test using communication satellite for security telecommunication network

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, M.

    1988-01-01

    The authors confirmed by their experiment results that the satellite communication could be practically used for remote monitoring and control in gas distribution systems and data communication not only in emergency but also as the reinforced means of communication network. This report deals with the general description of the security communication network, our experiment of satellite operating system, the results and further plan for the practical application. Their company has started the test on the utilization of a communication satellite (CS-2 Japanese domestic communication satellite) since July, 1984, for the purpose of securing the telecommunication network in case of disaster and applying the satellite communications to data communication suitable for the information age, as for a gas utility industry.

  20. Dynamic Characteristics of Inter-Satellite Links in LEO Networks

    Institute of Scientific and Technical Information of China (English)

    王亮; 张乃通; 温萍萍

    2003-01-01

    To establish an efficient inter-satellite link (ISL) in an LEO network, the effect of geometric characteristics of ISL on the ISLs and the devices on the LEO satellite should be examined. Because of the continuous movement of the LEO satellite, the time-varying behaviours of the ISL's geometric charactersistics continuously change with the changes of the satellite's position on the orbit. These dynamic geometric characteristics of the ISLs are important for ISL's performance analyzing and the design of the devices on the LEO satellite. This paper describes dynamic geometric characteristics of ISL, analyzes the impact of these regulations on the tracking system of the satellite's antenna and the power adjusting system of the satellite's transmitter, with the Iridium system as an example.

  1. Transmission Technique towards Seamless Handover for NGEO Satellite Networks

    Institute of Scientific and Technical Information of China (English)

    Wang LU; Liu Lixiang; Hu Xiaohui

    2011-01-01

    This paper presents a seamless transmission technique for Non-Geostationary Earth Orbit (NGEO) satellite networks.The seamless transmission technique combines the concept of Hop-by-Hop and network coding to alleviate the negative impacts of handovers,high bit error rate,and long delay,and to achieve high throughput and complete delivery in NGEO satellite networks.This network coding algorithm is able to maintain expected small queue size and low decoding latency.Furthermore,the seamless transmission technique applies a novel explicit congestion notification mechanism and can achieve high bandwidth utilization.Various aspects of this seamless transmission technique are evaluated.

  2. Advanced ISDN satellite designs and experiments

    Science.gov (United States)

    Pepin, Gerard R.

    1992-01-01

    The research performed by GTE Government Systems and the University of Colorado in support of the NASA Satellite Communications Applications Research (SCAR) Program is summarized. Two levels of research were undertaken. The first dealt with providing interim services Integrated Services Digital Network (ISDN) satellite (ISIS) capabilities that accented basic rate ISDN with a ground control similar to that of the Advanced Communications Technology Satellite (ACTS). The ISIS Network Model development represents satellite systems like the ACTS orbiting switch. The ultimate aim is to move these ACTS ground control functions on-board the next generation of ISDN communications satellite to provide full-service ISDN satellite (FSIS) capabilities. The technical and operational parameters for the advanced ISDN communications satellite design are obtainable from the simulation of ISIS and FSIS engineering software models of the major subsystems of the ISDN communications satellite architecture. Discrete event simulation experiments would generate data for analysis against NASA SCAR performance measure and the data obtained from the ISDN satellite terminal adapter hardware (ISTA) experiments, also developed in the program. The Basic and Option 1 phases of the program are also described and include the following: literature search, traffic mode, network model, scenario specifications, performance measures definitions, hardware experiment design, hardware experiment development, simulator design, and simulator development.

  3. Advances Made in the Next Generation of Satellite Networks

    Science.gov (United States)

    Bhasin, Kul B.

    1999-01-01

    Because of the unique networking characteristics of communications satellites, global satellite networks are moving to the forefront in enhancing national and global information infrastructures. Simultaneously, broadband data services, which are emerging as the major market driver for future satellite and terrestrial networks, are being widely acknowledged as the foundation for an efficient global information infrastructure. In the past 2 years, various task forces and working groups around the globe have identified pivotal topics and key issues to address if we are to realize such networks in a timely fashion. In response, industry, government, and academia undertook efforts to address these topics and issues. A workshop was organized to provide a forum to assess the current state-of-the-art, identify key issues, and highlight the emerging trends in the next-generation architectures, data protocol development, communication interoperability, and applications. The Satellite Networks: Architectures, Applications, and Technologies Workshop was hosted by the Space Communication Program at the NASA Lewis Research Center in Cleveland, Ohio. Nearly 300 executives and technical experts from academia, industry, and government, representing the United States and eight other countries, attended the event (June 2 to 4, 1998). The program included seven panels and invited sessions and nine breakout sessions in which 42 speakers presented on technical topics. The proceedings covers a wide range of topics: access technology and protocols, architectures and network simulations, asynchronous transfer mode (ATM) over satellite networks, Internet over satellite networks, interoperability experiments and applications, multicasting, NASA interoperability experiment programs, NASA mission applications, and Transmission Control Protocol/Internet Protocol (TCP/IP) over satellite: issues, relevance, and experience.

  4. Distributed Traffic Balancing Routing for LEO Satellite Networks

    Directory of Open Access Journals (Sweden)

    Yong Lu

    2013-11-01

    Full Text Available Satellite networks have been widely investigated both in the business and academia for many years, with many important routing algorithms reported in the literatures. However, fewer existing routing algorithms focus on the trade-off between the routing survivability and the routing computation and storage overheads. Due to topological dynamics, it is difficult to effectively apply the conventional routing protocols such as RIP or OSPF to Low Earth Orbit (LEO satellite networks. According to the virtual topology model based on virtual node, this paper propose a new fully distributed routing protocol for LEO satellite networks, called Distributed Traffic Balancing Routing (DTBR. The proposed protocol not only guarantees the routing survivability and provides the ability of traffic balancing, but also result in few additional computation and storage overheads only deriving from the information flooding of failed satellites. Simulation results demonstrate positive conclusions of our methods.

  5. Dynamic Routing Algorithm for Increasing Robustness in Satellite Networks

    Institute of Scientific and Technical Information of China (English)

    LI Dong-ni; ZHANG Da-kun

    2008-01-01

    In low earth orbit(LEO)and medium earth orbit(MEO)satellite networks,the network topology changes rapidly because of the high relative speed movement of satellites.When some inter-satellite links (ISLs)fail,they can not be repaired in a short time.In order to increase the robustness for LEO/MEO satellite networks,an effective dynamic routing algorithm is proposed.All the routes to a certain node are found by constructing a destination oriented acyclic directed graph(DOADG)with the node as the destination.In this algorithm,multiple routes are provided,loop-free is guaranteed,and as long as the DOADG maintains,it is not necessary to reroute even if some ISLs fail.Simulation results show that comparing to the conventional routing algorithms,it is more efficient and reliable,costs less transmission overhead and converges faster.

  6. Internetworking satellite and local exchange networks for personal communications applications

    Science.gov (United States)

    Wolff, Richard S.; Pinck, Deborah

    1993-01-01

    The demand for personal communications services has shown unprecedented growth, and the next decade and beyond promise an era in which the needs for ubiquitous, transparent and personalized access to information will continue to expand in both scale and scope. The exchange of personalized information is growing from two-way voice to include data communications, electronic messaging and information services, image transfer, video, and interactive multimedia. The emergence of new land-based and satellite-based wireless networks illustrates the expanding scale and trend toward globalization and the need to establish new local exchange and exchange access services to meet the communications needs of people on the move. An important issue is to identify the roles that satellite networking can play in meeting these new communications needs. The unique capabilities of satellites, in providing coverage to large geographic areas, reaching widely dispersed users, for position location determination, and in offering broadcast and multicast services, can complement and extend the capabilities of terrestrial networks. As an initial step in exploring the opportunities afforded by the merger of satellite-based and land-based networks, several experiments utilizing the NASA ACTS satellite and the public switched local exchange network were undertaken to demonstrate the use of satellites in the delivery of personal communications services.

  7. Scenarios and performance measures for advanced ISDN satellite design and experiments

    Science.gov (United States)

    Pepin, Gerard R.

    1991-01-01

    Described here are the contemplated input and expected output for the Interim Service Integrated Services Digital Network (ISDN) Satellite (ISIS) and Full Service ISDN Satellite (FSIS) Models. The discrete event simulations of these models are presented with specific scenarios that stress ISDN satellite parameters. Performance measure criteria are presented for evaluating the advanced ISDN communication satellite designs of the NASA Satellite Communications Research (SCAR) Program.

  8. A Minimum Cost Handover Algorithm for Mobile Satellite Networks

    Institute of Scientific and Technical Information of China (English)

    Zhang Tao; Zhang Jun

    2008-01-01

    For mobile satellite networks,an appropriate handover scheme should be devised to shorten handover delay with optimized application of network resources.By introducing the handover cost model of service,this article proposes a rerouting triggering scheme for path optimization after handover and a new minimum cost handover algorithm for mobile satellite networks.This algorithm ensures the quality of service (QoS) parameters,such as delay,during the handover and minimizes the handover costs.Simulation indicates that this algorithm is superior to other current algorithms in guaranteeing the QoS and decreasing handover costs.

  9. Designing the next phase domestic satellites - A step to communication satellites as intelligent network nodes

    Science.gov (United States)

    Majus, J.

    1982-09-01

    Applications of satellite systems for telecommunication networks are discussed in terms of harmonizing the satellite capabilities with ground-based equipment, and design for the satellites are discussed. Modern network services are becoming increasingly digitized and use optic fiber switching and information transfer. Spaceborne nodes can be used for telephony, television, packet switching, leased lines, and teletex, with reserved sectors for point-to-point communications. Space systems are capable of 100% coverage, while terrestrial systems frequently have utilization rates near 5%, implying that demand-oriented satellite expansion of local systems is the suitable methodology. Technological requirements are explored, including exclusive use of digital processing, flexible flow rates, signal transmission times, and short time availability.

  10. Isis, la Gran Maga

    Directory of Open Access Journals (Sweden)

    Hipólito Pecci Tenrero

    2002-01-01

    Full Text Available La diosa Isis es una de las divinidades más importantes de Egipto, al extenderse por el Mediterráneo continúa manteniendo esta significación. En el texto siguiente se intenta tratar de una forma sucinta como se ha producido esta expansión, la rapidez en conseguir adeptos fuera de Egipto y la influencia no solo dentro de la sociedad, sino también dentro de la política, así como su desaparición final.The goddess Isis is one of the most important divinities of Egypt, on having spread over the Mediterranean she continúes supporting this significance. In the next text one is tried to treat as a succinct form since this expansión, the rapidity has taken place in followers obtained out of Egypt and the influence not only inside the society, but also inside the politics, asweil as his final disappearance.

  11. Next generation communications satellites: multiple access and network studies

    Science.gov (United States)

    Meadows, H. E.; Schwartz, M.; Stern, T. E.; Ganguly, S.; Kraimeche, B.; Matsuo, K.; Gopal, I.

    1982-01-01

    Efficient resource allocation and network design for satellite systems serving heterogeneous user populations with large numbers of small direct-to-user Earth stations are discussed. Focus is on TDMA systems involving a high degree of frequency reuse by means of satellite-switched multiple beams (SSMB) with varying degrees of onboard processing. Algorithms for the efficient utilization of the satellite resources were developed. The effect of skewed traffic, overlapping beams and batched arrivals in packet-switched SSMB systems, integration of stream and bursty traffic, and optimal circuit scheduling in SSMB systems: performance bounds and computational complexity are discussed.

  12. Satellite network robust QoS-aware routing

    CERN Document Server

    Long, Fei

    2014-01-01

    Satellite Network Robust QoS-aware Routing presents a novel routing strategy for satellite networks. This strategy is useful for the design of multi-layered satellite networks as it can greatly reduce the number of time slots in one system cycle. The traffic prediction and engineering approaches make the system robust so that the traffic spikes can be handled effectively. The multi-QoS optimization routing algorithm can satisfy various potential user requirements. Clear and sufficient illustrations are also presented in the book. As the chapters cover the above topics independently, readers from different research backgrounds in constellation design, multi-QoS routing, and traffic engineering can benefit from the book.   Fei Long is a senior engineer at Beijing R&D Center of 54th Research Institute of China Electronics Technology Group Corporation.

  13. Wavelength dimensioning for wavelength-routed WDM satellite network

    Institute of Scientific and Technical Information of China (English)

    Liu Zhe; Guo Wei; Deng Changlin; Hu Weisheng

    2016-01-01

    Internet and broadband applications driven by data traffic demand have become key dri-vers for satellite constellations. The key technology to satisfy the high capacity requirements between satellites is optical satellite networks by means of wavelength division multiplexing inter-satellite links (ISLs) with wavelength routing (WDM-OSN). Due to the limited optical amplifier bandwidth onboard the satellite, it is important to minimize the wavelength requirements to provi-sion requests. However, ISLs should be dynamically established and deleted for each satellite according to its visible satellites. Furthermore, different link assignments will result in different topologies, hence yielding different routings and wavelength assignments. Thus, a perfect match model-based link assignment scheme (LAS-PMM) is proposed to design an appropriate topology such that shorter path could be routed and less wavelengths could be assigned for each ISL along the path. Finally, simulation results show that in comparison to the regular Manhattan street net-work (MSN) topology, wavelength requirements and average end-to-end delay based on the topol-ogy generated by LAS-PMM could be reduced by 24.8%and 12.4%, respectively.

  14. Integration of Quantum Cryptography through Satellite Networks Transmission

    Directory of Open Access Journals (Sweden)

    Skander Aris

    2011-01-01

    Full Text Available Problem statement: The security of the telecommunications satellite has become a crucial issue. The telecommunications can be set using the classical cryptography. But this so-called classical cryptography provides cryptographic security. This means that security is based on the difficulty of some mathematics problems. On the other hand, quantum cryptography provides security without conditions based on the law of quantum physics. This method, called the theoretic information security is evidenced using the theory of information. Approach: In this study, we study whether quantum cryptography can be applied in the frame of the satellite telecommunications network. To do this in our project, we present theories regarding the following issues: Telecommunications Station and Satellite Communication Networks, Quantum Key Distribution, Open Space and Satellites, Analyses in different Scenarios between the Satellite and Earth station. Results: Quantum communications offers many advantages for secure data transmission, in our implementation study, we presented different scenarios of quantum key exchange between satellites and ground stations for possible approach to subsystem with quantum communication in space, capable of generating and detecting entangled photons as well as faint laser pulses. Conclusion: The use of satellites to distribute quantum photon provides a unique solution for long-distance. Moreover, quantum cryptography is a satisfactory solution to improve the safety problem. So, the quantum transmissions are the future of telecommunications.

  15. Satellite link augmentation of ground based packet switched data networks

    Science.gov (United States)

    Farrell, J. B.; McLane, P. J.; Campbell, L. L.

    Use of satellite link augmentation to improve the performance of a packet switched data network is considered. Particular attention is paid to the analysis of two queues in series from the standpoint of time delay. A finite state machine model is used to aid the analysis. The results from the analysis are then used in a flow deviation routing algorithm. This algorithm is applied to study the performance improvement when satellite links are used to augment the Canadian DATAPAC network. The results are backed up by extensive simulations on a digital computer.

  16. Incorporate design of on-board network and inter-satellite network

    Science.gov (United States)

    Li, Bin; You, Zheng; Zhang, Chenguang

    2005-11-01

    In satellite, Data transferring is very important and must be reliable. This paper first introduced an on-board network based on Control Area Network (CAN). As a kind of field bus, CAN is simple and reliable, and has been tested by previous flights. In this paper, the CAN frame is redefined, including the identifier and message data, the addresses for source and destination as well as the frame types. On-board network provides datagram transmission and buffer transmission. Data gram transmission is used to carry out TTC functions, and buffer transmission is used to transfer mass data such as images. Inter-satellite network for satellite formation flying is not designed individually. It takes the advantage of TCP/IP model and inherits and extends on-board network protocols. The inter-satellite network includes a linkage layer, a network layer and a transport layer. There are 8 virtual channels for various space missions or requirements and 4 kinds of services to be selected. The network layer is designed to manage the whole net, calculate and select the route table and gather the network information, while the transport layer mainly routes data, which correspondingly makes it possible for communication between each two nodes. Structures of the linkage frame and transport layer data segment are similar, thus there is no complex packing and unpacking. At last, this paper gives the methods for data conversion between the on-board network and the inter-satellite network.

  17. A Hybrid Satellite-Terrestrial Approach to Aeronautical Communication Networks

    Science.gov (United States)

    Kerczewski, Robert J.; Chomos, Gerald J.; Griner, James H.; Mainger, Steven W.; Martzaklis, Konstantinos S.; Kachmar, Brian A.

    2000-01-01

    Rapid growth in air travel has been projected to continue for the foreseeable future. To maintain a safe and efficient national and global aviation system, significant advances in communications systems supporting aviation are required. Satellites will increasingly play a critical role in the aeronautical communications network. At the same time, current ground-based communications links, primarily very high frequency (VHF), will continue to be employed due to cost advantages and legacy issues. Hence a hybrid satellite-terrestrial network, or group of networks, will emerge. The increased complexity of future aeronautical communications networks dictates that system-level modeling be employed to obtain an optimal system fulfilling a majority of user needs. The NASA Glenn Research Center is investigating the current and potential future state of aeronautical communications, and is developing a simulation and modeling program to research future communications architectures for national and global aeronautical needs. This paper describes the primary requirements, the current infrastructure, and emerging trends of aeronautical communications, including a growing role for satellite communications. The need for a hybrid communications system architecture approach including both satellite and ground-based communications links is explained. Future aeronautical communication network topologies and key issues in simulation and modeling of future aeronautical communications systems are described.

  18. United States Counterterrorism on ISIS

    Directory of Open Access Journals (Sweden)

    ANTON MYNARDY

    2016-05-01

    Full Text Available The U.S. counter terrorism on ISIS had implemented with various strategies including degrading ISIS’s capability, shaping global coalition to defeat ISIS, and using trained military armed men for Iraq army forces, Kurdi army, Arabian army, and moderate opposition groups to fight against Bassar. In early 2015, U.S. government described the group as “losing this fight” and reported that anti- ISIS operations had killed more than 8,500 fighters, destroyed hundreds of vehicles and heavy weapons systems, and significantly degraded IS command and control capabilities. Unfortunately, ISIS still exists with their weapons. Moreover, the fear against ISIS and the worst conditions it brings are not exclusive in Syria, Iraq and Libya as the conflict has already spread to many countries in Europe. These countries are in dilemma because despite being affected by the conflict, still they intend to give asylum to the refugees, but their concern is that with refugees coming in, there might be exporting of ISIS’s ideologies which leads to bigger and more serious concerns than the possibility of economic instability. Inevitably, there have been questions regarding the existence of ISIS today: How can groups such as ISIS still exists despite being attacked for 3 years by the U.S? The reality is that the U.S. initiated the establishment of new and democratic governments in Afghanistan, Iraq, and Libya few years ago bothers some experts on the continuing existence of ISIS.

  19. PACKET ROUTING ALGORITHM FOR LEO SATELLITE CONSTELLATION NETWORK

    Institute of Scientific and Technical Information of China (English)

    Wang Kaidong; Tian Bin; Yi Kechu

    2005-01-01

    A novel distributed packet routing algorithm for Low Earth Orbit (LEO) satellite networks based on spiderweb topology is presented. The algorithm gives the shortest path with very low computational complexity and without on-board routing tables, which is suitable and practical for on-board processing. Simulation results show its practicability and feasibility.

  20. Network design tool for EHF satellite communications networks

    Science.gov (United States)

    Norvell, S.; Brown, G. J.

    1983-06-01

    This document describes the design concept of the network design tool. The network design tool (NDT) is a collection of analytical techniques, algorithms and simulation methods that may be used to characterize the performance of a computer communication network. Much work has been done over the past several years in network performance analysis and many techniques have been developed or proposed. Each of these methods applies to a particular aspect of the network design and is based on a particular modeling point of view. We define the computer communication network and then describe the different ways the network may be modeled. Each network model is related to the particular design problem being addressed. The various analytical approaches are briefly described and their relationship to the network models discussed. Chapter 2 is a survey of the major approaches to specific network design problems while chapters 3 and 4 discuss two fairly well defined areas of network analysis: topological design/optimization and protocol validation. Chapter 5 is a survey of network design tools presently available locally or on the advanced research projects agency network (ARPANET). Finally, chapter 6 presents an outline of the NDT specification.

  1. Future integrated broadband fiber, wireless, and satellite networks

    Science.gov (United States)

    Chan, Vincent W. S.

    2006-10-01

    With the increasing technical maturity in fiber, wireless and satellite communication technologies, new horizons are becoming feasible for future broadband networks, providing economical data rates well in excess of Gbps for stationary and mobile users as well as novel applications these advanced network services will permit. This talk explores the future architecture possibilities of such a network using new and radical technology building blocks such as: free space laser communications, multiple access multi-beam data satellite communications, novel all-optical network transport/switching and analog transmission and processing over optical carriers that support coherent distributed platform sensing and communications. We will articulate why we have to design this new network across layers from the Physical Layer to the Network and Transport Layers (even the Application Layer). Not only can future network performance and cost undergo quantum-leap improvements; such a network can have profound transforming effects on space and terrestrial system architectures for sensing, healthcare, early warning systems, disaster relief, research collaborations and other new commercial applications.

  2. ISIS网络恐怖主义活动对我国的影响及其对策研究%Research on the Influence of ISIS Network Terrorist Activities on China and China’s Countermeasures

    Institute of Scientific and Technical Information of China (English)

    况欣芷

    2016-01-01

    ISIS has posed a potential threat to China’s national security through network terrorist ac-tivities. The spreading of terrorism online is the cause of the high occurrence rate of riot and terrorist ac-tivities, and is detrimental to the social security. Against the backdrop of globalization and information age, China finds that the terrorism situation is getting increasingly severe and it is urgent to step up the construction of network counter-terrorism mechanism in China. Through the analysis of ISIS terrorist activities’ features and influence on China, we should reasonably define “cyber terrorism” and strengthen the construction of network counter-terrorism mechanism and network counter-terrorism law system so as to realize the governance of network counter-terrorism.%ISIS通过网络进行恐怖主义活动,对我国国家安全造成了潜在威胁。在全球化,信息化的时代背景下,我国的反恐形势日益严峻,必须加快网络反恐机制的构建。文章通过对ISIS相关恐怖主义活动及其特点和对我国的影响等方面的分析,得出我们需要合理界定“网络恐怖主义”这一概念,同时加强网络反恐的机制建设与网络反恐法律制度建设等,来实现对网络反恐活动的治理。

  3. ISIS Individualized Support In Sequencing

    NARCIS (Netherlands)

    Drachsler, Hendrik; Hummel, Hans

    2007-01-01

    Drachsler, H., & Hummel, H. G. K. (2007). ISIS Individualized Support In Sequencing. Presentation given during the PIP meeting on March 22, 2007. Open University of the Netherlands: Heerlen, The Netherlands.

  4. Generic ISIS Transport Module Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The purpose of the Generic ISIS Transport Module is to provide a means to bring living specimens to and from orbit. In addition to living specimens, the module can...

  5. NNIC—neural network image compressor for satellite positioning system

    Science.gov (United States)

    Danchenko, Pavel; Lifshits, Feodor; Orion, Itzhak; Koren, Sion; Solomon, Alan D.; Mark, Shlomo

    2007-04-01

    We have developed an algorithm, based on novel techniques of data compression and neural networks for the optimal positioning of a satellite. The algorithm is described in detail, and examples of its application are given. The heart of this algorithm is the program NNIC—neural network image compressor. This program was developed for compression color and grayscale images with artificial neural networks (ANNs). NNIC applies three different methods for compression. Two of them are based on neural networks architectures—multilayer perceptron and kohonen network. The third is based on a widely used method of discrete cosine transform, the basis for the JPEG standard. The program also serves as a tool for determining numerical and visual quality parameters of compression and comparison between different methods. A number of advantages and disadvantages of the compression using ANNs were discovered in the course of the present research, some of them presented in this report. The thrust of the report is the discussion of ANNs implementation problems for modern platforms, such as a satellite positioning system that include intensive image flowing and processing.

  6. Hierarchical Supervisor and Agent Routing Algorithm in LEO/MEO Double-layered Optical Satellite Network

    Science.gov (United States)

    Li, Yongjun; Zhao, Shanghong

    2016-09-01

    A novel routing algorithm (Hierarchical Supervisor and Agent Routing Algorithm, HSARA) for LEO/MEO (low earth orbit/medium earth orbit) double-layered optical satellite network is brought forward. The so-called supervisor (MEO satellite) is designed for failure recovery and network management. LEO satellites are grouped according to the virtual managed field of MEO which is different from coverage area of MEO satellite in RF satellite network. In each LEO group, one LEO satellite which has maximal persistent link with its supervisor is called the agent. A LEO group is updated when this optical inter-orbit links between agent LEO satellite and the corresponding MEO satellite supervisor cuts off. In this way, computations of topology changes and LEO group updating can be decreased. Expense of routing is integration of delay and wavelength utilization. HSARA algorithm simulations are implemented and the results are as follows: average network delay of HSARA can reduce 21 ms and 31.2 ms compared with traditional multilayered satellite routing and single-layer LEO satellite respectively; LEO/MEO double-layered optical satellite network can cover polar region which cannot be covered by single-layered LEO satellite and throughput is 1% more than that of single-layered LEO satellite averagely. Therefore, exact global coverage can be achieved with this double-layered optical satellite network.

  7. A Time and Space-based Dynamic IP Routing in Broadband Satellite Networks

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The topology architecture, characteristics and routing technologies of broadband satellite networks are studied in this paper. The authors propose the routing scheme of satellite networks and design a time and space-based distributed routing algorithm whose complexity is O(1). Simulation results aiming at satellite mobility show that the new algorithm can determine the minimum propagation delay paths effectively.

  8. Reconstructing regional climate networks from irregularly sampled satellite data

    Science.gov (United States)

    Wiedermann, Marc; Donner, Reik V.; Sykioti, Olga; Papadimitriou, Constantinos; Kurths, Jürgen

    2015-04-01

    With the increasing availability of remote sensing data Earth System Analysis has taken a great step forward. Satellite data with high resolution in time and space allow for an in-depth analysis of small-scale processes in the climate as well as ecosystems. This data type, however, also harbors crucial conceptual complications. First, depending on whether the satellite is orbiting on an ascending or descending path systematic biases are induced into the dataset and both measurements can not be evaluated simultaneously without an appropriate preprocessing. Second, remote sensing data are usually not produced with equidistant temporal sampling, but might contain huge gaps, due to cloud cover or maintenance work and irregular time steps, due to the orbiting time of the satellite. In this work, we utilize sea surface temperature (SST) data obtained from the SMOS satellite as part of ESA's Earth Explorer Mission to study small-scale regional interactions between different parts of the Mediterranean, Aegean and Black Sea. In a first step, we create homogeneous time series for each grid point by combining data from ascending and descending satellite paths by utilizing principal component and singular spectrum analysis. To address the issue of irregular temporal sampling we utilize a kernel weighted version of the linear cross-correlation function to compute lagged correlations between all pairs of grid points in the dataset. By setting a threshold to the thus obtained correlation matrix we obtain a binary matrix which can be interpreted as the adjacency matrix of a complex network. We then use tools from complex network theory to study regional interdependencies in the study area for different time lags of up to forty days. We find that the obtained networks represent well the observed average wind directions and speeds and display interaction structures between small regions in the Aegean Sea, which are in good agreement with earlier observations. The methods presented

  9. Satellite -Based Networks for U-Health & U-Learning

    Science.gov (United States)

    Graschew, G.; Roelofs, T. A.; Rakowsky, S.; Schlag, P. M.

    2008-08-01

    The use of modern Information and Communication Technologies (ICT) as enabling tools for healthcare services (eHealth) introduces new ways of creating ubiquitous access to high-level medical care for all, anytime and anywhere (uHealth). Satellite communication constitutes one of the most flexible methods of broadband communication offering high reliability and cost-effectiveness of connections meeting telemedicine communication requirements. Global networks and the use of computers for educational purposes stimulate and support the development of virtual universities for e-learning. Especially real-time interactive applications can play an important role in tailored and personalised services.

  10. New dynamic routing algorithm based on MANET in LEO/MEO satellite network

    Institute of Scientific and Technical Information of China (English)

    LI Zhe; LI Dong-ni; WANG Guang-xing

    2006-01-01

    The features of low earth orbit/medium earth orbit (LEO/MEO) satellite networks routing algorithm based on inter-satellite link are analyzed and the similarities between satellite networks and mobile Ad Hoc network (MANET) are pointed out.The similar parts in MANET routing protocol are used in the satellite network for reference.A new dynamic routing algorithm based on MANET in LEO/MEO satellite networks,which fits for the LEO/MEO satellite communication system,is proposed.At the same time,the model of the algorithm is simulated and features are analyzed.It is shown that the algorithm has strong adaptability.It can give the network high autonomy,perfect function,low system overhead and great compatibility.

  11. Hardware demonstration of high-speed networks for satellite applications.

    Energy Technology Data Exchange (ETDEWEB)

    Donaldson, Jonathon W.; Lee, David S.

    2008-09-01

    This report documents the implementation results of a hardware demonstration utilizing the Serial RapidIO{trademark} and SpaceWire protocols that was funded by Sandia National Laboratories (SNL's) Laboratory Directed Research and Development (LDRD) office. This demonstration was one of the activities in the Modeling and Design of High-Speed Networks for Satellite Applications LDRD. This effort has demonstrated the transport of application layer packets across both RapidIO and SpaceWire networks to a common downlink destination using small topologies comprised of commercial-off-the-shelf and custom devices. The RapidFET and NEX-SRIO debug and verification tools were instrumental in the successful implementation of the RapidIO hardware demonstration. The SpaceWire hardware demonstration successfully demonstrated the transfer and routing of application data packets between multiple nodes and also was able reprogram remote nodes using configuration bitfiles transmitted over the network, a key feature proposed in node-based architectures (NBAs). Although a much larger network (at least 18 to 27 nodes) would be required to fully verify the design for use in a real-world application, this demonstration has shown that both RapidIO and SpaceWire are capable of routing application packets across a network to a common downlink node, illustrating their potential use in real-world NBAs.

  12. Domitian between Isis and Minerva

    DEFF Research Database (Denmark)

    Clausen, Kristine Bülow

    2013-01-01

    group of Graeco-Roman sculptures, the paper also examines the association of Isis and Minerva and, ultimately, Magna Mater. The paper finally discusses the important role of this divine trinity, as well as the role of the Beneventan Iseum in relation to the official ideology of the Flavian emperors....

  13. Evaluatie van ISIS-MML

    NARCIS (Netherlands)

    Benthem BHB van; EPI

    2007-01-01

    The Infectious Diseases Surveillance Information system that collects data of medical microbiology laboratories in the Netherlands (ISIS-MML) is not suitable for early warning of infectious diseases outbreaks. However, the system is appropriate for monitoring trends in antimicrobial resistance. The

  14. Convolutional neural network features based change detection in satellite images

    Science.gov (United States)

    Mohammed El Amin, Arabi; Liu, Qingjie; Wang, Yunhong

    2016-07-01

    With the popular use of high resolution remote sensing (HRRS) satellite images, a huge research efforts have been placed on change detection (CD) problem. An effective feature selection method can significantly boost the final result. While hand-designed features have proven difficulties to design features that effectively capture high and mid-level representations, the recent developments in machine learning (Deep Learning) omit this problem by learning hierarchical representation in an unsupervised manner directly from data without human intervention. In this letter, we propose approaching the change detection problem from a feature learning perspective. A novel deep Convolutional Neural Networks (CNN) features based HR satellite images change detection method is proposed. The main guideline is to produce a change detection map directly from two images using a pretrained CNN. This method can omit the limited performance of hand-crafted features. Firstly, CNN features are extracted through different convolutional layers. Then, a concatenation step is evaluated after an normalization step, resulting in a unique higher dimensional feature map. Finally, a change map was computed using pixel-wise Euclidean distance. Our method has been validated on real bitemporal HRRS satellite images according to qualitative and quantitative analyses. The results obtained confirm the interest of the proposed method.

  15. A study of multiple access schemes in satellite control network

    Science.gov (United States)

    Mo, Zijian; Wang, Zhonghai; Xiang, Xingyu; Wang, Gang; Chen, Genshe; Nguyen, Tien; Pham, Khanh; Blasch, Erik

    2016-05-01

    Satellite Control Networks (SCN) have provided launch control for space lift vehicles; tracking, telemetry and commanding (TTC) for on-orbit satellites; and, test support for space experiments since the 1960s. Currently, SCNs encounter a new challenge: how to maintain the high reliability of services when sharing the spectrum with emerging commercial services. To achieve this goal, the capability of multiple satellites reception is deserved as an update/modernization of SCN in the future. In this paper, we conducts an investigation of multiple access techniques in SCN scenario, e.g., frequency division multiple access (FDMA) and coded division multiple access (CDMA). First, we introduce two upgrade options of SCN based on FDMA and CDMA techniques. Correspondingly, we also provide their performance analysis, especially the system improvement in spectrum efficiency and interference mitigation. Finally, to determine the optimum upgrade option, this work uses CRISP, i.e., Cost, Risk, Installation, Supportability and Performance, as the baseline approach for a comprehensive trade study of these two options. Extensive numerical and simulation results are presented to illustrate the theoretical development.

  16. Regional climate network analysis from irregularly sampled satellite data

    Science.gov (United States)

    Wiedermann, Marc; Sykioti, Olga; Papadimitriou, Constantinos; Balasis, George; Kurths, Jürgen; Donner, Reik V.

    2016-04-01

    With the increasing availability of remote sensing data Earth System Analysis has taken a great step forward. This type of data, however, also harbors a variety of conceptual complications. First, depending on whether the satellite is orbiting on an ascending or descending path systematic biases are induced into the data, and both measurements cannot be evaluated simultaneously without an appropriate preprocessing. Second, remote sensing data are usually not produced with equidistant temporal sampling, but might contain huge gaps and irregular time steps. Third, the time period covered by the data is often too short to perform an appropriate seasonal detrending. Here, we propose a general framework to create homogeneous anomalized time series for a (multivariate) satellite data set by combining time series from ascending and descending satellite paths or even different missions using principal component and singular spectrum analysis. We then exemplarily apply our method to sea surface temperature data obtained from the SMOS satellite mission to study small-scale regional correlative patterns covering different parts of the Aegean Sea. To address the issue of irregular temporal sampling we utilize a kernel weighted version of the linear cross-correlation function to compute lagged correlations between all pairs of grid points in the data set. By binarizing the thus obtained matrices, we obtain a network representation of the system's similarity structure. Ultimately, we use tools from complex network theory to study regional interdependencies in the study area for different time lags of up to forty days. We find that the obtained networks represent well the observed average wind directions and speeds and display interaction structures between small regions in the Aegean Sea, which are in good agreement with earlier observations. In a second step, we extend the study area to the whole Mediterranean and Black Sea and investigate lagged interactions between these two

  17. A Multicast Routing Algorithm for Datagram Service in Delta LEO Satellite Constellation Networks

    Directory of Open Access Journals (Sweden)

    Yanpeng Ma

    2014-04-01

    Full Text Available Satellites can broadcast datagram over wide areas, therefore, the satellite network has congenital advantages to implement multicast service. LEO satellite has the property of efficient bandwidth usage, lower propagation delay and lower power consumption in the user terminals and satellites. Therefore, the constellation network composed by LEO satellites is an essential part of future satellite communication networks. In this paper, we propose a virtual center based multicast (VCMulticast routing algorithm for LEO satellite constellation network. The algorithm uses the geographic center information of group users to route multicast datagrams, with less memory, computer power and signaling overhead. We evaluate the delay and performance of our algorithm by means of simulations in the OPENET simulator. The results indicate that the delay of the proposed multicast method exceeds the minimum propagation by at most 29.1% on the average, which is a quite acceptable achievement, considering the resource overhead reduction that can be introduced by our proposal

  18. Prof. Zhu Zuoyan Met with ISI Delegation

    Institute of Scientific and Technical Information of China (English)

    Liu Xiuping; Chen Huai

    2007-01-01

    @@ On March 27, Prof. Zhu Zuoyan, Vice President of NSFC, met with a three-member delegation from the Institute for Scientific Information (ISI), USA headed by Dr. James Testa, Director of Editorial Development of ISI.

  19. Applications of a Networked Array of Small Satellites for Planetary Observation

    NARCIS (Netherlands)

    Gunter, B.C.; Maessen, D.C.

    2010-01-01

    The goal of this study is to explore those applications which can best utilize a network of orbiting satellites working as a distributed computing array. The satellites are presumed to be low-cost mini- or micro-satellites orbiting Earth or some other celestial body (i.e., an asteroid, moon, etc.),

  20. Applications of a Networked Array of Small Satellites for Planetary Observation

    NARCIS (Netherlands)

    Gunter, B.C.; Maessen, D.C.

    2010-01-01

    The goal of this study is to explore those applications which can best utilize a network of orbiting satellites working as a distributed computing array. The satellites are presumed to be low-cost mini- or micro-satellites orbiting Earth or some other celestial body (i.e., an asteroid, moon, etc.),

  1. KARMEN: neutrino spectroscopy at ISIS

    Energy Technology Data Exchange (ETDEWEB)

    Drexlin, G. [Forschungszentrum Karlsruhe GmbH Technik und Umwelt (Germany). Inst. fuer Kernphysik

    1996-11-01

    The Karlsruhe-Rutherford Neutrino Experiment KARMEN at the spallation neutron facility ISIS investigates fundamental properties of neutrinos as well as their interactions with matter. Low energy neutrinos with energies up to 50 MeV emitted by the pulsed {nu}-source ISIS are detected by a 56 tonne high resolution liquid scintillation calorimeter. Clear {nu}-signatures allow a reliable search for neutrino oscillations of the type {nu}{sub {mu}}{yields}{nu}{sub e} and {nu}{sub {mu}}{yields}{nu}{sub e} as well as a detailed investigation of neutrino-nucleus interactions in an energy range important for astrophysics. We present the results of the KARMEN experiment from data taking in the period from June 1990 - December 1995. (author) 9 figs., 10 refs.

  2. Comparison of Data Quality of NOAA's ISIS and SURFRAD Networks to NREL's SRRL-BMS

    Energy Technology Data Exchange (ETDEWEB)

    Anderberg, M.; Sengupta, M.

    2014-11-01

    This report provides analyses of broadband solar radiometric data quality for the National Oceanic and Atmospheric Administration's Integrated Surface Irradiance Study and Surface Radiation Budget Network (SURFRAD) solar measurement networks. The data quality of these networks is compared to that of the National Renewable Energy Laboratory's Solar Radiation Research Laboratory Baseline Measurement System (SRRL-BMS) native data resolutions and hourly averages of the data from the years 2002 through 2013. This report describes the solar radiometric data quality testing and flagging procedures and the method used to determine and tabulate data quality statistics. Monthly data quality statistics for each network were plotted by year against the statistics for the SRRL-BMS. Some of the plots are presented in the body of the report, but most are in the appendix. These plots indicate that the overall solar radiometric data quality of the SURFRAD network is superior to that of the Integrated Surface Irradiance Study network and can be comparable to SRRL-BMS.

  3. TCP-ATCA: Improved Transmission Control Algorithm in Satellite Network

    Institute of Scientific and Technical Information of China (English)

    Liu Feng; Liu Hengna; Zhao Han

    2008-01-01

    An adaptive transmission control algorithm based on TCP (TCP-ATCA) is proposed to reduce the effects of long propagation de- lay and high link error rate of the satellite network on the performances. The flow control and the error recovery are differentiated by combined dynamic random early detection-explicit congestion notification (DRED-ECN) algorithm, and, moreover, the pertaining con- gestion control methods are used in TCP-ATCA to improve the throughput. By introducing the entire recovery algorithm, the unneces- sary congestion window decrease is reduced, and the throughput and fairness are improved. Simulation results show that, compared with TCP-Reno, TCP-ATCA provides a better throughput performance when the link capacity is higher (≥ 600 packet/s), and roughly the same when it is lower. At the same time, TCP-ATCA also increases fairness and reduces transmission delay.

  4. Economically sustainable public security and emergency network exploiting a broadband communications satellite

    OpenAIRE

    Lawal, Lasisi Salami

    2014-01-01

    The research contributes to work in Rapid Deployment of a National Public Security and Emergency Communications Network using Communication Satellite Broadband. Although studies in Public Security Communication networks have examined the use of communications satellite as an integral part of the Communication Infrastructure, there has not been an in-depth design analysis of an optimized regional broadband-based communication satellite in relation to the envisaged service coverage area, with l...

  5. Capacity Model and Constraints Analysis for Integrated Remote Wireless Sensor and Satellite Network in Emergency Scenarios

    Directory of Open Access Journals (Sweden)

    Wei Zhang

    2015-11-01

    Full Text Available This article investigates the capacity problem of an integrated remote wireless sensor and satellite network (IWSSN in emergency scenarios. We formulate a general model to evaluate the remote sensor and satellite network capacity. Compared to most existing works for ground networks, the proposed model is time varying and space oriented. To capture the characteristics of a practical network, we sift through major capacity-impacting constraints and analyze the influence of these constraints. Specifically, we combine the geometric satellite orbit model and satellite tool kit (STK engineering software to quantify the trends of the capacity constraints. Our objective in analyzing these trends is to provide insights and design guidelines for optimizing the integrated remote wireless sensor and satellite network schedules. Simulation results validate the theoretical analysis of capacity trends and show the optimization opportunities of the IWSSN.

  6. Enhancing End-to-End Performance of Information Services Over Ka-Band Global Satellite Networks

    Science.gov (United States)

    Bhasin, Kul B.; Glover, Daniel R.; Ivancic, William D.; vonDeak, Thomas C.

    1997-01-01

    The Internet has been growing at a rapid rate as the key medium to provide information services such as e-mail, WWW and multimedia etc., however its global reach is limited. Ka-band communication satellite networks are being developed to increase the accessibility of information services via the Internet at global scale. There is need to assess satellite networks in their ability to provide these services and interconnect seamlessly with existing and proposed terrestrial telecommunication networks. In this paper the significant issues and requirements in providing end-to-end high performance for the delivery of information services over satellite networks based on various layers in the OSI reference model are identified. Key experiments have been performed to evaluate the performance of digital video and Internet over satellite-like testbeds. The results of the early developments in ATM and TCP protocols over satellite networks are summarized.

  7. Energy-Efficient Optimal Power Allocation in Integrated Wireless Sensor and Cognitive Satellite Terrestrial Networks.

    Science.gov (United States)

    Shi, Shengchao; Li, Guangxia; An, Kang; Gao, Bin; Zheng, Gan

    2017-09-04

    This paper proposes novel satellite-based wireless sensor networks (WSNs), which integrate the WSN with the cognitive satellite terrestrial network. Having the ability to provide seamless network access and alleviate the spectrum scarcity, cognitive satellite terrestrial networks are considered as a promising candidate for future wireless networks with emerging requirements of ubiquitous broadband applications and increasing demand for spectral resources. With the emerging environmental and energy cost concerns in communication systems, explicit concerns on energy efficient resource allocation in satellite networks have also recently received considerable attention. In this regard, this paper proposes energy-efficient optimal power allocation schemes in the cognitive satellite terrestrial networks for non-real-time and real-time applications, respectively, which maximize the energy efficiency (EE) of the cognitive satellite user while guaranteeing the interference at the primary terrestrial user below an acceptable level. Specifically, average interference power (AIP) constraint is employed to protect the communication quality of the primary terrestrial user while average transmit power (ATP) or peak transmit power (PTP) constraint is adopted to regulate the transmit power of the satellite user. Since the energy-efficient power allocation optimization problem belongs to the nonlinear concave fractional programming problem, we solve it by combining Dinkelbach's method with Lagrange duality method. Simulation results demonstrate that the fading severity of the terrestrial interference link is favorable to the satellite user who can achieve EE gain under the ATP constraint comparing to the PTP constraint.

  8. Neural Network Based Lna Design for Mobile Satellite Receiver

    Directory of Open Access Journals (Sweden)

    Abhijeet Upadhya

    2014-08-01

    Full Text Available Paper presents a Neural Network Modelling approach to microwave LNA design. To acknowledge the specifications of the amplifier, Mobile Satellite Systems are analyzed. Scattering parameters of the LNA in the frequency range 0.5 to 18 GHz are calculated using a Multilayer Perceptron Artificial Neural Network model and corresponding smith charts and polar charts are plotted as output to the model. From these plots, the microwave scattering parameter description of the LNA are obtained. Model is efficiently trained using Agilent ATF 331M4 InGaAs/InP Low Noise pHEMT amplifier datasheet and the neural model’s output seem to follow the various device characteristic curves with high regression. Next, Maximum Allowable Gain and Noise figure of the device are modelled and plotted for the same frequency range. Finally, the optimized model is utilized as an interpolator and the resolution of the amplifying capability with noise characteristics are obtained for the L Band of MSS operation.

  9. Light-Ion-Induced Multifragmentation: The ISiS Project

    CERN Document Server

    Viola, V E

    2006-01-01

    An extensive study of GeV light-ion-induced multifragmentation and its possible interpretation in terms of a nuclear liquid-gas phase transition has been performed with the Indiana Silicon Sphere (ISiS)4 pi detector array. Measurements were performed with 5-15 GeV/c p, pbar, and pion beams incident on $^{197}$Au and 2-5 GeV $^3$He incident on $^{nat}$Ag and $^{197}$Au targets. Both the reaction dynamics and the subsequent decay of the heavy residues have been explored. The data provide evidence for a dramatic change in the reaction observables near an excitation energy of E*/A = 4-5 MeV per residue nucleon. In this region, fragment multiplicities and energy spectra indicate emission from an expanded/dilute source on a very short time scale (20-50 fm/c). These properties, along with caloric curve and scaling-law behavior, yield a pattern that is consistent with a nuclear liquid-gas phase transition.

  10. Light-ion-induced multifragmentation: The ISiS project

    Science.gov (United States)

    Viola, V. E.; Kwiatkowski, K.; Beaulieu, L.; Bracken, D. S.; Breuer, H.; Brzychczyk, J.; de Souza, R. T.; Ginger, D. S.; Hsi, W.-C.; Korteling, R. G.; Lefort, T.; Lynch, W. G.; Morley, K. B.; Legrain, R.; Pienkowski, L.; Pollacco, E. C.; Renshaw, E.; Ruangma, A.; Tsang, M. B.; Volant, C.; Wang, G.; Yennello, S. J.; Yoder, N. R.

    2006-11-01

    An extensive study of GeV light-ion-induced multifragmentation and its possible interpretation in terms of a nuclear liquid-gas phase transition has been performed with the Indiana Silicon Sphere (ISiS) 4π detector array. Measurements were performed with 5-15 GeV/ c p, pbar, and π- beams incident on 197Au and 2-5 GeV 3He incident on natAg and 197Au targets. Both the reaction dynamics and the subsequent decay of the heavy residues have been explored. The data provide evidence for a dramatic change in the reaction observables near an excitation energy of E*/A=4-5 MeV/residue nucleon. In this region, fragment multiplicities and energy spectra indicate emission from an expanded/dilute source on a very short time scale (20-50 fm/ c). These properties, along with caloric curve and scaling-law behavior, yield a pattern that is consistent with a nuclear liquid-gas phase transition.

  11. Network Performance Evaluation of Abis Interface over DVB-S2 in the GSM over Satellite Network

    Directory of Open Access Journals (Sweden)

    S. B. Musabekov

    2010-01-01

    Full Text Available This paper deals with establishing a GSM link over Satellite. Abis interface, which is defined between Base Transceiver Station (BTS and Base Station Controller (BSC, in a GSM network is considered here to be routed over the Satellite. The satellite link enables a quick and cost-effective GSM link in meagerly populated areas. A different scenario comparison was done to understand the impact of Satellite environment on network availability comparing to terrestrial scenario. We have implemented an Abis interface over DVB S2 in NS2 and evaluated the performance over the high delay and loss satellite channel. Network performance was evaluated with respect to Satellite channel delay and DVB S2 encapsulation efficiency under different amount of user traffic and compared with the terrestrial scenario. The results clearly showed an increased amount of SDCCH and TCH channels required in the case of satellite scenario for the same amount of traffic in comparison to conventional terrestrial scenario. We have optimized the parameters based on the simulation results. Link budget estimation considering DVB-S2 platform was done to find satellite bandwidth and cost requirements for different network setups.

  12. Study on networking issues of medium earth orbit satellite communications systems

    Science.gov (United States)

    Araki, Noriyuki; Shinonaga, Hideyuki; Ito, Yasuhiko

    1993-01-01

    Two networking issues of communications systems with medium earth orbit (MEO) satellites, namely network architectures and location determination and registration methods for hand-held terminals, are investigated in this paper. For network architecture, five candidate architectures are considered and evaluated in terms of signaling traffic. For location determination and registration, two methods are discussed and evaluated.

  13. Beam forming networks for mm-wave satellite communications

    Science.gov (United States)

    Sharon, T. E.

    1983-01-01

    Technology features of a beam forming network (BFN) employing ferrite devices to provide multiple beam antenna pattern control for satellites used in telecommunications are described. The BFN produces the phase and amplitude distribution for each horn in an antenna array, with the number of horns in the array being equal to the number of outputs in the BFN. One configuration involves microwave switches and permits illumination of a single feed horn at a time using ferrite latching circulators that function by reversing the circulation direction. A more flexible version, yielding a variable amplitude distribution across the feed horn array to accommodate changing traffic patterns or serving a TDMA system, includes the capability of forming nulls in the system with a variable phase shifter in the input ports. The antenna scan angles in phased arrays can be limited to 8 deg from center. Acceptable insertion losses have been demonstrated in BFN with hundreds of ports and switching rates as high as 10 kHz.

  14. Beam forming networks for mm-wave satellite communications

    Science.gov (United States)

    Sharon, T. E.

    1983-08-01

    Technology features of a beam forming network (BFN) employing ferrite devices to provide multiple beam antenna pattern control for satellites used in telecommunications are described. The BFN produces the phase and amplitude distribution for each horn in an antenna array, with the number of horns in the array being equal to the number of outputs in the BFN. One configuration involves microwave switches and permits illumination of a single feed horn at a time using ferrite latching circulators that function by reversing the circulation direction. A more flexible version, yielding a variable amplitude distribution across the feed horn array to accommodate changing traffic patterns or serving a TDMA system, includes the capability of forming nulls in the system with a variable phase shifter in the input ports. The antenna scan angles in phased arrays can be limited to 8 deg from center. Acceptable insertion losses have been demonstrated in BFN with hundreds of ports and switching rates as high as 10 kHz.

  15. Network design for telemedicine--e-health using satellite technology.

    Science.gov (United States)

    Graschew, Georgi; Roelofs, Theo A; Rakowsky, Stefan; Schlag, Peter M

    2008-01-01

    Over the last decade various international Information and Communications Technology networks have been created for a global access to high-level medical care. OP 2000 has designed and validated the high-end interactive video communication system WinVicos especially for telemedical applications, training of the physician in a distributed environment, teleconsultation and second opinion. WinVicos is operated on a workstation (WoTeSa) using standard hardware components and offers a superior image quality at a moderate transmission bandwidth of up to 2 Mbps. WoTeSa / WinVicos have been applied for IP-based communication in different satellite-based telemedical networks. In the DELTASS-project a disaster scenario was analysed and an appropriate telecommunication system for effective rescue measures for the victims was set up and evaluated. In the MEDASHIP project an integrated system for telemedical services (teleconsultation, teleelectro-cardiography, telesonography) on board of cruise ships and ferries has been set up. EMISPHER offers an equal access for most of the countries of the Euro-Mediterranean area to on-line services for health care in the required quality of service. E-learning applications, real-time telemedicine and shared management of medical assistance have been realized. The innovative developments in ICT with the aim of realizing a ubiquitous access to medical resources for everyone at any time and anywhere (u-Health) bear the risk of creating and amplifying a digital divide in the world. Therefore we have analyzed how the objective needs of the heterogeneous partners can be joined with the result that there is a need for real integration of the various platforms and services. A virtual combination of applications serves as the basic idea for the Virtual Hospital. The development of virtual hospitals and digital medicine helps to bridge the digital divide between different regions of the world and enables equal access to high-level medical care. Pre

  16. A Novel Onboard-gateway-based Mechanism to Improve TCP Performance in Aeronautical Satellite Networks

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The IP-based networks on aircraft serve to support Internet services via satellites. However, in aeronautical satellite hybrid networks, the TCP protocol performance often deteriorates due to improper decreases and slow recovery of the congestion window. This paper proposes a window size determination and notification mechanism, onboard-gateway-based mechanism (OGBM), which is based on the onboard gateway in the networks on aircraft. A cross-layer approach is adopted by the onboard gateway to obtain the satellite link bandwidth information. And then, by the gateway, through changing the receiver's advertised window field in ACK packets, TCP sources are notified of the window size of each TCP source calculated on the ground of bandwidth delay product and flow numbers. The mechanism is able to avoid improper changes of TCP window and serve multiple users. Simulation results show that the mechanism with the fairness index close to 1 improves TCP performance in aeronautical satellite networks.

  17. Potentials and Limitations of CDMA Networks for Combined Inter-Satellite Communication and Relative Navigation

    NARCIS (Netherlands)

    Sun, R.; Guo, J.; Gill, E.K.A.; Maessen, D.C.

    2012-01-01

    Precision formation flying missions require formation acquisition and maintenance through the interactions among spacecraft by the inter-satellite communication and relative navigation. This paper analyses the dedicated system constraints of the network architecture for precision formation flying mi

  18. Innovative Large Scale Wireless Sensor Network Architecture Using Satellites and High-Altitude Platforms

    Directory of Open Access Journals (Sweden)

    Yasser Albagory

    2014-03-01

    Full Text Available Wireless sensor network has many applications and very active research area. The coverage span of this network is very important parameter where wide coverage area is a challenge. This paper proposes an architecture for large-scale wireless sensor network (LSWSN based on satellites and the High-Altitude Platforms (HAP where the sensor nodes are located on the ground and a wide coverage sink station may be in the form of a satellite or a network of HAPs. A scenario is described for multilayer LSWSN and a study for the system requirements has been established showing the number of Satellites, HAPs and coverage per each sink according to the elevation angle requirements. The Satellite-HAP-Sensor multilayer LSWSN architecture has the feasibility for effective energy and earth coverage and is optimum for covering largely sparse regions.

  19. Cooperative network clustering and task allocation for heterogeneous small satellite network

    Science.gov (United States)

    Qin, Jing

    The research of small satellite has emerged as a hot topic in recent years because of its economical prospects and convenience in launching and design. Due to the size and energy constraints of small satellites, forming a small satellite network(SSN) in which all the satellites cooperate with each other to finish tasks is an efficient and effective way to utilize them. In this dissertation, I designed and evaluated a weight based dominating set clustering algorithm, which efficiently organizes the satellites into stable clusters. The traditional clustering algorithms of large monolithic satellite networks, such as formation flying and satellite swarm, are often limited on automatic formation of clusters. Therefore, a novel Distributed Weight based Dominating Set(DWDS) clustering algorithm is designed to address the clustering problems in the stochastically deployed SSNs. Considering the unique features of small satellites, this algorithm is able to form the clusters efficiently and stably. In this algorithm, satellites are separated into different groups according to their spatial characteristics. A minimum dominating set is chosen as the candidate cluster head set based on their weights, which is a weighted combination of residual energy and connection degree. Then the cluster heads admit new neighbors that accept their invitations into the cluster, until the maximum cluster size is reached. Evaluated by the simulation results, in a SSN with 200 to 800 nodes, the algorithm is able to efficiently cluster more than 90% of nodes in 3 seconds. The Deadline Based Resource Balancing (DBRB) task allocation algorithm is designed for efficient task allocations in heterogeneous LEO small satellite networks. In the task allocation process, the dispatcher needs to consider the deadlines of the tasks as well as the residue energy of different resources for best energy utilization. We assume the tasks adopt a Map-Reduce framework, in which a task can consist of multiple

  20. Satellites vs. fiber optics based networks and services - Road map to strategic planning

    Science.gov (United States)

    Marandi, James H. R.

    An overview of a generic telecommunications network and its components is presented, and the current developments in satellite and fiber optics technologies are discussed with an eye on the trends in industry. A baseline model is proposed, and a cost comparison of fiber- vs satellite-based networks is made. A step-by-step 'road map' to the successful strategic planning of telecommunications services and facilities is presented. This road map provides for optimization of the current and future networks and services through effective utilization of both satellites and fiber optics. The road map is then applied to different segments of the telecommunications industry and market place, to show its effectiveness for the strategic planning of executives of three types: (1) those heading telecommunications manufacturing concerns, (2) those leading communication service companies, and (3) managers of telecommunication/MIS departments of major corporations. Future networking issues, such as developments in integrated-services digital network standards and technologies, are addressed.

  1. Performance tests of a satellite-based asymmetric communication network for the 'hyper hospital'.

    Science.gov (United States)

    Yamaguchi, T

    1997-01-01

    The Hyper Hospital is a prototype networked telemedicine system which uses virtual reality. We measured the performance of a novel multimedia network based on satellite communications. The network was a hybrid system consisting of a satellite channel in one direction and a terrestrial channel in the other. Each user was equipped with a standard satellite communication receiver and a telephone connection. Requests from the users were sent by modern and telephone line and responses were received by satellite. The user requests were initiated by clicking buttons on a World Wide Web browser screen. The transmission rates of satellite and normal telephone-line communications were compared for standardized text data. Satellite communication was three to five times faster. The transmission rate was also measured for standardized graphical data (GIF format). With a file size of about 400 kByte, satellite-mediated communication was 10 times faster than telephone lines. The effect of simultaneous access on performance was also explored. For simultaneous access of nine users to a single graphics file, 78% of the transmission speed was obtained in comparison with that of a single user. The satellite-based system showed excellent high-speed communication performance, particularly for multimedia data.

  2. Adaptive Distributed Load Balancing Routing Mechanism for LEO Satellite IP Networks

    Directory of Open Access Journals (Sweden)

    Xiao Ma

    2014-04-01

    Full Text Available LEO (Low Earth Orbit satellite constellation is an ideal scheme for the next generation wideband internet. The constellation is formed as a mesh-like network with inter satellite links (ISLs which are equipped between the neighbor satellites for transmitting directly. As to the future wideband IP services, an efficient routing mechanism will play an important role in improving the performance and balancing the network traffic. An Adaptive Distributed Load Balancing Routing Mechanism (ADLB is proposed in this paper to address the above-mentioned issues. This mechanism makes well-performed routing decision based on the current and historical status of each ISLs in each satellite node. With collecting historical information from network initiated, a proper mechanism is contained in ADLB for making required computing power and storage space in a reasonable range. The performance of ADLB is verified via a series of simulations which demonstrate that the scheme can provide better throughput and lower packet drop rate.

  3. Achieving QoS for TCP Traffic in Satellite Networks with Differentiated Services

    Science.gov (United States)

    Durresi, Arjan; Kota, Sastri; Goyal, Mukul; Jain, Raj; Bharani, Venkata

    2001-01-01

    Satellite networks play an indispensable role in providing global Internet access and electronic connectivity. To achieve such a global communications, provisioning of quality of service (QoS) within the advanced satellite systems is the main requirement. One of the key mechanisms of implementing the quality of service is traffic management. Traffic management becomes a crucial factor in the case of satellite network because of the limited availability of their resources. Currently, Internet Protocol (IP) only has minimal traffic management capabilities and provides best effort services. In this paper, we presented a broadband satellite network QoS model and simulated performance results. In particular, we discussed the TCP flow aggregates performance for their good behavior in the presence of competing UDP flow aggregates in the same assured forwarding. We identified several factors that affect the performance in the mixed environments and quantified their effects using a full factorial design of experiment methodology.

  4. Evolution of the NOAA National Weather Service Satellite Broadcast Network (SBN) to Europe's DVB-S satellite communications technology standard

    Science.gov (United States)

    Cragg, Phil; Brockman, William E.

    2006-08-01

    The National Oceanic and Atmospheric Administration's (NOAA) National Weather Service (NWS) uses a commercial Satellite Broadcast Network (SBN) to distribute weather data to the NWS AWIPS workstations and National Centers and to NWS Family of Service Users. Advances in science and technology from NOAA's observing systems, such as remote sensing satellites and NEXRAD radars, and advances in Numeric Weather Prediction have greatly increased the volume of data to be transmitted via the SBN. The NOAA-NWS SBN Evolution Program did a trade study resulting in the selection of Europe's DVB-S communication protocol as the basis for enabling a significant increase in the SBN capacity. The Digital Video Broadcast (DVB) group, started to develop digital TV for Europe through satellite broadcasting, has become the current standard for defining technology for satellite broadcasting of digital data for much of the world. NOAA-NWS implemented the DVB-S with inexpensive, Commercial Off The Shelf receiving equipment. The modernized NOAA-NWS SBN meets current performance goals and provides the basis for continued future expansion with no increase in current communication costs. This paper discusses aspects of the NOAA-NWS decision and the migration to the DVB-S standard for its commercial satellite broadcasts of observations and Numerical Weather Prediction data.

  5. Statistical investigations into isiZulu intonation

    CSIR Research Space (South Africa)

    Kuun, C

    2005-11-01

    Full Text Available We study the relationship between lexical tone and measured values of fundamental frequency for several word classes in isiZulu, based on objective measurements from recordings of three speakers. For nouns and adjectives, both in isolation...

  6. UMR: A utility-maximizing routing algorithm for delay-sensitive service in LEO satellite networks

    Directory of Open Access Journals (Sweden)

    Lu Yong

    2015-04-01

    Full Text Available This paper develops a routing algorithm for delay-sensitive packet transmission in a low earth orbit multi-hop satellite network consists of micro-satellites. The micro-satellite low earth orbit (MS-LEO network endures unstable link connection and frequent link congestion due to the uneven user distribution and the link capacity variations. The proposed routing algorithm, referred to as the utility maximizing routing (UMR algorithm, improve the network utility of the MS-LEO network for carrying flows with strict end-to-end delay bound requirement. In UMR, first, a link state parameter is defined to capture the link reliability on continuing to keep the end-to-end delay into constraint; then, on the basis of this parameter, a routing metric is formulated and a routing scheme is designed for balancing the reliability in delay bound guarantee among paths and building a path maximizing the network utility expectation. While the UMR algorithm has many advantages, it may result in a higher blocking rate of new calls. This phenomenon is discussed and a weight factor is introduced into UMR to provide a flexible performance option for network operator. A set of simulations are conducted to verify the good performance of UMR, in terms of balancing the traffic distribution on inter-satellite links, reducing the flow interruption rate, and improving the network utility.

  7. Design Issues for Traffic Management for the ATM UBR + Service for TCP Over Satellite Networks

    Science.gov (United States)

    Jain, Raj

    1999-01-01

    This project was a comprehensive research program for developing techniques for improving the performance of Internet protocols over Asynchronous Transfer Mode (ATM) based satellite networks. Among the service categories provided by ATM networks, the most commonly used category for data traffic is the unspecified bit rate (UBR) service. UBR allows sources to send data into the network without any feedback control. The project resulted in the numerous ATM Forum contributions and papers.

  8. A Model for the Handover Traffic and Channel Occupancy Time in LEO Satellite Networks

    Institute of Scientific and Technical Information of China (English)

    WangJingyu; YaoYongyang

    1995-01-01

    This paper presents a method to determine the parameters of the traffic model for the LEO satellite networks-the handover traffic and the mean channel occupancy time.The main idea is that the handover traffic is mainly due to the movement of the satellites and the velocity of the mobile terminals and earth rotation is ignored.The performance level can be calculated accord-ing to different handover queuing model.

  9. A Neural Network MLSE Receiver Based on Natural Gradient Descent: Application to Satellite Communications

    Directory of Open Access Journals (Sweden)

    Ibnkahla Mohamed

    2004-01-01

    Full Text Available The paper proposes a maximum likelihood sequence estimator (MLSE receiver for satellite communications. The satellite channel model is composed of a nonlinear traveling wave tube (TWT amplifier followed by a multipath propagation channel. The receiver is composed of a neural network channel estimator (NNCE and a Viterbi detector. The natural gradient (NG descent is used for training. Computer simulations show that the performance of our receiver is close to the ideal MLSE receiver in which the channel is perfectly known.

  10. Combined Geometric and Neural Network Approach to Generic Fault Diagnosis in Satellite Actuators and Sensors

    OpenAIRE

    Baldi, P.; Blanke, Mogens; P. Castaldi; Mimmo, N.; S. Simani

    2016-01-01

    This paper presents a novel scheme for diagnosis of faults affecting the sensors measuring the satellite attitude, body angular velocity and flywheel spin rates as well as defects related to the control torques provided by satellite reaction wheels. A nonlinear geometric design is used to avoid that aerodynamic disturbance torques have unwanted influence on the residuals exploited for fault detection and isolation. Radial basis function neural networks are used to obtain fault estimation filt...

  11. A DISTRIBUTED QOS ROUTING BASED ON ANT ALGORITHM FOR LEO SATELLITE NETWORK

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Low Earth Orbit (LEO) satellites provide short round-trip delays and are becoming increasingly important. One of the challenges in LEO satellite networks is the development of specialized and efficient routing algorithms. To satisfy the QoS requirements of multimedia applications, satellite routing protocols should consider handovers and minimize their effect on the active connections. A distributed QoS routing scheme based on heuristic ant algorithm is proposed for satisfying delay bound and avoiding link congestion. Simulation results show that the call blocking probabilities of this algorithm are less than that of Shortest Path First (SPF) with different delay bound.

  12. Combined Geometric and Neural Network Approach to Generic Fault Diagnosis in Satellite Actuators and Sensors

    DEFF Research Database (Denmark)

    Baldi, P.; Blanke, Mogens; Castaldi, P.;

    2016-01-01

    This paper presents a novel scheme for diagnosis of faults affecting the sensors measuring the satellite attitude, body angular velocity and flywheel spin rates as well as defects related to the control torques provided by satellite reaction wheels. A nonlinear geometric design is used to avoid...... that aerodynamic disturbance torques have unwanted influence on the residuals exploited for fault detection and isolation. Radial basis function neural networks are used to obtain fault estimation filters that do not need a priori information about the fault internal models. Simulation results are based...... on a detailed nonlinear satellite model with embedded disturbance description. The results document the efficacy of the proposed diagnosis scheme....

  13. A COMBINED ADMISSION CONTROL ALGORITHM WITH DA PROTOCOL FOR SATELLITE ATM NETWORKS

    Institute of Scientific and Technical Information of China (English)

    Lu Rong; Cao Zhigang

    2006-01-01

    Admission control is an important strategy for Quality of Service (QoS) provisioning in Asynchronous Transfer Mode (ATM) networks. Based on a control-theory model of resources on-Demand Allocation (DA) protocol, the paper studies the effect of the protocol on the statistical characteristics of network traffic,and proposes a combined connection admission control algorithm with the DA protocol to achieve full utilization of link resources in satellite communication systems. The proposed algorithm is based on the cross-layer-design approach. Theoretical analysis and system simulation results show that the proposed algorithm can admit more connections within certain admission thresholds than one that does not take into account the DA protocol. Thus, the proposed algorithm can increase admission ratio of traffic sources for satellite ATM networks and improve satellite link utilization.

  14. Dynamic communications for small satellites using disruption tolerant network concepts

    NARCIS (Netherlands)

    Giuditta, N.; Gill, E.K.A.; Fernández, B.; Isaac, D.

    2009-01-01

    New network technologies are providing interconnectivity in areas previously unheard of. One of these novel technologies, named Disruption Tolerant Networking (DTN), shows promise for the space industry. In order to study its suitability for University projects, a model of a University space mission

  15. Chinese Surveying and Control Network for Earth-Orbit Satellites and Deep Space Detection

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The relationship between the surveying and control network(CSN) for earth-orbit satellite and spatial geodesy, and the relationship between the CSN for deep space celestial bodies and detectors, and deep space detection are briefly summarized, and so are the basic technical needs of the deep space surveying and control network(DSN). Then, the techniques, the constituents and the distributing of Chinese satellite CSN (CSCSN) and other radio observing establishments in China are introduced. Lastly, with the primary CSCSN and other observing establishments, some projects for China to rebuild a more perfect CSCSN, and to establish a DSN are analyzed and stated.

  16. Space Network IP Services (SNIS): An Architecture for Supporting Low Earth Orbiting IP Satellite Missions

    Science.gov (United States)

    Israel, David J.

    2005-01-01

    The NASA Space Network (SN) supports a variety of missions using the Tracking and Data Relay Satellite System (TDRSS), which includes ground stations in White Sands, New Mexico and Guam. A Space Network IP Services (SNIS) architecture is being developed to support future users with requirements for end-to-end Internet Protocol (IP) communications. This architecture will support all IP protocols, including Mobile IP, over TDRSS Single Access, Multiple Access, and Demand Access Radio Frequency (RF) links. This paper will describe this architecture and how it can enable Low Earth Orbiting IP satellite missions.

  17. Performance Analysis of Integrated Wireless Sensor and Multibeam Satellite Networks Under Terrestrial Interference

    Directory of Open Access Journals (Sweden)

    Hongjun Li

    2016-10-01

    Full Text Available This paper investigates the performance of integrated wireless sensor and multibeam satellite networks (IWSMSNs under terrestrial interference. The IWSMSNs constitute sensor nodes (SNs, satellite sinks (SSs, multibeam satellite and remote monitoring hosts (RMHs. The multibeam satellite covers multiple beams and multiple SSs in each beam. The SSs can be directly used as SNs to transmit sensing data to RMHs via the satellite, and they can also be used to collect the sensing data from other SNs to transmit to the RMHs. We propose the hybrid one-dimensional (1D and 2D beam models including the equivalent intra-beam interference factor β from terrestrial communication networks (TCNs and the equivalent inter-beam interference factor α from adjacent beams. The terrestrial interference is possibly due to the signals from the TCNs or the signals of sinks being transmitted to other satellite networks. The closed-form approximations of capacity per beam are derived for the return link of IWSMSNs under terrestrial interference by using the Haar approximations where the IWSMSNs experience the Rician fading channel. The optimal joint decoding capacity can be considered as the upper bound where all of the SSs’ signals can be jointly decoded by a super-receiver on board the multibeam satellite or a gateway station that knows all of the code books. While the linear minimum mean square error (MMSE capacity is where all of the signals of SSs are decoded singularly by a multibeam satellite or a gateway station. The simulations show that the optimal capacities are obviously higher than the MMSE capacities under the same conditions, while the capacities are lowered by Rician fading and converge as the Rician factor increases. α and β jointly affect the performance of hybrid 1D and 2D beam models, and the number of SSs also contributes different effects on the optimal capacity and MMSE capacity of the IWSMSNs.

  18. Performance Analysis of Integrated Wireless Sensor and Multibeam Satellite Networks Under Terrestrial Interference.

    Science.gov (United States)

    Li, Hongjun; Yin, Hao; Gong, Xiangwu; Dong, Feihong; Ren, Baoquan; He, Yuanzhi; Wang, Jingchao

    2016-10-14

    This paper investigates the performance of integrated wireless sensor and multibeam satellite networks (IWSMSNs) under terrestrial interference. The IWSMSNs constitute sensor nodes (SNs), satellite sinks (SSs), multibeam satellite and remote monitoring hosts (RMHs). The multibeam satellite covers multiple beams and multiple SSs in each beam. The SSs can be directly used as SNs to transmit sensing data to RMHs via the satellite, and they can also be used to collect the sensing data from other SNs to transmit to the RMHs. We propose the hybrid one-dimensional (1D) and 2D beam models including the equivalent intra-beam interference factor β from terrestrial communication networks (TCNs) and the equivalent inter-beam interference factor α from adjacent beams. The terrestrial interference is possibly due to the signals from the TCNs or the signals of sinks being transmitted to other satellite networks. The closed-form approximations of capacity per beam are derived for the return link of IWSMSNs under terrestrial interference by using the Haar approximations where the IWSMSNs experience the Rician fading channel. The optimal joint decoding capacity can be considered as the upper bound where all of the SSs' signals can be jointly decoded by a super-receiver on board the multibeam satellite or a gateway station that knows all of the code books. While the linear minimum mean square error (MMSE) capacity is where all of the signals of SSs are decoded singularly by a multibeam satellite or a gateway station. The simulations show that the optimal capacities are obviously higher than the MMSE capacities under the same conditions, while the capacities are lowered by Rician fading and converge as the Rician factor increases. α and β jointly affect the performance of hybrid 1D and 2D beam models, and the number of SSs also contributes different effects on the optimal capacity and MMSE capacity of the IWSMSNs.

  19. Requirements analysis and design for implementation of a satellite link for a local area computer network

    OpenAIRE

    Lorentzen, Richard B.

    1991-01-01

    Approved for public release; distribution is unlimited The purpose of this thesis is to provide naval computer students with a basic knowledge on Very Small Aperture Terminal (VSAT) satellite technology and to define the hardware and software requirements at the interface between a VSAT and a Local Area Network (LAN). By restricting a computer network to terrestrial links, a vast amount of knowledge is not accessed because either the terrestrial links can't access the information or the...

  20. Protocol Support for a New Satellite-Based Airspace Communication Network

    Science.gov (United States)

    Shang, Yadong; Hadjitheodosiou, Michael; Baras, John

    2004-01-01

    We recommend suitable transport protocols for an aeronautical network supporting Internet and data services via satellite. We study the characteristics of an aeronautical satellite hybrid network and focus on the problems that cause dramatically degraded performance of the Transport Protocol. We discuss various extensions to standard TCP that alleviate some of these performance problems. Through simulation, we identify those TCP implementations that can be expected to perform well. Based on the observation that it is difficult for an end-to-end solution to solve these problems effectively, we propose a new TCP-splitting protocol, termed Aeronautical Transport Control Protocol (AeroTCP). The main idea of this protocol is to use a fixed window for flow control and one duplicated acknowledgement (ACK) for fast recovery. Our simulation results show that AeroTCP can maintain higher utilization for the satellite link than end-to-end TCP, especially in high BER environment.

  1. A Handover Strategy in the LEO Satellite-Based Constellation Networks with ISLs

    Institute of Scientific and Technical Information of China (English)

    LIU Gang; GOU Dingyong; WU Shiqi

    2003-01-01

    A new handover strategy named minimal-hops handover(MHH) strategy for the low earth orbit(LEO) satellite constellations networks equipped with inter-satellite links(ISLs) is proposed.MHH strategy, which is based on the hops of the end-to-end connection paths and makes good use of the regularity of the constellation network topology, can appropriately combine the handover procedure with routing and efficiently solve the inter-satellite handover issue. Moreover, MHH strategy can provide quality of services( QoS) guarantees to some extent. The system performances of the MHH strategy, such as time propagation delay and handover frequency, are evaluated and compared with that of other previous strategies. The simulation results show that MHH strategy performs better than other previous handover strategies.

  2. The performance evaluation of a new neural network based traffic management scheme for a satellite communication network

    Science.gov (United States)

    Ansari, Nirwan; Liu, Dequan

    1991-01-01

    A neural-network-based traffic management scheme for a satellite communication network is described. The scheme consists of two levels of management. The front end of the scheme is a derivation of Kohonen's self-organization model to configure maps for the satellite communication network dynamically. The model consists of three stages. The first stage is the pattern recognition task, in which an exemplar map that best meets the current network requirements is selected. The second stage is the analysis of the discrepancy between the chosen exemplar map and the state of the network, and the adaptive modification of the chosen exemplar map to conform closely to the network requirement (input data pattern) by means of Kohonen's self-organization. On the basis of certain performance criteria, whether a new map is generated to replace the original chosen map is decided in the third stage. A state-dependent routing algorithm, which arranges the incoming call to some proper path, is used to make the network more efficient and to lower the call block rate. Simulation results demonstrate that the scheme, which combines self-organization and the state-dependent routing mechanism, provides better performance in terms of call block rate than schemes that only have either the self-organization mechanism or the routing mechanism.

  3. The method of the antenna system positioning for satellite communication network radiomonitoring complex

    OpenAIRE

    Гребенюк, Олег Петрович

    2014-01-01

    The method of orientation of the antenna system of complex of radiomonitoring of satellite communication networks is offered. A method takes into account the features of construction and functional setting of a transport stream of standard of DVB ‑ S.

  4. TOLNet - A Tropospheric Ozone Lidar Profiling Network for Satellite Continuity and Process Studies

    Science.gov (United States)

    Newchurch, Michael J.; Kuang, Shi; Wang, Lihua; LeBlanc, Thierry; Alvarez II, Raul J.; Langford, Andrew O.; Senff, Christoph J.; Brown, Steve; Johnson, Bryan; Burris, John F.; hide

    2015-01-01

    NASA initiated an interagency ozone lidar observation network under the name TOLNet to promote cooperative multiple-station ozone-lidar observations to provide highly time-resolved (few minutes) tropospheric-ozone vertical profiles useful for air-quality studies, model evaluation, and satellite validation.

  5. Geometric Aspects of Ground Augmentation of Satellite Networks for the Needs of Deformation Monitoring

    Science.gov (United States)

    Protaziuk, Elżbieta

    2016-06-01

    Satellite measurements become competitive in many tasks of engineering surveys, however, in many requiring applications possibilities to apply such solutions are still limited. The possibility to widely apply satellite technologies for displacements measurements is related with new challenges; the most important of them relate to increasing requirements concerning the accuracy, reliability and continuity of results of position determination. One of the solutions is a ground augmentation of satellite network, which intention is to improve precision of positioning, ensure comparable accuracy of coordinates and reduce precision fluctuations over time. The need for augmentation of GNSS is particularly significant in situations: where the visibility of satellites is poor because of terrain obstacles, when the determined position is not precise enough or a satellites constellation does not allow for reliable positioning. Ground based source/sources of satellite signal placed at a ground, called pseudosatellites, or pseudolites were intensively investigated during the last two decades and finally were developed into groundbased, time-synchronized transceivers, that can transmit and receive a proprietary positioning signal. The paper presents geometric aspects of the ground based augmentation of the satellite networks using various quality measures of positioning geometry, which depends on access to the constellation of satellites and the conditions of the observation environment. The issue of minimizing these measures is the key problem that allows to obtain the position with high accuracy. For this purpose, the use of an error ellipsoid is proposed and compared with an error ellipse. The paper also describes the results of preliminary accuracy analysis obtained at test area and a comparison of various measures of the quality of positioning geometry.

  6. Neural network based satellite tracking for deep space applications

    Science.gov (United States)

    Amoozegar, F.; Ruggier, C.

    2003-01-01

    The objective of this paper is to provide a survey of neural network trends as applied to the tracking of spacecrafts in deep space at Ka-band under various weather conditions and examine the trade-off between tracing accuracy and communication link performance.

  7. A gradual neural-network approach for frequency assignment in satellite communication systems.

    Science.gov (United States)

    Funabiki, N; Nishikawa, S

    1997-01-01

    A novel neural-network approach called gradual neural network (GNN) is presented for a class of combinatorial optimization problems of requiring the constraint satisfaction and the goal function optimization simultaneously. The frequency assignment problem in the satellite communication system is efficiently solved by GNN as the typical problem of this class. The goal of this NP-complete problem is to minimize the cochannel interference between satellite communication systems by rearranging the frequency assignment so that they can accommodate the increasing demands. The GNN consists of NxM binary neurons for the N-carrier-M-segment system with the gradual expansion scheme of activated neurons. The binary neural network achieves the constrain satisfaction with the help of heuristic methods, whereas the gradual expansion scheme seeks the cost optimization. The capability of GNN is demonstrated through solving 15 instances in practical size systems, where GNN can find far better solutions than the existing algorithm.

  8. Networked Operations of Hybrid Radio Optical Communications Satellites

    Science.gov (United States)

    Hylton, Alan; Raible, Daniel

    2014-01-01

    In order to address the increasing communications needs of modern equipment in space, and to address the increasing number of objects in space, NASA is demonstrating the potential capability of optical communications for both deep space and near-Earth applications. The Integrated Radio Optical Communications (iROC) is a hybrid communications system that capitalizes on the best of both the optical and RF domains while using each technology to compensate for the other's shortcomings. Specifically, the data rates of the optical links can be higher than their RF counterparts, whereas the RF links have greater link availability. The focus of this paper is twofold: to consider the operations of one or more iROC nodes from a networking point of view, and to suggest specific areas of research to further the field. We consider the utility of Disruption Tolerant Networking (DTN) and the Virtual Mission Operation Center (VMOC) model.

  9. ISI's Journal Citation Reports on the Web.

    Science.gov (United States)

    Fitzpatrick, Roberta Bronson

    2003-01-01

    This column features an overview of the Institute for Scientific Information's (ISI) Journal Citation Reports (JCR) database. Basic searching techniques are presented, as well as simple ways to manipulate data contained in the file. The Journal Citation Reports database can provide information on highest impact journals, most frequently used journals, "hottest" journals, and largest journals in a field or discipline.

  10. Amazon Rainforest Deforestation Daily Detection Tool Using Artificial Neural Networks and Satellite Images

    Directory of Open Access Journals (Sweden)

    Silvio César Cazella

    2012-10-01

    Full Text Available The main purpose of this work was the development of a tool to detect daily deforestation in the Amazon rainforest, using satellite images from the MODIS/TERRA [1] sensor and Artificial Neural Networks. The developed tool provides the parameterization of the configuration for the neural network training to enable us to find the best neural architecture to address the problem. The tool makes use of confusion matrixes to determine the degree of success of the network. Part of the municipality of Porto Velho, in Rondônia state, is located inside the tile H11V09 of the MODIS/TERRA sensor, which was used as the study area. A spectrum-temporal analysis of this area was made on 57 images from 20 of May to 15 of July 2003 using the trained neural network. This analysis allowed us to verify the quality of the implemented neural network classification as well as helping our understanding of the dynamics of deforestation in the Amazon rainforest. The great potential of neural networks for image classification was perceived with this work. However, the generation of consistent alarms, in other words, detecting predatory actions at the beginning; instead of firing false alarms is a complex task that has not yet been solved. Therefore, the major contribution of this paper is to provide a theoretical basis and practical use of neural networks and satellite images to combat illegal deforestation.

  11. Research on handover algorithm to reduce the blocking probability in LEO satellite network

    Institute of Scientific and Technical Information of China (English)

    Chen Bingcai; Zhang Naitong; Nie Boxun; Zhou Tingxian

    2006-01-01

    Based on the characteristics of guaranteed handover (GH) algorithm, the finite capacity in one system makes the blocking probability (PB) of GH algorithm increase rapidly in the case of high traffic load. So, when large amounts of multimedia services are transmitted via a single low earth orbit (LEO) satellite system, the PB of it is much higher. In order to solve the problem, a novel handover scheme defined by multi-tier optiral layer selection is proposed. The scheme sufficienfly takes into ac count the characteristics of double-tier satellite network, which is constituted by LEO satellites combined with medium earth orbit (MEO) satellites, and the multimedia transmitted by such network, so it can augment this systematic capacity and effectively reduces the traffic load in the LEO which performs GH algorithm. The detailed processes are also presented. The simulation and numerical results show that the approach integrated with GH algorithm achieves a significant improvement in the PB and practicability, as compared to the single LEO layer network.

  12. TOLNET – A Tropospheric Ozone Lidar Profiling Network for Satellite Continuity and Process Studies

    Directory of Open Access Journals (Sweden)

    Newchurch Michael J.

    2016-01-01

    Full Text Available Ozone lidars measure continuous, high-resolution ozone profiles critical for process studies and for satellite validation in the lower troposphere. However, the effectiveness of lidar validation by using single-station data is limited. Recently, NASA initiated an interagency ozone lidar observation network under the name TOLNet to promote cooperative multiple-station ozone-lidar observations to provide highly timeresolved (few minutes tropospheric-ozone vertical profiles useful for air-quality studies, model evaluation, and satellite validation. This article briefly describes the concept, stations, major specifications of the TOLNet instruments, and data archiving.

  13. Diversity reception for advanced multi-satellite networks: A CDMA approach

    Science.gov (United States)

    Colzi, E.; Degaudenzi, R.; Elia, C.; Giannetti, F.; Viola, R.

    1993-01-01

    Diversity reception for Synchronous CDMA (S-CDMA) is introduced and analyzed. A Gaussian co-channel synchronous and asynchronous interference approximation is derived to evaluate the effects on the system bit error rate. Numerical results are provided for a simple mobile communication system where the signals transmitted by two distinct satellites in visibility are coherently combined by a three fingers Rake receiver. A second example showing performance of an integrated ground/satellite single frequency network for digital audio broadcasting is presented. Results show the capacity advantage of utilizing S-CDMA in combination with diversity reception.

  14. Satellite image processing for precision agriculture and agroindustry using convolutional neural network and genetic algorithm

    Science.gov (United States)

    Firdaus; Arkeman, Y.; Buono, A.; Hermadi, I.

    2017-01-01

    Translating satellite imagery to a useful data for decision making during this time are usually done manually by human. In this research, we are going to translate satellite imagery by using artificial intelligence method specifically using convolutional neural network and genetic algorithm to become a useful data for decision making, especially for precision agriculture and agroindustry. In this research, we are focused on how to made a sustainable land use planning with 3 objectives. The first is maximizing economic factor. Second is minimizing CO2 emission and the last is minimizing land degradation. Results show that by using artificial intelligence method, can produced a good pareto optimum solutions in a short time.

  15. Diversity reception for advanced multi-satellite networks: A CDMA approach

    Science.gov (United States)

    Colzi, E.; Degaudenzi, R.; Elia, C.; Giannetti, F.; Viola, R.

    Diversity reception for Synchronous CDMA (S-CDMA) is introduced and analyzed. A Gaussian co-channel synchronous and asynchronous interference approximation is derived to evaluate the effects on the system bit error rate. Numerical results are provided for a simple mobile communication system where the signals transmitted by two distinct satellites in visibility are coherently combined by a three fingers Rake receiver. A second example showing performance of an integrated ground/satellite single frequency network for digital audio broadcasting is presented. Results show the capacity advantage of utilizing S-CDMA in combination with diversity reception.

  16. Satellite Radar Interferometry For Risk Management Of Gas Pipeline Networks

    Science.gov (United States)

    Ianoschi, Raluca; Schouten, Mathijs; Bas Leezenberg, Pieter; Dheenathayalan, Prabu; Hanssen, Ramon

    2013-12-01

    InSAR time series analyses can be fine-tuned for specific applications, yielding a potential increase in benchmark density, precision and reliability. Here we demonstrate the algorithms developed for gas pipeline monitoring, enabling operators to precisely pinpoint unstable locations. This helps asset management in planning, prioritizing and focusing in-situ inspections, thus reducing maintenance costs. In unconsolidated Quaternary soils, ground settlement contributes to possible failure of brittle cast iron gas pipes and their connections to houses. Other risk factors include the age and material of the pipe. The soil dynamics have led to a catastrophic explosion in the city of Amsterdam, which triggered an increased awareness for the significance of this problem. As the extent of the networks can be very wide, InSAR is shown to be a valuable source of information for identifying the hazard regions. We monitor subsidence affecting an urban gas transportation network in the Netherlands using both medium and high resolution SAR data. Results for the 2003-2010 period provide clear insights on the differential subsidence rates in the area. This enables characterization of underground motion that affects the integrity of the pipeline. High resolution SAR data add extra detail of door-to-door pipeline connections, which are vulnerable due to different settlements between house connections and main pipelines. The rates which we measure represent important input in planning of maintenance works. Managers can decide the priority and timing for inspecting the pipelines. The service helps manage the risk and reduce operational cost in gas transportation networks.

  17. Extraction of DTM from Satellite Images Using Neural Networks

    OpenAIRE

    Tapper, Gustav

    2016-01-01

    This thesis presents a way to generate a Digital Terrain Model (dtm) from a Digital Surface Model (dsm) and multi spectral images (including the Near Infrared (nir) color band). An Artificial Neural Network (ann) is used to pre-classify the dsm and multi spectral images. This in turn is used to filter the dsm to a dtm. The use of an ann as a classifier provided good results. Additionally, the addition of the nir color band resulted in an improvement of the accuracy of the classifier. Using th...

  18. Ku-band satellite data networks using very small aperture terminals. II - System design

    Science.gov (United States)

    Raychaudhuri, D.

    1987-12-01

    An overview is presented of system design for Ku-band star networks intended for interactive data applications. The component elements of such a network are discussed, and the critical items for performance, capacity, and cost are identified. A systematic design procedure combining delay-throughput characterization of the multiaccess inbound and TDM outbound channels with satellite link analysis is provided by which system components and their parameters are selected once the network response time and availability objectives are specified. The results are presented in the form of charts and tables which may serve as the basis for star network design over a range of typical traffic models, component parameters, and performance objectives. The methodology is potentially useful for evaluating alternative network architectures and traffic scenarios which may become important as VSAT technology evolves.

  19. Dynamic autonomous routing technology for IP-based satellite ad hoc networks

    Science.gov (United States)

    Wang, Xiaofei; Deng, Jing; Kostas, Theresa; Rajappan, Gowri

    2014-06-01

    IP-based routing for military LEO/MEO satellite ad hoc networks is very challenging due to network and traffic heterogeneity, network topology and traffic dynamics. In this paper, we describe a traffic priority-aware routing scheme for such networks, namely Dynamic Autonomous Routing Technology (DART) for satellite ad hoc networks. DART has a cross-layer design, and conducts routing and resource reservation concurrently for optimal performance in the fluid but predictable satellite ad hoc networks. DART ensures end-to-end data delivery with QoS assurances by only choosing routing paths that have sufficient resources, supporting different packet priority levels. In order to do so, DART incorporates several resource management and innovative routing mechanisms, which dynamically adapt to best fit the prevailing conditions. In particular, DART integrates a resource reservation mechanism to reserve network bandwidth resources; a proactive routing mechanism to set up non-overlapping spanning trees to segregate high priority traffic flows from lower priority flows so that the high priority flows do not face contention from low priority flows; a reactive routing mechanism to arbitrate resources between various traffic priorities when needed; a predictive routing mechanism to set up routes for scheduled missions and for anticipated topology changes for QoS assurance. We present simulation results showing the performance of DART. We have conducted these simulations using the Iridium constellation and trajectories as well as realistic military communications scenarios. The simulation results demonstrate DART's ability to discriminate between high-priority and low-priority traffic flows and ensure disparate QoS requirements of these traffic flows.

  20. Satellite clock corrections estimation to accomplish real time ppp: experiments for brazilian real time network

    Science.gov (United States)

    Marques, Haroldo; Monico, João; Aquino, Marcio; Melo, Weyller

    2014-05-01

    The real time PPP method requires the availability of real time precise orbits and satellites clocks corrections. Currently, it is possible to apply the solutions of clocks and orbits available by BKG within the context of IGS Pilot project or by using the operational predicted IGU ephemeris. The accuracy of the satellite position available in the IGU is enough for several applications requiring good quality. However, the satellites clocks corrections do not provide enough accuracy (3 ns ~ 0.9 m) to accomplish real time PPP with the same level of accuracy. Therefore, for real time PPP application it is necessary to further research and develop appropriated methodologies for estimating the satellite clock corrections in real time with better accuracy. Currently, it is possible to apply the real time solutions of clocks and orbits available by Federal Agency for Cartography and Geodesy (BKG) within the context of IGS Pilot project. The BKG corrections are disseminated by a new proposed format of the RTCM 3.x and can be applied in the broadcasted orbits and clocks. Some investigations have been proposed for the estimation of the satellite clock corrections using GNSS code and phase observable at the double difference level between satellites and epochs (MERVAT, DOUSA, 2007). Another possibility consists of applying a Kalman Filter in the PPP network mode (HAUSCHILD, 2010) and it is also possible the integration of both methods, using network PPP and observables at double difference level in specific time intervals (ZHANG; LI; GUO, 2010). For this work the methodology adopted consists in the estimation of the satellite clock corrections based on the data adjustment in the PPP mode, but for a network of GNSS stations. The clock solution can be solved by using two types of observables: code smoothed by carrier phase or undifferenced code together with carrier phase. In the former, we estimate receiver clock error; satellite clock correction and troposphere, considering

  1. SM_TCP: a new reliable multicast transport protocol for satellite IP networks

    Science.gov (United States)

    Liu, Gongliang; Gu, Xuemai; Li, Shizhong

    2005-11-01

    A new reliable multicast transport protocol SM_TCP is proposed for satellite IP networks in this paper. In SM_TCP, the XOR scheme with the aid of on-board buffering and processing is used for error recovery and an optimal retransmission algorithm is designed, which can reduce the recovery time by half of the RTT and minimize the number of retransmissions. In order to avoid the unnecessary decrease of congestion window in the high BER satellite channels, the occupied buffer sizes at bottlenecks are measured in adjusting the congestion window, instead of depending on the packet loss information. The average session rate of TCP sessions and of multicast sessions passing through the satellite are also measured and compared in adjusting the congestion window, which contributes to bandwidth fairness. Analysis and simulation results show fairness with TCP flows and scalability.

  2. A Topology Control Strategy with Reliability Assurance for Satellite Cluster Networks in Earth Observation.

    Science.gov (United States)

    Chen, Qing; Zhang, Jinxiu; Hu, Ze

    2017-02-23

    This article investigates the dynamic topology control problemof satellite cluster networks (SCNs) in Earth observation (EO) missions by applying a novel metric of stability for inter-satellite links (ISLs). The properties of the periodicity and predictability of satellites' relative position are involved in the link cost metric which is to give a selection criterion for choosing the most reliable data routing paths. Also, a cooperative work model with reliability is proposed for the situation of emergency EO missions. Based on the link cost metric and the proposed reliability model, a reliability assurance topology control algorithm and its corresponding dynamic topology control (RAT) strategy are established to maximize the stability of data transmission in the SCNs. The SCNs scenario is tested through some numeric simulations of the topology stability of average topology lifetime and average packet loss rate. Simulation results show that the proposed reliable strategy applied in SCNs significantly improves the data transmission performance and prolongs the average topology lifetime.

  3. A space weather forecasting system with multiple satellites based on a self-recognizing network.

    Science.gov (United States)

    Tokumitsu, Masahiro; Ishida, Yoshiteru

    2014-05-05

    This paper proposes a space weather forecasting system at geostationary orbit for high-energy electron flux (>2 MeV). The forecasting model involves multiple sensors on multiple satellites. The sensors interconnect and evaluate each other to predict future conditions at geostationary orbit. The proposed forecasting model is constructed using a dynamic relational network for sensor diagnosis and event monitoring. The sensors of the proposed model are located at different positions in space. The satellites for solar monitoring equip with monitoring devices for the interplanetary magnetic field and solar wind speed. The satellites orbit near the Earth monitoring high-energy electron flux. We investigate forecasting for typical two examples by comparing the performance of two models with different numbers of sensors. We demonstrate the prediction by the proposed model against coronal mass ejections and a coronal hole. This paper aims to investigate a possibility of space weather forecasting based on the satellite network with in-situ sensing.

  4. A Space Weather Forecasting System with Multiple Satellites Based on a Self-Recognizing Network

    Directory of Open Access Journals (Sweden)

    Masahiro Tokumitsu

    2014-05-01

    Full Text Available This paper proposes a space weather forecasting system at geostationary orbit for high-energy electron flux (>2 MeV. The forecasting model involves multiple sensors on multiple satellites. The sensors interconnect and evaluate each other to predict future conditions at geostationary orbit. The proposed forecasting model is constructed using a dynamic relational network for sensor diagnosis and event monitoring. The sensors of the proposed model are located at different positions in space. The satellites for solar monitoring equip with monitoring devices for the interplanetary magnetic field and solar wind speed. The satellites orbit near the Earth monitoring high-energy electron flux. We investigate forecasting for typical two examples by comparing the performance of two models with different numbers of sensors. We demonstrate the prediction by the proposed model against coronal mass ejections and a coronal hole. This paper aims to investigate a possibility of space weather forecasting based on the satellite network with in-situ sensing.

  5. Aviation-oriented Mobility Management Method in IP/LEO Satellite Networks

    Institute of Scientific and Technical Information of China (English)

    Guo Xin; Zhang Jun; Zhang Tao; Ding Yanwen

    2008-01-01

    Taking into chief consideration the features of aviation nodes in satellite networks,such as high moving speed,long communication distance,and high connection frequency,this article proposes an aviatiun-oriented mobility management method for IP/low earth orbit (LEO) satellite networks.By introducing the concept of ground station real-time coverage area,the proposed method uses ground-station-based IP addressing method and cell paging scheme to decrease the frequency of IP binding update requests as well as the paging cost.In comparison with the paging mobile IP (P-MIP) method and the handover-independent IP mobility management method,as is verified by the mathematical analysis and simulation,the proposed method could decrease the management cost.It also possesses better ability to support the aviation nodes because it is subjected to fewer influences from increased node speeds and newly coming connection rates.

  6. A university-based distributed satellite mission control network for operating professional space missions

    Science.gov (United States)

    Kitts, Christopher; Rasay, Mike

    2016-03-01

    For more than a decade, Santa Clara University's Robotic Systems Laboratory has operated a unique, distributed, internet-based command and control network for providing professional satellite mission control services for a variety of government and industry space missions. The system has been developed and is operated by students who become critical members of the mission teams throughout the development, test, and on-orbit phases of these missions. The mission control system also supports research in satellite control technology and hands-on student aerospace education. This system serves as a benchmark for its comprehensive nature, its student-centric nature, its ability to support NASA and industry space missions, and its longevity in providing a consistent level of professional services. This paper highlights the unique features of this program, reviews the network's design and the supported spacecraft missions, and describes the critical programmatic features of the program that support the control of professional space missions.

  7. Reconstruction of an infrared band of meteorological satellite imagery with abductive networks

    Science.gov (United States)

    Singer, Harvey A.; Cockayne, John E.; Versteegen, Peter L.

    1995-01-01

    As the current fleet of meteorological satellites age, the accuracy of the imagery sensed on a spectral channel of the image scanning system is continually and progressively degraded by noise. In time, that data may even become unusable. We describe a novel approach to the reconstruction of the noisy satellite imagery according to empirical functional relationships that tie the spectral channels together. Abductive networks are applied to automatically learn the empirical functional relationships between the data sensed on the other spectral channels to calculate the data that should have been sensed on the corrupted channel. Using imagery unaffected by noise, it is demonstrated that abductive networks correctly predict the noise-free observed data.

  8. A hybrid hopfield network-simulated annealing approach for frequency assignment in satellite communications systems.

    Science.gov (United States)

    Salcedo-Sanz, Sancho; Santiago-Mozos, Ricardo; Bousoño-Calzón, Carlos

    2004-04-01

    A hybrid Hopfield network-simulated annealing algorithm (HopSA) is presented for the frequency assignment problem (FAP) in satellite communications. The goal of this NP-complete problem is minimizing the cochannel interference between satellite communication systems by rearranging the frequency assignment, for the systems can accommodate the increasing demands. The HopSA algorithm consists of a fast digital Hopfield neural network which manages the problem constraints hybridized with a simulated annealing which improves the quality of the solutions obtained. We analyze the problem and its formulation, describing and discussing the HopSA algorithm and solving a set of benchmark problems. The results obtained are compared with other existing approaches in order to show the performance of the HopSA approach.

  9. Classification and Segmentation of Satellite Orthoimagery Using Convolutional Neural Networks

    Directory of Open Access Journals (Sweden)

    Martin Längkvist

    2016-04-01

    Full Text Available The availability of high-resolution remote sensing (HRRS data has opened up the possibility for new interesting applications, such as per-pixel classification of individual objects in greater detail. This paper shows how a convolutional neural network (CNN can be applied to multispectral orthoimagery and a digital surface model (DSM of a small city for a full, fast and accurate per-pixel classification. The predicted low-level pixel classes are then used to improve the high-level segmentation. Various design choices of the CNN architecture are evaluated and analyzed. The investigated land area is fully manually labeled into five categories (vegetation, ground, roads, buildings and water, and the classification accuracy is compared to other per-pixel classification works on other land areas that have a similar choice of categories. The results of the full classification and segmentation on selected segments of the map show that CNNs are a viable tool for solving both the segmentation and object recognition task for remote sensing data.

  10. Using Satellite Images for Wireless Network Planing in Baku City

    Science.gov (United States)

    Gojamanov, M.; Ismayilov, J.

    2013-04-01

    It is a well known fact that the Information-Telecommunication and Space research technologies are the fields getting much more benefits from the achievements of the scientific and technical progress. In many cases, these areas supporting each other have improved the conditions for their further development. For instance, the intensive development in the field of the mobile communication has caused the rapid progress of the Space research technologies and vice versa.Today it is impossible to solve one of the most important tasks of the mobile communication as Radio Frecance planning without the 2D and 3D digital maps. The compiling of such maps is much more efficient by means of the space images. Because the quality of the space images has been improved and developed, especially at the both spectral and spatial resolution points. It has been possible to to use 8 Band images with the spatial resolution of 50 sm. At present, in relation to the function 3G of mobile communications one of the main issues facing mobile operator companies is a high-precision 3D digital maps. It should be noted that the number of mobile phone users in the Republic of Azerbaijan went forward other Community of Independent States Countries. Of course, using of aerial images for 3D mapping would be optimal. However, depending on a number of technical and administrative problems aerial photography cannot be used. Therefore, the experience of many countries shows that it will be more effective to use the space images with the higher resolution for these issues. Concerning the fact that the mobile communication within the city of Baku has included 3G function there were ordered stereo images wih the spatial resolution of 50 cm for the 150 sq.km territory occupying the central part of the city in order to compile 3D digital maps. The images collected from the WorldView-2 satellite are 4-Band Bundle(Pan+MS1) stereo images. Such kind of imagery enable to automatically classificate some required

  11. Multi-layered Security Approaches for a Modular Open Network Architecture-based Satellite

    OpenAIRE

    Shirley, Brandon; Young, Quinn; Wegner, Peter; Christensen, Jacob; Janicik, Jeffrey

    2014-01-01

    A growing trend in satellite development includes shortening the development lifecycle for hardware and software, cost reduction, and promoting reuse for future missions. Department of Defense (DoD) acquisition policies mandate system providers use Open Systems Architecture (OSA) where feasible. Modular Open Network Architecture (MONA) is a subset of OSA and paves the way to achieve cost reduction and reuse during a reduced development lifecycle. MONA approaches provide opportunities to enhan...

  12. TCP-ADaLR: TCP with adaptive delay and loss response for broadband GEO satellite networks

    OpenAIRE

    Omueti, Modupe Omogbohun

    2007-01-01

    Transmission Control Protocol (TCP) performance degrades in broadband geostationary satellite networks due to long propagation delays and high bit error rates. In this thesis, we propose TCP with algorithm modifications for adaptive delay and loss response (TCP-ADaLR) to improve TCP performance. TCP-ADaLR incorporates delayed acknowledgement mechanism recommended for Internet hosts. We evaluate and compare the performance of TCP-ADaLR, TCP SACK, and TCP NewReno, with and without delayed ackno...

  13. Defense Science Board Task Force on Military Satellite Communication and Tactical Networking. Executive Summary

    Science.gov (United States)

    2017-03-01

    product of the Defense Science Board (DSB). The DSB is a Federal Advisory Committee established to provide independent advice to the Secretary of Defense...December 2014, the Under Secretary of Defense for Acquisition, Technology, and Logistics (USD(AT&L)) signed the “Terms of Reference – Defense Science ...Board Task Force on Military Satellite Communication and Tactical Networking.” As a result, the Chairman of the Defense Science Board established a

  14. A QoS Architecture for DVB-RCS Next Generation Satellite Networks

    Directory of Open Access Journals (Sweden)

    Gayraud Thierry

    2007-01-01

    Full Text Available The standardization of a return channel via satellite (DVB-RCS and satellite community efforts in term of interoperability over the last few years leads to quite a positive outcome: geostationary satellite networks are intended to provide broadband access to interactive multimedia services in low-infrastructure areas. However, in order to take in account real-time multimedia traffic, an efficient resource management scheme is still necessary to maximize the scarce uplink capacities usage. To address this capacity issue, this paper proposes a complete DVB-RCS QoS architecture that is implemented, thanks to an emulation platform, and evaluated with real multimedia applications. This paper first gives an overview of the QoS architecture usually used in DVB-S/RCS satellite system, especially in layers 2 and 3. It then introduces the satellite system emulation used in the experimentation and its calibration. The main contribution of this work focuses on the signaling principle designed to allow applications to take benefit from the QoS features of the satellite system even if they are non-QoS aware. It is then shown how signaling in such QoS architecture allows the user to change dynamically the QoS of his application using QoS agent and QoS server applications even if the application is not QoS-aware. It is also given quantitative results related to such a dynamic QoS change in the experiments done on the satellite emulation system.

  15. A QoS Architecture for DVB-RCS Next Generation Satellite Networks

    Directory of Open Access Journals (Sweden)

    Pascal Berthou

    2007-12-01

    Full Text Available The standardization of a return channel via satellite (DVB-RCS and satellite community efforts in term of interoperability over the last few years leads to quite a positive outcome: geostationary satellite networks are intended to provide broadband access to interactive multimedia services in low-infrastructure areas. However, in order to take in account real-time multimedia traffic, an efficient resource management scheme is still necessary to maximize the scarce uplink capacities usage. To address this capacity issue, this paper proposes a complete DVB-RCS QoS architecture that is implemented, thanks to an emulation platform, and evaluated with real multimedia applications. This paper first gives an overview of the QoS architecture usually used in DVB-S/RCS satellite system, especially in layers 2 and 3. It then introduces the satellite system emulation used in the experimentation and its calibration. The main contribution of this work focuses on the signaling principle designed to allow applications to take benefit from the QoS features of the satellite system even if they are non-QoS aware. It is then shown how signaling in such QoS architecture allows the user to change dynamically the QoS of his application using QoS agent and QoS server applications even if the application is not QoS-aware. It is also given quantitative results related to such a dynamic QoS change in the experiments done on the satellite emulation system.

  16. ISIS Technologies for Smart Civil Engineering Infrastructure

    Institute of Scientific and Technical Information of China (English)

    Aftab A. Mufti; Kenneth W. Neale

    2004-01-01

    For more than a century, important civil engineering structures such as bridges, high-rise buildings, dams and marine platforms have contained iron or steel as the reinforcement for concrete or wood (ISIS Canada Strategic Plan, 2000). The useful lives of such structures have often been severely limited by the corrosion of this ferrous component. Much thought has been given in recent years to constructing structures that are lighter, stronger and non-corrosive. These innovative structures are new and for these to be accepted by the engineering community monitoring is mandatory. ISIS Canada has been developing such structures and monitoring them. In this paper, innovative bridge decks that have been implemented is described.

  17. UNSUPERVISED CLASSIFICATION OF HIGH RESOLUTION SATELLITE IMAGERY BY SELF-ORGANIZING NEURAL NETWORK

    Directory of Open Access Journals (Sweden)

    ÁRPÁD BARSI

    2010-06-01

    Full Text Available The current paper discusses the importance of the modern high resolution satellite imagery. The acquired high amount of data must be processed by an efficient way, where the used Kohonen-type self-organizing map has been proven as a suitable tool. The paper gives an introduction to this interesting method. The tests have shown that the multispectral image information can be taken after a resampling step as neural network inputs, and then the derived network weights are able to evaluate the whole image with acceptable thematic accuracy.

  18. World-wide interactive access to scientific databases via satellite and terrestrial data network

    Science.gov (United States)

    Sanderson, T. R.; Albrecht, M. A.; Ciarlo, A.; Brett, M.; Blank, K.; Hughes, P. M. T.; Wallum, G.; Hills, H. K.; Green, J. L.; Mcguire, R. E.; hide

    1990-01-01

    In order to demonstrate the possibilities for scientific networking and data transfer, a first temporary satellite network link was installed between Czecholovakia and the European space operations center in Darmstadt, during the meeting of the inter-agency consultative group for space science in Prague. Several experiments to show interactive nature of the facility and the capability of the system were carried out, and it was proven that, despite the temporary nature of the installation, the planned demonstrations could be conducted in real time. Demonstrations included electronic mail message, orbit prediction and solar X-ray data. The results of the experiment provided insight into possibilities of data exchange.

  19. World-wide interactive access to scientific databases via satellite and terrestrial data network

    Science.gov (United States)

    Sanderson, T. R.; Albrecht, M. A.; Ciarlo, A.; Brett, M.; Blank, K.; Hughes, P. M. T.; Wallum, G.; Hills, H. K.; Green, J. L.; Mcguire, R. E.; Kamei, T.; Kiplinger, A.; Waite, J. H., Jr.

    1990-01-01

    In order to demonstrate the possibilities for scientific networking and data transfer, a first temporary satellite network link was installed between Czecholovakia and the European space operations center in Darmstadt, during the meeting of the inter-agency consultative group for space science in Prague. Several experiments to show interactive nature of the facility and the capability of the system were carried out, and it was proven that, despite the temporary nature of the installation, the planned demonstrations could be conducted in real time. Demonstrations included electronic mail message, orbit prediction and solar X-ray data. The results of the experiment provided insight into possibilities of data exchange.

  20. Proximity graph analysis for linear networks extraction from high-resolution satellite imagery

    Science.gov (United States)

    Skourikhine, Alexei N.

    2006-05-01

    Reliable and accurate methods for detection and extraction of linear network, such as road networks, in satellite imagery are essential to many applications. We present an approach to the road network extraction from high-resolution satellite imagery that is based on proximity graph analysis. We are jumping off from the classification provided by existing spectral and textural classification tools, which produce a set of candidate road patches. Then, constrained Delaunay triangulation and Chordal Axis transform are used to extract centerline characterization of the delineated candidate road patches. We refine produced center lines to reduce noise influence on patch boundaries, resulting in a smaller set of robust center lines authentically representing their road patches. Refined center lines are triangulated using constrained Delaunay triangulation (CDT) algorithm to generate a sub-optimal mesh of interconnections among them. The generated triangle edges connecting different center lines are used for spatial analysis of the center lines relations. A subset of the Delaunay tessellation grid contains the Euclidian Minimum Spanning Tree (EMST) that provides an approximation of road network. The approach can be generalized to the multi-criteria MST and multi-criteria shortest path algorithms to integrate other factors important for road network extraction, in addition to proximity relations considered by standard EMST.

  1. An Ad-hoc Satellite Network to Measure Filamentary Current Structures in the Auroral Zone

    Science.gov (United States)

    Nabong, C.; Fritz, T. A.; Semeter, J. L.

    2014-12-01

    An ad-hoc cubesat-based satellite network project known as ANDESITE is under development at Boston University. It aims to develop a dense constellation of easy-to-use, rapidly-deployable low-cost wireless sensor nodes in space. The objectives of the project are threefold: 1) Demonstrate viability of satellite based sensor networks by deploying an 8-node miniature sensor network to study the filamentation of the field aligned currents in the auroral zones of the Earth's magnetosphere. 2) Test the scalability of proposed protocols, including localization techniques, tracking, data aggregation, and routing, for a 3 dimensional wireless sensor network using a "flock" of nodes. 3) Construct a 6U Cube-sat running the Android OS as an integrated constellation manager, data mule and sensor node deplorer. This small network of sensor nodes will resolve current densities at different spatial resolutions in the near-Earth magnetosphere using measurements from magnetometers with 1-nT sensitivities and 0.2 nT/√Hz self-noise. Mapping of these currents will provide new constraints for models of auroral particle acceleration, wave-particle interactions, ionospheric destabilization, and other kinetic processes operating in the low-beta plasma of the near Earth magnetosphere.

  2. Towards an Autonomous Turbidimeter Network for Multi-Mission Ocean Colour Satellite Data Validation Activities

    Science.gov (United States)

    Dogliotti, A. I.; Nechad, B.; Ruddick, K. G.; Gossn, J. I.

    2016-08-01

    Satellite-based optical sensors such as MODIS/Aqua, Sentinel-2, Sentinel-3, Landsat-8, Pléiades, SABIA/Mar, PROBA-V , etc. can be used to map turbidity and suspended particulate matter in coastal, estuarine and inland waters as support for water quality monitoring, sediment transport applications such as dredging and fisheries science. However, data quality is a critical problem and in situ data must be gathered from a wide range of test sites in order to provide validation for the diverse range of conditions that can be encountered all over the world. In this context, a network to validate satellite turbidity products called TURBINET is proposed with the goal to establish a long-term (autonomous) international network of collaboration and data-sharing. Joint measurements of turbidity, reflectance and in-water side/back-scattering have been performed in Belgium and Argentina in 2015. Instrument comparisons showed that comparable values could be retrieved using different sensors and field measurements were used to validate a Pléiades high resolution image (2m). The results presented in this work demonstrate the feasibility and usefulness of setting up a network to validate satellite turbidity products.

  3. Flaw distribution development from vessel ISI data

    Energy Technology Data Exchange (ETDEWEB)

    Foulds, J.R.; Kennedy, E.L. [Failure Analysis Associates, Inc., Menlo Park, CA (United States); Basin, S.L. [Joyce and Associates, Los Altos, CA (United States); Rosinski, S.T. [Sandia National Labs., Albuquerque, NM (United States)

    1991-12-31

    Previous attempts to develop flaw distributions for use in the structural integrity evaluation of pressurized water reactor (PWR) vessels have aimed at the estimation of a ``generic`` distribution applicable to all vessels. In contrast, this paper describes the analysis of vessel-specific in-service inspection (ISI) data for the development of a flaw distribution reliably representative of the condition of the particular vessel inspected. The application of the methodology may be extended to other vessels, but has been primarily developed for PWR reactor vessels. For this study, the flaw data analyzed included data obtained from three recently performed PWR vessel ISIs and from laboratory inspection of selected weldment sections of the Midland reactor vessel. The variability in both the character of the reviewed data (size range of flaws, number of flaws) and the UT (ultrasonic test) inspection system performance identified a need for analyzing the inspection results on a vessel-, or data set-specific basis. For this purpose, traditional histogram-based methods were inadequate, and a new methodology that can accept a very small number of flaws (typical of vessel-specific ISI results) and that includes consideration of inspection system flaw detection reliability, flaw sizing accuracy and flaw detection threshold, was developed. Results of the application of the methodology to each of the four PWR reactor vessel cases studied are presented and discussed.

  4. Flaw distribution development from vessel ISI data

    Energy Technology Data Exchange (ETDEWEB)

    Foulds, J.R.; Kennedy, E.L. (Failure Analysis Associates, Inc., Menlo Park, CA (United States)); Basin, S.L. (Joyce and Associates, Los Altos, CA (United States)); Rosinski, S.T. (Sandia National Labs., Albuquerque, NM (United States))

    1991-01-01

    Previous attempts to develop flaw distributions for use in the structural integrity evaluation of pressurized water reactor (PWR) vessels have aimed at the estimation of a generic'' distribution applicable to all vessels. In contrast, this paper describes the analysis of vessel-specific in-service inspection (ISI) data for the development of a flaw distribution reliably representative of the condition of the particular vessel inspected. The application of the methodology may be extended to other vessels, but has been primarily developed for PWR reactor vessels. For this study, the flaw data analyzed included data obtained from three recently performed PWR vessel ISIs and from laboratory inspection of selected weldment sections of the Midland reactor vessel. The variability in both the character of the reviewed data (size range of flaws, number of flaws) and the UT (ultrasonic test) inspection system performance identified a need for analyzing the inspection results on a vessel-, or data set-specific basis. For this purpose, traditional histogram-based methods were inadequate, and a new methodology that can accept a very small number of flaws (typical of vessel-specific ISI results) and that includes consideration of inspection system flaw detection reliability, flaw sizing accuracy and flaw detection threshold, was developed. Results of the application of the methodology to each of the four PWR reactor vessel cases studied are presented and discussed.

  5. Detection of land cover change using an Artificial Neural Network on a time-series of MODIS satellite data

    CSIR Research Space (South Africa)

    Olivier, JC

    2007-11-01

    Full Text Available An Artificial Neural Network (ANN) is proposed to detect human-induced land cover change using a sliding window through a time-series of Moderate Resolution Imaging Spectroradiometer (MODIS) satellite surface reflectance pixel values. Training...

  6. Artificial neural network prediction model for geosynchronous electron fluxes: Dependence on satellite position and particle energy

    Science.gov (United States)

    Shin, Dae-Kyu; Lee, Dae-Young; Kim, Kyung-Chan; Hwang, Junga; Kim, Jaehun

    2016-04-01

    Geosynchronous satellites are often exposed to energetic electrons, the flux of which varies often to a large extent. Since the electrons can cause irreparable damage to the satellites, efforts to develop electron flux prediction models have long been made until recently. In this study, we adopt a neural network scheme to construct a prediction model for the geosynchronous electron flux in a wide energy range (40 keV to >2 MeV) and at a high time resolution (as based on 5 min resolution data). As the model inputs, we take the solar wind variables, geomagnetic indices, and geosynchronous electron fluxes themselves. We also take into account the magnetic local time (MLT) dependence of the geosynchronous electron fluxes. We use the electron data from two geosynchronous satellites, GOES 13 and 15, and apply the same neural network scheme separately to each of the GOES satellite data. We focus on the dependence of prediction capability on satellite's magnetic latitude and MLT as well as particle energy. Our model prediction works less efficiently for magnetic latitudes more away from the equator (thus for GOES 13 than for GOES 15) and for MLTs nearer to midnight than noon. The magnetic latitude dependence is most significant for an intermediate energy range (a few hundreds of keV), and the MLT dependence is largest for the lowest energy (40 keV). We interpret this based on degree of variance in the electron fluxes, which depends on magnetic latitude and MLT at geosynchronous orbit as well as particle energy. We demonstrate how substorms affect the flux variance.

  7. Neural network-based recognition of whistlers on spectrograms detected by satellite

    Science.gov (United States)

    Conti, Livio

    2016-04-01

    We present a system to automatically recognize and classify the occurrence of whistler waves on spectrograms of electric field measurements performed by satellite. Whistlers - VLF waves generated by lightning, with a specific spectral dispersion relation - can induce precipitation of trapped Van Allen particles and have a role in the chemistry of some atmospheric components (mainly NOx). Moreover, it has also been suggested that the increase of the number of anomalous whistlers (i.e. whistlers with high value of dispersion constant) could be induced by disturbances in the Earth-ionosphere wave-guide, generated by seismo-electromagnetic emissions. On satellite, the recognition of whistlers asks for analyzing high-resolution spectrograms that cannot be downloaded to Earth, due to the limits of data transmission. For this reason, a real time identification and classification must be performed on satellite, by avoiding downloading all the unprocessed data. The procedure that we have developed is based on a Time Delay Neural Network (TDNN). The TDNN, proposed some years ago for speech recognition, can be fruitfully also applied in real-time analysis of electromagnetic spectrograms in order to detect phenomena characterized by a specific shape/signature such as those of the whistler waves. Some studies have been performed by the RNF experiment on board of the DEMETER satellite and our algorithm could be adopted on board of the satellite CSES (China Seismo-Electromagnetic Satellite), launch scheduled by the end of 2016. Moreover, the procedure can be also adopted to automatic analysis of whistlers detected on ground.

  8. The design and networking of dynamic satellite constellations for global mobile communication systems

    Science.gov (United States)

    Cullen, Cionaith J.; Benedicto, Xavier; Tafazolli, Rahim; Evans, Barry

    1993-01-01

    Various design factors for mobile satellite systems, whose aim is to provide worldwide voice and data communications to users with hand-held terminals, are examined. Two network segments are identified - the ground segment (GS) and the space segment (SS) - and are seen to be highly dependent on each other. The overall architecture must therefore be adapted to both of these segments, rather than each being optimized according to its own criteria. Terrestrial networks are grouped and called the terrestrial segment (TS). In the SS, of fundamental importance is the constellation altitude. The effect of the altitude on decisions such as constellation design choice and on network aspects like call handover statistics are fundamental. Orbit resonance is introduced and referred to throughout. It is specifically examined for its useful properties relating to GS/SS connectivities.

  9. Proactive TCP mechanism to improve Handover performance in Mobile Satellite and Terrestrial Networks

    CERN Document Server

    Vinayakray-Jani, Preetida

    2012-01-01

    Emerging standardization of Geo Mobile Radio (GMR-1) for satellite system is having strong resemblance to terrestrial GSM (Global System for Mobile communications) at the upper protocol layers and TCP (Transmission Control Protocol) is one of them. This space segment technology as well as terrestrial technology, is characterized by periodic variations in communication properties and coverage causing the termination of ongoing call as connections of Mobile Nodes (MN) alter stochastically. Although provisions are made to provide efficient communication infrastructure this hybrid space and terrestrial networks must ensure the end-to-end network performance so that MN can move seamlessly among these networks. However from connectivity point of view current TCP performance has not been engineered for mobility events in multi-radio MN. Traditionally, TCP has applied a set of congestion control algorithms (slow-start, congestion avoidance, fast retransmit, fast recovery) to probe the currently available bandwidth on...

  10. Comparison of thromboplastins using the ISI and INR system.

    Science.gov (United States)

    Moriarty, H T; Lam-Po-Tang, P R; Anastas, N

    1990-04-01

    Twelve thromboplastins were tested against a secondary reference thromboplastin (human brain CRM BCR No. 147) or a tertiary house standard (human brain thromboplastin) with plasmas from normal healthy individuals and patients on oral anticoagulant therapy. The relationship between the prothrombin ratios of the thromboplastins tested versus the reference reagent was either a straight or curved line. The International Sensitivity Index (ISI) was estimated for each of the test thromboplastins and these ranged from 0.98 to 2.24. Some ISIs stated by manufacturers were different from our results. Thromboplastins with a high ISI showed a loss of sensitivity in assessing the level of anticoagulation at the upper end of the therapeutic range. In addition, the 95% Confidence Interval (CI) of the ISI estimations were widest for thromboplastins with the highest ISIs. Conversion of the prothrombin ratio to International Normalized Ratio (INR) was most accurate with the Australasian Reference Thromboplastin (ART) and least accurate with reagents having an ISI of 2.00 and over. Thromboplastins with an ISI between 1.10 and 1.50 may be adequate for the control of oral anticoagulant therapy, but were less accurate than a thromboplastin with an ISI approximating 1.00. Factors other than ISI should be considered in the choice of a thromboplastin, in particular a measurement of the accuracy of the ISI estimation such as the 95% confidence interval estimation used here.

  11. A small satellite design for deep space network testing and training

    Science.gov (United States)

    Mcwilliams, Dennis; Slatton, Clint; Norman, Cassidy; Araiza, Joe; Jones, Jason; Tedesco, Mark; Wortman, Michael; Opiela, John; Lett, Pat; Clavenna, Michael

    1993-01-01

    With the continuing exploration of the Solar System and the reemphasis on Earth focused missions, the need for faster data transmission rates has grown. Ka-band could allow a higher data delivery rate over the current X-band, however the adverse effects of the Earth's atmosphere on Ka are as yet unknown. The Deep Space Network and Jet Propulsion Lab have proposed to launch a small satellite that would simultaneously transmit X and Ka signals to test the viability of switching to Ka-band. The Mockingbird Design Team at the University of Texas at Austin applied small satellite design principles to achieve this objective. The Mockingbird design, named BATSAT, incorporates simple, low-cost systems designed for university production and testing. The BATSAT satellite is a 0.64 m diameter, spherical panel led satellite, mounted with solar cells and omni-directional antennae. The antennae configuration negates the need for active attitude control or spin stabilization. The space-frame truss structure was designed for 11 g launch loads while allowing for easy construction and solar-panel mounting. The communication system transmits at 1 mW by carrying the required Ka and X-band transmitters, as well as an S band transmitter used for DSN training. The power system provides the 8.6 W maximum power requirements via silicon solar arrays and nickel-cadmium batteries. The BATSAT satellite will be lofted into an 1163 km, 70 deg orbit by the Pegasus launch system. This orbit fulfills DSN dish slew rate requirements while keeping the satellite out of the heaviest regions of the Van Allen radiation belts. Each of the three DSN stations capable of receiving Ka-band (Goldstone, Canberra, and Madrid) will have an average of 85 minutes of view-time per day over the satellites ten year design life. Mockingbird Designs hopes that its small satellite design will not only be applicable to this specific mission scenario, but that it could easily be modified for instrument capability for

  12. Monitoring Animal Behaviour and Environmental Interactions Using Wireless Sensor Networks, GPS Collars and Satellite Remote Sensing

    Directory of Open Access Journals (Sweden)

    Peter Corke

    2009-05-01

    Full Text Available Remote monitoring of animal behaviour in the environment can assist in managing both the animal and its environmental impact. GPS collars which record animal locations with high temporal frequency allow researchers to monitor both animal behaviour and interactions with the environment. These ground-based sensors can be combined with remotely-sensed satellite images to understand animal-landscape interactions. The key to combining these technologies is communication methods such as wireless sensor networks (WSNs. We explore this concept using a case-study from an extensive cattle enterprise in northern Australia and demonstrate the potential for combining GPS collars and satellite images in a WSN to monitor behavioural preferences and social behaviour of cattle.

  13. Networks systems and operations. [wideband communication techniques for data links with satellites

    Science.gov (United States)

    1975-01-01

    The application of wideband communication techniques for data links with satellites is discussed. A diagram of the demand assigned voice communications system is provided. The development of prototype integrated spacecraft paramps at S- and C-bands is described and the performance of space-qualified paramps is tabulated. The characteristics of a dual parabolic cylinder monopulse zoom antenna for use with the tracking and data relay satellite system (TDRSS) are analyzed. The development of a universally applicable transponder at S-band is reported. A block diagram of the major subassemblies of the S-band transponder is included. The technology aspects of network timing and synchronization of communication systems are to show the use of the Omega navigation system. The telemetry data compression system used during the Skylab program is evaluated.

  14. The ISIS pre-injector reconfiguration

    Energy Technology Data Exchange (ETDEWEB)

    Wood, T., E-mail: trevor.wood@stfc.ac.uk; Faircloth, D. C.; Lawrie, S. R.; Letchford, A. P.; Whitehead, M. O.; Pike, T.; Perkins, M. [ISIS Pulsed Spallation Neutron and Muon Facility, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Oxfordshire (United Kingdom)

    2016-02-15

    With the introduction of a new “low energy beams” group at ISIS, the decision was taken to expand the ion source area. This paper will explain what actions were taken, how this has improved the present working environment and how the space will be used to accommodate a medium energy beam transport (MEBT) section after the existing radio-frequency quadrupole. The MEBT will incorporate three 202.5 MHz re-bunching cavities and will achieve a transmission of 96% with minimal emittance growth.

  15. Magnetic resonance imaging research in sub-Saharan Africa: challenges and satellite-based networking implementation.

    Science.gov (United States)

    Latourette, Matthew T; Siebert, James E; Barto, Robert J; Marable, Kenneth L; Muyepa, Anthony; Hammond, Colleen A; Potchen, Michael J; Kampondeni, Samuel D; Taylor, Terrie E

    2011-08-01

    As part of an NIH-funded study of malaria pathogenesis, a magnetic resonance (MR) imaging research facility was established in Blantyre, Malaŵi to enhance the clinical characterization of pediatric patients with cerebral malaria through application of neurological MR methods. The research program requires daily transmission of MR studies to Michigan State University (MSU) for clinical research interpretation and quantitative post-processing. An intercontinental satellite-based network was implemented for transmission of MR image data in Digital Imaging and Communications in Medicine (DICOM) format, research data collection, project communications, and remote systems administration. Satellite Internet service costs limited the bandwidth to symmetrical 384 kbit/s. DICOM routers deployed at both the Malaŵi MRI facility and MSU manage the end-to-end encrypted compressed data transmission. Network performance between DICOM routers was measured while transmitting both mixed clinical MR studies and synthetic studies. Effective network latency averaged 715 ms. Within a mix of clinical MR studies, the average transmission time for a 256 × 256 image was ~2.25 and ~6.25 s for a 512 × 512 image. Using synthetic studies of 1,000 duplicate images, the interquartile range for 256 × 256 images was [2.30, 2.36] s and [5.94, 6.05] s for 512 × 512 images. Transmission of clinical MRI studies between the DICOM routers averaged 9.35 images per minute, representing an effective channel utilization of ~137% of the 384-kbit/s satellite service as computed using uncompressed image file sizes (including the effects of image compression, protocol overhead, channel latency, etc.). Power unreliability was the primary cause of interrupted operations in the first year, including an outage exceeding 10 days.

  16. Trans-Pacific HDR Satellite Communications Experiment Phase-2 Project Plan and Experimental Network

    Science.gov (United States)

    Hsu, Eddie; Kadowaki, Naoto; Yoshimura, Naoko; Takahashi, Takashi; Yoshikawa, Makoto; Bergman, Larry; Bhasin, Kul

    2000-01-01

    The trans-Pacific high data rate (TP-HDR) satellite communications experiment was proposed at the Japan-U.S. Cooperation in Space (JUCS) Program Workshop held in Hawaii in 1993 and remote high definition video post-production was demonstrated as the first phase trial. ATM-based 45 Mbps trans-Pacific link was established in the first phase, and the following experiments with 155 Mbps was planned as the phase 2. This paper describes the experimental network configuration and project plan of TP-HDR experiment phase 2. Additional information is provided in the original.

  17. Fast Road Network Extraction in Satellite Images Using Mathematical Morphology and Markov Random Fields

    Directory of Open Access Journals (Sweden)

    Thierry Géraud

    2004-12-01

    Full Text Available We present a fast method for road network extraction in satellite images. It can be seen as a transposition of the segmentation scheme “watershed transform + region adjacency graph + Markov random fields” to the extraction of curvilinear objects. Many road extractors which are composed of two stages can be found in the literature. The first one acts like a filter that can decide from a local analysis, at every image point, if there is a road or not. The second stage aims at obtaining the road network structure. In the method we propose to rely on a “potential” image, that is, unstructured image data that can be derived from any road extractor filter. In such a potential image, the value assigned to a point is a measure of its likelihood to be located in the middle of a road. A filtering step applied on the potential image relies on the area closing operator followed by the watershed transform to obtain a connected line which encloses the road network. Then a graph describing adjacency relationships between watershed lines is built. Defining Markov random fields upon this graph, associated with an energetic model of road networks, leads to the expression of road network extraction as a global energy minimization problem. This method can easily be adapted to other image processing fields, where the recognition of curvilinear structures is involved.

  18. Comparision of Clustering Algorithms usingNeural Network Classifier for Satellite Image Classification

    Directory of Open Access Journals (Sweden)

    S.Praveena

    2015-06-01

    Full Text Available This paper presents a hybrid clustering algorithm and feed-forward neural network classifier for land-cover mapping of trees, shade, building and road. It starts with the single step preprocessing procedure to make the image suitable for segmentation. The pre-processed image is segmented using the hybrid genetic-Artificial Bee Colony(ABC algorithm that is developed by hybridizing the ABC and FCM to obtain the effective segmentation in satellite image and classified using neural network . The performance of the proposed hybrid algorithm is compared with the algorithms like, k-means, Fuzzy C means(FCM, Moving K-means, Artificial Bee Colony(ABC algorithm, ABC-GA algorithm, Moving KFCM and KFCM algorithm.

  19. Cost Analysis of Algorithm Based Billboard Manger Based Handover Method in LEO satellite Networks

    Directory of Open Access Journals (Sweden)

    Suman Kumar Sikdar

    2012-12-01

    Full Text Available Now-a-days LEO satellites have an important role in global communication system. They have some advantages like low power requirement and low end-to-end delay, more efficient frequency spectrum utilization between satellites and spot beams over GEO and MEO. So in future they can be used as a replacement of modern terrestrial wireless networks. But the handover occurrence is more due to the speed of the LEOs. Different protocol has been proposed for a successful handover among which BMBHO is more efficient. But it had a problem during the selection of the mobile node during handover. In our previous work we have proposed an algorithm so that the connection can be established easily with the appropriate satellite. In this paper we will evaluate the mobility management cost of Algorithm based Billboard Manager Based Handover method (BMBHO. A simulation result shows that the cost is lower than the cost of Mobile IP of SeaHO-LEO and PatHOLEO

  20. Modelling and observation of transionospheric propagation results from ISIS II in preparation for ePOP

    Directory of Open Access Journals (Sweden)

    R. G. Gillies

    2007-02-01

    Full Text Available The enhanced Polar Outflow Probe (ePOP is scheduled to be launched as part of the Cascade Demonstrator Small-Sat and Ionospheric Polar Explorer (CASSIOPE satellite in early 2008. A Radio Receiver Instrument (RRI on ePOP will receive HF transmissions from various ground-based transmitters. In preparation for the ePOP mission, data from a similar transionospheric experiment performed by the International Satellites for Ionospheric Studies (ISIS II satellite has been studied. Prominent features in the received 9.303-MHz signal were periodic Faraday fading of signal intensity at rates up to 13 Hz and a time of arrival delay between the O- and X-modes of up to 0.8 ms. Both features occurred when the satellite was above or south of the Ottawa transmitter. Ionospheric models for ray tracing were constructed using both International Reference Ionosphere (IRI profiles and local peak electron density values from ISIS ionograms. Values for fade rate and differential mode delay were computed and compared to the values observed in the ISIS II data. The computed values showed very good agreement to the observed values of both received signal parameters when the topside sounding foF2 values were used to scale IRI profiles, but not when strictly modelled IRI profiles were used. It was determined that the primary modifier of the received signal parameters was the foF2 density and not the shape of the profile. This dependence was due to refraction, at the 9.303-MHz signal frequency, causing the rays to travel larger distances near the peak density where essentially all the mode splitting occurred. This study should assist in interpretation of ePOP RRI data when they are available.

  1. Minimum Number of Observation Points for LEO Satellite Orbit Estimation by OWL Network

    Science.gov (United States)

    Park, Maru; Jo, Jung Hyun; Cho, Sungki; Choi, Jin; Kim, Chun-Hwey; Park, Jang-Hyun; Yim, Hong-Suh; Choi, Young-Jun; Moon, Hong-Kyu; Bae, Young-Ho; Park, Sun-Youp; Kim, Ji-Hye; Roh, Dong-Goo; Jang, Hyun-Jung; Park, Young-Sik; Jeong, Min-Ji

    2015-12-01

    By using the Optical Wide-field Patrol (OWL) network developed by the Korea Astronomy and Space Science Institute (KASI) we generated the right ascension and declination angle data from optical observation of Low Earth Orbit (LEO) satellites. We performed an analysis to verify the optimum number of observations needed per arc for successful estimation of orbit. The currently functioning OWL observatories are located in Daejeon (South Korea), Songino (Mongolia), and Oukaïmeden (Morocco). The Daejeon Observatory is functioning as a test bed. In this study, the observed targets were Gravity Probe B, COSMOS 1455, COSMOS 1726, COSMOS 2428, SEASAT 1, ATV-5, and CryoSat-2 (all in LEO). These satellites were observed from the test bed and the Songino Observatory of the OWL network during 21 nights in 2014 and 2015. After we estimated the orbit from systematically selected sets of observation points (20, 50, 100, and 150) for each pass, we compared the difference between the orbit estimates for each case, and the Two Line Element set (TLE) from the Joint Space Operation Center (JSpOC). Then, we determined the average of the difference and selected the optimal observation points by comparing the average values.

  2. An Optical Sensor Network for Vegetation Phenology Monitoring and Satellite Data Calibration

    Directory of Open Access Journals (Sweden)

    Michal Heliasz

    2011-08-01

    Full Text Available We present a network of sites across Fennoscandia for optical sampling of vegetation properties relevant for phenology monitoring and satellite data calibration. The network currently consists of five sites, distributed along an N-S gradient through Sweden and Finland. Two sites are located in coniferous forests, one in a deciduous forest, and two on peatland. The instrumentation consists of dual-beam sensors measuring incoming and reflected red, green, NIR, and PAR fluxes at 10-min intervals, year-round. The sensors are mounted on separate masts or in flux towers in order to capture radiation reflected from within the flux footprint of current eddy covariance measurements. Our computations and model simulations demonstrate the validity of using off-nadir sampling, and we show the results from the first year of measurement. NDVI is computed and compared to that of the MODIS instrument on-board Aqua and Terra satellite platforms. PAR fluxes are partitioned into reflected and absorbed components for the ground and canopy. The measurements demonstrate that the instrumentation provides detailed information about the vegetation phenology and variations in reflectance due to snow cover variations and vegetation development. Valuable information about PAR absorption of ground and canopy is obtained that may be linked to vegetation productivity.

  3. An optical sensor network for vegetation phenology monitoring and satellite data calibration.

    Science.gov (United States)

    Eklundh, Lars; Jin, Hongxiao; Schubert, Per; Guzinski, Radoslaw; Heliasz, Michal

    2011-01-01

    We present a network of sites across Fennoscandia for optical sampling of vegetation properties relevant for phenology monitoring and satellite data calibration. The network currently consists of five sites, distributed along an N-S gradient through Sweden and Finland. Two sites are located in coniferous forests, one in a deciduous forest, and two on peatland. The instrumentation consists of dual-beam sensors measuring incoming and reflected red, green, NIR, and PAR fluxes at 10-min intervals, year-round. The sensors are mounted on separate masts or in flux towers in order to capture radiation reflected from within the flux footprint of current eddy covariance measurements. Our computations and model simulations demonstrate the validity of using off-nadir sampling, and we show the results from the first year of measurement. NDVI is computed and compared to that of the MODIS instrument on-board Aqua and Terra satellite platforms. PAR fluxes are partitioned into reflected and absorbed components for the ground and canopy. The measurements demonstrate that the instrumentation provides detailed information about the vegetation phenology and variations in reflectance due to snow cover variations and vegetation development. Valuable information about PAR absorption of ground and canopy is obtained that may be linked to vegetation productivity.

  4. Modulation Classification of Satellite Communication Signals Using Cumulants and Neural Networks

    Science.gov (United States)

    Smith, Aaron; Evans, Michael; Downey, Joseph

    2017-01-01

    National Aeronautics and Space Administration (NASA)'s future communication architecture is evaluating cognitive technologies and increased system intelligence. These technologies are expected to reduce the operational complexity of the network, increase science data return, and reduce interference to self and others. In order to increase situational awareness, signal classification algorithms could be applied to identify users and distinguish sources of interference. A significant amount of previous work has been done in the area of automatic signal classification for military and commercial applications. As a preliminary step, we seek to develop a system with the ability to discern signals typically encountered in satellite communication. Proposed is an automatic modulation classifier which utilizes higher order statistics (cumulants) and an estimate of the signal-to-noise ratio. These features are extracted from baseband symbols and then processed by a neural network for classification. The modulation types considered are phase-shift keying (PSK), amplitude and phase-shift keying (APSK),and quadrature amplitude modulation (QAM). Physical layer properties specific to the Digital Video Broadcasting - Satellite- Second Generation (DVB-S2) standard, such as pilots and variable ring ratios, are also considered. This paper will provide simulation results of a candidate modulation classifier, and performance will be evaluated over a range of signal-to-noise ratios, frequency offsets, and nonlinear amplifier distortions.

  5. A system for the simulation and evaluation of satellite communication networks

    Science.gov (United States)

    Bagwell, J. W.

    1984-01-01

    With the emergence of a new era in satellite communications, brought about by NASA's thrust into the Ka band with multibeam and onboard processing technologies, new and innovative techniques for evaluating these concepts and systems are required. To this end, NASA, in conjunction with its extensive program for advanced communications technology development, has undertaken to develop a concept for the simulation and evaluation of a complete communications network. Incorporated in this network will be proof-of-concept models of the latest technologies proposed for future satellite communications systems. These include low noise receivers, matrix switches, baseband processors, and solid state and tube type high power amplifiers. To accomplish this, numerous supporting technologies must be added to those aforementioned proof-of-concept models. These include controllers for synchronization, order wire, resource allocation, gain compensation, signal leveling, power augmentation, and rain fade and range delay simulation. Taken together, these will be assembled to comprise a system capable of addressing numerous design and performance questions. The simulation and evaluation system, as planned, will be modular in design and implementation, capable of modification and updating to track and evaluate a continuum of emerging concepts and technologies. Previously announced in STAR as N84-13400

  6. Quantum communication for satellite-to-ground networks with partially entangled states

    Science.gov (United States)

    Chen, Na; Quan, Dong-Xiao; Pei, Chang-Xing; Yang-Hong

    2015-02-01

    To realize practical wide-area quantum communication, a satellite-to-ground network with partially entangled states is developed in this paper. For efficiency and security reasons, the existing method of quantum communication in distributed wireless quantum networks with partially entangled states cannot be applied directly to the proposed quantum network. Based on this point, an efficient and secure quantum communication scheme with partially entangled states is presented. In our scheme, the source node performs teleportation only after an end-to-end entangled state has been established by entanglement swapping with partially entangled states. Thus, the security of quantum communication is guaranteed. The destination node recovers the transmitted quantum bit with the help of an auxiliary quantum bit and specially defined unitary matrices. Detailed calculations and simulation analyses show that the probability of successfully transferring a quantum bit in the presented scheme is high. In addition, the auxiliary quantum bit provides a heralded mechanism for successful communication. Based on the critical components that are presented in this article an efficient, secure, and practical wide-area quantum communication can be achieved. Project supported by the National Natural Science Foundation of China (Grant Nos. 61072067 and 61372076), the 111 Project (Grant No. B08038), the Fund from the State Key Laboratory of Integrated Services Networks (Grant No. ISN 1001004), and the Fundamental Research Funds for the Central Universities (Grant Nos. K5051301059 and K5051201021).

  7. The Goodness of Simultaneous Fits in ISIS

    CERN Document Server

    Kühnel, Matthias; Grossberger, Christoph; Ballhausen, Ralf; Dauser, Thomas; Schwarm, Fritz-Walter; Kreykenbohm, Ingo; Nowak, Michael A; Pottschmidt, Katja; Ferrigno, Carlo; Rothschild, Richard E; Martínez-Núñez, Silvia; Torrejón, José Miguel; Fürst, Felix; Klochkov, Dmitry; Staubert, Rüdiger; Kretschmar, Peter; Wilms, Jörn

    2016-01-01

    In a previous work, we introduced a tool for analyzing multiple datasets simultaneously, which has been implemented into ISIS. This tool was used to fit many spectra of X-ray binaries. However, the large number of degrees of freedom and individual datasets raise an issue about a good measure for a simultaneous fit quality. We present three ways to check the goodness of these fits: we investigate the goodness of each fit in all datasets, we define a combined goodness exploiting the logical structure of a simultaneous fit, and we stack the fit residuals of all datasets to detect weak features. These tools are applied to all RXTE-spectra from GRO 1008-57, revealing calibration features that are not detected significantly in any single spectrum. Stacking the residuals from the best-fit model for the Vela X-1 and XTE J1859+083 data evidences fluorescent emission lines that would have gone undetected otherwise.

  8. THE GOODNESS OF SIMULTANEOUS FITS IN ISIS

    Directory of Open Access Journals (Sweden)

    Matthias Kühnel

    2016-02-01

    Full Text Available In a previous work, we introduced a tool for analyzing multiple datasets simultaneously, which has been implemented into ISIS. This tool was used to fit many spectra of X-ray binaries. However, the large number of degrees of freedom and individual datasets raise an issue about a good measure for a simultaneous fit quality. We present three ways to check the goodness of these fits: we investigate the goodness of each fit in all datasets, we define a combined goodness exploiting the logical structure of a simultaneous fit, and we stack the fit residuals of all datasets to detect weak features. These tools are applied to all RXTE-spectra from GRO 1008−57, revealing calibration features that are not detected significantly in any single spectrum. Stacking the residuals from the best-fit model for the Vela X-1 and XTE J1859+083 data evidences fluorescent emission lines that would have gone undetected otherwise.

  9. Resilient Sensor Networks with Spatiotemporal Interpolation of Missing Sensors: An Example of Space Weather Forecasting by Multiple Satellites.

    Science.gov (United States)

    Tokumitsu, Masahiro; Hasegawa, Keisuke; Ishida, Yoshiteru

    2016-04-15

    This paper attempts to construct a resilient sensor network model with an example of space weather forecasting. The proposed model is based on a dynamic relational network. Space weather forecasting is vital for a satellite operation because an operational team needs to make a decision for providing its satellite service. The proposed model is resilient to failures of sensors or missing data due to the satellite operation. In the proposed model, the missing data of a sensor is interpolated by other sensors associated. This paper demonstrates two examples of space weather forecasting that involves the missing observations in some test cases. In these examples, the sensor network for space weather forecasting continues a diagnosis by replacing faulted sensors with virtual ones. The demonstrations showed that the proposed model is resilient against sensor failures due to suspension of hardware failures or technical reasons.

  10. The status of ISI in the UK nuclear industry

    Energy Technology Data Exchange (ETDEWEB)

    Bann, T.; Rogerson, A. [AEA Technology, Risley (United Kingdom). Nuclear NDE Services

    1999-08-01

    This paper reviews the status of in-service inspection (ISI) in UK nuclear power generation industry through the experience of its nuclear utilities. The paper is intended to be a summary of some of the most recent and relevant ISI issues facing the utilities and the solutions devised to address those issues. (orig.)

  11. Core-based Shared Tree Multicast Routing Algorithms for LEO Satellite IP Networks

    Institute of Scientific and Technical Information of China (English)

    Cheng Lianzhen; Zhang Jun; Liu Kai

    2007-01-01

    A new core-based shared tree algorithm, viz core-cluster combination-based shared tree (CCST) algorithm and the weighted version (i.e. w-CCST algorithm) are proposed in order to resolve the channel resources waste problem in typical source-based multicast routing algorithms in low earth orbit (LEO) satellite IP networks. The CCST algorithm includes the dynamic approximate center (DAC)core selection method and the core-cluster combination multicast route construction scheme. Without complicated onboard computation,the DAC method is uniquely developed for highly dynamic networks of periodical and regular movement. The core-cluster combination method takes core node as the initial core-cluster, and expands it stepwise to construct an entire multicast tree at the lowest tree cost by a shortest path scheme between the newly-generated core-cluster and surplus group members, which results in great bandwidth utilization.Moreover, the w-CCST algorithm is able to strike a balance between performance of tree cost and that of end-to-end propagation delay by adjusting the weighted factor to meet strict end-to-end delay requirements of some real-time multicast services at the expense of a slight increase in tree cost. Finally, performance comparison is conducted between the proposed algorithms and typical algorithms in LEO satellite IP networks. Simulation results show that the CCST algorithm significantly decreases the average tree cost against to the others, and also the average end-to-end propagation delay of w-CCST algorithm is lower than that of the CCST algorithm.

  12. On Successive Refinement of Diversity for Fading ISI Channels

    CERN Document Server

    Dusad, S

    2007-01-01

    Rate and diversity impose a fundamental tradeoff in communications. This tradeoff was investigated for Intersymbol Interference (ISI) channels in [4]. A different point of view was explored in [1] where high-rate codes were designed so that they have a high-diversity code embedded within them. Such diversity embedded codes were investigated for flat fading channels and in this paper we explore its application to ISI channels. In particular, we investigate the rate tuples achievable for diversity embedded codes for scalar ISI channels through particular coding strategies. The main result of this paper is that the diversity multiplexing tradeoff for fading ISI channels is indeed successively refinable. This implies that for fading single input single output (SISO) ISI channels one can embed a high diversity code within a high rate code without any performance loss (asymptotically). This is related to a deterministic structural observation about the asymptotic behavior of frequency response of channel with respe...

  13. A New Damage Assessment Method by Means of Neural Network and Multi-Sensor Satellite Data

    Directory of Open Access Journals (Sweden)

    Alessandro Piscini

    2017-08-01

    Full Text Available Artificial Neural Network (ANN is a valuable and well-established inversion technique for the estimation of geophysical parameters from satellite images. After training, ANNs are able to generate very fast products for several types of applications. Satellite remote sensing is an efficient way to detect and map strong earthquake damage for contributing to post-disaster activities during emergency phases. This work aims at presenting an application of the ANN inversion technique addressed to the evaluation of building collapse ratio (CR, defined as the number of collapsed buildings with respect to the total number of buildings in a city block, by employing optical and SAR satellite data. This is done in order to directly relate changes in images with damage that has occurred during strong earthquakes. Furthermore, once they have been trained, neural networks can be used rapidly at application stage. The goal was to obtain a general tool suitable for re-use in different scenarios. An ANN has been implemented in order to emulate a regression model and to estimate the CR as a continuous function. The adopted ANN has been trained using some features obtained from optical and Synthetic Aperture Radar (SAR images, as inputs, and the corresponding values of collapse ratio obtained from the survey of the 2010 M7 Haiti Earthquake, i.e., as target output. As regards the optical data, we selected three change parameters: the Normalized Difference Index (NDI, the Kullback–Leibler divergence (KLD, and Mutual Information (MI. Concerning the SAR images, the Intensity Correlation Difference (ICD and the KLD parameters have been considered. Exploiting an object-oriented approach, a segmentation of the study area into several regions has been performed. In particular, damage maps have been generated by considering a set of polygons (in which satellite parameters have been calculated extracted from the open source Open Street Map (OSM geo-database. The trained

  14. Neural Network Change Detection Model for Satellite Images Using Textural and Spectral Characteristics

    Directory of Open Access Journals (Sweden)

    A. K. Helmy

    2010-01-01

    Full Text Available Problem statement: Change detection is the process of identifying difference of the state of an object or phenomena by observing it at different time. Essentially, it involves the ability to quantify temporal effects using multi-temporal data sets. Information about change is necessary for evaluating land cover and the management of natural resources. Approach: A neural network model based on both spectral and textural analysis is developed. Change detection system in this study is presented using modified version of back-propagation-training algorithm with dynamic learning rate and momentum. Through proposed model, the two images at different dates are fed into the input layer of neural network, in addition with Variance, Skewness and Eculedian for each image that represent different texture measure. This leads to better discrimination process. Results: The results showed that the trained network with texture measures achieve 23% higher accuracy than that without textural parameters. Conclusion: Adding textural parameters of satellite images through training phase increases the efficiently of change detection process also, it provides adequate information about the type of changes. It also found, when using dynamic momentum and learning rate, time and effort needed to select their appropriate value is reduced.

  15. A FD/DAMA network architecture for the first generation land mobile satellite services

    Science.gov (United States)

    Yan, T.-Y.; Wang, C.; Cheng, U.; Dessouky, K.; Rafferty, W.

    1989-01-01

    A frequency division/demand assigned multiple access (FD/DAMA) network architecture for the first-generation land mobile satellite services is presented. Rationales and technical approaches are described. In this architecture, each mobile subscriber must follow a channel access protocol to make a service request to the network management center before transmission for either open-end or closed-end services. Open-end service requests will be processed on a blocked call cleared basis, while closed-end requests will be processed on a first-come-first-served basis. Two channel access protocols are investigated, namely, a recently proposed multiple channel collision resolution scheme which provides a significantly higher useful throughput, and the traditional slotted Aloha scheme. The number of channels allocated for either open-end or closed-end services can be adaptively changed according to aggregated traffic requests. Both theoretical and simulation results are presented. Theoretical results have been verified by simulation on the JPL network testbed.

  16. Quantum communication for satellite-to-ground networks with partially entangled states

    Institute of Scientific and Technical Information of China (English)

    陈娜; 权东晓; 裴昌幸; 杨宏

    2015-01-01

    To realize practical wide-area quantum communication, a satellite-to-ground network with partially entangled states is developed in this paper. For efficiency and security reasons, the existing method of quantum communication in distributed wireless quantum networks with partially entangled states cannot be applied directly to the proposed quantum network. Based on this point, an efficient and secure quantum communication scheme with partially entangled states is presented. In our scheme, the source node performs teleportation only after an end-to-end entangled state has been established by entanglement swapping with partially entangled states. Thus, security of quantum communication is guaranteed. The destination node recovers the transmitted quantum bit with the help of auxiliary quantum bit and specially defined unitary matrices. Detailed calculations and simulation analyses show that in the presented scheme, the probability of successfully transferring a quantum bit is high. In addition, the auxiliary quantum bit provides a heralded mechanism for successful communication. Based on these critical components presented in this article, an efficient, secure, and practical wide-area quantum communication can be achieved.

  17. Journal maps on the basis of Scopus data: a comparison with the Journal Citation Reports of the ISI

    NARCIS (Netherlands)

    Leydesdorff, L.; de Moya-Anegon, F.; Guerrero-Bote, V.P.

    2010-01-01

    Using the Scopus dataset (1996-2007) a grand matrix of aggregated journal-journal citations was constructed. This matrix can be compared in terms of the network structures with the matrix contained in the Journal Citation Reports (JCR) of the Institute of Scientific Information (ISI). Because the Sc

  18. Journal maps on the basis of Scopus data: a comparison with the Journal Citation Reports of the ISI

    NARCIS (Netherlands)

    Leydesdorff, L.; de Moya-Anegon, F.; Guerrero-Bote, V.P.

    2010-01-01

    Using the Scopus dataset (1996-2007) a grand matrix of aggregated journal-journal citations was constructed. This matrix can be compared in terms of the network structures with the matrix contained in the Journal Citation Reports (JCR) of the Institute of Scientific Information (ISI). Because the

  19. Unlicensed Spectrum Sharing Game Between LEO Satellites and Terrestrial Cognitive Radio Networks

    Institute of Scientific and Technical Information of China (English)

    XIE Zhuochen; MA Lu; LIANG Xuwen

    2012-01-01

    By cognitive radio,the low Earth orbit (LEO) satellites may prefer to operate in the unlicensed spectrum which is open to all the users,and compete for the limited resources with terrestrial cognitive radio networks (CRNs).The competition can be regarded as a game and analyzed with game theory.This particular unlicensed spectrum sharing problem is modeled here,and the special properties of “spatially-distinguished-interference” and the short period of the interactions between satellites and terrestrial CRNs are explored.Then,the problem is formulated as a “partially-blind” finitely repeated prisoner's dilemma by game theory.Finally,we begin with two promising spectrum sharing schemes,which can be used to enforce the frequency reuse among the remotely located terrestrial CRN players as well as to overcome the observation noise.By analysis and comparison,it is proposed that the novel refreshing-contrite-tit-for-tat (R-CTFT) is the optimal spectrum sharing scheme.Simulation results verify that it can be used to utilize the spectrum most efficiently.

  20. A Topology Control Strategy with Reliability Assurance for Satellite Cluster Networks in Earth Observation

    Science.gov (United States)

    Chen, Qing; Zhang, Jinxiu; Hu, Ze

    2017-01-01

    This article investigates the dynamic topology control problem of satellite cluster networks (SCNs) in Earth observation (EO) missions by applying a novel metric of stability for inter-satellite links (ISLs). The properties of the periodicity and predictability of satellites’ relative position are involved in the link cost metric which is to give a selection criterion for choosing the most reliable data routing paths. Also, a cooperative work model with reliability is proposed for the situation of emergency EO missions. Based on the link cost metric and the proposed reliability model, a reliability assurance topology control algorithm and its corresponding dynamic topology control (RAT) strategy are established to maximize the stability of data transmission in the SCNs. The SCNs scenario is tested through some numeric simulations of the topology stability of average topology lifetime and average packet loss rate. Simulation results show that the proposed reliable strategy applied in SCNs significantly improves the data transmission performance and prolongs the average topology lifetime. PMID:28241474

  1. Adaptive Predistortions Based on Neural Networks Associated with Levenberg-Marquardt Algorithm for Satellite Down Links

    Directory of Open Access Journals (Sweden)

    Roviras Daniel

    2008-01-01

    Full Text Available Abstract This paper presents adaptive predistortion techniques based on a feed-forward neural network (NN to linearize power amplifiers such as those used in satellite communications. Indeed, it presents the suitable NN structures which give the best performances for three satellite down links. The first link is a stationary memoryless travelling wave tube amplifier (TWTA, the second one is a nonstationary memoryless TWT amplifier while the third is an amplifier with memory modeled by a memoryless amplifier followed by a linear filter. Equally important, it puts forward the studies concerning the application of different NN training algorithms in order to determine the most prefermant for adaptive predistortions. This comparison examined through computer simulation for 64 carriers and 16-QAM OFDM system, with a Saleh's TWT amplifier, is based on some quality measure (mean square error, the required training time to reach a particular quality level, and computation complexity. The chosen adaptive predistortions (NN structures associated with an adaptive algorithm have a low complexity, fast convergence, and best performance.

  2. Development of Cooperative Communication Techniques for a Network of Small Satellites and Cubesats in Deep Space

    Science.gov (United States)

    Babuscia, Alessandra; Cheung, Kar-Ming; Divsalar, Dariush; Lee, Charles

    2014-01-01

    This paper aims to address this problem by proposing cooperative communication approaches in which multiple CubeSats communicate cooperatively together to improve the link performance with respect to the case of a single satellite transmitting. Three approaches are proposed: a beam-forming approach, a coding approach, and a network approach. The approaches are applied to the specific case of a proposed constellation of CubeSats at the Lunar Lagrangian point L1 which aims to perform radio astronomy at very low frequencies (30 KHz -3 MHz). The paper describes the development of the approaches, the simulation and a graphical user interface developed in Matlab which allows to perform trade-offs across multiple constellation's configurations.

  3. A novel spectral index to automatically extract road networks from WorldView-2 satellite imagery

    Directory of Open Access Journals (Sweden)

    Kaveh Shahi

    2015-06-01

    Full Text Available This research develops a spectral index to automatically extract asphalt road networks named road extraction index (REI. This index uses WorldView-2 (WV-2 imagery, which has high spatial resolution and is multispectral. To determine the best bands for WV-2, field spectral data using a field spectroradiometer were collected. These data were then analyzed statistically. The bands were selected through the methodology of stepwise discriminant analysis. The appropriate WV-2 bands were distinguished from one another as per significant wavelengths. The proposed index is based on this classification. By applying REI to WV-2 imagery, we can extract asphalt roads accurately. Results demonstrate that REI is automated, transferable, and efficient in asphalt road extraction from high-resolution satellite imagery.

  4. Assimilation of Real-Time Satellite And Human Sensor Networks for Modeling Natural Disasters

    Science.gov (United States)

    Aulov, O.; Halem, M.; Lary, D. J.

    2011-12-01

    We describe the development of underlying technologies needed to address the merging of a web of real time satellite sensor Web (SSW) and Human Sensor Web (HSW) needed to augment the US response to extreme events. As an initial prototyping step and use case scenario, we consider the development of two major system tools that can be transitioned from research to the responding operational agency for mitigating coastal oil spills. These tools consist of the capture of Situation Aware (SA) Social Media (SM) Data, and assimilation of the processed information into forecasting models to provide incident decision managers with interactive virtual spatial temporal animations superimposed with probabilistic data estimates. The system methodologies are equally applicable to the wider class of extreme events such as plume dispersions from volcanoes or massive fires, major floods, hurricane impacts, radioactive isotope dispersions from nuclear accidents, etc. A successful feasibility demonstration of this technology has been shown in the case of the Deepwater Horizon Oil Spill where Human Sensor Networks have been combined with a geophysical model to perform parameter assessments. Flickr images of beached oil were mined from the spill area, geolocated and timestamped and converted into geophysical data. This data was incorporated into General NOAA Operational Modeling Environment (GNOME), a Lagrangian forecast model that uses near real-time surface winds, ocean currents, and satellite shape profiles of oil to generate a forecast of plume movement. As a result, improved estimates of diffusive coefficients and rates of oil spill were determined. Current approaches for providing satellite derived oil distributions are collected from a satellite sensor web of operational and research sensors from many countries, and a manual analysis is performed by NESDIS. A real time SA HSW processing system based on geolocated SM data from sources such as Twitter, Flickr, YouTube etc., greatly

  5. A classification of the ISIS program using Bloom's cognitive taxonomy

    Science.gov (United States)

    Clevenstine, Richard F.

    This article focuses on the practical use of Bloom's Taxonomy of Educational Objectives. The current status of analyzing and classifying test items and behavioral objectives was examined in this study. Specifically, the purpose of this study was to analyze and classify the ISIS minicourse performance objectives and criterion-referenced test items according to Bloom's cognitive Taxonomy in order to determine what levels of cognition the ISIS instructional materials are directed. The performance objectives and test items of thirty-three ISIS minicourses and criterion-referenced tests were collected and classified. Four research questions were posed in the study. The findings indicate that ISIS minicourse test items and performance objectives are written primarily at the Knowledge and Comprehension levels. The ISIS instructional materials reflect low percentages of upper cognitive level test items and performance objectives. Based upon the use of a chi-square analysis, twenty-four of the ISIS minicourses and tests demonstrate a positive congruence between their performance objectives and criterion-referenced test items. Nine ISIS minicourses were found to demonstrate a negative relationship between their performance objectives and test items. Implications and Recommendations based on the findings of the studies are provided.

  6. Coupling of ground biosensor networks for water monitoring with satellite observations in assessing Leptospirosis

    Science.gov (United States)

    Skouloudis, A. N.; Rickerby, D. G.

    2012-12-01

    Leptospirosis became recently a major public-health problem that is closely related with the environment (Nature review Oct 2009, Vol 7, pp 736-747). This disease originates from zoonotic pathogens associated with asymptomatic rodent carriers. Unfortunately, it effects human populations via various direct and indirect routes. This disease can claim many victims with large outbreaks during natural disasters or floods occurring during seasonal conditions. The severity of the illness ranges from subclinical infection to a fulminating fatal disease. Improved water quality monitoring techniques based on biosensor, optical, micro-fluidic and information technologies are leading to radical changes in our ability to perceive and monitor the aquatic environment. Biosensors are capable of providing specific, high spatial resolution information and allow unattended operation that will be particularly useful for water borne related diseases. Current research on biosensors is leading to solutions to problems for several contaminants that were previously irresolvable due to their high degree of complexity. Networking of the sensors enables sensitive monitoring systems allowing real-time monitoring of pollutants and facilitates data transmission between the measurement points and central control stations for continuous surveillance and to provide an early warning capability. The application of intelligent biosensor networks for water quality monitoring and detection of localized sources of pollution are discussed together with the setting up of a methodology that utilizes images from satellite coupled with in-situ sensors for anticipating the zones of potential evolution of this disease and assessing the population at risk. Environmental and climatic conditions that are associated the outbreaks are described and the rational of combining earth observations coupled with advanced in-situ biosensors is explained. The implementation of sensor networks for data collection and exposure

  7. The utility of satellite fire product accuracy information - Perspectives and recommendations from the southern Africa fire network

    NARCIS (Netherlands)

    Roy, D.P.; Trigg, S.N.; Bhima, R.; Brockett, B.H.; Mutanga, O.; Virgilo, S.

    2006-01-01

    This correspondence gives Southern Africa Fire Network (SAFNet) perspectives on the utility of satellite fire product accuracy information, drawing on two main sources: insights gained during SAFNet's six years of working together, and relevant findings from a SAFNet focus group study that explored

  8. Destination directed packet switch architecture for a 30/20 GHz FDMA/TDM geostationary communication satellite network

    Science.gov (United States)

    Ivancic, William D.; Shalkhauser, Mary JO

    1991-01-01

    Emphasis is on a destination directed packet switching architecture for a 30/20 GHz frequency division multiplex access/time division multiplex (FDMA/TDM) geostationary satellite communication network. Critical subsystems and problem areas are identified and addressed. Efforts have concentrated heavily on the space segment; however, the ground segment was considered concurrently to ensure cost efficiency and realistic operational constraints.

  9. Circuit-switch architecture for a 30/20-GHz FDMA/TDM geostationary satellite communications network

    Science.gov (United States)

    Ivancic, William D.

    1992-01-01

    A circuit switching architecture is described for a 30/20 GHz frequency division, multiple access uplink/time division multiplexed downlink (FDMA/TDM) geostationary satellite communications network. Critical subsystems and problem areas are identified and addressed. Work was concentrated primarily on the space segment; however, the ground segment was considered concurrently to ensure cost efficiency and realistic operational constraints.

  10. Destination-directed, packet-switching architecture for 30/20-GHz FDMA/TDM geostationary communications satellite network

    Science.gov (United States)

    Ivancic, William D.; Shalkhauser, Mary JO

    1992-01-01

    A destination-directed packet switching architecture for a 30/20-GHz frequency division multiple access/time division multiplexed (FDMA/TDM) geostationary satellite communications network is discussed. Critical subsystems and problem areas are identified and addressed. Efforts have concentrated heavily on the space segment; however, the ground segment has been considered concurrently to ensure cost efficiency and realistic operational constraints.

  11. An overview of neural network applications for soil moisture retrieval from radar satellite sensors

    Science.gov (United States)

    Santi, E.; Paloscia, S.; Pettinato, S.

    2014-10-01

    Frequent and spatially distributed measurements of soil moisture (SMC), at different spatial scales, are advisable for all applications related to the environmental disciplines, such as climatology, meteorology, hydrology and agriculture. Satellite sensors operating in the low part of microwave spectrum are very suitable for this purpose, and their signals can be directly related to the moisture content of the observed surfaces, provided that all the contributions from soil and vegetation to the measured signal are properly accounted for. Among the algorithms used for the retrieval of SMC from both active (i.e. Synthetic Aperture Radar, SAR or real aperture radars) and passive (radiometers) microwave sensors, the artificial neural networks (ANN) represent the best compromise between accuracy and computation speed. ANN based algorithms have been developed at IFAC, and adapted to several radar and radiometric satellite sensors, in order to generate SMC products at different spatial resolutions, varying from hundreds of meters to tens of kilometers. These algorithms, which use the ANN techniques for inverting theoretical and semi-empirical models, such as Advanced Integral Equation (AIEM), Oh models, and Radiative transfer Theory (RTT), have been adapted to the C-band acquisitions from SAR (Envisat/ASAR) and real aperture radar (ASCAT) and to the X-band SAR acquisitions of Cosmo-SkyMed and TerraSAR-X. Moreover, a specific ANN algorithm has also been implemented for the L-band active and passive acquisitions of the incoming SMAP mission. The latter satellite will carry onboard simultaneously one radar and one radiometer operating at the same frequency, but with different spatial resolutions (3 and 40 km, respectively). Large datasets of co-located satellite acquisitions and direct SMC measurements on several test sites located worldwide have been used along with simulations derived from forward electromagnetic models for setting up, training and validating these

  12. BEATING ISIS IN THE DIGITAL SPACE: FOCUS TESTING ISIS DEFECTOR COUNTER-NARRATIVE VIDEOS WITH AMERICAN COLLEGE STUDENTS

    Directory of Open Access Journals (Sweden)

    Allision McDowell-Smith

    2017-03-01

    Full Text Available ISIS recruits on a 24/7 basis in over 21 languages over the Internet using videos, memes, tweets and other social media postings and swarming in on anyone that retweets, likes or endorses their materials to try to seduce them into the group. Their unprecedented social media drive has resulted in over 30,000 foreign fighters from more than 100 countries migrating to Syria and Iraq. ISIS recruitment in the U.S. is for the most part Internet based and has resulted in the actual and attempted recruitment of over 100 individuals residing in the U.S. with over 200 Americans traveling to Syria to join terrorist groups. To date very little counter-narrative material exists and most of it is cognitive versus emotionally impactful. The International Center for the Study of Violent Extremism (ICSVE Breaking the ISIS Brand – the ISIS Defectors Interviews Project has managed to collect 43 ISIS defector interviews and thus far produce two video clips of ISIS defectors denouncing the group which were focus tested in this research in a small normative college student sample of 75 undergraduate students. The results demonstrate that American college students find the videos authentic, disturbing and turn them away from ISIS, fulfilling the goals that the project is aiming for in producing counter-narrative materials.

  13. Integrated Services Digital Network (ISDN) status and opportunities for satellite systems

    Science.gov (United States)

    Casas, J. M.; Burke, W. R.

    1987-05-01

    The driving force behind the proposed Integrated Digital Services Network (ISDN) is identified as PTT's and industry. It is doubtful whether ISDN can satisfy business user requirements. For residential users, the prospects are even more uncertain, since the costs associated with the implementation of subscriber loops seem to be out of all proportion to the added value offered to end users in terms of new services. The evolution of IDN in Europe is such that it will leave substantial areas without digital connectivity for many years; morever, the transition from IDN to ISDN still requires the solution of many important problems at different levels of the network. Although ISDN can be expected to be offered gradually at national level in several countries in the coming years, access on a European scale will not be possible to any significant degree before the year 2000 and it will continue to remain unclear whether this offer will correspond to a real demand. It is shown that satellites could be of considerable help in solving Europe's communications problems. By providing instant coverage of the entire West European region, they can offer the benefits of ISDN wherever they are required.

  14. Delay analysis of an integrated voice and data access protocol with collision detection for multimedia satellite networks

    Science.gov (United States)

    Poon, Charles C. K.; Suda, Tatsuya

    1992-03-01

    The novel multiple-access scheme for multimedia satellite networks presented is based on a combination of FDMA and TDMA, integrating both circuit and packet-switching techniques. While the circuit-switching method is used to transmit such stream-type traffic as real-time voice communications, packet-switching is used to transmit such 'bursty' traffic as interactive data. A ground radio network is assumed for control signaling; the tone sense multiple access/partial collision detection scheme is implemented on this network to enhance the integrated access scheme's performance.

  15. Industry leading satellite based GNSS (Global Navigation Satellite System) positioning and monitoring solutions with real-time CORS (Continuously Operating Reference Station) networks

    Science.gov (United States)

    Janousek, Martin

    2010-05-01

    Real-Time CORS (Continuously Operating Reference Station Networks) today are typically GNSS networks for positioning and monitoring purposes. Real-Time networks can consist of a few stations for a local network up to nation- or continental wide networks with several hundred CORS stations. Such networks use wide area modeling of GNSS error sources including ionospheric, tropospheric and satellite orbit correction parameters to produce highest precision and efficiency method of positioning using GNSS. In 1998 Trimble Navigation Ltd. introduced a method of surveying with a non-physical or computed base station, called VRS (Virtual Reference Station). It is the most widely supported method of producing a network solution for precise carrier phase positioning in the industry. Surveying historically required one base as the fixed point of reference, and one or multiple rovers using that point of reference to compute their location by processing a vector result, either in real-time or in a postprocessed sense. Real-time survey is often referred to as RTK, short for real-time kinematic, and as the name suggests the results are in real time and you can move. The power of VRS is in the ability to compute a real-time wide-area solution to the factors that cause single base methods to degrade with distance. Namely, ionospheric and tropospheric modeling, and satellite orbit corrections. This is achieved by the reference network of CORS. A wide scattering of CORS across a state, typically 50-70km in mid-latitudes, creates a ground based sampling which significantly reduces the distance dependent errors that accumulate in the single base-rover relationship described early. Furthermore, GNSS networks can be used for real-time monitoring purposes at various distance range. Trimble Integrity Manager software provides a suite of motion engines designed to detect and quantify any movement in a range of scales from slow, creeping movement like subsidence, through sudden events such as

  16. ISI Proceedings数据库检索方法

    Institute of Scientific and Technical Information of China (English)

    杨伟娜

    2008-01-01

    本文在简述ISI Proceedings数据库及功能的基础上,分别从快速检索、普通检索、高级检索三个不同的检索途径介绍了ISI Proceedings数据库的检索方法及主要功能,并举例说明了若干检索技巧。

  17. Swarm Utilisation Analysis: LEO satellite observations for the ESA's SSA Space Weather network

    Science.gov (United States)

    Kervalishvili, Guram; Stolle, Claudia; Rauberg, Jan; Olsen, Nils; Vennerstrøm, Susanne; Gullikstad Johnsen, Magnar; Hall, Chris

    2017-04-01

    ESA's (European Space Agency) constellation mission Swarm was successfully launched on 22 November 2013. The three satellites achieved their final constellation on 17 April 2014 and since then Swarm-A and Swarm-C orbiting the Earth at about 470 km (flying side-by-side) and Swarm-B at about 520 km altitude. Each of Swarm satellite carries instruments with high precision to measure magnetic and electric fields, neutral and plasma densities, and TEC (Total Electron Content) for which a dual frequency GPS receiver is used. SUA (Swarm Utilisation Analysis) is a project of the ESA's SSA (Space Situational Awareness) SWE (Space Weather) program. Within this framework GFZ (German Research Centre for Geosciences, Potsdam, Germany) and DTU (National Space Institute, Kongens Lyngby, Denmark) have developed two new Swarm products ROT (Rate Of change of TEC) and PEJ (Location and intensity level of Polar Electrojets), respectively. ROT is derived as the first time derivative from the Swarm measurements of TEC at 1 Hz sampling. ROT is highly relevant for users in navigation and communications: strong plasma gradients cause GPS signal degradation or even loss of GPS signal. Also, ROT is a relevant space weather asset irrespective of geomagnetic activity, e.g., high amplitude values of ROT occur during all geomagnetic conditions. PEJ is derived from the Swarm measurements of the magnetic field strength at 1 Hz sampling. PEJ has a high-level importance for power grid companies since the polar electrojet is a major cause for ground-induced currents. ROT and PEJ together with five existing Swarm products TEC, electron density, IBI (Ionospheric Bubble Index), FAC (Field-Aligned Current), and vector magnetic field build the SUA service prototype. This prototype will be integrated into ESA's SSA Space Weather network as a federated service and will be available soon from ESA's SSA SWE Ionospheric Weather and Geomagnetic Conditions Expert Service Centres (ESCs).

  18. Contribution of MODIS Derived Snow Cover Satellite Data into Artificial Neural Network for Streamflow Estimation

    Science.gov (United States)

    Uysal, Gokcen; Arda Sorman, Ali; Sensoy, Aynur

    2014-05-01

    Contribution of snowmelt and correspondingly snow observations are highly important in mountainous basins for modelers who deal with conceptual, physical or soft computing models in terms of effective water resources management. Long term archived continuous data are needed for appropriate training and testing of data driven approaches like artificial neural networks (ANN). Data is scarce at the upper elevations due to the difficulty of installing sufficient automated SNOTEL stations; thus in literatures many attempts are made on the rainfall dominated basins for streamflow estimation studies. On the other hand, optical satellites can easily detect snow because of its high reflectance property. MODIS (Moderate Resolution Imaging Spectroradiometer) satellite that has two platforms (Terra and Aqua) provides daily and 8-daily snow images for different time periods since 2000, therefore snow cover data (SCA) may be useful as an input layer for ANN applications. In this study, a multi-layer perceptron (MLP) model is trained and tested with precipitation, temperature, radiation, previous day discharges as well as MODIS daily SCA data. The weights and biases are optimized with fastest and robust Levenberg-Marquardt backpropagation algorithm. MODIS snow cover images are removed from cloud coverage using certain filtering techniques. The Upper Euphrates River Basin in eastern part of Turkey (10 250 km2) is selected as the application area since it is fed by snowmelt approximately 2/3 of total annual volume during spring and early summer. Several input models and ANN structures are investigated to see the effect of the contributions using 10 years of data (2001-2010) for training and validation. The accuracy of the streamflow estimations is checked with statistical criteria (coefficient of determination, Nash-Sutcliffe model efficiency, root mean square error, mean absolute error) and the results seem to improve when SCA data is introduced. Furthermore, a forecast study is

  19. Comparison of global irradiance measurements of the official Spanish radiometric network for 2006 with satellite estimated data

    Directory of Open Access Journals (Sweden)

    J. M. Sancho

    2011-01-01

    Full Text Available The monthly average values of daily global irradiance measured in broadband at 40 stations of the National Radiometric Network of the Spanish Meteorological Agency have been compared with the monthly values of SIS (Surface Incoming Shortwave radiation of the Climate Monitoring-Satellite Application Facility for 2006. It is calculated by the data from the instrument Spinning Enhanced Visible and Infrared Imager of the Meteosat Second Generation satellite and of the Advanced Very High Resolution Radiometer of the NOAA polar satellites. The results show a great similarity between the data from both sources of information, and the discrepancies found are around 5%. The aim of such a comparison is to evaluate the suitability of the use of the SIS data for the elaboration of an atlas of solar irradiance available in Spain.

  20. Alternative packet switch architectures for a 30/20 GHz FDMA/TDMA geostationary communication satellite network

    Science.gov (United States)

    Stehle, Roy; Ogier, Richard G.

    1995-01-01

    This study has investigated alternatives for realizing a packet-based network switch for deployment on a communication satellite. The emphasis was on the avoidance of contention problems that can occur due to the simultaneous arrival of an excessive number of packets destined for the same downlink dwell. The study was to look ahead, beyond the current Advanced Communications Technology Satellite (ACTS) capability, to the next generation of satellites. The study has not been limited by currently available technology, but has used university and commercial research efforts as a basis for designs that can be readily constructed and launched within the next five years. Tradeoffs in memory requirement, power requirement, and architecture have been considered as a part of our study.

  1. Spatiotemporal interpolation of discharge across a river network by using synthetic SWOT satellite data

    Science.gov (United States)

    Paiva, Rodrigo C. D.; Durand, Michael T.; Hossain, Faisal

    2015-01-01

    Recent efforts have sought to estimate river discharge and other surface water-related quantities using spaceborne sensors, with better spatial coverage but worse temporal sampling as compared with in situ measurements. The Surface Water and Ocean Topography (SWOT) mission will provide river discharge estimates globally from space. However, questions on how to optimally use the spatially distributed but asynchronous satellite observations to generate continuous fields still exist. This paper presents a statistical model (River Kriging-RK), for estimating discharge time series in a river network in the context of the SWOT mission. RK uses discharge estimates at different locations and times to produce a continuous field using spatiotemporal kriging. A key component of RK is the space-time river discharge covariance, which was derived analytically from the diffusive wave approximation of Saint Venant's equations. The RK covariance also accounts for the loss of correlation at confluences. The model performed well in a case study on Ganges-Brahmaputra-Meghna (GBM) River system in Bangladesh using synthetic SWOT observations. The correlation model reproduced empirically derived values. RK (R2=0.83) outperformed other kriging-based methods (R2=0.80), as well as a simple time series linear interpolation (R2=0.72). RK was used to combine discharge from SWOT and in situ observations, improving estimates when the latter is included (R2=0.91). The proposed statistical concepts may eventually provide a feasible framework to estimate continuous discharge time series across a river network based on SWOT data, other altimetry missions, and/or in situ data.

  2. Using remote sensing satellite data and artificial neural network for prediction of potato yield in Bangladesh

    Science.gov (United States)

    Akhand, Kawsar; Nizamuddin, Mohammad; Roytman, Leonid; Kogan, Felix

    2016-09-01

    Potato is one of the staple foods and cash crops in Bangladesh. It is widely cultivated in all of the districts and ranks second after rice in production. Bangladesh is the fourth largest potato producer in Asia and is among the world's top 15 potato producing countries. The weather condition for potato cultivation is favorable during the sowing, growing and harvesting period. It is a winter crop and is cultivated during the period of November to March. Bangladesh is mainly an agricultural based country with respect to agriculture's contribution to GDP, employment and consumption. Potato is a prominent crop in consideration of production, its internal demand and economic value. Bangladesh has a big economic activities related to potato cultivation and marketing, especially the economic relations among farmers, traders, stockers and cold storage owners. Potato yield prediction before harvest is an important issue for the Government and the stakeholders in managing and controlling the potato market. Advanced very high resolution radiometer (AVHRR) based satellite data product vegetation health indices VCI (vegetation condition index) and TCI (temperature condition index) are used as predictors for early prediction. Artificial neural network (ANN) is used to develop a prediction model. The simulated result from this model is encouraging and the error of prediction is less than 10%.

  3. Learning Oriented Region-based Convolutional Neural Networks for Building Detection in Satellite Remote Sensing Images

    Science.gov (United States)

    Chen, C.; Gong, W.; Hu, Y.; Chen, Y.; Ding, Y.

    2017-05-01

    The automated building detection in aerial images is a fundamental problem encountered in aerial and satellite images analysis. Recently, thanks to the advances in feature descriptions, Region-based CNN model (R-CNN) for object detection is receiving an increasing attention. Despite the excellent performance in object detection, it is problematic to directly leverage the features of R-CNN model for building detection in single aerial image. As we know, the single aerial image is in vertical view and the buildings possess significant directional feature. However, in R-CNN model, direction of the building is ignored and the detection results are represented by horizontal rectangles. For this reason, the detection results with horizontal rectangle cannot describe the building precisely. To address this problem, in this paper, we proposed a novel model with a key feature related to orientation, namely, Oriented R-CNN (OR-CNN). Our contributions are mainly in the following two aspects: 1) Introducing a new oriented layer network for detecting the rotation angle of building on the basis of the successful VGG-net R-CNN model; 2) the oriented rectangle is proposed to leverage the powerful R-CNN for remote-sensing building detection. In experiments, we establish a complete and bran-new data set for training our oriented R-CNN model and comprehensively evaluate the proposed method on a publicly available building detection data set. We demonstrate State-of-the-art results compared with the previous baseline methods.

  4. AERONET-OC: Strengths and Weaknesses of a Network for the Validation of Satellite Coastal Radiometric Products

    Science.gov (United States)

    Zibordi, Giuseppe; Holben, Brent; Slutsker, Ilya; Giles, David; D'Alimonte, Davide; Melin, Frederic; Berthon, Jean-Francois; Vandemark, Doug; Feng, Hui; Schuster, Gregory; Fabbri, Bryan E.; Kaitala, Seppo; Seppala, Jukka

    2008-01-01

    The Ocean Color component of the Aerosol Robotic Network (AERONET-OC) has been implemented to support long-term satellite ocean color investigations through cross-site consistent and accurate measurements collected by autonomous radiometer systems deployed on offshore fixed platforms. The ultimate purpose of AERONET-OC is the production of standardized measurements performed at different sites with identical measuring systems and protocols, calibrated using a single reference source and method, and processed with the same code. The AERONET-OC primary data product is the normalized water leaving radiance determined at center-wavelengths of interest for satellite ocean color applications, with an uncertainty lower than 5% in the blue-green spectral regions and higher than 8% in the red. Measurements collected at 6 sites counting the northern Adriatic Sea, the Baltic Proper, the Gulf of Finland, the Persian Gulf, and, the northern and southern margins of the Middle Atlantic Bay, have shown the capability of producing quality assured data over a wide range of bio-optical conditions including Case-2 yellow substance- and sedimentdominated waters. This work briefly introduces network elements like: deployment sites, measurement method, instrument calibration, processing scheme, quality-assurance, uncertainties, data archive and products accessibility. Emphases is given to those elements which underline the network strengths (i.e., mostly standardization of any network element) and its weaknesses (i.e., the use of consolidated, but old-fashioned technology). The work also addresses the application of AERONET-OC data to the validation of primary satellite radiometric products over a variety of complex coastal waters and finally provides elements for the identification of new deployment sites most suitable to support satellite ocean color missions.

  5. Robust adjustment of a geodetic network measured by satellite technology in the Dargovských Hrdinov suburb

    Directory of Open Access Journals (Sweden)

    Slavomír Labant

    2011-12-01

    Full Text Available This article addresses the adjustment of a 3D geodetic network in the Dargovských Hrdinov suburbs using Global Navigation SatelliteSystems (GNSS for the purposes of deformation analysis. The advantage of using the GNSS compared to other terrestrial technology is thatit is not influenced by unpredictability in the ground level atmosphere and individual visibilities between points in the observed network arenot necessary. This article also includes the planning of GNSS observations using Planning Open Source software from Trimble as well assubsequent observations at individual network points. The geodetic network is processing on the basis of the Gauss-Markov model usingthe least square method and robust adjustment. From robust methods, Huber’s Robust M-estimation and Hampel’s Robust M-estimationwere used. Individual adjustments were tested and subsequently the results of analysis were graphically visualised using absolute confidenceellipsoids.

  6. Measuring QoS in an Aeronautical Opportunistic Network Architecture with Limited Access to a Satellite Communications Backhaul

    Directory of Open Access Journals (Sweden)

    Rubén Martínez-Vidal

    2016-01-01

    Full Text Available We measure quality of service (QoS in a wireless network architecture of transoceanic aircraft. A distinguishing characteristic of the network scheme we analyze is that it mixes the concept of Delay Tolerant Networking (DTN through the exploitation of opportunistic contacts, together with direct satellite access in a limited number of the nodes. We provide a graph sparsification technique for deriving a network model that satisfies the key properties of a real aeronautical opportunistic network while enabling scalable simulation. This reduced model allows us to analyze the impact regarding QoS of introducing Internet-like traffic in the form of outgoing data from passengers. Promoting QoS in DTNs is usually really challenging due to their long delays and scarce resources. The availability of satellite communication links offers a chance to provide an improved degree of service regarding a pure opportunistic approach, and therefore it needs to be properly measured and quantified. Our analysis focuses on several QoS indicators such as delivery time, delivery ratio, and bandwidth allocation fairness. Obtained results show significant improvements in all metric indicators regarding QoS, not usually achievable on the field of DTNs.

  7. Research on a New Program of Satellite Network Security Certification%一种新型卫星网络安全认证方案的研究

    Institute of Scientific and Technical Information of China (English)

    高婧; 朱晨光

    2011-01-01

    在卫星网络通信中,卫星的安全防护是卫星通信系统建设的重要内容之一.结合卫星网络的特点,在对卫星网络的安全认证需求进行分析的基础上,提出了一种基于ELGamal数字签名的卫星网络安全双向认证方案,以解决卫星干扰、非法盗用卫星资源的问题;克服了传统认证方案中普遍存在的认证效率较低和认证过程较复杂等问题,如将该方案加以推广,可以广泛采用.%In the communication of satellite network, the security of satellite is an important content in the development of satellite communication system.Combining with the characteristics of satellite network and analyzing the safety certification requirements of satellite network, a two-way satellite network security certification program based on EIGamal digital signature is introduced to address the satellite interference, illegal use of satellite resources, and overcome the low efficiency and complex process certification existed in traditional common certification.This program can he widely adopted.

  8. Combined Geometric and Neural Network Approach to Generic Fault Diagnosis in Satellite Actuators and Sensors

    DEFF Research Database (Denmark)

    Baldi, P.; Blanke, Mogens; Castaldi, P.

    2016-01-01

    This paper presents a novel scheme for diagnosis of faults affecting the sensors measuring the satellite attitude, body angular velocity and flywheel spin rates as well as defects related to the control torques provided by satellite reaction wheels. A nonlinear geometric design is used to avoid...... on a detailed nonlinear satellite model with embedded disturbance description. The results document the efficacy of the proposed diagnosis scheme....

  9. A Methodology For Measuring Resilience in a Satellite-Based Communication Network

    Science.gov (United States)

    2014-03-27

    In the cyber realm, most satellite operators were in compliance with the National Security Agency’s (NSA) approved encryptions for transmissions...and more continue to meet compliance as new satellites are placed in orbit. Along with the encryptions , many 17 satellite operators utilize “deaf...nation at war may be of higher concern than the nation providing backdoor support which is higher than a neutral nation, and so on until a region not

  10. Satellite/Terrestrial Networks: End-to-End Communication Interoperability Quality of Service Experiments

    Science.gov (United States)

    Ivancic, William D.

    1998-01-01

    Various issues associated with satellite/terrestrial end-to-end communication interoperability are presented in viewgraph form. Specific topics include: 1) Quality of service; 2) ATM performance characteristics; 3) MPEG-2 transport stream mapping to AAL-5; 4) Observation and discussion of compressed video tests over ATM; 5) Digital video over satellites status; 6) Satellite link configurations; 7) MPEG-2 over ATM with binomial errors; 8) MPEG-2 over ATM channel characteristics; 8) MPEG-2 over ATM over emulated satellites; 9) MPEG-2 transport stream with errors; and a 10) Dual decoder test.

  11. PENERAPAN MICRO CDS/ISIS UNTUK PENGELOLAAN INFORMASI

    Directory of Open Access Journals (Sweden)

    Rukasih Dardjat

    2011-12-01

    Full Text Available Penggunaan komputer untuk penyimpanan dan pencarian kembali informasi sudah banyak dilakukan oleh beberapa perpustakaan, pusat informasi, pusat dokumentasi, dan lain-lain.CDS/ISIS (Computerized Documentation Systems/Integrated Set of Information Systems, adalah suatu sistem penyimpanan dan pencarian kembali informasi pada umumnya, yang dirancang secara khusus untuk pengelolaan pangkalan data yang bukan numerik (non-numerical data base dengan menggunakan komputer.Micro CDS/ISIS Software Package merupakan paket piranti lunak yang dikembangkan oleh Unesco (Copyright Unesco, 1985, yang sistem pengelolaannya dapat dioperasikan dengan menggunakan komputer mikro (IBM PC XT/AT, IBM Compatible, Olivetti PC, dan lain-lain.Paket perangkat lunak Nicro CDS/ISIS terdiri dari satu set program-program komputer yang setiap program mempunyai fungsi khusus untuk mengolah serta memproses elemen-elemen data yang berbeda sama sekali untuk menjadi suatu informasi tertentu yang sesuai dengan keinginan para pengguna.

  12. Developing a new global network of river reaches from merged satellite-derived datasets

    Science.gov (United States)

    Lion, C.; Allen, G. H.; Beighley, E.; Pavelsky, T.

    2015-12-01

    In 2020, the Surface Water and Ocean Topography satellite (SWOT), a joint mission of NASA/CNES/CSA/UK will be launched. One of its major products will be the measurements of continental water extent, including the width, height, and slope of rivers and the surface area and elevations of lakes. The mission will improve the monitoring of continental water and also our understanding of the interactions between different hydrologic reservoirs. For rivers, SWOT measurements of slope must be carried out over predefined river reaches. As such, an a priori dataset for rivers is needed in order to facilitate analysis of the raw SWOT data. The information required to produce this dataset includes measurements of river width, elevation, slope, planform, river network topology, and flow accumulation. To produce this product, we have linked two existing global datasets: the Global River Widths from Landsat (GRWL) database, which contains river centerline locations, widths, and a braiding index derived from Landsat imagery, and a modified version of the HydroSHEDS hydrologically corrected digital elevation product, which contains heights and flow accumulation measurements for streams at 3 arcsecond spatial resolution. Merging these two datasets requires considerable care. The difficulties, among others, lie in the difference of resolution: 30m versus 3 arseconds, and the age of the datasets: 2000 versus ~2010 (some rivers have moved, the braided sections are different). As such, we have developed custom software to merge the two datasets, taking into account the spatial proximity of river channels in the two datasets and ensuring that flow accumulation in the final dataset always increases downstream. Here, we present our preliminary results for a portion of South America and demonstrate the strengths and weaknesses of the method.

  13. Integrating Satellite, Aircraft, and Ground-Based Observations to Improve a GHG Inventory Network

    Science.gov (United States)

    Midzik, M.; Abbate, J.; Raheja, G.

    2016-12-01

    Methane (CH4) is the second-most effective greenhouse gas, with a global warming potential up to 70 times that of carbon dioxide (CO2) over the span of 25 years. With a majority of these emissions attributed to livestock, landfill, and wastewater treatment, CH4 emissions are a concern for both urban and rural landscapes. Though Earth-observing satellites can effectively monitor mid-to-upper tropospheric CH4 on a global scale, current instrumentation is limited in its capacity to accurately measure near-surface CH4 on a local scale. The Bay Area Air Quality Management District (BAAQMD) regulates stationary sources of air pollution in the nine counties surrounding San Francisco Bay. BAAQMD traditionally estimates emissions using a bottom-up approach, combining emissions factor and activity data to estimate source emissions per sector. However, recent literature suggests that these bottom-up approaches are underestimating CH4 emissions by nearly 50% in many regions of California. In efforts to address the discrepancy, this project compares BAAQMD's current CH4 spatial emissions inventory with top-down sub-Planetary Boundary Layer aircraft measurements from the NASA Alpha Jet Atmospheric eXperiment (AJAX). Together, these different approaches were used to identify CH4 hot-spots in the San Francisco Bay Area. In addition, sources of high-CH4 anomalies were identified using USGS high resolution aerial imagery and trajectory analysis. Furthermore, this project used NASA Landsat 8 imagery and USGS orthoimagery to classify the types of indicated emissions and infer other points of interest not included in the current BAAQMD inventory. These findings help pinpoint specific sites for BAAQMD's upcoming Mobile GHG Measurement Network; furthermore, results from this project suggest future sites for coincident data collection between advancing bottom-up and top-down instruments.

  14. New Online Ecology of Adversarial Aggregates: ISIS and beyond

    CERN Document Server

    Johnson, N F; Vorobyeva, Y; Gabriel, A; Qi, H; Velasquez, N; Manrique, P; Johnson, D; Restrepo, E; Song, C; Wuchty, S

    2016-01-01

    Support for an extremist entity such as Islamic State (ISIS) somehow manages to survive globally online despite significant external pressure, and may ultimately inspire acts by individuals who have no prior history of extremism, formal cell membership or direct links to leadership. We uncover an ultrafast ecology driving this online support and provide a mathematical theory that describes it. The ecology features self-organized aggregates that proliferate preceding the onset of recent real-world campaigns, and adopt novel adaptive mechanisms to enhance their survival. One of the actionable predictions is that the development of large, potentially potent pro-ISIS aggregates can be thwarted by targeting smaller ones.

  15. PENETAPAN KADAR ZAT BESI (Fe PADA BUAH NAGA ISI SUPER MERAH (Hylocereus costaricensis L. DAN ISI PUTIH (Hylocereus undatus L.

    Directory of Open Access Journals (Sweden)

    Dira Dira

    2014-12-01

    Full Text Available AbstrakTelah dilakukan penelitian yang bertujuan untuk menetapkan kadar zat besi (Fe pada buah naga isi super merah (Hylocereus costaricensis L. dan buah naga isi putih (Hylocereus undatus L. dengan metode Spektrofotometri Serapan Atom. Masing-masing sampel di destruksi terlebih dahulu dengan melakukan destruksi kering, kemudian serapan larutan sampel diukur dengan alat Spektrofotometer Serapan Atom menggunakan lampu katoda berongga Fe pada panjang gelombang 248,3 nm. Hasil penelitian menunjukkan kadar zat besi pada buah naga isi super merah (Hylocereus costaricensis L. adalah 0,03673 %b/b dan buah naga isi putih (Hylocereus undatus L. adalah 0,04295 %b/b. Analisa statistik menggunakan uji T-student didapatkan hasil yang tidak berbeda nyata antara kadar Fe pada buah naga isi super merah (Hylocereus costaricensis L. dan buah naga isi putih (Hylocereus undatus L. pada P < 0,05.AbstractA research to determination of Iron (Fe content in red dragon fruit (Hylocereus costaricensis L. and white dragon fruit (Hylocereus undatus L. has been done by using the Atomic Absorbtion Spectroscopy. Each sample were destructing first,with dry destruction, than the absorbtion of solution was measured with Atomic Absorbtion Spectroscopy using Hollow Catode Lamp Fe at wave length 248,3 nm. The result show that Fe content in red dragon fruit (Hylocereus costaricensis L. is 0,03673 % w/w and white dragon fruit (Hylocereus undatus L. is 0,04295 % w/w. Statistic analisys using T-students found that there is no significant result of Fe content between red dragon fruit (Hylocereus costaricensis L. and white dragon fruit (Hylocereus undatus L. at P < 0,05.

  16. Design of a search and rescue terminal based on the dual-mode satellite and CDMA network

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The current goal is to create a set of portable terminals with GPS/BD2 dual-mode satellite positioning, vital signs monitoring and wireless transmission functions. The terminal depends on an ARM processor to collect and combine data related to vital signs and GPS/BD2 location information, and sends the message to headquarters through the military CDMA network. It integrates multiple functions as a whole. The satellite positioning and wireless transmission capabilities are integrated into the motherboard, and the vital signs sensors used in the form of belts communicate with the board through Bluetooth. It can be adjusted according to the headquarters’ instructions. This kind of device is of great practical significance for operations during disaster relief, search and rescue of the wounded in wartime, non-war military operations and other special circumstances.

  17. Design of a search and rescue terminal based on the dual-mode satellite and CDMA network

    Science.gov (United States)

    Zhao, Junping; Zhang, Xuan; Zheng, Bing; Zhou, Yubin; Song, Hao; Song, Wei; Zhang, Meikui; Liu, Tongze; Zhou, Li

    2010-12-01

    The current goal is to create a set of portable terminals with GPS/BD2 dual-mode satellite positioning, vital signs monitoring and wireless transmission functions. The terminal depends on an ARM processor to collect and combine data related to vital signs and GPS/BD2 location information, and sends the message to headquarters through the military CDMA network. It integrates multiple functions as a whole. The satellite positioning and wireless transmission capabilities are integrated into the motherboard, and the vital signs sensors used in the form of belts communicate with the board through Bluetooth. It can be adjusted according to the headquarters' instructions. This kind of device is of great practical significance for operations during disaster relief, search and rescue of the wounded in wartime, non-war military operations and other special circumstances.

  18. Dynamic Neural Network-Based Pulsed Plasma Thruster (PPT) Fault Detection and Isolation for Formation Flying of Satellites

    Science.gov (United States)

    Valdes, A.; Khorasani, K.

    The main objective of this paper is to develop a dynamic neural network-based fault detection and isolation (FDI) scheme for the Pulsed Plasma Thrusters (PPTs) that are used in the Attitude Control Subsystem (ACS) of satellites that are tasked to perform a formation flying mission. By using data collected from the relative attitudes of the formation flying satellites our proposed "High Level" FDI scheme can detect the pair of thrusters which is faulty, however fault isolation cannot be accomplished. Based on the "High Level" FDI scheme and the DNN-based "Low Level" FDI scheme developed earlier by the authors, an "Integrated" DNN-based FDI scheme is then proposed. To demonstrate the FDI capabilities of the proposed schemes various fault scenarios are simulated.

  19. The Isis Problem and the Question of Representations.

    Science.gov (United States)

    Davis, Robert B.

    1993-01-01

    Presents two solutions of the Isis Problem, finding the dimensions of a rectangle for which the numerical values of the area and perimeter are equal, to hypothesize how the ancient Egyptians may have solved the problem without the benefits of more modern mathematics. (MDH)

  20. General-purpose isiZulu speech synthesiser

    CSIR Research Space (South Africa)

    Louw, A

    2005-07-01

    Full Text Available A general-purpose isiZulu text-to-speech (TTS) system was developed, based on the “Multisyn” unit-selection approach supported by the Festival TTS toolkit. The development involved a number of challenges related to the interface between speech...

  1. Energy-Efficient Network Transmission between Satellite Swarms and Earth Stations Based on Lyapunov Optimization Techniques

    Directory of Open Access Journals (Sweden)

    Weiwei Fang

    2014-01-01

    Full Text Available The recent advent of satellite swarm technologies has enabled space exploration with a massive number of picoclass, low-power, and low-weight spacecraft. However, developing swarm-based satellite systems, from conceptualization to validation, is a complex multidisciplinary activity. One of the primary challenges is how to achieve energy-efficient data transmission between the satellite swarm and terrestrial terminal stations. Employing Lyapunov optimization techniques, we present an online control algorithm to optimally dispatch traffic load among different satellite-ground links for minimizing overall energy consumption over time. Our algorithm is able to independently and simultaneously make control decisions on traffic dispatching over intersatellite-links and up-down-links so as to offer provable energy and delay guarantees, without requiring any statistical information of traffic arrivals and link condition. Rigorous analysis and extensive simulations have demonstrated the performance and robustness of the proposed new algorithm.

  2. Monitoring Animal Behaviour and Environmental Interactions Using Wireless Sensor Networks, GPS Collars and Satellite Remote Sensing

    National Research Council Canada - National Science Library

    Handcock, Rebecca N; Swain, Dave L; Bishop-Hurley, Greg J; Patison, Kym P; Wark, Tim; Valencia, Philip; Corke, Peter; O'Neill, Christopher J

    2009-01-01

    ...). We explore this concept using a case-study from an extensive cattle enterprise in northern Australia and demonstrate the potential for combining GPS collars and satellite images in a WSN to monitor...

  3. Satellite- and Epoch Differenced Precise Point Positioning Based on a Regional Augmentation Network

    Directory of Open Access Journals (Sweden)

    Bin Wu

    2012-06-01

    Full Text Available Precise Point Positioning (PPP has been demonstrated as a simple and effective approach for user positioning. The key issue in PPP is how to shorten convergence time and improve positioning efficiency. Recent researches mainly focus on the ambiguity resolution by correcting residual phase errors at a single station. The success of this approach (referred to hereafter as NORM-PPP is subject to how rapidly one can fix wide-lane and narrow-lane ambiguities to achieve the first ambiguity-fixed solution. The convergence time of NORM-PPP is receiver type dependent, and normally takes 15–20 min. Different from the general algorithm and theory by which the float ambiguities are estimated and the integer ambiguities are fixed, we concentrate on a differential PPP approach: the satellite- and epoch differenced (SDED approach. In general, the SDED approach eliminates receiver clocks and ambiguity parameters and thus avoids the complicated residual phase modeling procedure. As a further development of the SDED approach, we use a regional augmentation network to derive tropospheric delay and remaining un-modeled errors at user sites. By adding these corrections and applying the Robust estimation, the weak mathematic properties due to the ED operation is much improved. Implementing this new approach, we need only two epochs of data to achieve PPP positioning converging to centimeter-positioning accuracy. Using seven days of GPS data at six CORS stations in Shanghai, we demonstrate the success rate, defined as the case when three directions converging to desired positioning accuracy of 10 cm, reaches 100% when the interval between the two epochs is longer than 15 min. Comparing the results of 15 min’ interval to that of 10 min’, it is observed that the position RMS improves from 2.47, 3.95, 5.78 cm to 2.21, 3.93, 4.90 cm in the North, East and Up directions, respectively. Combining the SDED coordinates at the starting point and the ED relative

  4. Satellite- and epoch differenced precise point positioning based on a regional augmentation network.

    Science.gov (United States)

    Li, Haojun; Chen, Junping; Wang, Jiexian; Wu, Bin

    2012-01-01

    Precise Point Positioning (PPP) has been demonstrated as a simple and effective approach for user positioning. The key issue in PPP is how to shorten convergence time and improve positioning efficiency. Recent researches mainly focus on the ambiguity resolution by correcting residual phase errors at a single station. The success of this approach (referred to hereafter as NORM-PPP) is subject to how rapidly one can fix wide-lane and narrow-lane ambiguities to achieve the first ambiguity-fixed solution. The convergence time of NORM-PPP is receiver type dependent, and normally takes 15-20 min. Different from the general algorithm and theory by which the float ambiguities are estimated and the integer ambiguities are fixed, we concentrate on a differential PPP approach: the satellite- and epoch differenced (SDED) approach. In general, the SDED approach eliminates receiver clocks and ambiguity parameters and thus avoids the complicated residual phase modeling procedure. As a further development of the SDED approach, we use a regional augmentation network to derive tropospheric delay and remaining un-modeled errors at user sites. By adding these corrections and applying the Robust estimation, the weak mathematic properties due to the ED operation is much improved. Implementing this new approach, we need only two epochs of data to achieve PPP positioning converging to centimeter-positioning accuracy. Using seven days of GPS data at six CORS stations in Shanghai, we demonstrate the success rate, defined as the case when three directions converging to desired positioning accuracy of 10 cm, reaches 100% when the interval between the two epochs is longer than 15 min. Comparing the results of 15 min' interval to that of 10 min', it is observed that the position RMS improves from 2.47, 3.95, 5.78 cm to 2.21, 3.93, 4.90 cm in the North, East and Up directions, respectively. Combining the SDED coordinates at the starting point and the ED relative coordinates thereafter, we

  5. Three-month performance evaluation of the Nanometrics, Inc., Libra Satellite Seismograph System in the northern California Seismic Network

    Science.gov (United States)

    Oppenheimer, David H.

    2000-01-01

    In 1999 the Northern California Seismic Network (NCSN) purchased a Libra satellite seismograph system from Nanometrics, Inc to assess whether this technology was a cost-effective and robust replacement for their analog microwave system. The system was purchased subject to it meeting the requirements, criteria and tests described in Appendix A. In early 2000, Nanometrics began delivery of various components of the system, such as the hub and remote satellite dish and mounting hardware, and the NCSN installed and assembled most equipment in advance of the arrival of Nanometrics engineers to facilitate the configuration of the system. The hub was installed in its permanent location, but for logistical reasons the "remote" satellite hardware was initially configured at the NCSN for testing. During the first week of April Nanometrics engineers came to Menlo Park to configure the system and train NCSN staff. The two dishes were aligned with the satellite, and the system was fully operational in 2 days with little problem. Nanometrics engineers spent the remaining 3 days providing hands-on training to NCSN staff in hardware/software operation, configuration, and maintenance. During the second week of April 2000, NCSN staff moved the entire remote system of digitizers, dish assembly, and mounting hardware to Mammoth Lakes, California. The system was reinstalled at the Mammoth Lakes water treatment plant and communications successfully reestablished with the hub via the satellite on 14 April 2000. The system has been in continuous operation since then. This report reviews the performance of the Libra system for the three-month period 20 April 2000 through 20 July 2000. The purpose of the report is to assess whether the system passed the acceptance tests described in Appendix A. We examine all data gaps reported by NCSN "gap list" software and discuss their cause.

  6. ISIS and Social Media: The Combatant Commander’s Guide to Countering ISIS’s Social Media Campaign

    Science.gov (United States)

    2015-06-07

    ISIS – Another View and Analysis A far cry from how ISIS’s propaganda machine defines its own organization, Hasan offers this more realistic view...intelligence should be collated and integrated into the overall information campaign. Finally, DOD entities will need to work with civilian partners to

  7. The New Updates in CDS/ISIS for Windows : Version WIN/ISIS 1.5 .Part 1

    Directory of Open Access Journals (Sweden)

    Mohamed Salem Ghonem

    2006-03-01

    Full Text Available A Study about the last version of library system Win/ISIS 1.5, the study define the Parameters of the new version, and the components of each one and its function, and how to modify them.

  8. The New Updates in CDS/ISIS for Windows : Version WIN/ISIS 1.5 .Part 2

    Directory of Open Access Journals (Sweden)

    Mohamed Salem Ghonem

    2006-06-01

    Full Text Available A Study about the last version of library system Win/ISIS 1.5, the study define the Parameters of the new version, and the components of each one and its function, and how to modify them.

  9. A CDMA Spotbeam Architecture for the Next Generation Satellite System (NGSS) for the Aeronautical Telecommunications Network (ATN)

    Science.gov (United States)

    Raghavan, Rajesh S.; Shamma, Mohammed A.

    2003-01-01

    This paper will present work being done to model and simulate a CDMA based Mobile Satellite System architecture for providing all or part of the future Air Traffic Management (ATM) services. Such a system, will help in relieving the dependence on ground based networks, if not eliminate it. Additionally such an architecture can be used in parallel or as a supplementary service along with ground based links to help alleviate any capacity bottlenecks, or in areas where such services are difficult to make available such as in oceanic, remote areas outside the jet highways, or in developing countries where ground services are less available.

  10. Satellite altimetry and GOCE contribution to the pre-definition of the Kingdom of Saudi Arabia (KSA) Vertical Network

    Science.gov (United States)

    Vergos, Georgios S.; Grebenitcharsky, Rossen S.; Natsiopoulos, Dimitrios A.; Al-Kherayef, Othman; Al-Muslmani, Bandar

    2017-04-01

    The availability of a unified and well-established national vertical system and frame is of outmost importance in support of everyday geodetic, surveying and engineering applications. Vertical reference system (VRS) modernization and unification has gained increased importance especially during the last years due to the advent of gravity-field dedicated missions and GOCE in particular, since it is the first time that an unprecedented in accuracy dataset of gravity field functionals has become available at a global scale. The Kingdom of Saudi Arabia VRS is outdated and exhibits significant tilts and biases, so that during the last couple of years an extensive effort has been put forth in order to: re-measure by traditional levelling the entire network, establish new benchmarks (BMs), perform high-quality absolute and relative gravity observations and construct new tide-gauge (TG) stations in both the Arab and Red Seas. The Current work focuses on the combined analysis of the existing, recently collected, terrestrial observations with satellite altimetry data and the latest GOCE-based Earth Geopotential Models (EGMs) in order to provide a pre-definition of the KSA VRS. To that respect, a 30-year satellite altimetry time-series is constructed for each TG station in order to derive both the Mean Sea Level (MSL) as well as the sea level trends. This information is analyzed, through Wavelet (WL) Multi-resolution Analysis (MRA), with the TG sea level records in order to determine annual, semi-annual and secular trends of the Red and Arab Sea variations. Finally, the so-derived trends and MSL are combined with local gravity observations at the TG BMs, levelling offsets between the TGs and the network BMs, levelling observations between the network BMs themselves and GOCE-based EGM-derived geoid heights and potential values. The validation of GOCE contribution and of the satellite altimetry derived MSL and trends is based on a simultaneous adjustment of the entire KSA

  11. Energy-Efficient Transmissions for Remote Wireless Sensor Networks: An Integrated HAP/Satellite Architecture for Emergency Scenarios.

    Science.gov (United States)

    Dong, Feihong; Li, Hongjun; Gong, Xiangwu; Liu, Quan; Wang, Jingchao

    2015-09-03

    A typical application scenario of remote wireless sensor networks (WSNs) is identified as an emergency scenario. One of the greatest design challenges for communications in emergency scenarios is energy-efficient transmission, due to scarce electrical energy in large-scale natural and man-made disasters. Integrated high altitude platform (HAP)/satellite networks are expected to optimally meet emergency communication requirements. In this paper, a novel integrated HAP/satellite (IHS) architecture is proposed, and three segments of the architecture are investigated in detail. The concept of link-state advertisement (LSA) is designed in a slow flat Rician fading channel. The LSA is received and processed by the terminal to estimate the link state information, which can significantly reduce the energy consumption at the terminal end. Furthermore, the transmission power requirements of the HAPs and terminals are derived using the gradient descent and differential equation methods. The energy consumption is modeled at both the source and system level. An innovative and adaptive algorithm is given for the energy-efficient path selection. The simulation results validate the effectiveness of the proposed adaptive algorithm. It is shown that the proposed adaptive algorithm can significantly improve energy efficiency when combined with the LSA and the energy consumption estimation.

  12. Energy-Efficient Transmissions for Remote Wireless Sensor Networks: An Integrated HAP/Satellite Architecture for Emergency Scenarios

    Directory of Open Access Journals (Sweden)

    Feihong Dong

    2015-09-01

    Full Text Available A typical application scenario of remote wireless sensor networks (WSNs is identified as an emergency scenario. One of the greatest design challenges for communications in emergency scenarios is energy-efficient transmission, due to scarce electrical energy in large-scale natural and man-made disasters. Integrated high altitude platform (HAP/satellite networks are expected to optimally meet emergency communication requirements. In this paper, a novel integrated HAP/satellite (IHS architecture is proposed, and three segments of the architecture are investigated in detail. The concept of link-state advertisement (LSA is designed in a slow flat Rician fading channel. The LSA is received and processed by the terminal to estimate the link state information, which can significantly reduce the energy consumption at the terminal end. Furthermore, the transmission power requirements of the HAPs and terminals are derived using the gradient descent and differential equation methods. The energy consumption is modeled at both the source and system level. An innovative and adaptive algorithm is given for the energy-efficient path selection. The simulation results validate the effectiveness of the proposed adaptive algorithm. It is shown that the proposed adaptive algorithm can significantly improve energy efficiency when combined with the LSA and the energy consumption estimation.

  13. New online ecology of adversarial aggregates: ISIS and beyond.

    Science.gov (United States)

    Johnson, N F; Zheng, M; Vorobyeva, Y; Gabriel, A; Qi, H; Velasquez, N; Manrique, P; Johnson, D; Restrepo, E; Song, C; Wuchty, S

    2016-06-17

    Support for an extremist entity such as Islamic State (ISIS) somehow manages to survive globally online despite considerable external pressure and may ultimately inspire acts by individuals having no history of extremism, membership in a terrorist faction, or direct links to leadership. Examining longitudinal records of online activity, we uncovered an ecology evolving on a daily time scale that drives online support, and we provide a mathematical theory that describes it. The ecology features self-organized aggregates (ad hoc groups formed via linkage to a Facebook page or analog) that proliferate preceding the onset of recent real-world campaigns and adopt novel adaptive mechanisms to enhance their survival. One of the predictions is that development of large, potentially potent pro-ISIS aggregates can be thwarted by targeting smaller ones.

  14. On Optimization Control Parameters in an Adaptive Error-Control Scheme in Satellite Networks

    Directory of Open Access Journals (Sweden)

    Ranko Vojinović

    2011-09-01

    Full Text Available This paper presents a method for optimization of control parameters of an adaptive GBN scheme in error-prone satellite channel. Method is based on the channel model with three state, where channel have the variable noise level.

  15. Link Performance Analysis for a Proposed Future Architecture of the Air Force Satellite Control Network

    Science.gov (United States)

    2011-12-01

    data to update the known location of their spacecraft. This, of course , differs from the way STK and, in turn, the AFSCN LP obtains spacecraft...Dynamic System - A Divide and Conquer Approach. Espoo, Finland: IEEE. Cuevas, E. G., & Rehwinkel, C. A. SPOCS : A System to Measure Satellite Link

  16. Combined Geometric and Neural Network Approach to Generic Fault Diagnosis in Satellite Reaction Wheels

    DEFF Research Database (Denmark)

    Baldi, P.; Blanke, Mogens; Castaldi, P.

    2015-01-01

    This paper suggests a novel diagnosis scheme for detection, isolation and estimation of faults affecting satellite reaction wheels. Both spin rate measurements and actuation torque defects are dealt with. The proposed system consists of a fault detection and isolation module composed by a bank...

  17. ISIS Facility – Past achievements and future prospects

    Indian Academy of Sciences (India)

    Uschi Steigenberger

    2008-11-01

    The current status of the ISIS Pulsed Neutron and Muon Facility will be described covering operations and developments. Construction of a second target station was approved in 2004 including funding for the first seven neutron scattering instruments. Progress with the second target station project will be reviewed and updates on the design status of the seven `Day One' instruments, as well as plans for the next phase of the instrumentation will be presented.

  18. Particle Identification in the NIMROD-ISiS Detector Array

    CERN Document Server

    Wuenschel, S; May, L W; Wada, R; Yennello, S J

    2009-01-01

    Interest in the influence of the neutron-to-proton (N/Z) ratio on multifragmenting nuclei has demanded an improvement in the capabilities of multi-detector arrays as well as the companion analysis methods. The particle identification method used in the NIMROD-ISiS 4 $\\pi$ array is described. Performance of the detectors and the analysis method are presented for the reaction of 86Kr+64Ni at 35MeV/u.

  19. A feed-forward Hopfield neural network algorithm (FHNNA) with a colour satellite image for water quality mapping

    Science.gov (United States)

    Asal Kzar, Ahmed; Mat Jafri, M. Z.; Hwee San, Lim; Al-Zuky, Ali A.; Mutter, Kussay N.; Hassan Al-Saleh, Anwar

    2016-06-01

    There are many techniques that have been given for water quality problem, but the remote sensing techniques have proven their success, especially when the artificial neural networks are used as mathematical models with these techniques. Hopfield neural network is one type of artificial neural networks which is common, fast, simple, and efficient, but it when it deals with images that have more than two colours such as remote sensing images. This work has attempted to solve this problem via modifying the network that deals with colour remote sensing images for water quality mapping. A Feed-forward Hopfield Neural Network Algorithm (FHNNA) was modified and used with a satellite colour image from type of Thailand earth observation system (THEOS) for TSS mapping in the Penang strait, Malaysia, through the classification of TSS concentrations. The new algorithm is based essentially on three modifications: using HNN as feed-forward network, considering the weights of bitplanes, and non-self-architecture or zero diagonal of weight matrix, in addition, it depends on a validation data. The achieved map was colour-coded for visual interpretation. The efficiency of the new algorithm has found out by the higher correlation coefficient (R=0.979) and the lower root mean square error (RMSE=4.301) between the validation data that were divided into two groups. One used for the algorithm and the other used for validating the results. The comparison was with the minimum distance classifier. Therefore, TSS mapping of polluted water in Penang strait, Malaysia, can be performed using FHNNA with remote sensing technique (THEOS). It is a new and useful application of HNN, so it is a new model with remote sensing techniques for water quality mapping which is considered important environmental problem.

  20. Masithethe: speech and language development and difficulties in isiXhosa.

    Science.gov (United States)

    Pascoe, Michelle; Smouse, Mantoa

    2012-03-02

    IsiXhosa is the second most spoken language in South Africa and one of its official languages. Spoken mainly in the Eastern and Western Cape regions it is fitting that much of the research focusing on children's isiXhosa speech and language acquisition has been carried out at the University of Cape Town (UCT). We describe what is known about children's acquisition of isiXhosa, and highlight studies which inform our knowledge of the typical development of the language in relation to the acquisition of consonants including clicks and the isiXhosa noun class system. Little is known about the specific nature of speech and language difficulties in isiXhosa, and the development of isiXhosa resources for speech and language assessment and therapy is in its infancy. Suggestions are made for advancing knowledge and practice which is needed to provide a relevant and quality service to isiXhosa speakers.

  1. Dynamic Channel Network Extraction from Satellite Imagery of the Jamuna River

    Science.gov (United States)

    Addink, E. A.; Marra, W. A.; Kleinhans, M. G.

    2010-12-01

    Evolution of the largest rivers on Earth is poorly understood while their response to global change is dramatic, such as severe drought and flooding problems. Rivers with high annual dynamics, like the Jamuna, allow us to study their response to changing conditions. Most remote-sensing work so far focused only on pixel-based analysis of channels and change detection or manual digitisation of channels, which is far from urgently needed quantifiers of pattern and pattern change. Using a series of Landsat TM images taken at irregular intervals showing inter- and intra-annual variation, we demonstrate that braided rivers can be represented as nearly chain-like directional networks. These can be studied with novel methods gleaned from neurology. These networks provide an integral spatial description of the network and should not be confused with hierarchical hydrological stream network descriptions developed in the ’60s to describe drainage basins. The images were first classified into water, bare sediment and vegetation. The contiguous water body of the river was then selected and translated into a network description with bifurcations and confluences at the nodes, and interconnecting channels. Along the entire river the well-known braiding indices were derived from the network. The channel width is a crucial attribute of the channel network as this allows the calculation of bifurcation asymmetry. The width was also used with channel length as weights to all the elements in the network in the calculation of more advanced measures for the nature and evolution of the channel network. The key step here is to describe river network evolution by identifying the same node in multiple subsequent images as well as new and abandoned nodes, in order to distinguish migration of bifurcations from avulsion processes. Once identified through time, the changes in node position and the changes in the connected channels can be quantified. These changes can potentially be linked to

  2. Rainfall measurements from cellular networks microwave links : an alternative ground reference for satellite validation and hydrology in Africa .

    Science.gov (United States)

    Gosset, Marielle; cazenave, frederic; Zougmore, françois; Doumounia, Ali; kacou, Modeste

    2015-04-01

    In many part of the Tropics the ground based gauge networks are sparse, often degrading and accessing this data for monitoring rainfall or for validating satellite products is sometime difficult. Here, an alternative rainfall measuring technique is proposed and tested in West Africa. It is based on using commercial microwave links from cellular telephone networks to detect and quantify rainfall. Rainfall monitoring based on commercial terrestrial microwave links has been tested for the first time in Burkina Faso, in Sahel. The rainfall regime is characterized by intense rainfall intensities brought by mesoscale Convective systems (MCS), generated by deep organized convection. The region is subjected to drought as well as dramatic floods associated with the intense rainfall provided by a few MCSs. The hydrometeorological risk is increasing and need to be monitored. In collaboration with the national cellular phone operator, Telecel Faso, the attenuation on 29 km long microwave links operating at 7 GHz was monitored at 1s time rate for the monsoon season 2012. The time series of attenuation is transformed into rain rates and compared with rain gauge data. The method is successful in quantifying rainfall: 95% of the rainy days are detected. The correlation with the daily raingauge series is 0.8 and the season bias is 5%. The correlation at the 5 min time step within each event is also high. We will present the quantitative results, discuss the uncertainties and compare the time series and the 2D maps with those derived from a polarimetric radar. The results demonstrate the potential interest of exploiting national and regional wireless telecommunication networks to provide rainfall maps for various applications : urban hydrology, agro-hydrological risk monitoring, satellite validation and development of combined rainfall products. We will also present the outcome of the first international Rain Cell Africa workshop held in Ouagadougou early 2015.

  3. Improving information dissemination in sparse vehicular networks by adding satellite communication

    NARCIS (Netherlands)

    Kloiber, Bernhard; Strang, Thomas; Spijker, Hanno; Heijenk, Geert

    2012-01-01

    Information dissemination in pure Vehicular Ad Hoc NETworks (VANETs) such as ITS-G5 becomes problematic when the network is sparse. In situations where the number of vehicles, that can act as a communication node, is insufficiently low, e.g. in rural areas, during night-time or because of a low mark

  4. Improving information dissemination in sparse vehicular networks by adding satellite communication

    NARCIS (Netherlands)

    Kloiber, Bernhard; Strang, Thomas; Spijker, Hanno; Heijenk, Geert

    Information dissemination in pure Vehicular Ad Hoc NETworks (VANETs) such as ITS-G5 becomes problematic when the network is sparse. In situations where the number of vehicles, that can act as a communication node, is insufficiently low, e.g. in rural areas, during night-time or because of a low

  5. 卫星宽带网络系统的研究与分析%An Analytical Research on Satellite Broadband Network system

    Institute of Scientific and Technical Information of China (English)

    薛中伟

    2012-01-01

    This artical mainly introduces the satellite broadband network system basic principle,technical features, development status and trend of application, through the research and analysis,that the satellite broadband network will be widely used in information communication.%本文主要介绍了卫星宽带网络系统的基本原理、技术特点、发展现状和应用趋势,通过研究和分析,证明了卫星宽带网络在信息通信领域具有广阔的应用前景。

  6. An advanced OBP-based payload operating in an asynchronous network for future data relay satellites utilising CCSDS-standard data structures

    Science.gov (United States)

    Grant, M.; Vernucci, A.

    1991-01-01

    A possible Data Relay Satellite System (DRSS) topology and network architecture is introduced. An asynchronous network concept, whereby each link (Inter-orbit, Inter-satellite, Feeder) is allowed to operate on its own clock, without causing loss of information, in conjunction with packet data structures, such as those specified by the CCSDS for advanced orbiting systems is discussed. A matching OBP payload architecture is described, highlighting the advantages provided by the OBP-based concept and then giving some indications on the OBP mass/power requirements.

  7. Load-Aware Radio Access Selection in Future Generation Satellite-Terrestrial Wireless Networks

    Directory of Open Access Journals (Sweden)

    M. Ali

    2012-03-01

    Full Text Available In the telecommunication networks the introduction of Next Generation Wireless Networks (NGWN has been described as the most significant change in wireless communication. The convergence of different access networks in NGWN allows generalized mobility, consistency and ubiquitous provision of services to mobile users. The general target of NGWN is to transport different types of information like voice,data, and other media like video in packets form like IP. The NGWNs offer significant savings in costs to the operators along with new and interesting services to the consumers. Major challenges in NGWN are efficient resource utilization, maintaining service quality, reliability and the security. This paper proposes a solution for seamless load aware Radio Access Technology (RAT selection based on interworking of different RATs in NGWN. In this paper novel load balancing algorithms have been proposed which have been simulated on the target network architecture for TCP data services. The IEEE 802.21 Media Independent Handover (MIH is utilized in load balancing specifically for mobility management, which enable low handover latency by reducing the target network detection time. The proposed method considers the network type, signal strength, data rate and network load as primary decision parameters for RAT selection process and consists of two different algorithms, one located inthe mobile terminal and the other at the network side. The network architecture, the proposed load balancing framework and RAT selection algorithms were simulated using NS2. Different attributes like load distribution in the wireless networks and average throughput to evaluate the effects of load balancing in considered scenarios.

  8. Destination directed packet switch architecture for a geostationary communication satellite network

    Science.gov (United States)

    Ivancic, W. D.; Shalkhauser, M. J.; Bobinsky, E. A.; Soni, N. J.; Quintana, J. A.; Kim, H.; Wagner, P.; Vanderaar, M.

    1992-01-01

    A major effort at NASA/Lewis is to identify and develop critical digital technologies and components that enable new commercial missions or significantly improve the performance, cost efficiency, and/or reliability of existing and planned space comunications systems. NASA envisions the need for low data rate, direct to the user communications services, for data, facsimile, voice, and video conferencing. A report that focuses on destination directed packet switching architectures for geostationary communication satellites is presented.

  9. Destination directed packet switch architecture for a geostationary communication satellite network

    Science.gov (United States)

    Ivancic, W. D.; Shalkhauser, M. J.; Bobinsky, E. A.; Soni, N. J.; Quintana, J. A.; Kim, H.; Wagner, P.; Vanderaar, M.

    1992-08-01

    A major effort at NASA/Lewis is to identify and develop critical digital technologies and components that enable new commercial missions or significantly improve the performance, cost efficiency, and/or reliability of existing and planned space comunications systems. NASA envisions the need for low data rate, direct to the user communications services, for data, facsimile, voice, and video conferencing. A report that focuses on destination directed packet switching architectures for geostationary communication satellites is presented.

  10. Combined Geometric and Neural Network Approach to Generic Fault Diagnosis in Satellite Actuators and Sensors

    OpenAIRE

    Baldi, Pietro; Blanke, Mogens; Castaldi, Paolo; Mimmo, Nicola; Simani, Silvio

    2016-01-01

    This paper suggests a novel diagnosis scheme for detection, isolation and estimation of faults affecting satellite reaction wheels. Both spin rate measurements and actuation torque defects are dealt with. The proposed system consists of a fault detection and isolation module composed by a bank of residual filters organized in a generalized scheme, followed by a fault estimation module consisting of a bank of adaptive estimation filters. The residuals are decoupled from aerodynamic disturbance...

  11. Satellite Remote Sensing with Artificial Neural Network Modeling Techniques for Water Quality Monitoring

    Science.gov (United States)

    Kuo, Y. C.; Chen, C. F.

    2016-12-01

    The analyzed parameters of the water quality samples in Lake Nicaragua and Lake Managua include basic physical and chemical water quality parameters, nutrients, bacteria and zooplankton index, heavy metals and organic compounds in the sediments etc. 5 parameters are tested to assess lake eutrophication. To associate with satellite data, the analysis is aim to establish a set of mathematical transformations to convert the model spectra of satellite imagery reactions on water quality parameters and further to calculate the concentration of the parameters in both lakes. The sampling period took place during the rainy season. The high cloud-covered satellite imagery did not provide a completed available data for the analysis. Therefore, we used mathematical techniques to remake an image which contains a completed lake areas. Following by using linear equation to build the water quality models, the results suggested that the testing of chlorophyll in the model performance was the most accurate, and then the suspended solids, total phosphorus and total nitrogen. Fecal colon bacilli, of all parameters, has the worst performance in testing accuracy.

  12. Getting into networks and clusters: evidence from the Midi-Pyrenean Global Navigation Satellite Systems (GNSS) Collaboration Network

    NARCIS (Netherlands)

    Vicente, J.; Balland, P.M.A.; Brossard, O.

    2011-01-01

    This paper analyses clusters from collaborative knowledge relations. Focusing on the interface of clusters and networks contributes to a better understanding of collaboration, within and across places and cognitive domains. We propose an empirical analysis of the Midi-Pyrenean GNSS (Global Navigatio

  13. Blind Multiuser Receivers for ISI CDMA Channels Using the ε-Approximation Algorithms

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The problem of the blind demodulation of multiuser information symbols in a high-rate Code Division Multiple Access (CDMA) network in the presence of InterSymbol Interference (ISI) is of considerable interest. The dispersive CDMA channel is first cast into a Multiple-Input Multiple-Out (MIMO) signal model framework. Then, the problem of the blind channel equalization and multiuser detection is considered. In this paper, we formulate the problem of blind channel estimation and signal detection into a quadratic programming with binary constraints. Then, the efficient ε-approximation algorithms are presented and applied to find the solution to the quadratic programming. The proposed approach does not estimate the channel directly or rely on any statistics. Simulation results support our theoretical analysis.

  14. LEO星座网络动态源路由算法%Dynamic Source Routing Algorithm for LEO Satellite Networks

    Institute of Scientific and Technical Information of China (English)

    万鹏; 曹志刚; 王京林

    2007-01-01

    近年来,在低轨(LEO)卫星星座通信网络中采用网际协议(IP)路由算法的研究已经取得了一系列进展,文章论述了LEO星座通信网络的特点、拓扑结构和虚拟节点策略.在此基础上提出了基于泛洪路由的LEO星座动态源路由算法DSR-LSN(Dynamic Source Routing algorithm in LEO Satellite Networks),星座网络仿真表明,DSR-LSN算法具有网络路由状态稳定性好、时延小的优点.

  15. Performance Analysis of Anti-Interference Wireless Packet Networks for LEO Micro-Satellite with Adaptive Nulling Antenna Array

    Institute of Scientific and Technical Information of China (English)

    LIU Hai-tao; HAN Fang-jing; WAN Jian-wei

    2006-01-01

    Information integrity is key to successful operations in intricacy environments in the future, especially when strong interferences exist. This paper presents the design of a novel wireless packet network receiver system for Low Earth Orbit (LEO) micro-satellites with adaptive nulling antenna arrays. It uses three types of interference suppression in cascade: namely spread spectrum, adaptive array nulling, and transform domain filtering. This paper proposes a pilot channel-aided method in order to make full advantage of this arrangement, and analyzes its throughput and delay performance using the Markov chain model. Our results show that this method can achieve excellent delay and throughput performance: When the number of array antenna is 8, its throughput increase relative to the standard Slot-ALOHA protocol is 125 %.

  16. Maritime Aerosol Network as a Component of AERONET - First Results and Comparison with Global Aerosol Models and Satellite Retrievals

    Science.gov (United States)

    Smirnov, A.; Holben, B. N.; Giles, D. M.; Slutsker, I.; O'Neill, N. T.; Eck, T. F.; Macke, A.; Croot, P.; Courcoux, Y.; Sakerin, S. M.; Smyth, T. J.; Zielinski, T.; Zibordi, G.; Goes, J. I.; Harvey, M. J.; Quinn, P. K.; Nelson, N. B.; Radionov, V. F.; Duarte, C. M.; Remer, L. A.; Kahn, R. A.; Kleidman, R. G.; Gaitley, B. J.; Tan, Q.; Diehl, T. L.

    2011-01-01

    The Maritime Aerosol Network (MAN) has been collecting data over the oceans since November 2006. Over 80 cruises were completed through early 2010 with deployments continuing. Measurement areas included various parts of the Atlantic Ocean, the Northern and Southern Pacific Ocean, the South Indian Ocean, the Southern Ocean, the Arctic Ocean and inland seas. MAN deploys Microtops handheld sunphotometers and utilizes a calibration procedure and data processing traceable to AERONET. Data collection included areas that previously had no aerosol optical depth (AOD) coverage at all, particularly vast areas of the Southern Ocean. The MAN data archive provides a valuable resource for aerosol studies in maritime environments. In the current paper we present results of AOD measurements over the oceans, and make a comparison with satellite AOD retrievals and model simulations.

  17. An implementation of Software Defined Radios for federated aerospace networks: Informing satellite implementations using an inter-balloon communications experiment

    Science.gov (United States)

    Akhtyamov, Rustam; Cruz, Ignasi Lluch i.; Matevosyan, Hripsime; Knoll, Dominik; Pica, Udrivolf; Lisi, Marco; Golkar, Alessandro

    2016-06-01

    Novel space mission concepts such as Federated Satellite Systems promise to enhance sustainability, robustness, and reliability of current missions by means of in-orbit sharing of space assets. This new paradigm requires the utilization of several technologies in order to confer flexibility and re-configurability to communications systems among heterogeneous spacecrafts. This paper illustrates the results of the experimental demonstration of the value proposition of federated satellites through two stratospheric balloons interoperating with a tracking ground station through Commercial Off-The-Shelf Software Defined Radios (SDRs). The paper reports telemetry analysis and characterizes the communications network that was realized in-flight. Furthermore, it provides details on an in-flight anomaly experienced by one of the balloons, which was recovered through the use of the federated technology that has been developed. The anomaly experienced led to the early loss of the directional link from the ground station to the affected stratospheric balloon node after 15 min in flight. Nevertheless, thanks to the federated approach among the systems, the ground station was still able to retrieve the balloon's data in real time through the network system, for which the other balloon operated as a federated relay for 45 min in flight, uninterrupted. In other words, the federated approach to the system allowed triplicating the useful lifetime of the defective system, which would have not been possible to realize otherwise. Such anomaly coincidentally demonstrated the value of the federated approach to space systems design. The paper paves the way for future tests on space assets.

  18. Research progress of Group Key Management for Multi-layered Satellite Networks%多层卫星网络组密钥管理研究进展

    Institute of Scientific and Technical Information of China (English)

    余哲赋; 周海刚; 吴兆峰; 朱晓薇

    2012-01-01

    为保证多层卫星网络的通信安全,使用组密钥对通信进行加密是一个普遍而有效的方法。设计适合卫星网络的组密钥管理方案,是确保卫星通信安全的关键问题之一。本文介绍了多层卫星网络的概况,对现有多层卫星网络组密钥管理方案进行了分类,详细分析了几类典型的组密钥管理方案,指出了存在的问题,并对以后的研究方向作了展望。%Encrypting the contents of communication by using group key is an universal and effective method to ensure the security of communication in the Multi-layered satellite networks,and the design of a group key management scheme suitable for satellite networks is one of the key problems.This article provides an introduction of multi-layered satellite networks and classifies the routing protocols.This paper details several existing typical group key management schemes,and points out the corresponding disadvantages.The trends of group key management for multi-layered satellite networks are analyzed briefly.

  19. The ISI (Information Sciences Institute) Experimental Multimedia Mail System.

    Science.gov (United States)

    1986-09-01

    AD-R173 288 THE IS! ( INFORMATION SCIENCES INSTITUTE) EXPERIMENTAL 1/1NULTIHEDIA MAIL SVSTEM(U) INFORMATION SCI NC S INS MARINA DEL REY CA J B POSTEL...ORGANIZATION USC/ Information Sciences Institute (If applicable) 6c. ADDRESS (City, State, and ZIP Code) 7b. ADDRESS (City, State, and ZIP Code) 4676...Codes a1tnd/or D l .-:zi INFORMATION SCIENCES INSTITUTE 213/I’?2-I1511 Thrsac sspotdby the Dees dacdRsac rjcAgency une otatN VD 18 35Views ISI

  20. Defeating ISIS by Winning the War of Ideas

    Science.gov (United States)

    2017-03-17

    Abu Musab al-Zarqawi grew up in Jordan in an environment with abject poverty and high unemployment rate.8 The social and material environment shaped...term panacea. There is no simple way to undo years of radical religious education nor overcome damage done by 26 years of U.S. led war in the...propaganda and cyber-attacks against radical ISIS messaging. As Gerges has identified, “ISIS’s weakest link is its poverty of ideas,” and the U.S. must

  1. Java Image I/O for VICAR, PDS, and ISIS

    Science.gov (United States)

    Deen, Robert G.; Levoe, Steven R.

    2011-01-01

    This library, written in Java, supports input and output of images and metadata (labels) in the VICAR, PDS image, and ISIS-2 and ISIS-3 file formats. Three levels of access exist. The first level comprises the low-level, direct access to the file. This allows an application to read and write specific image tiles, lines, or pixels and to manipulate the label data directly. This layer is analogous to the C-language "VICAR Run-Time Library" (RTL), which is the image I/O library for the (C/C++/Fortran) VICAR image processing system from JPL MIPL (Multimission Image Processing Lab). This low-level library can also be used to read and write labeled, uncompressed images stored in formats similar to VICAR, such as ISIS-2 and -3, and a subset of PDS (image format). The second level of access involves two codecs based on Java Advanced Imaging (JAI) to provide access to VICAR and PDS images in a file-format-independent manner. JAI is supplied by Sun Microsystems as an extension to desktop Java, and has a number of codecs for formats such as GIF, TIFF, JPEG, etc. Although Sun has deprecated the codec mechanism (replaced by IIO), it is still used in many places. The VICAR and PDS codecs allow any program written using the JAI codec spec to use VICAR or PDS images automatically, with no specific knowledge of the VICAR or PDS formats. Support for metadata (labels) is included, but is format-dependent. The PDS codec, when processing PDS images with an embedded VIAR label ("dual-labeled images," such as used for MER), presents the VICAR label in a new way that is compatible with the VICAR codec. The third level of access involves VICAR, PDS, and ISIS Image I/O plugins. The Java core includes an "Image I/O" (IIO) package that is similar in concept to the JAI codec, but is newer and more capable. Applications written to the IIO specification can use any image format for which a plug-in exists, with no specific knowledge of the format itself.

  2. Information System Constraint Language (ISyCL) Technical Report

    Science.gov (United States)

    1992-09-01

    Mayer 871, and IDEFIx [DACOM 85], since there is no need to repeat here the information in those excellent texts. ISyCL Technical Report 5 Final...structures used to dc.sciihc ,owntraints on an IDEF3 process description would he different than tthose used to add con-sLraints to an IDEFIx data model...probably using tags and other user-supplied aids. For example, an IDEFI entity class might map to an IDEFIx entity, but the modeler would have to

  3. A new generic method for the semi-automatic extraction of river and road networks in low and mid-resolution satellite images

    Energy Technology Data Exchange (ETDEWEB)

    Grazzini, Jacopo [Los Alamos National Laboratory; Dillard, Scott [PNNL; Soille, Pierre [EC JRC

    2010-10-21

    This paper addresses the problem of semi-automatic extraction of road or hydrographic networks in satellite images. For that purpose, we propose an approach combining concepts arising from mathematical morphology and hydrology. The method exploits both geometrical and topological characteristics of rivers/roads and their tributaries in order to reconstruct the complete networks. It assumes that the images satisfy the following two general assumptions, which are the minimum conditions for a road/river network to be identifiable and are usually verified in low- to mid-resolution satellite images: (i) visual constraint: most pixels composing the network have similar spectral signature that is distinguishable from most of the surrounding areas; (ii) geometric constraint: a line is a region that is relatively long and narrow, compared with other objects in the image. While this approach fully exploits local (roads/rivers are modeled as elongated regions with a smooth spectral signature in the image and a maximum width) and global (they are structured like a tree) characteristics of the networks, further directional information about the image structures is incorporated. Namely, an appropriate anisotropic metric is designed by using both the characteristic features of the target network and the eigen-decomposition of the gradient structure tensor of the image. Following, the geodesic propagation from a given network seed with this metric is combined with hydrological operators for overland flow simulation to extract the paths which contain most line evidence and identify them with the target network.

  4. Self-Assembled Core-Satellite Gold Nanoparticle Networks for Ultrasensitive Detection of Chiral Molecules by Recognition Tunneling Current.

    Science.gov (United States)

    Zhang, Yuanchao; Liu, Jingquan; Li, Da; Dai, Xing; Yan, Fuhua; Conlan, Xavier A; Zhou, Ruhong; Barrow, Colin J; He, Jin; Wang, Xin; Yang, Wenrong

    2016-05-24

    Chirality sensing is a very challenging task. Here, we report a method for ultrasensitive detection of chiral molecule l/d-carnitine based on changes in the recognition tunneling current across self-assembled core-satellite gold nanoparticle (GNP) networks. The recognition tunneling technique has been demonstrated to work at the single molecule level where the binding between the reader molecules and the analytes in a nanojunction. This process was observed to generate a unique and sensitive change in tunneling current, which can be used to identify the analytes of interest. The molecular recognition mechanism between amino acid l-cysteine and l/d-carnitine has been studied with the aid of SERS. The different binding strength between homo- or heterochiral pairs can be effectively probed by the copper ion replacement fracture. The device resistance was measured before and after the sequential exposures to l/d-carnitine and copper ions. The normalized resistance change was found to be extremely sensitive to the chirality of carnitine molecule. The results suggested that a GNP networks device optimized for recognition tunneling was successfully built and that such a device can be used for ultrasensitive detection of chiral molecules.

  5. The ISI distribution of the stochastic Hodgkin-Huxley neuron.

    Science.gov (United States)

    Rowat, Peter F; Greenwood, Priscilla E

    2014-01-01

    The simulation of ion-channel noise has an important role in computational neuroscience. In recent years several approximate methods of carrying out this simulation have been published, based on stochastic differential equations, and all giving slightly different results. The obvious, and essential, question is: which method is the most accurate and which is most computationally efficient? Here we make a contribution to the answer. We compare interspike interval histograms from simulated data using four different approximate stochastic differential equation (SDE) models of the stochastic Hodgkin-Huxley neuron, as well as the exact Markov chain model simulated by the Gillespie algorithm. One of the recent SDE models is the same as the Kurtz approximation first published in 1978. All the models considered give similar ISI histograms over a wide range of deterministic and stochastic input. Three features of these histograms are an initial peak, followed by one or more bumps, and then an exponential tail. We explore how these features depend on deterministic input and on level of channel noise, and explain the results using the stochastic dynamics of the model. We conclude with a rough ranking of the four SDE models with respect to the similarity of their ISI histograms to the histogram of the exact Markov chain model.

  6. Electron cloud observations at the ISIS Proton Synchrotron

    CERN Document Server

    Pertica, A

    2013-01-01

    The build up of electron clouds inside a particle accelerator vacuum chamber can produce strong transverse and longitudinal beam instabilities which in turn can lead to high levels of beam loss often requiring the accelerator to be run below its design specification. To study the behaviour of electron clouds at the ISIS Proton Synchrotron, a Micro-Channel Plate (MCP) based electron cloud detector has been developed. The detector is based on the Retarding Field Analyser (RFA) design and consists of a retarding grid, which allows energy analysis of the electron signal, and a MCP assembly placed in front of the collector plate. The MCP assembly provides a current gain over the range 300 to 25K, thereby increasing the signal to noise ratio and dynamic range of the measurements. This paper presents the first electron cloud observations at the ISIS Proton Synchrotron. These results are compared against signals from a beam position monitor and a fast beam loss monitor installed at the same location.

  7. Handbook of satellite applications

    CERN Document Server

    Madry, Scott; Camacho-Lara, Sergio

    2017-01-01

    The first edition of this ground breaking reference work was the most comprehensive reference source available about the key aspects of the satellite applications field. This updated second edition covers the technology, the markets, applications and regulations related to satellite telecommunications, broadcasting and networking—including civilian and military systems; precise satellite navigation and timing networks (i.e. GPS and others); remote sensing and meteorological satellite systems. Created under the auspices of the International Space University based in France, this brand new edition is now expanded to cover new innovative small satellite constellations, new commercial launching systems, innovation in military application satellites and their acquisition, updated appendices, a useful glossary and more.

  8. Design of Geodetic SVLBI Satellite Orbit and Its Tracking Network%SVLBI用于大地测量的卫星轨道及其跟踪网设计

    Institute of Scientific and Technical Information of China (English)

    魏二虎; 刘经南; KULKARNI M.N.; FREY Sándor

    2008-01-01

    SVLBI (space very long baseline interferometry) has some important potential applications in geodesy and geodynam- ics, for which one of the most difficult tasks is to precisely determine the orbit of an SVLBI satellite. This work studies several technologies that will possibly be able to determine the orbit of a space VLBI satellite. Then, according to the types and charac- teristics of the satellite and the requirements for geodetic study and the geometry of the GNSS (GPS, GALILEO) satellite to track the space VLBI satellite, the six Keplerian elements of the SVLBI satellite (TEST-SVLBI) are determined. A program is designed to analyze the coverage area of space of different altitudes by the stations of the network, with which the tracking network of TEST-SVLBI is designed. The efficiency of tracking TEST-SVLBI by the network is studied, and the results are presented.

  9. 移动卫星网络中卫星切换调度研究%Research on the Handover Scheduling in Mobile Satellite Communication Networks

    Institute of Scientific and Technical Information of China (English)

    吴兆峰; 胡谷雨; 金凤林

    2015-01-01

    针对卫星切换调度问题,提出了一种最大服务时长切换调度算法。该算法利用了现有的GPS基础设施和卫星网络中卫星的多样性(即在任意时刻多颗卫星覆盖相同的区域),减少了用户在通信过程中的切换次数,从而最终降低了用户的掉话率,实现了用户在低轨( LEO)卫星网络中实时高效的切换。在Iridium卫星网络中的仿真结果验证了该算法的有效性。%A new satellite handover scheduling algorithm based on the maximum residual service time was proposed. The algorithm exploits both global positioning system ( GPS) infrastructure and satellite diversi-ty, providing a simple and real-time handover management in low earth orbit ( LEO) satellite networks to minimize the expected number of satellite handovers. It reduces the users' call drop probability ultimate-ly. Simulations were carried out on the typical Iridium satellite network and the simulation results corrob-orate the advantages gained by the proposed algorithm.

  10. Method of Performance-Aware Security of Unicast Communication in Hybrid Satellite Networks

    Science.gov (United States)

    Roy-Chowdhury, Ayan (Inventor); Baras, John S. (Inventor)

    2014-01-01

    A method and apparatus utilizes Layered IPSEC (LES) protocol as an alternative to IPSEC for network-layer security including a modification to the Internet Key Exchange protocol. For application-level security of web browsing with acceptable end-to-end delay, the Dual-mode SSL protocol (DSSL) is used instead of SSL. The LES and DSSL protocols achieve desired end-to-end communication security while allowing the TCP and HTTP proxy servers to function correctly.

  11. A global network for the control of snail-borne disease using satellite surveillance and geographic information systems.

    Science.gov (United States)

    Malone, J B; Bergquist, N R; Huh, O K; Bavia, M E; Bernardi, M; El Bahy, M M; Fuentes, M V; Kristensen, T K; McCarroll, J C; Yilma, J M; Zhou, X N

    2001-04-27

    At a team residency sponsored by the Rockefeller Foundation in Bellagio, Italy, 10-14 April 2000 an organizational plan was conceived to create a global network of collaborating health workers and earth scientists dedicated to the development of computer-based models that can be used for improved control programs for schistosomiasis and other snail-borne diseases of medical and veterinary importance. The models will be assembled using GIS methods, global climate model data, sensor data from earth observing satellites, disease prevalence data, the distribution and abundance of snail hosts, and digital maps of key environmental factors that affect development and propagation of snail-borne disease agents. A work plan was developed for research collaboration and data sharing, recruitment of new contributing researchers, and means of access of other medical scientists and national control program managers to GIS models that may be used for more effective control of snail-borne disease. Agreement was reached on the use of compatible GIS formats, software, methods and data resources, including the definition of a 'minimum medical database' to enable seamless incorporation of results from each regional GIS project into a global model. The collaboration plan calls for linking a 'central resource group' at the World Health Organization, the Food and Agriculture Organization, Louisiana State University and the Danish Bilharziasis Laboratory with regional GIS networks to be initiated in Eastern Africa, Southern Africa, West Africa, Latin America and Southern Asia. An Internet site, www.gnosisGIS.org, (GIS Network On Snail-borne Infections with special reference to Schistosomiasis), has been initiated to allow interaction of team members as a 'virtual research group'. When completed, the site will point users to a toolbox of common resources resident on computers at member organizations, provide assistance on routine use of GIS health maps in selected national disease control

  12. Routing Technology Research for LEO Satellite Constellation Networks%低轨道卫星星座网络路由研究

    Institute of Scientific and Technical Information of China (English)

    蒋文娟; 宗鹏

    2011-01-01

    Because of the particular features of LEO satellite networks, such as dynamic topology, non-homogeneous traffic distribution,limited power and processing, new satellite routing approaches should be developed. How to design simple and efficient routing algorithm becomes the hot topic of LEO satellite networks. Analyze the characteristics of LEO satellite networks, and then survey the cunrrent LEO satellite routing algorithms classified with the geometric model, handoff and onboard processing capability. Typical algorithms of each class are presented and their advantages, suitable environment and shortcomings with a detailed comprehensive comparison are discussed. The end of the paper points out the future research field for LFO satellite routing prob1em.%拓扑时变性、承载业务分布不均衡以及星上资源有限,使得设计新的低轨道卫星星座网络路由算法迫在眉睫.如何设计简单、高效的低轨道卫星星座路由成为当前卫星网络研究的热点问题.深入剖析了LEO卫星网络的特点,从几何模型、切换以及星上处理能力三个视角出发,分类综述了LEO卫星路由算法,阐述了各类路由的典型算法,讨论了每种算法的优点和适用环境,剖析了其中存在的问题,并对它们进行了综合对比.最后指出了LEO卫星路由算法进一步的研究方向.

  13. SHADOZ (Southern Hemisphere ADditional OZonesondes): An Ozonesonde Network for Satellite Validation, Climatology and Modeling

    Science.gov (United States)

    Thompson, Anne M.; Witte, Jacquelyn C.; Schmidlin, Francis J.; Oltmans, Samuel J.; McPeters, Richard D.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    In the past 5 years, new tropical ozone data products have been developed from TOMS and other satellites, During this period, global chemical-transport models have been used for ozone assessment studies. However, there has been a lack of independent ozone profiles in the tropics for evaluation of the data sets and models. In 1998, NASA's Goddard Space Flight Center, Wallops Flight Facility and NOAA's CMDL (Climate Monitoring and Diagnostics Lab), began a 2-year project to collect a consistent data set by augmenting ozonesonde launches at southern hemisphere tropical sites The measurements are available to the scientific community at a single electronic location - the SHADOZ website at NASA/Goddard: http://code9l6.gsfc.nasa.gov/Data services/Shadoz/shadoz hmpg2.html. Stations in SHADOZ include four islands in the Pacific: Fiji, Tahiti, San Cristobal (Galapagos) and American Samoa. Two sites are at and in the Atlantic: Natal (Brazil) and Ascension Island. Three other sites span Africa (Nairobi and Irene, South Africa) and the Indian Ocean (Reunion Island and Watukosek in Java, Indonesia). All SHADOZ sites are using ECC-type sondes, with the conversion from JMD sondes at Java in 1999, but there are variations in sonde preparation technique and data processing. During the 1998-1999 period, more than 550 sondes were incorporated into the SHADOZ data base. Examples from these measurements illustrate the tropical wave-one pattern in total ozone which is easily detectable by satellite. They also show that the wave-one pattern appears to be in the troposphere, as assumed in creating the modified-residual tropospheric ozone data product from TOMS. SHADOZ will add data from intensive field campaigns from time to time. Recent contributions to the SHADOZ archive are from the INDOEX (Indian Ocean Experiment January-March 1999)sondes at the Maldives (5N, 73E) and 27 sondes on the US NOAA oceanographic vessel, the FIN Ronald H Brown between Virginia (US) and Mauritius via Cape

  14. FCJ-140 Radio Feeds, Satellite Feeds, Network Feeds: Subjectivity Across the Straits of Gibraltar.

    Directory of Open Access Journals (Sweden)

    Nicholas Knouf

    2012-07-01

    Full Text Available This paper engages with the practices surrounding the two fadaiat encounters that took place simultaneously in Spain and Morocco in the summers of 2004 and 2005 (see http://fadaiat.net/ .  The fadaiat project focused on the question of immigration to Europe, specifically from northern Africa, and the ‘Fortress Europe’ responses by European Union governments.  Participants in fadaiat included academic scholars, free software developers, artists, and activists, forming a meta-network that created bridges across disparate communities and practices.  In particular, the participation of the Spanish collective hackitectura was key; they describe themselves as a ‘posse of architects, hackers and social activists experimenting in the merging territories of recombining spatial cyborgs composed by physical spaces, ICT networks and bodies’.  hackitectura led the development of both a temporary civil, non-commercial wireless link across the straits of Gibraltar between Tarifa, Spain and Tangier, Morocco, as well as an entirely free software audio/video streaming system, that enabled participants on both sides to come together independently of the restrictions normally placed on such movement by immigration laws.The importance of free software for fadaiat extends beyond its purely instrumental use as an agent for disrupting state control.  Indeed, the imagery of computation and free software – networks, links, patches, nodes, penguins – pervades the documentation of the project.  Rave parties simulcast across the straits are as important as the discussions and software produced.  I suggest that this can be understood as developing new forms of subjectivity, in the sense given by Felix Guattari, and therefore link the fadaiat project to earlier pirate radio practices, especially Radio Alice in Bologna, Italy, in which Guattari was involved.

  15. Route strategy of satellite network in GNSS based on topology evolution law

    Institute of Scientific and Technical Information of China (English)

    Xianqing Yi; Zhenwei Hou; Tao Zhong; Yaohong Zhang; Zhili Sun

    2014-01-01

    As each type of satel ite network has different link features, its data transmission must be designed based on its link features to improve the efficiency of data transferring. The transmission of navigation integrated services information (NISI) in a global navigation satel ite system (GNSS) with inter-satel ite links (ISLs) is studied by taking the real situation of inter-satel ite communication links into account. An on-demand computing and buffering centralized route strategy is proposed based on dynamic grouping and the topology evolution law of the GNSS network within which the satel ite nodes are operated in the manner of dynamic grouping. Dynamic grouping is based on satel ites spatial relationships and the group role of the satel ite node changes by turns due to its spatial relationships. The route strategy provides significant advantages of high efficiency, low complexity, and flexi-ble configuration, by which the established GNSS can possess the features and capabilities of feasible deployment, efficient trans-mission, convenient management, structural invulnerability and flexible expansion.

  16. Research on Satellite Network Secure Routing Objectives%卫星网络安全路由目标研究

    Institute of Scientific and Technical Information of China (English)

    周星; 刘军; 董春冻; 张玉静

    2013-01-01

    确定合适的安全目标是对协议进行安全增强的前提,针对目前对卫星网络路由协议的安全目标研究不充分,没有统一的安全目标的现状,文中对卫星网络路由协议的安全目标进行研究,并提出改进的安全路由目标.通过在现有plausible routing即路由可达的目标基础上对路由消息进行认证性、机密性等保护以增强安全性,并用串空间将所提目标形象地表示.分析表明,改进的安全目标,克服了原plausible routing目标的部分不足,增进了路由协议的安全性.文中提出的安全目标进一步从形式化的方式上对卫星网络路由协议的安全性进行了研究,为以后的研究提供了一定的基础.%It used to be the foremost thing to give a proper secure objectives so as to make a protocol safer,as there has been no sufficient research on secure objectives and no secure objectives is well accepted so far,researched the satellite network secure routing objectives,and gave improved secure routing objectives.Improved the security by doing authentication and confidentiality protection on the basis of plausible routing also named routing reachable,and illustrated it using strand space.Analysis showed the improved objectives solved some drawbacks appeared in the plausible routing,and enhanced the security of routing protocol.The proposed secure objectives further researched satellite network routing protocol formally,offering some fundamentals for later research.

  17. ISIS Topside-Sounder Plasma-Wave Investigations as Guides to Desired Virtual Wave Observatory (VWO) Data Search Capabilities

    Science.gov (United States)

    Benson, Robert F.; Fung, Shing F.

    2008-01-01

    Many plasma-wave phenomena, observed by space-borne radio sounders, cannot be properly explained in terms of wave propagation in a cold plasma consisting of mobile electrons and infinitely massive positive ions. These phenomena include signals known as plasma resonances. The principal resonances at the harmonics of the electron cyclotron frequency, the plasma frequency, and the upper-hybrid frequency are well explained by the warm-plasma propagation of sounder-generated electrostatic waves, Other resonances have been attributed to sounder-stimulated plasma instability and non-linear effects, eigenmodes of cylindrical electromagnetic plasma oscillations, and plasma memory processes. Data from the topside sounders of the International Satellites for Ionospheric Studies (ISIS) program played a major role in these interpretations. A data transformation and preservation effort at the Goddard Space Flight Center has produced digital ISIS topside ionograms and a metadata search program that has enabled some recent discoveries pertaining to the physics of these plasma resonances. For example, data records were obtained that enabled the long-standing question (several decades) of the origin of the plasma resonance at the fundamental electron cyclotron frequency to be explained [Muldrew, Radio Sci., 2006]. These data-search capabilities, and the science enabled by them, will be presented as a guide to desired data search capabilities to be included in the Virtual Wave Observatory (VWO).

  18. Verification of the Usefulness of the Trimble Rtx Extended Satellite Technology with the Xfill Function in the Local Network Implementing Rtk Measurements

    Science.gov (United States)

    Siejka, Zbigniew

    2014-12-01

    The paper presents the method of satellite measurements, which gives users the ability of GNSS continuous precise positioning in real time, even in the case of short interruptions in receiving the correction of the local ground system of measurements support. The proposed method is a combination of two satellite positioning technologies RTN GNSS and RTX Extended. In technology RTX Extended the xFill function was used for precise positioning in real time and in the local reference system. This function provides the ability to perform measurement without the need for constant communication with the ground support satellite system. Test measurements were performed on a test basis located in Krakow, and RTN GNSS positioning was done based on the national network of reference stations of the ASGEUPOS. The solution allows for short (up to 5 minutes) interruptions in radio or internet communication. When the primary stream of RTN correction is not available, then the global corrections Trimble xFill broadcasted by satellite are used. The new technology uses in the real-time data from the global network of tracking stations and contributes significantly to improving the quality and efficiency of surveying works. At present according to the authors, technology Trimble CenterPoint RTX can guarantee repeatability of measurements not worse than 3.8 cm (Trimble Survey Division, 2012). In the paper the comparative analysis of measurement results between the two technologies was performed: RTN carried out in the classic way, which was based on the corrections of the terrestrial local network of the Polish system of active geodetic network (ASG-EUPOS) and RTK xFill technology. The results were related to the data of test network, established as error free. The research gave satisfactory results and confirmed the great potential of the use of the new technology in the geodetic work realization. By combining these two technologies of GNSS surveying the user can greatly improve the

  19. Mining Data from ISI Web of Science® Reports

    Directory of Open Access Journals (Sweden)

    Alfred Kraemer

    2008-09-01

    Full Text Available Journal citation data is valuable as a selection tool for adding new journals as well as for discontinuing subscriptions that are no longer cost-effective. This article presents and discusses an example of data extraction from a typical ISI Web of Science report. The strategy was developed following a review of the data relationships and embedded data output format. While Perl was used in the example, the method described can be implemented with most programming/scripting languages. The example demonstrates also that citation-based studies and reports can be based on large sets of extracted data rather than the typical, small samples. The value of the data is discussed using a actual decision-making scenario.

  20. A satellite based global education system: The Knowledge Network of the World

    Science.gov (United States)

    Pelton, Joseph N.

    Today the entire world is struggling to meet the educational needs of more people than ever before. Nearly every country, and especially the developing world has a current and projected shortage of qualified teachers at all educational levels. As a result, there is little likelihood that the necessary educational resources of traditional approaches can be mustered to meet the clearly identified global needs. This paper expands upon a visionary proposal by Arthur C. Clarke for the development and implementation of an electronic tutor. It is demonstrated that the realization of this idea is both technologically and economically feasible and capable of addressing the educational dilemma in an economically viable fashion. Developmental design, operational cost factors are explored together with forecasts for implementation of the electronic tutor unit and the infrastructure required to provide a truly global educational capability by the year 2000. This electronic tutor system is characterized as the key element within a new Knowledge Network of the World (KNOW).

  1. Changes in satellite-derived impervious surface area at US historical climatology network stations

    Science.gov (United States)

    Gallo, Kevin; Xian, George

    2016-10-01

    The difference between 30 m gridded impervious surface area (ISA) between 2001 and 2011 was evaluated within 100 and 1000 m radii of the locations of climate stations that comprise the US Historical Climatology Network. The amount of area associated with observed increases in ISA above specific thresholds was documented for the climate stations. Over 32% of the USHCN stations exhibited an increase in ISA of ⩾20% between 2001 and 2011 for at least 1% of the grid cells within a 100 m radius of the station. However, as the required area associated with ISA change was increased from ⩾1% to ⩾10%, the number of stations that were observed with a ⩾20% increase in ISA between 2001 and 2011 decreased to 113 (9% of stations). When the 1000 m radius associated with each station was examined, over 52% (over 600) of the stations exhibited an increase in ISA of ⩾20% within at least 1% of the grid cells within that radius. However, as the required area associated with ISA change was increased to ⩾10% the number of stations that were observed with a ⩾20% increase in ISA between 2001 and 2011 decreased to 35 (less than 3% of the stations). The gridded ISA data provides an opportunity to characterize the environment around climate stations with a consistently measured indicator of a surface feature. Periodic evaluations of changes in the ISA near the USHCN and other networks of stations are recommended to assure the local environment around the stations has not significantly changed such that observations at the stations may be impacted.

  2. Role of echinenone in fluorescence quenching in IsiA aggregates from cyanobacteria

    NARCIS (Netherlands)

    D'Haene, S.; Tsoukatos, K.; Lampoura, S.S.; Matthijs, H.C.P.; Dekker, J.P.; Allen, J.F.; Gantt, E.; Goldbeck, J.H.; Osmond, B.

    2008-01-01

    We compare the carotenoid composition and the quenching properties of IsiA aggregates obtained from a Synechocystis PCC 6803 psaFJ-null mutant and from a crtO-null mutant that is unable to synthesize echinenone. Pigment analysis indicates that isolated IsiA aggregates from the psaFJ-null mutant bind

  3. Network global navigation satellite system survey to harmonize water-surface elevation data for the Rainy River Basin

    Science.gov (United States)

    Ziegeweid, Jeffrey R.; Silliker, R. Jason; Densmore, Brenda K.; Krahulik, Justin

    2016-08-15

    Continuously recording water-level streamgages in Rainy Lake and Namakan Reservoir are used to regulate water levels according to rule curves established in 2000 by the International Joint Commission; however, water levels at streamgages were referenced to a variety of vertical datums, confounding efforts to model the flow of water through the system, regulate water levels during periods of high inflow, and evaluate the effectiveness of the rule curves. In October 2014, the U.S. Geological Survey, Natural Resources Canada, International Joint Commission, and National Park Service began a joint field study with the goal of obtaining precise elevations referenced to a uniform vertical datum for all reference marks used to set water levels at streamgages throughout Rainy Lake and Namakan Reservoir. This report was prepared by the U.S. Geological Survey in cooperation with Natural Resources Canada, International Joint Commission, and National Park Service.Three field crews deployed Global Navigation Satellite System receivers statically over 16 reference marks colocated with active and discontinued water-level streamgages throughout Rainy River, Rainy Lake, Namakan Reservoir, and select tributaries of Rainy Lake and Namakan Reservoir. A Global Navigation Satellite System receiver also was deployed statically over a National Geodetic Survey cooperative base network control station for use as a quality-control reference mark. Satellite data were collected simultaneously during a 5-day period and processed independently by the U.S. Geological Survey and Natural Resources Canada to obtain accurate positioning and elevations for the 17 surveyed reference marks. Processed satellite data were used to convert published water levels to elevations above sea level referenced to the Canadian Geodetic Vertical Datum of 2013 in order to compare water-surface elevations referenced to a uniform vertical datum throughout the study area. In this report, an “offset” refers to the

  4. Investigating the Potential of Deep Neural Networks for Large-Scale Classification of Very High Resolution Satellite Images

    Science.gov (United States)

    Postadjian, T.; Le Bris, A.; Sahbi, H.; Mallet, C.

    2017-05-01

    Semantic classification is a core remote sensing task as it provides the fundamental input for land-cover map generation. The very recent literature has shown the superior performance of deep convolutional neural networks (DCNN) for many classification tasks including the automatic analysis of Very High Spatial Resolution (VHR) geospatial images. Most of the recent initiatives have focused on very high discrimination capacity combined with accurate object boundary retrieval. Therefore, current architectures are perfectly tailored for urban areas over restricted areas but not designed for large-scale purposes. This paper presents an end-to-end automatic processing chain, based on DCNNs, that aims at performing large-scale classification of VHR satellite images (here SPOT 6/7). Since this work assesses, through various experiments, the potential of DCNNs for country-scale VHR land-cover map generation, a simple yet effective architecture is proposed, efficiently discriminating the main classes of interest (namely buildings, roads, water, crops, vegetated areas) by exploiting existing VHR land-cover maps for training.

  5. Galileo satellite antenna modeling

    Science.gov (United States)

    Steigenberger, Peter; Dach, Rolf; Prange, Lars; Montenbruck, Oliver

    2015-04-01

    The space segment of the European satellite navigation system Galileo currently consists of six satellites. Four of them belong to the first generation of In-Orbit Validation (IOV) satellites whereas the other two are Full Operational Capability (FOC) satellites. High-precision geodetic applications require detailed knowledge about the actual phase center of the satellite and receiver antenna. The deviation of this actual phase center from a well-defined reference point is described by phase center offsets (PCOs) and phase center variations (PCVs). Unfortunately, no public information is available about the Galileo satellite antenna PCOs and PCVs, neither for the IOV, nor the FOC satellites. Therefore, conventional values for the IOV satellite antenna PCOs have been adopted for the Multi-GNSS experiment (MGEX) of the International GNSS Service (IGS). The effect of the PCVs is currently neglected and no PCOs for the FOC satellites are available yet. To overcome this deficiency in GNSS observation modeling, satellite antenna PCOs and PCVs are estimated for the Galileo IOV satellites based on global GNSS tracking data of the MGEX network and additional stations of the legacy IGS network. Two completely independent solutions are computed with the Bernese and Napeos software packages. The PCO and PCV values of the individual satellites are analyzed and the availability of two different solutions allows for an accuracy assessment. The FOC satellites are built by a different manufacturer and are also equipped with another type of antenna panel compared to the IOV satellites. Signal transmission of the first FOC satellite has started in December 2014 and activation of the second satellite is expected for early 2015. Based on the available observations PCO estimates and, optionally PCVs of the FOC satellites will be presented as well. Finally, the impact of the new antenna model on the precision and accuracy of the Galileo orbit determination is analyzed.

  6. A comparison of five commercial thromboplastins: ISI re-evaluation on an automated coagulometer.

    Science.gov (United States)

    Ford, K; McArdle, B; Kesteven, P J

    1995-03-01

    Five commercial rabbit brain thromboplastins were compared with an International Reference Preparation on an ACL coagulometer, using 90 patients stabilized on warfarin and 22 normal individuals. The prothrombin times were converted to INRs using the thromboplastin manufacturers' quoted ISI. The quoted ISIs were reassigned using orthogonal regression analysis and then used to recalculate INRs for patient and commercial INR control plasmas. This showed that the manufacturers' quoted ISIs and the INR control plasma results were inconsistent. With one thromboplastin the manufacturers quoted ISI changed from 1.17 to 1.05 whilst the control plasma results changed from an INR of 4.3 to an INR of 3.7 (manufacturer's INR, 3.3). In most routine laboratories ISI reassignment is not practical. We conclude that the availability of a reliable plasma calibrant is essential for the accurate calculation of INRs at a local level.

  7. Hierarchical graph-based segmentation for extracting road networks from high-resolution satellite images

    Science.gov (United States)

    Alshehhi, Rasha; Marpu, Prashanth Reddy

    2017-04-01

    Extraction of road networks in urban areas from remotely sensed imagery plays an important role in many urban applications (e.g. road navigation, geometric correction of urban remote sensing images, updating geographic information systems, etc.). It is normally difficult to accurately differentiate road from its background due to the complex geometry of the buildings and the acquisition geometry of the sensor. In this paper, we present a new method for extracting roads from high-resolution imagery based on hierarchical graph-based image segmentation. The proposed method consists of: 1. Extracting features (e.g., using Gabor and morphological filtering) to enhance the contrast between road and non-road pixels, 2. Graph-based segmentation consisting of (i) Constructing a graph representation of the image based on initial segmentation and (ii) Hierarchical merging and splitting of image segments based on color and shape features, and 3. Post-processing to remove irregularities in the extracted road segments. Experiments are conducted on three challenging datasets of high-resolution images to demonstrate the proposed method and compare with other similar approaches. The results demonstrate the validity and superior performance of the proposed method for road extraction in urban areas.

  8. Dynamic Routing Algorithm for Satellite Network Based on Ant Colony Algorithm%基于蚁群算法的卫星网动态路由算法

    Institute of Scientific and Technical Information of China (English)

    马海滨; 王汝传; 饶元

    2011-01-01

    卫星网络路由应当具有使用较小的通信开销和处理能力计算出最优路径,并能够适应卫星网络拓扑结构动态变化等特点,这与蚁群算法的特征相匹配,能很好地解决这一问题.以此为背景,提出了一种新型的基于蚁群算法的卫星网动态路由算法(DRAS-ACA),并在NS2网络仿真平台上实现了该路由算法,使用gnuplot分析了仿真结果.%Satellite network routing should have the use of smaller capacity and communication overhead to calculate the optimal path, and be able to adapt to the satellite network topology changes, and other characteristics. The Ant Colony Algorithm should be a good appraach to solve this problem. In this paper, a dynamic routing algorithm for satellite network based on ant colony algorithm (DRAS-ACA) was presented and simulated on NS2 platform,and we also analyzed the simulation results with gnuplot.

  9. PENGEMBANGAN ISI KURIKULUM PENDIDIKAN TEKNIK ALAT BERAT BERBASIS KEBUTUHAN INDUSTRI

    Directory of Open Access Journals (Sweden)

    Mochamad Bruri Triyono

    2016-12-01

    Full Text Available Penelitian ini bertujuan untuk: (1 mengetahui rumusan kompetensi tenaga mekanik alat berat sesuai standar industri; (2 mengetahui kualifikasi tenaga instruktur alat berat yang dibutuhkan industri sesuai standar industri; (3 merumuskan isi kurikulum untuk materi ajar produktif untuk menciptakan tenaga kerja di bidang alat berat. Penelitian ini merupakan penelitian survei dengan model pilihan pengembangan kurikulum Task Analysis. Penelitian dilaksanakan di industri yang bergerak di bidang alat berat dan institusi pendidikan perguruan tinggi dan SMK yang bekerja sama dengan industri alat berat yaitu PT Thiess Contractors Indonesia, PT United Tractors Indonesia, dan PT Trakindo Utama. Hasil penelitian diperoleh bahwa: (1 kompetensi mekanik alat berat meliputi: menerapkan keselamatan dan kesehatan kerja, menguasai dasar mekanik alat berat, melaksanakan perawatan dan perbaikan engine, sistem hidrolik, powertrain, sistem vehicle control, serta sistem kelistrikan alat berat minimal pada level capable (di bawah supervisi; (2 kualifikasi tenaga instruktur alat berat meliputi: memiliki kemampuan mekanik alat berat level III, memiliki kemampuan mengelola pelatihan, memiliki pengalaman kerja, serta mendapatkan pelatihan instruktur; (3 isi kurikulum untuk materi ajar produktif mekanik alat berat meliputi: dasar mekanik alat berat dan keselamatan kerja, dasar engine, dasar hidrolik, dasar vehicle control, dasar kelistrikan, materi sistem engine lanjut, sistem hidrolik lanjut, sistem powertrain lanjut, sistem vehicle control lanjut, sistem kelistrikan lanjut, product training, serta electronic machine control. Kata kunci: kompetensi, instruktur alat berat, isi kurikulum, materi ajar   THE CONTENT CURRICULLUM DEVELOPMENT OF EDUCATION TECHNIC IN HEAVY EQUIPMENT BASED ON INDUSTRIAL NEEDS ABSTRACT This study aims to: (1 find out the formula of competency for heavy equipment mechanic based on industry needs, (2 determine the qualifications of instructors in heavy

  10. LEO 卫星通信网络的移动性管理%Mobility management in LEO satellite communication networks

    Institute of Scientific and Technical Information of China (English)

    贺达健; 游鹏; 雍少为

    2016-01-01

    近年来,低轨道(Low Earth Orbit,LEO)卫星通信网络以全球覆盖、低传输时延、低功耗链路、较强的抗毁性等特点而受到广泛关注,是未来全球移动通信系统的重要组成部分。移动性管理是构建 LEO 卫星通信网络的关键技术,为推动移动性管理问题的研究,文章从 LEO 卫星通信网络的结构和特点入手,阐述了 LEO 卫星通信网络中移动性管理的分类,并分析了其相比地面移动无线网络的特殊性。从链路层、网络层、传输层三个协议层次综述了近年来 LEO 卫星通信网络移动性管理研究的国内外现状,重点介绍了移动 IPv6(Mobile IPv6,MIPv6)和无缝 IP 分集通用移动性结构(Seamless IP-diversity based Generalized Mobility Architecture,SIGMA)在 LEO 卫星通信网络中的应用。最后,指出了移动性管理的发展趋势。%In recent years,low Earth orbit (LEO)satellite communication networks attract a lot of researchers'attention for its global coverage,short propagation delay,low-power links and great invulnerabi lity performance,etc. It wi ll be an important part of the future global mobi le communication systems.Mobi lity management is a key technology for enabling service in LEO satellite communication networks.The characteristics, research status and problems of mobi lity management were analyzed.Fi rstly,a brief classification of mobi lity management of LEO satellite communications networks was provided and characteristics distinguished from terrestrial mobi lity wi reless networks were analyzed based on the architecture and features of LEO satellite communication networks. Then the state-of-the-art mobi lity management schemes in LEO satellite communication networks were summarized from link layer,network layer and transport layer.A detai led description of the application of MIPv6 and SIGMA in LEO satellite envi ronment was given. Finally,some trends of mobi lity management of LEO satellite communications networks

  11. ISIS,为何盯上中亚?

    Institute of Scientific and Technical Information of China (English)

    荆棘

    2015-01-01

    2014年6月以来,"伊斯兰国"(ISIS)的恐怖分子在叙利亚和伊拉克实施多重暴力活动,造成大量死伤,其凶残程度令人咋舌。近日,一则最新网上视频显示,疑遭ISIS绑架的日本人质汤川遥菜已被杀害,ISIS还提出要求释放一名实施自杀式攻击的女嫌犯。此事引发广泛关注,另据俄罗斯《独立报》报道,在中东地区兴风作浪的"伊斯兰国"ISIS最近盯上了中亚,决定拨款7000万美元在中亚开辟"第二战线"。这个被称为"当今世界上最危险的恐怖组织",为何盯上中亚?

  12. First results with prototype ISIS devices for ILC vertex detector

    Energy Technology Data Exchange (ETDEWEB)

    Damerell, C., E-mail: c.damerell@rl.ac.u [RAL, Oxon OX11 0QX (United Kingdom); Zhang, Z. [RAL, Oxon OX11 0QX (United Kingdom); Gao, R.; John John, Jaya; Li, Y.; Nomerotski, A. [Oxford U (United Kingdom); Holland, A.; Seabroke, G. [Centre for Electronic Imaging, Open U (United Kingdom); Havranek, M. [Czech Technical University in Prague (Czech Republic); Stefanov, K. [Sentec Ltd, Cambridge (United Kingdom); Kar-Roy, A. [Jazz Semiconductors, California (United States); Bell, R.; Burt, D.; Pool, P. [e2V Technologies, Chelmsford (United Kingdom)

    2010-12-11

    The vertex detectors at the International Linear Collider (ILC) (there will be two of them, one for each of two general purpose detectors) will certainly be built with silicon pixel detectors, either monolithic or perhaps vertically integrated. However, beyond this general statement, there is a wide range of options supported by active R and D programmes all over the world. Pixel-based vertex detectors build on the experience at the SLAC large detector (SLD) operating at the SLAC linear collider (SLC), where a 307 Mpixel detector permitted the highest physics performance at LEP or SLC. For ILC, machine conditions demand much faster readout than at SLC, something like 20 time slices during the 1 ms bunch train. The approach of the image sensor with in-situ storage (ISIS) is unique in offering this capability while avoiding the undesirable requirement of 'pulsed power'. First results from a prototype device that approaches the pixel size of 20 {mu}m square, needed for physics, are reported. The dimensional challenge is met by using a 0.18 {mu}m imaging CMOS process, instead of a conventional CCD process.

  13. LEO/MEO双层卫星网络设计及仿真%Design and Simulation on a LEO/MEO Double-Layered Satellite Network

    Institute of Scientific and Technical Information of China (English)

    张基伟; 梁俊; 肖楠; 田斌

    2011-01-01

    Aiming at the issue of simplex function and low reliability in monolayer satellite network and high ISL complexity in three-layered satellite network, a framework of LEO/MEO network is proposed. Based on the "worst observational point" and " street of coverage" theory, a discontinuous connection LFO/MEO constellation is designed, and the principle to establish ISL is put forward. Furthermore , experimental results show that the network has the ability of global coverage and is easy to establish ISL.%针对单层卫星网络功能单一、可靠性较低以及三重卫星网络链路冗余度过高、实现复杂的问题,提出了利用LEO/MEO卫星构建双层网络的构想.基于"最坏观察点"与"覆盖带"理论设计了"弱连接"的LEO/MEO双层卫星网络星座,给出了星际链路建立原则.仿真结果表明,所设计的卫星网络具有全天时全球覆盖能力,有利于星际链路的建立.

  14. Investigation into the use of satellite remote sensing data products as part of a multi-modal marine environmental monitoring network

    Science.gov (United States)

    O'Connor, Edel; Smeaton, Alan F.; O'Connor, Noel E.; Regan, Fiona

    2012-09-01

    In this paper it is investigated how conventional in-situ sensor networks can be complemented by the satellite data streams available through numerous platforms orbiting the earth and the combined analyses products available through services such as MyOcean. Despite the numerous benefits associated with the use of satellite remote sensing data products, there are a number of limitations with their use in coastal zones. Here the ability of these data sources to provide contextual awareness, redundancy and increased efficiency to an in-situ sensor network is investigated. The potential use of a variety of chlorophyll and SST data products as additional data sources in the SmartBay monitoring network in Galway Bay, Ireland is analysed. The ultimate goal is to investigate the ability of these products to create a smarter marine monitoring network with increased efficiency. Overall it was found that while care needs to be taken in choosing these products, there was extremely promising performance from a number of these products that would be suitable in the context of a number of applications especially in relation to SST. It was more difficult to come to conclusive results for the chlorophyll analysis.

  15. Model of a neural network inertial satellite navigation system capable of estimating the earth's gravitational field gradient

    Science.gov (United States)

    Devyatisil'nyi, A. S.

    2016-09-01

    A model for recognizing inertial and satellite data on an object's motion that are delivered by a set of distributed onboard sensors (newtonmeters, gyros, satellite receivers) has been described. Specifically, the model is capable of estimating the parameters of the gravitational field.

  16. Demonstration system design of double-layered optical satellite network%双层卫星光网络仿真演示系统设计

    Institute of Scientific and Technical Information of China (English)

    李勇军; 赵尚弘; 吴继礼; 朱子行; 王翔; 赵顾灏; 姜晓峰

    2011-01-01

    In order to simulate and demonstrate the maintaining and handover of inter-orbit links of double-layered optical satellite network accurately, a hardware-in-the-loop demonstration system of asynchronous handover optical satellite network was designed in the scale of 1:30. The system was composed of demonstration hardware platform and computer simulation platform which were connected by System-In-the-Loop (SITL) module. Hardware platform was made up of a circular rotor mounted two servo-optical communication terminals and four servo-optical communication terminals which were located on the two sides of the circular rotor. The former demonstrated the LEO satellites and the latter demonstrated the MEO satellites. The system period was 280 s, the rotational velocity of circular rotor was 1.28(°)/s and the handover time from LEO satellites to MEO satellites was 4 s. The software environment was composed of computer virtual networks, in which flexible on board routing and processing may be performed. The demonstration system can achieve automatic tracking, bi-directional handover and automatic pointing. It can model OIOL (optical inter-orbit links) maintaining, data relaying and bi-directional handovers between LEO satellites andMEO satellites. Experiences from the demonstration system would be useful for the realization of LEO/MEO double-layered optical satellite network in engineering.%为了精确模拟、演示验证双层卫星光网络星际激光链路的稳定和切换,按l:30的比例设计了分时切换低/中轨道(LEO/MEO:Low Earth Orbit/Medium Earth Orbit)双层卫星光网络实验演示系统.系统由SITL(System-In-the-Loop)模块将硬件平台和计算机仿真平台互联而组成.硬件平台由中心的圆形往复转台上面的2个伺服终端和两侧的4个伺服终端组成,分别模拟LEO卫星和MEO卫星.转台平台角速度为1.28(°)/s,周期为280s,切换时间为4s.软件部分由虚拟网络组成,具有灵活的星上路由和处理

  17. SPARTAN: a global network to evaluate and enhance satellite-based estimates of ground-level particulate matter for global health applications

    Directory of Open Access Journals (Sweden)

    G. Snider

    2014-07-01

    Full Text Available Ground-based observations have insufficient spatial coverage to assess long-term human exposure to fine particulate matter (PM2.5 at the global scale. Satellite remote sensing offers a promising approach to provide information on both short- and long-term exposure to PM2.5 at local-to-global scales, but there are limitations and outstanding questions about the accuracy and precision with which ground-level aerosol mass concentrations can be inferred from satellite remote sensing alone. A key source of uncertainty is the global distribution of the relationship between annual average PM2.5 and discontinuous satellite observations of columnar aerosol optical depth (AOD. We have initiated a global network of ground-level monitoring stations designed to evaluate and enhance satellite remote sensing estimates for application in health effects research and risk assessment. This Surface PARTiculate mAtter Network (SPARTAN includes a global federation of ground-level monitors of hourly PM2.5 situated primarily in highly populated regions and collocated with existing ground-based sun photometers that measure AOD. The instruments, a three-wavelength nephelometer and impaction filter sampler for both PM2.5 and PM10, are highly autonomous. Hourly PM2.5 concentrations are inferred from the combination of weighed filters and nephelometer data. Data from existing networks were used to develop and evaluate network sampling characteristics. SPARTAN filters are analyzed for mass, black carbon, water-soluble ions, and metals. These measurements provide, in a variety of global regions, the key data required to evaluate and enhance satellite-based PM2.5 estimates used for assessing the health effects of aerosols. Mean PM2.5 concentrations across sites vary by an order of magnitude. Initial measurements indicate that the AOD column to PM2.5 ratio is driven temporally primarily by the vertical profile of aerosol scattering; and spatially by a~ more complex interaction

  18. Analysis of routing strategies in next -generation LEO satellite networks%下一代LEO卫星网络路由策略分析

    Institute of Scientific and Technical Information of China (English)

    罗雪山; 李健杰; 易先清; 唐曙

    2011-01-01

    鉴于LEO卫星网络有限的资源和高昂的建设维护成本,研究有效的LEO卫星网络路由策略成为下一代LEO卫星网络建设的关键问题.LEO卫星网络具有不同于传统的地面网络的特性,首先从对路由影响的角度对这些特性进行归纳,随后依据这些特性总结出侧重于网络拓扑结构、路由更新和负载平衡3个方面的解决方案,分析了每种方案特点,为进一步设计满足应用需求的、更为有效的下一代卫星网络路由策略奠定基础.%Studying effective routing strategies has become a critical issue in construction of LEO satellite networks because satellite network resources are very limited and maintenance costs are very great.Firstly, features of LEO satellite networks distinct from terrestrial networks are summed up according to their effects on routing issues.Subsequently, a survey of various routing strategies paying particular attention to these problems from aspects of topology, routing refreshment and load balancing is provided.By analyzing the characteristic of routing schemes in their various aspects, a foundation of designing more effective routing strategies to meet the needs of future applications is laid.

  19. Energy-Efficient Source Authentication for Secure Group Communication with Low-Powered Smart Devices in Hybrid Wireless/Satellite Networks

    Directory of Open Access Journals (Sweden)

    Baras JohnS

    2011-01-01

    Full Text Available We describe a new class of lightweight, symmetric-key digital certificates called extended TESLA certificates and a source authentication protocol for wireless group communication that is based on the certificate. The certificate binds the identity of a wireless smart device to the anchor element of its key chain; keys from the chain are used for computing message authentication codes (MACs on messages sourced by the device. The authentication protocol requires a centralized infrastructure in the network: we describe the protocol in a hybrid wireless network with a satellite overlay interconnecting the wireless devices. The satellite is used as the Certificate Authority (CA and also acts as the proxy for the senders in disclosing the MAC keys to the receivers. We also design a probabilistic nonrepudiation mechanism that utilizes the satellite's role as the CA and sender proxy. Through analysis, we show that the authentication protocol is secure against malicious adversaries. We also present detailed simulation results that demonstrate that the proposed protocol is much cheaper than traditional public key-based authentication technologies for metrics like processing delay, storage requirements, and energy consumption of the smart devices.

  20. Comparison of the toxicity profiles of ISIS 1082 and ISIS 2105, phosphorothioate oligonucleotides, following subacute intradermal administration in Sprague-Dawley rats.

    Science.gov (United States)

    Henry, S P; Grillone, L R; Orr, J L; Bruner, R H; Kornbrust, D J

    1997-01-15

    The systemic toxicity of two phosphorothioate oligonucleotides specific for herpes simplex viruses (ISIS 1082) and human papiloma virus (ISIS 2105) were evaluated following repeated intradermal injections of vehicle control, 0.33, 2.17, or 21.7 mg/kg daily to Sprague-Dawley rats (10/sex/group) for 14 days. Animals were sacrificed 1 day after the last dose, except for a portion of the ISIS 1082-treated animals (5/sex/group) which were maintained for an additional 14-day recovery period. The profile of alterations noted for both compounds was very similar. Other than local signs of irritation at the site of injection, there were no clinical signs of toxicity or treatment-related mortality, but there was a slight decrease in body weight gain for the 21.7 mg/kg dose groups. Alterations in hematology parameters included dose-dependent thrombocytopenia and anemia. Alterations in serum chemistry parameters were suggestive of mild alterations in hepatic metabolism, with increases in liver transaminases and bilirubin, along with decreases in albumin and cholesterol. Both spleen and liver weights were significantly elevated in a dose-dependent fashion. Histopathological alterations noted in liver, kidney, lung, injection site skin, and spleen were characterized as perivascular and interstitial infiltrates of macrophages and monocytes. Additional microscopic alterations in the spleen included mild lymphoid hyperplasia (seen in lymph nodes as well), and extramedullary hematopoiesis. Treatment-related cytopenias were likely related to mild, focal hypocellularity in the bone marrow. Alterations in ISIS 1082-treated animals were only partially reversed following the 14-day treatment-free period. In conclusion, repeated intradermal administration of ISIS 1082 and ISIS 2105 produced a similar spectrum of toxicities, with liver, kidney, spleen, and bone marrow being identified as target tissues.

  1. Intellectualisation of isiXhosa litera- ture: the case of Jeff Opland

    African Journals Online (AJOL)

    The origins of the intellectualisation of written isiXhosa literature are often ... awarded the English Academy of Southern Africa's Sol Plaatje Prize for Translation .... This thesis was completed and awarded by Rhodes University in April 2017.

  2. Literaure search for intermittent rivers research using ISI Web of Science

    Data.gov (United States)

    U.S. Environmental Protection Agency — The dataset is the bibliometric information included in the ISI Web of Science database of scientific literature. Table S2 accessible from the dataset link provides...

  3. Optimising a muon spectrometer for measurements at the ISIS pulsed muon source

    Energy Technology Data Exchange (ETDEWEB)

    Giblin, S.R. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX (United Kingdom); School of Physics and Astronomy, Cardiff University, Cardiff CF24 3AA (United Kingdom); Cottrell, S.P., E-mail: stephen.cottrell@stfc.ac.uk [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX (United Kingdom); King, P.J.C.; Tomlinson, S.; Jago, S.J.S.; Randall, L.J.; Roberts, M.J.; Norris, J.; Howarth, S.; Mutamba, Q.B.; Rhodes, N.J.; Akeroyd, F.A. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX (United Kingdom)

    2014-07-01

    This work describes the development of a state-of-the-art muon spectrometer for the ISIS pulsed muon source. Conceived as a major upgrade of the highly successful EMU instrument, emphasis has been placed on making effective use of the enhanced flux now available at the ISIS source. This has been achieved both through the development of a highly segmented detector array and enhanced data acquisition electronics. The pulsed nature of the ISIS beam is particularly suited to the development of novel experiments involving external stimuli, and therefore the ability to sequence external equipment has been added to the acquisition system. Finally, the opportunity has also been taken to improve both the magnetic field and temperature range provided by the spectrometer, to better equip the instrument for running the future ISIS user programme.

  4. Looking to 2050: The USGS Integrated Software for Imagers and Spectrometers (ISIS)

    Science.gov (United States)

    Becker, T. L.; Edmundson, K. L.; Sides, S.; Hare, T. M.; Laura, J. R.

    2017-02-01

    Astrogeology Science Center develops and maintains software (ISIS) in support of planetary data for a diverse set of missions. We plan to provide support through the future while adapting to changes in hardware, software, and science requirements.

  5. ISI Web of Knowledge 在科技文章写作中的应用

    Institute of Scientific and Technical Information of China (English)

    彭蕾蕾; 吴建社

    2009-01-01

    ISI Web of Knowledge是一个基于Web而构建的整合的数字研究环境,直接面向科研需要的学术资源,内容涉及诸多学科.主要介绍ISI Web of Knowledge的检索功能、Journal Citation Reports、MyEndNote Web工具在撰写科技文章时的应用.

  6. ISI Proceedings的主要功能及其使用技巧

    Institute of Scientific and Technical Information of China (English)

    赵琪

    2008-01-01

    ISI Proceedings是世界上最有影响的会议录文献检索数据库的web版。本文简要介绍了ISI Proceedings的主要特点及检索方法和技巧。希望通过本篇的介绍,能帮助会议录文献的查阅者获得最实际的帮助。

  7. Pemanfaatan Isi Rumen Dari Limbah Rumah Potong Hewan Sebagai Bahan Pakan Dalam Ransum Ikan Nila

    OpenAIRE

    Noor Arida Fauzana

    2008-01-01

    Penelitian ini bertujuan untuk (1) mengetahui kandungan gizi isi rumen sebagai bahan pakan ikan yang bergizi , 2) mengetahui pengaruh kandungan protein dalam ransum ikan dan penambahan filtrat air abu sekam terhadap pertumbuhan ikan dan (3) menetapkan konsentrasi isi rumen yang terbaik sebagai bahan pakan dalam ransum ikan. Parameter yang diamati adalah pertumbuhan mutlak ikan nila yang meliputi pertambahan berat (gr) dan pertambahan panjang (cm), pertumbuhan relatif (%) baik berat maupun ...

  8. Uji Kualitas Air Minum Isi Ulang di Kecamatan Sukodono, Sidoarjo Ditinjau Dari Perilaku dan Pemeliharaan Alat

    Directory of Open Access Journals (Sweden)

    Yoga Ardy Pradana

    2013-09-01

    Full Text Available Seiring dengan kemajuan teknologi sekarang ini dan diiringi dengan semakin sibuknya aktivitas manusia maka masyarakat cenderung memilih cara yang lebih praktis dengan biaya relatif murah dalam memenuhi kebutuhan air minum yaitu dengan menggunakan air minum isi ulang  terutama di kecamatan Sukodono, Sidoarjo. Agar air minum isi ulang yang dikonsumsi oleh masyarakat di kecamatan Sukodono, Sidoarjo aman untuk dikonsumsi, maka perlu dilakukan uji kualitas apakah kandungan dalam air minum isi ulang sudah memenuhi Peraturan Menteri Kesehatan No 492/MENKES/PER/IV/2010 tantang persyaratan kualitas air minum. Parameter yang diuji meliputi Total Coliform, TDS, Kekeruhan dan Warna. Kualitas air minum isi ulang ditunjang oleh cara pemeliharaan peralatan produksi. Prosedur pemeliharaan alat dari masing-masing depo air minum isi ulang diperoleh melalui wawancara dan penggunaan kuesioner. Hasil uji laboratorium dari 8 depo air minum isi ulang ada yang belum memenuhi parameter Total Koliform sebanyak 5 depo. Berdasarkan hasil kuesioner 5 depo tersebut termasuk dalam kategori cukup, yang berarti masih kurang dalam melakukan pemeliharaan alat.

  9. A New Traffic Flow Prediction Algorithm for Satellite Communication Network%一种新的卫星通信网流量预测算法*

    Institute of Scientific and Technical Information of China (English)

    秦红祥; 杨飞

    2013-01-01

      在通信网络的设计中,使用基于流量预测的网络规划已成为LTE发展的必然趋势。与地面网络不同,卫星网络由于受资源受限和拓扑时变的不利影响,其流量预测算法必须能兼顾精度和效率,这令传统的地面网络预测方法已不再适用。为了解决以上问题,提出了一种新的基于小波回声状态网络的流量预测算法,该算法通过小波多尺度分解的信号处理方法屏蔽了网络流量的噪声,而后结合了无反馈的回声状态网络联合进行预测。仿真证明,新算法相比传统算法能大幅提升网络流量的预测精度和运行效率,为卫星网络的流量规划提供了强有力的决策支持。%In the design of a communication network,it has become an inevitable trend with LET development to use traffic flow prediction method for network planning. Due to suffer from the constrained resource and change-able topology,the traffic flow prediction algorithm of the satellite networks which is different from terrestrial net-works,should fully take into account the accuracy and efficiency,so the traditional prediction methods for ter-restrial networks are no longer fit for application. In order to resolve this problem,a new traffic flow prediction algorithm based on wavelet and echo state networks is proposed in this paper. The new algorithm uses the signal processing method based on multi-scale decomposition of wavelet to shield the noise of the network traffic,and it combines with the non-feedback echo state network to predict. The simulation results show that the new algorithm can greatly improve the prediction accuracy and running efficiency of network traffic compared with traditional al-gorithms,so it provides a more scientific decision support for satellite communication network traffic planning.

  10. Tracing the historical and ideological roots of ISIS: Shi’ite or Sunni?

    Directory of Open Access Journals (Sweden)

    Makrum Makrum

    2016-12-01

    Full Text Available This article describes a comprehensive study of ISIS (the Islamic States of Iraq and Syiria by examining both their historical and ideological roots, Shi’ite or Sunni – including their patterns and terror motives and also by mapping their doctrinal understanding that they adopt. The data stem from various studies, books and news that are widely spread in mass media by literature study (library research. This study was inspired by the emergence of ISIS which in recent years has shocked the world for their savagery and ferocity in committing the murder. Moreover, their leader (Abu Bakr al-Baghdadi has declared himself as the caliph and called on Muslims worldwide to join them. That issue has been a controversy across the Muslim world; many Muslim groups accepted and joined the ISIS, while others rejected its presence. Based on these library research results, it can be inferred that, historically ISIS has existed since 2004 and the origin of ISIS cannot be separated from the existence of Tawhid wa alJihad. In terms of doctrine, the concept of shared leadership of ISIS tends to lead to Sunnis, although al-Baghdadi himself does not meet the criteria to be appointed as caliph. Personally, al-Baghdadi does not posses the leadership capacity required as a caliph, based on one of the caliph’s criteria, that is ‘adalah (justice that he does not have. Artikel ini, dengan menggunakan pendekatan kualitatif, mengkaji akar sejarah dan ideologi ISIS, Syi’ah atau Sunni –termasuk di dalamnya pola dan motif teror–, kemudian memetakan paham doktrinal yang mereka anut agar diperoleh kajian yang komprehensif tentang ISIS. Data diperoleh dari studi kepustakaan (library research yang berasal dari berbagai hasil penelitian, buku, dan berita-berita di media massa. Penulisannya terinspirasi oleh kemunculan ISIS yang pada beberapa tahun terakhir telah menghebohkan masyarakat dunia, karena kebiadaban dan keganasannya dalam melakukan pembunuhan. Selain dari itu

  11. Wave activity (planetary, tidal) throughout the middle atmosphere (20-100km) over the CUJO network: Satellite (TOMS) and Medium Frequency (MF) radar observations

    OpenAIRE

    Manson, A. H.; Meek, C. E.; Chshyolkova, T.; Avery, S. K.; Thorsen, D.; MacDougall, J.W.; Hocking, W.; Murayama, Y.; Igarashi, K

    2005-01-01

    Planetary and tidal wave activity in the tropopause-lower stratosphere and mesosphere-lower thermosphere (MLT) is studied using combinations of ground-based (GB) and satellite instruments (2000-2002). The relatively new MFR (medium frequency radar) at Platteville (40° N, 105° W) has provided the opportunity to create an operational network of middle-latitude MFRs, stretching from 81° W-142° E, which provides winds and tides 70-100km. CUJO (Canada U.S. Japan Opp...

  12. Analytical Study of Interdisciplinary Relations in Selected High Priority Areas of Science and Technology Based on Data of ISI Database

    Directory of Open Access Journals (Sweden)

    Mehri Sedighi

    2014-03-01

    Full Text Available The purpose of this research is to investigate the interdisciplinary relations in selected high priority areas of science and technology based on ISI data. This is an applied study using scientometric, citation analysis and network analysis methods. After identifying and extracting data from WOS, in order to determine the interdisciplinary relations and the evolution of these relationships, all citations of these records have been analysed. In order to judge the interdisciplinarity of data, the results of the two approaches have been considered: 1-To determine the subject areas of the journals 2- To determine the institutional affiliation of the authors.There is a positive correlation between co-authorship and interdisciplinary approach in all studied areas. There is no significant relation between the number of citations and interdisciplinary approach. Mapping of interdisciplinary relationships in nanotechnology showed this is a unique method to discover the structural patterns of a research area.

  13. Integrated Science Investigation of the Sun (ISIS): Design of the Energetic Particle Investigation

    Science.gov (United States)

    McComas, D. J.; Alexander, N.; Angold, N.; Bale, S.; Beebe, C.; Birdwell, B.; Boyle, M.; Burgum, J. M.; Burnham, J. A.; Christian, E. R.; Cook, W. R.; Cooper, S. A.; Cummings, A. C.; Davis, A. J.; Desai, M. I.; Dickinson, J.; Dirks, G.; Do, D. H.; Fox, N.; Giacalone, J.; Gold, R. E.; Gurnee, R. S.; Hayes, J. R.; Hill, M. E.; Kasper, J. C.; Kecman, B.; Klemic, J.; Krimigis, S. M.; Labrador, A. W.; Layman, R. S.; Leske, R. A.; Livi, S.; Matthaeus, W. H.; McNutt, R. L.; Mewaldt, R. A.; Mitchell, D. G.; Nelson, K. S.; Parker, C.; Rankin, J. S.; Roelof, E. C.; Schwadron, N. A.; Seifert, H.; Shuman, S.; Stokes, M. R.; Stone, E. C.; Vandegriff, J. D.; Velli, M.; von Rosenvinge, T. T.; Weidner, S. E.; Wiedenbeck, M. E.; Wilson, P.

    2016-12-01

    The Integrated Science Investigation of the Sun (ISIS) is a complete science investigation on the Solar Probe Plus (SPP) mission, which flies to within nine solar radii of the Sun's surface. ISIS comprises a two-instrument suite to measure energetic particles over a very broad energy range, as well as coordinated management, science operations, data processing, and scientific analysis. Together, ISIS observations allow us to explore the mechanisms of energetic particles dynamics, including their: (1) Origins—defining the seed populations and physical conditions necessary for energetic particle acceleration; (2) Acceleration—determining the roles of shocks, reconnection, waves, and turbulence in accelerating energetic particles; and (3) Transport—revealing how energetic particles propagate from the corona out into the heliosphere. The two ISIS Energetic Particle Instruments measure lower (EPI-Lo) and higher (EPI-Hi) energy particles. EPI-Lo measures ions and ion composition from ˜20 keV/nucleon-15 MeV total energy and electrons from ˜25-1000 keV. EPI-Hi measures ions from ˜1-200 MeV/nucleon and electrons from ˜0.5-6 MeV. EPI-Lo comprises 80 tiny apertures with fields-of-view (FOVs) that sample over nearly a complete hemisphere, while EPI-Hi combines three telescopes that together provide five large-FOV apertures. ISIS observes continuously inside of 0.25 AU with a high data collection rate and burst data (EPI-Lo) coordinated with the rest of the SPP payload; outside of 0.25 AU, ISIS runs in low-rate science mode whenever feasible to capture as complete a record as possible of the solar energetic particle environment and provide calibration and continuity for measurements closer in to the Sun. The ISIS Science Operations Center plans and executes commanding, receives and analyzes all ISIS data, and coordinates science observations and analyses with the rest of the SPP science investigations. Together, ISIS' unique observations on SPP will enable the

  14. Integrated Satellite-HAP Systems

    DEFF Research Database (Denmark)

    Cianca, Ernestina; De Sanctis, Mauro; De Luise, Aldo

    2005-01-01

    for an efficient hybrid terrestrial-satellite communication system. Two integrated HAP-satellite scenarios are presented, in which the HAP is used to overcome some of the shortcomings of satellite- based communications. Moreover, it is shown that the integration of HAPs with satellite systems can be used......Thus far, high-altitude platform (HAP)-based systems have been mainly conceived as an alternative to satellites for complementing the terrestrial network. This article aims to show that HAP should no longer be seen as a competitor technology by investors of satellites, but as a key element...

  15. Improved monitoring of phytoplankton bloom dynamics in a Norwegian fjord by integrating satellite data, pigment analysis, and Ferrybox data with a coastal observation network

    Science.gov (United States)

    Volent, Zsolt; Johnsen, Geir; Hovland, Erlend K.; Folkestad, Are; Olsen, Lasse M.; Tangen, Karl; Sørensen, Kai

    2011-01-01

    Monitoring of the coastal environment is vitally important as these areas are of economic value and at the same time highly exposed to anthropogenic influence, in addition to variation of environmental variables. In this paper we show how the combination of bio-optical data from satellites, analysis of water samples, and a ship-mounted automatic flow-through sensor system (Ferrybox) can be used to detect and monitor phytoplankton blooms both spatially and temporally. Chlorophyll a (Chl a) data and turbidity from Ferrybox are combined with remotely sensed Chl a and total suspended matter from the MERIS instrument aboard the satellite ENVISAT (ENVIronmental SATellite) European Space Agency. Data from phytoplankton speciation and enumeration obtained by a national coastal observation network consisting of fish farms and the Norwegian Food Safety Authority are supplemented with data on phytoplankton pigments. All the data sets are then integrated in order to describe phytoplankton bloom dynamics in a Norwegian fjord over a growth season, with particular focus on Emiliania huxleyi. The approach represents a case example of how coastal environmental monitoring can be improved with existing instrument platforms. The objectives of the paper is to present the operative phytoplankton monitoring scheme in Norway, and to present an improved model of how such a scheme can be designed for a large part of the world's coastal areas.

  16. A wavelet-based non-linear autoregressive with exogenous inputs (WNARX) dynamic neural network model for real-time flood forecasting using satellite-based rainfall products

    Science.gov (United States)

    Nanda, Trushnamayee; Sahoo, Bhabagrahi; Beria, Harsh; Chatterjee, Chandranath

    2016-08-01

    Although flood forecasting and warning system is a very important non-structural measure in flood-prone river basins, poor raingauge network as well as unavailability of rainfall data in real-time could hinder its accuracy at different lead times. Conversely, since the real-time satellite-based rainfall products are now becoming available for the data-scarce regions, their integration with the data-driven models could be effectively used for real-time flood forecasting. To address these issues in operational streamflow forecasting, a new data-driven model, namely, the wavelet-based non-linear autoregressive with exogenous inputs (WNARX) is proposed and evaluated in comparison with four other data-driven models, viz., the linear autoregressive moving average with exogenous inputs (ARMAX), static artificial neural network (ANN), wavelet-based ANN (WANN), and dynamic nonlinear autoregressive with exogenous inputs (NARX) models. First, the quality of input rainfall products of Tropical Rainfall Measuring Mission Multi-satellite Precipitation Analysis (TMPA), viz., TRMM and TRMM-real-time (RT) rainfall products is assessed through statistical evaluation. The results reveal that the satellite rainfall products moderately correlate with the observed rainfall, with the gauge-adjusted TRMM product outperforming the real-time TRMM-RT product. The TRMM rainfall product better captures the ground observations up to 95 percentile range (30.11 mm/day), although the hit rate decreases for high rainfall intensity. The effect of antecedent rainfall (AR) and climate forecast system reanalysis (CFSR) temperature product on the catchment response is tested in all the developed models. The results reveal that, during real-time flow simulation, the satellite-based rainfall products generally perform worse than the gauge-based rainfall. Moreover, as compared to the existing models, the flow forecasting by the WNARX model is way better than the other four models studied herein with the

  17. Satellite Communication.

    Science.gov (United States)

    Technology Teacher, 1985

    1985-01-01

    Presents a discussion of communication satellites: explains the principles of satellite communication, describes examples of how governments and industries are currently applying communication satellites, analyzes issues confronting satellite communication, links mathematics and science to the study of satellite communication, and applies…

  18. ESA's satellite communications programme

    Science.gov (United States)

    Bartholome, P.

    1985-02-01

    The developmental history, current status, and future plans of the ESA satellite-communications programs are discussed in a general survey and illustrated with network diagrams and maps. Consideration is given to the parallel development of national and European direct-broadcast systems and telecommunications networks, the position of the European space and electronics industries in the growing world market, the impact of technological improvements (both in satellite systems and in ground-based networks), and the technological and commercial advantages of integrated space-terrestrial networks. The needs for a European definition of the precise national and international roles of satellite communications, for maximum speed in implementing such decisions (before the technology becomes obsolete), and for increased cooperation and standardization to assure European equipment manufacturers a reasonable share of the market are stressed.

  19. ISIS Cartographic Tools for the Dawn Framing Camera and Visual and Infrared Spectrometer

    Science.gov (United States)

    Anderson, J.; Becker, K. J.; Titus, T. N.; De sanctis, M.; Nathues, A.; Tosi, F.; Schroeder, S.; Le Corre, L.; Kelley, M. S.; Raymond, C. A.; Russell, C. T.

    2011-12-01

    Launched in September 2007, the Dawn spacecraft houses two imaging instruments: the framing camera (FC) and the Visual and Infrared Spectrometer (VIR) [1]. The spacecraft began orbiting asteroid 4 Vesta in July 2011 and over the course of one year will systematically map the body with both instruments. Camera model software and Dawn FC and VIR readers have been developed in the USGS Integrated Software for Imager and Spectrometers (ISIS) [2]. The readers, "dawnfc2isis" and "dawnvir2isis", convert both Planetary Data System (PDS) raw Experiment Data Records (EDRs) and calibrated Reduced Data Records (RDRs) into the native ISIS3 cube format. The ISIS camera models allow for orthorectification of the Vesta FC and VIR cubes to a variety of cartographic map projections using the long-standing "cam2map" application. Other standard tools such as "qview" for visualization and photometric processing applications (e.g.,"photomet" and "phocube") are available for use because of the integration of the new readers and camera models into ISIS [3]. These tools for Dawn cartographic and scientific analysis of Dawn data will be available for download in the October 2011 release of ISIS. The software release is timely as the Dawn image EDR data will be publicly released to the science community by the PDS within 90 days after each acquisition phase. Therefore, raw Vesta approach images will be available in November 2011. Raw images for other acquisition phases including survey, high altitude (HAMO) and low altitude (LAMO) mapping orbits will be delivered throughout 2012 [4]. Currently, there are no plans to include radiometric processing software for FC or VIR into ISIS. However, radiometrically calibrated PDS images (RDRs) will be publicly released six months after Vesta departure. [1] Russell, C.T., et al. (2007) Exploring the asteroid belt with ion propulsion: Dawn mission history, status and plans, Advances in Space Research, Volume 40, Issue 2, pages 193-201. [2] Anderson, J

  20. Feasibility Analysis on the Utilization of the Iridium Satellite Communications Network for Resident Space Objects in Low Earth Orbit

    Science.gov (United States)

    2013-03-21

    equatorial speed. Ideally, the GEO satellite remains directly overhead in the absence of perturbing forces. Of course , perturbing forces exist and cause a...respectively. Assuming a mean Earth radius of 6371 km, the Earth- central angles and can be found from trigonometry using the footprint

  1. Firing statistics of inhibitory neuron with delayed feedback. I. Output ISI probability density.

    Science.gov (United States)

    Vidybida, A K; Kravchuk, K G

    2013-06-01

    Activity of inhibitory neuron with delayed feedback is considered in the framework of point stochastic processes. The neuron receives excitatory input impulses from a Poisson stream, and inhibitory impulses from the feedback line with a delay. We investigate here, how does the presence of inhibitory feedback affect the output firing statistics. Using binding neuron (BN) as a model, we derive analytically the exact expressions for the output interspike intervals (ISI) probability density, mean output ISI and coefficient of variation as functions of model's parameters for the case of threshold 2. Using the leaky integrate-and-fire (LIF) model, as well as the BN model with higher thresholds, these statistical quantities are found numerically. In contrast to the previously studied situation of no feedback, the ISI probability densities found here both for BN and LIF neuron become bimodal and have discontinuity of jump type. Nevertheless, the presence of inhibitory delayed feedback was not found to affect substantially the output ISI coefficient of variation. The ISI coefficient of variation found ranges between 0.5 and 1. It is concluded that introduction of delayed inhibitory feedback can radically change neuronal output firing statistics. This statistics is as well distinct from what was found previously (Vidybida and Kravchuk, 2009) by a similar method for excitatory neuron with delayed feedback.

  2. Uncertainties in NDE Reliability and Assessing the Impact on RI-ISI

    Energy Technology Data Exchange (ETDEWEB)

    Doctor, Steven R.; Anderson, Michael T.

    2010-08-01

    A major thrust in the past 20 years has been to upgrade nondestructive examinations (NDE) for use in inservice inspection (ISI) programs to more effectively manage degradation at operating nuclear power plants. Risk-informed ISI (RI-ISI) is one of the outcomes of this work, and this approach relies heavily on the reliability of NDE, when properly applied, to detect sources of expected degradation. There have been a number of improvements in the reliability of NDE, specifically in ultrasonic testing (UT), through training of examiners, and improved equipment and procedure development. However, the most significant improvements in UT were derived by moving from prescriptive requirements to performance based requirements. Even with these substantial improvements, NDE contains significant uncertainties and RI-ISI programs need to address and accommodate this factor. As part of the work that PNNL is conducting for the U. S. Nuclear Regulatory Commission, Office of Nuclear Regulatory Research, we are examining the impact of these uncertainties on the effectiveness of RI-ISI programs.

  3. Satellite orbit determination and gravity field recovery from satellite-to-satellite tracking

    Science.gov (United States)

    Wakker, K. F.; Ambrosius, B. A. C.; Leenman, H.

    1989-07-01

    Studies on satellite-to-satellite tracking (SST) with POPSAT (a geodetic satellite concept) and a ERS-class (Earth observation) satellite, a Satellite-to-Satellite Tracking (SST) gravity mission, and precise gravity field determination methods and mission requirements are reported. The first two studies primarily address the application of SST between the high altitude POPSAT and an ERS-class or GRM (Geopotential Research Mission) satellite to the orbit determination of the latter two satellites. Activities focussed on the determination of the tracking coverage of the lower altitude satellite by ground based tracking systems and by POPSAT, orbit determination error analysis and the determination of the surface forces acting on GRM. The third study surveys principles of SST, uncertainties of existing drag models, effects of direct luni-solar attraction and tides on orbit and the gravity gradient observable. Detailed ARISTOTELES (which replaced POPSAT) orbit determination error analyses were performed for various ground based tracking networks.

  4. 基于无速率码实现全球信息分发的双层卫星网络设计%Design of Double-layered Satellite Network to Worldwide Information Distribution Based on Rateless Codes

    Institute of Scientific and Technical Information of China (English)

    王闯; 张洪; 张威; 张更新

    2015-01-01

    This paper proposes a double-layered satellite information distribution network consisting of the GEO satel-lites and LEO satellites, which is based on the disruption tolerant characteristics of rateless codes in information distribu-tion. In the architecture of this satellite network, GEO constellation is used as the outer backbone network to provide a wide range of coverage in low latitudes, as well as to ensure the users capacity, while LEO constellation is used as the inner en-hanced network to make up the shortage of GEO backbone network's coverage. In the design of the satellite constellation net-works, considering the coverage characteristics of GEO satellites and LEO satellites, fewer satellites are adopted to achieve a worldwide information disruption tolerant distribution capacity, combined with the disruption tolerant characteristics of rateless codes. This paper simulates and analyzes the coverage capacity and the average elevation angle of the designed net-work, and the result verifies that the network can achieve a worldwide information distribution.%文章基于无速率编码在信息分发中容中断的特性,提出一种采用GEO卫星和LEO卫星组成的双层卫星信息分发网络。在该卫星网络的体系架构中,采用GEO星座作为外层骨干网络,提供中低纬度的大范围覆盖,保证用户的容量,而采用LEO星座作为内层的增强网络,弥补GEO骨干网络的覆盖不足。在卫星网络的星座设计中,考虑GEO卫星、LEO卫星的覆盖特点,结合无速率编码的容中断特性,采用较少的卫星实现信息在全球范围内的容中断分发。文章对所设计的双层卫星网络覆盖性能和平均通信仰角进行了仿真分析,验证了该网络能够实现全球范围的信息分发。

  5. ISI Web of Science数据库检索系统浅析

    Institute of Scientific and Technical Information of China (English)

    阮伟娟

    2006-01-01

    本文从ISI Web of Knowledge入手引出ISI Web of Science数据库,在简述ISI Web of Science这个多学科综合性学术期刊数据库的特点及其优越性的基础上;逐一介绍此数据库的检索系统所提供的快速检索、普通检索、被引文献检索、化学结构检索、高级检索等检索方法;以及检索方法的具体应用和检索结果的处理.

  6. Las publicaciones de los investigadores mexicanos en el ISI: realidad o mito del SNI

    Directory of Open Access Journals (Sweden)

    Gerardo Reyes Ruiz

    2012-01-01

    Full Text Available En el presente artículo se muestra la relevancia de la investigación mexicana en el ámbito internacional, con base en el nivel de publicación alcanzado por los investigadores mexicanos en las revistas del Institute for Scientific Information (ISI de 1997 a 2008. Asimismo, y para el subperiodo de 1997 a 2002, se valora si existe una correspondencia entre el nivel de publicación ISI y los investigadores que formaron parte del Sistema Nacional de Investigadores (SNI, con el fin de conocer si el serparte de dicho programa está relacionado con un nivel de publicación de más calidad (como realmente es el publicar en revistas indexadas en el ISI.

  7. ISY Mission to Planet Earth Conference: A planning meeting for the International Space Year

    Science.gov (United States)

    Meyerson, Harvey

    1991-01-01

    A major theme was the opportunity offered by the International Space Year (ISY) to initiate a long-term program of Earth observation mission coordination and worldwide data standardization. The challenge is immense and extremely time critical. A recommendation was made to inventory the capabilities of Earth observing spacecraft scheduled during the next decade. The ISY effort to strengthen coordination and standardization should emphasize global issues, and also regional initiatives of particular relevance to developing nations. The concepts of a Global Information System Test (GIST) was accepted and applied to specific issues of immediate concern. The importance of ISY Earth observation initiatives extending beyond research to include immediate and direct applications for social and economic development was stressed. Several specific Mission to Planet Earth proposals were developed during the Conference. A mechanism was set up for coordinating participation of the national space agencies or equivalent bodies.

  8. Iterative nonlinear ISI cancellation in optical tilted filter-based Nyquist 4-PAM system

    Science.gov (United States)

    Ju, Cheng; Liu, Na

    2016-09-01

    The conventional double sideband (DSB) modulation and direct detection scheme suffers from severer power fading, linear and nonlinear inter-symbol interference (ISI) caused by fiber dispersion and square-law direct detection. The system's frequency response deteriorates at high frequencies owing to the limited device bandwidth. Moreover, the linear and nonlinear ISI is enhanced induced by the bandwidth limited effect. In this paper, an optical tilted filter is used to mitigate the effect of power fading, and improve the high frequency response of bandwidth limited device in Nyquist 4-ary pulse amplitude modulation (4-PAM) system. Furtherly, iterative technique is introduced to mitigate the nonlinear ISI caused by the combined effects of electrical Nyquist filter, limited device bandwidth, optical tilted filter, dispersion, and square-law photo-detection. Thus, the system's frequency response is greatly improved and the delivery distance can be extended.

  9. COG risk informed in-service inspection (RI-ISI) pilot study

    Energy Technology Data Exchange (ETDEWEB)

    Rezaie-Manesh, M. [Ontario Power Generation, Toronto, Ontario (Canada); O' Regan, P. [Electric Power Research Inst. (EPRI), Palo Alto, California (United States); Chesworth, S. [Structural Integrity Associates, Inc., San Francisco, California (United States)

    2011-07-01

    In 2009, CNSC prepared 'Guidelines for Risk-Informed In-service Inspection for Piping,' that provided guidance for licensees to develop a RI-ISI program as an alternate to the current CSA N285.4 and augmented programs for piping inspection. In response, a COG project was initiated to develop a best-fit methodology for the CANDU design and evaluate plant risk levels between current and RI-ISI inspection programs. EPRI RI-ISI was used as a starting point for methodology development. The effectiveness of current piping inspection programs in managing risk-significant locations was evaluated, and potential risk reductions associated with relocating or adding inspections were investigated.

  10. Application of ISI Web of Knowledge in Scientific Research%ISI Web of Knowledge在科学研究中的应用

    Institute of Scientific and Technical Information of China (English)

    王颖; 熊军洁; 王媛; 张晓东

    2009-01-01

    本文介绍了ISI Web of Knowledge平台的主要内容、功能以及在科学研究中的应用.ISI Web of Knowledge是为科研人员建立的研究平台,提供自然科学、社会科学、人文与艺术等领域的学术资源,通过将高质量的学术信息与搜索、分析等工具的有效整合,在很大程度上加速了科学发现与创新的进程,在科学研究中有重要应用.

  11. Improving Quantitative Precipitation Estimation via Data Fusion of High-Resolution Ground-based Radar Network and CMORPH Satellite-based Product

    Science.gov (United States)

    Cifelli, R.; Chen, H.; Chandrasekar, V.; Xie, P.

    2015-12-01

    A large number of precipitation products at multi-scales have been developed based upon satellite, radar, and/or rain gauge observations. However, how to produce optimal rainfall estimation for a given region is still challenging due to the spatial and temporal sampling difference of different sensors. In this study, we develop a data fusion mechanism to improve regional quantitative precipitation estimation (QPE) by utilizing satellite-based CMORPH product, ground radar measurements, as well as numerical model simulations. The CMORPH global precipitation product is essentially derived based on retrievals from passive microwave measurements and infrared observations onboard satellites (Joyce et al. 2004). The fine spatial-temporal resolution of 0.05o Lat/Lon and 30-min is appropriate for regional hydrologic and climate studies. However, it is inadequate for localized hydrometeorological applications such as urban flash flood forecasting. Via fusion of the Regional CMORPH product and local precipitation sensors, the high-resolution QPE performance can be improved. The area of interest is the Dallas-Fort Worth (DFW) Metroplex, which is the largest land-locked metropolitan area in the U.S. In addition to an NWS dual-polarization S-band WSR-88DP radar (i.e., KFWS radar), DFW hosts the high-resolution dual-polarization X-band radar network developed by the center for Collaborative Adaptive Sensing of the Atmosphere (CASA). This talk will present a general framework of precipitation data fusion based on satellite and ground observations. The detailed prototype architecture of using regional rainfall instruments to improve regional CMORPH precipitation product via multi-scale fusion techniques will also be discussed. Particularly, the temporal and spatial fusion algorithms developed for the DFW Metroplex will be described, which utilizes CMORPH product, S-band WSR-88DP, and X-band CASA radar measurements. In order to investigate the uncertainties associated with each

  12. ANALISA SITUASI KINI TENTANG ISI DAN PELAKSANAAN KEGIATAN GIZI DALAM "PRIMARY HEALTH CARE"

    Directory of Open Access Journals (Sweden)

    Soekartijah Martoadmodjo

    2012-11-01

    Full Text Available Dalam usaha untuk meningkatkan keadaan gizi masyarakat berpenghasilan rendah diberbagai negara di kawasan Asia Tenggara, termasuk Indonesia, langkah pertama ialah mengadakan penelitian mengenai isi dan pelaksanaan kegiatan gizi dengan pendekatan PHC yang telah dijalankan oleh negara bersangkutan. Penelitian ini mendapat bantuan dari WHO-SEARO.Sehubungan dengan itu telah dilakukan penelitian, dengan tujuan untuk memperoleh data saat ini, tentang isi dan pelaksanaan kegiatan gizi dengan pendekatan PHC pada organisasi kesehatan (Puskesmas-UKIA, UPGK-Kes, KB-Gizi dan PKMD di berbagai daerah, agar hasilnya dapat digunakan dalam meningkatkan pelaksanaan kegiatan gizi.Daerah terpilih ialah propinsi Jawa Barat, Jawa Tengah dan Sumatera Barat.

  13. Dynamic Changes of IsiA-Containing Complexes during Long-Term Iron Deficiency in Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Ma, Fei; Zhang, Xin; Zhu, Xi; Li, Tianpei; Zhan, Jiao; Chen, Hui; He, Chenliu; Wang, Qiang

    2017-01-09

    Iron stress-induced protein A (IsiA), a major chlorophyll-binding protein in the thylakoid membrane, is significantly induced under iron deficiency conditions. Using immunoblot analysis and 77 K fluorescence spectroscopy combined with sucrose gradient fractionation, we monitored dynamic changes of IsiA-containing complexes in Synechocystis sp. PCC 6803 during exposure to long-term iron deficiency. Within 3 days of exposure to iron deficiency conditions, the initially induced free IsiA proteins preferentially conjugated to PS I trimer to form IsiA18-PS I trimers, which serve as light energy collectors for efficiently transmitting energy to PS I. With prolonged iron deficiency, IsiA proteins assembled either into IsiA aggregates or into two other types of IsiA-PS I supercomplexes, namely IsiA-PS I high fluorescence supercomplex (IHFS) and IsiA-PS I low fluorescence supercomplex (ILFS). Further analysis revealed a role for IsiA as an energy dissipater in the IHFS and as an energy collector in the ILFS. The trimeric structure of PS I mediated by PsaL was found to be indispensable for the formation of IHFS/ILFS. Dynamic changes in IsiA-containing complexes in cyanobacteria during long-term iron deficiency may represent an adaptation to iron limitation stress for flexible light energy distribution, which balances electron transfer between PS I and PS II, thus minimizing photooxidative damage. Copyright © 2017 The Author. Published by Elsevier Inc. All rights reserved.

  14. ISI Proceedings分析工具Results Analysis的功能分析及检索实践%Function Analysis and Retrieval Practice about Result Analysis of ISI Proceedings

    Institute of Scientific and Technical Information of China (English)

    王园春

    2008-01-01

    本文以ISI Proceedings的科技版ISTP具体检索为倒,探讨了ISI Proceedings个性化服务的分析工具Results Analysis的功能和使用技巧,以及检索结果的信息分析和挖掘对用户的指导意义.

  15. Satellite Retrievals of Karenia brevis Harmful Algal Blooms in the West Florida Shelf Using Neural Networks and Comparisons with Other Techniques

    Directory of Open Access Journals (Sweden)

    Ahmed El-habashi

    2016-05-01

    Full Text Available We describe the application of a Neural Network (NN previously developed by us, to the detection and tracking, of Karenia brevis Harmful Algal Blooms (KB HABs that plague the coasts of the West Florida Shelf (WFS using Visible Infrared Imaging Radiometer Suite (VIIRS satellite observations. Previous approaches for the detection of KB HABs in the WFS primarily used observations from the Moderate Resolution Imaging Spectroradiometer Aqua (MODIS-A satellite. They depended on the remote sensing reflectance signal at the 678 nm chlorophyll fluorescence band (Rrs678 needed for both the normalized fluorescence height (nFLH and Red Band Difference algorithms (RBD currently used. VIIRS which has replaced MODIS-A, unfortunately does not have a 678 nm fluorescence channel so we customized the NN approach to retrieve phytoplankton absorption at 443 nm (aph443 using only Rrs measurements from existing VIIRS channels at 486, 551 and 671 nm. The aph443 values in these retrieved VIIRS images, can in turn be correlated to chlorophyll-a concentrations [Chla] and KB cell counts. To retrieve KB values, the VIIRS NN retrieved aph443 images are filtered by applying limiting constraints, defined by (i low backscatter at Rrs 551 nm and (ii a minimum aph443 value known to be associated with KB HABs in the WFS. The resulting filtered residual images, are then used to delineate and quantify the existing KB HABs. Comparisons with KB HABs satellite retrievals obtained using other techniques, including nFLH, as well as with in situ measurements reported over a four year period, confirm the viability of the NN technique, when combined with the filtering constraints devised, for effective detection of KB HABs.

  16. Cooperative and cognitive satellite systems

    CERN Document Server

    Chatzinotas, Symeon; De Gaudenzi, Riccardo

    2015-01-01

    Cooperative and Cognitive Satellite Systems provides a solid overview of the current research in the field of cooperative and cognitive satellite systems, helping users understand how to incorporate state-of-the-art communication techniques in innovative satellite network architectures to enable the next generation of satellite systems. The book is edited and written by top researchers and practitioners in the field, providing a comprehensive explanation of current research that allows users to discover future technologies and their applications, integrate satellite and terrestrial systems

  17. Orbit Determination of KOMPSAT-1 and Cryosat-2 Satellites Using Optical Wide-field Patrol Network (OWL-Net) Data with Batch Least Squares Filter

    Science.gov (United States)

    Lee, Eunji; Park, Sang-Young; Shin, Bumjoon; Cho, Sungki; Choi, Eun-Jung; Jo, Junghyun; Park, Jang-Hyun

    2017-03-01

    The optical wide-field patrol network (OWL-Net) is a Korean optical surveillance system that tracks and monitors domestic satellites. In this study, a batch least squares algorithm was developed for optical measurements and verified by Monte Carlo simulation and covariance analysis. Potential error sources of OWL-Net, such as noise, bias, and clock errors, were analyzed. There is a linear relation between the estimation accuracy and the noise level, and the accuracy significantly depends on the declination bias. In addition, the time-tagging error significantly degrades the observation accuracy, while the time-synchronization offset corresponds to the orbital motion. The Cartesian state vector and measurement bias were determined using the OWL-Net tracking data of the KOMPSAT-1 and Cryosat-2 satellites. The comparison with known orbital information based on two-line elements (TLE) and the consolidated prediction format (CPF) shows that the orbit determination accuracy is similar to that of TLE. Furthermore, the precision and accuracy of OWL-Net observation data were determined to be tens of arcsec and sub-degree level, respectively.

  18. Priority-based active queue management algorithm for satellite networks%一种基于优先级的卫星网络AQM算法

    Institute of Scientific and Technical Information of China (English)

    孙力娟; 谢慧婷; 肖甫; 叶晓国; 王汝传

    2011-01-01

    针对卫星网络大带宽、长时延、高误码等特点,结合控制理论,提出了一种基于优先级的卫星网络主动队列管理(active queue management,AQM)算法.首先,借鉴控制理论中比例-积分-微分(propertional-integral-derivative,PID)控制器设计方法计算总的报文丢弃概率;然后,针对IN和OUT两种不同优先级报文定义不同的丢弃概率,以实现不同优先级业务流量的区分服务.仿真实验表明,相对于低优先级流量,高优先级业务在保持高吞吐量的同时具有较低的报文丢失率,且整体队列长度抖动小,从而实现高优先级流量报文的有效保护.%Aimming at the characteristics of high bandwidth, long delay and high bit error ratio in satellite networks, a satellite network active queue management (AQM) algorithm based on prioity, which is integrated with control theory, is proposed. Firistly, based on the designing of the propertional-integral-derivative (PID) controller in control theory, a total probability of dropped messages is defined. Then, to differentiate between IN and OUT flows with different priorities, different probabilities of dropped messages are designed as well. Simulation results show that, compared with the case of flow with low priority, the proposed algorithm can effectively protect high priority flow by means of achieving a higher throughput with smaller jitter and low probability of dropped messages.

  19. [Henning v. Wistinghausen. Freimaurer in Estland. Ihre sozialstruktur am Beispiel der Revaler Loge "Isis" 1773-1820] / Paul Kaegbein

    Index Scriptorium Estoniae

    Kaegbein, Paul

    2007-01-01

    Arvustus: Henning v. Wistinghausen: Freimaurer in Estland. Ihre sozialstruktur am Beispiel der Revaler Loge "Isis" 1773-1820. In : Quatuor Coronati 42 (2005), lk. 287-305. Eesti vabamüürlaskonna sotsiaalsest koosseisust Tallinn loo̓i Isis (1773-1820) näitel

  20. ISI's Impact Factor as Misnomer: A Proposed New Measure To Assess Journal Impact.

    Science.gov (United States)

    Harter, Stephen P.; Nisonger, Thomas E.

    1997-01-01

    Discusses "impact factor," a measure of journal impact defined by the Institute of Scientific Information (ISI) and available in Journal Citation Reports. Argues that "impact factor" is misnamed and misused, suggesting an alternative name and interpretation of the measure, and proposes two new measures to assess the impact of…

  1. Comparing projections of future changes in runoff from hydrological and biome models in ISI-MIP

    NARCIS (Netherlands)

    Davie, J.C.S.; Falloon, P.D.; Kahana, R.; Dankers, R.; Betts, R.; Portmann, F.T.; Wisser, D.; Clark, D.B.; Ito, A.; Masaki, Y.; Nishina, K.; Fekete, B.; Tessler, Z.; Wada, Y.; Liu, X.; Tang, Q.; Hagemann, S.; Stacke, T.; Pavlick, R.; Schaphoff, S.; Gosling, S.N.; Franssen, W.H.P.; Arnell, N.

    2013-01-01

    Future changes in runoff can have important implications for water resources and flooding. In this study, runoff projections from ISI-MIP (Inter-sectoral Impact Model Inter-comparison Project) simulations forced with HadGEM2-ES bias-corrected climate data under the Representative Concentration Pathw

  2. Comparing projections of future changes in runoff from hydrological and biome models in ISI-MIP

    NARCIS (Netherlands)

    Davie, J. C. S.; Falloon, P. D.; Kahana, R.; Dankers, R.; Betts, R.; Portmann, F. T.; Wisser, D.; Clark, D. B.; Ito, A.; Masaki, Y.; Nishina, K.; Fekete, B.; Tessler, Z.; Wada, Y.; Liu, X.; Tang, Q.; Hagemann, S.; Stacke, T.; Pavlick, R.; Schaphoff, S.; Gosling, S. N.; Franssen, W.; Arnell, N.

    2013-01-01

    Future changes in runoff can have important implications for water resources and flooding. In this study, runoff projections from ISI-MIP (Inter-sectoral Impact Model Intercomparison Project) simulations forced with HadGEM2-ES bias-corrected climate data under the Representative Concentration Pathwa

  3. Spatial Diversity Scheme to Efficiently Cancel ISI and ICI in OFDM-OQAM Systems

    Directory of Open Access Journals (Sweden)

    Nizar Zorba

    2010-01-01

    removal while no ISI is generated. Moreover, the proposed system benefits from the multiuser gain through an opportunistic scheduler at the transmitter side to select the user with the best channel characteristics at each instant. The resultant scheme OQAM-OFDM-MIMO data rate is obtained in a closed form expression and proved to be higher than the classical CP-OFDM systems.

  4. Biomedical Applications of the Information-efficient Spectral Imaging Sensor (ISIS)

    Energy Technology Data Exchange (ETDEWEB)

    Gentry, S.M.; Levenson, R.

    1999-01-21

    The Information-efficient Spectral Imaging Sensor (ISIS) approach to spectral imaging seeks to bridge the gap between tuned multispectral and fixed hyperspectral imaging sensors. By allowing the definition of completely general spectral filter functions, truly optimal measurements can be made for a given task. These optimal measurements significantly improve signal-to-noise ratio (SNR) and speed, minimize data volume and data rate, while preserving classification accuracy. The following paper investigates the application of the ISIS sensing approach in two sample biomedical applications: prostate and colon cancer screening. It is shown that in these applications, two to three optimal measurements are sufficient to capture the majority of classification information for critical sample constituents. In the prostate cancer example, the optimal measurements allow 8% relative improvement in classification accuracy of critical cell constituents over a red, green, blue (RGB) sensor. In the colon cancer example, use of optimal measurements boost the classification accuracy of critical cell constituents by 28% relative to the RGB sensor. In both cases, optimal measurements match the performance achieved by the entire hyperspectral data set. The paper concludes that an ISIS style spectral imager can acquire these optimal spectral images directly, allowing improved classification accuracy over an RGB sensor. Compared to a hyperspectral sensor, the ISIS approach can achieve similar classification accuracy using a significantly lower number of spectral samples, thus minimizing overall sample classification time and cost.

  5. Ranking Leading Econometrics Journals Using Citations Data from ISI and RePEc

    Directory of Open Access Journals (Sweden)

    Chia-Lin Chang

    2013-11-01

    Full Text Available The paper focuses on the robustness of rankings of academic journal quality and research impact of 10 leading econometrics journals taken from the Thomson Reuters ISI Web of Science (ISI Category of Economics, using citations data from ISI and the highly accessible Research Papers in Economics (RePEc database that is widely used in economics, finance and related disciplines. The journals are ranked using quantifiable static and dynamic Research Assessment Measures (RAMs, with 15 RAMs from ISI and five RAMs from RePEc. The similarities and differences in various RAMs, which are based on alternative weighted and unweighted transformations of citations, are highlighted to show which RAMs are able to provide informational value relative to others. The RAMs include the impact factor, mean citations and non-citations, journal policy, number of high quality papers, and journal influence and article influence. The paper highlights robust rankings based on the harmonic mean of the ranks of 20 RAMs, which in some cases are closely related. It is shown that emphasizing the most widely-used RAM, the two-year impact factor of a journal, can lead to a distorted evaluation of journal quality, impact and influence relative to the harmonic mean of the ranks. Some suggestions regarding the use of the most informative RAMs are also given.

  6. Early Detection of Autism Spectrum Disorder in Young isiZulu-Speaking Children in South Africa

    Science.gov (United States)

    Chambers, Nola J.; Wetherby, Amy M.; Stronach, Sheri T.; Njongwe, Nonyameko; Kauchali, Shuaib; Grinker, Richard R.

    2017-01-01

    Culturally appropriate tools are needed for detecting symptoms of autism spectrum disorder in young South African children. The objectives of this study were to (1) adapt and translate into isiZulu existing measures for detecting early signs of autism spectrum disorder, (2) use the measures to characterize and compare behavioural profiles of young…

  7. A global map of science based on the ISI subject categories

    NARCIS (Netherlands)

    Leydesdorff, L.; Rafols, I

    2009-01-01

    The decomposition of scientific literature into disciplinary and subdisciplinary structures is one of the core goals of scientometrics. How can we achieve a good decomposition? The ISI subject categories classify journals included in the Science Citation Index (SCI). The aggregated journal-journal c

  8. Nonlinear Trellis Description for Convolutionally Encoded Transmission Over ISI-channels with Applications for CPM

    CERN Document Server

    Schuh, Fabian

    2012-01-01

    In this paper we propose a matched decoding scheme for convolutionally encoded transmission over intersymbol interference (ISI) channels and devise a nonlinear trellis description. As an application we show that for coded continuous phase modulation (CPM) using a non-coherent receiver the number of states of the super trellis can be significantly reduced by means of a matched non-linear trellis encoder.

  9. Simulations of chopper jitter at the LET neutron spectrometer at the ISIS TS2

    DEFF Research Database (Denmark)

    Klenø, Kaspar Hewitt; Lefmann, Kim; Willendrup, Peter Kjær

    2014-01-01

    The effect of uncertainty in chopper phasing (jitter) has been investigated for the high-resolution time-of-flight spectrometer LET at the ISIS second target station. The investigation is carried out using virtual experiments, with the neutron simulation package McStas, where the chopper jitter i...

  10. Making up the "Ummah": The Rhetoric of ISIS as Public Pedagogy

    Science.gov (United States)

    Low, Remy

    2016-01-01

    In this article, the author submits that the push for moderation and social cohesion through deradicalization is an inadequate response to violence inspired by the Islamic State in Iraq and Syria (ISIS) because it elides the political disaffections to which the group speaks. In advancing this argument, the author suggests that the rhetoric of ISIS…

  11. The ISI Classroom Observation System: Examining the Literacy Instruction Provided to Individual Students

    Science.gov (United States)

    Connor, Carol McDonald; Morrison, Frederick J.; Fishman, Barry J.; Ponitz, Claire Cameron; Glasney, Stephanie; Underwood, Phyllis S.; Piasta, Shayne B.; Crowe, Elizabeth Coyne; Schatschneider, Christopher

    2009-01-01

    The Individualizing Student Instruction (ISI) classroom observation and coding system is designed to provide a detailed picture of the classroom environment at the level of the individual student. Using a multidimensional conceptualization of the classroom environment, foundational elements (teacher warmth and responsiveness to students, classroom…

  12. Frontiers of muon spectroscopy—25 years of muon science at ISIS

    Science.gov (United States)

    Cottrell, Stephen

    2013-12-01

    The ISIS muon source developed with support from the European Community (EC) and groups at Grenoble, Parma, Uppsala and Munich in the late 1980s, with a single instrument providing many scientists with their first opportunity to explore the unique capabilities of muon spectroscopy. The timing was opportune, as the muon technique was making an important contribution to the study of the then recently discovered cuprate high T c superconductors. The ISIS user community developed rapidly over subsequent years, with the technique finding a broad range of applications in condensed matter physics, materials science and chemistry. The single instrument was hugely oversubscribed, and the importance of the technique was recognized in 1993 with a further grant from the EC to develop the triple beamline facility that is currently available at ISIS. During 2009 the suite of spectrometers available at the facility received a major upgrade, with the Science and Technology Facilities Council funding the development of a 5 T high field instrument that has enabled entirely new applications of muon spectroscopy to be explored. The facility continues to flourish, with a strong user community exploiting the technique to support research across an increasingly broad range of subject areas. Condensed matter science continues to be a major area of interest, with applications including semiconductors and dielectrics, superconductors, magnetism, interstitial diffusion and charge transport. Recently, however, molecular science and radical chemistry have become prominent in the ISIS programme, applications where the availability of high magnetic fields is frequently vital to the success of the experiments. For ISIS, 23 March 2012 marked a significant milestone, it being 25 years since muons were first produced at the facility for research in condensed matter and molecular science. To celebrate, the ISIS muon group organized a science symposium with the theme 'Frontiers of Muon Spectroscopy

  13. Future communications satellite applications

    Science.gov (United States)

    Bagwell, James W.

    1992-01-01

    The point of view of the research is made through the use of viewgraphs. It is suggested that future communications satellite applications will be made through switched point to point narrowband communications. Some characteristics of which are as follows: small/low cost terminals; single hop communications; voice compatible; full mesh networking; ISDN compatible; and possible limited use of full motion video. Some target applications are as follows: voice/data networks between plants and offices in a corporation; data base networking for commercial and science users; and cellular radio internodal voice/data networking.

  14. The comprehension and production of quantifiers in isiXhosa-speaking Grade 1 learners

    Directory of Open Access Journals (Sweden)

    Joanine Nel

    2016-05-01

    Full Text Available Background: Quantifiers form part of the discourse-internal linguistic devices that children need to access and produce narratives and other classroom discourse. Little is known about the development - especially the prodiction - of quantifiers in child language, specifically in speakers of an African language.Objectives: The study aimed to ascertain how well Grade 1 isiXhosa first language (L1 learners perform at the beginning and at the end of Grade 1 on quantifier comprehension and production tasks.Method: Two low socioeconomic groups of L1 isiXhosa learners with either isiXhosa or English as language of learning and teaching (LOLT were tested in February and November of their Grade 1 year with tasks targeting several quantifiers.Results: The isiXhosa LOLT group comprehended no/none, any and all fully either in February or then in November of Grade 1, and they produced all assessed quantifiers in February of Grade 1. For the English LOLT group, neither the comprehension nor the production of quantifiers was mastered by the end of Grade 1, although there was a significant increase in both their comprehension and production scores.Conclusion: The English LOLT group made significant progress in comprehension and production of quantifiers, but still performed worse than peers who had their L1 as LOLT. Generally, children with no or very little prior knowledge of the LOLT need either, (1 more deliberate exposure to quantifier-rich language or, (2 longer exposure to general classroom language before quantifiers can be expected to be mastered sufficiently to allow access to quantifier-related curriculum content.Keywords: quantifiers; isiXhosa; Grade 1

  15. Translation and validation of a patient satisfaction survey: The isiXhosa version

    Directory of Open Access Journals (Sweden)

    Tania Steyl

    2013-01-01

    Full Text Available Background: Although the use of surveys has been supported for assessing understanding of health care service quality, it could also be argued that their main function is to quantify perceptions. The importance of assessing patient satisfaction in individuals’ own language has been highlighted in research. However, important culture-specific differences can be revealed during the adaptation process of a scale, and if not attended to can influence the validity ofthe scale.Objectives: The aim of this study was to assess the validity and reliability of the isiXhosa version of the Patient Survey for Quality of Care (PSQC in primary health care (PHC facilities in a selected district in the Western Cape, South Africa.Method: The PSQC was translated into isiXhosa by two independant translators and the translated back into English by a third translator. All three translators reviewed the back translation. Face and content validity of the scale were assessed. Fifteen isiXhosa-speaking clients with type 2 diabetes mellitus who had a mean age of 62.27 years (SD 10.33 and came from a randomly selected community health centre participated in the test-retest reliability.Results: Internal consistency of the scale was good (Cronbach alpha 0.70. Alpha values of individual items relating to quality of care as well as items flagged for inferior service quality were between 0.772 and 1.000, indicating good to high internal consistency.Conclusion: Results of this study indicated that the isiXhosa version of the PSQC was as reliable as the English version. It can be implemented at PHC level to assess isiXhosa-speaking patients’ satisfaction with health care services.

  16. Translation and validation of a patient satisfaction survey: The isiXhosa version

    Directory of Open Access Journals (Sweden)

    Tania Steyl

    2013-01-01

    Full Text Available Background: Although the use of surveys has been supported for assessing understanding of health care service quality, it could also be argued that their main function is to quantify perceptions. The importance of assessing patient satisfaction in individuals’ own language has been highlighted in research. However, important culture-specific differences can be revealed during the adaptation process of a scale, and if not attended to can influence the validity ofthe scale.Objectives: The aim of this study was to assess the validity and reliability of the isiXhosa version of the Patient Survey for Quality of Care (PSQC in primary health care (PHC facilities in a selected district in the Western Cape, South Africa.Method: The PSQC was translated into isiXhosa by two independant translators and the translated back into English by a third translator. All three translators reviewed the back translation. Face and content validity of the scale were assessed. Fifteen isiXhosa-speaking clients with type 2 diabetes mellitus who had a mean age of 62.27 years (SD 10.33 and came from a randomly selected community health centre participated in the test-retest reliability.Results: Internal consistency of the scale was good (Cronbach alpha 0.70. Alpha values of individual items relating to quality of care as well as items flagged for inferior service quality were between 0.772 and 1.000, indicating good to high internal consistency.Conclusion: Results of this study indicated that the isiXhosa version of the PSQC was as reliable as the English version. It can be implemented at PHC level to assess isiXhosa-speaking patients’ satisfaction with health care services.

  17. Study on Dynamic Resource Management about the Satellite Communication Network%卫星通信网络资源管理研究

    Institute of Scientific and Technical Information of China (English)

    贺祥

    2016-01-01

    In this paper we study the capacity request queue scheduling mechanism based on the distinct service QoS in view of RCST terminals;In view of the network control center,we study a dynamic resource management based on volume change trend prediction method. The concolusions of this paper can be used in the satellite communication network between terminal and centre station in interactive business requests and resource allocation.%本文针对RCST终端,研究了基于区分服务QoS的容量请求排队调度机制;针对网络控制中心,研究了一种基于业务量变化趋势预测的动态资源管理方法,可用于IP化卫星通信网络中终端与中心站之间交互式的业务请求与资源分配。

  18. High altitude clouds impacts on the design of optical feeder link and optical ground station network for future broadband satellite services

    Science.gov (United States)

    Poulenard, S.; Ruellan, M.; Roy, B.; Riédi, J.; Parol, F.; Rissons, A.

    2014-03-01

    Optical links at 1.55μm are envisaged to cope with the increasing capacity demand from geostationary telecom satellite operators without the need of Radio Frequency (RF) coordination. Due to clouds blockages, site diversity techniques based on a network of Optical Ground Stations (OGS) are necessary to reach the commonly required link availability (e.g. 99.9% over the year). Evaluation of the N Optical Ground Station Network (N-OGSN) availability is based on Clouds Masks (CMs) and depends on the clouds attenuation taken in the optical communication budget link. In particular, low attenuation of high semitransparent clouds (i.e. cirrus) could be incorporated into the budget link at the price of larger or more powerful optical terminals. In this paper, we present a method for the calibration of the attenuation at 1.55 μm of high semitransparent clouds. We perform OGS localization optimization in Europe and we find that the incorporation of thin cirrus attenuation in the budget link reduces by 20% the number of handover (i.e. switches OGS) and the handover rate. It is also shown that the minimum number of station required in Europe to reach 99.9% link availability is 10 to 11. When the zone of research is enlarged the Africa, this number is reduced to 3 to 4.

  19. 一种MF—TDMA卫星通信混合拓扑网络分析%Analysis of an MF-TDMA Hybrid Topology Satellite Communication Network

    Institute of Scientific and Technical Information of China (English)

    郝学坤

    2012-01-01

    在分析多频时分多址(MF—TDMA)卫星通信体制特点和发展需求的基础上,提出了一种基于MF-TDMA体制构建多星状与网状一体化混合拓扑网络的方法。首先给出了所提出的混合拓扑网络的特点和应用场景,然后设计了MF—TDMA混合网的多载波帧结构并分析了同步控制技术和各类载波与时隙的配置,最后给出了星状、网状用户地球站间的通信流程和使用载波时隙信道资源的方法。%A design method of multi-star and mesh hybrid topology MF-TDMA satellite communication network is proposed after analysis MF-TDMA characteristic and development. Firstly, the hybrid topology network specialty and application scene is analyzed. Then with the help of MF-TDMA technology the multi-carrier frame structure and the method of synchronization control and carrier slot deployment is proposed. At last, the interactive process of star and mesh communication station and the method of slot channel resource management is presented.

  20. ISI Web of KnowledgeSM:A Web-based Integrated Retrieval Platform%ISI Web of Knowledge集成检索平台评析

    Institute of Scientific and Technical Information of China (English)

    陈朋

    2004-01-01

    本文从资源整合与集成检索的角度出发,对ISI Web of KnowledgeSM平台的集成化信息检索机制作了一个全面的解析;同时指出其优势与不足之处,希望为我国图书情报机构打造成熟的、满足用户方便、快捷获取所需信息的检索平台提供一点借鉴.

  1. Top-of-the-atmosphere shortwave flux estimation from satellite observations: an empirical neural network approach applied with data from the A-train constellation

    Science.gov (United States)

    Gupta, Pawan; Joiner, Joanna; Vasilkov, Alexander; Bhartia, Pawan K.

    2016-07-01

    Estimates of top-of-the-atmosphere (TOA) radiative flux are essential for the understanding of Earth's energy budget and climate system. Clouds, aerosols, water vapor, and ozone (O3) are among the most important atmospheric agents impacting the Earth's shortwave (SW) radiation budget. There are several sensors in orbit that provide independent information related to these parameters. Having coincident information from these sensors is important for understanding their potential contributions. The A-train constellation of satellites provides a unique opportunity to analyze data from several of these sensors. In this paper, retrievals of cloud/aerosol parameters and total column ozone (TCO) from the Aura Ozone Monitoring Instrument (OMI) have been collocated with the Aqua Clouds and Earth's Radiant Energy System (CERES) estimates of total reflected TOA outgoing SW flux (SWF). We use these data to develop a variety of neural networks that estimate TOA SWF globally over ocean and land using only OMI data and other ancillary information as inputs and CERES TOA SWF as the output for training purposes. OMI-estimated TOA SWF from the trained neural networks reproduces independent CERES data with high fidelity. The global mean daily TOA SWF calculated from OMI is consistently within ±1 % of CERES throughout the year 2007. Application of our neural network method to other sensors that provide similar retrieved parameters, both past and future, can produce similar estimates TOA SWF. For example, the well-calibrated Total Ozone Mapping Spectrometer (TOMS) series could provide estimates of TOA SWF dating back to late 1978.

  2. Postgraduate Students' Experiences and Attitudes Towards isiZulu as a Medium of Instruction at the University of KwaZulu-Natal

    Science.gov (United States)

    Nkosi, Zinhle Primrose

    2014-01-01

    IsiZulu is one of the 11 official languages of South Africa and has the highest number of speakers in the country. While the South African Language Policy for Higher Education (2002) emphasizes the need to use African languages at universities, not many universities' isiZulu-speaking students prefer to be taught in isiZulu. Research has…

  3. Wave activity (planetary, tidal throughout the middle atmosphere (20-100km over the CUJO network: Satellite (TOMS and Medium Frequency (MF radar observations

    Directory of Open Access Journals (Sweden)

    A. H. Manson

    2005-02-01

    Full Text Available Planetary and tidal wave activity in the tropopause-lower stratosphere and mesosphere-lower thermosphere (MLT is studied using combinations of ground-based (GB and satellite instruments (2000-2002. The relatively new MFR (medium frequency radar at Platteville (40° N, 105° W has provided the opportunity to create an operational network of middle-latitude MFRs, stretching from 81° W-142° E, which provides winds and tides 70-100km. CUJO (Canada U.S. Japan Opportunity comprises systems at London (43° N, 81° W, Platteville (40° N, 105° W, Saskatoon (52° N, 107° W, Wakkanai (45° N, 142° E and Yamagawa (31° N, 131° E. It offers a significant 7000-km longitudinal sector in the North American-Pacific region, and a useful range of latitudes (12-14° at two longitudes. Satellite data mainly involve the daily values of the total ozone column measured by the Earth Probe (EP TOMS (Total Ozone Mapping Spectrometer and provide a measure of tropopause-lower stratospheric planetary wave activity, as well as ozone variability.

    Climatologies of ozone and winds/tides involving frequency versus time (wavelet contour plots for periods from 2-d to 30-d and the interval from mid 2000 to 2002, show that the changes with altitude, longitude and latitude are very significant and distinctive. Geometric-mean wavelets for the region of the 40° N MFRs demonstrate occasions during the autumn, winter and spring months when there are similarities in the spectral features of the lower atmosphere and at mesopause (85km heights. Both direct planetary wave (PW propagation into the MLT, nonlinear PW-tide interactions, and disturbances in MLT tides associated with fluctuations in the ozone forcing are considered to be possible coupling processes. The complex horizontal wave numbers of the longer period oscillations are provided in frequency contour plots for the TOMS satellite data to demonstrate the differences between lower atmospheric

  4. Wave activity (planetary, tidal) throughout the middle atmosphere (20-100km) over the CUJO network: Satellite (TOMS) and Medium Frequency (MF) radar observations

    Science.gov (United States)

    Manson, A. H.; Meek, C. E.; Chshyolkova, T.; Avery, S. K.; Thorsen, D.; MacDougall, J. W.; Hocking, W.; Murayama, Y.; Igarashi, K.

    2005-02-01

    Planetary and tidal wave activity in the tropopause-lower stratosphere and mesosphere-lower thermosphere (MLT) is studied using combinations of ground-based (GB) and satellite instruments (2000-2002). The relatively new MFR (medium frequency radar) at Platteville (40° N, 105° W) has provided the opportunity to create an operational network of middle-latitude MFRs, stretching from 81° W-142° E, which provides winds and tides 70-100km. CUJO (Canada U.S. Japan Opportunity) comprises systems at London (43° N, 81° W), Platteville (40° N, 105° W), Saskatoon (52° N, 107° W), Wakkanai (45° N, 142° E) and Yamagawa (31° N, 131° E). It offers a significant 7000-km longitudinal sector in the North American-Pacific region, and a useful range of latitudes (12-14°) at two longitudes. Satellite data mainly involve the daily values of the total ozone column measured by the Earth Probe (EP) TOMS (Total Ozone Mapping Spectrometer) and provide a measure of tropopause-lower stratospheric planetary wave activity, as well as ozone variability. Climatologies of ozone and winds/tides involving frequency versus time (wavelet) contour plots for periods from 2-d to 30-d and the interval from mid 2000 to 2002, show that the changes with altitude, longitude and latitude are very significant and distinctive. Geometric-mean wavelets for the region of the 40° N MFRs demonstrate occasions during the autumn, winter and spring months when there are similarities in the spectral features of the lower atmosphere and at mesopause (85km) heights. Both direct planetary wave (PW) propagation into the MLT, nonlinear PW-tide interactions, and disturbances in MLT tides associated with fluctuations in the ozone forcing are considered to be possible coupling processes. The complex horizontal wave numbers of the longer period oscillations are provided in frequency contour plots for the TOMS satellite data to demonstrate the differences between lower atmospheric and MLT wave motions and their

  5. The effect of sample size on fresh plasma thromboplastin ISI determination

    DEFF Research Database (Denmark)

    Poller, L; Van Den Besselaar, A M; Jespersen, J;

    1999-01-01

    The possibility of reduction of numbers of fresh coumarin and normal plasmas has been studied in a multicentre manual prothrombin (PT) calibration of high international sensitivity index (ISI) rabbit and low ISI human reference thromboplastins at 14 laboratories. The number of calibrant plasmas...... was reduced progressively by a computer program which generated random numbers to provide 1000 different selections for each reduced sample at each participant laboratory. Results were compared with those of the full set of 20 normal and 60 coumarin plasma calibrations. With the human reagent, 20 coumarins...... and seven normals still achieved the W.H.O. precision limit (3% CV of the slope), but with the rabbit reagent reduction coumarins with 17 normal plasmas led to unacceptable CV. Little reduction of numbers from the full set of 80 fresh plasmas appears advisable. For maximum confidence, when calibrating...

  6. From ISIS to CouchDB: Databases and Data Models for Bibliographic Records

    Directory of Open Access Journals (Sweden)

    Luciano Ramalho

    2011-04-01

    Full Text Available For decades bibliographic data has been stored in non-relational databases, and thousands of libraries in developing countries still use ISIS databases to run their OPACs. Fast forward to 2010 and the NoSQL movement has shown that non-relational databases are good enough for Google, Amazon.com and Facebook. Meanwhile, several Open Source NoSQL systems have appeared. This paper discusses the data model of one class of NoSQL products, semistructured, document-oriented databases exemplified by Apache CouchDB and MongoDB, and why they are well-suited to collective cataloging applications. Also shown are the methods, tools, and scripts used to convert, from ISIS to CouchDB, bibliographic records of LILACS, a key Latin American and Caribbean health sciences index operated by the Pan-American Health Organization.

  7. Some ISIS-Software History and Technical Background on the new FOSS Integrated Library System ABCD

    Directory of Open Access Journals (Sweden)

    Egbert de Smet

    2010-02-01

    Full Text Available While free and open source software is gaining momentum in library automation, it is still not a trivial event to launch a full-blown integrated library system (ILS, given today's high demands on such library systems. In this article we describe the ISIS-software origins of the newly launched ABCD-software for which there is a morethan-average interest in many parts of the libraries and information communities in the developing world. Many — especially younger — librarians in the West have never heard about ISIS, its relevance and its technological concepts, so we will try to shed some light on this in order for librarians to better judge the meaning of the ABCD software for international librarianship and — why not — perhaps even for their own purposes.

  8. Spike trains in Hodgkin-Huxley model and ISIs of acupuncture manipulations

    Energy Technology Data Exchange (ETDEWEB)

    Wang Jiang [School of Electrical and Automation Engineering, Tianjin University, Tianjin 300072 (China)], E-mail: jiangwang@tju.edu.cn; Si Wenjie; Che Yanqiu; Fei Xiangyang [School of Electrical and Automation Engineering, Tianjin University, Tianjin 300072 (China)

    2008-05-15

    The Hodgkin-Huxley equations (HH) are parameterized by a number of parameters and shows a variety of qualitatively different behaviors depending on the parameter values. Under stimulation of an external periodic voltage, the ISIs (interspike intervals) of a HH model are investigated in this work, while the frequency of the voltage is taken as the controlling parameter. As well-known, the science of acupuncture and moxibustion is an important component of Traditional Chinese Medicine with a long history. Although there are a number of different acupuncture manipulations, the method for distinguishing them is rarely investigated. With the idea of ISI, we study the electrical signal time series at the spinal dorsal horn produced by three different acupuncture manipulations in Zusanli point and present an effective way to distinguish them.

  9. An alternating periodic-chaotic ISI sequence of HH neuron under external sinusoidal stimulus

    Institute of Scientific and Technical Information of China (English)

    Jin Wu-Yin; Xu Jian-Xue; Wu Ying; Hong Ling

    2004-01-01

    A study of Hodgkin-Huxley (HH) neuron under external sinusoidal excited stimulus is presented in this paper. As is well known, the stimulus frequency is to be considered as a bifurcate parameter, and numerous phenomena, such as synchronization, period, and chaos appear alternatively with the changing of the stimulus frequency. For the stimulus frequency less than 2fB (fB being the base frequency in this paper), the simulation results demonstrate that the single HH neuron could completely convey the sinusoidal signal in anti-phase into interspike interval (ISI) sequences. We also report, perhaps for the first time, another kind of phenomenon, the beat phenomenon, which exists in the phase dynamics of the ISI sequences of the HH neuron stimulated by a sinusoidal current. It is shown furthermore that intermittent transition results in the general route to chaos.

  10. A Convex Optimization Based Demodulation and Equalization Scheme for Differential Impulse Radio UWB Systems with ISI

    CERN Document Server

    Ma, Xudong

    2008-01-01

    In this paper, we consider the demodulation and equalization problem of differential Impulse Radio (IR) Ultra-WideBand (UWB) Systems with Inter-Symbol-Interference (ISI). The differential IR UWB systems have been extensively discussed recently. The advantage of differential IR UWB systems include simple receiver frontend structure. One challenge in the demodulation and equalization of such systems with ISI is that the systems have a rather complex model. The input and output signals of the systems follow a second-order Volterra model. Furthermore, the noise at the output is data dependent. In this paper, we propose a reduced-complexity joint demodulation and equalization algorithm. The algorithm is based on reformulating the nearest neighborhood decoding problem into a mixed quadratic programming and utilizing a semi-definite relaxation. The numerical results show that the proposed demodulation and equalization algorithm has low computational complexity, and at the same time, has almost the same error probabi...

  11. Lexical development of noun and predicate comprehension and production in isiZulu

    Directory of Open Access Journals (Sweden)

    Ramona Kunene Nicolas

    2016-05-01

    Full Text Available This study seeks to investigate the development of noun and predicate comprehension and production in isiZulu-speaking children between the ages of 25 and 36 months. It compares lexical comprehension and production in isiZulu, using an Italian developed and validated vocabulary assessment tool: The Picture Naming Game (PiNG developed by Bello, Giannantoni, Pettenati, Stefanini and Caselli (2012. The PiNG tool includes four subtests, one each for subnoun comprehension (NC, noun production (NP, predicate comprehension (PC, and predicate production (PP. Children are shown these lexical items and then asked to show comprehension and produce certain lexical items. After adaptation into the South African context, the adapted version of PiNG was used to directly assess the lexical development of isiZulu with the three main objectives to (1 test the efficiency of the adaptation of a vocabulary tool to measure isiZulu comprehension and production development, (2 test previous findings done in many cross-linguistic comparisons that have found that both comprehension and production performance increase with age for a lesser-studied language, and (3 present our findings around the comprehension and production of the linguistic categories of nouns and predicates. An analysis of the results reported in this study show an age effect throughout the entire sample. Across all the age groups, the comprehension of the noun and predicate subtests was better performed than the production of noun and predicate subtests. With regard to lexical items, the responses of children showed an influence of various factors, including the late acquisition of items, possible problems with stimuli presented to them, and the possible input received by the children from their home environment.

  12. ISI-MIP: The Inter-Sectoral Impact Model Intercomparison Project

    Science.gov (United States)

    Huber, V.; Dahlemann, S.; Frieler, K.; Piontek, F.; Schewe, J.; Serdeczny, O.; Warszawski, L.

    2013-12-01

    The Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP) aims to synthesize the state-of-the-art knowledge of climate change impacts at different levels of global warming. The project's experimental design is formulated to distinguish the uncertainty introduced by the impact models themselves, from the inherent uncertainty in the climate projections and the variety of plausible socio-economic futures. The unique cross-sectoral scope of the project provides the opportunity to study cascading effects of impacts in interacting sectors and to identify regional 'hot spots' where multiple sectors experience extreme impacts. Another emphasis lies on the development of novel metrics to describe societal impacts of a warmer climate. We briefly outline the methodological framework, and then present selected results of the first, fast-tracked phase of ISI-MIP. The fast track brought together 35 global impact models internationally, spanning five sectors across human society and the natural world (agriculture, water, natural ecosystems, health and coastal infrastructure), and using the latest generation of global climate simulations (RCP projections from the CMIP5 archive) and socioeconomic drivers provided within the SSP process. We also introduce the second phase of the project, which will enlarge the scope of ISI-MIP by encompassing further impact sectors (e.g., forestry, fisheries, permafrost) and regional modeling approaches. The focus for the next round of simulations will be the validation and improvement of models based on historical observations and the analysis of variability and extreme events. Last but not least, we discuss the longer-term objective of ISI-MIP to initiate a coordinated, ongoing impact assessment process, driven by the entire impact community and in parallel with well-established climate model intercomparisons (CMIP).

  13. Lexical development of noun and predicate comprehension and production in isiZulu.

    Science.gov (United States)

    Nicolas, Ramona Kunene; Ahmed, Saaliha

    2016-07-28

    This study seeks to investigate the development of noun and predicate comprehension and production in isiZulu-speaking children between the ages of 25 and 36 months. It compares lexical comprehension and production in isiZulu, using an Italian developed and validated vocabulary assessment tool: The Picture Naming Game (PiNG) developed by Bello, Giannantoni, Pettenati, Stefanini and Caselli (2012). The PiNG tool includes four subtests, one each for subnoun comprehension (NC), noun production (NP), predicate comprehension (PC), and predicate production (PP). Children are shown these lexical items and then asked to show comprehension and produce certain lexical items. After adaptation into the South African context, the adapted version of PiNG was used to directly assess the lexical development of isiZulu with the three main objectives to (1) test the efficiency of the adaptation of a vocabulary tool to measure isiZulu comprehension and production development, (2) test previous findings done in many cross-linguistic comparisons that have found that both comprehension and production performance increase with age for a lesser-studied language, and (3) present our findings around the comprehension and production of the linguistic categories of nouns and predicates. An analysis of the results reported in this study show an age effect throughout the entire sample. Across all the age groups, the comprehension of the noun and predicate subtests was better performed than the production of noun and predicate subtests. With regard to lexical items, the responses of children showed an influence of various factors, including the late acquisition of items, possible problems with stimuli presented to them, and the possible input received by the children from their home environment.

  14. Nonlinear ISI cancellation in VSSB Nyquist-SCM system with symbol pre-distortion

    Science.gov (United States)

    Liu, Na; Ju, Cheng; Chen, Xue

    2015-03-01

    We propose and experimentally demonstrate a 40-Gbps virtual single sideband (VSSB) Nyquist-subcarrier-modulation (Nyquist-SCM) direct detection scheme with symbol pre-distortion to mitigate the nonlinear inter-symbol interference (ISI) caused by dispersion and square-law detection. The experimental result shows that 2.6-dB receiver sensitivity improvement is obtained after 100-km standard single mode fiber (SSMF) transmission.

  15. Satellite Communications: The Indian Scenario

    Directory of Open Access Journals (Sweden)

    Dr. Ranjit Singh

    2014-05-01

    Full Text Available India has launched as many as 73 Indian satellites as of today since its first attempt in 1975. Besides serving traditional markets of telephony and broadcasting, satellites are on the frontiers of advanced applications as telemedicine, distance learning, environment monitoring, remote sensing, and so on. Satellite systems are optimized for services such as Internet access, virtual private networks and personal access. Costs have been coming down in recent years to the point where satellite broadband is becoming competitive. This article is an attempt to view this important topic from Indian perspective. India’s Project GAGAN, GPS Aided Geo Augmented Navigation is discussed.

  16. Advanced Communications Technology Satellite (ACTS)

    Science.gov (United States)

    Gedney, Richard T.; Schertler, Ronald J.

    1989-01-01

    The NASA Advanced Communications Technology Satellite (ACTS) was conceived to help maintain U.S. leadership in the world's communications-satellite market. This experimental satellite is expected to be launched by NASA in 1992 and to furnish the technology necessary for establishing very small aperture terminal digital networks which provide on-demand full-mesh connectivity, and 1.544-MBPS services with only a single hop. Utilizing on-board switching and processing, each individual voice or data circuit can be separately routed to any location in the network. This paper provides an overview of the ACTS and discusses the value of the technology for future communications systems.

  17. Perilaku Masyarakat Kabupaten Belitung Terhadap Layanan Isi Ulang Pulsa Telepon Seluler Elektronik

    Directory of Open Access Journals (Sweden)

    Kasmad Ariansyah

    2012-12-01

    Full Text Available Telepon seluler prabayar merupakan telepon seluler yang pembayaran pulsanya dilakukan diawal dengan membeli voucher pulsa dengan nominal tertentu. Pada awalnya pulsa telepon seluler prabayar hanya dijual dalam bentuk kartu berbahan kertas dengan kode-kode tertentu diatasnya.  Sekarang kita sudah menemui layanan isi ulang pulsa secara elektronik. Penggunaan voucher telepon berbentuk fisik yang berbahan kertas, tidak sejalan dengan program pemerintah yang sedang menggalakkan paperless. Terlebih Jumlah pelanggan seluler di Indonesia yang demikian besar, pada awal 2012 ATSI mencatat  sekitar 240 juta orang Indonesia menggunakan layanan seluler dan sebagian besarnya adalah pelanggan prabayar. Penelitian ini bertujuan mendapatkan gambaran perilaku dan konstruk-konstruk yang mempengaruhi masyarakat Kabupaten Belitung terhadap layanan isi ulang pulsa telepon seluler secara elektronik dan diharapkan dapat menjadi salah satu masukan bagi penyusunan strategi meningkatkan adopsi layanan isi ulang secara elektronik. Temuan dari penelitian ini adalah konstruk perceived of usefullness dan personal innovativeness secara positif dan signifikan mempengaruhi minat berperilaku dalam menggunakan voucher elektronik pada masyarakat di Kabupaten Belitung. Sedangkan dua konstruk lainnya yaitu social influence dan perceived cost pengaruhnya tidak signifikan.

  18. ISI Web of Knowledge平台新增功能在科研中的利用分析%Brief Talk on Retrieval Functions of New Edition ISI Web of Knowledge

    Institute of Scientific and Technical Information of China (English)

    谢华玲; 郑菲; 陈朝晖

    2009-01-01

    介绍新版ISI Web of Knowledge平台在2008年10月系统升级后的新增功能,重点推介Scientific WebPlus、Citation Map和ResearcherID的使用方法及在科研中的利用,为科研人员和图书情报人员使用新版ISI Web of Knowledge平台提供参考.

  19. Polish and European SST Assets: the Solaris-Panoptes Global Network of Robotic Telescopes and the Borowiec Satellite Laser Ranging System

    Science.gov (United States)

    Konacki, M.; Lejba, P.; Sybilski, P.; Pawłaszek, R.; Kozłowski, S.; Suchodolski, T.; Litwicki, M.; Kolb, U.; Burwitz, V.; Baader, J.; Groot, P.; Bloemen, S.; Ratajczak, M.; Helminiak, K.; Borek, R.; Chodosiewicz, P.

    2016-09-01

    We present the assets of the Nicolaus Copernicus Astronomical Center, Space Research Center (both of the Polish Academy of Sciences), two Polish companies Sybilla Technologies, Cillium Engineering and a non-profit research foundation Baltic Institute of Technology. These assets are enhanced by telescopes belonging to The Open University (UK), the Max Planck Institute for Extraterrestrial Physics and in the future the Radboud University. They consist of the Solaris-Panoptes global network of optical robotic telescopes and the satellite laser ranging station in Borowiec, Poland. These assets will contribute to the Polish and European Space Surveillance and Tracking (SST) program. The Solaris component is composed of four autonomous observatories in the Southern Hemisphere. Solaris nodes are located at the South African Astronomical Observatory (Solaris-1 and Solaris-2), Siding Spring Observatory, Australia (Solaris-3) and Complejo Astronomico El Leoncito, Argentina (Solaris-4). They are equipped with 0.5-m telescopes on ASA DDM-160 direct drive mounts, Andor iKon-L cameras and housed in 3.5-m Baader Planetarium (BP) clamshell domes. The Panoptes component is a network of telescopes operated by software from Sybilla Technologies. It currently consists of 4 telescopes at three locations, all on GM4000 mounts. One 0.36-m (Panoptes-COAST, STL- 1001E camera, 3.5 BP clamshell dome) and one 0.43-m (Panoptes-PIRATE, FLI 16803 camera, 4.5-m BP clamshell dome, with planned exchange to 0.63-m) telescope are located at the Teide Observatory (Tenerfie, Canary Islands), one 0.6-m (Panoptes-COG, SBIG STX 16803 camera, 4.5-m BP clamshell dome) telescope in Garching, Germany and one 0.5-m (Panoptes-MAM, FLI 16803 camera, 4.5-m BP slit dome) in Mammendorf, Germany. Panoptes-COAST and Panoptes-PIRATE are owned by The Open University (UK). Panoptes-COG is owned by the Max Planck Institute

  20. Satellite RNAs and Satellite Viruses.

    Science.gov (United States)

    Palukaitis, Peter

    2016-03-01

    Satellite RNAs and satellite viruses are extraviral components that can affect either the pathogenicity, the accumulation, or both of their associated viruses while themselves being dependent on the associated viruses as helper viruses for their infection. Most of these satellite RNAs are noncoding RNAs, and in many cases, have been shown to alter the interaction of their helper viruses with their hosts. In only a few cases have the functions of these satellite RNAs in such interactions been studied in detail. In particular, work on the satellite RNAs of Cucumber mosaic virus and Turnip crinkle virus have provided novel insights into RNAs functioning as noncoding RNAs. These effects are described and potential roles for satellite RNAs in the processes involved in symptom intensification or attenuation are discussed. In most cases, models describing these roles involve some aspect of RNA silencing or its suppression, either directly or indirectly involving the particular satellite RNA.

  1. Correction: Spectroscopic characteristics of the OSIRIS near-backscattering crystal analyser spectrometer on the ISIS pulsed neutron source.

    Science.gov (United States)

    Telling, Mark T F; Campbell, Stuart I; Engberg, Dennis; Martín Y Marero, David; Andersen, Ken H

    2016-03-21

    Correction for 'Spectroscopic characteristics of the OSIRIS near-backscattering crystal analyser spectrometer on the ISIS pulsed neutron source' by Mark T. F. Telling et al., Phys. Chem. Chem. Phys., 2005, 7, 1255-1261.

  2. Centriolar satellites

    DEFF Research Database (Denmark)

    Tollenaere, Maxim A X; Mailand, Niels; Bekker-Jensen, Simon

    2015-01-01

    Centriolar satellites are small, microscopically visible granules that cluster around centrosomes. These structures, which contain numerous proteins directly involved in centrosome maintenance, ciliogenesis, and neurogenesis, have traditionally been viewed as vehicles for protein trafficking...... highlight newly discovered regulatory mechanisms targeting centriolar satellites and their functional status, and we discuss how defects in centriolar satellite components are intimately linked to a wide spectrum of human diseases....

  3. Satellite theory

    Science.gov (United States)

    Kozai, Y.

    1981-04-01

    The dynamical characteristics of the natural satellite of Mars, Jupiter, Saturn, Uranus and Neptune are analyzed on the basis of the solar tidal perturbation factor and the oblateness factor of the primary planet for each satellite. For the inner satellites, for which the value of the solar tidal factor is much smaller than the planetary oblateness factor, it is shown that the eccentricity and inclination of satellite orbits are generally very small and almost constant; several pairs of inner satellites are also found to exhibit commensurable mean motions, or secular accelerations in mean longitude. In the case of the outer satellites, for which solar perturbations are dominant, secular perturbations and long-period perturbations may be derived by the solution of equations of motion reduced to one degree of freedom. The existence of a few satellites, termed intermediary satellites, for which the solar tidal perturbation is on the order of the planetary oblateness factor, is also observed, and the pole of the orbital plane of the satellite is noted to execute a complex motion around the pole of the planet or the orbital plane of the planet.

  4. Equivalent Joint Space-Time Multiuser Detection for Uplink ISI-Corrupted Multicarrier CDMA Systems with Arbitrary Antenna Arrays

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The multicarrier code division multiple access (MC-CDMA) systems without cyclic prefix (CP) hold a finespectral efficiency though they are unavoidably corrupted by the intersymbol interference (ISI) over the finite impulseresponse (FIR) channel. We call MC-CDMA systems without CP the ISI-corrupted MC-CDMA systems in some sense.Considering the fact that combining antenna arrays with so-called ISI-corrupted MC-CDMA systems is advantageous insuppressing cochannel interference in cellular communication systems, this paper investigates ISI-corrupted MC-CDMAsystems with base station antenna arrays. Joint space-time multiuser detection (MUD) schemes for DS-CDMA systemswith antenna arrays have drawn much attention recently. Based upon them, we can derive the equivalent joint spatial-temporal MUD scheme for ISI-corrupted MC-CDMA systems with antenna arrays. In order to achieve this goal, anequivalent space-time estimation method of uplink vector channel is first derived for the ISI-corrupted MC-CDMA systemwith the arbitrary antenna array over frequency-selective fading channels. Then, based on the estimated equivalent space-time channel, an equivalent joint space-time multiuser detector is constructed. Computer simulations illustrate that ouralgorithm is more robust against noise and can well mitigate multiple access interference (MAI) in multiuser scenarios.

  5. 东华大学ISI Web of Knowledge数据库使用评估%Using Evaluation of ISI Web of Knowledge Database in Donghua University

    Institute of Scientific and Technical Information of China (English)

    陈惠兰; 吴素坤; 董政娥

    2009-01-01

    随着学校对图书馆经费投入的不断增加,数字环境下图书馆的合理使用变得越来越重要,其表现在数字资源上要有较多的用户访问和下载.从成员馆对比、登录情况、检索情况和成本等角度统计分析了东华大学ISI Web of Knowledge数据库使用情况,并分析讨论了读者群和多校区使用情况等,为图书馆电子资源订购提供有效依据.

  6. ESPA Satellite Dispenser for ORBCOMM Generation 2

    OpenAIRE

    2013-01-01

    ORBCOMM’s machine-to-machine (M2M) solutions offer global asset monitoring and messaging services through a powerful Low Earth Orbit (LEO) satellite constellation. The original constellation deployment consisted of thirtyfive satellites launched in the late 1990s. ORBCOMM is launching the new ORBCOMM Generation 2 (OG2) satellites to upgrade and expand the constellation network. The OG2 satellites being manufactured by Sierra Nevada Corporation will have more data capacity with the potential f...

  7. An Analysis of Marine Corps Beyond Line of Sight Wideband Satellite Communications Requirements

    Science.gov (United States)

    2010-09-01

    Network (SWAN) ............................................40 9. Tropo /Satellite Support Radio (TSSR) ............................................42...Service Tactical Communications Program TROPO ...tropospheric scatter TSSR..................................................tropospheric scatter ( TROPO )-satellite support radio TSST

  8. Daftar Isi

    Directory of Open Access Journals (Sweden)

    Jurnal Informatika JIFO

    2013-04-01

    Full Text Available MODEL REKOMENDASI BERBASIS FUZZY UNTUK PEMILIHAN SEKOLAH LANJUTAN TINGKAT ATAS Shofwatul ‘Uyun, Yuni Madikhatun440 - 450APLIKASI MOBILE DOCTOR UNTUK MENINGKATKAN LAYANAN MEDISGatot Santoso, Subandi, Husni Musthofa451 - 457PERANCANGAN LAYANAN STREAMING MULTIMEDIA  PADA M-LEARNINGSamuel Kristiyana, Gatot Santoso458 - 464PENGEMBANGAN DAN PERANCANGAN TEMPAT TIDUR BAYI (BABY BOXYANG ERGONOMIS MENGGUNAKAN SOFTWARE AUTOCAD DENGA PENDEKATAN DATA ANTROPOMETRI Agung Kristanto, Sugeng Triyono465 - 477PEMBUATAN APLIKASI SISTEM COMPETENCY BASED DEVELOPMENT PURPOSE BERBASIS WEBEko Aribowo, Ali Tarmuji, Prasetyo Herlambang478 - 485PENERAPAN TEKNOLOGI RIA UNTUK MEMBANGUN APLIKASI WEB DENGAN PENGAKSESAN REALTIME (Studi Kasus : Pemesanan Handphone OnlineFiftin Noviyanto , Ahmad Ashari 486 - 498PROGRAM STU

  9. Daftar Isi

    Directory of Open Access Journals (Sweden)

    Jurnal Informatika JIFO

    2013-04-01

    Full Text Available   SISTEM PENDUKUNG KEPUTUSAN BERBASIS  AHP (ANALYTICAL HIERARCHY PROCESS  UNTUK PENENTUAN KESESUAIAN PENGGUNAAN LAHAN  (STUDI KASUS: KABUPATEN SEMARANG Sri Hartati, Adi Nugroho   630 - 641 RANCANG BANGUN APLIKASI PEMBELAJARAN AGAMA ISLAM UNTUK ANAK-ANAK BERBASIS MULTIMEDIA INTERAKTIF DAN WEB Idhawati Hestiningsih, Budi Suyanto, Ahmad Ilyas, Dimas Adi Nugroho 642 - 653 ANALISIS PERBANDINGAN METODE 2D MEDIAN FILTER DAN MULTI LEVEL MEDIAN FILTER PADA PROSES PERBAIKAN CITRA DIGITAL Murinto, Bachrudin Muchtar 654 - 662 PERSEPSI DOSEN TERHADAP URGENSI BERBAGI PENGETAHUAN (KNOWLEDGE SHARING DI PERGURUAN TINGGI Agus Mulyanto 663 - 676 PROTOTIPE ALAT PEMBERI INFORMASI JARAK ANTAR KENDARAAN Slamet Handoko, Idhawati Hestiningsih, Rian Prasetio, Wildan Arief Arrosyidi   677 - 686 SISTEM INFORMASI GEOGRAFIS UNTUK PEMETAAN DAN PENCARIAN RUMAH SAKIT DI KOTA YOGYAKARTA Ika Arfiani 687 - 699  

  10. Exploiting Satellite Remote-Sensing Data in Fine Particulate Matter Characterization for Serving the Environmental Public Health Tracking Network (EPHTN): The HELIX-Atlanta Experience and NPOESS Implications

    Science.gov (United States)

    Al-Hamdan, Mohammad Z.; Crosson, William L.; Limaye, Ashutosh S.; Rickman, Douglas L.; Quattrochi, Dale A.; Estes, Maurice G.; Qualters, Judith R.; Sinclair, Amber H.; Tolsma, Dennis D.; Adeniyi, Kafayat A.

    2008-01-01

    As part of the U.S. National Environmental Public Health Tracking Network (EPHTN), the National Center for Environmental Health (NCEH) at the U.S. Centers for Disease Control and Prevention (CDC) led a project in collaboration with the National Aeronautics and Space Administration (NASA) Marshall Space Flight Center (MSFC) called Health and Environment Linked for Information Exchange (HELIX-Atlanta). Under HELIX-Atlanta, pilot projects were conducted to develop methods to better characterize exposure; link health and environmental datasets; and analyze spatial/temporal relationships. This paper describes and demonstrates different techniques for surfacing daily environmental hazards data of particulate matter with aerodynamic diameter less than or equal to 2.5 micrometers (PM(sub 2.5) for the purpose of integrating respiratory health and environmental data for the CDC's pilot study of HELIX-Atlanta. It describes a methodology for estimating ground-level continuous PM(sub 2.5) concentrations using spatial surfacing techniques and leveraging NASA Moderate Resolution Imaging Spectrometer (MODIS) data to complement the U.S. Environmental Protection Agency (EPA) ground observation data. The study used measurements of ambient PM(sub 2.5) from the EPA database for the year 2003 as well as PM(sub 2.5) estimates derived from NASA's MODIS data. Hazard data have been processed to derive the surrogate exposure PM(sub 2.5) estimates. The paper has shown that merging MODIS remote sensing data with surface observations of PM(sub 2.5), may provide a more complete daily representation of PM(sub 2.5), than either data set alone would allow, and can reduce the errors in the PM(sub 2.5) estimated surfaces. Future work in this area should focus on combining MODIS column measurements with profile information provided by satellites like the National Polar-orbiting Operational Environmental Satellite System (NPOESS). The Visible Infrared Imager/Radiometer Suite (VIIRS) and the Aerosol

  11. A working environment for digital planetary data processing and mapping using ISIS and GRASS GIS

    Science.gov (United States)

    Frigeri, Alessandro; Hare, Trent; Neteler, Markus; Coradini, Angioletta; Federico, Costanzo; Orosei, Roberto

    2011-09-01

    Since the beginning of planetary exploration, mapping has been fundamental to summarize observations returned by scientific missions. Sensor-based mapping has been used to highlight specific features from the planetary surfaces by means of processing. Interpretative mapping makes use of instrumental observations to produce thematic maps that summarize observations of actual data into a specific theme. Geologic maps, for example, are thematic interpretative maps that focus on the representation of materials and processes and their relative timing. The advancements in technology of the last 30 years have allowed us to develop specialized systems where the mapping process can be made entirely in the digital domain. The spread of networked computers on a global scale allowed the rapid propagation of software and digital data such that every researcher can now access digital mapping facilities on his desktop. The efforts to maintain planetary missions data accessible to the scientific community have led to the creation of standardized digital archives that facilitate the access to different datasets by software capable of processing these data from the raw level to the map projected one. Geographic Information Systems (GIS) have been developed to optimize the storage, the analysis, and the retrieval of spatially referenced Earth based environmental geodata; since the last decade these computer programs have become popular among the planetary science community, and recent mission data start to be distributed in formats compatible with these systems. Among all the systems developed for the analysis of planetary and spatially referenced data, we have created a working environment combining two software suites that have similar characteristics in their modular design, their development history, their policy of distribution and their support system. The first, the Integrated Software for Imagers and Spectrometers (ISIS) developed by the United States Geological Survey

  12. A working environment for digital planetary data processing and mapping using ISIS and GRASS GIS

    Science.gov (United States)

    Frigeri, A.; Hare, T.; Neteler, M.; Coradini, A.; Federico, C.; Orosei, R.

    2011-01-01

    Since the beginning of planetary exploration, mapping has been fundamental to summarize observations returned by scientific missions. Sensor-based mapping has been used to highlight specific features from the planetary surfaces by means of processing. Interpretative mapping makes use of instrumental observations to produce thematic maps that summarize observations of actual data into a specific theme. Geologic maps, for example, are thematic interpretative maps that focus on the representation of materials and processes and their relative timing. The advancements in technology of the last 30 years have allowed us to develop specialized systems where the mapping process can be made entirely in the digital domain. The spread of networked computers on a global scale allowed the rapid propagation of software and digital data such that every researcher can now access digital mapping facilities on his desktop. The efforts to maintain planetary missions data accessible to the scientific community have led to the creation of standardized digital archives that facilitate the access to different datasets by software capable of processing these data from the raw level to the map projected one. Geographic Information Systems (GIS) have been developed to optimize the storage, the analysis, and the retrieval of spatially referenced Earth based environmental geodata; since the last decade these computer programs have become popular among the planetary science community, and recent mission data start to be distributed in formats compatible with these systems. Among all the systems developed for the analysis of planetary and spatially referenced data, we have created a working environment combining two software suites that have similar characteristics in their modular design, their development history, their policy of distribution and their support system. The first, the Integrated Software for Imagers and Spectrometers (ISIS) developed by the United States Geological Survey

  13. Aerosol height retrieval from satellite visible measurements: application to OMI 477 nm O2-O2 spectral band, based on Neural Networks

    Science.gov (United States)

    Chimot, Julien; Veefkind, Pepijn; Vlemmix, Tim; Levelt, Pieternel

    2017-04-01

    The ability to monitor air quality and climate from UltraViolet-Visible (UV-Vis) satellite spectral measurements relies on accurate trace gas (e.g. NO2, SO2, HCHO, O3) columns combined with aerosol properties and vertical distribution. In the absence of clouds, the most important error source on the observations of trace gases in the troposphere are aerosols, since their scattering and absorbing properties modify the average light path followed by the detected photons. Large impacts due to their vertical distribution uncertainties remain when retrieving vertical column densities of trace gases from UV-Vis air quality space-borne sensors [Krotkov et al., 2008; Boersma et al., 2011; Barkley et al., 2012; Hewson et al., 2015; Castellanos et al., 2015; Chimot et al., 2016a]. Aerosols and trace gases share, over urban and industrialized areas, similar anthropogenic sources, and their concentrations, as shown by the satellite observations, often present significant correlations [Veefkind et al., 2011]. We have recently developed a Multilayer Perceptron Neural Network (NN) algorithm to retrieve Aerosol Layer Height (ALH) from the OMI 477 nm O2-O2 absorption band [Chimot et al., 2016b]. This algorithm represents aerosols in the troposphere as a single scattering layer defined by its mean altitude and homogeneous optical properties. This algorithm enables the link between the OMI O2-O2 slant column density derived from the 477 nm spectral measurements and the aerosol layer altitude. A prior information about the Aerosol Optical Thickness (AOT) is needed to distinguish the effects due to the amount of fine particles and their altitude. Therefore, the ALH retrieval strongly benefits from a synergy between OMI 477 nm O2-O2 spectral measurements and MODIS AOT product. Aerosol layer heights are currently retrieved with an uncertainty in the range of 260-800 m for scenes with AOT larger than 1. Improvement of these retrievals can be expected by improving assumptions on the

  14. Assessment of small-scale variability of rainfall and multi-satellite precipitation estimates using measurements from a dense rain gauge network in Southeast India

    Science.gov (United States)

    Sunilkumar, K.; Narayana Rao, T.; Satheeshkumar, S.

    2016-05-01

    This paper describes the establishment of a dense rain gauge network and small-scale variability in rain events (both in space and time) over a complex hilly terrain in Southeast India. Three years of high-resolution gauge measurements are used to validate 3-hourly rainfall and sub-daily variations of four widely used multi-satellite precipitation estimates (MPEs). The network, established as part of the Megha-Tropiques validation program, consists of 36 rain gauges arranged in a near-square grid area of 50 km × 50 km with an intergauge distance of 6-12 km. Morphological features of rainfall in two principal rainy seasons (southwest monsoon, SWM, and northeast monsoon, NEM) show marked differences. The NEM rainfall exhibits significant spatial variability and most of the rainfall is associated with large-scale/long-lived systems (during wet spells), whereas the contribution from small-scale/short-lived systems is considerable during the SWM. Rain events with longer duration and copious rainfall are seen mostly in the western quadrants (a quadrant is 1/4 of the study region) in the SWM and northern quadrants in the NEM, indicating complex spatial variability within the study region. The diurnal cycle also exhibits large spatial and seasonal variability with larger diurnal amplitudes at all the gauge locations (except for 1) during the SWM and smaller and insignificant diurnal amplitudes at many gauge locations during the NEM. On average, the diurnal amplitudes are a factor of 2 larger in the SWM than in the NEM. The 24 h harmonic explains about 70 % of total variance in the SWM and only ˜ 30 % in the NEM. During the SWM, the rainfall peak is observed between 20:00 and 02:00 IST (Indian Standard Time) and is attributed to the propagating systems from the west coast during active monsoon spells. Correlograms with different temporal integrations of rainfall data (1, 3, 12, 24 h) show an increase in the spatial correlation with temporal integration, but the

  15. Longitudinal analysis of meta-analysis literatures in the database of ISI Web of Science.

    Science.gov (United States)

    Zhu, Changtai; Jiang, Ting; Cao, Hao; Sun, Wenguang; Chen, Zhong; Liu, Jinming

    2015-01-01

    The meta-analysis is regarded as an important evidence for making scientific decision. The database of ISI Web of Science collected a great number of high quality literatures including meta-analysis literatures. However, it is significant to understand the general characteristics of meta-analysis literatures to outline the perspective of meta-analysis. In this present study, we summarized and clarified some features on these literatures in the database of ISI Web of Science. We retrieved the meta-analysis literatures in the database of ISI Web of Science including SCI-E, SSCI, A&HCI, CPCI-S, CPCI-SSH, CCR-E, and IC. The annual growth rate, literature category, language, funding, index citation, agencies and countries/territories of the meta-analysis literatures were analyzed, respectively. A total of 95,719 records, which account for 0.38% (99% CI: 0.38%-0.39%) of all literatures, were found in the database. From 1997 to 2012, the annual growth rate of meta-analysis literatures was 18.18%. The literatures involved in many categories, languages, fundings, citations, publication agencies, and countries/territories. Interestingly, the index citation frequencies of the meta-analysis were significantly higher than that of other type literatures such as multi-centre study, randomize controlled trial, cohort study, case control study, and cases report (P<0.0001). The increasing numbers, intensively global influence and high citations revealed that the meta-analysis has been becoming more and more prominent in recent years. In future, in order to promote the validity of meta-analysis, the CONSORT and PRISMA standard should be continuously popularized in the field of evidence-based medicine.

  16. Probabilistic Decision Making with Spikes: From ISI Distributions to Behaviour via Information Gain.

    Directory of Open Access Journals (Sweden)

    Javier A Caballero

    Full Text Available Computational theories of decision making in the brain usually assume that sensory 'evidence' is accumulated supporting a number of hypotheses, and that the first accumulator to reach threshold triggers a decision in favour of its associated hypothesis. However, the evidence is often assumed to occur as a continuous process whose origins are somewhat abstract, with no direct link to the neural signals - action potentials or 'spikes' - that must ultimately form the substrate for decision making in the brain. Here we introduce a new variant of the well-known multi-hypothesis sequential probability ratio test (MSPRT for decision making whose evidence observations consist of the basic unit of neural signalling - the inter-spike interval (ISI - and which is based on a new form of the likelihood function. We dub this mechanism s-MSPRT and show its precise form for a range of realistic ISI distributions with positive support. In this way we show that, at the level of spikes, the refractory period may actually facilitate shorter decision times, and that the mechanism is robust against poor choice of the hypothesized data distribution. We show that s-MSPRT performance is related to the Kullback-Leibler divergence (KLD or information gain between ISI distributions, through which we are able to link neural signalling to psychophysical observation at the behavioural level. Thus, we find the mean information needed for a decision is constant, thereby offering an account of Hick's law (relating decision time to the number of choices. Further, the mean decision time of s-MSPRT shows a power law dependence on the KLD offering an account of Piéron's law (relating reaction time to stimulus intensity. These results show the foundations for a research programme in which spike train analysis can be made the basis for predictions about behavior in multi-alternative choice tasks.

  17. River flow forecasting with Artificial Neural Networks using satellite observed precipitation pre-processed with flow length and travel time information: case study of the Ganges river basin

    Directory of Open Access Journals (Sweden)

    M. K. Akhtar

    2009-04-01

    Full Text Available This paper explores the use of flow length and travel time as a pre-processing step for incorporating spatial precipitation information into Artificial Neural Network (ANN models used for river flow forecasting. Spatially distributed precipitation is commonly required when modelling large basins, and it is usually incorporated in distributed physically-based hydrological modelling approaches. However, these modelling approaches are recognised to be quite complex and expensive, especially due to the data collection of multiple inputs and parameters, which vary in space and time. On the other hand, ANN models for flow forecasting are frequently developed only with precipitation and discharge as inputs, usually without taking into consideration the spatial variability of precipitation. Full inclusion of spatially distributed inputs into ANN models still leads to a complex computational process that may not give acceptable results. Therefore, here we present an analysis of the flow length and travel time as a basis for pre-processing remotely sensed (satellite rainfall data. This pre-processed rainfall is used together with local stream flow measurements of previous days as input to ANN models. The case study for this modelling approach is the Ganges river basin. A comparative analysis of multiple ANN models with different hydrological pre-processing is presented. The ANN showed its ability to forecast discharges 3-days ahead with an acceptable accuracy. Within this forecast horizon, the influence of the pre-processed rainfall is marginal, because of dominant influence of strongly auto-correlated discharge inputs. For forecast horizons of 7 to 10 days, the influence of the pre-processed rainfall is noticeable, although the overall model performance deteriorates. The incorporation of remote sensing data of spatially distributed precipitation information as pre-processing step showed to be a promising alternative for the setting-up of ANN models for

  18. 7-12 -vuotiaiden lasten ylipainon ennaltaehkäisy - Kirjallisuuskatsaus

    OpenAIRE

    Sänkiaho, Laura; Santtila, Jonna

    2013-01-01

    Opinnäytetyö käsittelee lasten ylipainoisuutta, joka on nykyään yleinen terveysongelma. Lapsuusajan ylipainon haitalliset terveysvaikutukset säilyvät aikuisuuteen, joten ylipainon ennaltaehkäisy jo lapsuudessa on tärkeää. Opinnäytetyön tarkoituksena oli selvittää vastaukset seuraaviin kysymyksiin: mitkä tekijät johtavat 7-12 –vuotiaiden lasten ylipainon kehittymiseen ja millä keinoilla tämän ikäisten lasten ylipainoa voidaan ennaltaehkäistä terveydenhuollossa. Tavoitteena oli saada kerätyksi ...

  19. Una yihad visual: imágenes hiperreales del terror en las producciones audiovisuales de ISIS

    OpenAIRE

    Lucas Reydó

    2015-01-01

    Las recientes producciones audiovisuales del grupo yihadista conocido internacionalmente como Estado Islámico (ISIS, ISIL, o bien EI), presentan ciertas características en sus montajes que no encuentran parangón con aquellas de anteriores grupos terroristas a lo largo de la historia. El presente ensayo se propone indagar en las formas contemporáneas del terrorismo a partir del análisis semiológico de los videos difundidos por el EI. Para ello, se recurre a las perspectivas teórico-e...

  20. Kiusaamisen ennaltaehkäisy päiväkoti Kuperkeikassa

    OpenAIRE

    Mäkelä, Jenna

    2017-01-01

    Opinnäytetyön tarkoituksena oli selvittää lasten näkemyksiä kiusaamisesta sekä edistää kiusaamisen ennaltaehkäisyä varhaiskasvatuksessa. Opinnäytetyö tehtiin päiväkoti Kuperkeikalle Nakkilaan. Teoriaosuudessa käsiteltiin pienten lasten kiusaamista, leikkiä, sosiaalisia taitoja, tunteiden käsittelyä ja päiväkodin ja kodin välistä yhteistyötä. Lasten näkemyksiä kiusaamisesta selvitettiin toiminnallisella tuokiolla. Tuokion alussa luettiin satu, jonka pohjustamana keskusteltiin kiusaami...

  1. 75 FR 80425 - Satellite Television Extension and Localism Act of 2010 and Satellite Home Viewer Extension and...

    Science.gov (United States)

    2010-12-22

    ... COMMISSION 47 CFR Part 73 Satellite Television Extension and Localism Act of 2010 and Satellite Home Viewer... requirements and provisions of the Satellite Television Extension and Localism Act of 2010 (STELA). This model... satellite television service is eligible for delivery of distant network signals from that service....

  2. Backbone-access integration space information network system design based on MEO satellite%面向空间信息网络的骨干接入一体化MEO卫星系统设计

    Institute of Scientific and Technical Information of China (English)

    陈荷; 乔洋; 陈晶; 赵艳彬

    2016-01-01

    以我国空间信息的应用需求为牵引,设计了一种系统管理简单、成本可控的空间光网络系统。该系统利用MEO卫星组成环形骨干光网络,兼顾微波接入功能,实现骨干接入一体化、激光微波混合化的空间信息网络系统,并对系统覆盖能力进行了仿真,同时结合GEO中继系统和LEO卫星系统的特点,提出分步建设思想,最终实现全球信息传输和应用的空间信息网络系统。%In demand for the application of China’ s space information, a simple-managing and controllable-cost space optical network was designed. The established circle backbone network based on MEO satellites was equipped with microwave access ability to realize the backbone-access integrated and optical-microwave hybrid space network system. Coverage capacity was also simulated. The implementation scheme by step which was proposed based on the combination of the characteristics of the GEO relay system and the LEO satellite as well will contribute to the space network system for global information transmission and application.

  3. Satellite Communications

    CERN Document Server

    Pelton, Joseph N

    2012-01-01

    The field of satellite communications represents the world's largest space industry. Those who are interested in space need to understand the fundamentals of satellite communications, its technology, operation, business, economic, and regulatory aspects. This book explains all this along with key insights into the field's future growth trends and current strategic challenges. Fundamentals of Satellite Communications is a concise book that gives all of the key facts and figures as well as a strategic view of where this dynamic industry is going. Author Joseph N. Pelton, PhD, former Dean of the International Space University and former Director of Strategic Policy at Intelstat, presents a r

  4. LEO卫星网络中一种简洁的星上分布式路由协议%A Light Weight On-Board Distributed Routing Protocol for LEO Satellite Networks

    Institute of Scientific and Technical Information of China (English)

    白建军; 卢锡城; 彭伟

    2005-01-01

    在具有星际链路的低地球轨道(LEO)卫星网络中,高度动态的网络拓扑和受限的星上资源为其路由协议设计带来很大的挑战.提出了一种简洁的星上分布式路由协议ODRP来应对这种挑战.在ODRP协议中,单层LEO星座被作为双层星座处理.根据星际链路动态特性和流量分布情况,各轨道面内位于一定位置的卫星节点被选作为轨道面发言人,从而实现简洁的分布式分层路由.实验结果表明,ODRP能够适应网络拓扑的动态变化,保证路由最优.尤其是在高负载情况下,能够有效降低分组丢失率.通过复杂性分析得知,与其他星上路由机制相比,ODRP具有较低的通信开销、计算开销和存储开销.%In LEO satellite networks with inter-satellite links, the highly dynamic topology and the limited on-board resources pose special challenges to routing protocol design. In this paper, a light weight on-board distributed routing protocol is proposed to cope with these challenges. For ODRP, the single layer LEO satellite constellation is considered as double-layer constellation. A satellite at special geographical position is selected as the plane speaker according to the dynamic characteristics of inter-satellite links and the distribution of traffic load carried by the network, consequently the idea of distributed hierarchical routing is realized. Experimental results show that ODRP has the adaptive abilities to deal with the dynamic topology of LEO satellite networks and guarantees the path's optimality, and especially can decrease the packet loss probability efficiently in case of high traffic load. Furthermore, results from the implementation complexity analysis demonstrate that the proposed protocol has lower onboard computational, storage and signaling requirements than other on-board routing schemes.

  5. Commercial satellite broadcasting for Europe

    Science.gov (United States)

    Forrest, J. R.

    1988-12-01

    A review is presented of the current television broadcasting situation in European countries, which involves a varied mix of terrestrial VHF or UHF systems and cable networks. A small market has emerged in Europe for receivers using the low-power telecommunications satellite transmission between the program providers and cable network companies. This is expected to change with the launch of medium-power pan-European telecommunication satellites (e.g. ASTRA, EUTELSAT II), which are now directly addressing the market of home reception. DBS (direct broadcast satellite) in the UK, using the D-MAC transmission standard, will offer three additional television channels, data broadcasting services, and a planned evolution to compatible forms of wide-screen, high-definition television. Comments are given on receiver and conditional access system standardization. Some views are expressed on satellite broadcasting as part of an overall broadcasting framework for the future.

  6. Satellite Communications for ATM

    Science.gov (United States)

    Shamma, Mohammed A.

    2003-01-01

    This presentation is an overview on Satellite Communication for the Aeronautical Telecommunication Management (ATM) research. Satellite Communications are being considered by the FAA and NASA as a possible alternative to the present and future ground systems supporting Air Traffic Communications. The international Civil Aviation Organization (ICAO) have in place Standards and Recommended Practices (SARPS) for the Aeronautical Mobile Satellite Services (AMSS) which is mainly derived from the pre-existing Inmarsat service that has been in service since the 1980s. The Working Group A of the Aeronautical Mobile Communication Panel of ICAO has also been investigating SARPS for what is called the Next Generation Satellite Service (NGSS) which conforms less to the Inmarsat based architecture and explores wider options in terms of satellite architectures. Several designs are being proposed by Firms such as Boeing, ESA, NASA that are geared toward full or secondary usage of satellite communications for ATM. Satellite communications for ATM can serve several purposes ranging from primary usage where ground services would play a minimal backup role, to an integrated solution where it will be used to cover services, or areas that are less likely to be supported by the proposed and existing ground infrastructure. Such Integrated roles can include usage of satellite communications for oceanic and remote land areas for example. It also can include relieving the capacity of the ground network by providing broadcast based services of Traffic Information Services messages (TIS-B), or Flight Information Services (FIS-B) which can take a significant portion of the ground system capacity. Additionally, satellite communication can play a backup role to support any needs for ground replacement, or additional needed capacity even after the new digital systems are in place. The additional bandwidth that can be provided via satellite communications can also open the door for many new

  7. TELECOM 1 multiservices network

    Science.gov (United States)

    Lombard, D.; Ramat, P.; Rancy, F.

    The main objectives of the TELECOM 1 French domestic satellite project are to set up a business communication network which is to carry a wide range of digital services including data, voice, and pictures between a number of small earth stations located on the subscribers' premises. The parallel development of terrestrial specialized services networks has enabled the fitting of the TELECOM 1 network with high interworking capabilities with these networks. It has also allowed TELECOM 1 to be designed as the basis of the Future Integrated Services Digital Network. The TELECOM 1 network consists of the terrestrial network, the satellite network, and the maintenance network. Various elements which include the terrestrial network; the satellite network, and its modulation, TDMA frame and terminals; the System Management Center; the signalling system; and the demand assignment operation which are involved in the operation of the multiservices network are presented. The TELECOM 1 network evolution until 1990 through the rapid development of the ISDN is discussed.

  8. Analysis on Connectivity of Inter-Orbit-Links in a MEO/LEO Double-Layer Satellite Network%MEO/LEO双层卫星网络中层间链路的连接度分析

    Institute of Scientific and Technical Information of China (English)

    王振永; 李集林; 郭庆; 顾学迈

    2006-01-01

    作为未来卫星移动通信系统的一个重要的研究方向,提出了一种由MEO卫星和LEO卫星共同组成的双层卫星网络(Double-Layer Satellite Network,DLSN),以更好为用户提供多媒体服务.作为多层卫星网络的一个重要的研究内容,连接不同高度上卫星的层间链路(Inter-Orbit-Links,IOLs)的特性对于整个DLSN网络的性能会有很大的影响.根据所设计的多层卫星网络的星座参数,通过对层间链路几何特性的研究,分析了多层卫星网络中MEO卫星与LEO卫星的连接度性能.采用计算机仿真的方法,给出了层间链路连接度的特性.结果表明,为了提高网络性能,在多层卫星网络中应按照一定参数有选择的建立层间链路,而不是简单的采用视距可见原则建立层间链路.%As an important scheme of future global mobile satellite communication systems to provide multimedia service, a Double-Layer Satellite Network (DLSN) with MEO satellites and LEO satellites is proposed.The Inter-Orbit-Links (IOLs) between layers is an essential factor, which affects the performances of the DLSN systems. Considering certain constellation parameters, the geometric characteristics of IOLs are described and the connectivity of MEO satellites and LEO satellites in the DLSN is analyzed. By computer simulation, the results show that IOLs should be selectively established according to certain parameters rather than the simple in-sight principle.

  9. Satellite Geomagnetism

    DEFF Research Database (Denmark)

    Olsen, Nils; Stolle, Claudia

    2012-01-01

    Observations of Earth’s magnetic field from space began more than 50 years ago. A continuous monitoring of the field using low Earth orbit (LEO) satellites, however, started only in 1999, and three satellites have taken highprecision measurements of the geomagnetic field during the past decade...... ability to characterize and understand the many sources that contribute to Earth’s magnetic field. In this review, we summarize investigations of Earth’s interior and environment that have been possible through the analysis of high-precision magnetic field observations taken by LEO satellites........ The unprecedented time-space coverage of their data opened revolutionary new possibilities for monitoring, understanding, and exploring Earth’s magnetic field. In the near future, the three-satellite constellation Swarm will ensure continuity of such measurement and provide enhanced possibilities to improve our...

  10. Satellite (Natural)

    Science.gov (United States)

    Murdin, P.

    2000-11-01

    In its most general sense, any celestial object in orbit around a similar larger object. Thus, for example, the Magellanic Clouds are satellite galaxies of our own Milky Way galaxy. Without qualification, the term is used to mean a body in orbit around a planet; an alternative term is moon. The term natural satellite distinguishes these bodies from artificial satellites—spacecraft placed in orbi...

  11. Seven decades of history of science: I. Bernard Cohen (1914-2003), second editor of Isis.

    Science.gov (United States)

    Dauben, Joseph W; Gleason, Mary Louise; Smith, George E

    2009-03-01

    I. Bernard Cohen (1914-2003), the first American to receive a Ph.D. in history of science, was a Harvard undergraduate ('37) and then a Ph.D. student and protégé of George Sarton, founder of Isis and the History of Science Society. He went on to succeed Sarton as editor of Isis (1952-1958) and, later, president of the Society (1961-1962); he was also a president of the International Union of the History and Philosophy of Science. Cohen was an internationally recognized Newton scholar; his interests were encyclopedic, ranging from science and public policy to the history of computers, with several decades as a special consultant for history of computing with IBM. Among his hundreds of publications were such major books as Franklin and Newton (1956), The Birth of a New Physics (1959; rpt., 1985), The Newtonian Revolution (1980), Revolution in Science (1985), Science and the Founding Fathers (1995), Howard Aiken: Portrait of a Computer Pioneer (1999), and his last book, The Triumph of Numbers (2005), not to mention two jointly authored contributions, the variorum edition and new English translation of Newton's Principia, which will surely still be read a century from now.

  12. Investigations with Gaseous Electron Multipliers for use on the ISIS spallation neutron source

    Science.gov (United States)

    Duxbury, D.; Rhodes, N.; Schooneveld, E.; Spill, E.

    2012-01-01

    Several investigations have been undertaken to ascertain the suitability of gaseous electron multipliers (GEMs) for use as a neutron detector on the ISIS spallation neutron source. Our initial investigations focused purely on whether these devices could be operated at the elevated pressure of 3He and CF4 necessary for 1mm position resolution (2.6 bars of CF4). In fact we were able to operate the GEMs at suitable gains with 3.5 bars of CF4. However encouraging these results were, we found that the GEMs charged up over time, which we postulated was due to the kapton substrate. A similar problem was seen at the early stages of the development of the microstrip gas chamber (MSGC), a solution of which was to use the semiconducting glass Schott S8900 as the substrate. Therefore we focused our attention to the manufacture of a GEM structure on an S8900 substrate. Our first devices were manufactured from 1mm thick glass and exhibit gains in excess of 1 × 104 for a single GEM stage in an argon isobutane gas mixture, when illuminated with 55Fe x-rays. A small amount of charging under irradiation has been observed in a flowing gas mixture, but the GEMs quickly stabilise and track atmospheric conditions. Further measurements in a 3He:CF4 atmosphere will show how suited these devices are to the needs of ISIS.

  13. A critical analysis of ‘face’-managing factors in isiZulu idioms

    Directory of Open Access Journals (Sweden)

    M.R. Masubelele

    2015-03-01

    Full Text Available People have an inherent need to communicate. They communicate out of need as well as for leisure. Human speech abounds with unpleasant and undesirable statements that could embarrass and even humiliate those spoken to or oneself. Brown and Levinson assert that unpleasant and undesirable statements have the potential to threaten the ‘face’ or self-esteem of the other person or persons. They define ‘face’ as the public self-image that every member of society wants to claim for themself. Simply put, ‘facework’ refers to ways people cooperatively attempt to promote both the other’s and their own sense of self-esteem in a conversation. As linguistic speech forms, idioms perform a variety of functions in a language. Not only do they make speech more colourful, but they also perform a communicative function in that they tend to soften the embarrassment and humiliation that often accompanies unpleasant and undesirable statements in speech. IsiZulu idioms will be examined in this article to establish to what extent they could contribute to managing ‘face’ issues. Examples of idioms will be drawn from C.L.S. Nyembezi and O.E.H. Nxumalo’s work Inqolobane Yesizwe. The facework theory as espoused by Brown and Levinson will underpin this discussion on isiZulu idioms.

  14. Feminismos en clave latinoamericana: un recorrido sobre Fem, Isis y Fempress

    Directory of Open Access Journals (Sweden)

    Karin Grammático

    2011-09-01

    Full Text Available En este artículo presentamos un recorrido histórico de tres de los más destacados proyectos de comunicación que el feminismo contemporáneo latinoamericano llevó adelante en el último cuarto del siglo XX: la revista mexicana Fem, iniciativa pionera que se esforzó por combinar la producción teórica y creación feministas con las demandas políticas del movimiento de mujeres, y los emprendimientos comunicacionales que llevaron adelante Isis Internacional y Fempress.In this paper we present a historical overview of the three most outstanding projects of communication that the contemporary Latin American feminism carried on in the last quarter of the last century: the Mexican magazine Fem, a pioneering initiative which attempted to combine the theoretical and creative productions with the political demands of women's movement, and the communication enterprises carried out by Fempress and Isis International.

  15. Operation and Thermal Modeling of the ISIS H– Source from 50 to 2 Hz Repetition Rates

    CERN Document Server

    Pereira, H; Lettry, J

    2013-01-01

    CERN’s Linac4 accelerator H− ion source, currently under construction, will operate at a 2 Hz repetition rate, with pulse length of 0.5 ms and a beam current of 80 mA. Its reliability must exceed 99 % with a mandatory 3 month uninterrupted operation period. A Penning ion source is successfully operated at ISIS; at 50 Hz repetition rate it reliably provides 55 mA H− pulses of 0.25 ms duration over 1 month. The discharge plasma ignition is very sensitive to the temperatures of the discharge region, especially of its cathode. The investigation by modeling and measurement of operation parameters suitable for arc ignition and H− production at 2 Hz is of paramount importance and must be understood prior to the implementation of discharge ion sources in the Linac4 accelerator. In its original configuration, the ISIS H− source delivers beam only if the repetition rate is above 12.5 Hz, this paper describes the implementation of a temperature control of the discharge region aiming at lower repetition rate op...

  16. ISI Web of Knowledge(R)平台上信息资源的收集

    Institute of Scientific and Technical Information of China (English)

    刘煜; 郭利

    2003-01-01

    本文介绍了ISI编辑发展部关于收录文献源的筛选程序,特别详细地描述了有关ISI Web of Science(包括SCIE、SSCI、A&HCI)的选刊过程.指出ISI的选择程序包括四个主要方面,即考查期刊出版标准、编辑内容、国际多样性和引文分析,并由此给出了影响因子的定义.此外,还给出了为ISI Proceedings(包括ISTP/ISSHP)筛选会议录和为Current WebContents筛选网站内容的程序.文中还介绍了Web of Knowledge平台收录中文期刊和中文网站的一般情况.

  17. Correlation between size and external temperature of the ISIS 130 tumour after treatment with cytostatic agents.

    Science.gov (United States)

    Nickers, P; Oosters, L; Brasseur, F; Deckers-Passau, L; Maisin, H; Deckers, C

    1986-07-01

    The reduction in size of the experimental ISIS 130 tumour has been investigated in LOU rats under the influence of increasing doses of cytostatic agents belonging to different classes. External temperatures of tumours as well as rectal temperatures have been measured at the same time, twice daily, during the whole experiment. The greater the decrease in the tumour size after drug administration, the larger was the decrease in external temperature of tumour. The rectal temperatures remained fairly stable, thus differences between the tumour and rectal temperatures increased. A possible correlation between the reduction of tumour size and the decrease of external temperature of tumour has been traced for every cytostatic agent, and the same linear relationship has been found to link these two parameters. The decrease in external temperature of tumour may, moreover, predict the decrease in tumour size within a term of 1-2 days. Measurement of the magnitude of the transient tumour hypothermia of ISIS 130, following chemotherapy, would represent a new method for measuring the efficiency and duration of action of cytostatic agents.

  18. ISDN - The case for satellites

    Science.gov (United States)

    Pelton, Joseph N.; McDougal, Patrick J.

    1987-05-01

    The Integrated Services Digital Network (ISDN) holds much promise for both suppliers and users of telecommunications in the near future. This article examines the role of satellites in this new ISDN environment and emphasizes several advantages of satellites in the ongoing evolution to an all-digital world. In specific, the role of Intelsat, the global satellite system, is discussed with emphasis on Intelsat's digital services which today can offer all the characteristics and standards of ISDN in a flexible, cost-efficient manner.

  19. Select Correctly the Contributed Journals in SCIE Microbiological Research Fields with ISI Web of Knowledge%应用ISI Web of Knowledge正确选择SCIE微生物研究领域投稿期刊

    Institute of Scientific and Technical Information of China (English)

    孙湛芃

    2010-01-01

    在介绍ISI Web of Knowledge,ISI Web of Science,Journal Citation Repots,Science Citation Index Expanded等情况的基础上,较为详细地分析了如何获取SCIE微生物研究领域来源期刊信息,如何利用SCIE和JCR检索与分析系统来选择投稿期刊以及如何快捷投稿的方法.

  20. Neural network-based estimates of Southern Ocean net community production from in-situ O2 / Ar and satellite observation: a methodological study

    Directory of Open Access Journals (Sweden)

    C.-H. Chang

    2013-10-01

    Full Text Available Southern Ocean organic carbon export plays an important role in the global carbon cycle, yet its basin-scale climatology and variability are uncertain due to limited coverage of in situ observations. In this study, a neural network approach based on the self-organizing map (SOM is adopted to construct weekly gridded (1° × 1° maps of organic carbon export for the Southern Ocean from 1998 to 2009. The SOM is trained with in situ measurements of O2 / Ar-derived net community production (NCP that are tightly linked to the carbon export in the mixed layer on timescales of 1–2 weeks, and six potential NCP predictors: photosynthetically available radiation (PAR, particulate organic carbon (POC, chlorophyll (Chl, sea surface temperature (SST, sea surface height (SSH, and mixed layer depth (MLD. This non-parametric approach is based entirely on the observed statistical relationships between NCP and the predictors, and therefore is strongly constrained by observations. A thorough cross-validation yields three retained NCP predictors, Chl, PAR, and MLD. Our constructed NCP is further validated by good agreement with previously published independent in situ derived NCP of weekly or longer temporal resolution through real-time and climatological comparisons at various sampling sites. The resulting November–March NCP climatology reveals a pronounced zonal band of high NCP roughly following the subtropical front in the Atlantic, Indian and western Pacific sectors, and turns southeastward shortly after the dateline. Other regions of elevated NCP include the upwelling zones off Chile and Namibia, Patagonian Shelf, Antarctic coast, and areas surrounding the Islands of Kerguelen, South Georgia, and Crozet. This basin-scale NCP climatology closely resembles that of the satellite POC field and observed air-sea CO2 flux. The long-term mean area-integrated NCP south of 50° S from our dataset, 14 mmol C m–2 d–1, falls within the range of 8.3–24 mmol C m

  1. Characterising Vegetation Structural and Functional Differences Across Australian Ecosystems From a Network of Terrestrial Laser Scanning Survey Sites and Airborne and Satellite Image Archives

    Science.gov (United States)

    Phinn, S. R.; Armston, J.; Scarth, P.; Johansen, K.; Schaefer, M.; Suarez, L.; Soto-Berelov, M.; Muir, J.; Woodgate, W.; Jones, S.; Held, A. A.

    2015-12-01

    Vegetation structural information is critical for environmental monitoring, management and compliance assessment. In this context we refer to vegetation structural properties as vertical, horizontal and volumetric dimensions, including: canopy height; amount and distribution of vegetation by height; foliage projective cover (FPC); leaf area index (LAI); and above ground biomass. Our aim was to determine if there were significant differences between vegetation structural properties across 11 ecosystem types in Australia as measured by terrestrial laser scanner (TLS) structure metrics. The ecosystems sampled included: mesophyll vineforest, wet-dry tropical savannah, mallee woodland, subtropical eucalypt forest, mulga woodland/grassland, wet eucalypt forest, dry eucalypt forest, tall and wet eucalypt forest, and desert grassland/shrublands. Canopy height, plant area-height profiles and LAI were calculated from consistently processed TLS data using Australia's Terrestrial Ecosystem Research Network's (TERN) Supersites by the TERN AusCover remote sensing field teams from 2012-2015. The Supersites were sampled using standardised field protocols within a core set of 1 ha plots as part of a 5 km x 5 km uniform area using a RIEGL-VZ400 waveform recording TLS. Four to seven scans were completed per plot, with one centre point and then at 25 m away from the centre point along transect lines at 0o, 60o and 240o. Individual foliage profiles were sensitive to spatial variation in the distribution of plant materials. Significant differences were visible between each of the vegetation communities assessed when aggregated to plot and ecosystem type scales. Several of the communities exhibited simple profiles with either grass and shrubs (e.g. desert grassland) or grass and trees (e.g. mallee woodland). Others had multiple vegetation forms at different heights, contributing to the profile (e.g. wet eucalypt forest). The TLS data provide significantly more detail about the relative

  2. Host location and host discrimination behavior of Telenomus isis, an egg parasitoid of the African cereal stem borer Sesamia calamistis.

    Science.gov (United States)

    Chabi-Olaye, A; Schulthess, F; Poehling, H M; Borgemeister, C

    2001-04-01

    In the Republic of Benin, the scelionid egg parasitoid Telenomus isis (Polaszek) is one of the most important control factors of the noctuid maize stem borer Sesamia calamistis. In the present study, the role of various sources of contact kairomones (male or virgin or mated female moths) and of the moth's oviposition substrate (leaf sheath versus filter paper: host plant species) in host location and oviposition behavior of T. isis was investigated in Munger cells, open arenas, and/or Petri dish assays. Furthermore, its ability to distinguish between unparasitized eggs and eggs parasitized by a conspecific female or by the trichogrammatid Lathromeris ovicida was studied. In the Munger cell experiment, T. isis spent more time in moths' odor fields than in the control. There was no difference between virgin and mated females. In the open arena assay, traces left by both the male and female moths acted as contact cues, which elicited an arrestment response in the parasitoid. The residence and patch retention time in the arena with virgin or mated females of S. calamistis was about 4.8 times as long as that with males. The presence of maize leaf sheaths stimulated the oviposition behavior of T. isis when compared to eggs offered on filter paper. During the first 6 hr, more eggs were parasitized on maize leaves, although there was no difference in the final number of offspring between the two substrates. In addition, if eggs of S. calamistis were offered together with different host plant species or alone, maize and sorghum were both more attractive than millet or the egg alone and equally attractive between themselves, indicating that the plant tissue influences host finding of T. isis. Both T. isis and L. ovicida recognized markings of conspecific females, and intraspecific superparasitism was therefore low. Interspecific superparasitism was more than three times higher for L. ovicida than for T. isis, indicating that only T. isis was able to recognize the marking of

  3. Experimental Satellite Quantum Communications.

    Science.gov (United States)

    Vallone, Giuseppe; Bacco, Davide; Dequal, Daniele; Gaiarin, Simone; Luceri, Vincenza; Bianco, Giuseppe; Villoresi, Paolo

    2015-07-24

    Quantum communication (QC), namely, the faithful transmission of generic quantum states, is a key ingredient of quantum information science. Here we demonstrate QC with polarization encoding from space to ground by exploiting satellite corner cube retroreflectors as quantum transmitters in orbit and the Matera Laser Ranging Observatory of the Italian Space Agency in Matera, Italy, as a quantum receiver. The quantum bit error ratio (QBER) has been kept steadily low to a level suitable for several quantum information protocols, as the violation of Bell inequalities or quantum key distribution (QKD). Indeed, by taking data from different satellites, we demonstrate an average value of QBER=4.6% for a total link duration of 85 s. The mean photon number per pulse μ_{sat} leaving the satellites was estimated to be of the order of one. In addition, we propose a fully operational satellite QKD system by exploiting our communication scheme with orbiting retroreflectors equipped with a modulator, a very compact payload. Our scheme paves the way toward the implementation of a QC worldwide network leveraging existing receivers.

  4. Scientific Satellites

    Science.gov (United States)

    1967-01-01

    followed Hale’s into orbit. In 1879, Jules Verne wrote about launching small satellites with a gun possessing a muzzle velocity of 10 000 m/sec (ref. 3...was activated in 1950.11 It was located only a few tens of miles from the spot where Jules Verne had his Baltimore Gun Club fire a manned projectile to...principle, satellites can be launched by a single impulse applied at the Earth’s surface-say, with a large cannon, & la Jules Verne (sec. 8-3). In

  5. ISI Web of Knowledge平台数据库检索方法之浅析

    Institute of Scientific and Technical Information of China (English)

    阮伟娟

    2008-01-01

    本文在对ISI Web of Knowledge(简称WOK) 台作简要介绍的基础上,以其中的综合性数据库Web ofScience和专业性数据库Inspec为例,分析了此平台的几种独特检索方法:Web of Science数据库的Cited ReferenceScarch(被引文献检索),Structure search(化学结构检索);Author Finder(作者甄别)以及Inspec数据库中主题索引机制中的Controlled Indexing(控制词索引).

  6. Examining the Status and Impact Factor of Muslim Scientific Journals in ISI Database: A Bibliometric Study

    Directory of Open Access Journals (Sweden)

    Nurrollah Karami

    2010-09-01

    Full Text Available This paper employs bibliometric method for analyzing the status of journals published in muslim countries in the Journal of Citation Report, an ISI maintained database. The findings indicated that there are 37 journals from 12 muslim countries indexed in JCR. Turkey leads with nine journals indexed. Inter-disciplinary journals constitute the subject area of six journals. Bentham Science Publishers is the most active by publishing 7 journals. Turkey is the only muslim country that has two journals in social sciences. English is the main language in 86.5 percent of the journals studied. Turkish Journal of Earth Sciences has the highest impact factor. The highest citations and citation half-life belonged to Chemical National Compendium from Uzbekistan.

  7. Magnet Design for the ISIS Second Target Station Proton Beam Line

    CERN Document Server

    Thomas, Chris; Jago, Stephen

    2005-01-01

    The ISIS facility, based at the Rutherford Appleton Laboratory in the UK, is an intense source of neutrons and muons for condensed matter research. The accelerator facility delivers an 800 MeV proton beam of 2.5x1013 protons per pulse at 50 Hz to the present target station. As part of a facility upgrade, it is planned to share the source with a second, 10 Hz, target station. The beam line supplying this target will extract from the existing target station beam line. Electromagnetic Finite Element Modelling techniques have been used to design the magnets required to meet the specified beam line optics. Kicker, septum, dipole, quadrupole, and steering magnets are covered. The magnet design process, involving 2D and 3D modelling, the calculation of ideal shims and chamfers, choice of steel, design of conducting coils, handling of heating issues and eddy current effects, is discussed.

  8. SIMULTANEOUS FITS IN ISIS ON THE EXAMPLE OF GRO J1008–57

    Directory of Open Access Journals (Sweden)

    M. Kühnel

    2015-04-01

    Full Text Available Parallel computing and steadily increasing computation speed have led to a new tool for analyzing multiple datasets and datatypes: fitting several datasets simultaneously.  With this technique, physically connected parameters of individual data can be treated as a single parameter by implementing this connection directly into the fit. We discuss the terminology, implementation, and possible issues of simultaneous fits based on the Interactive Spectral Interpretation System (ISIS X-ray data analysis tool. While all data modeling tools in X-ray astronomy in principle allow data to be fitted individually from multiple data sets, the syntax used in these tools is not often well suited for this task. Applying simultaneous fits to the transient X-ray binary GRO J1008–57, we find that the spectral shape is only dependent on X-ray flux. We determine time independent parameters e.g., the folding energy Efold, with unprecedented precision.

  9. In Silico Identification Software (ISIS): A Machine Learning Approach to Tandem Mass Spectral Identification of Lipids

    Energy Technology Data Exchange (ETDEWEB)

    Kangas, Lars J.; Metz, Thomas O.; Isaac, Georgis; Schrom, Brian T.; Ginovska-Pangovska, Bojana; Wang, Luning; Tan, Li; Lewis, Robert R.; Miller, John H.

    2012-05-15

    Liquid chromatography-mass spectrometry-based metabolomics has gained importance in the life sciences, yet it is not supported by software tools for high throughput identification of metabolites based on their fragmentation spectra. An algorithm (ISIS: in silico identification software) and its implementation are presented and show great promise in generating in silico spectra of lipids for the purpose of structural identification. Instead of using chemical reaction rate equations or rules-based fragmentation libraries, the algorithm uses machine learning to find accurate bond cleavage rates in a mass spectrometer employing collision-induced dissocia-tion tandem mass spectrometry. A preliminary test of the algorithm with 45 lipids from a subset of lipid classes shows both high sensitivity and specificity.

  10. Simultaneous fits in ISIS on the example of GRO J1008-57

    CERN Document Server

    Kühnel, Matthias; Kreykenbohm, Ingo; Schwarm, Fritz-Walter; Grossberger, Christoph; Dauser, Thomas; Pottschmidt, Katja; Ferrigno, Carlo; Rothschild, Richard E; Klochkov, Dmitry; Staubert, Rüdiger; Wilms, Jörn

    2016-01-01

    Parallel computing and steadily increasing computation speed have led to a new tool for analyzing multiple datasets and datatypes: fitting several datasets simultaneously. With this technique, physically connected parameters of individual data can be treated as a single parameter by implementing this connection into the fit directly. We discuss the terminology, implementation, and possible issues of simultaneous fits based on the X-ray data analysis tool Interactive Spectral Interpretation System (ISIS). While all data modeling tools in X-ray astronomy allow in principle fitting data from multiple data sets individually, the syntax used in these tools is not often well suited for this task. Applying simultaneous fits to the transient X-ray binary GRO J1008-57, we find that the spectral shape is only dependent on X-ray flux. We determine time independent parameters such as, e.g., the folding energy E_fold, with unprecedented precision.

  11. REVIEW OF PERFORMANCE AND ANALYSIS ISI FLAT PLATE COLLECTOR WITH MODIFIED FLAT PLATE COLLECTOR

    Directory of Open Access Journals (Sweden)

    MR.Y.Y.NANDURKAR

    2012-03-01

    Full Text Available The market of solar water heater of natural circulation type (thermo-siphon is fast growing in India. Initial cost of the solar water heater system at present is high because of store type design. It is necessary to make the product more popular by reducing the cost. This is possible by reducing area of liquid flat plate collector by increasing tube diameter and reducing riser length. Hence it is essential to make solar water heater in affordable range of the general public class. Present work is based on review of comparative performance and analysis of ISI flat plate collector with modified flat plat collector. The paper will be helpful for those who are working in the area of solar water heating system and their use in domestic areas.

  12. The new high field photoexcitation muon spectrometer at the ISIS pulsed neutron and muon source

    CERN Document Server

    Yokoyama, K; Murahari, P; Wang, K; Dunstan, D J; Waller, S P; McPhail, D J; Hillier, A D; Henson, J; Harper, M R; Heathcote, P; Drew, A J

    2016-01-01

    A high power pulsed laser system has been installed on the high magnetic field muon instrument (HiFi) at the ISIS pulsed neutron and muon source, situated at the STFC Rutherford Appleton Laboratory in the UK. The upgrade enables one to perform light-pump muon-probe experiments under a high field, which opens up a brand-new area in the muon spin spectroscopy. In this report we overview the principle of the HiFi Laser system, and describe the newly developed techniques and devices that enable a controlled photoexcitation in the muon instrument. A demonstration experiment illustrates the unique combination of the photoexcited system and avoided level crossing technique.

  13. Citation Analysis of Hepatitis Monthly by Journal Citation Report (ISI), Google Scholar, and Scopus.

    Science.gov (United States)

    Miri, Seyyed Mohammad; Raoofi, Azam; Heidari, Zahra

    2012-09-01

    Citation analysis as one of the most widely used methods of bibliometrics can be used for computing the various impact measures for scholars based on data from citation databases. Journal Citation Reports (JCR) from Thomson Reuters provides annual report in the form of impact factor (IF) for each journal. We aimed to evaluate the citation parameters of Hepatitis Monthly by JCR in 2010 and compare them with GS and Sc. All articles of Hepat Mon published in 2009 and 2008 which had been cited in 2010 in three databases including WoS, Sc and GS gathered in a spreadsheet. The IFs were manually calculated. Among the 104 total published articles the accuracy rates of GS and Sc in recording the total number of articles was 96% and 87.5%. There was a difference between IFs among the three databases (0.793 in ISI [Institute for Scientific Information], 0.945 in Sc and 0.85 GS). The missing rate of citations in ISI was 4% totally. Original articles were the main cited types, whereas, guidelines and clinical challenges were the least ones. None of the three databases succeed to record all articles published in the journal. Despite high sensitivity of GS comparing to Sc, it cannot be a reliable source for indexing since GS has lack of screening in the data collection and low specificity. Using an average of three IFs is suggested to find the correct IF. Editors should be more aware on the role of original articles in increasing IF and the potential efficacy of review articles in long term impact factor.

  14. Lexical and grammatical development in trilingual speakers of isiXhosa, English and Afrikaans

    Directory of Open Access Journals (Sweden)

    Anneke P. Potgieter

    2016-05-01

    Full Text Available Background: There is a dearth of normative data on linguistic development among child speakers of Southern African languages, especially in the case of the multilingual children who constitute the largest part of this population. This inevitably impacts on the accuracy of developmental assessments of such speakers. Already negative lay opinion on the effect of early multilingualism on language development rates could be exacerbated by the lack of developmental data, ultimately affecting choices regarding home and school language policies.Objectives: To establish whether trilinguals necessarily exhibit developmental delay when compared to monolinguals and, if so, whether this delay (1 occurs in terms of both lexical and grammatical development; and (2 in all three the trilinguals’ languages, regardless of input quantity.Method: Focusing on isiXhosa, South African English and Afrikaans, the study involved a comparison of 11 four-year-old developing trilinguals’ acquisition of vocabulary and passive constructions with that of 10 age-matched monolingual speakers of each language.Results: The trilinguals proved to be monolingual-like in their lexical development in the language to which, on average, they had been exposed most over time, that is, isiXhosa. No developmental delay was found in the trilinguals’ acquisition of passive constructions, regardless of the language of testing.Conclusion: As previously found for bilingual development, necessarily reduced quantity of exposure does not hinder lexical development in the trilinguals’ input dominant language. The overall lack of delay in their acquisition of the passive is interpreted as possible evidence of cross-linguistic bootstrapping and support for early multilingual exposure.

  15. Satellite delivery of B-ISDN services

    Science.gov (United States)

    Kwan, R. K.; Price, K. M.; Chitre, D. M.; White, L. W.; Henderson, T. R.

    1992-01-01

    This paper will address the role of technology in the satellite delivery of B-ISDN services. Satellites excel in serving remote users and in providing multicast and broadcast services. Benefits to potential users employing these satellite broadband services will be examined together with their respective network architecture. Two application requirements are then proposed. The critical technologies needed in the realization of these architectures will be identified.

  16. Global navigation satellite systems and their applications

    CERN Document Server

    Madry, Scott

    2015-01-01

    Dr. Madry, one of the world's leading experts in the field, provides in a condensed form a quick yet comprehensive overview of satellite navigation. This book concisely addresses the latest technology, the applications, the regulatory issues, and the strategic implications of satellite navigation systems. This assesses the strengths and weaknesses of satellite navigation networks and review of all the various national systems now being deployed and the motivation behind the proliferation of these systems.

  17. Topomapping of Mars with HRSC images, ISIS, and a commercial stereo workstation

    Science.gov (United States)

    Kirk, R. L.; Howington-Kraus, E.; Galuszka, D.; Redding, B.; Hare, T. M.

    team members to produce DTMs in a consistent coordinate system from a carefully chosen suite of test images [5]. Here, we describe our own approach to HRSC processing and the results we obtained with the test images. We have developed an independent capability for processing of HRSC images at the USGS, based on the approach previously taken with Mars Global Surveyor Mars Orbiter Camera (MGS MOC) images [6]. The chosen approach uses both the USGS digital cartographic system ISIS and the commercial photogrammetric software SOCET SET ( R BAE Systems) and exploits the strengths of each. This capability provides 1 an independent point of comparison for the standard processing, as described here. It also prepares us for systematic mapping with HRSC data, if desired, and makes some useful processing tools (including relatively powerful photometric normalization and photoclinometry software) available to a wide community of ISIS users. ISIS [7] provides an end-to-end system for the analysis of digital images and production of maps from them that is readily extended to new missions. Its stereo capabilities are, however, limited. SOCET SET [8] is tailored to aerial and Earth-orbital imagery but provides a complete workflow with modules for bundle adjustment (MST), automatic stereomatching (ATE), and interactive quality control/editing of DTMs with stereo viewing (ITE). Our processing approach for MOC and other stereo datasets has been to use ISIS to ingest images in an archival format, decompress them as necessary, and perform instrument-specific radiometric calibration. Software written in ISIS is used to translate the image and, more importantly, orientation parameters and other metadata, to the formats understood by SOCET SET. The commercial system is then used for "three-dimensional" processing: bundle-adjustment (including measurement of needed control points), DTM generation, and DTM editing. Final steps such as orthrectification and mosaicking of images can be performed

  18. "Unomathotholo" or "i-Radio?" Factors Predicting the Use of English Loanwords among L1 isiXhosa--L2 English Bilinguals

    Science.gov (United States)

    Bylund, Emanuel

    2014-01-01

    This study examines the use of English loanwords in L1 isiXhosa-L2 English bilinguals living in Cape Town, South Africa. The specific aim of the study is to investigate which individual background factors may increase or reduce the presence of English loanwords in a L1 isiXhosa speaker's repertoire. Data on English loanword use and individual…

  19. Introduction to Satellite Communications Technology for NREN

    Science.gov (United States)

    Stone, Thom

    2004-01-01

    NREN requirements for development of seamless nomadic networks necessitates that NREN staff have a working knowledge of basic satellite technology. This paper addresses the components required for a satellite-based communications system, applications, technology trends, orbits, and spectrum, and hopefully will afford the reader an end-to-end picture of this important technology.

  20. A SELF-ADAPTIVE WEIGHT-BASED ROUTING ALGORITHM IN LEO SATELLITE NETWORK%LEO卫星网络中一种自适应权值路由算法

    Institute of Scientific and Technical Information of China (English)

    江玉洁; 姚晔; 梁旭文

    2013-01-01

    针对LEO卫星网络拓扑动态时变的特点,提出一种自适应权值路由算法.该算法综合考虑了路由的时延和切换频率,既能保证低代价路由的选择优先权,又兼顾了网络流量的平衡.采用地面离线计算方式,简化了星上路由计算.另外,采用节点实时状态与权值路由表相结合的方式选择分组路径,使其对网络实时状态具备一定的自适应性.通过仿真分析证明,该算法在应对拥塞时的时延和时延抖动方面的性能表现良好.%According to the characteristics of LEO satellite network in its topology dynamic time-variant, we propose a novel self-adaptive weights-based routing algorithm. The algorithm takes in to account comprehensively the routing delays and handover frequency and balances between the selection priority of low-cost routing and the equilibrium of networks traffic. With the help of off-line computing on the ground, we simplify the computing complexity of the routing in the satellite. Besides, the algorithm selects the packet path by combining the node real-time status with weighted routing table, this makes the algorithm has self-adaptive property to certain extent on real-time status of the network. From the simulation analyses it is proved that the algorithm performs well in tackling with the delay and its jitters when congestion happened in the network.

  1. Evaluating ADS, ISI Web of Knowledge and Scopus in the Context of Two Astronomy Libraries in Spain

    Science.gov (United States)

    Gomez, M.; Merida Martín, F.

    2007-10-01

    We present the results of a comparative analysis of ADS, ISI Web of Knowledge and Scopus in the context of two astronomical libraries as well as the results of a patron survey conducted to determine how patrons use these services to get the information they need.

  2. Word recognition strategies amongst isiXhosa/English bilingual learners: The interaction of orthography and language of learning and teaching

    Directory of Open Access Journals (Sweden)

    Tracy Probert

    2016-03-01

    Full Text Available Word recognition is a major component of fluent reading and involves an interaction of language structure, orthography, and metalinguistic skills. This study examined reading strategies in isiXhosa and the transfer of these strategies to an additional language, English. IsiXhosa was chosen because of its agglutinative structure and conjunctive orthography. Data was collected at two schools which differed with regards to their language of learning and teaching (LoLT in the first three years of schooling: isiXhosa and English respectively. Participants completed a wordand pseudo-word reading aloud task in each of two languages which hypothetically impose different cognitive demands. Skills transfer occurs to a limited extent when the language of first literacy uses a transparent orthography, but is less predictable when the language of first literacy uses an opaque orthography. We show that although there is transfer of word recognition strategies from transparent to deep orthographies, felicitous transfer is limited to sublexical strategies; infelicitous transfer also occurs when lexical strategies are transferred in problematic ways. The results support the contention that reading strategies and cognitive skills are fine tuned to particular languages. This study emphasises that literacies in different languages present readers with different structural puzzles which require language-particular suites of cognitive reading skills. Keywords: Foundation phase education; multilingual education; reading; word recognition; automaticity; isiXhosa reading

  3. Risiko Kegagalan pada Kualitas Produksi Air Minum Isi Ulang di Kecamatan Sukolilo Surabaya Menggunakan Failure Mode and Effect Analysis (FMEA

    Directory of Open Access Journals (Sweden)

    Egy Asri Yassin Utami

    2017-01-01

    Full Text Available Kebutuhan manusia terhadap air minum yang layak konsumsi semakin lama semakin berkembang sebanding dengan perkembangan penduduk yang kian lama kian meningkat. Untuk dapat memenuhi kebutuhan air minum sehari-hari, banyak industri yang membuka usaha air minum diantaranya adalah adanya depot air minum isi ulang (DAMIU. Pemilihan depot air minum isi ulang sebagai alternatif air minum menjadi risiko yang dapat membahayakan kesehatan jika kualitas depot air minum isi ulang masih diragukan. Penilitian ini menggunakan metode FMEA (Failure Mode and Effect Analysis untuk mencari prioritas terjadinya kegagalan dalam proses pengolahan air minum isi ulang. Risiko-risiko yang didapat harus memiliki nilai agar terukur sehingga ditemukan prioritas penanganan dan dicari upaya untuk perbaikan. Penilaian tersebut dikenal dengan nilai RPN (Risk Priority Number yaitu hasil pengalian dari tingkat keparahan (severity, frekuensi kejadian (occurrence dan tingkat deteksi (detection. Berdasarkan hasil analisa dan identifikasi menggunakan metode FMEA diketahui bahwa kegagalan yang terjadi pada sistem UV dengan 3 prioritas tertinggi yaitu penggunaan UV dengan nilai RPN 100, waktu kontak UV dengan nilai RPN 100 dan penggantian filter awal dengan nilai RPN 64. Pada sistem UV dan ozon, 3 prioritas tertinggi yaitu waktu kontak sistem ozon, waktu kontak UV dan penggunaan UV dengan masing-masing nilai RPN yaitu 100. Sedangkan pada sistem UV, ozon dan RO (Reverse Osmosis 3 prioritas tertinggi sama seperti dengan sistem UV dan ozon dengan nilai RPN yang berbeda yaitu lama pengoperasian dengan nilai 100, waktu kontak dan kesesuaian penggunaan UV dengan nilai 64.

  4. EVALUASI PROGRAM KURIKULUM BERDASARKAN STANDAR ISI, STANDAR PROSES, DAN STANDAR KOMPETENSI LULUSAN DI SDN PISANGAN TIMUR 10 PAGI

    OpenAIRE

    Rahmawati, Desi; Anggraini, Arlyta Dwi

    2017-01-01

    enelitian ini bertujuan untuk mengetahui pelaksanaan Kurikulum Tingkat Satuan Pendidikan (KTSP) di Pisangan Timur 10 Pagi. Metode penelitian dalam penelitian ini adalah deskriptif evaluatif dengan model CIPP (Context, Input, Process, Product). Peneliti menggunakan model CIPP karena pembagian keempat komponen yang ada memudahkan peneliti dalam mengevaluasi standar isi, standar proses, dan standar kompetensi lulusan di tempat penelitian. Penelitian yang dilaksanakan memberikan beberapa gambaran...

  5. Impact of "JOBM": ISI Impact Factor Places the "Journal of Organizational Behavior Management" Third in Applied Psychology

    Science.gov (United States)

    Hantula, Donald A.

    2006-01-01

    The ISI Impact Factor for "JOBM" is 1.793, placing it third in the JCR rankings for journals in applied psychology with a sharply accelerating linear trend over the past 5 years. This article reviews the Impact Factor and raises questions regarding its reliability and validity and then considers a citation analysis of "JOBM" in light of the…

  6. Impact of "JOBM": ISI Impact Factor Places the "Journal of Organizational Behavior Management" Third in Applied Psychology

    Science.gov (United States)

    Hantula, Donald A.

    2006-01-01

    The ISI Impact Factor for "JOBM" is 1.793, placing it third in the JCR rankings for journals in applied psychology with a sharply accelerating linear trend over the past 5 years. This article reviews the Impact Factor and raises questions regarding its reliability and validity and then considers a citation analysis of "JOBM" in light of the…

  7. Integration of Mobil Satellite and Cellular Systems

    Science.gov (United States)

    Drucker, E. H.; Estabrook, P.; Pinck, D.; Ekroot, L.

    1993-01-01

    By integrating the ground based infrastructure component of a mobile satellite system with the infrastructure systems of terrestrial 800 MHz cellular service providers, a seamless network of universal coverage can be established.

  8. Satellite Communications Using Commercial Protocols

    Science.gov (United States)

    Ivancic, William D.; Griner, James H.; Dimond, Robert; Frantz, Brian D.; Kachmar, Brian; Shell, Dan

    2000-01-01

    NASA Glenn Research Center has been working with industry, academia, and other government agencies in assessing commercial communications protocols for satellite and space-based applications. In addition, NASA Glenn has been developing and advocating new satellite-friendly modifications to existing communications protocol standards. This paper summarizes recent research into the applicability of various commercial standard protocols for use over satellite and space- based communications networks as well as expectations for future protocol development. It serves as a reference point from which the detailed work can be readily accessed. Areas that will be addressed include asynchronous-transfer-mode quality of service; completed and ongoing work of the Internet Engineering Task Force; data-link-layer protocol development for unidirectional link routing; and protocols for aeronautical applications, including mobile Internet protocol routing for wireless/mobile hosts and the aeronautical telecommunications network protocol.

  9. Data collection method for delay tolerant wireless sensor network by satellite communication%一种结合卫星通信的容迟无线传感网数据收集方法

    Institute of Scientific and Technical Information of China (English)

    罗青春; 彭伟; 郦苏丹; 王勇

    2011-01-01

    Under the research background of sparse wireless sensor network deploying in wide area, this paper designed a data collection architecture, and orders were sent to sleeping nodes in destined area by satellite Ceocasting. Data Mule collected nodes' data and got back by satellite, and layout the Data Mule's movement path, a convex hull-based algorithm and communication protocol. Simulation results show that this method can solve the data collection problem in sparse wireless sensor network under complex environment, and have good performance.%以广域部署的稀疏无线传感网为研究背景,给出一种无线传感网数据收集系统结构,利用卫星(Geocasting方式向指定地域的处于睡眠状态的无线传感器节点发送指令,利用Data Mule收集节点的数据并通过卫星回传,对Data Mule的运动路径进行了规划,提出了一种基于凸包的算法,并设计了该系统的通信协议.仿真结果表明,该方法能有效解决广域稀疏无线传感网在复杂环境中数据收集的难题,有良好的性能.

  10. 卫星教学资源通过城域网传输的方案与实现%Project of Transmitting Satellite Video Teaching Resources through Metropolitan Area Network

    Institute of Scientific and Technical Information of China (English)

    薛曼芳

    2012-01-01

      The paper discusses how to use streaming media technology, satellite reception technology and existing computer, network, software and hardware resources to achieve efficient transmission, sharing and centralized management of satellite video teaching resource via Metropolitan Area Network (MAN). This project addresses the issues including uneven allocation of educational resources, difficulties in equipment management and shortage of IT supporting professionals during the implementation process of modern remote educational project of elementary and middle school in countryside. It also improves the level of information technology of education.%  探讨了如何利用流媒体技术、卫星接收技术及现有电脑网络软硬件资源,实现卫星视频教学资源在城域网内的有效传输、分享和集中管理,解决在“农村中小学现代远程教育工程”实施过程中,教育资源分配不均衡、资源和设备管理难、专业信息人员缺乏等问题,提高了教育信息化水平。

  11. Daphnia magna's sense of competition: intra-specific interactions (ISI) alter life history strategies and increase metals toxicity.

    Science.gov (United States)

    Gust, Kurt A; Kennedy, Alan J; Melby, Nicolas L; Wilbanks, Mitchell S; Laird, Jennifer; Meeks, Barbara; Muller, Erik B; Nisbet, Roger M; Perkins, Edward J

    2016-08-01

    This work investigates whether the scale-up to multi-animal exposures that is commonly applied in genomics studies provides equivalent toxicity outcomes to single-animal experiments of standard Daphnia magna toxicity assays. Specifically, we tested the null hypothesis that intraspecific interactions (ISI) among D. magna have neither effect on the life history strategies of this species, nor impact toxicological outcomes in exposure experiments with Cu and Pb. The results show that ISI significantly increased mortality of D. magna in both Cu and Pb exposure experiments, decreasing 14 day LC50 s and 95 % confidence intervals from 14.5 (10.9-148.3) to 8.4 (8.2-8.7) µg Cu/L and from 232 (156-4810) to 68 (63-73) µg Pb/L. Additionally, ISI potentiated Pb impacts on reproduction eliciting a nearly 10-fold decrease in the no-observed effect concentration (from 236 to 25 µg/L). As an indication of environmental relevance, the effects of ISI on both mortality and reproduction in Pb exposures were sustained at both high and low food rations. Furthermore, even with a single pair of Daphnia, ISI significantly increased (p history strategy. Given these results we reject the null hypothesis and conclude that results from scale-up assays cannot be directly applied to observations from single-animal assessments in D. magna. We postulate that D. magna senses chemical signatures of conspecifics which elicits changes in life history strategies that ultimately increase susceptibility to metal toxicity.

  12. Satellites for Commonwealth Education: Some Policy Issues. Case Studies: AUSSAT, Australia; Knowledge Network, Canada; INSAT, India; University of the South Pacific; University of the West Indies.

    Science.gov (United States)

    Bates, A. W.

    This report presents case studies on the use of satellites for education in five Commonwealth countries: Australia, Canada, India, Fiji, and Jamaica. Information provided in each of the case studies includes geography, production, the distribution system, regulation and management, and costs. Additional information given for the Australian…

  13. Analysis of coherent satellite communication systems in the presence of interference and noise

    Science.gov (United States)

    Huang, T.-C.; Omura, J. K.; Lindsey, W. C.

    1981-01-01

    The general analysis presented can be used to evaluate the performance of M-ary phase shift keying (MPSK) used over a nonlinear satellite channel in the presence of interference (CW tone and ISI) and channel noise. The numerical evaluation is based on the classical moment technique for approximating the probability distribution from moments of a random variable. The mathematical formulation of error probabilities of MPSK signals transmitted over nonlinear satellite repeaters is presented to include the effect of CW tone interference as well as the intersymbol interference. The approach is general and can be extended to include the effect of the synchronization.

  14. Load Balancing Multicasting Algorithm Based on Timescales for LEO Satellite Network%面向LEO卫星通信网络基于时间尺度的负载均衡组播路由算法

    Institute of Scientific and Technical Information of China (English)

    马骁; 安建伟

    2015-01-01

    The purpose of this paper is aiming to build a low cost multicasting tree on a global coverage LEO satellite communication network. In this paper, the authors proposed a load balancing multicasting algorithm based on timescales for LEO satellite network ( LBMT) . LBMT collect the occupying state and calculate comparison cost of corresponding link and aiming to minimize the comparison cost rather than cost or delay of the tree. Several proposed multicasting algorithms aim for minimizing the delay or cost of multicast tree. However, the whole network traffic is not evenly distributed, multicast algorithms have been proposed usually deteriorate the network status under high load conditions because those algorithms often take the initiative to avoid the busy link. Simulation results shows that LBMT can decrease data loss rate under high traffic conditions with a little increase of transmission delay. Simulation results shows that LBMT can decrease data loss rate under high traffic conditions with a little increase of transmission delay. It can be concluded that the multicasting tree built by LBMT can efficiently avoid the busy ISLs and pick the idle ISLs above the developing region. The idle ISLs can be utilized by LBMT and the traffic of network is more balanced.%为了在全球覆盖的低地球轨道( low earth orbit,LEO)卫星通信网络下,获得较小开销的组播树,而非仅仅是降低树开销或最小传输时延,提出一种面向LEO卫星通信网络的基于时间尺度的多度量负载均衡组播路由算法( load balancing multicasting algorithm based on timescales for LEO satellite network,LBMT),通过获取星间链路( inter-satellite links, ISL)的状态信息并通过设计的评价链路状态“比对开销”,建立较小“比对开销”组播树。已提出的面向LEO卫星网路的组播路由算法通常目标为最小化组播树的树开销或传输时延,然而LEO卫星网络的全网流量并非均匀分布,已提出的组播算

  15. Integration of mobile satellite and cellular systems

    Science.gov (United States)

    Drucker, Elliott H.; Estabrook, Polly; Pinck, Deborah; Ekroot, Laura

    1993-01-01

    By integrating the ground based infrastructure component of a mobile satellite system with the infrastructure systems of terrestrial 800 MHz cellular service providers, a seamless network of universal coverage can be established. Users equipped for both cellular and satellite service can take advantage of a number of features made possible by such integration, including seamless handoff and universal roaming. To provide maximum benefit at lowest posible cost, the means by which these systems are integrated must be carefully considered. Mobile satellite hub stations must be configured to efficiently interface with cellular Mobile Telephone Switching Offices (MTSO's), and cost effective mobile units that provide both cellular and satellite capability must be developed.

  16. Satellite Communication and Long Distance Education

    Directory of Open Access Journals (Sweden)

    Hafied Cangara

    2016-02-01

    Full Text Available Since Indonesia introduced communication satellite for telecommunication network, the satellite has brought a number of advantages for national development in various areas, such as telephone network, mass media development, business, education, politics, security and national defence as well as regional and international cooperation. In education, satellite communication could be used for long-distance learning as implemented by 13 state universities in eastern parts of Indonesia. It is also possible to develop the Open University System in teaching and learning process, particularly since the internet technology has been intensively used

  17. The Philosophical Allegory of the Isis Figure in Beroaldo’s Commentary on Apuleius’ Golden Ass

    Directory of Open Access Journals (Sweden)

    Sonja Weiss

    2012-12-01

    Full Text Available The article aims to identify the philosophical digressions in Philippo Beroaldo’s encyclopaedic commentary, and to understand them in view of the author’s general approach to Apuleius’ Golden Ass. As Beroaldo deliberately abstains from writing a philosophical commentary, it is no surprise that he gives merely a historical (and yet personally coloured survey of the tale of Cupid and Psyche and its tradition of various moralistic, religious, and philosophical interpretations. For him, Apuleius’ text is principally a moral allegory. On the other hand, the subject of Book 11 (the so-called Book of Isis, centred around Lucius’ spiritual as well as physical transformation, leads him to topics which he necessarily approaches as an erudite of his era, heavily influenced by the Christian Neoplatonism. His commentary on some passages of truly mystical character evinces an ambiguity attested at the very beginning, where Beroaldo, apart from the generally accepted moralistic interpretation, briefly mentions another way of reading the text: reading it as veiled Pythagorean and Platonic doctrines of the regeneration and transmigration of the soul. Indeed, Beroaldo’s interest in Pythagorean philosophy and its classical proponents is also evident in some of his other works, and the Commentary lacks no hints of these secret doctrines, which spring up quite unexpectedly sometimes. Even more surprising is Beroaldo’s reserve, once he broaches this subject, protected by what he terms fides silentii. He cherishes this expression to the point which makes us wonder whether his commentary merely reflects the encyclopaedic rigour of a teacher, eager to present a text from all points of view, or displays the emulous thought of a kindred spirit (a point made in some modern studies, restrained from saying more. Indeed, Beroaldo’s interpretation of the goddess Isis figure as an ancient manifestation of the one God corroborates the latter assumption. Also

  18. Heart Monitoring By Satellite

    Science.gov (United States)

    1978-01-01

    The ambulance antenna shown is a specially designed system that allows satellite-relayed two-way communications between a moving emergency vehicle and a hospital emergency room. It is a key component of a demonstration program aimed at showing how emergency medical service can be provided to people in remote rural areas. Satellite communication permits immediate, hospital- guided treatment of heart attacks or other emergencies by ambulance personnel, saving vital time when the scene of the emergency is remote from the hospital. If widely adopted, the system could save tens of thousands of lives annually in the U.S. alone, medical experts say. The problem in conventional communication with rural areas is the fact that radio signals travel in line of sight. They may be blocked by tall buildings, hills and mountains, or even by the curvature of the Earth, so signal range is sharply limited. Microwave relay towers could solve the problem, but a complete network of repeater towers would be extremely expensive. The satellite provides an obstruction-free relay station in space.

  19. Long-term MAX-DOAS network observations of NO2 in Russia and Asia (MADRAS) during the period 2007-2012: instrumentation, elucidation of climatology, and comparisons with OMI satellite observations and global model simulations

    Science.gov (United States)

    Kanaya, Y.; Irie, H.; Takashima, H.; Iwabuchi, H.; Akimoto, H.; Sudo, K.; Gu, M.; Chong, J.; Kim, Y. J.; Lee, H.; Li, A.; Si, F.; Xu, J.; Xie, P.-H.; Liu, W.-Q.; Dzhola, A.; Postylyakov, O.; Ivanov, V.; Grechko, E.; Terpugova, S.; Panchenko, M.

    2014-08-01

    We conducted long-term network observations using standardized Multi-Axis Differential optical absorption spectroscopy (MAX-DOAS) instruments in Russia and ASia (MADRAS) from 2007 onwards and made the first synthetic data analysis. At seven locations (Cape Hedo, Fukue and Yokosuka in Japan, Hefei in China, Gwangju in Korea, and Tomsk and Zvenigorod in Russia) with different levels of pollution, we obtained 80 927 retrievals of tropospheric NO2 vertical column density (TropoNO2VCD) and aerosol optical depth (AOD). In the technique, the optimal estimation of the TropoNO2VCD and its profile was performed using aerosol information derived from O4 absorbances simultaneously observed at 460-490 nm. This large data set was used to analyze NO2 climatology systematically, including temporal variations from the seasonal to the diurnal scale. The results were compared with Ozone Monitoring Instrument (OMI) satellite observations and global model simulations. Two NO2 retrievals of OMI satellite data (NASA ver. 2.1 and Dutch OMI NO2 (DOMINO) ver. 2.0) generally showed close correlations with those derived from MAX-DOAS observations, but had low biases of up to ~50%. The bias was distinct when NO2 was abundantly present near the surface and when the AOD was high, suggesting a possibility of incomplete accounting of NO2 near the surface under relatively high aerosol conditions for the satellite observations. Except for constant biases, the satellite observations showed nearly perfect seasonal agreement with MAX-DOAS observations, suggesting that the analysis of seasonal features of the satellite data were robust. Weekend reduction in the TropoNO2VCD found at Yokosuka and Gwangju was absent at Hefei, implying that the major sources had different weekly variation patterns. While the TropoNO2VCD generally decreased during the midday hours, it increased exceptionally at urban/suburban locations (Yokosuka, Gwangju, and Hefei) during winter. A global chemical transport model, MIROC

  20. The power relay satellite

    Science.gov (United States)

    Glaser, Peter E.

    The availability and use of renewable energy sources compatible with reducing risks to the global environment are key to sustainable development. Large-scale, renewable energy resources at undeveloped or underutilized sites are potentially available on several continents. The Power Relay Satellite (PRS) concept has the potential to access these remote energy resources by coupling primary electricity generation from terrestrial transmission lines. A global PRS network can be envisioned to provide a high degree of flexibility for supplying energy demands worldwide with wireless power transmitted from sites on Earth to geosynchronous orbit and then reflected to receivers interfacing with terrestrial power transmision networks. Past developments in wireless power transmission (WPT) are reviewed and recent successful results are noted. The origins of the PRS concept, and a possible configuration are discussed, principles of WPT at microwave frequencies, functional requirements, and system design contraints are outlined, and space transportation concepts presented. PRS assessments including applicable technologies, economic projections, and societal issues are highlighted. It is concluded that the PRS provides a promising option to access renewable resources at great distances from major markets, and represents an important stage in the future development in the future of solar power satellites.

  1. ISI Web of Knowledge新增分析工具Results Analysis探讨 --BIOSIS Previews检索实践%Results Analysis of ISI Web of Knowledge: its' usage introduction

    Institute of Scientific and Technical Information of China (English)

    张轶群

    2005-01-01

    针对检索结果的信息分析和信息挖掘的分析工具Results Analysis是ISI Web of Knowledge于2004年新增的服务功能.以BIOSIS Previews为检索实例,详细探讨ResultsAnalysis分析工具的使用方法和功能,并提出改进的建议.

  2. Deep-penetration calculation for the ISIS target station shielding using the MARS Monte Carlo code

    CERN Document Server

    Nunomiya, T; Nakamura, T; Nakao, N

    2002-01-01

    A calculation of neutron penetration through a thick shield was performed with a three-dimensional multi-layer technique using the MARS14(02) Monte Carlo code to compare with the experimental shielding data in 1998 at the ISIS spallation neutron source facility. In this calculation, secondary particles from a tantalum target bombarded by 800-MeV protons were transmitted through a bulk shield of approximately 3-m-thick iron and 1-m-thick concrete. To accomplish this deep-penetration calculation with good statistics, the following three techniques were used in this study. First, the geometry of the bulk shield was three-dimensionally divided into several layers of about 50-cm thickness, and a step-by-step calculation was carried out to multiply the number of penetrated particles at the boundaries between the layers. Second, the source particles in the layers were divided into two parts to maintain the statistical balance on the spatial-flux distribution. Third, only high-energy particles above 20 MeV were trans...

  3. Investigation of ISIS and Brookhaven National Laboratory ion source electrodes after extended operationa)

    Science.gov (United States)

    Lettry, J.; Alessi, J.; Faircloth, D.; Gerardin, A.; Kalvas, T.; Pereira, H.; Sgobba, S.

    2012-02-01

    Linac4 accelerator of Centre Européen de Recherches Nucléaires is under construction and a RF-driven H- ion source is being developed. The beam current requirement for Linac4 is very challenging: 80 mA must be provided. Cesiated plasma discharge ion sources such as Penning or magnetron sources are also potential candidates. Accelerator ion sources must achieve typical reliability figures of 95% and above. Investigating and understanding the underlying mechanisms involved with source failure or ageing is critical when selecting the ion source technology. Plasma discharge driven surface ion sources rely on molybdenum cathodes. Deformation of the cathode surfaces is visible after extended operation periods. A metallurgical investigation of an ISIS ion source is presented. The origin of the deformation is twofold: Molybdenum sputtering by cesium ions digs few tenths of mm cavities while a growth of molybdenum is observed in the immediate vicinity. The molybdenum growth under hydrogen atmosphere is hard and loosely bound to the bulk. It is, therefore, likely to peel off and be transported within the plasma volume. The observation of the cathode, anode, and extraction electrodes of the magnetron source operated at BNL for two years are presented. A beam simulation of H-, electrons, and Cs- ions was performed with the IBSimu code package to qualitatively explain the observations. This paper describes the operation conditions of the ion sources and discusses the metallurgical analysis and beam simulation results.

  4. Investigation of ISIS and Brookhaven National Laboratory ion source electrodes after extended operation

    Energy Technology Data Exchange (ETDEWEB)

    Lettry, J.; Gerardin, A.; Pereira, H.; Sgobba, S. [CERN, 1211 Geneva 23 (Switzerland); Alessi, J. [BNL, P.O. Box 5000, Upton, New York 11973-5000 (United States); Faircloth, D. [RAL, Harwell Oxford, Didcot OX11 0QX (United Kingdom); Kalvas, T. [University of Jyvaskyla, P.O.Box 35, FI-40014 (Finland)

    2012-02-15

    Linac4 accelerator of Centre Europeen de Recherches Nucleaires is under construction and a RF-driven H{sup -} ion source is being developed. The beam current requirement for Linac4 is very challenging: 80 mA must be provided. Cesiated plasma discharge ion sources such as Penning or magnetron sources are also potential candidates. Accelerator ion sources must achieve typical reliability figures of 95% and above. Investigating and understanding the underlying mechanisms involved with source failure or ageing is critical when selecting the ion source technology. Plasma discharge driven surface ion sources rely on molybdenum cathodes. Deformation of the cathode surfaces is visible after extended operation periods. A metallurgical investigation of an ISIS ion source is presented. The origin of the deformation is twofold: Molybdenum sputtering by cesium ions digs few tenths of mm cavities while a growth of molybdenum is observed in the immediate vicinity. The molybdenum growth under hydrogen atmosphere is hard and loosely bound to the bulk. It is, therefore, likely to peel off and be transported within the plasma volume. The observation of the cathode, anode, and extraction electrodes of the magnetron source operated at BNL for two years are presented. A beam simulation of H{sup -}, electrons, and Cs{sup -} ions was performed with the IBSimu code package to qualitatively explain the observations. This paper describes the operation conditions of the ion sources and discusses the metallurgical analysis and beam simulation results.

  5. Investigation of ISIS and Brookhaven National Laboratory ion source electrodes after extended operation

    Energy Technology Data Exchange (ETDEWEB)

    Lettry J.; Alessi J.; Faircloth, D.; Gerardin, A.; Kalvas, T.; Pereira, H.; Sgobba, S.

    2012-02-23

    Linac4 accelerator of Centre Europeen de Recherches Nucleaires is under construction and a RF-driven H{sup -} ion source is being developed. The beam current requirement for Linac4 is very challenging: 80 mA must be provided. Cesiated plasma discharge ion sources such as Penning or magnetron sources are also potential candidates. Accelerator ion sources must achieve typical reliability figures of 95% and above. Investigating and understanding the underlying mechanisms involved with source failure or ageing is critical when selecting the ion source technology. Plasma discharge driven surface ion sources rely on molybdenum cathodes. Deformation of the cathode surfaces is visible after extended operation periods. A metallurgical investigation of an ISIS ion source is presented. The origin of the deformation is twofold: Molybdenum sputtering by cesium ions digs few tenths of mm cavities while a growth of molybdenum is observed in the immediate vicinity. The molybdenum growth under hydrogen atmosphere is hard and loosely bound to the bulk. It is, therefore, likely to peel off and be transported within the plasma volume. The observation of the cathode, anode, and extraction electrodes of the magnetron source operated at BNL for two years are presented. A beam simulation of H{sup -}, electrons, and Cs{sup -} ions was performed with the IBSimu code package to qualitatively explain the observations. This paper describes the operation conditions of the ion sources and discusses the metallurgical analysis and beam simulation results.

  6. Investigation of ISIS and Brookhaven National Laboratory ion source electrodes after extended operation.

    Science.gov (United States)

    Lettry, J; Alessi, J; Faircloth, D; Gerardin, A; Kalvas, T; Pereira, H; Sgobba, S

    2012-02-01

    Linac4 accelerator of Centre Européen de Recherches Nucléaires is under construction and a RF-driven H(-) ion source is being developed. The beam current requirement for Linac4 is very challenging: 80 mA must be provided. Cesiated plasma discharge ion sources such as Penning or magnetron sources are also potential candidates. Accelerator ion sources must achieve typical reliability figures of 95% and above. Investigating and understanding the underlying mechanisms involved with source failure or ageing is critical when selecting the ion source technology. Plasma discharge driven surface ion sources rely on molybdenum cathodes. Deformation of the cathode surfaces is visible after extended operation periods. A metallurgical investigation of an ISIS ion source is presented. The origin of the deformation is twofold: Molybdenum sputtering by cesium ions digs few tenths of mm cavities while a growth of molybdenum is observed in the immediate vicinity. The molybdenum growth under hydrogen atmosphere is hard and loosely bound to the bulk. It is, therefore, likely to peel off and be transported within the plasma volume. The observation of the cathode, anode, and extraction electrodes of the magnetron source operated at BNL for two years are presented. A beam simulation of H(-), electrons, and Cs(-) ions was performed with the IBSimu code package to qualitatively explain the observations. This paper describes the operation conditions of the ion sources and discusses the metallurgical analysis and beam simulation results.

  7. ISI Bibliometric profile of Universidad de Concepción School of Dentistry, 1989-2012.

    Directory of Open Access Journals (Sweden)

    Javier Moraga

    2013-04-01

    Full Text Available Aim: To characterize personal, institutional or national scientific production is a need to understand and improve the generation of knowledge. The aim of this study is to describe the bibliometric profile of ISI publications related of Universidad de Concepción School of Dentistry during 1989-2012 timespan.Matherial and methods: Bibliometric study. A search on Web of Knowledge of Thomson Reuters for Science Citation Index Expanded database was perfomed, about the scientific productivity of Universidad de Concepción School of Dentistry during 1989-2012 period. The analyzed variables were the number of publications, cites, magazines on which they were published, authors, institutions and coauthor countries.Results: Thirty nine articles were identified. These articles were cited in 266 opportunities (6,82 cites per article and h-index of 10. In relation with journals, stands out Oral Surgery Oral Medicine Oral Pathology Oral Radiology and Endodontology (21.9%, Journal of Oral Pathology Medicine (12.2%, and International Journal of Morphology (7.3%. More productive authors were Rojas (13, Martínez (11 y Brethauer (9. 48,72% of publications was concentrated in last five-years and 69.23% in last ten-years.Conclusions: Universidad de Concepción School of Dentistry scientific production is poor, being observed an increase during the last 5 years.

  8. Psychiatric symptoms and disorders among Yazidi children and adolescents immediately after forced migration following ISIS attacks.

    Science.gov (United States)

    Ceri, Veysi; Özlü-Erkilic, Zeliha; Özer, Ürün; Yalcin, Murat; Popow, Christian; Akkaya-Kalayci, Türkan

    2016-09-01

    The aim of the present study was to evaluate psychiatric problems and disorders among Yazidi Kurd refugee children and adolescents, who were assessed immediately after their forced migration following life-threatening attacks by ISIS terrorists. We retrospectively analyzed the psychiatric assessments of 38 Yazidi children and adolescents (age 2-18, mean 12 years, m:f = 16:22), which were performed upon their arrival at the refugee camp. All children and adolescents exhibited psychiatric problems and disorders, 50 % had one, and 50 % had more than one. The most relevant problems were disturbed sleeping (71 % of children), followed by depression (36.8 %), conversion disorders (28.9 %), adjustment (21.8 %), acute (18.4 %) and posttraumatic stress (PTSD, 10.5 %) disorders, and non-organic enuresis (18.4 %). Our study confirms the results of previous studies, asserting that refugee children and adolescents do not just suffer from PTSD but from various other problems that are already present in the first days of resettlement. Children and adolescents living in refugee camps urgently need psychosocial support.

  9. Performance of mismatched Viterbi receiver on satellite channels

    Science.gov (United States)

    Divsalar, D.; Omura, J. K.

    1979-01-01

    This paper presents an analysis of a satellite communication system using a Viterbi receiver. Here we have a bandlimited nonlinear channel where both uplink and downlink are taken into account as well as the effect of Intersymbol Interference, phase and time synchronization errors. In order that ISI can be combatted effectively, we use a Viterbi demodulator which is designed for the satellite channel when there is no uplink noise. The Viterbi demodulator for the channels with large memory is too complex to be implemented. To reduce the complexity, a Viterbi demodulator with memory shorter than the true channel memory is used. The objective of this paper is to analyze the performance degradation of this 'Mismatched Viterbi Receiver' due to the uplink noise and memory truncation, and to understand how the time and phase synchronization errors influence the performance.

  10. An introduction to optimal satellite range scheduling

    CERN Document Server

    Vázquez Álvarez, Antonio José

    2015-01-01

    The satellite range scheduling (SRS) problem, an important operations research problem in the aerospace industry consisting of allocating tasks among satellites and Earth-bound objects, is examined in this book. SRS principles and solutions are applicable to many areas, including: Satellite communications, where tasks are communication intervals between sets of satellites and ground stations Earth observation, where tasks are observations of spots on the Earth by satellites Sensor scheduling, where tasks are observations of satellites by sensors on the Earth. This self-contained monograph begins with a structured compendium of the problem and moves on to explain the optimal approach to the solution, which includes aspects from graph theory, set theory, game theory and belief networks. This book is accessible to students, professionals and researchers in a variety of fields, including: operations research, optimization, scheduling theory, dynamic programming and game theory. Taking account of the distributed, ...

  11. Proximity and the evolution of collaboration networks: evidence from research and development projects within the global navigation satellite system (GNSS) industry

    NARCIS (Netherlands)

    Balland, P.M.A.

    2011-01-01

    This paper analyses the influence of proximity on the evolution of collaboration networks. It determines empirically how organizations choose their partners according to their geographical, cognitive, organizational, institutional and social proximity. Relational databases are constructed from resea

  12. Analisis Isi SMS Iklan Layanan Telekomunikasi Operator Telkomsel, Indosat dan Xl berdasarkan Etika Pariwara Indonesia Periode 2013

    Directory of Open Access Journals (Sweden)

    Danang Trijayanto

    2014-09-01

    Full Text Available Perkembangan teknologi komunikasi merevolusi aktivitas pemasaran ke mobile marketing, salah satunya adalah dengan SMS advertising. Badan usaha yang cenderung menggunakan cara pemasaran tersebut adalah operator selular dengan iklan produk layanan telekomunikasinya. Permasalahannya adalah strategi pemasaran produk telekomunikasi yang cenderung banyak merugikan pelanggan karena ketidaksesuaian antara isi iklan dan produk yang diperoleh, yang dipengaruhi oleh kelengkapan dan kejelasan informasi produk. Salah satu aturan yang menjadi dasar dalam aktivitas SMS advertising adalah berdasarkan Etika Pariwara Indonesia.  Penelitian  ini   meneliti  bagaimanakah  Penerapan aturan tersebut terhadap isi SMS iklan produk telekomunikasi yang dikirimkan oleh provider selular GSM prabayar pada bulan Juli hingga Nopember 2013.  Hasil  Penelitian menunjukkan bahwa dalam mengiklankan produk telekomunikasi melalui SMS advertising, para operator selular belum menerapkan regulasi dan etika pemasaran dengan baik. Kekurangan informasi yang belum lengkap terdapat pada informasi syarat kontrak yang menjadi informasi dasar hak dan kewajiban yang harus dipenuhi oleh pelanggan.

  13. An approach to effective UHF (S/L band) data communications for satellite Personal Communication Service (PCS)

    Science.gov (United States)

    Hayase, Joshua Y.

    1995-01-01

    Reliable signaling information transfer is fundamental in supporting the needs of data communication PCS via LMS (Land Mobile Service) SSs (satellite systems). The needs of the system designer can be satisfied only through the collection of media information that can be brought to bear on the pertinent design issues. We at ISI hope to continue our dialogue with fading media experts to address the unique data communications needs of PCS via LMS SSs.

  14. Performance of TCP Vegas, Bic and Reno Congestion Control Algorithms on Iridium Satellite Constellations

    Directory of Open Access Journals (Sweden)

    M.Nirmala

    2012-11-01

    Full Text Available Satellite networking is different from wired or wireless networks. The behavior and the performance of TCP/IP in normal wireless network as well as in wired network are different from one another. The TCP/IP protocol was not designed to perform well over high-latency or noisy channels so its performance over satellite networks are totally different. Each satellite networks/constellations have different properties. The deployment height, motion, direction, link capacity – all differ from one satellite constellations to another. So, certainly the behavior of TCP/IP will considerably differ from one satellite constellations than another.The Performance of three different TCP Congestion algorithms, Vegas, Reno and Bic are taken for evaluation on the simulated satellite network Iridium and the performance of the three algorithms under the satellites constellation is measured using suitable metrics. It is observed that, irrespective of the high end to end delay, the behavior of TCP/IP under Satellite network is somewhat resembling a high latency wired network. TCP under satellite network is not like that of a mobile ADHOC network. The observation resulted that the overall performance of Vegas was good in Iridium constellations. These reasons should be explored for designing a better congestion control algorithm exclusively for Satellite Networks.

  15. Environmental influences on the Indo-Pacific octocoral Isis hippuris Linnaeus 1758 (Alcyonacea: Isididae): genetic fixation or phenotypic plasticity?

    Science.gov (United States)

    Rowley, Sonia J; Pochon, Xavier; Watling, Les

    2015-01-01

    As conspicuous modular components of benthic marine habitats, gorgonian (sea fan) octocorals have perplexed taxonomists for centuries through their shear diversity, particularly throughout the Indo-Pacific. Phenotypic incongruence within and between seemingly unitary lineages across contrasting environments can provide the raw material to investigate processes of disruptive selection. Two distinct phenotypes of the Isidid Isis hippurisLinnaeus, 1758 partition between differing reef environments: long-branched bushy colonies on degraded reefs, and short-branched multi/planar colonies on healthy reefs within the Wakatobi Marine National Park (WMNP), Indonesia. Multivariate analyses reveal phenotypic traits between morphotypes were likely integrated primarily at the colony level with increased polyp density and consistently smaller sclerite dimensions at the degraded site. Sediment load and turbidity, hence light availability, primarily influenced phenotypic differences between the two sites. This distinct morphological dissimilarity between the two sites is a reliable indicator of reef health; selection primarily acting on colony morphology, porosity through branching structure, as well as sclerite diversity and size. ITS2 sequence and predicted RNA secondary structure further revealed intraspecific variation between I. hippuris morphotypes relative to such environments (ΦST = 0.7683, P < 0.001). This evidence suggests-but does not confirm-that I. hippuris morphotypes within the WMNP are two separate species; however, to what extent and taxonomic assignment requires further investigation across its full geographic distribution. Incongruence between colonies present in the WMNP with tenuously described Isis alternatives (Isis reticulataNutting, 1910, Isis minorbrachyblastaZou, Huang & Wang, 1991), questions the validity of such assignments. Furthermore, phylogenetic analyses confirm early taxonomic suggestion that the characteristic jointed axis of the Isididae is in

  16. Environmental influences on the Indo–Pacific octocoral Isis hippuris Linnaeus 1758 (Alcyonacea: Isididae): genetic fixation or phenotypic plasticity?

    Science.gov (United States)

    Pochon, Xavier; Watling, Les

    2015-01-01

    As conspicuous modular components of benthic marine habitats, gorgonian (sea fan) octocorals have perplexed taxonomists for centuries through their shear diversity, particularly throughout the Indo–Pacific. Phenotypic incongruence within and between seemingly unitary lineages across contrasting environments can provide the raw material to investigate processes of disruptive selection. Two distinct phenotypes of the Isidid Isis hippuris Linnaeus, 1758 partition between differing reef environments: long-branched bushy colonies on degraded reefs, and short-branched multi/planar colonies on healthy reefs within the Wakatobi Marine National Park (WMNP), Indonesia. Multivariate analyses reveal phenotypic traits between morphotypes were likely integrated primarily at the colony level with increased polyp density and consistently smaller sclerite dimensions at the degraded site. Sediment load and turbidity, hence light availability, primarily influenced phenotypic differences between the two sites. This distinct morphological dissimilarity between the two sites is a reliable indicator of reef health; selection primarily acting on colony morphology, porosity through branching structure, as well as sclerite diversity and size. ITS2 sequence and predicted RNA secondary structure further revealed intraspecific variation between I. hippuris morphotypes relative to such environments (ΦST = 0.7683, P < 0.001). This evidence suggests—but does not confirm—that I. hippuris morphotypes within the WMNP are two separate species; however, to what extent and taxonomic assignment requires further investigation across its full geographic distribution. Incongruence between colonies present in the WMNP with tenuously described Isis alternatives (Isis reticulata Nutting, 1910, Isis minorbrachyblasta Zou, Huang & Wang, 1991), questions the validity of such assignments. Furthermore, phylogenetic analyses confirm early taxonomic suggestion that the characteristic jointed axis of the

  17. Environmental influences on the Indo–Pacific octocoral Isis hippuris Linnaeus 1758 (Alcyonacea: Isididae: genetic fixation or phenotypic plasticity?

    Directory of Open Access Journals (Sweden)

    Sonia J. Rowley

    2015-08-01

    Full Text Available As conspicuous modular components of benthic marine habitats, gorgonian (sea fan octocorals have perplexed taxonomists for centuries through their shear diversity, particularly throughout the Indo–Pacific. Phenotypic incongruence within and between seemingly unitary lineages across contrasting environments can provide the raw material to investigate processes of disruptive selection. Two distinct phenotypes of the Isidid Isis hippuris Linnaeus, 1758 partition between differing reef environments: long-branched bushy colonies on degraded reefs, and short-branched multi/planar colonies on healthy reefs within the Wakatobi Marine National Park (WMNP, Indonesia. Multivariate analyses reveal phenotypic traits between morphotypes were likely integrated primarily at the colony level with increased polyp density and consistently smaller sclerite dimensions at the degraded site. Sediment load and turbidity, hence light availability, primarily influenced phenotypic differences between the two sites. This distinct morphological dissimilarity between the two sites is a reliable indicator of reef health; selection primarily acting on colony morphology, porosity through branching structure, as well as sclerite diversity and size. ITS2 sequence and predicted RNA secondary structure further revealed intraspecific variation between I. hippuris morphotypes relative to such environments (ΦST = 0.7683, P < 0.001. This evidence suggests—but does not confirm—that I. hippuris morphotypes within the WMNP are two separate species; however, to what extent and taxonomic assignment requires further investigation across its full geographic distribution. Incongruence between colonies present in the WMNP with tenuously described Isis alternatives (Isis reticulata Nutting, 1910, Isis minorbrachyblasta Zou, Huang & Wang, 1991, questions the validity of such assignments. Furthermore, phylogenetic analyses confirm early taxonomic suggestion that the characteristic jointed

  18. The Battle for Popular Support: An Analysis of America’s Efforts in the Struggle Against ISIS

    Science.gov (United States)

    2016-05-01

    cognitive dissonance with how things have gone in Iraq, Afghanistan, and so many other countries in which my comrades and I have served. I am proud to...Sunnis and Shia in the region. To explore this question, this thesis uses a systems- theory model that analyzes insurgencies according to how actions...counterinsurgency efforts in Vietnam from 1964-1968 to determine the validity of the systems- theory model. It then explores ongoing operations against ISIS from

  19. Satellite-Based Sunshine Duration for Europe

    Directory of Open Access Journals (Sweden)

    Bodo Ahrens

    2013-06-01

    Full Text Available In this study, two different methods were applied to derive daily and monthly sunshine duration based on high-resolution satellite products provided by the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT Satellite Application Facility on Climate Monitoring using data from Meteosat Second Generation (MSG SEVIRI (Spinning Enhanced Visible and Infrared Imager. The satellite products were either hourly cloud type or hourly surface incoming direct radiation. The satellite sunshine duration estimates were not found to be significantly different using the native 15-minute temporal resolution of SEVIRI. The satellite-based sunshine duration products give additional spatial information over the European continent compared with equivalent in situ-based products. An evaluation of the satellite sunshine duration by product intercomparison and against station measurements was carried out to determine their accuracy. The satellite data were found to be within ±1 h/day compared to high-quality Baseline Surface Radiation Network or surface synoptic observations (SYNOP station measurements. The satellite-based products differ more over the oceans than over land, mainly because of the treatment of fractional clouds in the cloud type-based sunshine duration product. This paper presents the methods used to derive the satellite sunshine duration products and the performance of the different retrievals. The main benefits and disadvantages compared to station-based products are also discussed.

  20. The MICE Muon Beam on ISIS and the beam-line instrumentation of the Muon Ionization Cooling Experiment

    CERN Document Server

    Bogomilov, M.; Kolev, D.; Russinov, I.; Tsenov, R.; Vankova-Kirilova, G.; Wang, L.; Xu, F.Y.; Zheng, S.X.; Bertoni, R.; Bonesini, M.; Ferri, F.; Lucchini, G.; Mazza, R.; Paleari, F.; Strati, F.; Palladino, V.; Cecchet, G.; de Bari, A.; Capponi, M.; Cirillo, A.; Iaciofano, A.; Manfredini, A.; Parisi, M.; Orestano, D.; Pastore, F.; Tonazzo, A.; Tortora, L.; Mori, Y.; Kuno, Y.; Sakamoto, H.; Sato, A.; Yano, T.; Yoshida, M.; Ishimoto, S.; Suzuki, S.; Yoshimura, K.; Filthaut, F.; Garoby, R.; Gilardoni, S.; Gruber, P.; Hanke, K.; Haseroth, H.; Janot, P.; Lombardi, A.; Ramberger, S.; Vretenar, M.; Bene, P.; Blondel, A.; Cadoux, F.; Graulich, J.S.; Grichine, V.; Gschwendtner, E.; Masciocchi, F.; Sandstrom, R.; Verguilov, V.; Wisting, H.; Petitjean, C.; Seviour, R.; Alexander, J.; Charnley, G.; Collomb, N.; Griffiths, S.; Martlew, B.; Moss, A.; Mullacrane, I.; Oates, A.; Owens, P.; White, C.; York, S.; Adams, D.; Apsimon, R.; Barclay, P.; Baynham, D.E.; Bradshaw, T.W.; Courthold, M.; Drumm, P.; Edgecock, R.; Hayler, T.; Hills, M.; Ivaniouchenkov, Y.; Jones, A.; Lintern, A.; MacWaters, C.; Nelson, C.; Nichols, A.; Preece, R.; Ricciardi, S.; Rochford, J.H.; Rogers, C.; Spensley, W.; Tarrant, J.; Tilley, K.; Watson, S.; Wilson, A.; Forrest, D.; Soler, F.J.P.; Walaron, K.; Cooke, P.; Gamet, R.; Alekou, A.; Apollonio, M.; Barber, G.; Clark, D.; Clark, I.; Dobbs, A.; Dornan, P.; Fish, A.; Hare, R.; Greenwood, S.; Jamdagni, A.; Kasey, V.; Khaleeq, M.; Leaver, J.; Long, K.; McKigney, E.; Matsushita, T.; Pasternak, J.; Sashalmi, T.; Savidge, T.; Takahashi, M.; Blackmore, V.; Carlisle, T.; Cobb, J.H.; Lau, W.; Rayner, M.; Tunnell, C.D.; Witte, H.; Yang, S.; Booth, C.N.; Hodgson, P.; Howlett, L.; Nicholson, R.; Overton, E.; Robinson, M.; Smith, P.; Adey, D.; Back, J.; Boyd, S.; Harrison, P.; Ellis, M.; Kyberd, P.; Littlefield, M.; Nebrensky, J.J.; Bross, A.D.; Geer, S.; Neuffer, D.; Moretti, A.; Popovic, M.; Cummings, M.A.C.; Roberts, T.J.; DeMello, A.; Green, M.A.; Li, D.; Virostek, S.; Zisman, M.S.; Freemire, B.; Hanlet, P.; Huang, D.; Kafka, G.; Kaplan, D.M.; Snopok, P.; Torun, Y.; Blot, S.; Kim, Y.K.; Bravar, U.; Onel, Y.; Cline, D.; Fukui, Y.; Lee, K.; Yang, X.; Rimmer, R.A.; Cremaldi, L.M.; Gregoire, G.; Hart, T.L.; Sanders, D.A.; Summers, D.J.; Coney, L.; Fletcher, R.; Hanson, G.G.; Heidt, C.; Gallardo, J.; Kahn, S.; Kirk, H.; Palmer, R.B.

    2012-01-01

    The international Muon Ionization Cooling Experiment (MICE), which is under construction at the Rutherford Appleton Laboratory (RAL), will demonstrate the principle of ionization cooling as a technique for the reduction of the phase-space volume occupied by a muon beam. Ionization cooling channels are required for the Neutrino Factory and the Muon Collider. MICE will evaluate in detail the performance of a single lattice cell of the Feasibility Study 2 cooling channel. The MICE Muon Beam has been constructed at the ISIS synchrotron at RAL, and in MICE Step I, it has been characterized using the MICE beam-instrumentation system. In this paper, the MICE Muon Beam and beam-line instrumentation are described. The muon rate is presented as a function of the beam loss generated by the MICE target dipping into the ISIS proton beam. For a 1 V signal from the ISIS beam-loss monitors downstream of our target we obtain a 30 KHz muon rate, with a neglible pion contamination in the beam.