Science.gov

Sample records for non-differential global positioning

  1. The Global Positioning System

    USGS Publications Warehouse

    ,

    1999-01-01

    The Global Positioning System (GPS) is a constellation of navigation satellites called Navigation Satellite Timing And Ranging (NAVSTAR), maintained by the U.S. Department of Defense. Many outdoor enthusiasts recognize that a handheld GPS receiver can be an accurate tool for determining their location on the terrain. The GPS receiver helps determine locations on the Earth's surface by collecting signals from three or more satellites through a process called triangulation. Identifying a location on the Earth is more useful if you also know about the surrounding topographic conditions. Using a topographic map with the GPS receiver provides important information about features of the surrounding terrain and can help you plot an effective route from one location to another.

  2. Global Positioning Satellite Recorder

    1997-11-10

    The GPS Tracker is a device (automotive unit) that records position (latitude and longitude), date, and time autonomously with time. The data from the GPS Tracker can be used offline with a personal computer and map data base to plot the track of where a vehicle or other mobile battery powered object has been. The invention simplifies field operations for recording location autonomously by obviating the need to execute a set of detailed instructions priormore » to operation. The vehicle combines GPS technology and a cpu with custom software to accomplish the task.« less

  3. Navstar/Global Positioning System

    NASA Technical Reports Server (NTRS)

    Ananda, M.

    1982-01-01

    The Global Positioning System (GPS) was developed to provide highly precise position, velocity, and time information to users anywhere in the area of the Earth and at any time. The GPS, when fully operational, will consist of 18 satellites in six orbital planes. Any GPS user, by receiving and processing the radio signals from the satellite network can instantaneously determine navigation information to an accuracy of about 15 m in position and 0.1 m/s in velocity. The GPS is compared with other systems such as Loran-C, Omega, TACAN and Transit.

  4. The Mathematics of the Global Positioning System.

    ERIC Educational Resources Information Center

    Nord, Gail D.; Jabon, David; Nord, John

    1997-01-01

    Presents an activity that illustrates the application of mathematics to modern navigation and utilizes the Global Positioning System (GPS). GPS is a constellation of 24 satellites that enables receivers to compute their position anywhere on the earth with great accuracy. (DDR)

  5. Global Position and Position Taking: The Case of Australia

    ERIC Educational Resources Information Center

    Marginson, Simon

    2007-01-01

    From 1990 to 2003, Australia's share of the global market in cross-border degrees grew from 1% to 9%. Full fee-paying foreign students now constitute one quarter of enrolments, and education is Australia's third largest services export. Positioned as an Anglo-American system on the edge of Asia, Australia has differentiated itself from the United…

  6. Geodetic positioning using a global positioning system of satellites

    NASA Technical Reports Server (NTRS)

    Fell, P. J.

    1980-01-01

    Geodetic positioning using range, integrated Doppler, and interferometric observations from a constellation of twenty-four Global Positioning System satellites is analyzed. A summary of the proposals for geodetic positioning and baseline determination is given which includes a description of measurement techniques and comments on rank deficiency and error sources. An analysis of variance comparison of range, Doppler, and interferometric time delay to determine their relative geometric strength for baseline determination is included. An analytic examination to the effect of a priori constraints on positioning using simultaneous observations from two stations is presented. Dynamic point positioning and baseline determination using range and Doppler is examined in detail. Models for the error sources influencing dynamic positioning are developed. Included is a discussion of atomic clock stability, and range and Doppler observation error statistics based on random correlated atomic clock error are derived.

  7. Tests Of A Differential Global Positioning System

    NASA Technical Reports Server (NTRS)

    Edwards, F. G.; Hegary, D. M.; Turner, R. N.; Van Graas, F.; Sharma, S.

    1990-01-01

    Paper describes validation tests of global positioning system (GPS) for low-flying helicopters. Configured as differential GPS, in which components in both aircraft and ground station compute position errors relative to known location using satellite navigational data. Corrections computed from differences between computed and measured ranges to four satellites being tracked by receiver in both aircraft and ground systems. Tests conducted to determine whether equipment and computer programs of system operated correctly and consistently.

  8. Nondynamic Tracking Using The Global Positioning System

    NASA Technical Reports Server (NTRS)

    Yunck, T. P.; Wu, Sien-Chong

    1988-01-01

    Report describes technique for using Global Positioning System (GPS) to determine position of low Earth orbiter without need for dynamic models. Differential observing strategy requires GPS receiver on user vehicle and network of six ground receivers. Computationally efficient technique delivers decimeter accuracy on orbits down to lowest altitudes. New technique nondynamic long-arc strategy having potential for accuracy of best dynamic techniques while retaining much of computational simplicity of geometric techniques.

  9. Global Positioning System Instruction in Higher Education.

    ERIC Educational Resources Information Center

    Wikle, Thomas A.; And Others

    1996-01-01

    Provides an overview of satellite-based global positioning system (GPS) technology and includes some illustrations of how GPS is introduced in field-based exercises in the educational setting. Highlights forestry and geography classes, but also discusses archeology, geology, and wildlife science. Benefits include affordability, flexibility,…

  10. Shuttle Global Positioning (GPS) System design study

    NASA Technical Reports Server (NTRS)

    Nilsen, P.; Huth, G. K.

    1980-01-01

    Investigations of certain aspects and problems of the shuttle global positioning system GPS, are presented. Included are: test philosophy and test outline; development of a phase slope specification for the shuttle GPS antenna; an investigation of the shuttle jamming vulnerability; and an expression for the GPS signal to noise density ratio for the thermal protection system.

  11. Shuttle Global Positioning System (GPS) design study

    NASA Technical Reports Server (NTRS)

    Nilsen, P. W.

    1979-01-01

    The effects of oscillator noise on Shuttle Global Positioning System (GPS) receiver performance, GPS navigation system self-test, GPS ground transmitter design to augment shuttle navigation, the effect of ionospheric delay modelling on GPS receiver design, and GPS receiver tracking of Shuttle transient maneuvers were investigated.

  12. Global positioning system missile test range applications

    SciTech Connect

    Partridge, M.E.

    1986-06-01

    Using the Global Positioning System (GPS), a missile under test could transmit its own position, reducing radar tracking requirements while still providing three-dimensional position and velocity data with the required accuracy. This study investigated minimum package size requirements for GPS implementation on the SRAM II missile as part of the joint test assembly telemetry system. Reported GPS missile test range applications are reviewed. The two missile tracking system implementations considered are a complete GPS package onboard the missile and onboard frequency translator that retransmits the GPS satellite signals. Accuracy and operation of the two methods are compared. A functional description of the GPS is provided.

  13. Non-differentiable variational principles

    NASA Astrophysics Data System (ADS)

    Cresson, Jacky

    2005-07-01

    We develop a calculus of variations for functionals which are defined on a set of non-differentiable curves. We first extend the classical differential calculus in a quantum calculus, which allows us to define a complex operator, called the scale derivative, which is the non-differentiable analogue of the classical derivative. We then define the notion of extremals for our functionals and obtain a characterization in term of a generalized Euler-Lagrange equation. We finally prove that solutions of the Schrödinger equation can be obtained as extremals of a non-differentiable variational principle, leading to an extended Hamilton's principle of least action for quantum mechanics. We compare this approach with the scale relativity theory of Nottale, which assumes a fractal structure of space-time.Résumé (Principes variationnels non différentiable). Nous développons un calcul des variations pour des fonctionnelles définies sur un ensemble de courbes non différentiables. Pour cela, nous étendons le calcul différentiel classique, en calcul appelé calcul quantique, qui nous permet de définir un opérateur à valeur complexes, appelé dérivée d'échelle, qui est l'analogue non différentiable de la dérivée usuelle. On définit alors la notion d'extremale pour ces fonctionnelles pour lesquelles nous obtenons une caractérisation via une équation d'Euler-Lagrange généralisée. On prouve enfin que les solutions de l'équation de Schrödinger peuvent s'obtenir comme solution d'un problème variationnel non différentiable, étendant ainsi le principe de moindre action de Hamilton au cadre de la mécanique quantique. On discute enfin la connexion entre ce travail et la théorie de la relativité d'échelle développée par Nottale, et qui suppose une structure fractale de l'espace-temps.

  14. Global positioning system recorder and method

    DOEpatents

    Hayes, D.W.; Hofstetter, K.J.; Eakle, R.F. Jr.; Reeves, G.E.

    1998-12-22

    A global positioning system recorder (GPSR) is disclosed in which operational parameters and recorded positional data are stored on a transferable memory element. Through this transferrable memory element, the user of the GPSR need have no knowledge of GPSR devices other than that the memory element needs to be inserted into the memory element slot and the GPSR must be activated. The use of the data element also allows for minimal downtime of the GPSR and the ability to reprogram the GPSR and download data therefrom, without having to physically attach it to another computer. 4 figs.

  15. Method and apparatus for determining position using global positioning satellites

    NASA Technical Reports Server (NTRS)

    Ward, John (Inventor); Ward, William S. (Inventor)

    1998-01-01

    A global positioning satellite receiver having an antenna for receiving a L1 signal from a satellite. The L1 signal is processed by a preamplifier stage including a band pass filter and a low noise amplifier and output as a radio frequency (RF) signal. A mixer receives and de-spreads the RF signal in response to a pseudo-random noise code, i.e., Gold code, generated by an internal pseudo-random noise code generator. A microprocessor enters a code tracking loop, such that during the code tracking loop, it addresses the pseudo-random code generator to cause the pseudo-random code generator to sequentially output pseudo-random codes corresponding to satellite codes used to spread the L1 signal, until correlation occurs. When an output of the mixer is indicative of the occurrence of correlation between the RF signal and the generated pseudo-random codes, the microprocessor enters an operational state which slows the receiver code sequence to stay locked with the satellite code sequence. The output of the mixer is provided to a detector which, in turn, controls certain routines of the microprocessor. The microprocessor will output pseudo range information according to an interrupt routine in response detection of correlation. The pseudo range information is to be telemetered to a ground station which determines the position of the global positioning satellite receiver.

  16. Method and Apparatus for Determining Position Using Global Positioning Satellites

    NASA Technical Reports Server (NTRS)

    Ward, John L. (Inventor)

    2001-01-01

    A global positioning satellite receiver having an antenna for receiving a L1 signal from a satellite is presented. The L1 signal is processed by a preamplifier stage including a band pass filter and a low noise amplifier and output as a radio frequency (RF) signal. A mixer receives and de-spreads the RF signal in response to a pseudo-random noise code, i,e., Gold code, generated by an internal pseudo-random noise code generator. A microprocessor enters a code tracking loop, such that during the code tracking loop, it addresses the pseudorandom code generator to cause the pseudo-random code generator to sequentially output pseudo-random codes corresponding to satellite codes used to spread the L1 signal, until correlation occurs. When an output of the mixer is indicative of the occurrence of correlation between the RF signal and the generated pseudo-random codes, the microprocessor caters an operational state which slows the receiver code sequence to stay locked with the satellite cede sequence. The output of the mixer is provided to a detector which, in turn, controls certain routines of the microprocessor. The microprocessor will output pseudo range information according to an interrupt routine in response detection of correlation. The pseudo range information is to be telemetered to a ground station which determines the position of the global positioning satellite receiver.

  17. Precise Applications Of The Global Positioning System

    NASA Technical Reports Server (NTRS)

    Lichten, Stephen M.

    1992-01-01

    Report represents overview of Global Positioning System (GPS). Emphasizes those aspects of theory, history, and status of GPS pertaining to potential utility for highly precise scientific measurements. Current and anticipated applications include measurements of crustal motions in seismically active regions of Earth, measurements of rate of rotation of Earth and orientation of poles, tracking of non-GPS spacecraft in orbit around Earth, surveying, measurements of radio-signal-propagation delays, determinations of coordinates of ground stations, and transfer of precise time signals worldwide.

  18. Global positioning system recorder: Software user guide

    SciTech Connect

    Toole, B.

    1996-02-12

    This manual provides information needed to use the Global Positioning System Recorder Data processing software. The software runs on an IBM compatible computer. The DeLorme XMp program requires Microsoft Windows and a CDROM reader. Section 5.1 `Copy GPSR data from PCMCIA card` and Section 5.4 `PCMCIA card setup for field use` require a PCMCIA drive installed in the computer. The user interfaces with the software using a computer keyboard and when in Windows, a mouse. New users can be trained by anyone with experience using the system.

  19. Global Positioning System receiver evaluation results

    SciTech Connect

    Byrne, R.H.

    1993-09-01

    A Sandia project currently uses an outdated Magnavox 6400 Global Positioning System (GPS) receiver as the core of its navigation system. The goal of this study was to analyze the performance of the current GPS receiver compared to newer, less expensive models and to make recommendations on how to improve the performance of the overall navigation system. This paper discusses the test methodology used to experimentally analyze the performance of different GPS receivers, the test results, and recommendations on how an upgrade should proceed. Appendices contain detailed information regarding the raw data, test hardware, and test software.

  20. Global positioning system supported pilot's display

    NASA Technical Reports Server (NTRS)

    Scott, Marshall M., Jr.; Erdogan, Temel; Schwalb, Andrew P.; Curley, Charles H.

    1991-01-01

    The hardware, software, and operation of the Microwave Scanning Beam Landing System (MSBLS) Flight Inspection System Pilot's Display is discussed. The Pilot's Display is used in conjunction with flight inspection tests that certify the Microwave Scanning Beam Landing System used at Space Shuttle landing facilities throughout the world. The Pilot's Display was developed for the pilot of test aircraft to set up and fly a given test flight path determined by the flight inspection test engineers. This display also aids the aircraft pilot when hazy or cloud cover conditions exist that limit the pilot's visibility of the Shuttle runway during the flight inspection. The aircraft position is calculated using the Global Positioning System and displayed in the cockpit on a graphical display.

  1. Single-satellite global positioning system

    NASA Astrophysics Data System (ADS)

    Bagrov, Alexander V.; Leonov, Vladislav A.; Mitkin, Alexander S.; Nasyrov, Alexander F.; Ponomarenko, Andreu D.; Pichkhadze, Konstantin M.; Sysoev, Valentin K.

    2015-12-01

    A new concept of a global positioning support system, based on only one satellite, was offered. Unlike all other GPS and GLONASS satellite systems that are in use, within the offered modification, all metrological support is provided by on-board measurements, which means, that it does not need any ground support of coordinate measurements or orbital characteristics of the satellite system. The cosmic-based angle-measuring instrument measures the arcs lengths between the measured ground-points, that are marked with light beacons, and navigation stars. Each measurement takes approximately 0.04 s, with the precision of 1 mm in recalculation to ground-relations. Long series of arc measurements between different objects on the ground and in the sky enable the solution of both determination of geodesic coordinates of the measured points and position of the spacecraft during the measuring process by using geodesic equation methods. In addition, it enables the qualification of the geopotential guaranties. The offered scheme will be used for the determination of the frame of selenocentric coordinates during the "Luna-Globe" and "Luna-Resource" missions for precise navigation of landing modules and maybe will be used for precise gridding of the Martian surface.

  2. Global Positioning System Satellite Selection Method

    NASA Technical Reports Server (NTRS)

    Niles, Frederick A. (Inventor)

    2001-01-01

    The satellite selection method as utilized by the spaceborne Global Positioning System receiver provides navigational solutions and is designed for use in low Earth orbit. The satellite selection method is a robust algorithm that can be used a GPS receiver to select appropriate GPS satellites for use in calculating point solutions or attitude solutions. The method is takes into account the difficulty of finding a particular GPS satellite phase code, especially when the search range in greatly increased due to Doppler shifts introduced into the carrier frequency. The method starts with an update of the antenna pointing and spacecraft vectors to determine the antenna backplane direction. Next, the GPS satellites that will potentially be in view of the antenna are ranked on a list, whereby the list is generated based on the estimated attitude and position of each GPS satellite. Satellites blocked by the Earth are not entered on this list. A second list is created, whereby the GPS satellites are ranked according to their desirability for use in attitude determination. GPS satellites are ranked according to their orthogonality to the antenna backplane, and according to geometric dilution of precision considerations. After the lists are created, the channels of the spaceborne GPS receiver are assigned to various GPS satellites for acquisition and lock. Preliminary Doppler frequencies for searching are assigned to the various channels.

  3. Spaceborne Global Positioning System for Spacecraft

    NASA Technical Reports Server (NTRS)

    Dougherty, Lamar F. (Inventor); Niles, Frederick A. (Inventor); Wennersten, Miriam D. (Inventor)

    2001-01-01

    The spaceborne Global Positioning System receiver provides navigational solutions and is designed for use in low Earth orbit. The spaceborne GPS receiver can determine the orbital position of a spacecraft using any of the satellites wi thin the GPS constellation. It is a multiple processor system incorporating redundancy by using a microcontroller to handle the closure of tracking loops for acquired GPS satellites, while a separate microprocessor computes the spacecraft navigational solution and handles other tasks within the receiver. 'Me spaceborne GPS receiver can use either microcontroller or the microprocessor to close the satellite tracking loops. The use of microcontroller provides better tracking performance of acquired GPS satellites. The spaceborne GPS receiver utilizes up to seven separate GPS boards, with each board including its own set of correlators, down-converters and front-end components. The spaceborne GPS receiver also includes telemetry and time-marking circuitry. The spaceborne GPS receiver communicates with other spacecraft systems through a variety of interfaces and can be software-configured to support several different mission profiles.

  4. Global Positioning System Simulator Field Operational Procedures

    NASA Technical Reports Server (NTRS)

    Kizhner, Semion; Quinn, David A.; Day, John H. (Technical Monitor)

    2002-01-01

    Global Positioning System (GPS) simulation is an important activity in the development or qualification of GPS signal receivers for space flight. Because a GPS simulator is a critical resource it is highly desirable to develop a set of field operational procedures to supplement the basic procedures provided by most simulator vendors. Validated field procedures allow better utilization of the GPS simulator in the development of new test scenarios and simulation operations. These procedures expedite simulation scenario development while resulting in scenarios that are more representative of the true design, as well as enabling construction of more complex simulations than previously possible, for example, spacecraft maneuvers. One difficulty in the development of a simulation scenario is specifying various modes of test vehicle motion and associated maneuvers requiring that a user specify some (but not all) of a few closely related simulation parameters. Currently this can only be done by trial and error. A stand-alone procedure that implements the simulator maneuver motion equations and solves for the motion profile transient times, jerk and acceleration would be of considerable value. Another procedure would permit the specification of some configuration parameters that would determine the simulated GPS signal composition. The resulting signal navigation message, for example, would force the receiver under test to use only the intended C-code component of the simulated GPS signal. A representative class of GPS simulation-related field operational procedures is described in this paper. These procedures were developed and used in support of GPS integration and testing for many successful spacecraft missions such as SAC-A, EO-1, AMSAT, VCL, SeaStar, sounding rockets, and by using the industry standard Spirent Global Simulation Systems Incorporated (GSSI) STR series simulators.

  5. Global Plate Velocities from the Global Positioning System

    NASA Technical Reports Server (NTRS)

    Larson, Kristine M.; Freymueller, Jeffrey T.; Philipsen, Steven

    1997-01-01

    We have analyzed 204 days of Global Positioning System (GPS) data from the global GPS network spanning January 1991 through March 1996. On the basis of these GPS coordinate solutions, we have estimated velocities for 38 sites, mostly located on the interiors of the Africa, Antarctica, Australia, Eurasia, Nazca, North America, Pacific, and South America plates. The uncertainties of the horizontal velocity components range from 1.2 to 5.0 mm/yr. With the exception of sites on the Pacific and Nazca plates, the GPS velocities agree with absolute plate model predictions within 95% confidence. For most of the sites in North America, Antarctica, and Eurasia, the agreement is better than 2 mm/yr. We find no persuasive evidence for significant vertical motions (less than 3 standard deviations), except at four sites. Three of these four were sites constrained to geodetic reference frame velocities. The GPS velocities were then used to estimate angular velocities for eight tectonic plates. Absolute angular velocities derived from the GPS data agree with the no net rotation (NNR) NUVEL-1A model within 95% confidence except for the Pacific plate. Our pole of rotation for the Pacific plate lies 11.5 deg west of the NNR NUVEL-1A pole, with an angular speed 10% faster. Our relative angular velocities agree with NUVEL-1A except for some involving the Pacific plate. While our Pacific-North America angular velocity differs significantly from NUVEL-1A, our model and NUVEL-1A predict very small differences in relative motion along the Pacific-North America plate boundary itself. Our Pacific-Australia and Pacific- Eurasia angular velocities are significantly faster than NUVEL-1A, predicting more rapid convergence at these two plate boundaries. Along the East Pacific Pise, our Pacific-Nazca angular velocity agrees in both rate and azimuth with NUVFL-1A.

  6. Geophysical applications of the global positioning system

    NASA Astrophysics Data System (ADS)

    Mao, Ailin

    1998-12-01

    Observation of land surface motions plays a critical role in the study of a wide range of geophysical phenomena. The Global Positioning System (GPS), designed by the US Department of Defense for military and civilian navigation and positioning, has been used to measure crustal motion. The ever expanding global network of GPS sites improves both temporal and spatial resolution of geophysical phenomena. I assess the noise characteristics in time series of daily position estimates for 23 GPS stations with three years of data, using spectral analysis and Maximum Likelihood Estimation. A combination of white plus flicker noise can be used to model the noise characteristics of all three position components. Both white and flicker noise amplitudes are smallest in the north component and largest in the vertical component. The white noise part of the vertical component is higher for tropical stations (±23sp° latitude) compared to mid-latitude stations, which may be related to high wet tropospheric path delay and/or higher variability. Velocity error in the coordinate time series may be underestimated by factors of 5-11 if a pure white noise model is assumed. I analyze data from 20 permanent GPS stations broadly distributed through the interior of the North American plate, and use the resulting velocities to estimate an Euler vector describing motion of "stable" North America as a single rigid plate. The site velocities fit the single plate model with a mean residual of 1.3 mm/yr. The residuals do not appear to reflect post-glacial rebound, and tests for differential motion between eastern and western North America at the New Madrid seismic zone show no resolvable motion within uncertainties. The residuals more likely reflect observational error, and thus our estimate of the stability of the plate interior is likely an upper bound. In addition, I found that GPS velocity errors estimated with the white plus flicker noise model fit the observations significantly better than

  7. Connect Global Positioning System RF Module

    NASA Technical Reports Server (NTRS)

    Franklin, Garth W.; Young, Lawrence E.; Ciminera, Michael A.; Tien, Jeffrey Y.; Gorelik, Jacob; Okihiro, Brian Bachman; Koelewyn, Cynthia L.

    2012-01-01

    The CoNNeCT Global Positioning System RF Module (GPSM) slice is part of the JPL CoNNeCT Software Defined Radio (SDR). CoNNeCT is the Communications, Navigation, and Net working reconfigurable Testbed project that is part of NASA's Space Communication and Nav igation (SCaN) Program. The CoNNeCT project is an experimental dem onstration that will lead to the advancement of SDRs and provide a path for new space communication and navigation systems for future NASA exploration missions. The JPL CoNNeCT SDR will be flying on the International Space Station (ISS) in 2012 in support of the SCaN CoNNeCT program. The GPSM is a radio-frequency sampler module (see Figure 1) that directly sub-harmonically samples the filtered GPS L-band signals at L1 (1575.42 MHz), L2 (1227.6 MHz), and L5 (1176.45 MHz). The JPL SDR receives GPS signals through a Dorne & Margolin antenna mounted onto a choke ring. The GPS signal is filtered against interference, amplified, split, and fed into three channels: L1, L2, and L5. In each of the L-band channels, there is a chain of bandpass filters and amplifiers, and the signal is fed through each of these channels to where the GPSM performs a one-bit analog-to-digital conversion (see Figure 2). The GPSM uses a sub-harmonic, single-bit L1, L2, and L5 sampler that samples at a clock rate of 38.656 MHz. The new capability is the down-conversion and sampling of the L5 signal when previous hardware did not provide this capability. The first GPS IIF Satellite was launched in 2010, providing the new L5 signal. With the JPL SDR flying on the ISS, it will be possible to demonstrate navigation solutions with 10-meter 3-D accuracy at 10-second intervals using a field-program mable gate array (FPGA)-based feedback loop running at 50 Hz. The GPS data bits will be decoded and used in the SDR. The GPSM will also allow other waveforms that are installed in the SDR to demonstrate various GNSS tracking techniques.

  8. Measuring Global Position Using the Sun

    ERIC Educational Resources Information Center

    Murphy, Evan; Hughes, Stephen

    2014-01-01

    The determination of latitude and longitude on Earth has always been of interest to explorers and cartographers alike. Accurate positional information is often needed for rescue purposes in locations where satellite navigational systems are inoperable. The activity described in this paper demonstrates a simple procedure to determine latitude and…

  9. Can global positioning systems quantify participation in cerebral palsy?

    PubMed

    Ben-Pazi, Hilla; Barzilay, Yair; Shoval, Noam

    2014-06-01

    This study examined whether motor-related participation could be assessed by global positioning systems in individuals with cerebral palsy. Global positioning systems monitoring devices were given to 2 adolescent girls (14-year-old with diplegic cerebral palsy and her 15-year-old healthy sister). Outcome measures were traveling distances, time spent outdoors, and Children's Assessment of Participation and Enjoyment questionnaires. Global positioning systems documented that the girl with cerebral palsy did not visit nearby friends, spent less time outdoors and traveled shorter distances than her sister (P = .02). Participation questionnaire corroborated that the girl with cerebral palsy performed most activities at home alone. Lower outdoor activity of the girl with cerebral palsy measured by a global positioning system was 29% to 53% of that of her sibling similar to participation questionnaires (44%). Global positioning devices objectively documented low outdoor activity in an adolescent with cerebral palsy compared to her sibling reflecting participation reported by validated questionnaires. Global positioning systems can potentially quantify certain aspects of participation.

  10. The effect of different Global Navigation Satellite System methods on positioning accuracy in elite alpine skiing.

    PubMed

    Gilgien, Matthias; Spörri, Jörg; Limpach, Philippe; Geiger, Alain; Müller, Erich

    2014-10-03

    In sport science, Global Navigation Satellite Systems (GNSS) are frequently applied to capture athletes' position, velocity and acceleration. Application of GNSS includes a large range of different GNSS technologies and methods. To date no study has comprehensively compared the different GNSS methods applied. Therefore, the aim of the current study was to investigate the effect of differential and non-differential solutions, different satellite systems and different GNSS signal frequencies on position accuracy. Twelve alpine ski racers were equipped with high-end GNSS devices while performing runs on a giant slalom course. The skiers' GNSS antenna positions were calculated in three satellite signal obstruction conditions using five different GNSS methods. The GNSS antenna positions were compared to a video-based photogrammetric reference system over one turn and against the most valid GNSS method over the entire run. Furthermore, the time for acquisitioning differential GNSS solutions was assessed for four differential methods. The only GNSS method that consistently yielded sub-decimetre position accuracy in typical alpine skiing conditions was a differential method using American (GPS) and Russian (GLONASS) satellite systems and the satellite signal frequencies L1 and L2. Under conditions of minimal satellite signal obstruction, valid results were also achieved when either the satellite system GLONASS or the frequency L2 was dropped from the best configuration. All other methods failed to fulfill the accuracy requirements needed to detect relevant differences in the kinematics of alpine skiers, even in conditions favorable for GNSS measurements. The methods with good positioning accuracy had also the shortest times to compute differential solutions. This paper highlights the importance to choose appropriate methods to meet the accuracy requirements for sport applications.

  11. The Effect of Different Global Navigation Satellite System Methods on Positioning Accuracy in Elite Alpine Skiing

    PubMed Central

    Gilgien, Matthias; Spörri, Jörg; Limpach, Philippe; Geiger, Alain; Müller, Erich

    2014-01-01

    In sport science, Global Navigation Satellite Systems (GNSS) are frequently applied to capture athletes' position, velocity and acceleration. Application of GNSS includes a large range of different GNSS technologies and methods. To date no study has comprehensively compared the different GNSS methods applied. Therefore, the aim of the current study was to investigate the effect of differential and non-differential solutions, different satellite systems and different GNSS signal frequencies on position accuracy. Twelve alpine ski racers were equipped with high-end GNSS devices while performing runs on a giant slalom course. The skiers' GNSS antenna positions were calculated in three satellite signal obstruction conditions using five different GNSS methods. The GNSS antenna positions were compared to a video-based photogrammetric reference system over one turn and against the most valid GNSS method over the entire run. Furthermore, the time for acquisitioning differential GNSS solutions was assessed for four differential methods. The only GNSS method that consistently yielded sub-decimetre position accuracy in typical alpine skiing conditions was a differential method using American (GPS) and Russian (GLONASS) satellite systems and the satellite signal frequencies L1 and L2. Under conditions of minimal satellite signal obstruction, valid results were also achieved when either the satellite system GLONASS or the frequency L2 was dropped from the best configuration. All other methods failed to fulfill the accuracy requirements needed to detect relevant differences in the kinematics of alpine skiers, even in conditions favorable for GNSS measurements. The methods with good positioning accuracy had also the shortest times to compute differential solutions. This paper highlights the importance to choose appropriate methods to meet the accuracy requirements for sport applications. PMID:25285461

  12. The Ether Wind and the Global Positioning System.

    ERIC Educational Resources Information Center

    Muller, Rainer

    2000-01-01

    Explains how students can perform a refutation of the ether theory using information from the Global Positioning System (GPS). Discusses the functioning of the GPS, qualitatively describes how position determination would be affected by an ether wind, and illustrates the pertinent ideas with a simple quantitative model. (WRM)

  13. Global positioning system applications at the Bonneville Power Administration

    SciTech Connect

    Street, M.A.; Thurein, I.P.; Martin, K.E.

    1995-12-31

    The Bonneville Power Administration (BPA) has used the precise timing feature of the Global Positioning System (GPS) to enhance power system performance and reliability. The BPA Traveling Wave Fault Locator System and the BPA Phasor Measurement System both employ GPS timing.

  14. Finding a Target with an Accessible Global Positioning System

    ERIC Educational Resources Information Center

    Ponchillia, Paul E.; MacKenzie, Nancy; Long, Richard G.; Denton-Smith, Pamela; Hicks, Thomas L.; Miley, Priscilla

    2007-01-01

    This article presents two target-location experiments. In the first experiment, 19 participants located a 25-foot chalk circle 93% of the time with a Global Positioning System (GPS) compared to 12% of the time without it. In a single-subject follow-up experiment, the participant came within 1 foot of the target on all GPS trials. Target-location…

  15. 78 FR 22554 - Nationwide Differential Global Positioning System (NDGPS)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-16

    ... records notice regarding our public dockets in the January 17, 2008 issue of the Federal Register (73 FR... needs and systems requirements of the inland (terrestrial) component of the NDGPS (72 FR 42219). On... Nationwide Differential Global Positioning System (NDGPS) AGENCY: Coast Guard, DHS and Research...

  16. Navstar Global Positioning System (GPS) clock program: Present and future

    NASA Technical Reports Server (NTRS)

    Tennant, D. M.

    1981-01-01

    Global Positioning System (GPS) program status are discussed and plans for ensuring the long term continuation of the program are presented. Performance of GPS clocks is presented in terms of on orbit data as portrayed by GPS master control station kalman filter processing. The GPS Clock reliability program is reviewed in depth and future plans fo the overall clock program are published.

  17. Global Positioning Systems: Keeping Us on Track. Resources in Technology.

    ERIC Educational Resources Information Center

    Valesey, Brigitte G.

    1998-01-01

    The Global Positioning System is a satellite-based system used to determine location, speed, and precise time in any weather, anywhere on earth. Developed by the U.S. Air Force as a defense system, it is now available for civilian and commercial uses. (JOW)

  18. The Evolution of Global Positioning System (GPS) Technology.

    ERIC Educational Resources Information Center

    Kumar, Sameer; Moore, Kevin B.

    2002-01-01

    Describes technological advances in the Global Positioning System (GPS), which is also known as the NAVSTAR GPS satellite constellation program developed in 1937, and changes in the nature of our world by GPS in the areas of agriculture, health, military, transportation, environment, wildlife biology, surveying and mapping, space applications, and…

  19. High precision applications of the global positioning system

    NASA Technical Reports Server (NTRS)

    Lichten, Stephen M.

    1991-01-01

    The Global Positioning System (GPS) is a constellation of U.S. defense navigation satellites which can be used for military and civilian positioning applications. A wide variety of GPS scientific applications were identified and precise positioning capabilities with GPS were already demonstrated with data available from the present partial satellite constellation. Expected applications include: measurements of Earth crustal motion, particularly in seismically active regions; measurements of the Earth's rotation rate and pole orientation; high-precision Earth orbiter tracking; surveying; measurements of media propagation delays for calibration of deep space radiometric data in support of NASA planetary missions; determination of precise ground station coordinates; and precise time transfer worldwide.

  20. Sub-milliarcsecond determination of pole position using Global Positioning System data

    NASA Technical Reports Server (NTRS)

    Herring, Thomas A.; Dong, Danan; King, Robert W.

    1991-01-01

    The determination of pole-position variations from the analysis of 23 days of Global Positioning System (GPS) data continuously collected with a globally distributed, 21-station network is discussed. The comparison of the estimated pole positions from these data with results from 11 very long baseline interferometry (VLBI) experiments conducted during this same interval yields weighted root-mean-square differences about the mean differences of 0.5 mas for both X- and Y-pole position estimates from an analysis using single-day arcs, and 1.0 and 0.8 mas from an analysis using three weekly multiday arcs. These results are of sufficient quality that GPS could provide an alternative technique to VLBI and satellite laser ranging for regular monitoring of high-time-resolution variations in the position of the earth's rotation axis.

  1. International GPS (Global Positioning System) Service for Geodynamics

    NASA Technical Reports Server (NTRS)

    Zumberge, J. F. (Editor); Liu, R. (Editor); Neilan, R. E. (Editor)

    1995-01-01

    The International GPS (Global Positioning System) Service for Geodynamics (IGS) began formal operation on January 1, 1994. This first annual report is divided into sections, which mirror different aspects of the service. Section (1) contains general information, including the history of the IGS, its organization, and the global network of GPS tracking sites; (2) contains information on the Central Bureau Information System; (3) describes the International Earth Rotation Service (IERS); (4) details collecting and distributing IGS data in Data Center reports; (6) describes how the IGS Analysis Centers generate their products; (7) contains miscellaneous contributions from other organizations that share common interests with the IGS.

  2. Impacts of GNSS position offsets on global frame stability

    NASA Astrophysics Data System (ADS)

    Griffiths, Jake; Ray, Jim

    2014-05-01

    Positional offsets appear in Global Navigation Satellite System (GNSS) time series for a variety of reasons. Antenna or radome changes are the most common cause for these discontinuities. Many others are from earthquakes, receiver changes, and different anthropogenic modifications at or near the stations. Some jumps appear for unknown or undocumented reasons. The accurate determination of station velocities, and therefore geophysical parameters and terrestrial reference frames, requires that positional offsets be correctly found and compensated. Williams (2003) found that undetected offsets introduce a random walk error component in individual station time series. The topic of detecting positional offsets has received considerable attention in recent years (e.g., Detection of Offsets in GPS Experiment; DOGEx), and most research groups using GNSS have adopted a combination of manual and automated methods for finding them. The removal of a positional offset is usually handled by estimating the average station position on both sides of the discontinuity, assuming a constant, continuous velocity. This is sufficient in the absence of time-correlated errors. However, GNSS time series contain systematic and power-law errors (white to random walk noise). In this paper, we aim to evaluate the impact to both individual station results and the overall stability of the global reference frame from adding increasing numbers of positional discontinuities. We use the International GNSS Service (IGS) weekly SINEX files, and iteratively insert positional offset parameters at the midpoint of each data segment. Each iteration includes a restacking of the modified SINEX files using the CATREF software from Institut National de l'Information Géographique et Forestière (IGN) to estimate: regularized station positions, secular velocities, Earth orientation parameters, Helmert frame alignment parameters, and the empirical shifts across all positional discontinuities. A comparison of the

  3. Global positioning system recorder and method government rights

    DOEpatents

    Hayes, David W.; Hofstetter, Kenneth J.; Eakle, Jr., Robert F.; Reeves, George E.

    1998-01-01

    A global positioning system recorder (GPSR) is disclosed in which operational parameters and recorded positional data are stored on a transferable memory element. Through this transferrable memory element, the user of the GPSR need have no knowledge of GPSR devices other than that the memory element needs to be inserted into the memory element slot and the GPSR must be activated. The use of the data element also allows for minimal downtime of the GPSR and the ability to reprogram the GPSR and download data therefrom, without having to physically attach it to another computer.

  4. NAVSTAR Global Positioning System. (Latest citations from the Aerospace Database)

    NASA Technical Reports Server (NTRS)

    1996-01-01

    The bibliography contains citations concerning the global system of navigation satellites developed to provide immediate and accurate worldwide three-dimensional positioning by air, land, and sea vehicles equipped with appropriate receiving equipment. Technological forecasting, reliability, performance tests, and evaluations are discussed. Developments and applications of the NAVSTAR system are included. (Contains 50-250 citations and includes a subject term index and title list.)

  5. Helicopter precision approach capability using the Global Positioning System

    NASA Technical Reports Server (NTRS)

    Kaufmann, David N.

    1992-01-01

    The period between 1 July and 31 December, 1992, was spent developing a research plan as well as a navigation system document and flight test plan to investigate helicopter precision approach capability using the Global Positioning System (GPS). In addition, all hardware and software required for the research was acquired, developed, installed, and verified on both the test aircraft and the ground-based reference station.

  6. Spacecraft applications of advanced global positioning system technology

    NASA Technical Reports Server (NTRS)

    Huth, Gaylord; Dodds, James; Udalov, Sergei; Austin, Richard; Loomis, Peter; Duboraw, I. Newton, III

    1988-01-01

    The purpose of this study was to evaluate potential uses of Global Positioning System (GPS) in spacecraft applications in the following areas: attitude control and tracking; structural control; traffic control; and time base definition (synchronization). Each of these functions are addressed. Also addressed are the hardware related issues concerning the application of GPS technology and comparisons are provided with alternative instrumentation methods for specific functions required for an advanced low earth orbit spacecraft.

  7. NAVSTAR Global Positioning System. (Latest citations from the Aerospace Database)

    NASA Technical Reports Server (NTRS)

    1998-01-01

    The bibliography contains citations concerning the global system of navigation satellites developed to provide immediate and accurate worldwide three-dimensional positioning by air, land, and sea vehicles equipped with appropriate receiving equipment. Technological forecasting, reliability, performance tests, and evaluations are discussed. Developments and applications of the NAVSTAR system are included.(Contains 50-250 citations and includes a subject term index and title list.)

  8. An analysis of GDOP in global positioning system navigation

    NASA Technical Reports Server (NTRS)

    Fang, B. T.

    1980-01-01

    The accuracy of user navigation fix based on the NAVSTAR global positioning system is described. The trace of this matrix serves as a convenient navigation performance index and the square root of the trace is called geometric dilution of precision (GDOP). Certain theoretical results concerning the general properties of the navigation performance are derived. An efficient algorithm for the computation of GDOP is given. Applications of the results are illustrated by numerical examples.

  9. Global Positioning System test of the local position invariance of Planck's constant.

    PubMed

    Kentosh, J; Mohageg, M

    2012-03-16

    Publicly available clock correction data from the Global Positioning System was analyzed and used in combination with the results of terrestrial clock comparison experiments to confirm the local position invariance (LPI) of Planck's constant within the context of general relativity. The results indicate that h is invariant within a limit of |β(h)|<0.007, where β(h) is a dimensionless parameter that represents the extent of LPI violation.

  10. High accuracy autonomous navigation using the global positioning system (GPS)

    NASA Technical Reports Server (NTRS)

    Truong, Son H.; Hart, Roger C.; Shoan, Wendy C.; Wood, Terri; Long, Anne C.; Oza, Dipak H.; Lee, Taesul

    1997-01-01

    The application of global positioning system (GPS) technology to the improvement of the accuracy and economy of spacecraft navigation, is reported. High-accuracy autonomous navigation algorithms are currently being qualified in conjunction with the GPS attitude determination flyer (GADFLY) experiment for the small satellite technology initiative Lewis spacecraft. Preflight performance assessments indicated that these algorithms are able to provide a real time total position accuracy of better than 10 m and a velocity accuracy of better than 0.01 m/s, with selective availability at typical levels. It is expected that the position accuracy will be increased to 2 m if corrections are provided by the GPS wide area augmentation system.

  11. Impacts of GNSS position offsets on global frame stability

    NASA Astrophysics Data System (ADS)

    Griffiths, Jake; Ray, Jim

    2015-04-01

    Positional offsets appear in Global Navigation Satellite System (GNSS) time series for a variety of reasons. Antenna or radome changes are the most common cause for these discontinuities. Many others are from earthquakes, receiver changes, and different anthropogenic modifications at or near the stations. Some jumps appear for unknown or undocumented reasons. Accurate determination of station velocities, and therefore geophysical parameters and terrestrial reference frames, requires that positional offsets be correctly found and compensated. Williams (2003) found that undetected offsets introduce a random walk error component in individual station time series. The topic of detecting positional offsets has received considerable attention in recent years (e.g., Detection of Offsets in GPS Experiment; DOGEx), and most research groups using GNSS have adopted a mix of manual and automated methods for finding them. The removal of a positional offset from a time series is usually handled by estimating the average station position on both sides of the discontinuity. Except for large earthquake events, the velocity is usually assumed constant and continuous across the positional jump. This approach is sufficient in the absence of time-correlated errors. However, GNSS time series contain periodic and power-law (flicker) errors. In this paper, we evaluate the impact to individual station results and the overall stability of the global reference frame from adding increasing numbers of positional discontinuities. We use the International GNSS Service (IGS) weekly SINEX files, and iteratively insert positional offset parameters. Each iteration includes a restacking of the modified SINEX files using the CATREF software from Institut National de l'Information Géographique et Forestière (IGN). Comparisons of successive stacked solutions are used to assess the impacts on the time series of x-pole and y-pole offsets, along with changes in regularized position and secular velocity

  12. Measuring earth orientation with the Global Positioning System

    NASA Technical Reports Server (NTRS)

    Freedman, Adam P.

    1991-01-01

    A globally distributed network of high-precision receivers which obtain data from the full Global Positioning System (GPS) configuration of 18 or more satellites may soon become an efficient and economical method for the rapid determination of short-term variations in earth orientation. A covariance analysis has been performed to evaluate the errors associated with GPS monitoring of earth orientation. Earth orientation parameters were modeled either as constants over observing windows of various lengths, or as stochastic process-noise variables. The sensitivity of earth orientation estimates to systematic errors in selected model parameters was also examined. GPS measurements appear to be highly competitive with those from other techniques, and have the potential to generate nearly continuous centimeter-level earth orientation information to aid both spacecraft navigation and the study of high-frequency earth orientation-related processes.

  13. Determination of Earth orientation using the Global Positioning System

    NASA Technical Reports Server (NTRS)

    Freedman, A. P.

    1989-01-01

    Modern spacecraft tracking and navigation require highly accurate Earth-orientation parameters. For near-real-time applications, errors in these quantities and their extrapolated values are a significant error source. A globally distributed network of high-precision receivers observing the full Global Positioning System (GPS) configuration of 18 or more satellites may be an efficient and economical method for the rapid determination of short-term variations in Earth orientation. A covariance analysis using the JPL Orbit Analysis and Simulation Software (OASIS) was performed to evaluate the errors associated with GPS measurements of Earth orientation. These GPS measurements appear to be highly competitive with those from other techniques and can potentially yield frequent and reliable centimeter-level Earth-orientation information while simultaneously allowing the oversubscribed Deep Space Network (DSN) antennas to be used more for direct project support.

  14. Atmospheric pressure loading effects on Global Positioning System coordinate determinations

    NASA Technical Reports Server (NTRS)

    Vandam, Tonie M.; Blewitt, Geoffrey; Heflin, Michael B.

    1994-01-01

    Earth deformation signals caused by atmospheric pressure loading are detected in vertical position estimates at Global Positioning System (GPS) stations. Surface displacements due to changes in atmospheric pressure account for up to 24% of the total variance in the GPS height estimates. The detected loading signals are larger at higher latitudes where pressure variations are greatest; the largest effect is observed at Fairbanks, Alaska (latitude 65 deg), with a signal root mean square (RMS) of 5 mm. Out of 19 continuously operating GPS sites (with a mean of 281 daily solutions per site), 18 show a positive correlation between the GPS vertical estimates and the modeled loading displacements. Accounting for loading reduces the variance of the vertical station positions on 12 of the 19 sites investigated. Removing the modeled pressure loading from GPS determinations of baseline length for baselines longer than 6000 km reduces the variance on 73 of the 117 baselines investigated. The slight increase in variance for some of the sites and baselines is consistent with expected statistical fluctuations. The results from most stations are consistent with approximately 65% of the modeled pressure load being found in the GPS vertical position measurements. Removing an annual signal from both the measured heights and the modeled load time series leaves this value unchanged. The source of the remaining discrepancy between the modeled and observed loading signal may be the result of (1) anisotropic effects in the Earth's loading response, (2) errors in GPS estimates of tropospheric delay, (3) errors in the surface pressure data, or (4) annual signals in the time series of loading and station heights. In addition, we find that using site dependent coefficients, determined by fitting local pressure to the modeled radial displacements, reduces the variance of the measured station heights as well as or better than using the global convolution sum.

  15. Virtual global positioning system for distributed interactive simulation environments

    NASA Astrophysics Data System (ADS)

    Williams, Gary; Stytz, Martin R.; Banks, Sheila B.

    1997-07-01

    A major shortfall in the fidelity of current military distributed virtual environments (DVEs) is the lack of virtual global positioning system (GPS) timing and position signals for entities within the environment. The DVE's usefulness is reduced because positional errors and positional accuracy that would be available in the real world are not present in the DVE. This, in turn, affects the validity of the results of training, analysis, and evaluations involving systems that rely on GPS. The magnitude of the affect depends on the degree that the systems involved in the DVE rely on GPS in the real world. The project reported in this paper addresses this deficit in current military DVEs. The capability we developed to provide a virtual GPS-based navigation capability within a DVE is based upon three components. These components are a complete virtual GPS satellite constellation, a means for broadcasting GPS signals using the Distributed Interactive Simulation (DIS) simulation protocols, and a software system, the Virtual GPS Receiver (VGPSR), to calculate simulation entity position using the virtual GPS time and position signals. The virtual GPS satellites are propagated in their orbits using the solar system modeler (SM). The SM also performs the simulated GPS signal broadcast by transmitting a DIS protocol data unit (PDU) with the data that would appear within a real world GPS satellite broadcast. The VGPSR is a plug-in module available for simulation applications that require virtual GPS navigation. To demonstrate the capability of this system, we used the VGPSR in conjunction with the virtual cockpit to simulate virtual weapons deployment. We present the design of the VGPSR and the design of the modules added to the SM for GPS broadcast. We describe the calculations the system performs to calculate position in the virtual environment and we describe the accuracy and performance the system achieves when calculating virtual environment position using our system. We

  16. Wide area augmentation of the Global Positioning System

    SciTech Connect

    Enge, P.; Walter, T.; Pullen, S.; Kee, C.; Chao, Y.C.; Tsai, Y.J.

    1996-08-01

    The Wide Area Augmentation System (WAAS) is being deployed by the Federal Aviation Administration (FAA) to augment the Global Positioning System (GPS). The WAAS will aid GPS with the following three services. First, it will broadcast spread-spectrum ranging signals from communication satellites. The airborne WAAS receiver will add these new ranging signals to the GPS constellation of measurements. By so doing, the augmented position fix will be less sensitive to the failure of individual system components, thus improving time availability and continuity of service. Second, the WAAS will use a nationwide ground network to monitor the health of all satellites over the airspace and flag situations which threaten flight safety. This data will be modulated on to the WAAS ranging signals and broadcast to the users, thereby guaranteeing the integrity of the airborne position fix. Third, the WAAS will use the ground network to develop corrections for the errors which currently limit the accuracy of unaugmented GPS. This data will also be included on the WAAS broadcast and will improve position accuracy from approximately 100 m to 8 m. When complete, the augmented system will provide an accurate position fix from satellites to an unlimited number of aircraft across the nation. It will be the primary navigation system for aircraft in oceanic routes, enroute over domestic airspace, in crowded metropolitan airspaces, and on airport approach.

  17. Multipath effects in a Global Positioning Satellite system receiver

    NASA Technical Reports Server (NTRS)

    Mcdonald, Malcolm W.

    1992-01-01

    This study, as a part of a large continuing investigation being conducted by the Communications Systems Branch of the Information and Electronic Systems Laboratory at the Marshall Space Flight Center, was undertaken to explore the multipath response characteristics of a particular Global Positioning Satellite (GPS) receiver which was available in the laboratory at the beginning and throughout the entirety of the study, and to develop a suitable regime of experimental procedure which can be applied to other state-of-the-art GPS receivers in the larger investigation.

  18. Autonomous satellite navigation with the Global Positioning System

    NASA Technical Reports Server (NTRS)

    Fuchs, A. J.; Wooden, W. H., II; Long, A. C.

    1977-01-01

    This paper discusses the potential of using the Global Positioning System (GPS) to provide autonomous navigation capability to NASA satellites in the 1980 era. Some of the driving forces motivating autonomous navigation are presented. These include such factors as advances in attitude control systems, onboard science annotation, and onboard gridding of imaging data. Simulation results which demonstrate baseline orbit determination accuracies using GPS data on Seasat, Landsat-D, and the Solar Maximum Mission are presented. Emphasis is placed on identifying error sources such as GPS time, GPS ephemeris, user timing biases, and user orbit dynamics, and in a parametric sense on evaluating their contribution to the orbit determination accuracies.

  19. A program status report on the Navstar Global Positioning System

    NASA Astrophysics Data System (ADS)

    Niiya, Craig; Lamons, John W.

    1992-03-01

    The USAF's GPS Joint Program Office is charged with the development, testing, and deployment of the space, control, and user segments of GPS, whose 24-satellite constellation will furnish global position, velocity, and time data to both military and civilian users after reaching operational status in the autumn of 1993. Responsibility for the operation and maintenance of the GPS constellation was transferred to USAF as of May, 1990. The GPS control segment is fully deployed at this writing; the user segment's equipment is in 'limited rate initial production', but will begin full-rate production in fiscal year 1993.

  20. Accurate aircraft wind measurements using the global positioning system (GPS)

    SciTech Connect

    Dobosy, R.J.; Crawford, T.L., McMillen, R.T., Dumas, E.J.

    1996-11-01

    High accuracy measurements of the spatial distribution of wind speed are required in the study of turbulent exchange between the atmosphere and the earth. The use of a differential global positioning system (GPS) to determine the sensor velocity vector component of wind speed is discussed in this paper. The results of noise and rocking testing are summarized, and fluxes obtained from the GPS-based methods are compared to those measured from systems on towers and airplanes. The GPS-based methods provided usable measurements that compared well with tower and aircraft data at a significantly lower cost. 21 refs., 1 fig., 2 tabs.

  1. Global positioning system measurements for crustal deformation: Precision and accuracy

    USGS Publications Warehouse

    Prescott, W.H.; Davis, J.L.; Svarc, J.L.

    1989-01-01

    Analysis of 27 repeated observations of Global Positioning System (GPS) position-difference vectors, up to 11 kilometers in length, indicates that the standard deviation of the measurements is 4 millimeters for the north component, 6 millimeters for the east component, and 10 to 20 millimeters for the vertical component. The uncertainty grows slowly with increasing vector length. At 225 kilometers, the standard deviation of the measurement is 6, 11, and 40 millimeters for the north, east, and up components, respectively. Measurements with GPS and Geodolite, an electromagnetic distance-measuring system, over distances of 10 to 40 kilometers agree within 0.2 part per million. Measurements with GPS and very long baseline interferometry of the 225-kilometer vector agree within 0.05 part per million.

  2. Global positioning system measurements for crustal deformation: precision and accuracy.

    PubMed

    Prescott, W H; Davis, J L; Svarc, J L

    1989-06-16

    Analysis of 27 repeated observations of Global Positioning System (GPS) position-difference vectors, up to 11 kilometers in length, indicates that the standard deviation of the measurements is 4 millimeters for the north component, 6 millimeters for the east component, and 10 to 20 millimeters for the vertical component. The uncertainty grows slowly with increasing vector length. At 225 kilometers, the standard deviation of the measurement is 6, 11, and 40 millimeters for the north, east, and up components, respectively. Measurements with GPS and Geodolite, an electromagnetic distance-measuring system, over distances of 10 to 40 kilometers agree within 0.2 part per million. Measurements with GPS and very long baseline interferometry of the 225-kilometer vector agree within 0.05 part per million. PMID:17820661

  3. Global positioning system pseudolite-based relative navigation.

    SciTech Connect

    Monda, Eric W.

    2004-03-01

    Though the Global Positioning System has revolutionized navigation in the modern age, it is limited in its capability for some applications because an unobstructed line of sight to a minimum of four satellites is required. One way of augmenting the system in small areas is by employing pseudolites to broadcast additional signals that can be used to improve the user's position solution. At the Navigation Systems Testing Laboratory (NSTL) at NASA's Johnson Space Center in Houston, TX, research has been underway on the use of pseudolites to perform precision relative navigation. Based on the findings of previous research done at the NSTL, the method used to process the pseudolite measurements is an extended Kalman filter of the double differenced carrier phase measurements. By employing simulations of the system, as well as processing previously collected data in a real time manner, sub-meter tracking of a moving receiver with carrier phase measurements in the extended Kalman filter appears to be possible.

  4. Professional rugby league positional match-play analysis through the use of global positioning system.

    PubMed

    Austin, Damien J; Kelly, Stephen J

    2014-01-01

    The purpose of this study was to quantify the movement demands of all 9 individual playing positions in professional rugby league. The movement demands of 135 professional rugby league players were recorded during 28 National Rugby League games in 2011, using a nondifferential 5 Hz global positioning system. The mean total distances covered in a game for fullback, wing, center, five-eight, halfback, hooker, lock, back row, and prop players were 7,760, 7,457, 7,301, 8,402, 8,500, 6,988, 5,481, 6,936, and 4,597 m, respectively. The average occurrence of high-intensity runs per match was 42, 35, 34, 86, 120, 74, 52, 26, and 18 for fullback, wing, center, five-eight, halfback, hooker, lock, back row, and prop players, respectively. The average distance traveled greater than 18 km·h-1 for fullback were 17 ± 2 m, wing 18 ± 2 m, center 18 ± 3 m, five-eight 16 ± 3 m, and halfback 17 ± 4 m. The average distance and range traveled greater than 18 km·h for hooker were 14 ± 3 m, lock 16 ± 2 m, back row 18 ± 3 m, and prop 16 ± 2 m. The use of global positioning systems has demonstrated plausibility to eliminate the use of grouping of positions in rugby league and for coaches to make specific training protocols for each position. Given the differences in movement demands of all 9 positions in rugby league, some positions would lack specificity to their positional requirements if using collective grouping for planning of training regimens.

  5. Global Positioning System Synchronized Active Light Autonomous Docking System

    NASA Technical Reports Server (NTRS)

    Howard, Richard T. (Inventor); Book, Michael L. (Inventor); Bryan, Thomas C. (Inventor); Bell, Joseph L. (Inventor)

    1996-01-01

    A Global Positioning System Synchronized Active Light Autonomous Docking System (GPSSALADS) for automatically docking a chase vehicle with a target vehicle comprising at least one active light emitting target which is operatively attached to the target vehicle. The target includes a three-dimensional array of concomitantly flashing lights which flash at a controlled common frequency. The GPSSALADS further comprises a visual tracking sensor operatively attached to the chase vehicle for detecting and tracking the target vehicle. Its performance is synchronized with the flash frequency of the lights by a synchronization means which is comprised of first and second internal clocks operatively connected to the active light target and visual tracking sensor, respectively, for providing timing control signals thereto, respectively. The synchronization means further includes first and second Global Positioning System receivers operatively connected to the first and second internal clocks, respectively, for repeatedly providing simultaneous synchronization pulses to the internal clocks, respectively. In addition, the GPSSALADS includes a docking process controller means which is operatively attached to the chase vehicle and is responsive to the visual tracking sensor for producing commands for the guidance and propulsion system of the chase vehicle.

  6. Global Positioning System Synchronized Active Light Autonomous Docking System

    NASA Technical Reports Server (NTRS)

    Howard, Richard (Inventor)

    1994-01-01

    A Global Positioning System Synchronized Active Light Autonomous Docking System (GPSSALADS) for automatically docking a chase vehicle with a target vehicle comprises at least one active light emitting target which is operatively attached to the target vehicle. The target includes a three-dimensional array of concomitantly flashing lights which flash at a controlled common frequency. The GPSSALADS further comprises a visual tracking sensor operatively attached to the chase vehicle for detecting and tracking the target vehicle. Its performance is synchronized with the flash frequency of the lights by a synchronization means which is comprised of first and second internal clocks operatively connected to the active light target and visual tracking sensor, respectively, for providing timing control signals thereto, respectively. The synchronization means further includes first and second Global Positioning System receivers operatively connected to the first and second internal clocks, respectively, for repeatedly providing simultaneous synchronization pulses to the internal clocks, respectively. In addition, the GPSSALADS includes a docking process controller means which is operatively attached to the chase vehicle and is responsive to the visual tracking sensor for producing commands for the guidance and propulsion system of the chase vehicle.

  7. Global Positioning System Synchronized Active Light Autonomous Docking System

    NASA Astrophysics Data System (ADS)

    Howard, Richard

    1994-08-01

    A Global Positioning System Synchronized Active Light Autonomous Docking System (GPSSALADS) for automatically docking a chase vehicle with a target vehicle comprises at least one active light emitting target which is operatively attached to the target vehicle. The target includes a three-dimensional array of concomitantly flashing lights which flash at a controlled common frequency. The GPSSALADS further comprises a visual tracking sensor operatively attached to the chase vehicle for detecting and tracking the target vehicle. Its performance is synchronized with the flash frequency of the lights by a synchronization means which is comprised of first and second internal clocks operatively connected to the active light target and visual tracking sensor, respectively, for providing timing control signals thereto, respectively. The synchronization means further includes first and second Global Positioning System receivers operatively connected to the first and second internal clocks, respectively, for repeatedly providing simultaneous synchronization pulses to the internal clocks, respectively. In addition, the GPSSALADS includes a docking process controller means which is operatively attached to the chase vehicle and is responsive to the visual tracking sensor for producing commands for the guidance and propulsion system of the chase vehicle.

  8. Global Positioning System Antenna Fixed Height Tripod Adapter

    NASA Technical Reports Server (NTRS)

    Dinardo, Steven J.; Smith, Mark A.

    1997-01-01

    An improved Global Positioning em antenna adaptor allows fixed antenna height measurements by removably attaching an adaptor plate to a conventional surveyor's tripod. Antenna height is controlled by an antenna boom which is a fixed length rod. The antenna is attached to one end of the boom. The opposite end of the boom tapers to a point sized to fit into a depression at the center of survey markers. The boom passes through the hollow center of a universal ball joint which is mounted at the center of the adaptor plate so that the point of the rod can be fixed in the marker's central depression. The mountains of the ball joint allow the joint to be moved horizontally in any direction relative to the tripod. When the ball joint is moved horizontally, the angle between the boom and the vertical changes because the boom's position is fixed at its lower end. A spirit level attached to the rod allows an operator to determine when the boom is plumb. The position of the ball joint is adjusted horizontally until the boom is plumb. At that time the antenna is positioned exactly over the center of the monument and the elevation of the antenna is precisely set by the length of the boom.

  9. High precision global positioning system for mining applications

    SciTech Connect

    O`Grady, M.

    1997-12-01

    The author discusses today`s satellite technology that has lead to the development of a system that will increase safety and production in surface mining. The Department of Defense is maintaining a satellite system made up of 24 NavStar satellites that allow the use of their frequencies to position equipment anywhere on Earth. The previous satellite system was called the Transit system or Sat-Nav. It consisted of low-orbit satellites (not many up there) that ground-based receivers needed three days of logged data to process sub-meter accuracy positions. With the NavStar network of satellites, centimeter accuracy can be achieved within just a few minutes. Changes to the way one used to survey in the mining industry are being replaced with the Global Positioning System. It has proven to be a system that is more accurate and after the typical learning curve that is required by any new system, will lead to higher productivity; hence, financial rewards are in the immediate future.

  10. Autonomous satellite navigation methods using the Global Positioning Satellite System

    NASA Technical Reports Server (NTRS)

    Murata, M.; Tapley, B. D.; Schutz, B. E.

    1982-01-01

    This investigation considers the problem of autonomous satellite navigation using the NAVSTAR Global Positioning System (GPS). The major topics covered include the design, implementation, and validation of onboard navigation filter algorithms by means of computer simulations. The primary errors that the navigation filter design must minimize are computational effects and modeling inaccuracies due to limited capability of the onboard computer. The minimization of the effect of these errors is attained by applying the sequential extended Kalman filter using a factored covariance implementation with Q-matrix or dynamical model compensations. Peformance evaluation of the navigation filter design is carried out using both the CDC Cyber 170/750 computer and the PDP-11/60 computer. The results are obtained assuming the Phase I GPS constellation, consisting of six satellites, and a Landsat-D type spacecraft as the model for the user satellite orbit.

  11. Launch vehicle tracking enhancement through Global Positioning System Metric Tracking

    NASA Astrophysics Data System (ADS)

    Moore, T. C.; Li, Hanchu; Gray, T.; Doran, A.

    United Launch Alliance (ULA) initiated operational flights of both the Atlas V and Delta IV launch vehicle families in 2002. The Atlas V and Delta IV launch vehicles were developed jointly with the US Air Force (USAF) as part of the Evolved Expendable Launch Vehicle (EELV) program. Both Launch Vehicle (LV) families have provided 100% mission success since their respective inaugural launches and demonstrated launch capability from both Vandenberg Air Force Base (VAFB) on the Western Test Range and Cape Canaveral Air Force Station (CCAFS) on the Eastern Test Range. However, the current EELV fleet communications, tracking, & control architecture & technology, which date back to the origins of the space launch business, require support by a large and high cost ground footprint. The USAF has embarked on an initiative known as Future Flight Safety System (FFSS) that will significantly reduce Test Range Operations and Maintenance (O& M) cost by closing facilities and decommissioning ground assets. In support of the FFSS, a Global Positioning System Metric Tracking (GPS MT) System based on the Global Positioning System (GPS) satellite constellation has been developed for EELV which will allow both Ranges to divest some of their radar assets. The Air Force, ULA and Space Vector have flown the first 2 Atlas Certification vehicles demonstrating the successful operation of the GPS MT System. The first Atlas V certification flight was completed in February 2012 from CCAFS, the second Atlas V certification flight from VAFB was completed in September 2012 and the third certification flight on a Delta IV was completed October 2012 from CCAFS. The GPS MT System will provide precise LV position, velocity and timing information that can replace ground radar tracking resource functionality. The GPS MT system will provide an independent position/velocity S-Band telemetry downlink to support the current man-in-the-loop ground-based commanded destruct of an anomalous flight- The system

  12. Helicopter approach capability using the differential Global Positioning System

    NASA Technical Reports Server (NTRS)

    Kaufmann, David N.

    1993-01-01

    The results of flight tests to determine the feasibility of using the Global Positioning System (GPS) in the differential mode (DGPS) to provide high accuracy, precision navigation and guidance for helicopter approaches to landing are presented. The airborne DGPS receiver and associated equipment is installed in a NASA UH-60 Black Hawk helicopter. The ground-based DGPS reference receiver is located at a surveyed test site and is equipped with a real-time VHF data link to transmit correction information to the airborne DGPS receiver. The corrected airborne DGPS information, together with the preset approach geometry, is used to calculate guidance commands which are sent to the aircraft's approach guidance instruments. The use of DGPS derived guidance for helicopter approaches to landing is evaluated by comparing the DGPS data with the laser tracker truth data. Both standard (3 degrees) and steep (6 degrees and 9 degrees) glidescope straight-in approaches were flown. DGPS positioning accuracy based on a time history analysis of the entire approach was 0.2 m (mean) +/- 1.8 m (2 sigma) laterally and -2.0 m (mean) +/- 3.5 m (2 sigma) vertically for 3 degree glidescope approaches, -0.1 m (mean) +/- 1.5 m (2 sigma) laterally and -1.1 m (mean) +/- 3.5 m (2 sigma) vertically for 6 degree glidescope approaches, and 0.2 m (mean) +/- 1.3 m (2 sigma) laterally and -1.0 m (mean) +/- 2.8 (2 sigma) vertically for 9 degree glidescope approaches. DGPS positioning accuracy at the 200 ft decision height on a standard 3 degree glidescope approach was 0.3 m (mean) +/- 1.5 m (2 sigma) laterally and -2.3 m (mean) +/- 1.6 m (2 sigma) vertically. These errors indicate that the helicopter position based on DGPS guidance satisfies the International Civil Aviation Organization Category 1 lateral and vertical accuracy requirements.

  13. Blind separation of positive sources by globally convergent gradient search.

    PubMed

    Oja, Erkki; Plumbley, Mark

    2004-09-01

    The instantaneous noise-free linear mixing model in independent component analysis is largely a solved problem under the usual assumption of independent nongaussian sources and full column rank mixing matrix. However, with some prior information on the sources, like positivity, new analysis and perhaps simplified solution methods may yet become possible. In this letter, we consider the task of independent component analysis when the independent sources are known to be nonnegative and well grounded, which means that they have a nonzero pdf in the region of zero. It can be shown that in this case, the solution method is basically very simple: an orthogonal rotation of the whitened observation vector into nonnegative outputs will give a positive permutation of the original sources. We propose a cost function whose minimum coincides with nonnegativity and derive the gradient algorithm under the whitening constraint, under which the separating matrix is orthogonal. We further prove that in the Stiefel manifold of orthogonal matrices, the cost function is a Lyapunov function for the matrix gradient flow, implying global convergence. Thus, this algorithm is guaranteed to find the nonnegative well-grounded independent sources. The analysis is complemented by a numerical simulation, which illustrates the algorithm. PMID:15265323

  14. Modeling the global positioning system signal propagation through the ionosphere

    NASA Technical Reports Server (NTRS)

    Bassiri, S.; Hajj, G. A.

    1992-01-01

    Based on realistic modeling of the electron density of the ionosphere and using a dipole moment approximation for the Earth's magnetic field, one is able to estimate the effect of the ionosphere on the Global Positioning System (GPS) signal for a ground user. The lowest order effect, which is on the order of 0.1-100 m of group delay, is subtracted out by forming a linear combination of the dual frequencies of the GPS signal. One is left with second- and third-order effects that are estimated typically to be approximately 0-2 cm and approximately 0-2 mm at zenith, respectively, depending on the geographical location, the time of day, the time of year, the solar cycle, and the relative geometry of the magnetic field and the line of sight. Given the total electron content along a line of sight, the authors derive an approximation to the second-order term which is accurate to approximately 90 percent within the magnetic dipole moment model; this approximation can be used to reduce the second-order term to the millimeter level, thus potentially improving precise positioning in space and on the ground. The induced group delay, or phase advance, due to second- and third-order effects is examined for two ground receivers located at equatorial and mid-latitude regions tracking several GPS satellites.

  15. Helicopter Approach Capability Using the Differential Global Positioning System

    NASA Technical Reports Server (NTRS)

    Kaufmann, David N.

    1994-01-01

    The results of flight tests to determine the feasibility of using the Global Positioning System (GPS) in the Differential mode (DGPS) to provide high accuracy, precision navigation and guidance for helicopter approaches to landing are presented. The airborne DGPS receiver and associated equipment is installed in a NASA UH-60 Black Hawk helicopter. The ground-based DGPS reference receiver is located at a surveyed test site and is equipped with a real-time VHF data link to transmit correction information to the airborne DGPS receiver. The corrected airborne DGPS information, together with the preset approach geometry, is used to calculate guidance commands which are sent to the aircraft's approach guidance instruments. The use of DGPS derived guidance for helicopter approaches to landing is evaluated by comparing the DGPS data with the laser tracker truth data. The errors indicate that the helicopter position based on DGPS guidance satisfies the International Civil Aviation Organization (ICAO) Category 1 (CAT 1) lateral and vertical navigational accuracy requirements.

  16. Workshop Builds Strategies to Address Global Positioning System Vulnerabilities

    NASA Astrophysics Data System (ADS)

    Fisher, Genene

    2011-01-01

    When we examine the impacts of space weather on society, do we really understand the risks? Can past experiences reliably predict what will happen in the future? As the complexity of technology increases, there is the potential for it to become more fragile, allowing for a single point of failure to bring down the entire system. Take the Global Positioning System (GPS) as an example. GPS positioning, navigation, and timing have become an integral part of daily life, supporting transportation and communications systems vital to the aviation, merchant marine, cargo, cellular phone, surveying, and oil exploration industries. Everyday activities such as banking, mobile phone operations, and even the control of power grids are facilitated by the accurate timing provided by GPS. Understanding the risks of space weather to GPS and the many economic sectors reliant upon it, as well as how to build resilience, was the focus of a policy workshop organized by the American Meteorological Society (AMS) and held on 13-14 October 2010 in Washington, D. C. The workshop brought together a select group of policy makers, space weather scientists, and GPS experts and users.

  17. Volcano monitoring using the Global Positioning System: Filtering strategies

    USGS Publications Warehouse

    Larson, K.M.; Cervelli, Peter; Lisowski, M.; Miklius, Asta; Segall, P.; Owen, S.

    2001-01-01

    Permanent Global Positioning System (GPS) networks are routinely used for producing improved orbits and monitoring secular tectonic deformation. For these applications, data are transferred to an analysis center each day and routinely processed in 24-hour segments. To use GPS for monitoring volcanic events, which may last only a few hours, real-time or near real-time data processing and subdaily position estimates are valuable. Strategies have been researched for obtaining station coordinates every 15 min using a Kalman filter; these strategies have been tested on data collected by a GPS network on Kilauea Volcano. Data from this network are tracked continuously, recorded every 30 s, and telemetered hourly to the Hawaiian Volcano Observatory. A white noise model is heavily impacted by data outages and poor satellite geometry, but a properly constrained random walk model fits the data well. Using a borehole tiltmeter at Kilauea's summit as ground-truth, solutions using different random walk constraints were compared. This study indicates that signals on the order of 5 mm/h are resolvable using a random walk standard deviation of 0.45 cm/???h. Values lower than this suppress small signals, and values greater than this have significantly higher noise at periods of 1-6 hours. Copyright 2001 by the American Geophysical Union.

  18. Quantifying positional and temporal movement patterns in professional rugby union using global positioning system.

    PubMed

    Jones, Marc R; West, Daniel J; Crewther, Blair T; Cook, Christian J; Kilduff, Liam P

    2015-01-01

    This study assessed the positional and temporal movement patterns of professional rugby union players during competition using global positioning system (GPS) units. GPS data were collected from 33 professional rugby players from 13 matches throughout the 2012-2013 season sampling at 10 Hz. Players wore GPS units from which information on distances, velocities, accelerations, exertion index, player load, contacts, sprinting and repeated high-intensity efforts (RHIE) were derived. Data files from players who played over 60 min (n = 112) were separated into five positional groups (tight and loose forwards; half, inside and outside backs) for match analysis. A further comparison of temporal changes in movement patterns was also performed using data files from those who played full games (n = 71). Significant positional differences were found for movement characteristics during performance (P < 0.05). Results demonstrate that inside and outside backs have greatest high-speed running demands; however, RHIE and contact demands are greatest in loose forwards during match play. Temporal analysis of all players displayed significant differences in player load, cruising and striding between halves, with measures of low- and high-intensity movement and acceleration/deceleration significantly declining throughout each half. Our data demonstrate significant positional differences for a number of key movement variables which provide a greater understanding of positional requirements of performance. This in turn may be used to develop progressive position-specific drills that elicit specific adaptations and provide objective measures of preparedness. Knowledge of performance changes may be used when developing drills and should be considered when monitoring and evaluating performance.

  19. 76 FR 33022 - Eighty-Sixth Meeting: RTCA Special Committee 159: Global Positioning System (GPS)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-07

    ... Federal Aviation Administration Eighty-Sixth Meeting: RTCA Special Committee 159: Global Positioning... 159 meeting: Global Positioning System (GPS). SUMMARY: The FAA is issuing this notice to advise the public of a meeting of RTCA Special Committee 159: Global Positioning System (GPS). DATES: The...

  20. 75 FR 28318 - Eighty-Second Meeting: RTCA Special Committee 159: Global Positioning System (GPS)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-20

    ... Federal Aviation Administration Eighty-Second Meeting: RTCA Special Committee 159: Global Positioning... 159 meeting: Global Positioning System (GPS). SUMMARY: The FAA is issuing this notice to advise the public of a meeting of RTCA Special Committee 159: Global Positioning System (GPS). DATES: The...

  1. 77 FR 56254 - 89th Meeting: RTCA Special Committee 159, Global Positioning Systems (GPS)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-12

    ... Federal Aviation Administration 89th Meeting: RTCA Special Committee 159, Global Positioning Systems (GPS... Notice of RTCA Special Committee 159, RTCA Special Committee 159, Global Positioning Systems (GPS... Special Committee 159, Global Positioning Systems (GPS). DATES: The meeting will be held October 5,...

  2. 78 FR 57672 - 91st Meeting: RTCA Special Committee 159, Global Positioning Systems (GPS)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-19

    ... Federal Aviation Administration 91st Meeting: RTCA Special Committee 159, Global Positioning Systems (GPS... Notice of RTCA Special Committee 159, RTCA Special Committee 159, Global Positioning Systems (GPS... Special Committee 159, Global Positioning Systems (GPS) DATES: The meeting will be held October 7-11,...

  3. 78 FR 13396 - 90th Meeting: RTCA Special Committee 159, Global Positioning Systems (GPS)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-27

    ... Federal Aviation Administration 90th Meeting: RTCA Special Committee 159, Global Positioning Systems (GPS... Notice of RTCA Special Committee 159, RTCA Special Committee 159, Global Positioning Systems (GPS... Special Committee 159, Global Positioning Systems (GPS). DATES: The meeting will be held March 12-15,...

  4. 75 FR 2581 - Eighty-First Meeting: RTCA Special Committee 159: Global Positioning System (GPS)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-15

    ... Federal Aviation Administration Eighty-First Meeting: RTCA Special Committee 159: Global Positioning... 159 meeting: Global Positioning System (GPS). SUMMARY: The FAA is issuing this notice to advise the public of a meeting of RTCA Special Committee 159: Global Positioning System (GPS). DATES: The...

  5. 76 FR 67019 - Eighty-Seventh: RTCA Special Committee 159: Global Positioning System (GPS)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-28

    ... Federal Aviation Administration Eighty-Seventh: RTCA Special Committee 159: Global Positioning System (GPS... RTCA Special Committee 159 meeting: Global Positioning System (GPS). SUMMARY: The FAA is issuing this notice to advise the public of a meeting of RTCA Special Committee 159: Global Positioning System...

  6. 76 FR 27744 - Eighty-Fifth Meeting: RTCA Special Committee 159: Global Positioning System (GPS)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-12

    ... Federal Aviation Administration Eighty-Fifth Meeting: RTCA Special Committee 159: Global Positioning... 159 meeting: Global Positioning System (GPS). SUMMARY: The FAA is issuing this notice to advise the public of a meeting of RTCA Special Committee 159: Global Positioning System (GPS). DATES: The...

  7. 77 FR 12106 - 88th Meeting: RTCA Special Committee 159, Global Positioning System (GPS)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-28

    ... Federal Aviation Administration 88th Meeting: RTCA Special Committee 159, Global Positioning System (GPS... RTCA Special Committee 159, Global Positioning System (GPS). SUMMARY: The FAA is issuing this notice to advise the public of the 88th meeting of RTCA Special Committee 159, Global Positioning System...

  8. Global positioning system watches for estimating energy expenditure.

    PubMed

    Hongu, Nobuko; Orr, Barron J; Roe, Denise J; Reed, Rebecca G; Going, Scott B

    2013-11-01

    Global positioning system (GPS) watches have been introduced commercially, converting frequent measurements of time, location, speed (pace), and elevation into energy expenditure (EE) estimates. The purpose of this study was to compare EE estimates of 4 different GPS watches (Forerunner, Suunto, Polar, Adeo), at various walking speeds, with EE estimate from a triaxial accelerometer (RT3), which was used as a reference measure in this study. Sixteen healthy young adults completed the study. Participants wore 4 different GPS watches and an RT3 accelerometer and walked at 6-minute intervals on an outdoor track at 3 speeds (3, 5, and 7 km/hr). The statistical significance of differences in EE between the 3 watches was assessed using linear contrasts of the coefficients from the overall model. Reliability across trials for a given device was assessed using intraclass correlation coefficients as estimated in the mixed model. The GPS watches demonstrated lower reliability (intraclass correlation coefficient) across trials when compared with the RT3, particularly at the higher speed, 7 km/hr. Three GPS watches (Forerunner, Polar, and Suunto) significantly and consistently underestimated EE compared with the reference EE given by the RT3 accelerometer (average mean difference: Garmin, -50.5%; Polar, -41.7%; and Suunto, -41.7%; all p < 0.001). Results suggested that caution should be exercised when using commercial GPS watches to estimate EE in athletes during field-based testing and training.

  9. Predictive Attitude Estimation Using Global Positioning System Signals

    NASA Technical Reports Server (NTRS)

    Crassidis, John L.; Markley, F. Landis; Lightsey, E. Glenn; Ketchum, Eleanor

    1997-01-01

    In this paper, a new algorithm is developed for attitude estimation using Global Positioning System (GPS) signals. The new algorithm is based on a predictive filtering scheme designed for spacecraft without rate measuring devices. The major advantage of this new algorithm over traditional Kalman filter approaches is that the model error is not assumed to represented by an unbiased Gaussian noise process with known covariance, but instead is determined during the estimation process. This is achieved by simultaneously solving system optimality conditions and an output error constraint. This approach is well suited for GPS attitude estimation since some error sources that contribute to attitude inaccuracy, such as signal multipath, are known to be non-Gaussian processes. Also, the predictive filter scheme can use either GPS signals or vector observations or a combination of both for attitude estimation, so that performance characteristics can be maintained during periods of GPS attitude sensor outage. The performance of the new algorithm is tested using flight data from the REX-2 spacecraft. Results are shown using the predictive filter to estimate the attitude from both GPS signals and magnetometer measurements, and comparing that solution to a magnetometer-only based solution. Results using the new estimation algorithm indicate that GPS-based solutions are verified to within 2 degrees using the magnetometer cross-check for the REX-2 spacecraft. GPS attitude accuracy of better than 1 degree is expected per axis, but cannot be reliably proven due to inaccuracies in the magnetic field model.

  10. Tightly Coupled Inertial Navigation System/Global Positioning System (TCMIG)

    NASA Technical Reports Server (NTRS)

    Watson, Michael D.; Jackson, Kurt (Technical Monitor)

    2002-01-01

    Many NASA applications planned for execution later this decade are seeking high performance, miniaturized, low power Inertial Management Units (IMU). Much research has gone into Micro-Electro-Mechanical System (MEMS) over the past decade as a solution to these needs. While MEMS devices have proven to provide high accuracy acceleration measurements, they have not yet proven to have the accuracy required by many NASA missions in rotational measurements. Therefore, a new solution has been formulated integrating the best of all IMU technologies to address these mid-term needs in the form of a Tightly Coupled Micro Inertial Navigation System (INS)/Global Positioning System (GPS) (TCMIG). The TCMIG consists of an INS and a GPS tightly coupled by a Kalman filter executing on an embedded Field Programmable Gate Array (FPGA) processor. The INS consists of a highly integrated Interferometric Fiber Optic Gyroscope (IFOG) and a MEMS accelerometer. The IFOG utilizes a tightly wound fiber coil to reduce volume and the high level of integration and advanced optical components to reduce power. The MEMS accelerometer utilizes a newly developed deep etch process to increase the proof mass and yield a highly accurate accelerometer. The GPS receiver consists of a low power miniaturized version of the Blackjack receiver. Such an IMU configuration is ideal to meet the mid-term needs of the NASA Science Enterprises and the new launch vehicles being developed for the Space Launch Initiative (SLI).

  11. Accuracy of non-differential GPS for the determination of speed over ground.

    PubMed

    Witte, T H; Wilson, A M

    2004-12-01

    Accurate determination of speed is important in many studies of human and animal locomotion. Some global positioning system (GPS) receivers can data log instantaneous speed. The speed accuracy of these systems is, however, unclear with manufacturers reporting velocity accuracies of 0.1-0.2 ms(-1). This study set out to trial non-differential GPS as a means of determining speed under real-life conditions. A bicycle was ridden around a running track and a custom-made bicycle speedometer was calibrated. Additional experiments were performed around circular tracks of known circumference and along a straight road. Instantaneous speed was determined simultaneously by the custom speedometer and a data logging helmet-mounted GPS receiver. GPS speed was compared to speedometer speed. The effect on speed accuracy of satellite number; changing satellite geometry, achieved through shielding the GPS antenna; speed; horizontal dilution of precision and cyclist position on a straight or a bend, was evaluated. The relative contribution of each variable to overall speed accuracy was determined by ANOVA. The speed determined by the GPS receiver was within 0.2 ms(-1) of the true speed measured for 45% of the values with a further 19% lying within 0.4 ms(-1) (n = 5060). The accuracy of speed determination was preserved even when the positional data were degraded due to poor satellite number or geometry. GPS data loggers are therefore accurate for the determination of speed over-ground in biomechanical and energetic studies performed on relatively straight courses. Errors increase on circular paths, especially those with small radii of curvature, due to a tendency to underestimate speed.

  12. Global Organization of a Positive-strand RNA Virus Genome

    PubMed Central

    Wu, Baodong; Grigull, Jörg; Ore, Moriam O.; Morin, Sylvie; White, K. Andrew

    2013-01-01

    The genomes of plus-strand RNA viruses contain many regulatory sequences and structures that direct different viral processes. The traditional view of these RNA elements are as local structures present in non-coding regions. However, this view is changing due to the discovery of regulatory elements in coding regions and functional long-range intra-genomic base pairing interactions. The ∼4.8 kb long RNA genome of the tombusvirus tomato bushy stunt virus (TBSV) contains these types of structural features, including six different functional long-distance interactions. We hypothesized that to achieve these multiple interactions this viral genome must utilize a large-scale organizational strategy and, accordingly, we sought to assess the global conformation of the entire TBSV genome. Atomic force micrographs of the genome indicated a mostly condensed structure composed of interconnected protrusions extending from a central hub. This configuration was consistent with the genomic secondary structure model generated using high-throughput selective 2′-hydroxyl acylation analysed by primer extension (i.e. SHAPE), which predicted different sized RNA domains originating from a central region. Known RNA elements were identified in both domain and inter-domain regions, and novel structural features were predicted and functionally confirmed. Interestingly, only two of the six long-range interactions known to form were present in the structural model. However, for those interactions that did not form, complementary partner sequences were positioned relatively close to each other in the structure, suggesting that the secondary structure level of viral genome structure could provide a basic scaffold for the formation of different long-range interactions. The higher-order structural model for the TBSV RNA genome provides a snapshot of the complex framework that allows multiple functional components to operate in concert within a confined context. PMID:23717202

  13. Precise mean sea level measurements using the Global Positioning System

    NASA Technical Reports Server (NTRS)

    Kelecy, Thomas M.; Born, George H.; Parke, Michael E.; Rocken, Christian

    1994-01-01

    This paper describes the results of a sea level measurement test conducted off La Jolla, California, in November of 1991. The purpose of this test was to determine accurate sea level measurements using a Global Positioning System (GPS) equipped buoy. These measurements were intended to be used as the sea level component for calibration of the ERS 1 satellite altimeter. Measurements were collected on November 25 and 28 when the ERS 1 satellite overflew the calibration area. Two different types of buoys were used. A waverider design was used on November 25 and a spar design on November 28. This provided the opportunity to examine how dynamic effects of the measurement platform might affect the sea level accuracy. The two buoys were deployed at locations approximately 1.2 km apart and about 15 km west of a reference GPS receiver located on the rooftop of the Institute of Geophysics and Planetary Physics at the Scripps Institute of Oceanography. GPS solutions were computed for 45 minutes on each day and used to produce two sea level time series. An estimate of the mean sea level at both locations was computed by subtracting tide gage data collected at the Scripps Pier from the GPS-determined sea level measurements and then filtering out the high-frequency components due to waves and buoy dynamics. In both cases the GPS estimate differed from Rapp's mean altimetric surface by 0.06 m. Thus, the gradient in the GPS measurements matched the gradient in Rapp's surface. These results suggest that accurate sea level can be determined using GPS on widely differing platforms as long as care is taken to determine the height of the GPS antenna phase center above water level. Application areas include measurement of absolute sea level, of temporal variations in sea level, and of sea level gradients (dominantly the geoid). Specific applications would include ocean altimeter calibration, monitoring of sea level in remote regions, and regional experiments requiring spatial and

  14. Design studies for a technology assessment receiver for global positioning system

    NASA Technical Reports Server (NTRS)

    Painter, J. H.

    1981-01-01

    The operational conditions of a radio receiver - microprocessor for the global positioning system are studied. Navigation fundamentals and orbit characterization are reviewed. The global positioning system is described with emphasis upon signal structure and satellite positioning. Ranging and receiver processing techniques are discussed.

  15. Positioning Multicultural Education across the Mirror of Globalization

    ERIC Educational Resources Information Center

    Oikonomidoy, Eleni

    2015-01-01

    The graduate level course described in this article provides one possible pathway to making the connection between the global and the local in multicultural education. The proposal is that among many other things, the journey to the development of critical approaches is a conceptual endeavor. It is not meant to replace an introductory course in…

  16. Determination of locational error associated with global positioning system (GPS) radio collars in relation to vegetation and topography in north-central New Mexico

    SciTech Connect

    Bennett, K.; Biggs, J.; Fresquez, P.R.

    1997-02-01

    In 1996, a study was initiated to assess seasonal habitat use and movement patterns of Rocky Mountain elk (Cervus elaphus nelsoni) using global positioning system (GPS) radio collars. As part of this study, the authors attempted to assess the accuracies of GPS (non-differentially corrected) positions under various vegetation canopies and terrain conditions with the use of a GPS ``test`` collar. The test collar was activated every twenty minutes to obtain a position location and continuously uplinked to Argos satellites to transfer position data files. They used a Telonics, Inc. uplink receiver to intercept the transmission and view the results of the collar in real time. They placed the collar on a stand equivalent to the neck height of an adult elk and then placed the stand within three different treatment categories: (1) topographical influence (canyon and mesa tops), (2) canopy influence (open and closed canopy), and (3) vegetation type influence (ponderosa pine and pinion pine-juniper). The collar was kept at each location for one hour (usually obtaining three fixes). In addition, the authors used a hand-held GPS to obtain a position of the test collar at the same time and location.

  17. Estimation of Subdaily Polar Motion with the Global Positioning System During the Spoch '92 Campaign

    NASA Technical Reports Server (NTRS)

    Ibanez-Meier, R.; Freedman, A. P.; Herring, T. A.; Gross, R. S.; Lichten, S. M.; Lindqwister, U. J.

    1994-01-01

    Data collected over six days from a worldwide Global Positioning System (GPS) tracking network during the Epoch '92 campaign are used to estimate variations of the Earth's pole position every 30 minutes.

  18. 75 FR 14658 - Invitation for Public Comment on Mitigation Options for Global Positioning System Satellite...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-26

    ... Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78) or you may... Global Positioning System Satellite Vehicle Number 49 AGENCY: Research and Innovative Technology... Global Positioning System (GPS) satellite IIR-20M (satellite vehicle number 49--SVN 49) from unhealthy...

  19. Criterion validity and accuracy of global positioning satellite and data logging devices for wheelchair tennis court movement

    PubMed Central

    Sindall, Paul; Lenton, John P.; Whytock, Katie; Tolfrey, Keith; Oyster, Michelle L.; Cooper, Rory A.; Goosey-Tolfrey, Victoria L.

    2013-01-01

    Purpose To compare the criterion validity and accuracy of a 1 Hz non-differential global positioning system (GPS) and data logger device (DL) for the measurement of wheelchair tennis court movement variables. Methods Initial validation of the DL device was performed. GPS and DL were fitted to the wheelchair and used to record distance (m) and speed (m/second) during (a) tennis field (b) linear track, and (c) match-play test scenarios. Fifteen participants were monitored at the Wheelchair British Tennis Open. Results Data logging validation showed underestimations for distance in right (DLR) and left (DLL) logging devices at speeds >2.5 m/second. In tennis-field tests, GPS underestimated distance in five drills. DLL was lower than both (a) criterion and (b) DLR in drills moving forward. Reversing drill direction showed that DLR was lower than (a) criterion and (b) DLL. GPS values for distance and average speed for match play were significantly lower than equivalent values obtained by DL (distance: 2816 (844) vs. 3952 (1109) m, P = 0.0001; average speed: 0.7 (0.2) vs. 1.0 (0.2) m/second, P = 0.0001). Higher peak speeds were observed in DL (3.4 (0.4) vs. 3.1 (0.5) m/second, P = 0.004) during tennis match play. Conclusions Sampling frequencies of 1 Hz are too low to accurately measure distance and speed during wheelchair tennis. GPS units with a higher sampling rate should be advocated in further studies. Modifications to existing DL devices may be required to increase measurement precision. Further research into the validity of movement devices during match play will further inform the demands and movement patterns associated with wheelchair tennis. PMID:23820154

  20. Global shifts towards positive species interactions with increasing environmental stress.

    PubMed

    He, Qiang; Bertness, Mark D; Altieri, Andrew H

    2013-05-01

    The study of positive species interactions is a rapidly evolving field in ecology. Despite decades of research, controversy has emerged as to whether positive and negative interactions predictably shift with increasing environmental stress as hypothesised by the stress-gradient hypothesis (SGH). Here, we provide a synthesis of 727 tests of the SGH in plant communities across the globe to examine its generality across a variety of ecological factors. Our results show that plant interactions change with stress through an outright shift to facilitation (survival) or a reduction in competition (growth and reproduction). In a limited number of cases, plant interactions do not respond to stress, but they never shift towards competition with stress. These findings are consistent across stress types, plant growth forms, life histories, origins (invasive vs. native), climates, ecosystems and methodologies, though the magnitude of the shifts towards facilitation with stress is dependent on these factors. We suggest that future studies should employ standardised definitions and protocols to test the SGH, take a multi-factorial approach that considers variables such as plant traits in addition to stress, and apply the SGH to better understand how species and communities will respond to environmental change.

  1. Office of Spaceflight Standard Spaceborne Global Positioning System (GPS) user equipment project

    NASA Technical Reports Server (NTRS)

    Saunders, Penny E.

    1991-01-01

    The Global Positioning System (GPS) provides the following: (1) position and velocity determination to support vehicle GN&C, precise orbit determination, and payload pointing; (2) time reference to support onboard timing systems and data time tagging; (3) relative position and velocity determination to support cooperative vehicle tracking; and (4) attitude determination to support vehicle attitude control and payload pointing.

  2. GPS aiding of ocean current determination. [Global Positioning System

    NASA Technical Reports Server (NTRS)

    Mohan, S. N.

    1981-01-01

    The navigational accuracy of an oceangoing vessel using conventional GPS p-code data is examined. The GPS signal is transmitted over two carrier frequencies in the L-band at 1575.42 and 1227.6 MHz. Achievable navigational uncertainties of differenced positional estimates are presented as a function of the parameters of the problem, with particular attention given to the effect of sea-state, user equivalent range error, uncompensated antenna motion, varying delay intervals, and reduced data rate examined in the unaided mode. The unmodeled errors resulting from satellite ephemeris uncertainties are shown to be negligible for the GPS-NDS (Navigation Development) satellites. Requirements are met in relatively calm seas, but accuracy degradation by a factor of at least 2 must be anticipated in heavier sea states. The aided mode of operation is examined, and it is shown that requirements can be met by using an inertial measurement unit (IMU) to aid the GPS receiver operation. Since the use of an IMU would mean higher costs, direct Doppler from the GPS satellites is presented as a viable alternative.

  3. Positional Accuracy of Airborne Integrated Global Positioning and Inertial Navigation Systems for Mapping in Glen Canyon, Arizona

    USGS Publications Warehouse

    Sanchez, Richard D.; Hothem, Larry D.

    2002-01-01

    High-resolution airborne and satellite image sensor systems integrated with onboard data collection based on the Global Positioning System (GPS) and inertial navigation systems (INS) may offer a quick and cost-effective way to gather accurate topographic map information without ground control or aerial triangulation. The Applanix Corporation?s Position and Orientation Solutions for Direct Georeferencing of aerial photography was used in this project to examine the positional accuracy of integrated GPS/INS for terrain mapping in Glen Canyon, Arizona. The research application in this study yielded important information on the usefulness and limits of airborne integrated GPS/INS data-capture systems for mapping.

  4. Using The Global Positioning System For Earth Orbiter and Deep Space Network

    NASA Technical Reports Server (NTRS)

    Lichten, Stephen M.; Haines, Bruce J.; Young, Lawrence E.; Dunn, Charles; Srinivasan, Jeff; Sweeney, Dennis; Nandi, Sumita; Spitzmesser, Don

    1994-01-01

    The Global Positioning System (GPS) can play a major role in supporting orbit and trajectory determination for spacecraft in a wide range of applications, including low-Earth, high-earth, and even deep space (interplanetary) tracking.

  5. 76 FR 31943 - Global Positioning System Directorate (Gpsd); Notice of Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-02

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF DEFENSE Department of the Air Force Global Positioning System Directorate (Gpsd); Notice of Meeting ACTION: Notice of..., IS-GPS-705A, IS-GPS-800A). SUMMARY: This notice informs the public that the Global...

  6. Daily estimates of the earth's pole position with the Global Positioning System

    NASA Technical Reports Server (NTRS)

    Lindqwister, Ulf J.; Freedman, Adam P.; Blewitt, Geoffrey

    1992-01-01

    Daily estimates of the earth's pole position have been obtained with measurements from a worldwide network of GPS receivers, obtained during the three week GIG '91 experiment in January-February 1991. For this short-term study, the GPS based polar motion series agrees with the other space based geodetic techniques (Very Long Baseline Interferometry and Satellite Laser Ranging) to about 0.4 mas rms, after the removal of mean biases of order 1-3 mas. The small error in day-to-day variability is not sensitive to the fiducial strategy used, nor are fiducial sites even necessary for monitoring high frequency pole position variability. The small biases indicate that the applied reference frames of the three geodetic techniques are nearly aligned, that the GPS fiducial errors are small, and that systematic errors in GPS are also small (of order 5 ppb). A well determined reference frame is necessary for monitoring the long-term stability of polar motion and for separating it from other long-term signals such as tectonic motion and internal systematic errors.

  7. The Global Positioning System and Its Integration into College Geography Curricula.

    ERIC Educational Resources Information Center

    Wikle, Thomas A.; Lambert, Dean P.

    1996-01-01

    Introduces global positioning system (GPS) technology to nonspecialist geographers and recommends a framework for implementing GPS instructional modules in college geography courses. GPS was developed as a worldwide satellite-based system by the U.S. Department of Defense to simplify and improve military and civilian navigation and positioning.…

  8. Contributions of Positive Psychology to Peace: Toward Global Well-Being and Resilience

    ERIC Educational Resources Information Center

    Cohrs, J. Christopher; Christie, Daniel J.; White, Mathew P.; Das, Chaitali

    2013-01-01

    In this article, we analyze the relationship between positive psychology and peace psychology. We discuss how positive emotions, engagement, meaning, personal well-being, and resilience may impact peace at different levels, ranging from the personal and interpersonal to community, national, and global peace. First, we argue that an…

  9. The Global Positioning System--Direction for the Future [and] GPS Technology and Agriculture.

    ERIC Educational Resources Information Center

    Edmondson, Paul R.; Ginsburg, Alan

    1996-01-01

    Edmondson introduces a satellite-based radio navigation, positioning, and timing system that can be integrated into a variety of curriculum areas. Ginsburg describes how the global positioning system brings far-reaching benefits for crop growers and the environment. (Author)

  10. TOPEX orbit determination and gravity recovery using Global Positioning System data from repeat orbits

    NASA Technical Reports Server (NTRS)

    Wu, Jiun-Tsong; Yunck, Thomas P.

    1992-01-01

    A covariance analysis is presented for satellite tracking and gravity recovery with a differential Global Positioning System-based technique to be demonstrated on TOPEX in the early 1990s. The technique employs data from an ensemble of repeat ground tracks to recover a unique satellite epoch state for each track and a set of invariant positional parameters common to all tracks. The positional parameters represent the effect of mismodeled gravitational field on the satellite orbit. At an altitude of 1336 km, where gravity modeling is the dominant systematic error, averaging of random error over many arcs and adjustment of the gravity model reduce the final satellite position error. The positional parameters can then be used to produce a refined global gravity model. The analysis indicates that errors ranging from 5 to 8 cm in TOPEX altitude and 0.05 to 0.2 mGal for the gravity field can be achieved, depending on the number of repeat arcs used.

  11. Contributions of positive psychology to peace: toward global well-being and resilience.

    PubMed

    Cohrs, J Christopher; Christie, Daniel J; White, Mathew P; Das, Chaitali

    2013-10-01

    In this article, we analyze the relationship between positive psychology and peace psychology. We discuss how positive emotions, engagement, meaning, personal well-being, and resilience may impact peace at different levels, ranging from the personal and interpersonal to community, national, and global peace. First, we argue that an individual's positive experiences, personal well-being, and personal resilience, as defined in current positive psychology, may in fact contribute to personal and interpersonal peace but can also entail detrimental consequences for other individuals, communities, and nations. Second, we describe how peace psychology contains traces of positive psychology, especially with its focus on the pursuit of social justice. Third, reviewing and extending the concept of community resilience, we outline directions for further conceptual and empirical work in positive psychology inspired by peace psychology. Such work would do well to transcend positive psychology's current bias toward individualism and nationalism and to conceptualize well-being and resilience at the level of the "global community." This extended "positive peace psychology" perspective would have important implications for our understanding of how to overcome oppression and work toward global peace.

  12. Contributions of positive psychology to peace: toward global well-being and resilience.

    PubMed

    Cohrs, J Christopher; Christie, Daniel J; White, Mathew P; Das, Chaitali

    2013-10-01

    In this article, we analyze the relationship between positive psychology and peace psychology. We discuss how positive emotions, engagement, meaning, personal well-being, and resilience may impact peace at different levels, ranging from the personal and interpersonal to community, national, and global peace. First, we argue that an individual's positive experiences, personal well-being, and personal resilience, as defined in current positive psychology, may in fact contribute to personal and interpersonal peace but can also entail detrimental consequences for other individuals, communities, and nations. Second, we describe how peace psychology contains traces of positive psychology, especially with its focus on the pursuit of social justice. Third, reviewing and extending the concept of community resilience, we outline directions for further conceptual and empirical work in positive psychology inspired by peace psychology. Such work would do well to transcend positive psychology's current bias toward individualism and nationalism and to conceptualize well-being and resilience at the level of the "global community." This extended "positive peace psychology" perspective would have important implications for our understanding of how to overcome oppression and work toward global peace. PMID:24128320

  13. Specification of a NAVSTAR Global Positioning System (GPS) receiver for a differential GPS ground system

    NASA Technical Reports Server (NTRS)

    Mccall, D. L.; Turner, R. N.

    1984-01-01

    One step towards the successful completion of a functional ground unit for the Differential Global Positioning System (DGPS) will be in choosing a currently available GPS receiver that will accurately measure the propagation times of the satellite signals and have the capability to be electrically interfaced with and controlled by a Digital Equipment Corporation (DEC) PDP-11/34A computer. The minimum requirements and characteristics of a NAVSTAR Global Positioning System (GPS) receiver are described. The specific technical specifications addressed include data accuracies and resolutions, receiver interface/external control, enclosure dimensions and mounting requirements, receiver operation, and environmental specifications.

  14. Non-dynamic decimeter tracking of earth satellites using the Global Positioning System

    NASA Technical Reports Server (NTRS)

    Yunck, T. P.; Wu, S. C.

    1986-01-01

    A technique is described for employing the Global Positioning System (GPS) to determine the position of a low earth orbiter with decimeter accuracy without the need for user dynamic models. A differential observing strategy is used requiring a GPS receiver on the user vehicle and a network of six ground receivers. The technique uses the continuous record of position change obtained from GPS carrier phase to smooth position measurements made with pseudo-range. The result is a computationally efficient technique that can deliver decimeter accuracy down to the lowest altitude orbits.

  15. Effects of Non-Differential Exposure Misclassification on False Conclusions in Hypothesis-Generating Studies

    PubMed Central

    Burstyn, Igor; Yang, Yunwen; Schnatter, A. Robert

    2014-01-01

    Despite the theoretical success of obviating the need for hypothesis-generating studies, they live on in epidemiological practice. Cole asserted that “… there is boundless number of hypotheses that could be generated, nearly all of them wrong” and urged us to focus on evaluating “credibility of hypothesis”. Adopting a Bayesian approach, we put this elegant logic into quantitative terms at the study planning stage for studies where the prior belief in the null hypothesis is high (i.e., “hypothesis-generating” studies). We consider not only type I and II errors (as is customary) but also the probabilities of false positive and negative results, taking into account typical imperfections in the data. We concentrate on a common source of imperfection in the data: non-differential misclassification of binary exposure classifier. In context of an unmatched case-control study, we demonstrate—both theoretically and via simulations—that although non-differential exposure misclassification is expected to attenuate real effect estimates, leading to the loss of ability to detect true effects, there is also a concurrent increase in false positives. Unfortunately, most investigators interpret their findings from such work as being biased towards the null rather than considering that they are no less likely to be false signals. The likelihood of false positives dwarfed the false negative rate under a wide range of studied settings. We suggest that instead of investing energy into understanding credibility of dubious hypotheses, applied disciplines such as epidemiology, should instead focus attention on understanding consequences of pursuing specific hypotheses, while accounting for the probability that the observed “statistically significant” association may be qualitatively spurious. PMID:25337942

  16. Using the Global Positioning System for Earth Orbiter and Deep Space Tracking

    NASA Technical Reports Server (NTRS)

    Lichten, Stephen M.

    1994-01-01

    The Global Positioning System (GPS) can play a major role in supporting orbit and trajectory determination for spacecraft in a wide range of applications, including low-Earth, high-Earth, and even deep space (interplanetary) tracking. This paper summarizes recent results demonstrating these unique and far-ranging applications of GPS.

  17. Global positioning system for general aviation: Joint FAA-NASA Seminar. [conferences

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Programs to examine and develop means to utilize the global positioning system (GPS) for civil aviation functions are described. User requirements in this regard are discussed, the development of technologies in the areas of antennas, receivers, and signal processors for the GPS are examined, and modifications to the GPS to fit operational and design criteria are evaluated.

  18. 76 FR 50808 - Airborne Supplemental Navigation Equipment Using the Global Positioning System (GPS)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-16

    ... standard for GPS sensors not augmented by satellite-based or ground- based systems (i.e., TSO-C129a Class B and Class C). The FAA has also published two GPS TSOs augmented by the satellite-based augmentation system (TSO-C145c, Airborne Navigation Sensors Using the Global Positioning System Augmented by...

  19. Portable device to assess dynamic accuracy of global positioning systems (GPS) receivers used in agricultural aircraft

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A device was designed to test the dynamic accuracy of Global Positioning System (GPS) receivers used in aerial vehicles. The system works by directing a sun-reflected light beam from the ground to the aircraft using mirrors. A photodetector is placed pointing downward from the aircraft and circuitry...

  20. Marine benefits from NASA's global differential system: sub-meter positioning, anywhere, anytime

    NASA Technical Reports Server (NTRS)

    Bar-Sever, Y.

    2000-01-01

    Precise real-time, onboard knowledge of a platform s state (position and velocity) is a critical compponent in many marine applications. This article describes a recent technology development that provides a breakthrough in this capability for platforms carrying a dual-frequency GPS receiver - seamless global coverage and roughly an order of magnitude improvement in accuracy compared to state-of-the-art.

  1. Miltipath measurements for land mobile satellite service using global positioning system signals

    NASA Technical Reports Server (NTRS)

    Lemmon, John J.

    1988-01-01

    A proposed multipath system for the land mobile satellite radio channel using the Global Positioning System (GPS) is presented. The measurement technique and equipment used to make multipath measurements on communications links are briefly described. The system configuration and performance specifications of the proposed measurement system are discussed.

  2. Determinants of physical and global functioning in adult HIV-positive heterosexual men.

    PubMed

    Shah, Krupa; McMahon, James M; Trabold, Nicole; Aidala, Angela A; Chen, Michael; Pouget, Enrique R; Simmons, Janie; Klostermann, Keith

    2015-01-01

    Little is known about the psychosocial factors that might impact the functioning ability of heterosexual men living with HIV. We examined positive and negative coping, social support, and HIV stigma as predictors of physical and global functioning in a cross-sectional sample of 317 HIV-infected adult heterosexual male patients recruited from clinical and social service agencies in New York City. Study participants were primarily minority and low income. Sixty-four percent were African-American, 55% were single, and 90% were 40 years of age or older. The majority had long-term HIV (LTHIV), with an average duration of 15 years since diagnosis. After controlling for participant characteristics, structural equation modeling analyses revealed that positive coping and social support had a significant positive direct effect on global functioning, while stigma had a significant negative direct effect on global functioning. The physical functioning model revealed that negative coping and HIV stigma had significant negative direct effects, whereas social support had a significant positive indirect effect. Age and duration of HIV diagnosis were not associated with physical and global functioning. In conclusion, we found that heterosexual men living with LTHIV who have ineffective coping, less social support, and greater stigma have reduced functioning ability. Study findings have implications for developing interventions aimed at increasing and retaining functioning ability with the end goal of improving successful aging in this population.

  3. Are the Autism and Positive Schizotypy Spectra Diametrically Opposed in Local versus Global Processing?

    ERIC Educational Resources Information Center

    Russell-Smith, Suzanna N.; Maybery, Murray T.; Bayliss, Donna M.

    2010-01-01

    Crespi and Badcock (2008) proposed that autism and psychosis represent two extremes on a cognitive spectrum with normality at its center. Their specific claim that autistic and positive schizophrenia traits contrastingly affect preference for local versus global processing was investigated by examining Embedded Figures Test performance in two…

  4. The Global Positioning System and Education in the 21st Century.

    ERIC Educational Resources Information Center

    Wikle, Thomas A.

    2000-01-01

    Students should have an understanding of basic Global Positioning System (GPS) principles as well as an awareness of how the technology will impact society in the future. Provides a brief overview of the evolution, principles, and applications of GPS together with suggested activities. (Contains 25 references.) (Author/WRM)

  5. Observations of geographically correlated orbit errors for TOPEX/Poseidon using the global positioning system

    NASA Technical Reports Server (NTRS)

    Christensen, E. J.; Haines, B. J.; Mccoll, K. C.; Nerem, R. S.

    1994-01-01

    We have compared Global Positioning System (GPS)-based dynamic and reduced-dynamic TOPEX/Poseidon orbits over three 10-day repeat cycles of the ground-track. The results suggest that the prelaunch joint gravity model (JGM-1) introduces geographically correlated errors (GCEs) which have a strong meridional dependence. The global distribution and magnitude of these GCEs are consistent with a prelaunch covariance analysis, with estimated and predicted global rms error statistics of 2.3 and 2.4 cm rms, respectively. Repeating the analysis with the post-launch joint gravity model (JGM-2) suggests that a portion of the meridional dependence observed in JGM-1 still remains, with global rms error of 1.2 cm.

  6. Position estimation and local mapping using omnidirectional images and global appearance descriptors.

    PubMed

    Berenguer, Yerai; Payá, Luis; Ballesta, Mónica; Reinoso, Oscar

    2015-01-01

    This work presents some methods to create local maps and to estimate the position of a mobile robot, using the global appearance of omnidirectional images. We use a robot that carries an omnidirectional vision system on it. Every omnidirectional image acquired by the robot is described only with one global appearance descriptor, based on the Radon transform. In the work presented in this paper, two different possibilities have been considered. In the first one, we assume the existence of a map previously built composed of omnidirectional images that have been captured from previously-known positions. The purpose in this case consists of estimating the nearest position of the map to the current position of the robot, making use of the visual information acquired by the robot from its current (unknown) position. In the second one, we assume that we have a model of the environment composed of omnidirectional images, but with no information about the location of where the images were acquired. The purpose in this case consists of building a local map and estimating the position of the robot within this map. Both methods are tested with different databases (including virtual and real images) taking into consideration the changes of the position of different objects in the environment, different lighting conditions and occlusions. The results show the effectiveness and the robustness of both methods. PMID:26501289

  7. Position Estimation and Local Mapping Using Omnidirectional Images and Global Appearance Descriptors

    PubMed Central

    Berenguer, Yerai; Payá, Luis; Ballesta, Mónica; Reinoso, Oscar

    2015-01-01

    This work presents some methods to create local maps and to estimate the position of a mobile robot, using the global appearance of omnidirectional images. We use a robot that carries an omnidirectional vision system on it. Every omnidirectional image acquired by the robot is described only with one global appearance descriptor, based on the Radon transform. In the work presented in this paper, two different possibilities have been considered. In the first one, we assume the existence of a map previously built composed of omnidirectional images that have been captured from previously-known positions. The purpose in this case consists of estimating the nearest position of the map to the current position of the robot, making use of the visual information acquired by the robot from its current (unknown) position. In the second one, we assume that we have a model of the environment composed of omnidirectional images, but with no information about the location of where the images were acquired. The purpose in this case consists of building a local map and estimating the position of the robot within this map. Both methods are tested with different databases (including virtual and real images) taking into consideration the changes of the position of different objects in the environment, different lighting conditions and occlusions. The results show the effectiveness and the robustness of both methods. PMID:26501289

  8. Initial results of radio occultation observations of Earth`s atmosphere using the Global Positioning System

    SciTech Connect

    Kursinski, E.R.; Hajj, G.A.; Bertiger, W.I.; Leroy, S.S.

    1996-02-23

    Recent radio occultation measurements using Global Positioning System satellite transmitters and an orbiting receiver have provided a globally distributed set of high-resolution atmospheric profiles, suggesting that the technique may may a significant contribution to global change and weather prediction programs. Biases in occultation temperatures relative to radiosonde and model data are about 1 kelvin or less in the tropics and are generally less than 0.5 kelvin at higher latitudes. Data quality is sufficient to quantify significant model errors in remote regions. Temperature profiles also reveal either an equatorial Rossby-gravity or an inertio-gravity wave. Such waves provide a fundamental source of momentum for the stratospheric circulation. 25 refs., 5 figs.

  9. An introduction to the global positioning system and some geological applications

    NASA Technical Reports Server (NTRS)

    Dixon, T. H.

    1991-01-01

    The fundamental principles of the global positioning system (GPS) are reviewed, with consideration given to geological and geophysical applications and related accuracy requirements. Recent improvements are emphasized which relate to areas such as equipment cost, limitations in the GPS satellite constellation, data analysis, uncertainties in satellite orbits and propagation delays, and problems in resolving carrier phase cycle ambiguities. Earthquake processes and near-fault crustal deformation monitoring have been facilitated by advances in GPS data acquisition and analysis. Horizontal positioning capability has been improved by new satellite constellation, better models, and global tracking networks. New classes of tectonic problems may now be studied through GPS, such as kinematic descriptions of crustal deformation and the measurement of relative plate motion at convergent boundaries. Continued improvements in the GPS are foreseen.

  10. Use of global positioning system (GPS) technology to map cross country pipelines

    SciTech Connect

    Barrett, J.P.

    1998-12-31

    Using Global Positioning System (GPS) to map pipelines could improve public safety, emergency response, protection of the environment, and reduce operational, regulatory, and asset integrity costs. Sub-meter to meter-level GPS accuracy can be a low-cost mapping technique to capture far more data than traditional meets-and-bound surveys. This paper will address some of the steps in determining what equipment, process, data dictionary, and data collection techniques would best fit the user`s application. Discussion will include the step-increase in costs for accuracy, equipment options, overall survey costs, data collection processes, and benefits of implementing a cost-effective mapping program using Global Positioning System (GPS) technology.

  11. Measuring precise sea level from a buoy using the Global Positioning System

    NASA Technical Reports Server (NTRS)

    Rocken, Christian; Kelecy, Thomas M.; Born, George H.; Young, Larry E.; Purcell, George H., Jr.; Wolf, Susan Kornreich

    1990-01-01

    The feasibility of using the Global Positioning System (GPS) for accurate sea surface positioning was examined. An experiment was conducted on the Scripps pier at La Jolla, California from December 13-15, 1989. A GPS-equipped buoy was deployed about 100 m off the pier. Two fixed reference GPS receivers, located on the pier and about 80 km away on Monument Peak, were used to estimate the relative position of the floater. Kinematic GPS processing software, developed at the National Geodetic Survey, and the Jet Propulsion Laboratory's GPS Infrared Processing System software were used to determine the floater position relative to land-fixing receivers. Calculations were made of sea level and ocean wave spectra from GPS measurements. It is found that the GPS sea level for the short 100 m baseline agrees with the PPT sea level at the 1 cm level and has an rms variation of 5 mm over a period of 4 hours.

  12. A Short Tutorial on Inertial Navigation System and Global Positioning System Integration

    NASA Technical Reports Server (NTRS)

    Smalling, Kyle M.; Eure, Kenneth W.

    2015-01-01

    The purpose of this document is to describe a simple method of integrating Inertial Navigation System (INS) information with Global Positioning System (GPS) information for an improved estimate of vehicle attitude and position. A simple two dimensional (2D) case is considered. The attitude estimates are derived from sensor data and used in the estimation of vehicle position and velocity through dead reckoning within the INS. The INS estimates are updated with GPS estimates using a Kalman filter. This tutorial is intended for the novice user with a focus on bringing the reader from raw sensor measurements to an integrated position and attitude estimate. An application is given using a remotely controlled ground vehicle operating in assumed 2D environment. The theory is developed first followed by an illustrative example.

  13. Physical Demands of Top-Class Soccer Friendly Matches in Relation to a Playing Position Using Global Positioning System Technology

    PubMed Central

    Mallo, Javier; Mena, Esteban; Nevado, Fabio; Paredes, Víctor

    2015-01-01

    The aim of this study was to examine the physical demands imposed on professional soccer players during 11-a-side friendly matches in relation to their playing position, using global positioning system (GPS) technology. One hundred and eleven match performances of a Spanish “La Liga” team during the 2010–11 and 2011–12 pre-seasons were selected for analysis. The activities of the players were monitored using GPS technology with a sampling frequency of 1 Hz. Total distance covered, distance in different speed categories, accelerations, and heart rate responses were analyzed in relation to five different playing positions: central defenders (n=23), full-backs (n=20), central midfielders (n=22), wide midfielders (n=26), and forwards (n=20). Distance covered during a match averaged 10.8 km, with wide and central midfielders covering the greatest total distance. Specifically, wide midfielders covered the greatest distances by very high-intensity running (>19.8 km·h-1) and central midfielders by jogging and running (7.2–19.7 km·h-1). On the other hand, central defenders covered the least total distance and at high intensity, although carried out more (p<0.05–0.01) accelerations than forwards, wide midfielders, and fullbacks. The work rate profile of the players obtained with the GPS was very similar to that obtained with semi-automatic image technologies. However, when comparing results from this study with data available in the literature, important differences were detected in the amount of distance covered by sprinting, which suggests that caution should be taken when comparing data obtained with the GPS with other motion analysis systems, especially regarding high-intensity activities. PMID:26557202

  14. Physical Demands of Top-Class Soccer Friendly Matches in Relation to a Playing Position Using Global Positioning System Technology.

    PubMed

    Mallo, Javier; Mena, Esteban; Nevado, Fabio; Paredes, Víctor

    2015-09-29

    The aim of this study was to examine the physical demands imposed on professional soccer players during 11-a-side friendly matches in relation to their playing position, using global positioning system (GPS) technology. One hundred and eleven match performances of a Spanish "La Liga" team during the 2010-11 and 2011-12 pre-seasons were selected for analysis. The activities of the players were monitored using GPS technology with a sampling frequency of 1 Hz. Total distance covered, distance in different speed categories, accelerations, and heart rate responses were analyzed in relation to five different playing positions: central defenders (n=23), full-backs (n=20), central midfielders (n=22), wide midfielders (n=26), and forwards (n=20). Distance covered during a match averaged 10.8 km, with wide and central midfielders covering the greatest total distance. Specifically, wide midfielders covered the greatest distances by very high-intensity running (>19.8 km·h-1) and central midfielders by jogging and running (7.2-19.7 km·h-1). On the other hand, central defenders covered the least total distance and at high intensity, although carried out more (p<0.05-0.01) accelerations than forwards, wide midfielders, and fullbacks. The work rate profile of the players obtained with the GPS was very similar to that obtained with semi-automatic image technologies. However, when comparing results from this study with data available in the literature, important differences were detected in the amount of distance covered by sprinting, which suggests that caution should be taken when comparing data obtained with the GPS with other motion analysis systems, especially regarding high-intensity activities.

  15. Physical Demands of Top-Class Soccer Friendly Matches in Relation to a Playing Position Using Global Positioning System Technology.

    PubMed

    Mallo, Javier; Mena, Esteban; Nevado, Fabio; Paredes, Víctor

    2015-09-29

    The aim of this study was to examine the physical demands imposed on professional soccer players during 11-a-side friendly matches in relation to their playing position, using global positioning system (GPS) technology. One hundred and eleven match performances of a Spanish "La Liga" team during the 2010-11 and 2011-12 pre-seasons were selected for analysis. The activities of the players were monitored using GPS technology with a sampling frequency of 1 Hz. Total distance covered, distance in different speed categories, accelerations, and heart rate responses were analyzed in relation to five different playing positions: central defenders (n=23), full-backs (n=20), central midfielders (n=22), wide midfielders (n=26), and forwards (n=20). Distance covered during a match averaged 10.8 km, with wide and central midfielders covering the greatest total distance. Specifically, wide midfielders covered the greatest distances by very high-intensity running (>19.8 km·h-1) and central midfielders by jogging and running (7.2-19.7 km·h-1). On the other hand, central defenders covered the least total distance and at high intensity, although carried out more (p<0.05-0.01) accelerations than forwards, wide midfielders, and fullbacks. The work rate profile of the players obtained with the GPS was very similar to that obtained with semi-automatic image technologies. However, when comparing results from this study with data available in the literature, important differences were detected in the amount of distance covered by sprinting, which suggests that caution should be taken when comparing data obtained with the GPS with other motion analysis systems, especially regarding high-intensity activities. PMID:26557202

  16. Determination of vertical deflections using the global positioning system and geodetic leveling

    SciTech Connect

    Solar, T.; Carlson, A.E. Jr.; Evans, A.G.

    1989-07-01

    The capabilities of the Global Positioning System (GPS) for accurately determining geodetic quantities are well established. Nevertheless, no comparison between deflections of the vertical as determined through GPS with leveling and values conventionally computer by astrogeodetic methods has yet been published. This investigation demonstrates that the accurate deflections of the vertical components ({eta}, {xi}) can be obtained independently of classical astronomic observations by combining geodetic leveling with satellite GOS positioning. The approach uses a radial configuration of baselines to determine the best (in a least square sense) values of ({eta}, {xi}) at the central station.

  17. Orbiter global positioning system design and Ku-band problems investigation, exhibit B, revision 1

    NASA Technical Reports Server (NTRS)

    Chie, C. M.; Braun, W. R.

    1981-01-01

    The LinCom effort in supporting the JSC study of the use of the Global Positioning System (GPS) on the space shuttle and in Ku-band problem investigation is documented. LinCom was tasked to evaluate system implementation, performance, and integration aspects of the shuttle GPS and to provide independent technical assessment of reports submitted to JSC regarding integration studies, system studies and navigation analyses.

  18. NAVSTAR global positioning system applicability to the National Oceanic Satellite System

    NASA Technical Reports Server (NTRS)

    Matchett, G. A.

    1980-01-01

    This report presents the results of a preliminary investigation into the potential for applying NAVSTAR Global Positioning System (GPS) user equipment to the spacecraft of the National Oceanic Satellite System (NOSS). Two widely different navigation goals for NOSS spacecraft are examined: one being moderate accuracy, real-time navigation utilizing the simplest of GPS receivers, and the other being precision vertical displacement measurement over limited arcs utilizing specialized GPS equipment, possibly with ground data processing.

  19. Global positioning system reobservations over the Eastern United States Strain Monitoring Network

    SciTech Connect

    Strange, W.E.

    1996-06-01

    In the period March--May, 1990, a 45 station geodetic network, originally established in November--December, 1987, was reobserved using global positioning system (GPS) technology. This network, known as the Eastern US Strain network, was established for the purpose of determining strain and deformation in the central and eastern US. This 1990 reobservation was the first of a series of reobservations scheduled to take place over a decade in order to place meaningful constraints on the small differential movements involved.

  20. Evolution of the Global Aurora During Positive IMP Bz and Varying IMP By Conditions

    NASA Technical Reports Server (NTRS)

    Cumnock, J. A.; Sharber, J. R.; Heelis. R. A.; Hairston, M. R.; Carven, J. D.

    1997-01-01

    The DE 1 imaging instrumentation provides a full view of the entire auroral oval every 12 min for several hours during each orbit. We examined five examples of global evolution of the aurora that occurred during the northern hemisphere winter of 1981-1982 when the z component of the interplanetary magnetic field was positive and the y component was changing sign. Evolution of an expanded auroral emission region into a theta aurora appears to require a change in the sign of By during northward interplanetary magnetic field (IMF). Theta aurora are formed both from expanded duskside emission regions (By changes from positive to negative) and dawnside emission regions (By changes from negative to positive), however the dawnside-originating and duskside-originating evolutions are not mirror images. The persistence of a theta aurora after its formation suggests that there may be no clear relationship between the theta aurora pattern and the instantaneous configuration of the IMF.

  1. Evaluating the Effect of Global Positioning System (GPS) Satellite Clock Error via GPS Simulation

    NASA Astrophysics Data System (ADS)

    Sathyamoorthy, Dinesh; Shafii, Shalini; Amin, Zainal Fitry M.; Jusoh, Asmariah; Zainun Ali, Siti

    2016-06-01

    This study is aimed at evaluating the effect of Global Positioning System (GPS) satellite clock error using GPS simulation. Two conditions of tests are used; Case 1: All the GPS satellites have clock errors within the normal range of 0 to 7 ns, corresponding to pseudorange error range of 0 to 2.1 m; Case 2: One GPS satellite suffers from critical failure, resulting in clock error in the pseudorange of up to 1 km. It is found that increase of GPS satellite clock error causes increase of average positional error due to increase of pseudorange error in the GPS satellite signals, which results in increasing error in the coordinates computed by the GPS receiver. Varying average positional error patterns are observed for the each of the readings. This is due to the GPS satellite constellation being dynamic, causing varying GPS satellite geometry over location and time, resulting in GPS accuracy being location / time dependent. For Case 1, in general, the highest average positional error values are observed for readings with the highest PDOP values, while the lowest average positional error values are observed for readings with the lowest PDOP values. For Case 2, no correlation is observed between the average positional error values and PDOP, indicating that the error generated is random.

  2. Quantification of Competitive Game Demands of NCAA Division I College Football Players Using Global Positioning Systems.

    PubMed

    Wellman, Aaron D; Coad, Sam C; Goulet, Grant C; McLellan, Christopher P

    2016-01-01

    The aim of the present study was to examine the competitive physiological movement demands of National Collegiate Athletic Association (NCAA) Division I college football players using portable global positioning system (GPS) technology during games and to examine positional groups within offensive and defensive teams, to determine if a player's physiological requirements during games are influenced by playing position. Thirty-three NCAA Division I Football Bowl Subdivision football players were monitored using GPS receivers with integrated accelerometers (GPSports) during 12 regular season games throughout the 2014 season. Individual data sets (n = 295) from players were divided into offensive and defensive teams and subsequent position groups. Movement profile characteristics, including total, low-intensity, moderate-intensity, high-intensity, and sprint running distances (m), sprint counts, and acceleration and deceleration efforts, were assessed during games. A one-way ANOVA and post-hoc Bonferroni statistical analysis were used to determine differences in movement profiles between each position group within offensive and defensive teams. For both offensive and defensive teams, significant (p ≤ 0.05) differences exist between positional groups for game physical performance requirements. The results of the present study identified that wide receivers and defensive backs completed significantly (p ≤ 0.05) greater total distance, high-intensity running, sprint distance, and high-intensity acceleration and deceleration efforts than their respective offensive and defensive positional groups. Data from the present study provide novel quantification of position-specific physical demands of college football games and support the use of position-specific training in the preparation of NCAA Division I college football players for competition.

  3. Observing Tropospheric Water Vapor by Radio Occultation using the Global Positioning System

    NASA Technical Reports Server (NTRS)

    Kursinski, E. R.; Hajj, G. A.; Hardy, K. R.; Romans, L. J.; Schofield, J. T.

    1995-01-01

    Given the importance of water vapor to weather, climate and hydrology, global humidity observations from satellites are critical. At low latitudes, radio occultation observations of Earth's atmosphere using the Global Positioning System (GPS) satellites allow water vapor profiles to be retrieved with accuracies of 10 to 20% below 6 to 7 km altitude and approx. 5% or better within the boundary layer. GPS observations provide a unique combination of accuracy, vertical resolution (less than or equal to 1 km) and insensitivity to cloud and aerosol particles that is well suited to observations of the lower troposphere. These characteristics combined with the inherent stability of radio occultation observations make it an excellent candidate for the measurement of long term trends.

  4. Precise tracking of remote sensing satellites with the Global Positioning System

    NASA Technical Reports Server (NTRS)

    Yunck, Thomas P.; Wu, Sien-Chong; Wu, Jiun-Tsong; Thornton, Catherine L.

    1990-01-01

    The Global Positioning System (GPS) can be applied in a number of ways to track remote sensing satellites at altitudes below 3000 km with accuracies of better than 10 cm. All techniques use a precise global network of GPS ground receivers operating in concert with a receiver aboard the user satellite, and all estimate the user orbit, GPS orbits, and selected ground locations simultaneously. The GPS orbit solutions are always dynamic, relying on the laws of motion, while the user orbit solution can range from purely dynamic to purely kinematic (geometric). Two variations show considerable promise. The first one features an optimal synthesis of dynamics and kinematics in the user solution, while the second introduces a novel gravity model adjustment technique to exploit data from repeat ground tracks. These techniques, to be demonstrated on the Topex/Poseidon mission in 1992, will offer subdecimeter tracking accuracy for dynamically unpredictable satellites down to the lowest orbital altitudes.

  5. Global attractivity of positive periodic solution to periodic Lotka-Volterra competition systems with pure delay

    NASA Astrophysics Data System (ADS)

    Tang, Xianhua; Cao, Daomin; Zou, Xingfu

    We consider a periodic Lotka-Volterra competition system without instantaneous negative feedbacks (i.e., pure-delay systems) x(t)=x(t)[r(t)-∑j=1na(t)x(t-τ(t))], i=1,2,…,n. We establish some 3/2-type criteria for global attractivity of a positive periodic solution of the system, which generalize the well-known Wright's 3/2 criteria for the autonomous delay logistic equation, and thereby, address the open problem proposed by both Kuang [Y. Kuang, Global stability in delayed nonautonomous Lotka-Volterra type systems without saturated equilibria, Differential Integral Equations 9 (1996) 557-567] and Teng [Z. Teng, Nonautonomous Lotka-Volterra systems with delays, J. Differential Equations 179 (2002) 538-561].

  6. MTV's "Staying Alive" global campaign promoted interpersonal communication about HIV and positive beliefs about HIV prevention.

    PubMed

    Geary, Cynthia Waszak; Burke, Holly McClain; Castelnau, Laure; Neupane, Shailes; Sall, Yacine Ba; Wong, Emily; Tucker, Heidi Toms

    2007-02-01

    In 2002 MTV launched a global multicomponent HIV prevention campaign, "Staying Alive," reaching over 166 countries worldwide. An evaluation of this campaign focused on three diverse sites: Kathmandu, Nepal; São Paulo, Brazil; and Dakar, Senegal. Data were collected before and after campaign implementation through population-based household surveys. Using linear regression techniques, our evaluation examined the effects of campaign exposure on interpersonal communication about HIV and the effects of campaign exposure and interpersonal communication on beliefs about HIV prevention. We found a consistent positive effect of exposure on interpersonal communication across all sites, though there were differences among sites with regard to whom the respondent talked about HIV. We also found a consistent positive effect of exposure on HIV prevention beliefs across sites when interpersonal communication was simultaneously entered into the model. Finally, in two sites we found a relationship between interpersonal communication and HIV prevention beliefs, controlling for exposure, though again, the effects differed by the type of person the communication was with. These similar findings in three diverse sites provide ecological validity of the findings that "Staying Alive" promoted interpersonal communication and influenced young people's beliefs about HIV prevention in a positive way, evidence for the potential of a global media campaign to have an impact on social norms.

  7. A demonstration of centimeter-level monitoring of polar motion with the Global Positioning System

    NASA Technical Reports Server (NTRS)

    Lindqwister, U. J.; Freedman, A. P.; Blewitt, G.

    1992-01-01

    Daily estimates of the Earth's pole position were obtained with the Global Positioning System (GPS) by using measurements obtained during the GPS IERS (International Earth Rotation Service) and Geodynamics (GIG'91) experiment from 22 Jan. to 13 Feb. 1991. Data from a globally distributed network consisting of 21 Rogue GPS receivers were chosen for the analysis. A comparison of the GPS polar motion series with nine 24-hour very long baseline interferometry (VLBI) estimates yielded agreement in the day-to-day pole position of about 1.5 cm for both X and Y polar motion. A similar comparison of GPS and satellite laser ranging (SLR) data showed agreement to about 1.0 cm. These preliminary results indicate that polar motion can be determined by GPS independent of, and at a level comparable to, that which is obtained from either VLBI or SLR. Furthermore, GPS can provide these data with a daily frequency that neither alternative technique can readily achieve. Thus, GPS promises to be a powerful tool for determining high-frequency platform parameter variation, essential for the ultraprecise spacecraft-tracking requirements of the coming years.

  8. MTV's "Staying Alive" global campaign promoted interpersonal communication about HIV and positive beliefs about HIV prevention.

    PubMed

    Geary, Cynthia Waszak; Burke, Holly McClain; Castelnau, Laure; Neupane, Shailes; Sall, Yacine Ba; Wong, Emily; Tucker, Heidi Toms

    2007-02-01

    In 2002 MTV launched a global multicomponent HIV prevention campaign, "Staying Alive," reaching over 166 countries worldwide. An evaluation of this campaign focused on three diverse sites: Kathmandu, Nepal; São Paulo, Brazil; and Dakar, Senegal. Data were collected before and after campaign implementation through population-based household surveys. Using linear regression techniques, our evaluation examined the effects of campaign exposure on interpersonal communication about HIV and the effects of campaign exposure and interpersonal communication on beliefs about HIV prevention. We found a consistent positive effect of exposure on interpersonal communication across all sites, though there were differences among sites with regard to whom the respondent talked about HIV. We also found a consistent positive effect of exposure on HIV prevention beliefs across sites when interpersonal communication was simultaneously entered into the model. Finally, in two sites we found a relationship between interpersonal communication and HIV prevention beliefs, controlling for exposure, though again, the effects differed by the type of person the communication was with. These similar findings in three diverse sites provide ecological validity of the findings that "Staying Alive" promoted interpersonal communication and influenced young people's beliefs about HIV prevention in a positive way, evidence for the potential of a global media campaign to have an impact on social norms. PMID:17411389

  9. Geometrically constrained kinematic global navigation satellite systems positioning: Implementation and performance

    NASA Astrophysics Data System (ADS)

    Asgari, Jamal; Mohammadloo, Tannaz H.; Amiri-Simkooei, Ali Reza

    2015-09-01

    GNSS kinematic techniques are capable of providing precise coordinates in extremely short observation time-span. These methods usually determine the coordinates of an unknown station with respect to a reference one. To enhance the precision, accuracy, reliability and integrity of the estimated unknown parameters, GNSS kinematic equations are to be augmented by possible constraints. Such constraints could be derived from the geometric relation of the receiver positions in motion. This contribution presents the formulation of the constrained kinematic global navigation satellite systems positioning. Constraints effectively restrict the definition domain of the unknown parameters from the three-dimensional space to a subspace defined by the equation of motion. To test the concept of the constrained kinematic positioning method, the equation of a circle is employed as a constraint. A device capable of moving on a circle was made and the observations from 11 positions on the circle were analyzed. Relative positioning was conducted by considering the center of the circle as the reference station. The equation of the receiver's motion was rewritten in the ECEF coordinates system. A special attention is drawn onto how a constraint is applied to kinematic positioning. Implementing the constraint in the positioning process provides much more precise results compared to the unconstrained case. This has been verified based on the results obtained from the covariance matrix of the estimated parameters and the empirical results using kinematic positioning samples as well. The theoretical standard deviations of the horizontal components are reduced by a factor ranging from 1.24 to 2.64. The improvement on the empirical standard deviation of the horizontal components ranges from 1.08 to 2.2.

  10. Measuring precise sea level from a buoy using the global positioning system

    SciTech Connect

    Rocken, C.; Kelecy, T.M.; Born, G.H. ); Young, L.E.; Purcell, G.H. Jr.; Wolf, S.K. )

    1990-11-01

    High-accuracy sea surface positioning is required for sea floor geodesy, satellite altimeter verification, and the study of sea level. An experiment to study the feasibility of using the Global Positioning System (GPS) for accurate sea surface positioning was conducted. A GPS-equipped buoy (floater) was deployed off the Scripps pier at La Jolla, California during December 13-15, 1989. Two reference GPS receivers were placed on land, one within {approximately}100 m of the floater, and the other about 80 km inland at the laser ranging site on Monument Peak. The position of the floater was determined relative to the land-fixed receivers using: (a) kinematic GPS processing software developed at the National Geodetic Survey (NGS), and (b) the Jet Propulsion Laboratory's GIPSY (GPS Inferred Positioning SYstem) software. Sea level and ocean wave spectra were calculated from GPPS measurements. These results were compared to measurements made with a NOAA tide gauge and a Paros{trademark} pressure transducer (PPT). GPS sea level for the short 100-m baseline agrees with the PPT sea level at the 1-cm level and has an rms variation of 5 mm over a period of 4 hours. Agreement between results with the two independent GPS analyses is on the order of a few millimeters. Processing of the longer Monument Peak - floater baseline is in progress and will require orbit adjustments and tropospheric modeling to obtain results comparable to the short baseline.

  11. Precise determination of earth's center of mass using measurements from the Global Positioning System

    NASA Technical Reports Server (NTRS)

    Vigue, Yvonne; Lichten, Stephen M.; Blewitt, Geoffrey; Heflin, Michael B.; Malla, Rajendra P.

    1992-01-01

    Global Positioning System (GPS) data from a worldwide geodetic experiment were collected during a 3-week period early in 1991. Geocentric station coordinates were estimated using the GPS data, thus defining a dynamically determined reference frame origin which should coincide with the earth center of mass, or geocenter. The 3-week GPS average geocenter estimates agree to 7-13 cm with geocenter estimates determined from satellite laser ranging, a well-established technique. The RMS of daily GPS geocenter estimates were 4 cm for x and y, and 30 cm for z.

  12. Vector Observation-Aided/Attitude-Rate Estimation Using Global Positioning System Signals

    NASA Technical Reports Server (NTRS)

    Oshman, Yaakov; Markley, F. Landis

    1997-01-01

    A sequential filtering algorithm is presented for attitude and attitude-rate estimation from Global Positioning System (GPS) differential carrier phase measurements. A third-order, minimal-parameter method for solving the attitude matrix kinematic equation is used to parameterize the filter's state, which renders the resulting estimator computationally efficient. Borrowing from tracking theory concepts, the angular acceleration is modeled as an exponentially autocorrelated stochastic process, thus avoiding the use of the uncertain spacecraft dynamic model. The new formulation facilitates the use of aiding vector observations in a unified filtering algorithm, which can enhance the method's robustness and accuracy. Numerical examples are used to demonstrate the performance of the method.

  13. Autonomous satellite orbit determination during the development phases of the global positioning system

    NASA Technical Reports Server (NTRS)

    Dunham, J. B.

    1980-01-01

    An onboard navigation system was developed to aid the design and evaluation of algorithms used in autonomous satellite navigation with Global Positioning System (GPS) data. The performance of the algorithms designed for a GPS Receiver/Processor Assembly (R/PA) intended for LANDSAT-D was investigated during the development phases of the GPS (four to six satellites in the constellation). This evaluation emphasized the effects on the orbit determination accuracy of the expected user clock errors, GPS satellite visibility, force model approximations, and state and covariance propagation approximations. Results are presented giving the sensitivity of orbit determination accuracy to these constraints.

  14. Toward an operational water vapor remote sensing system using the global positioning system

    SciTech Connect

    Gutman, S.I.; Chadwick, R.B.; Wolf, d.W.; Simon, A.; Van Hove, T.; Rocken, C.

    1995-04-01

    Water vapor is one of the most important constituents of the free atmosphere since it is the principal mechanism by which moisture and latent heat are transported and cause weather. Recent experiments have demonstrated that data from Global Positioning System (GPS) satellites can be used to monitor precipitable water vapor (PWV) with millimeter accuracy and sub-hourly temporal resolution. Major advantages of GPS-based systems include the following: they work under virtually all weather conditions; individual systems do not have to be calibrated; and, they are relatively inexpensive.

  15. Problems with studying wolf predation on small prey in summer via global positioning system collars

    USGS Publications Warehouse

    Palacios, Vicente; Mech, L. David

    2010-01-01

    We attempted to study predation on various-sized prey by a male and female wolf (Canis lupus) with global positioning system (GPS) collars programmed to acquire locations every 10 min in the Superior National Forest of Minnesota. During May to August 2007, we investigated 147 clusters of locations (31% of the total) and found evidence of predation on a white-tailed deer (Odocoileus virginianus) fawn and yearling, a beaver (Castor canadensis), ruffed grouse (Bonasa umbellus), and fisher (Martes pennanti) and scavenging on a road-killed deer and other carrion. However, we missed finding many prey items and discuss the problems associated with trying to conduct such a study.

  16. A study of autonomous satellite navigation methods using the global positioning satellite system

    NASA Technical Reports Server (NTRS)

    Tapley, B. D.

    1980-01-01

    Special orbit determination algorithms were developed to accommodate the size and speed limitations of on-board computer systems of the NAVSTAR Global Positioning System. The algorithms use square root sequential filtering methods. A new method for the time update of the square root covariance matrix was also developed. In addition, the time update method was compared with another square root convariance propagation method to determine relative performance characteristics. Comparisions were based on the results of computer simulations of the LANDSAT-D satellite processing pseudo range and pseudo range-rate measurements from the phase one GPS. A summary of the comparison results is presented.

  17. A Self-Tuning Kalman Filter for Autonomous Navigation Using the Global Positioning System (GPS)

    NASA Technical Reports Server (NTRS)

    Truong, Son H.

    1999-01-01

    Most navigation systems currently operated by NASA are ground-based, and require extensive support to produce accurate results. Recently developed systems that use Kalman filter and GPS (Global Positioning Systems) data for orbit determination greatly reduce dependency on ground support, and have potential to provide significant economies for NASA spacecraft navigation. These systems, however, still rely on manual tuning from analysts. A sophisticated neuro-fuzzy component fully integrated with the flight navigation system can perform the self-tuning capability for the Kalman filter and help the navigation system recover from estimation errors in real time.

  18. A New Centimeter-Level Real-Time Global Navigation and Positioning Capability with GPS

    NASA Technical Reports Server (NTRS)

    Bar-Sever, Yoaz

    2001-01-01

    NASA/JPL has developed a new, precise, global, GPS-based capability for real-time terrestrial and space platform navigation. It has been demonstrated on Earth's surface and is 10 times more accurate than other real-time GPS-based systems. The new system poses certain advantages for Earth science remote sensing, including: the onboard generation of science data products in real-time, sensor control and reduction of data transmission bandwidth, improved environmental forecasting, autonomous and intelligent platform control, operations cost savings, and technology transfer and commercial partnership opportunities. The system's measurement capabilities and applications, demonstrated orbit accuracies, and precision LEO and spacecraft positioning and timing are highlighted.

  19. A new model for yaw attitude of Global Positioning System satellites

    NASA Technical Reports Server (NTRS)

    Bar-Sever, Y. E.

    1995-01-01

    Proper modeling of the Global Positioning System (GPS) satellite yaw attitude is important in high-precision applications. A new model for the GPS satellite yaw attitude is introduced that constitutes a significant improvement over the previously available model in terms of efficiency, flexibility, and portability. The model is described in detail, and implementation issues, including the proper estimation strategy, are addressed. The performance of the new model is analyzed, and an error budget is presented. This is the first self-contained description of the GPS yaw attitude model.

  20. Improved treatment of global positioning system force parameters in precise orbit determination applications

    NASA Technical Reports Server (NTRS)

    Vigue, Y.; Lichten, S. M.; Muellerschoen, R. J.; Blewitt, G.; Heflin, M. B.

    1993-01-01

    Data collected from a worldwide 1992 experiment were processed at JPL to determine precise orbits for the satellites of the Global Positioning System (GPS). A filtering technique was tested to improve modeling of solar-radiation pressure force parameters for GPS satellites. The new approach improves orbit quality for eclipsing satellites by a factor of two, with typical results in the 25- to 50-cm range. The resultant GPS-based estimates for geocentric coordinates of the tracking sites, which include the three DSN sites, are accurate to 2 to 8 cm, roughly equivalent to 3 to 10 nrad of angular measure.

  1. Tracking of white-tailed deer migration by Global Positioning System

    USGS Publications Warehouse

    Nelson, M.E.; Mech, L.D.; Frame, P.F.

    2004-01-01

    Based on global positioning system (GPS) radiocollars in northeastern Minnesota, deer migrated 23-45 km in spring during 31-356 h, deviating a maximum 1.6-4.0 km perpendicular from a straight line of travel between their seasonal ranges. They migrated a minimum of 2.1-18.6 km/day over 11-56 h during 2-14 periods of travel. Minimum travel during 1-h intervals averaged 1.5 km/h. Deer paused 1-12 times, averaging 24 h/pause. Deer migrated similar distances in autumn with comparable rates and patterns of travel.

  2. Global Positioning System Time Transfer Receiver (GPS/TTR) prototype design and initial test evaluation

    NASA Technical Reports Server (NTRS)

    Oaks, J.; Frank, A.; Falvey, S.; Lister, M.; Buisson, J.; Wardrip, C.; Warren, H.

    1982-01-01

    Time transfer equipment and techniques used with the Navigation Technology Satellites were modified and extended for use with the Global Positioning System (GPS) satellites. A prototype receiver was built and field tested. The receiver uses the GPS L1 link at 1575 MHz with C/A code only to resolve a measured range to the satellite. A theoretical range is computed from the satellite ephemeris transmitted in the data message and the user's coordinates. Results of user offset from GPS time are obtained by differencing the measured and theoretical ranges and applying calibration corrections. Results of the first field test evaluation of the receiver are presented.

  3. Autonomous Navigation of the SSTI/Lewis Spacecraft Using the Global Positioning System (GPS)

    NASA Technical Reports Server (NTRS)

    Hart, R. C.; Long, A. C.; Lee, T.

    1997-01-01

    The National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) Flight Dynamics Division (FDD) is pursuing the application of Global Positioning System (GPS) technology to improve the accuracy and economy of spacecraft navigation. High-accuracy autonomous navigation algorithms are being flight qualified in conjunction with GSFC's GPS Attitude Determination Flyer (GADFLY) experiment on the Small Satellite Technology Initiative (SSTI) Lewis spacecraft, which is scheduled for launch in 1997. Preflight performance assessments indicate that these algorithms can provide a real-time total position accuracy of better than 10 meters (1 sigma) and velocity accuracy of better than 0.01 meter per second (1 sigma), with selective availability at typical levels. This accuracy is projected to improve to the 2-meter level if corrections to be provided by the GPS Wide Area Augmentation System (WAAS) are included.

  4. A Novel Method for Optimum Global Positioning System Satellite Selection Based on a Modified Genetic Algorithm.

    PubMed

    Song, Jiancai; Xue, Guixiang; Kang, Yanan

    2016-01-01

    In this paper, a novel method for selecting a navigation satellite subset for a global positioning system (GPS) based on a genetic algorithm is presented. This approach is based on minimizing the factors in the geometric dilution of precision (GDOP) using a modified genetic algorithm (MGA) with an elite conservation strategy, adaptive selection, adaptive mutation, and a hybrid genetic algorithm that can select a subset of the satellites represented by specific numbers in the interval (4 ∼ n) while maintaining position accuracy. A comprehensive simulation demonstrates that the MGA-based satellite selection method effectively selects the correct number of optimal satellite subsets using receiver autonomous integrity monitoring (RAIM) or fault detection and exclusion (FDE). This method is more adaptable and flexible for GPS receivers, particularly for those used in handset equipment and mobile phones. PMID:26943638

  5. Precise orbit determination for NASA's earth observing system using GPS (Global Positioning System)

    NASA Technical Reports Server (NTRS)

    Williams, B. G.

    1988-01-01

    An application of a precision orbit determination technique for NASA's Earth Observing System (EOS) using the Global Positioning System (GPS) is described. This technique allows the geometric information from measurements of GPS carrier phase and P-code pseudo-range to be exploited while minimizing requirements for precision dynamical modeling. The method combines geometric and dynamic information to determine the spacecraft trajectory; the weight on the dynamic information is controlled by adjusting fictitious spacecraft accelerations in three dimensions which are treated as first order exponentially time correlated stochastic processes. By varying the time correlation and uncertainty of the stochastic accelerations, the technique can range from purely geometric to purely dynamic. Performance estimates for this technique as applied to the orbit geometry planned for the EOS platforms indicate that decimeter accuracies for EOS orbit position may be obtainable. The sensitivity of the predicted orbit uncertainties to model errors for station locations, nongravitational platform accelerations, and Earth gravity is also presented.

  6. A Novel Method for Optimum Global Positioning System Satellite Selection Based on a Modified Genetic Algorithm

    PubMed Central

    Song, Jiancai; Xue, Guixiang; Kang, Yanan

    2016-01-01

    In this paper, a novel method for selecting a navigation satellite subset for a global positioning system (GPS) based on a genetic algorithm is presented. This approach is based on minimizing the factors in the geometric dilution of precision (GDOP) using a modified genetic algorithm (MGA) with an elite conservation strategy, adaptive selection, adaptive mutation, and a hybrid genetic algorithm that can select a subset of the satellites represented by specific numbers in the interval (4 ∼ n) while maintaining position accuracy. A comprehensive simulation demonstrates that the MGA-based satellite selection method effectively selects the correct number of optimal satellite subsets using receiver autonomous integrity monitoring (RAIM) or fault detection and exclusion (FDE). This method is more adaptable and flexible for GPS receivers, particularly for those used in handset equipment and mobile phones. PMID:26943638

  7. A Novel Method for Optimum Global Positioning System Satellite Selection Based on a Modified Genetic Algorithm.

    PubMed

    Song, Jiancai; Xue, Guixiang; Kang, Yanan

    2016-01-01

    In this paper, a novel method for selecting a navigation satellite subset for a global positioning system (GPS) based on a genetic algorithm is presented. This approach is based on minimizing the factors in the geometric dilution of precision (GDOP) using a modified genetic algorithm (MGA) with an elite conservation strategy, adaptive selection, adaptive mutation, and a hybrid genetic algorithm that can select a subset of the satellites represented by specific numbers in the interval (4 ∼ n) while maintaining position accuracy. A comprehensive simulation demonstrates that the MGA-based satellite selection method effectively selects the correct number of optimal satellite subsets using receiver autonomous integrity monitoring (RAIM) or fault detection and exclusion (FDE). This method is more adaptable and flexible for GPS receivers, particularly for those used in handset equipment and mobile phones.

  8. The positive Indian Ocean Dipole-like response in the tropical Indian Ocean to global warming

    NASA Astrophysics Data System (ADS)

    Luo, Yiyong; Lu, Jian; Liu, Fukai; Wan, Xiuquan

    2016-04-01

    Climate models project a positive Indian Ocean Dipole (pIOD)-like SST response in the tropical Indian Ocean to global warming. By employing the Community Earth System Model and applying an overriding technique to its ocean component (version 2 of the Parallel Ocean Program), this study investigates the similarities and differences of the formation mechanisms for the changes in the tropical Indian Ocean during the pIOD versus global warming. Results show that their formation processes and related seasonality are quite similar; in particular, wind-thermocline-SST feedback is the leading mechanism in producing the anomalous cooling over the eastern tropics in both cases. Some differences are also found, including the fact that the cooling effect of the vertical advection over the eastern tropical Indian Ocean is dominated by the anomalous vertical velocity during the pIOD but by the anomalous upper-ocean stratification under global warming. These findings are further examined through an analysis of the mixed layer heat budget.

  9. GPS meteorology - Remote sensing of atmospheric water vapor using the Global Positioning System

    NASA Technical Reports Server (NTRS)

    Bevis, Michael; Businger, Steven; Herring, Thomas A.; Rocken, Christian; Anthes, Richard A.; Ware, Randolph H.

    1992-01-01

    We present a new approach to remote sensing of water vapor based on the Global Positioning System (GPS). Geodesists and geophysicists have devised methods for estimating the extent to which signals propagating from GPS satellites to ground-based GPS receivers are delayed by atmospheric water vapor. This delay is parameterized in terms of a time-varying zenith wet delay (ZWD) which is retrieved by stochastic filtering of the GPS data. Given surface temperature and pressure readings at the GPS receiver, the retrieved ZWD can be transformed with very little additional uncertainty into an estimate of the integrated water vapor (IWV) overlying that receiver. Networks of continuously operating GPS receivers are being constructed by geodesists, geophysicists, and government and military agencies, in order to implement a wide range of positioning capabilities. These emerging GPS networks offer the possibility of observing the horizontal distribution of IWV or, equivalently, precipitate water with unprecedented coverage and a temporal resolution of the order of 10 min. These measurements could be utilized in operational weather forecasting and in fundamental research into atmospheric storm systems, the hydrologic cycle, atmospheric chemistry, and global climate change.

  10. Office of Space Flight standard spaceborne Global Positioning System user equipment project

    NASA Technical Reports Server (NTRS)

    Saunders, Penny E.

    1991-01-01

    The Global Positioning System (GPS) provides users autonomous, real-time navigation capability. A vehicle equipped with GPS user equipment can receive and process signals transmitted by a constellation of GPS satellites and derive from the resulting measurements the vehicle's position and velocity. Specified accuracies range from 16 to 76 meters and 0.1 to 1.0 meters/second for position and velocity, respectively. In a rendezvous and docking scenario, the use of a technique called relative GPS can provide range and range rate accuracies on the order of 1 meter and 0.01 meters/second, respectively. Relative GPS requires both vehicles to be equipped with GPS user equipment and a data communication link for transmission of GPS data and GPS satellite selection coordination information. Through coordinated satellite selection, GPS measurement errors common to both users are cancelled and improved relative position and velocity accuracies are achieved. The background, the design approach, the expected performance and capabilities, the development plan, and the project status are described. In addition, a description of relative GPS, the possible GPS hardware and software configurations, and its application to automated rendezvous and capture are presented.

  11. Ambiguity resolution in precise point positioning with hourly data for global single receiver

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaohong; Li, Pan; Guo, Fei

    2013-01-01

    Integer ambiguity resolution (IAR) can improve precise point positioning (PPP) performance significantly. IAR for PPP became a highlight topic in global positioning system (GPS) community in recent years. More and more researchers focus on this issue. Progress has been made in the latest years. In this paper, we aim at investigating and demonstrating the performance of a global zero-differenced (ZD) PPP IAR service for GPS users by providing routine ZD uncalibrated fractional offsets (UFOs) for wide-lane and narrow-lane. Data sets from all IGS stations collected on DOY 1, 100, 200 and 300 of 2010 are used to validate and demonstrate this global service. Static experiment results show that an accuracy better than 1 cm in horizontal and 1-2 cm in vertical could be achieved in ambiguity-fixed PPP solution with only hourly data. Compared with PPP float solution, an average improvement reaches 58.2% in east, 28.3% in north and 23.8% in vertical for all tested stations. Results of kinematic experiments show that the RMS of kinematic PPP solutions can be improved from 21.6, 16.6 and 37.7 mm to 12.2, 13.3 and 34.3 mm for the fixed solutions in the east, north and vertical components, respectively. Both static and kinematic experiments show that wide-lane and narrow-lane UFO products of all satellites can be generated and provided in a routine way accompanying satellite orbit and clock products for the PPP user anywhere around the world, to obtain accurate and reliable ambiguity-fixed PPP solutions.

  12. Mapping stream habitats with a global positioning system: Accuracy, precision, and comparison with traditional methods

    USGS Publications Warehouse

    Dauwalter, D.C.; Fisher, W.L.; Belt, K.C.

    2006-01-01

    We tested the precision and accuracy of the Trimble GeoXT??? global positioning system (GPS) handheld receiver on point and area features and compared estimates of stream habitat dimensions (e.g., lengths and areas of riffles and pools) that were made in three different Oklahoma streams using the GPS receiver and a tape measure. The precision of differentially corrected GPS (DGPS) points was not affected by the number of GPS position fixes (i.e., geographic location estimates) averaged per DGPS point. Horizontal error of points ranged from 0.03 to 2.77 m and did not differ with the number of position fixes per point. The error of area measurements ranged from 0.1% to 110.1% but decreased as the area increased. Again, error was independent of the number of position fixes averaged per polygon corner. The estimates of habitat lengths, widths, and areas did not differ when measured using two methods of data collection (GPS and a tape measure), nor did the differences among methods change at three stream sites with contrasting morphologies. Measuring features with a GPS receiver was up to 3.3 times faster on average than using a tape measure, although signal interference from high streambanks or overhanging vegetation occasionally limited satellite signal availability and prolonged measurements with a GPS receiver. There were also no differences in precision of habitat dimensions when mapped using a continuous versus a position fix average GPS data collection method. Despite there being some disadvantages to using the GPS in stream habitat studies, measuring stream habitats with a GPS resulted in spatially referenced data that allowed the assessment of relative habitat position and changes in habitats over time, and was often faster than using a tape measure. For most spatial scales of interest, the precision and accuracy of DGPS data are adequate and have logistical advantages when compared to traditional methods of measurement. ?? 2006 Springer Science+Business Media

  13. Match-play demands of elite youth Gaelic football using global positioning system tracking.

    PubMed

    Reilly, Brian; Akubat, Ibrahim; Lyons, Mark; Collins, D Kieran

    2015-04-01

    Global positioning systems (GPS) technology has made athlete-tracking a convenient and accepted technique to specify movement patterns and physical demands in sport. The purpose of this study was to examine positional demands of elite youth Gaelic football match-play using portable GPS technology to examine movement patterns and heart rates across match periods. Fifty-six elite youth male Gaelic footballers (age, 15 ± 0.66 years) fitted with portable 4-Hz GPS units were observed during 6 competitive matches (60 minutes). Data provided from the GPS unit included total distance, high-intensity (≥17·km·h(-1)) distance, sprint (≥22 km·h(-1)) distance, and total number of sprints. Heart rate was monitored continuously throughout the games. Players covered a mean distance of 5732 ± 1047 m, and the mean intensity of match-play was 85% of the peak heart rate. There was a significant (p = 0.028) drop in the total distance covered in the second half (2783 ± 599 m) compared with the first half (2948 ± 580 m). In particular, there is a noticeable drop in the distance covered in the third quarter of the game (after half-time), which has implications for re-warming up at the end of the half-time interval. There was a highly significant (p < .001) difference in the distance traveled across the 5 positional groups with midfielders covering the greatest total distance (6740 ± 384 m). The significant differences found with respect to positional groups support the implementation of individual, position-specific strength and conditioning programs.

  14. INTERIM GUIDANCE FOR DEVELOPING GLOBAL POSITIONING SYSTEM DATA COLLECTION STANDARD OPERATING PROCEDURES AND QUALITY ASSURANCE PROJECT PLANS

    EPA Science Inventory

    The United States Environmental Protection Agency Geospatial Quality Council developed this document to harmonize the process of collecting, editing, and exporting spatial data of known quality using the Global Positioning System (GPS). Each organizational entity may adopt this d...

  15. The Role of Trust and Interaction in Global Positioning System Related Accidents

    NASA Technical Reports Server (NTRS)

    Johnson, Chris W.; Shea, Christine; Holloway, C. Michael

    2008-01-01

    The Global Positioning System (GPS) uses a network of satellites to calculate the position of a receiver over time. This technology has revolutionized a wide range of safety-critical industries and leisure applications. These systems provide diverse benefits; supplementing the users existing navigation skills and reducing the uncertainty that often characterizes many route planning tasks. GPS applications can also help to reduce workload by automating tasks that would otherwise require finite cognitive and perceptual resources. However, the operation of these systems has been identified as a contributory factor in a range of recent accidents. Users often come to rely on GPS applications and, therefore, fail to notice when they develop faults or when errors occur in the other systems that use the data from these systems. Further accidents can stem from the over confidence that arises when users assume automated warnings will be issued when they stray from an intended route. Unless greater attention is paid to the role of trust and interaction in GPS applications then there is a danger that we will see an increasing number of these failures as positioning technologies become integral in the functioning of increasing numbers of applications.

  16. Global positioning system reoccupation of early triangulation sites - Tectonic deformation of the Southern Coast Ranges

    NASA Astrophysics Data System (ADS)

    Shen, Zheng-Kang; Jackson, David D.

    1993-06-01

    We study tectonic deformation in the Southern Coast Range, California. We use triangulation and astronomic azimuth data collected since 1875, trilateration since 1970, and global positioning system data collected from 1986 to 1987. Two modeling techniques have been used. An elastic block-fault model is applied to study the tectonic motion of the San Andreas Fault and the San Gregorio-Hosgri Fault. Station velocities are modeled to study regional deformations. Results show that the regional deformation is predominantly controlled by deep strike-slip motion along the San Andreas Fault, at a rate of 33 +/- 2 mm/yr. Deep slip along the San Gregorio-Hosgri Fault is about 0-4 mm/yr, assuming a locked suit to a depth of 20 km. Convergence normal to the San Andreas Fault in the Southern Coast Ranges is not greater than 0.02 microrad/yr.

  17. Sub-daily resolution of earth rotation variations with Global Positioning System measurements

    NASA Technical Reports Server (NTRS)

    Lichten, Stephen M.; Marcus, Steven L.; Dickey, Jean O.

    1992-01-01

    Data from a worldwide Global Positioning System (GPS) tracking experiment have been used to determine variations in earth rotation (UT1-UTC) over a time period of three weeks. Kalman filtering and smoothing enabled changes in UT1-UTC over intervals of 2 to 24 hrs to be detected with the GPS data. Internal consistency checks and comparisons with other solutions from very long baseline interferometry (VLBI) and satellite laser ranging (SLR) indicate that the GPS UT1-UTC estimates are accurate to about 2 cm. Comparison of GPS-estimated variations in UT1-UTC with 2-hr time resolution over 4 days with predicted variations computed from diurnal and semidiurnal oceanic tidal contributions strongly suggests that the observed periodic sub-daily variations of about 0.1 msec are largely of tidal origin.

  18. Constraints on Pacific plate kinematics and dynamics with global positioning system measurements

    NASA Technical Reports Server (NTRS)

    Dixon, T. H.; Golombek, M. P.; Thornton, C. L.

    1985-01-01

    A measurement program designed to investigate kinematic and dynamic aspects of plate tectonics in the Pacific region by means of satellite observations is proposed. Accuracy studies are summarized showing that for short baselines (less than 100 km), the measuring accuracy of global positioning system (GPS) receivers can be in the centimeter range. For longer baselines, uncertainty in the orbital ephemerides of the GPS satellites could be a major source of error. Simultaneous observations at widely (about 300 km) separated fiducial stations over the Pacific region, should permit an accuracy in the centimeter range for baselines of up to several thousand kilometers. The optimum performance level is based on the assumption of that fiducial baselines are known a priori to the centimeter range. An example fiducial network for a GPS study of the South Pacific region is described.

  19. Global positioning system reoccupation of early triangulation sites - Tectonic deformation of the Southern Coast Ranges

    NASA Technical Reports Server (NTRS)

    Shen, Zheng-Kang; Jackson, David D.

    1993-01-01

    We study tectonic deformation in the Southern Coast Range, California. We use triangulation and astronomic azimuth data collected since 1875, trilateration since 1970, and global positioning system data collected from 1986 to 1987. Two modeling techniques have been used. An elastic block-fault model is applied to study the tectonic motion of the San Andreas Fault and the San Gregorio-Hosgri Fault. Station velocities are modeled to study regional deformations. Results show that the regional deformation is predominantly controlled by deep strike-slip motion along the San Andreas Fault, at a rate of 33 +/- 2 mm/yr. Deep slip along the San Gregorio-Hosgri Fault is about 0-4 mm/yr, assuming a locked suit to a depth of 20 km. Convergence normal to the San Andreas Fault in the Southern Coast Ranges is not greater than 0.02 microrad/yr.

  20. Global positioning system surveying to monitor land subsidence in Sacramento Valley, California, USA

    USGS Publications Warehouse

    Ikehara, M.E.

    1994-01-01

    A subsidence research program began in 1985 to document the extent and magnitude of land subsidence in Sacramento Valley, California, an area of about 15 600 km2m, using Global Positioning System (GPS) surveying. In addition to periodic conventional spirit levelling, an examination was made of the changes in GPS-derived ellipsoidal height differences (summary differences) between pairs of adjacent bench marks in central Sacramento Valley from 1986 to 1989. The average rates of land subsidence in the southern Sacramento Valley for the past several decades were determined by comparing GPS-derived orthometric heights with historic published elevations. A maximum average rate of 0.053 m year-1 (0.90 m in 17 years) of subsidence has been measured. -Author

  1. Problems with studying wolf predation on small prey in summer via global positioning system collars

    USGS Publications Warehouse

    Palacios, V.; Mech, L.D.

    2011-01-01

    We attempted to study predation on various-sized prey by a male and female wolf (Canis lupus) with global positioning system (GPS) collars programmed to acquire locations every 10 min in the Superior National Forest of Minnesota. During May to August 2007, we investigated 147 clusters of locations (31% of the total) and found evidence of predation on a white-tailed deer (Odocoileus virginianus) fawn and yearling, a beaver (Castor canadensis), ruffed grouse (Bonasa umbellus), and fisher (Martes pennanti) and scavenging on a road-killed deer and other carrion. However, we missed finding many prey items and discuss the problems associated with trying to conduct such a study. ?? 2010 US Government.

  2. Integrating remote sensing, geographic information systems and global positioning system techniques with hydrological modeling

    NASA Astrophysics Data System (ADS)

    Thakur, Jay Krishna; Singh, Sudhir Kumar; Ekanthalu, Vicky Shettigondahalli

    2016-03-01

    Integration of remote sensing (RS), geographic information systems (GIS) and global positioning system (GPS) are emerging research areas in the field of groundwater hydrology, resource management, environmental monitoring and during emergency response. Recent advancements in the fields of RS, GIS, GPS and higher level of computation will help in providing and handling a range of data simultaneously in a time- and cost-efficient manner. This review paper deals with hydrological modeling, uses of remote sensing and GIS in hydrological modeling, models of integrations and their need and in last the conclusion. After dealing with these issues conceptually and technically, we can develop better methods and novel approaches to handle large data sets and in a better way to communicate information related with rapidly decreasing societal resources, i.e. groundwater.

  3. Efficient and Optimal Attitude Determination Using Recursive Global Positioning System Signal Operations

    NASA Technical Reports Server (NTRS)

    Crassidis, John L.; Lightsey, E. Glenn; Markley, F. Landis

    1998-01-01

    In this paper, a new and efficient algorithm is developed for attitude determination from Global Positioning System signals. The new algorithm is derived from a generalized nonlinear predictive filter for nonlinear systems. This uses a one time-step ahead approach to propagate a simple kinematics model for attitude determination. The advantages of the new algorithm over previously developed methods include: it provides optimal attitudes even for coplanar baseline configurations; it guarantees convergence even for poor initial conditions; it is a non-iterative algorithm; and it is computationally efficient. These advantages clearly make the new algorithm well suited to on-board applications. The performance of the new algorithm is tested on a dynamic hardware simulator. Results indicate that the new algorithm accurately estimates the attitude of a moving vehicle, and provides robust attitude estimates even when other methods, such as a linearized least-squares approach, fail due to poor initial starting conditions.

  4. Development of an accurate transmission line fault locator using the global positioning system satellites

    NASA Technical Reports Server (NTRS)

    Lee, Harry

    1994-01-01

    A highly accurate transmission line fault locator based on the traveling-wave principle was developed and successfully operated within B.C. Hydro. A transmission line fault produces a fast-risetime traveling wave at the fault point which propagates along the transmission line. This fault locator system consists of traveling wave detectors located at key substations which detect and time tag the leading edge of the fault-generated traveling wave as if passes through. A master station gathers the time-tagged information from the remote detectors and determines the location of the fault. Precise time is a key element to the success of this system. This fault locator system derives its timing from the Global Positioning System (GPS) satellites. System tests confirmed the accuracy of locating faults to within the design objective of +/-300 meters.

  5. Modular Software for Spacecraft Navigation Using the Global Positioning System (GPS)

    NASA Technical Reports Server (NTRS)

    Truong, S. H.; Hartman, K. R.; Weidow, D. A.; Berry, D. L.; Oza, D. H.; Long, A. C.; Joyce, E.; Steger, W. L.

    1996-01-01

    The Goddard Space Flight Center Flight Dynamics and Mission Operations Divisions have jointly investigated the feasibility of engineering modular Global Positioning SYSTEM (GPS) navigation software to support both real time flight and ground postprocessing configurations. The goals of this effort are to define standard GPS data interfaces and to engineer standard, reusable navigation software components that can be used to build a broad range of GPS navigation support applications. The paper discusses the GPS modular software (GMOD) system and operations concepts, major requirements, candidate software architecture, feasibility assessment and recommended software interface standards. In additon, ongoing efforts to broaden the scope of the initial study and to develop modular software to support autonomous navigation using GPS are addressed,

  6. Some tests of wet tropospheric calibration for the CASA Uno Global Positioning System experiment

    NASA Technical Reports Server (NTRS)

    Dixon, T. H.; Wolf, S. Kornreich

    1990-01-01

    Wet tropospheric path delay can be a major error source for Global Positioning System (GPS) geodetic experiments. Strategies for minimizing this error are investigted using data from CASA Uno, the first major GPS experiment in Central and South America, where wet path delays may be both high and variable. Wet path delay calibration using water vapor radiometers (WVRs) and residual delay estimation is compared with strategies where the entire wet path delay is estimated stochastically without prior calibration, using data from a 270-km test baseline in Costa Rica. Both approaches yield centimeter-level baseline repeatability and similar tropospheric estimates, suggesting that WVR calibration is not critical for obtaining high precision results with GPS in the CASA region.

  7. Demonstration of precise estimation of polar motion parameters with the global positioning system: Initial results

    NASA Technical Reports Server (NTRS)

    Lichten, S. M.

    1991-01-01

    Data from the Global Positioning System (GPS) were used to determine precise polar motion estimates. Conservatively calculated formal errors of the GPS least squares solution are approx. 10 cm. The GPS estimates agree with independently determined polar motion values from very long baseline interferometry (VLBI) at the 5 cm level. The data were obtained from a partial constellation of GPS satellites and from a sparse worldwide distribution of ground stations. The accuracy of the GPS estimates should continue to improve as more satellites and ground receivers become operational, and eventually a near real time GPS capability should be available. Because the GPS data are obtained and processed independently from the large radio antennas at the Deep Space Network (DSN), GPS estimation could provide very precise measurements of Earth orientation for calibration of deep space tracking data and could significantly relieve the ever growing burden on the DSN radio telescopes to provide Earth platform calibrations.

  8. TOPEX/POSEIDON operational orbit determination results using global positioning satellites

    NASA Technical Reports Server (NTRS)

    Guinn, J.; Jee, J.; Wolff, P.; Lagattuta, F.; Drain, T.; Sierra, V.

    1994-01-01

    Results of operational orbit determination, performed as part of the TOPEX/POSEIDON (T/P) Global Positioning System (GPS) demonstration experiment, are presented in this article. Elements of this experiment include the GPS satellite constellation, the GPS demonstration receiver on board T/P, six ground GPS receivers, the GPS Data Handling Facility, and the GPS Data Processing Facility (GDPF). Carrier phase and P-code pseudorange measurements from up to 24 GPS satellites to the seven GPS receivers are processed simultaneously with the GDPF software MIRAGE to produce orbit solutions of T/P and the GPS satellites. Daily solutions yield subdecimeter radial accuracies compared to other GPS, LASER, and DORIS precision orbit solutions.

  9. Spectral comparison of continuous Global Positioning System and strainmeter measurements of crustal deformation

    NASA Technical Reports Server (NTRS)

    Tralli, David M.

    1991-01-01

    Temporal power spectral density models of noise in continuous crustal deformation measurements obtained with the Global Positioning System (GPS) and high-quality strainmeters are compared. The crossover frequency at which GPS measurement noise is less than that of strainmeters is determined. Assuming GPS precision of 0.1 to 1 cm in horizontal components for baselines up to 100 km in length, local deformation monitoring with GPS may be preferable to strainmeters for observations of short-term deformation in under 6 months of continuous (at least daily) measurements. Short-period tropospheric path delays and multipath effects, which may obscure GPS-determined strain signals in local network measurements, also are discussed.

  10. Present-day crustal deformation in China constrained by global positioning system measurements.

    PubMed

    Wang, Q; Zhang, P Z; Freymueller, J T; Bilham, R; Larson, K M; Lai, X; You, X; Niu, Z; Wu, J; Li, Y; Liu, J; Yang, Z; Chen, Q

    2001-10-19

    Global Positioning System (GPS) measurements in China indicate that crustal shortening accommodates most of India's penetration into Eurasia. Deformation within the Tibetan Plateau and its margins, the Himalaya, the Altyn Tagh, and the Qilian Shan, absorbs more than 90% of the relative motion between the Indian and Eurasian plates. Internal shortening of the Tibetan plateau itself accounts for more than one-third of the total convergence. However, the Tibetan plateau south of the Kunlun and Ganzi-Mani faults is moving eastward relative to both India and Eurasia. This movement is accommodated through rotation of material around the eastern Syntaxis. The North China and South China blocks, east of the Tibetan Plateau, move coherently east-southeastward at rates of 2 to 8 millimeters per year and 6 to 11 millimeters per year, respectively, with respect to the stable Eurasia. PMID:11641493

  11. Space Shuttle Global Positioning System (GPS) testing at NASA Johnson Space Center

    NASA Technical Reports Server (NTRS)

    Pawlowski, J. F.; Quinn, M.

    1982-01-01

    The present investigation is concerned with the significance of the use of the Global Positioning System (GPS) for the Space Shuttle. On the basis of a study regarding the use of the GPS on the Space Shuttle, it was decided that such a system would greatly benefit Space Shuttle navigation. Studies with GPS user equipment were, therefore, conducted to obtain data and information which would provide a base for the formulation and the further refinement of NASA requirements with respect to the type of set the Shuttle would need. Attention is given to orbit determination, satellite numbers, background information concerning the GPS, the currently available GPS sets, the conducted studies, Shuttle sonic boom recording sites, tests performed with the aid of the Kuiper airborne observatory, and questions regarding the test applicability to Shuttle GPS.

  12. The limits of direct satellite tracking with the Global Positioning System (GPS)

    NASA Technical Reports Server (NTRS)

    Bertiger, W. I.; Yunck, T. P.

    1988-01-01

    Recent advances in high precision differential Global Positioning System-based satellite tracking can be applied to the more conventional direct tracking of low earth satellites. To properly evaluate the limiting accuracy of direct GPS-based tracking, it is necessary to account for the correlations between the a-priori errors in GPS states, Y-bias, and solar pressure parameters. These can be obtained by careful analysis of the GPS orbit determination process. The analysis indicates that sub-meter accuracy can be readily achieved for a user above 1000 km altitude, even when the user solution is obtained with data taken 12 hours after the data used in the GPS orbit solutions.

  13. Three Years of Global Positioning System Experience on International Space Station

    NASA Technical Reports Server (NTRS)

    Gomez, Susan

    2005-01-01

    The International Space Station global positioning systems (GPS) receiver was activated in April 2002. Since that time, numerous software anomalies surfaced that had to be worked around. Some of the software problems required waivers, such as the time function, while others required extensive operator intervention, such as numerous power cycles. Eventually, enough anomalies surfaced that the three pieces of code included in the GPS unit have been re-written and the GPS units were upgraded. The technical aspects of the problems are discussed, as well as the underlying causes that led to the delivery of a product that has had numerous problems. The technical aspects of the problems included physical phenomena that were not well understood, such as the affect that the ionosphere would have on the GPS measurements. The underlying causes were traced to inappropriate use of legacy software, changing requirements, inadequate software processes, unrealistic schedules, incorrect contract type, and unclear ownership responsibilities.

  14. Three Years of Global Positioning System Experience on International Space Station

    NASA Technical Reports Server (NTRS)

    Gomez, Susan

    2006-01-01

    The International Space Station global positioning system (GPS) receiver was activated in April 2002. Since that time, numerous software anomalies surfaced that had to be worked around. Some of the software problems required waivers, such as the time function, while others required extensive operator intervention, such as numerous power cycles. Eventually enough anomalies surfaced that the three pieces of code included in the GPS unit have been re-written and the GPS units upgraded. The technical aspects of the problems are discussed, as well as the underlying causes that led to the delivery of a product that has had so many problems. The technical aspects of the problems included physical phenomena that were not well understood, such as the affect that the ionosphere would have on the GPS measurements. The underlying causes were traced to inappropriate use of legacy software, changing requirements, inadequate software processes, unrealistic schedules, incorrect contract type, and unclear ownership responsibilities..

  15. Global systems for mobile position tracking using Kalman and Lainiotis filters.

    PubMed

    Assimakis, Nicholas; Adam, Maria

    2014-01-01

    We present two time invariant models for Global Systems for Mobile (GSM) position tracking, which describe the movement in x-axis and y-axis simultaneously or separately. We present the time invariant filters as well as the steady state filters: the classical Kalman filter and Lainiotis Filter and the Join Kalman Lainiotis Filter, which consists of the parallel usage of the two classical filters. Various implementations are proposed and compared with respect to their behavior and to their computational burden: all time invariant and steady state filters have the same behavior using both proposed models but have different computational burden. Finally, we propose a Finite Impulse Response (FIR) implementation of the Steady State Kalman, and Lainiotis filters, which does not require previous estimations but requires a well-defined set of previous measurements. PMID:24883349

  16. Relative motions of the Australian, Pacific and Antarctic plates estimated by the Global Positioning System

    NASA Technical Reports Server (NTRS)

    Larson, Kristine M.; Freymueller, Jeff

    1995-01-01

    Global Positioning System (GPS) measurements spanning approximately 3 years have been used to determine velocities for 7 sites on the Australian, Pacific and Antarctic plates. The site velocities agree with both plate model predictions and other space geodetic techniques. We find no evidence for internal deformation of the interior of the Australian plate. Wellington, New Zealand, located in the Australian-Pacific plate boundary zone, moves 20 +/- 5 mm/yr west-southwest relative to the Australian plate. Its velocity lies midway between the predicted velocities of the two plates. Relative Euler vectors for the Australia-Antarctica and Pacific-Antarctica plates agree within one standard deviation with the NUVEL-1A predictions.

  17. Regularized estimation of vertical total electron content from Global Positioning System data

    NASA Astrophysics Data System (ADS)

    Arikan, F.; Erol, C. B.; Arikan, O.

    2003-12-01

    A novel regularization technique which can combine signals from all Global Positioning System (GPS) satellites for a given instant and a given receiver is developed to estimate the vertical total electron content (VTEC) values for the 24-hour period without missing any important features in the temporal domain. The algorithm is based on the minimization of a cost function which also includes a high pass penalty filter. Optional weighting function and sliding window median filter are added to enrich the processing and smoothing of the data. The developed regularized estimation algorithm is applied to GPS data for various locations for the solar maximum week of 23-28 April 2001. The parameter set that is required by the estimation algorithm is chosen optimally using appropriate error functions. This robust and optimum parameter set can be used for all latitudes and for both quiet and disturbed days. It is observed that the estimated TEC values are in general accordance with the TEC estimates from other global ionospheric maps, especially for quiet days and midlatitudes. Owing to its 30 s time resolution, the regularized VTEC estimates from the developed algorithm are very successful in representation and tracking of sudden temporal variations of the ionosphere, especially for high latitudes and during ionospheric disturbances.

  18. Use of global positioning system measurements to determine geocentric coordinates and variations in Earth orientation

    NASA Technical Reports Server (NTRS)

    Malla, R. P.; Wu, S.-C.; Lichten, S. M.

    1993-01-01

    Geocentric tracking station coordinates and short-period Earth-orientation variations can be measured with Global Positioning System (GPS) measurements. Unless calibrated, geocentric coordinate errors and changes in Earth orientation can lead to significant deep-space tracking errors. Ground-based GPS estimates of daily and subdaily changes in Earth orientation presently show centimeter-level precision. Comparison between GPS-estimated Earth-rotation variations, which are the differences between Universal Time 1 and Universal Coordinated Time (UT1-UTC), and those calculated from ocean tide models suggests that observed subdaily variations in Earth rotation are dominated by oceanic tidal effects. Preliminary GPS estimates for the geocenter location (from a 3-week experiment) agree with independent satellite laser-ranging estimates to better than 10 cm. Covariance analysis predicts that temporal resolution of GPS estimates for Earth orientation and geocenter improves significantly when data collected from low Earth-orbiting satellites as well as from ground sites are combined. The low Earth GPS tracking data enhance the accuracy and resolution for measuring high-frequency global geodynamical signals over time scales of less than 1 day.

  19. Plate Motion and Crustal Deformation Estimated with Geodetic Data from the Global Positioning System

    NASA Technical Reports Server (NTRS)

    Argus, Donald F.; Heflin, Michael B.

    1995-01-01

    We use geodetic data taken over four years with the Global Positioning System (GPS) to estimate: (1) motion between six major plates and (2) motion relative to these plates of ten sites in plate boundary zones. The degree of consistency between geodetic velocities and rigid plates requires the (one-dimensional) standard errors in horizontal velocities to be approx. 2 mm/yr. Each of the 15 angular velocities describing motion between plate pairs that we estimate with GPS differs insignificantly from the corresponding angular velocity in global plate motion model NUVEL-1A, which averages motion over the past 3 m.y. The motion of the Pacific plate relative to both the Eurasian and North American plates is observed to be faster than predicted by NUVEL-1A, supporting the inference from Very Long B ase- line Interferometry (VLBI) that motion of the Pacific plate has speed up over the past few m.y. The Eurasia-North America pole of rotation is estimated to be north of NUVEL-1A, consistent with the independent hypothesis that the pole has recently migrated northward across northeast Asia to near the Lena River delta. Victoria, which lies above the main thrust at the Cascadia subduction zone, moves relative to the interior of the overriding plate at 30% of the velocity of the subducting plate, reinforcing the conclusion that the thrust there is locked beneath the continental shelf and slope.

  20. Global Positioning System Use in the Community to Evaluate Improvements in Walking After Revascularization

    PubMed Central

    Gernigon, Marie; Le Faucheur, Alexis; Fradin, Dominique; Noury-Desvaux, Bénédicte; Landron, Cédric; Mahe, Guillaume; Abraham, Pierre

    2015-01-01

    Abstract Revascularization aims at improving walking ability in patients with arterial claudication. The highest measured distance between 2 stops (highest-MDCW), the average walking speed (average-WSCW), and the average stop duration (average-DSCW) can be measured by global positioning system, but their evolution after revascularization is unknown. We included 251 peripheral artery diseased patients with self-reported limiting claudication. The patients performed a 1-hour stroll, recorded by a global positioning system receiver. Patients (n = 172) with confirmed limitation (highest-MDCW <2000m) at inclusion were reevaluated after 6 months. Patients revascularized during the follow-up period were compared with reference patients (ie, with unchanged lifestyle medical or surgical status). Other patients (lost to follow-up or treatment change) were excluded (n = 89). We studied 44 revascularized and 39 reference patients. Changes in highest-MDCW (+442 vs. +13 m) and average-WSCW (+0.3 vs. −0.2 km h−1) were greater in revascularized than in reference patients (both P < 0.01). In contrast, no significant difference in average-DSCW changes was found between the groups. Among the revascularized patients, 13 (29.5%) had a change in average-WSCW, but not in highest-MDCW, greater than the mean + 1 standard deviation of the change observed for reference patients. Revascularization may improve highest-MDCW and/or average-WSCW. This first report of changes in community walking ability in revascularized patients suggests that, beyond measuring walking distances, average-WSCW measurement is essential to monitor these changes. Applicability to other surgical populations remains to be evaluated. Registration: http://www.clinicaltrials.gov/ct2/show/NCT01141361 PMID:25950694

  1. Helicopter approach capability using the differential global positioning system. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Kaufmann, David N.

    1993-01-01

    The results of flight tests to determine the feasibility of using the Global Positioning System (GPS) in the differential mode (DGPS) to provide high accuracy, precision navigation, and guidance for helicopter approaches to landing are presented. The airborne DGPS receiver and associated equipment is installed in a NASA UH-60 Black Hawk helicopter. The ground-based DGPS reference receiver is located at a surveyed test site and is equipped with a real-time VHF data link to transmit correction information to the airborne DGPS receiver. The corrected airborne DGPS information, together with the preset approach geometry, is used to calculate guidance commands which are sent to the aircraft's approach guidance instruments. The use of DGPS derived guidance for helicopter approaches to landing is evaluated by comparing the DGPS data with the laser tracker truth data. Both standard (3 deg) and steep (6 deg and 9 deg) glideslope straight-in approaches were flown. DGPS positioning accuracy based on a time history analysis of the entire approach was 0.2 m (mean) +/- 1.8 m (2 sigma) laterally and -2.0 m (mean) +/- 3.5 m (2 sigma) vertically for 3 deg glideslope approaches, -0.1 m (mean) +/- 1.5 m (2 sigma) laterally and -1.1 m (mean) +/- 3.5 m (2 sigma) vertically for 6 deg glideslope approaches and 0.2 m (mean) +/- 1.3 m (2 sigma) laterally and -1.0 m (mean) +/- 2.8 m (2 sigma) vertically for 9 deg glideslope approaches. DGPS positioning accuracy at the 200 ft decision height (DH) on a standard 3 deg slideslope approach was 0.3 m (mean) +/- 1.5 m (2 sigma) laterally and -2.3 m (mean) +/- 1.6 m (2 sigma) vertically. These errors indicate that the helicopter position based on DGPS guidance satisfies the International Civil Aviation Organization (ICAO) Category 1 (CAT 1) lateral and vertical navigational accuracy requirements.

  2. Detecting and characterizing genomic signatures of positive selection in global populations.

    PubMed

    Liu, Xuanyao; Ong, Rick Twee-Hee; Pillai, Esakimuthu Nisha; Elzein, Abier M; Small, Kerrin S; Clark, Taane G; Kwiatkowski, Dominic P; Teo, Yik-Ying

    2013-06-01

    Natural selection is a significant force that shapes the architecture of the human genome and introduces diversity across global populations. The question of whether advantageous mutations have arisen in the human genome as a result of single or multiple mutation events remains unanswered except for the fact that there exist a handful of genes such as those that confer lactase persistence, affect skin pigmentation, or cause sickle cell anemia. We have developed a long-range-haplotype method for identifying genomic signatures of positive selection to complement existing methods, such as the integrated haplotype score (iHS) or cross-population extended haplotype homozygosity (XP-EHH), for locating signals across the entire allele frequency spectrum. Our method also locates the founder haplotypes that carry the advantageous variants and infers their corresponding population frequencies. This presents an opportunity to systematically interrogate the whole human genome whether a selection signal shared across different populations is the consequence of a single mutation process followed subsequently by gene flow between populations or of convergent evolution due to the occurrence of multiple independent mutation events either at the same variant or within the same gene. The application of our method to data from 14 populations across the world revealed that positive-selection events tend to cluster in populations of the same ancestry. Comparing the founder haplotypes for events that are present across different populations revealed that convergent evolution is a rare occurrence and that the majority of shared signals stem from the same evolutionary event. PMID:23731540

  3. Global positioning system and associated technologies in animal behaviour and ecological research

    PubMed Central

    Tomkiewicz, Stanley M.; Fuller, Mark R.; Kie, John G.; Bates, Kirk K.

    2010-01-01

    Biologists can equip animals with global positioning system (GPS) technology to obtain accurate (less than or equal to 30 m) locations that can be combined with sensor data to study animal behaviour and ecology. We provide the background of GPS techniques that have been used to gather data for wildlife studies. We review how GPS has been integrated into functional systems with data storage, data transfer, power supplies, packaging and sensor technologies to collect temperature, activity, proximity and mortality data from terrestrial species and birds. GPS ‘rapid fixing’ technologies combined with sensors provide location, dive frequency and duration profiles, and underwater acoustic information for the study of marine species. We examine how these rapid fixing technologies may be applied to terrestrial and avian applications. We discuss positional data quality and the capability for high-frequency sampling associated with GPS locations. We present alternatives for storing and retrieving data by using dataloggers (biologging), radio-frequency download systems (e.g. very high frequency, spread spectrum), integration of GPS with other satellite systems (e.g. Argos, Globalstar) and potential new data recovery technologies (e.g. network nodes). GPS is one component among many rapidly evolving technologies. Therefore, we recommend that users and suppliers interact to ensure the availability of appropriate equipment to meet animal research objectives. PMID:20566494

  4. Detecting and characterizing genomic signatures of positive selection in global populations.

    PubMed

    Liu, Xuanyao; Ong, Rick Twee-Hee; Pillai, Esakimuthu Nisha; Elzein, Abier M; Small, Kerrin S; Clark, Taane G; Kwiatkowski, Dominic P; Teo, Yik-Ying

    2013-06-01

    Natural selection is a significant force that shapes the architecture of the human genome and introduces diversity across global populations. The question of whether advantageous mutations have arisen in the human genome as a result of single or multiple mutation events remains unanswered except for the fact that there exist a handful of genes such as those that confer lactase persistence, affect skin pigmentation, or cause sickle cell anemia. We have developed a long-range-haplotype method for identifying genomic signatures of positive selection to complement existing methods, such as the integrated haplotype score (iHS) or cross-population extended haplotype homozygosity (XP-EHH), for locating signals across the entire allele frequency spectrum. Our method also locates the founder haplotypes that carry the advantageous variants and infers their corresponding population frequencies. This presents an opportunity to systematically interrogate the whole human genome whether a selection signal shared across different populations is the consequence of a single mutation process followed subsequently by gene flow between populations or of convergent evolution due to the occurrence of multiple independent mutation events either at the same variant or within the same gene. The application of our method to data from 14 populations across the world revealed that positive-selection events tend to cluster in populations of the same ancestry. Comparing the founder haplotypes for events that are present across different populations revealed that convergent evolution is a rare occurrence and that the majority of shared signals stem from the same evolutionary event.

  5. Detecting and Characterizing Genomic Signatures of Positive Selection in Global Populations

    PubMed Central

    Liu, Xuanyao; Ong, Rick Twee-Hee; Pillai, Esakimuthu Nisha; Elzein, Abier M.; Small, Kerrin S.; Clark, Taane G.; Kwiatkowski, Dominic P.; Teo, Yik-Ying

    2013-01-01

    Natural selection is a significant force that shapes the architecture of the human genome and introduces diversity across global populations. The question of whether advantageous mutations have arisen in the human genome as a result of single or multiple mutation events remains unanswered except for the fact that there exist a handful of genes such as those that confer lactase persistence, affect skin pigmentation, or cause sickle cell anemia. We have developed a long-range-haplotype method for identifying genomic signatures of positive selection to complement existing methods, such as the integrated haplotype score (iHS) or cross-population extended haplotype homozygosity (XP-EHH), for locating signals across the entire allele frequency spectrum. Our method also locates the founder haplotypes that carry the advantageous variants and infers their corresponding population frequencies. This presents an opportunity to systematically interrogate the whole human genome whether a selection signal shared across different populations is the consequence of a single mutation process followed subsequently by gene flow between populations or of convergent evolution due to the occurrence of multiple independent mutation events either at the same variant or within the same gene. The application of our method to data from 14 populations across the world revealed that positive-selection events tend to cluster in populations of the same ancestry. Comparing the founder haplotypes for events that are present across different populations revealed that convergent evolution is a rare occurrence and that the majority of shared signals stem from the same evolutionary event. PMID:23731540

  6. Integration of differential global positioning system with ultrawideband synthetic aperture radar for forward imaging

    NASA Astrophysics Data System (ADS)

    Wong, David C.; Bui, Khang; Nguyen, Lam H.; Smith, Gregory; Ton, Tuan T.

    2003-09-01

    The U.S. Army Research Laboratory (ARL), as part of a customer and mission-funded exploratory development program, has been evaluating low-frequency, ultra-wideband (UWB) imaging radar for forward imaging to support the Army's vision for increased mobility and survivability of unmanned ground vehicle missions. As part of the program to improve the radar system and imaging capability, ARL has incorporated a differential global positioning system (DGPS) for motion compensation into the radar system. The use of DGPS can greatly increase positional accuracy, thereby allowing us to improve our ability to focus better images for the detection of small targets such as plastic mines and other concealed objects buried underground. The ability of UWB radar technology to detect concealed objects could provide an important obstacle avoidance capability for robotic vehicles, which would improve the speed and maneuverability of these vehicles and consequently increase the survivability of the U.S. forces. This paper details the integration and discusses the significance of integrating a DGPS into the radar system for forward imaging. It also compares the difference between DGPS and the motion compensation data collected by the use of the original theodolite-based system.

  7. The Validity and Reliability of Global Positioning Systems in Team Sport: A Brief Review.

    PubMed

    Scott, Macfarlane T U; Scott, Tannath J; Kelly, Vincent G

    2016-05-01

    The use of global positioning systems (GPS) has increased dramatically over the last decade. Using signals from orbiting satellites, the GPS receiver calculates the exact position of the device and the speed at which the device is moving. Within team sports GPS devices are used to quantify the external load experienced by an athlete, allowing coaches to better manage trainings loads and potentially identify athletes who are overreaching or overtraining. This review aims to collate all studies that have tested either (or both) the validity or reliability of GPS devices in a team sport setting, with a particular focus on (a) measurements of distance, speed, velocities, and accelerations across all sampling rates and (b) accelerometers, player/body load and impacts in accelerometer-integrated GPS devices. A comprehensive search of the online libraries identified 22 articles that fit search criteria. The literature suggests that all GPS units, regardless of sampling rate, are capable of tracking athlete's distance during team sport movements with adequate intraunit reliability. One Hertz and 5Hz GPS units have limitations in their reporting of distance during high-intensity running, velocity measures, and short linear running (particularly those involving changes of direction), although these limitations seem to be overcome during measures recorded during team sport movements. Ten Hertz GPS devices seem the most valid and reliable to date across linear and team sport simulated running, overcoming many limitations of earlier models, whereas the increase to 15Hz GPS devices have had no additional benefit. PMID:26439776

  8. Simulation and analysis of differential global positioning system for civil helicopter operations

    NASA Technical Reports Server (NTRS)

    Denaro, R. P.; Cabak, A. R.

    1983-01-01

    A Differential Global Positioning System (DGPS) computer simulation was developed, to provide a versatile tool for assessing DGPS referenced civil helicopter navigation. The civil helicopter community will probably be an early user of the GPS capability because of the unique mission requirements which include offshore exploration and low altitude transport into remote areas not currently served by ground based Navaids. The Monte Carlo simulation provided a sufficiently high fidelity dynamic motion and propagation environment to enable accurate comparisons of alternative differential GPS implementations and navigation filter tradeoffs. The analyst has provided the capability to adjust most aspects of the system, the helicopter flight profile, the receiver Kalman filter, and the signal propagation environment to assess differential GPS performance and parameter sensitivities. Preliminary analysis was conducted to evaluate alternative implementations of the differential navigation algorithm in both the position and measurement domain. Results are presented to show that significant performance gains are achieved when compared with conventional GPS but that differences due to DGPS implementation techniques were small. System performance was relatively insensitive to the update rates of the error correction information.

  9. Global positioning system and associated technologies in animal behaviour and ecological research

    USGS Publications Warehouse

    Tomkiewicz, Stanley M.; Fuller, Mark R.; Kie, John G.; Bates, Kirk K.

    2010-01-01

    Biologists can equip animals with global positioning system (GPS) technology to obtain accurate (less than or equal to 30 m) locations that can be combined with sensor data to study animal behaviour and ecology. We provide the background of GPS techniques that have been used to gather data for wildlife studies. We review how GPS has been integrated into functional systems with data storage, data transfer, power supplies, packaging and sensor technologies to collect temperature, activity, proximity and mortality data from terrestrial species and birds. GPS 'rapid fixing' technologies combined with sensors provide location, dive frequency and duration profiles, and underwater acoustic information for the study of marine species. We examine how these rapid fixing technologies may be applied to terrestrial and avian applications. We discuss positional data quality and the capability for high-frequency sampling associated with GPS locations. We present alternatives for storing and retrieving data by using dataloggers (biologging), radio-frequency download systems (e.g. very high frequency, spread spectrum), integration of GPS with other satellite systems (e.g. Argos, Globalstar) and potential new data recovery technologies (e.g. network nodes). GPS is one component among many rapidly evolving technologies. Therefore, we recommend that users and suppliers interact to ensure the availability of appropriate equipment to meet animal research objectives.

  10. Time determination for spacecraft users of the Navstar Global Positioning System /GPS/

    NASA Technical Reports Server (NTRS)

    Grenchik, T. J.; Fang, B. T.

    1977-01-01

    Global Positioning System (GPS) navigation is performed by time measurements. A description is presented of a two body model of spacecraft motion. Orbit determination is the process of inferring the position, velocity, and clock offset of the user from measurements made of the user motion in the Newtonian coordinate system. To illustrate the effect of clock errors and the accuracy with which the user spacecraft time and orbit may be determined, a low-earth-orbit spacecraft (Seasat) as tracked by six Phase I GPS space vehicles is considered. The obtained results indicate that in the absence of unmodeled dynamic parameter errors clock biases may be determined to the nanosecond level. There is, however, a high correlation between the clock bias and the uncertainty in the gravitational parameter GM, i.e., the product of the universal gravitational constant and the total mass of the earth. It is, therefore, not possible to determine clock bias to better than 25 nanosecond accuracy in the presence of a gravitational error of one part per million.

  11. The Validity and Reliability of Global Positioning Systems in Team Sport: A Brief Review.

    PubMed

    Scott, Macfarlane T U; Scott, Tannath J; Kelly, Vincent G

    2016-05-01

    The use of global positioning systems (GPS) has increased dramatically over the last decade. Using signals from orbiting satellites, the GPS receiver calculates the exact position of the device and the speed at which the device is moving. Within team sports GPS devices are used to quantify the external load experienced by an athlete, allowing coaches to better manage trainings loads and potentially identify athletes who are overreaching or overtraining. This review aims to collate all studies that have tested either (or both) the validity or reliability of GPS devices in a team sport setting, with a particular focus on (a) measurements of distance, speed, velocities, and accelerations across all sampling rates and (b) accelerometers, player/body load and impacts in accelerometer-integrated GPS devices. A comprehensive search of the online libraries identified 22 articles that fit search criteria. The literature suggests that all GPS units, regardless of sampling rate, are capable of tracking athlete's distance during team sport movements with adequate intraunit reliability. One Hertz and 5Hz GPS units have limitations in their reporting of distance during high-intensity running, velocity measures, and short linear running (particularly those involving changes of direction), although these limitations seem to be overcome during measures recorded during team sport movements. Ten Hertz GPS devices seem the most valid and reliable to date across linear and team sport simulated running, overcoming many limitations of earlier models, whereas the increase to 15Hz GPS devices have had no additional benefit.

  12. Maintenance of the Geodetic Reference Frame in the Global Positioning System

    NASA Astrophysics Data System (ADS)

    Oria, A.; Brodsky, B. L.; Labrecque, J.; Miller, J. J.; Moreau, M.; Pearlman, M.; Nelson, R.

    2007-12-01

    In the Global Positioning System (GPS) measurements of the satellite coordinates and the underlying World Geodetic System 1984 (WGS 84) reference frame are derived from observables such as pseudorandom noise (PRN) signals, and carrier phase, which are referenced to on-board atomic clocks. Systematic errors exist in both the estimated satellite coordinates and the reference frame. The reference frame utilizes external inputs in the form of International Terrestrial Reference Frame (ITRF) coordinates and constrains the results to be compatible with the ITRF coordinates for a set of global reference stations. The ITRF is, in turn, obtained from the combined analysis of GPS, Satellite Laser Ranging (SLR), Very Long Baseline Interferometry (VLBI), and Doppler Orbitography and Radio-positioning Integrated by Satellite (DORIS) data. The current realization of the reference frame could be described as circular in that an independent method of external verification is currently not available. To ensure the continued successful operation of the GPS it is necessary to have the capability of analyzing systematic errors by an independent means from current radiometric observables and data from foreign sources. In practice, accuracy of the standards used for measurement should be better than the expected, required operational measurement accuracy by a factor of ten to ensure that the desired requirement is met. Currently, the accuracy of both the ITRF and the WGS 84 is estimated to be on the order of 1 to 2 parts per billion, leading to expected drifts of 0.6 to 1.2 cm per year. The experience of the last three decades has indicated an approximate improvement by a factor of ten per decade. Therefore, while current accuracy of the ITRF and WGS 84 reference frames marginally meets civilian and military requirements, it is very likely that, within the lifetime of GPS III, the accuracy of the reference frames will be unable to meet the anticipated requirements. This report examines

  13. Analysis of the positive ionospheric response to a moderate geomagnetic storm using a global numerical model

    NASA Astrophysics Data System (ADS)

    Namgaladze, A. A.; Förster, M.; Yurik, R. Y.

    2000-04-01

    Current theories of F-layer storms are discussed using numerical simulations with the Upper Atmosphere Model, a global self-consistent, time dependent numerical model of the thermosphere-ionosphere-plasmasphere-magnetosphere system including electrodynamical coupling effects. A case study of a moderate geomagnetic storm at low solar activity during the northern winter solstice exemplifies the complex storm phenomena. The study focuses on positive ionospheric storm effects in relation to thermospheric disturbances in general and thermospheric composition changes in particular. It investigates the dynamical effects of both neutral meridional winds and electric fields caused by the disturbance dynamo effect. The penetration of short-time electric fields of magnetospheric origin during storm intensification phases is shown for the first time in this model study. Comparisons of the calculated thermospheric composition changes with satellite observations of AE-C and ESRO-4 during storm time show a good agreement. The empirical MSISE90 model, however, is less consistent with the simulations. It does not show the equatorward propagation of the disturbances and predicts that they have a gentler latitudinal gradient. Both theoretical and experimental data reveal that although the ratio of [O]/[N2] at high latitudes decreases significantly during the magnetic storm compared with the quiet time level, at mid to low latitudes it does not increase (at fixed altitudes) above the quiet reference level. Meanwhile, the ionospheric storm is positive there. We conclude that the positive phase of the ionospheric storm is mainly due to uplifting of ionospheric F2-region plasma at mid latitudes and its equatorward movement at low latitudes along geomagnetic field lines caused by large-scale neutral wind circulation and the passage of travelling atmospheric disturbances (TADs). The calculated zonal electric field disturbances also help to create the positive ionospheric disturbances both

  14. Detecting grizzly bear use of ungulate carcasses using global positioning system telemetry and activity data.

    PubMed

    Ebinger, Michael R; Haroldson, Mark A; van Manen, Frank T; Costello, Cecily M; Bjornlie, Daniel D; Thompson, Daniel J; Gunther, Kerry A; Fortin, Jennifer K; Teisberg, Justin E; Pils, Shannon R; White, P J; Cain, Steven L; Cross, Paul C

    2016-07-01

    Global positioning system (GPS) wildlife collars have revolutionized wildlife research. Studies of predation by free-ranging carnivores have particularly benefited from the application of location clustering algorithms to determine when and where predation events occur. These studies have changed our understanding of large carnivore behavior, but the gains have concentrated on obligate carnivores. Facultative carnivores, such as grizzly/brown bears (Ursus arctos), exhibit a variety of behaviors that can lead to the formation of GPS clusters. We combined clustering techniques with field site investigations of grizzly bear GPS locations (n = 732 site investigations; 2004-2011) to produce 174 GPS clusters where documented behavior was partitioned into five classes (large-biomass carcass, small-biomass carcass, old carcass, non-carcass activity, and resting). We used multinomial logistic regression to predict the probability of clusters belonging to each class. Two cross-validation methods-leaving out individual clusters, or leaving out individual bears-showed that correct prediction of bear visitation to large-biomass carcasses was 78-88 %, whereas the false-positive rate was 18-24 %. As a case study, we applied our predictive model to a GPS data set of 266 bear-years in the Greater Yellowstone Ecosystem (2002-2011) and examined trends in carcass visitation during fall hyperphagia (September-October). We identified 1997 spatial GPS clusters, of which 347 were predicted to be large-biomass carcasses. We used the clustered data to develop a carcass visitation index, which varied annually, but more than doubled during the study period. Our study demonstrates the effectiveness and utility of identifying GPS clusters associated with carcass visitation by a facultative carnivore. PMID:26971522

  15. Detecting grizzly bear use of ungulate carcasses using global positioning system telemetry and activity data.

    PubMed

    Ebinger, Michael R; Haroldson, Mark A; van Manen, Frank T; Costello, Cecily M; Bjornlie, Daniel D; Thompson, Daniel J; Gunther, Kerry A; Fortin, Jennifer K; Teisberg, Justin E; Pils, Shannon R; White, P J; Cain, Steven L; Cross, Paul C

    2016-07-01

    Global positioning system (GPS) wildlife collars have revolutionized wildlife research. Studies of predation by free-ranging carnivores have particularly benefited from the application of location clustering algorithms to determine when and where predation events occur. These studies have changed our understanding of large carnivore behavior, but the gains have concentrated on obligate carnivores. Facultative carnivores, such as grizzly/brown bears (Ursus arctos), exhibit a variety of behaviors that can lead to the formation of GPS clusters. We combined clustering techniques with field site investigations of grizzly bear GPS locations (n = 732 site investigations; 2004-2011) to produce 174 GPS clusters where documented behavior was partitioned into five classes (large-biomass carcass, small-biomass carcass, old carcass, non-carcass activity, and resting). We used multinomial logistic regression to predict the probability of clusters belonging to each class. Two cross-validation methods-leaving out individual clusters, or leaving out individual bears-showed that correct prediction of bear visitation to large-biomass carcasses was 78-88 %, whereas the false-positive rate was 18-24 %. As a case study, we applied our predictive model to a GPS data set of 266 bear-years in the Greater Yellowstone Ecosystem (2002-2011) and examined trends in carcass visitation during fall hyperphagia (September-October). We identified 1997 spatial GPS clusters, of which 347 were predicted to be large-biomass carcasses. We used the clustered data to develop a carcass visitation index, which varied annually, but more than doubled during the study period. Our study demonstrates the effectiveness and utility of identifying GPS clusters associated with carcass visitation by a facultative carnivore.

  16. Detecting grizzly bear use of ungulate carcasses using global positioning system telemetry and activity data

    USGS Publications Warehouse

    Ebinger, Michael R.; Haroldson, Mark A.; van Manen, Frank T.; Costello, Cecily M; Bjornlie, Daniel D; Thompson, Daniel J.; Gunther, Kerry A.; Fortin, Jennifer K.; Teisberg, Justin E.; Pils, Shannon R; White, P J; Cain, Steven L; Cross, Paul C.

    2016-01-01

    Global positioning system (GPS) wildlife collars have revolutionized wildlife research. Studies of predation by free-ranging carnivores have particularly benefited from the application of location clustering algorithms to determine when and where predation events occur. These studies have changed our understanding of large carnivore behavior, but the gains have concentrated on obligate carnivores. Facultative carnivores, such as grizzly/brown bears (Ursus arctos), exhibit a variety of behaviors that can lead to the formation of GPS clusters. We combined clustering techniques with field site investigations of grizzly bear GPS locations (n = 732 site investigations; 2004–2011) to produce 174 GPS clusters where documented behavior was partitioned into five classes (large-biomass carcass, small-biomass carcass, old carcass, non-carcass activity, and resting). We used multinomial logistic regression to predict the probability of clusters belonging to each class. Two cross-validation methods—leaving out individual clusters, or leaving out individual bears—showed that correct prediction of bear visitation to large-biomass carcasses was 78–88%, whereas the false-positive rate was 18–24%. As a case study, we applied our predictive model to a GPS data set of 266 bear-years in the Greater Yellowstone Ecosystem (2002–2011) and examined trends in carcass visitation during fall hyperphagia (September–October). We identified 1997 spatial GPS clusters, of which 347 were predicted to be large-biomass carcasses. We used the clustered data to develop a carcass visitation index, which varied annually, but more than doubled during the study period. Our study demonstrates the effectiveness and utility of identifying GPS clusters associated with carcass visitation by a facultative carnivore.

  17. Global Positioning System measurements of strain accumulation across the Imperial Valley, California - 1986-1989

    NASA Technical Reports Server (NTRS)

    Larsen, Shawn; Reilinger, Robert

    1992-01-01

    The Global Positioning System (GPS) data collected in southern California from 1986 to 1989 indicate considerable strain accumulation across the Imperial Valley. Displacements are computed at 29 stations in and near the valley from 1986 to 1988, and at 11 sites from 1988 to 1989. The earlier measurements indicate 5.9 =/- 1.0 cm/yr right-lateral differential velocity across the valley, although the data are heavily influenced by the 1987 Superstition Hills earthquake sequence. Some measurements, especially the east-trending displacements, are suspects for large errors. The 1988 to 1989 GPS displacements are best modeled by 5.2 =/- 0.9 cm/yr of valley crossing deformation, but rates calculated from conventional geodetic measurements (3.4 to 4.3 cm/yr) fit the data nearly as well. There is evidence from GPS and Very Long Base Interferometry (VLBI) observations that the present slip rate along the southern San Andreas fault is smaller than the long-term geologic estimate, suggesting a lower earthquake potential than is currently assumed. Correspondingly, a higher earthquake potential is indicated for the San Jacinto fault. The Imperial Valley GPS sites form part of a 183 station network in southern California and northern Baja California, which spans a cross-section of the North American-Pacific plate boundary.

  18. Current and planned use of the Navstar Global Positioning System by NASA

    NASA Technical Reports Server (NTRS)

    Theiss, Harold L.

    1993-01-01

    NASA was quick to realize the potential that the Global Positioning System (GPS) had to offer for its many diverse vehicles, experiments and platforms. Soon after the first Block 1 GPS satellites were launched, NASA began to use the tremendous capabilities that they had to offer. Even with a partial GPS constellation in place, important results have been obtained about the shape, orientation and rotation of the earth and calibration of the ionosphere and troposphere. These calibrations enhance geophysical science and facilitate the navigation of interplanetary spacecraft. Some very important results have been obtained in the continuing NASA program for aircraft terminal area operations. Currently, a large amount of activity is being concentrated on real time kinematic carrier phase tracking which has the potential to revolutionize aircraft navigation. This year marks the launch of the first GPS receiver equipped earth-orbiting NASA spacecraft: the Extreme Ultraviolet Explorer and the Ocean Topography Experiment (TOPEX/Poseidon). This paper describes a cross section of GPS-based research at NASA.

  19. Using global positioning systems to study health-related mobility and participation.

    PubMed

    Brusilovskiy, Eugene; Klein, Louis A; Salzer, Mark S

    2016-07-01

    Community participation, as indicated by mobility and engagement in socially meaningful activities, is a central component of health based on the International Classification of Health, Functioning, and Disease (WHO, 2001). Global positioning systems (GPS) technology is emerging as a tool for tracking mobility and participation in health and disability-related research. This paper fills a gap in the literature and provides a thorough description of a method that can be used to generate a number of different variables related to the constructs of mobility and participation from GPS data. Here, these variables are generated with the help of ST-DBSCAN, a spatiotemporal data mining algorithm. The variables include the number of unique destinations, activity space area, distance traveled, time in transit, and time at destinations. Data obtained from five individuals with psychiatric disabilities who carried GPS-enabled cell phones for two weeks are presented. Within- and across- individual variability on these constructs was observed. Given the feasibility of gathering data with GPS, larger scale studies of mobility and participation employing this method are warranted.

  20. The use of global positioning systems in promoting safer walking for people with dementia.

    PubMed

    McKinstry, Brian; Sheikh, Aziz

    2013-07-01

    There are about 5 million people in Europe who have dementia, approximately half of whom need daily care. A common reason why dementia sufferers are admitted to long-term care is because of "wandering", i.e. leaving home without informing a carer, thereby potentially putting themselves at risk. Common methods of managing wandering include locking doors or alerting carers when a door is opened. A new method of managing wandering is by using electronic location devices. These depend on the satellite-based global positioning system (GPS). People can wear a location device in the form of a watch or pendant, or carry it like a mobile phone. This offers affected individuals the possibility of safe walking, with the reassurance that they can be found quickly if lost. However, it is not known how effective this method is and its use raises questions about safety and individual civil liberties. GPS location is a potentially useful method of managing wandering in dementia and there is considerable pressure on caregivers from commercial organisations to adopt the technique. Research is therefore required to determine which people are best suited for such devices, how effective they are in practice and what effect they have on important outcomes.

  1. Potential of Global Positioning System (GPS) to measure frequencies of oscillations of engineering structures

    NASA Astrophysics Data System (ADS)

    Psimoulis, Panos; Pytharouli, Stella; Karambalis, Dimitris; Stiros, Stathis

    2008-12-01

    Global Positioning System (GPS) has been successfully used to measure displacements of oscillating flexible civil engineering structures such as long suspension bridges and high-rise buildings, and to derive their modal frequencies, usually up to 1 Hz, but there is evidence that these limits can be exceeded using high frequency GPS receivers. Based on systematic experiments in computer controlled oscillations with one- and three-degrees of freedom we investigated the potential of GPS, first to record higher oscillation frequencies, at least up to 4 Hz at the minimum resolution level of this instrument for kinematic applications (⩾5 mm), and second, to identify more than one dominant frequency. Data were processed using least squares-based spectral analysis and wavelet techniques which permit to analyze entire time series, even those of too short duration or those characterized by gaps, in both the frequency and the time domain. The ability of GPS to accurately measure frequencies of oscillations of relatively rigid (modal frequencies 1-4 Hz) civil engineering structures is demonstrated in the cases of two bridges. The outcome of this study is that GPS is suitable for the identification of dynamic characteristics of even relatively rigid (modal frequencies up to 4 Hz) civil engineering structures excited by various loads (wind, traffic, earthquakes, etc.) if displacements are above the uncertainty level of the method (⩾5 mm). Structural health monitoring of a wide range of structures appears therefore a promising field of application of GPS.

  2. Tracking the movement of Hawaiian volcanoes; Global Positioning System (GPS) measurement

    USGS Publications Warehouse

    Dvorak, J.J.

    1992-01-01

    At some well-studied volcanoes, surface movements of at least several centimeters take place out to distances of about 10 km from the summit of the volcano. Widespread deformation of this type is relatively easy to monitor, because the necessary survey stations can be placed at favorable sites some distance from the summit of the volcano. Examples of deformation of this type include Kilauea and Mauna Loa in Hawaii, Krafla in Iceland, Long Valley in California, Camp Flegrei in Italy, and Sakurajima in Japan. In contrast, surface movement at some other volcanoes, usually volcanoes with steep slopes, is restricted to places within about 1 km of their summits. Examples of this class of volcanoes include Mount St. Helens in Washington, Etna in Italy, and Tangkuban Parahu in Indonesia. Local movement on remote, rugged volcanoes of this type is difficult to observe using conventional methods of measuring ground movement, which generally require a clear line-of-sight between points of interest. However, a revolutionary new technique, called the Global Positional System (GPS), provides a very efficient, alternative method of making such measurements. GPS, which uses satellites and ground-based receivers to accurately record slight crustal movements, is rapidly becoming the method of choice to measure deformation at volcanoes. 

  3. Testing global positioning system telemetry to study wolf predation on deer fawns

    USGS Publications Warehouse

    Demma, D.J.; Barber-Meyer, S. M.; Mech, L.D.

    2007-01-01

    We conducted a pilot study to test the usefulness of Global Positioning System (GPS) collars for investigating wolf (Canis lupus) predation on white-tailed deer (Odocoileus virginianus) fawns. Using GPS collars with short location-attempt intervals on 5 wolves and 5 deer during summers 2002-2004 in northeastern Minnesota, USA, demonstrated how this approach could provide new insights into wolf hunting behavior of fawns. For example, a wolf traveled ???1.5-3.0 km and spent 20-22 hours in the immediate vicinity of known fawn kill sites and ???0.7 km and 8.3 hours at scavenging sites. Wolf travel paths indicated that wolves intentionally traveled into deer summer ranges, traveled ???0.7-4.2 km in such ranges, and spent <1-22 hours per visit. Each pair of 3 GPS-collared wolf pack members were located together for ???6% of potential locations. From GPS collar data, we estimated that each deer summer range in a pack territory containing 5 wolves ???1 year old and hunting individually would be visited by a wolf on average every 3-5 days. This approach holds great potential for investigating summer hunting behavior of wolves in areas where direct observation is impractical or impossible.

  4. Gravity field error analysis - Applications of Global Positioning System receivers and gradiometers on low orbiting platforms

    NASA Technical Reports Server (NTRS)

    Schrama, Ernst J. O.

    1991-01-01

    The concept of a Global Positioning System (GPS) receiver as a tracking facility and a gradiometer as a separate instrument on a low-orbiting platform offers a unique tool to map the earth's gravitational field with unprecedented accuracies. The former technique allows determination of the spacecraft's ephemeris at any epoch to within 3-10 cm, the latter permits the measurement of the tensor of second order derivatives of the gravity field to within 0.01 to 0.0001 Eotvos units depending on the type of gradiometer. First, a variety of error sources in gradiometry where emphasis is placed on the rotational problem pursuing as well a static as a dynamic approach is described. Next, an analytical technique is described and applied for an error analysis of gravity field parameters from gradiometer and GPS observation types. Results are discussed for various configurations proposed on Topex/Poseidon, Gravity Probe-B, and Aristoteles, indicating that GPS only solutions may be computed up to degree and order 35, 55, and 85, respectively, whereas a combined GPS/gradiometer experiment on Aristoteles may result in an acceptable solution up to degree and order 240.

  5. Gravity field error analysis - Applications of Global Positioning System receivers and gradiometers on low orbiting platforms

    NASA Astrophysics Data System (ADS)

    Schrama, Ernst J. O.

    1991-11-01

    The concept of a Global Positioning System (GPS) receiver as a tracking facility and a gradiometer as a separate instrument on a low-orbiting platform offers a unique tool to map the earth's gravitational field with unprecedented accuracies. The former technique allows determination of the spacecraft's ephemeris at any epoch to within 3-10 cm, the latter permits the measurement of the tensor of second order derivatives of the gravity field to within 0.01 to 0.0001 Eotvos units depending on the type of gradiometer. First, a variety of error sources in gradiometry where emphasis is placed on the rotational problem pursuing as well a static as a dynamic approach is described. Next, an analytical technique is described and applied for an error analysis of gravity field parameters from gradiometer and GPS observation types. Results are discussed for various configurations proposed on Topex/Poseidon, Gravity Probe-B, and Aristoteles, indicating that GPS only solutions may be computed up to degree and order 35, 55, and 85, respectively, whereas a combined GPS/gradiometer experiment on Aristoteles may result in an acceptable solution up to degree and order 240.

  6. Maintenance of Time and Frequency in the DSN Using the Global Positioning System

    NASA Technical Reports Server (NTRS)

    Clements, P. A.; Kirk, A.; Borutzki, S. E.

    1985-01-01

    The Deep Space Network must maintain time and frequency within specified limits in order to accurately track the spacecraft engaged in deep space exploration. The DSN has three tracking complexes, located approximately equidistantly around the Earth. Various methods are used to coordinate the clocks among the three complexes. These methods include Loran-C, TV Line 10, very long baseline interferometry (VLBI), and the Global Positioning System (GPS). The GPS is becoming increasingly important because of the accuracy, precision, and rapid availability of the data; GPS receivers have been installed at each of the DSN complexes and are used to obtain daily time offsets between the master clock at each site and UTC(USNO/NBS). Calculations are made to obtain frequency offsets and Allan variances. These data are analyzed and used to monitor the performance of the hydrogen masers that provide the reference frequencies for the DSN frequency and timing system (DFT). A brief history of the GPS timing receivers in the DSN, a description of the data and information flow, data on the performance of the DSN master clocks and GPS measurement system, and a description of hydrogen maser frequency steering using these data are presented.

  7. High accuracy integrated global positioning system/inertial navigation system LDRD: Final report

    SciTech Connect

    Owen, T.E.; Meindl, M.A.; Fellerhoff, J.R.

    1997-03-01

    This report contains the results of a Sandia National Laboratories Directed Research and Development (LDRD) program to investigate the integration of Global Positioning System (GPS) and inertial navigation system (INS) technologies toward the goal of optimizing the navigational accuracy of the combined GPSANS system. The approach undertaken is to integrate the data from an INS, which has long term drifts, but excellent short term accuracy, with GPS carrier phase signal information, which is accurate to the sub-centimeter level, but requires continuous tracking of the GPS signals. The goal is to maintain a sub-meter accurate navigation solution while the vehicle is in motion by using the GPS measurements to estimate the INS navigation errors and then using the refined INS data to aid the GPS carrier phase cycle slip detection and correction and bridge dropouts in the GPS data. The work was expanded to look at GPS-based attitude determination, using multiple GPS receivers and antennas on a single platform, as a possible navigation aid. Efforts included not only the development of data processing algorithms and software, but also the collection and analysis of GPS and INS flight data aboard a Twin Otter aircraft. Finally, the application of improved navigation system accuracy to synthetic aperture radar (SAR) target location is examined.

  8. A Novel Sensor for Attitude Determination Using Global Positioning System Signals

    NASA Technical Reports Server (NTRS)

    Crassidis, John L.; Quinn, David A.; Markley, F. Landis; McCullough, Jon D.

    1998-01-01

    An entirely new sensor approach for attitude determination using Global Positioning System (GPS) signals is developed. The concept involves the use of multiple GPS antenna elements arrayed on a single sensor head to provide maximum GPS space vehicle availability. A number of sensor element configurations are discussed. In addition to the navigation function, the array is used to find which GPS space vehicles are within the field-of-view of each antenna element. Attitude determination is performed by considering the sightline vectors of the found GPS space vehicles together with the fixed boresight vectors of the individual antenna elements. This approach has clear advantages over the standard differential carrier-phase approach. First, errors induced by multipath effects can be significantly reduced or eliminated altogether. Also, integer ambiguity resolution is not required, nor do line biases need to be determined through costly and cumbersome self-surveys. Furthermore, the new sensor does not require individual antennas to be physically separated to form interferometric baselines to determine attitude. Finally, development potential of the new sensor is limited only by antenna and receiver technology development unlike the physical limitations of the current interferometric attitude determination scheme. Simulation results indicate that accuracies of about 1 degree (3 omega) are possible.

  9. Flight Test Results from Real-Time Relative Global Positioning System Flight Experiment on STS-69

    NASA Technical Reports Server (NTRS)

    Park, Young W.; Brazzel, Jack P., Jr.; Carpenter, J. Russell; Hinkel, Heather D.; Newman, James H.

    1996-01-01

    A real-time global positioning system (GPS) Kalman filter has been developed to support automated rendezvous with the International Space Station (ISS). The filter is integrated with existing Shuttle rendezvous software running on a 486 laptop computer under Windows. In this work, we present real-time and postflight results achieved with the filter on STS-69. The experiment used GPS data from an Osborne/Jet propulsion Laboratory TurboRouge receiver carried on the Wake Shield Facility (WSF) free flyer and a Rockwell Collins 3M receiver carried on the Orbiter. Real time filter results, processed onboard the Shuttle and replayed in near-time on the ground, are based on single vehicle mode operation and on 5 to 20 minute snapshots of telemetry provided by WSF for dual-vehicle mode operation. The Orbiter and WSF state vectors calculated using our filter compare favorably with precise reference orbits determined by the University of Texas Center for Space Research. The lessons learned from this experiment will be used in conjunction with future experiments to mitigate the technology risk posed by automated rendezvous and docking to the ISS.

  10. One century of tectonic deformation along the Sumatran fault from triangulation and Global Positioning System surveys

    NASA Astrophysics Data System (ADS)

    Prawirodirdjo, L.; Bock, Y.; Genrich, J. F.; Puntodewo, S. S. O.; Rais, J.; Subarya, C.; Sutisna, S.

    2000-12-01

    An analysis combining historical triangulation and recent Global Positioning System (GPS) survey measurements in west and north Sumatra, Indonesia, reveals a detailed slip history along the central part of the Sumatran fault. The arc-parallel components of the combined velocity field are consistent with slip rates inferred from GPS data, ranging from 23 to 24 mm/yr. Between 1.0°S and 1.3°N the Sumatran fault appears to be characterized by deep locking depths, of the order of 20 km, and the occurrence of large (Mw ≈ 7) earthquakes. The long-term (1883-1993) strains show simple right-lateral shear, with rates similar to GPS-measured, 1989-1993 strain rates. Coseismic deformation due to the 1892 Tapanuli and 1926 Padang Panjang earthquakes, estimated from triangulation measurements taken before and after the events, indicates that the main shocks were significantly larger than previously reported. The 1892 earthquake had a likely magnitude of Mw ≈ 7.6, while the 1926 events appear to be comparable in size to the subsequent (M ˜ 7) 1943 events and an order of magnitude higher than previously reported.

  11. Detection of traveling ionospheric disturbances induced by atmospheric gravity waves using the global positioning system

    NASA Technical Reports Server (NTRS)

    Bassiri, Sassan; Hajj, George A.

    1993-01-01

    Natural and man-made events like earthquakes and nuclear explosions launch atmospheric gravity waves (AGW) into the atmosphere. Since the particle density decreases exponentially with height, the gravity waves increase exponentially in amplitude as they propagate toward the upper atmosphere and ionosphere. As atmospheric gravity waves approach the ionospheric heights, the neutral particles carried by gravity waves collide with electrons and ions, setting these particles in motion. This motion of charged particles manifests itself by wave-like fluctuations and disturbances that are known as traveling ionospheric disturbances (TID). The perturbation in the total electron content due to TID's is derived analytically from first principles. Using the tilted dipole magnetic field approximation and a Chapman layer distribution for the electron density, the variations of the total electron content versus the line-of-sight direction are numerically analyzed. The temporal variation associated with the total electron content measurements due to AGW's can be used as a means of detecting characteristics of the gravity waves. As an example, detection of tsunami generated earthquakes from their associated atmospheric gravity waves using the Global Positioning System is simulated.

  12. Global Positioning System Navigation Above 76,000 km for NASA's Magnetospheric Multiscale Mission

    NASA Technical Reports Server (NTRS)

    Winternitz, Luke B.; Bamford, William A.; Price, Samuel R.; Carpenter, J. Russell; Long, Anne C.; Farahmand, Mitra

    2016-01-01

    NASA's Magnetospheric Multiscale (MMS) mission, launched in March of 2015, consists of a controlled formation of four spin-stabilized spacecraft in similar highly elliptic orbits reaching apogee at radial distances of 12 and 25 Earth radii (RE) in the first and second phases of the mission. Navigation for MMS is achieved independently on-board each spacecraft by processing Global Positioning System (GPS) observables using NASA Goddard Space Flight Center (GSFC)'s Navigator GPS receiver and the Goddard Enhanced Onboard Navigation System (GEONS) extended Kalman filter software. To our knowledge, MMS constitutes, by far, the highest-altitude operational use of GPS to date and represents a high point of over a decade of high-altitude GPS navigation research and development at GSFC. In this paper we will briefly describe past and ongoing high-altitude GPS research efforts at NASA GSFC and elsewhere, provide details on the design of the MMS GPS navigation system, and present on-orbit performance data from the first phase. We extrapolate these results to predict performance in the second phase orbit, and conclude with a discussion of the implications of the MMS results for future high-altitude GPS navigation, which we believe to be broad and far-reaching.

  13. A turn-key Concept for active cancellation of Global Positioning System L3 Signal

    NASA Astrophysics Data System (ADS)

    Nigra, Lou; Lewis, B. M.; Edgar, C. E.; Perillat, P.; Quintero, L.; Stanimirovic, S.; Gallagher, J. S., III

    2011-01-01

    We present a concept, developed at the National Astronomy and Ionosphere Center (NAIC) at Arecibo, Puerto Rico, for suppression of Global Positioning System (GPS) signals in the 305 m dish radio receiver path prior to backend processing. The subsystem does not require an auxiliary antenna and is intended for easy integration with radio telescope systems with a goal of being a turnkey addition to virtually any facility. We have focused on detection and cancellation of the GPS L3 signal at 1381.05 MHz which, during periodic test modes and particularly during system-wide tests, interfere with observations of objects in a range of redshifts that includes the Coma supercluster, for example. The signal can dynamically change modulation modes and our scheme has demonstrated, through simulations using actual sampled telescope data, the ability to acquire and track these signals as well as detect the mode changes in order to apply cancellation or blanking, as appropriate. The subsystem can also be adapted to GPS L1 (1575.42 MHz), L2C (1227.6 MHz), and others. A follow-up is underway to develop a prototype to deploy and evaluate at NAIC.

  14. Error Analysis System for Spacecraft Navigation Using the Global Positioning System (GPS)

    NASA Technical Reports Server (NTRS)

    Truong, S. H.; Hart, R. C.; Hartman, K. R.; Tomcsik, T. L.; Searl, J. E.; Bernstein, A.

    1997-01-01

    The Flight Dynamics Division (FDD) at the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) is currently developing improved space-navigation filtering algorithms to use the Global Positioning System (GPS) for autonomous real-time onboard orbit determination. In connection with a GPS technology demonstration on the Small Satellite Technology Initiative (SSTI)/Lewis spacecraft, FDD analysts and programmers have teamed with the GSFC Guidance, Navigation, and Control Branch to develop the GPS Enhanced Orbit Determination Experiment (GEODE) system. The GEODE system consists of a Kalman filter operating as a navigation tool for estimating the position, velocity, and additional states required to accurately navigate the orbiting Lewis spacecraft by using astrodynamic modeling and GPS measurements from the receiver. A parallel effort at the FDD is the development of a GPS Error Analysis System (GEAS) that will be used to analyze and improve navigation filtering algorithms during development phases and during in-flight calibration. For GEAS, the Kalman filter theory is extended to estimate the errors in position, velocity, and other error states of interest. The estimation of errors in physical variables at regular intervals will allow the time, cause, and effect of navigation system weaknesses to be identified. In addition, by modeling a sufficient set of navigation system errors, a system failure that causes an observed error anomaly can be traced and accounted for. The GEAS software is formulated using Object Oriented Design (OOD) techniques implemented in the C++ programming language on a Sun SPARC workstation. The Phase 1 of this effort is the development of a basic system to be used to evaluate navigation algorithms implemented in the GEODE system. This paper presents the GEAS mathematical methodology, systems and operations concepts, and software design and implementation. Results from the use of the basic system to evaluate

  15. High-frequency variations in Earth rotation from Global Positioning System data

    NASA Astrophysics Data System (ADS)

    Rothacher, M.; Beutler, G.; Weber, R.; Hefty, J.

    2001-01-01

    Using the data of the global, dense Global Positioning System (GPS) network established by the International GPS Service a continuous, uninterrupted series of subdaily Earth rotation parameters (ERPs) with a time resolution of 2 hours has been generated at the Center for Orbit Determination in Europe. The series starts in January 1995 and has a length of more than 3 years. Starting from the 2-hour ERP values of this, to our knowledge, unique time series, the high-frequency variations in Universal Time (UT1) and polar motion (PM) due to ocean tides are studied and a set of sine and cosine coefficients is estimated for all the major tidal terms at nearly diurnal and semidiurnal frequencies. The GPS series is not very homogeneous (various processing changes during the 3 years) and still short compared to the length of very long baseline interferometry (VLBI) and satellite laser ranging (SLR) data sets. However, the results derived from this series are already of the same quality as the results from VLBI and SLR. A comparison of the tidal coefficients stemming from all three space-geodetic techniques shows an agreement on the 1 μs level for UT1 and 10 microarc seconds (μas) for PM, respectively. The RMS difference between the ocean tide amplitudes estimated from GPS data and from TOPEX/Poseidon altimeter data amounts to 0.7-0.9 μs in UT1 and 9-13 μas in PM. The residual spectrum that remains after the removal of all tidal terms has a noise level of ˜5-10 μas in PM and 0.5-1 μs in UT1 and contains nontidal signals (up to 55 μas in PM and 3 μs in UT1) that might be due to the impact of the satellite orbit modeling (12-hour revolution period of the satellites) or, alternatively, due to atmospheric or oceanic normal modes.

  16. Rift-transform kinetics in south Ireland: Deformation from Global Positioning System measurements, 1986 to 1992

    NASA Astrophysics Data System (ADS)

    Sigmundsson, Freysteinn; Einarsson, Pall; Bilham, Roger; Sturkell, Erik

    1995-04-01

    Crustal deformation in the plate boundary regions in south Iceland is estimated from repeated Global Positioning System (GPS) geodetic measurements in the period 1986-1992. We compare coordinate solutions for the 1986 and 1989 surveys with the results from the most recent survey in 1992. Horizontal position uncertainty is about 2 cm for the 1986 and 1989 coordinates are about 4 mm for the 1992 coordinates. Little internal deformation is observed in the area west of the western volcanic zone (within the North American Plate) and at the southern tip of the eastern volcanic zone (within the Eurasian plate). The observed relative velocity of these two areas is 2.1 +/- 0.4 cm/yr in direction N117 +/- 11 deg E (1 sigma uncertainties), compatible with the 1.94 cm/yr widening in direction N104 deg E across south Iceland predicted from the NUVEL-1 global plate motion model. Left-lateral shear strain is developing across the intervening transform zone, the E-W trending south Iceland seismic zone (SISZ). Strain is concentrated within a 20- to 30-km-wide zone that correlates with seismic activity in the SISZ. About 85 +/- 15% of the relative plate motion is accommodated by this zone in such a way that the area south of the SISZ is moving toward the east with the Eurasian plate and the area north of the SISZ is moving toward the west with the North American plate. Accordingly, north of the SISZ the western rift zone can accommodate a maximum of 15 +/- 15% of the relative plate motion. Within thw SISZ the shear strain results in an anticlockwise rotation of lineaments oriented north-south, at a rate of 0.5-1 micro-rad/yr. The shear strain accumulation can be accommodated by 'bookshelf faulting' on mapped recent north-south faults in the SISZ. If the deformation is accommodated by an array of N-S faults spaced 1-5 km apart, an average slip rate of about 0.5-5 mm/yr is required on each fault. The rate of geometric moment release due to earthquakes averaged over centuries, m(sub o

  17. Movement analysis of Australian national league soccer players using global positioning system technology.

    PubMed

    Wehbe, George M; Hartwig, Timothy B; Duncan, Craig S

    2014-03-01

    Player activity profiles of match play provide valuable information for optimal athlete training prescriptions, competition strategies, and managing load and recovery and are currently lacking in elite Australian-league (A-League) soccer. The aims of the study were, therefore, to (a) determine match activity profiles for elite A-League soccer players and make match-half and positional comparisons and (b) examine the effect of situational factors including evolving match status (drawing, winning, or losing) and goals being scored and conceded on selected match activity profile variables. Global positioning system tracking devices were used to determine activity profiles of 19 elite male adult soccer players during 8 preseason matches (n = 95 files). Total distance, average speed, high-intensity running (HIR) distance, and very high-intensity running distance decreased from the first to the second half by 7.92, 9.47, 10.10, and 10.99%, respectively. Midfielders covered 11.69% more total distance, 28.08% more HIR distance, and had a 10.93% higher average speed than defenders (p ≤ 0.05; d = 1.90, 1.03, and 1.83, respectively). Attackers performed 27.50 and 30.24% less medium accelerations than defenders and midfielders, respectively (p < 0.01; d = 1.54, and 1.73). When the team was winning, average speed was 4.17% lower than when the team was drawing (p ≤ 0.05, d = 0.32). Scoring or conceding goals did not appear to affect HIR. This study adds to limited knowledge of match demands in elite A-League soccer. The match activity profiles provide descriptive benchmarks that could be used to make comparisons with other elite level soccer populations while also providing a framework for game-specific training prescription, competition strategy, and load management. The generalization that defenders experience a relatively lower match load may be questionable given their relatively high acceleration and deceleration demands.

  18. Defining space use and movements of Canada lynx with global positioning system telemetry

    USGS Publications Warehouse

    Burdett, C.L.; Moen, R.A.; Niemi, G.J.; Mech, L.D.

    2007-01-01

    Space use and movements of Canada lynx (Lynx canadensis) are difficult to study with very-high-frequency radiocollars. We deployed global positioning system (GPS) collars on 11 lynx in Minnesota to study their seasonal space-use patterns. We estimated home ranges with minimum-convex-polygon and fixed-kernel methods and estimated core areas with area/probability curves. Fixed-kernel home ranges of males (range = 29-522 km2) were significantly larger than those of females (range = 5-95 km2) annually and during the denning season. Some male lynx increased movements during March, the month most influenced by breeding activity. Lynx core areas were predicted by the 60% fixed-kernel isopleth in most seasons. The mean core-area size of males (range = 6-190 km2) was significantly larger than that of females (range = 1-19 km2) annually and during denning. Most female lynx were reproductive animals with reduced movements, whereas males often ranged widely between Minnesota and Ontario. Sensitivity analyses examining the effect of location frequency on home-range size suggest that the home-range sizes of breeding females are less sensitive to sample size than those of males. Longer periods between locations decreased home-range and core-area overlap relative to the home range estimated from daily locations. GPS collars improve our understanding of space use and movements by lynx by increasing the spatial extent and temporal frequency of monitoring and allowing home ranges to be estimated over short periods that are relevant to life-history characteristics. ?? 2007 American Society of Mammalogists.

  19. Evaluating home range techniques: use of Global Positioning System (GPS) collar data from chacma baboons.

    PubMed

    Pebsworth, Paula A; Morgan, Hanna R; Huffman, Michael A

    2012-10-01

    Global Positioning System (GPS) collars have revolutionized the field of spatial ecology, but to date, few primate studies have used them. We fitted a free-ranging, semi-habituated, juvenile male chacma baboon (Papio hamadryas ursinus) with an automatic self-releasing GPS collar and tracked his movements for 359 days. The collar captured 4254 fixes out of 5719 programmed opportunities, a 74.4 % acquisition rate, suggesting that the collar effectively tracked this baboon in a variety of habitat types. Of the data points captured, 73.7 % were three-dimensional fixes, and of these fixes, 66.9 % were highly accurate, having a dilution of precision of less than four. We calculated home range using three protocols with three estimation methods: minimum convex polygon, fixed kernel-density estimation (KDE), and fixed r local convex hull. Using all data points and the 95 % contour, these methods created home range estimations ranging from 10.8 to 23.1 km(2) for this baboon troop. Our results indicate that the KDE output using all data locations most accurately represented our data set, as it created a continuous home range boundary that excluded unused areas and outlying, potentially exploratory data points while including all seven sleeping sites and a movement corridor. However, home range estimations generated from KDE varied from 15.4 to 18.8 km(2) depending on the smoothing parameter used. Our results demonstrated that the ad hoc smoothing parameter selection technique was a better method for our data set than either the least squares cross-validation or biased cross-validation techniques. Our results demonstrate the need for primatologists to develop a standardized reporting method which documents the tool, screening protocol, and smoothing parameter used in the creation of home range estimations in order to make comparisons that are meaningful.

  20. Combining global positioning system and accelerometer data to determine the locations of physical activity in children.

    PubMed

    Oreskovic, Nicolas M; Blossom, Jeff; Field, Alison E; Chiang, Sylvia R; Winickoff, Jonathan P; Kleinman, Ronald E

    2012-05-01

    National trends indicate that children and adolescents are not achieving sufficient levels of physical activity. Combining global positioning system (GPS) technology with accelerometers has the potential to provide an objective determination in locations where youth engage in physical activity. The aim of this study was to identify the optimal methods for collecting combined accelerometer and GPS data in youth, to best locate where children spend time and are physically active. A convenience sample of 24 mid-school children in Massachusetts was included. Accelerometers and GPS units were used to quantify and locate childhood physical activity over 5 weekdays and 2 weekend days. Accelerometer and GPS data were joined by time and mapped with a geographical information system (GIS) using ArcGIS software. Data were collected in winter, spring, summer in 2009-2010, collecting a total of 26,406 matched datapoints overall. Matched data yield was low (19.1% total), regardless of season (winter, 12.8%; spring, 30.1%; summer, 14.3%). Teacher-provided, pre-charged equipment yielded the most matched (30.1%; range: 10.1-52.3%) and greatest average days (6.1 days) of data. Across all seasons, children spent most of their time at home. Outdoor use patterns appeared to vary by season, with street use increasing in spring, and park and playground use increasing in summer. Children spent equal amounts of physical activity time at home and walking in the streets. Overall, the various methods for combining GPS and accelerometer data provided similarly low amounts of combined data. No combined GPS and accelerometer data collection method proved superior in every data return category, but use of GIS to map joined accelerometer and GPS data can demarcate childhood physical activity locations.

  1. A GIS Method of Calculating Snow Depth Using IFSAR Data and Differential Global Position System

    NASA Astrophysics Data System (ADS)

    Hinkel, K. M.; Hurd, J. K.

    2005-12-01

    Recent advances in remote sensing platforms, Differential Global Positioning Systems (DGPS) technology, and Geographic Information Systems (GIS) capabilities has led to multiple ways of creating high resolution Digital Elevation Models (DEM). In April 2005 near Barrow, Alaska, a DGPS survey was conducted along a snowdrift formed by a 2.2 km long snow fence. A snow machine was used to pull a sledge equipped with the DGPS, recording geographic location and elevation every 5 seconds. Surveys were conducted along five transects parallel to the snow fence; two along the upwind (eastern) side of the fence and three along the deeper downwind (western) drift. The path of the snow machine was along the drift crest, slope and edge. In addition to the DGPS survey of the snowdrift, Interferometric Synthetic Aperture Radar (IFSAR) data collected in July 2002 by InterMapr was used as a DEM of the ground surface. Within the GIS software package, the DGPS survey points were interpolated using a triangulated irregular network. This surface was rasterized to 5 m2 cells to match the IFSAR DEM. Using a raster calculator, the ground surface DEM was subtracted from the snowdrift DEM to yield a DEM of snow depth. Integrated over the length and width of the affected area, the drift covers an area of 186,900 m2 and contains a volume of 415,858 m3. The mean snow depth is 2.23 m as compared to 0.4 m at a control site located in a nearby region of the tundra unaffected by the snow fence. Empirical measurements were collected with a calibrated metal snow depth probe along transects perpendicular to the snow fence, and were used for an accuracy assessment. The results show agreement to about +/-20 cm. Some Arctic villages rely on snowdrifts as a source of drinking water. Using these techniques, the snow water equivalent can be calculated given a know snow density to estimate fresh water availability.

  2. On Use of Global Positioning Technology for Solution of Wake Vortex Problem

    NASA Technical Reports Server (NTRS)

    Rossow, Vernon J.; Olson, Lawerence E. (Technical Monitor)

    1997-01-01

    Improved precision of the flight paths used by aircraft to approach and depart airports is becoming available when the Global Positioning System (GPS) is implemented at airports. An overview will be given of published information on how GPS precision guidance at airports can be used to avoid encounters with the lift-generated vortices shed by preceding aircraft during landing. It is pointed out that GPS provides two needed services to bring about improved avoidance capability. Firstly, GPS pseudolites are being built and installed at airports so that, when coupled with autopilot systems currently available on subsonic transport aircraft, the aircraft can make precision approaches for zero visibility landings. The same equipment can also be used for precision approaches for wake-vortex avoidance. Secondly, regular monitoring of atmospheric motions along the approach corridor can be obtained by use of GPS equipment on board aircraft that are in the flight corridors. That is, wind velocity is determined by use of GPS equipment to measure the ground speed of the aircraft and then combined with onboard instrumentation to measure the airspeed of the aircraft. The difference between the two measurements yields the wind velocity. When the measured wind velocities are transmitted to an airport ground station they are used to monitor whether air motions adverse for safety in the flight corridor are present. If any parts of the corridor are unsafe, the spacing of the aircraft, or the location of the flight corridor being used, is modified. It is estimated that the spacings between any combination of aircraft can then be safely reduced to a uniform 3 n. mi. Information to be presented is contained in an article published in the AIAA Journal of Aircraft, May-June 1996.

  3. Evaluation of Two Computational Techniques of Calculating Multipath Using Global Positioning System Carrier Phase Measurements

    NASA Technical Reports Server (NTRS)

    Gomez, Susan F.; Hood, Laura; Panneton, Robert J.; Saunders, Penny E.; Adkins, Antha; Hwu, Shian U.; Lu, Ba P.

    1996-01-01

    Two computational techniques are used to calculate differential phase errors on Global Positioning System (GPS) carrier war phase measurements due to certain multipath-producing objects. The two computational techniques are a rigorous computati electromagnetics technique called Geometric Theory of Diffraction (GTD) and the other is a simple ray tracing method. The GTD technique has been used successfully to predict microwave propagation characteristics by taking into account the dominant multipath components due to reflections and diffractions from scattering structures. The ray tracing technique only solves for reflected signals. The results from the two techniques are compared to GPS differential carrier phase ns taken on the ground using a GPS receiver in the presence of typical International Space Station (ISS) interference structures. The calculations produced using the GTD code compared to the measured results better than the ray tracing technique. The agreement was good, demonstrating that the phase errors due to multipath can be modeled and characterized using the GTD technique and characterized to a lesser fidelity using the DECAT technique. However, some discrepancies were observed. Most of the discrepancies occurred at lower devations and were either due to phase center deviations of the antenna, the background multipath environment, or the receiver itself. Selected measured and predicted differential carrier phase error results are presented and compared. Results indicate that reflections and diffractions caused by the multipath producers, located near the GPS antennas, can produce phase shifts of greater than 10 mm, and as high as 95 mm. It should be noted tl the field test configuration was meant to simulate typical ISS structures, but the two environments are not identical. The GZ and DECAT techniques have been used to calculate phase errors due to multipath o the ISS configuration to quantify the expected attitude determination errors.

  4. Evaluation of movement and physiological demands of rugby league referees using global positioning systems tracking.

    PubMed

    O'Hara, J P; Brightmore, A; Till, K; Mitchell, I; Cummings, S; Cooke, C B

    2013-09-01

    The use of global positioning systems (GPS) technology within referees of any sport is limited. Therefore, the purpose of the current study was to evaluate the movement and physiological demands of professional rugby league referees using GPS tracking analysis. Time-motion analysis was undertaken on 8 referees using 5-Hz GPS devices and heart rate monitors throughout a series of Super League matches. 44 data sets were obtained with results identifying similar total distance covered between first and second half periods with a significant (P=0.004) reduction in the number of high velocity efforts performed between 5.51-7.0 m.s-1 (1st=21±8, 2nd=18±8). Mean distance covered from greatest to least distance, was 3 717±432 m, 3 009±402 m, 1 411±231 m, 395±133 m and 120±97 m for the following 5 absolute velocity classifications, respectively; 0.51-2.0 m.s-1; 2.1-4.0 m.s-1: 4.01-5.5 m.s-1; 5.51-7.0 m.s-1; <7.01 m.s-1. Heart rate was significantly (P<0.001) greater in the first (85.5±3.4% maxHR) compared to the second (82.9±3.8% maxHR) half. This highlights the intermittent nature of rugby league refereeing, consisting of low velocity activity interspersed with high velocity efforts and frequent changes of velocity. Training should incorporate interval training interspersing high velocity efforts of varying distances with low velocity activity while trying to achieve average heart rates of ~ 84% maxHR to replicate the physiological demands.

  5. Localization of Physical Activity in Primary School Children Using Accelerometry and Global Positioning System

    PubMed Central

    Bürgi, Rahel; Tomatis, Laura; Murer, Kurt; de Bruin, Eling D.

    2015-01-01

    Background Ecological approaches have highlighted the importance of the built environment as a factor affecting physical activity. However, knowledge on children’s activity patterns is still incomplete. Particularly, data on the spatial context of physical activity is limited, which limits the potential to design location-based interventions effectively. Using global positioning system (GPS) and accelerometry, this study aimed to identify locations where children engage in moderate-vigorous physical activity (MVPA). Methods Participants included 119 children (11–14 years, 57% girls) from public schools in Winterthur, Switzerland. During a regular school week between February and April 2013, children wore an accelerometer and GPS sensor for seven consecutive days. Time-matched accelerometer and GPS data was mapped with a geographic information system and each data point was assigned to one of seven defined activity settings. Both the absolute amount of MVPA and proportion of time in MVPA were calculated for every setting. Multilevel analyses accounting for the hierarchical structure of the data were conducted to investigate any gender differences. Results Children achieved most MVPA on streets (34.5%) and on school grounds (33.4%). The proportion children spent in MVPA was highest in recreational facilities (19.4%), at other schools (19.2%) and on streets (18.6%). Boys accumulated significantly more MVPA overall and on other school grounds (p < 0.05) and showed a significantly higher proportion of time in MVPA at own school and outside of Winterthur (p < 0.05). Conclusions The results indicate the importance of streets and school grounds as activity-promoting environments. The high use of streets may be an indicator for active transportation, which appears to contribute to an active lifestyle in both genders. In contrast, the school setting is more likely to encourage physical activity in boys. Recreational facilities seem to be conducive for MVPA among both

  6. Northwest Basin and Range tectonic deformation observed with the Global Positioning System, 1999-2003

    USGS Publications Warehouse

    Hammond, W.C.; Thatcher, W.

    2005-01-01

    We use geodetic velocities obtained with the Global Positioning System (GPS) to quantify tectonic deformation of the northwest Basin and Range province of the western United States. The results are based on GPS data collected in 1999 and 2003 across five new quasi-linear networks in northern Nevada, northeast California, and southeast Oregon. The velocities show ???3 mm/yr westward movement of northern Nevada with respect to stable North America. West of longitude 119??W the velocities increase and turn northwest, parallel to Sierra Nevada/Great Valley microplate motion, and similar to velocities previously obtained to the south. The observations are explained by a kinematic model with three domains that rotate around Euler poles in eastern Oregon and western Idaho. Northeast California experiences internal dextral shear deformation (11.2 ?? 3.6 nstrain/yr) subparallel to Pacific/North America motion. Relative motions of the domains imply 2-5 mm/yr approximately east-west extension in northwest Nevada and 1-4 mm/yr approximately north-south contraction near the California/Oregon border. The northward decreasing approximately east-west extension in northwest Nevada is consistent with the northern termination of Basin and Range deformation, faulting and characteristic topography. No significant extension is detected in the Oregon Basin and Range. The Oregon Cascade arc moves north at ???3.5 mm/yr and is possibly influenced by the approximately eastward motion of the Juan de Fuca plate. These results disagree with secular northwest trenchward motion of the Oregon forearc inferred from paleomagnetic rotations. South of latitude 43??, however, trenchward motion exists and is consistent with block rotations, approximately east-west Basin and Range extension, and northwest Sierra Nevada translation. Copyright 2005 by the American Geophysical Union.

  7. Identification of underground mine workings with the use of global positioning system technology

    SciTech Connect

    Canty, G.A.; Everett, J.W.; Sharp, M.

    1998-12-31

    Identification of underground mine workings for well drilling is a difficult task given the limited resources available and lack of reliable information. Relic mine maps of questionable accuracy and difficulty in correlating the subsurface to the surface, make the process of locating wells arduous. With the development of global positioning system (GPS), specific locations on the earth can be identified with the aid of satellites. This technology can be applied to mine workings identification given a few necessary, precursory details. For an abandoned mine treatment project conducted by the University of Oklahoma, in conjunction with the Oklahoma Conservation Commission, a Trimble ProXL 8 channel GPS receiver was employed to locate specific points on the surface with respect to a mine map. A 1925 mine map was digitized into AutoCAD version 13 software. Surface features identified on the map, such as mine adits, were located and marked in the field using the GPS receiver. These features were than imported into AutoCAD and referenced with the same points drawn on the map. A rubber sheeting program, Multric, was used to tweak the points so the map features correlated with the surface points. The correlation of these features allowed the map to be geo-referenced with the surface. Specific drilling points were located on the digitized map and assigned a latitude and longitude. The GPS receiver, using real time differential correction, was used to locate these points in the field. This method was assumed to be relatively accurate, to within 5 to 15 feet.

  8. Global Positioning System: a new tool for measurement of animal bites in a rural area near Bangalore, South India.

    PubMed

    Masthi, N R Ramesh; Undi, Malatesh

    2014-10-01

    This exploratory study was conducted in villages near Bangalore, South India with the primary objective of spatial mapping animal bite cases using Global Positioning System (GPS) technology. GPS technology was useful as a new tool in accurate measurement of animal bite cases.

  9. An Inquiry-Based Approach to Teaching the Spherical Earth Model to Preservice Teachers Using the Global Positioning System

    ERIC Educational Resources Information Center

    Song, Youngjin; Schwenz, Richard

    2013-01-01

    This article describes an inquiry-based lesson to deepen preservice teachers' understanding of the spherical Earth model using the Global Positioning System. The lesson was designed with four learning goals: (1) to increase preservice teachers' conceptual knowledge of the spherical Earth model; (2) to develop preservice teachers'…

  10. A Group-learning Approach to Academic and Transferable Skills through an Exercise in the Global Positioning System.

    ERIC Educational Resources Information Center

    Brown, Giles H.

    1999-01-01

    Describes a project based on the Global Positioning System (GPS) that offers students a chance to design and implement a mini-research program to prepare them for an undergraduate research project. Discusses the context of the GPS exercise, teaching and learning outcomes, and advantages and evaluation of the exercise. (CMK)

  11. Getting from Here to There and Knowing Where: Teaching Global Positioning Systems to Students with Visual Impairments

    ERIC Educational Resources Information Center

    Phillips, Craig L.

    2011-01-01

    Global Positioning Systems' (GPS) technology is available for individuals with visual impairments to use in wayfinding and address Lowenfeld's "three limitations of blindness." The considerations and methodologies for teaching GPS usage have developed over time as GPS information and devices have been integrated into orientation and mobility…

  12. Nonparametric Bayesian Filtering for Location Estimation, Position Tracking, and Global Localization of Mobile Terminals in Outdoor Wireless Environments

    NASA Astrophysics Data System (ADS)

    Khalaf-Allah, Mohamed

    2007-12-01

    The mobile terminal positioning problem is categorized into three different types according to the availability of (1) initial accurate location information and (2) motion measurement data. Location estimation refers to the mobile positioning problem when both the initial location and motion measurement data are not available. If both are available, the positioning problem is referred to as position tracking. When only motion measurements are available, the problem is known as global localization. These positioning problems were solved within the Bayesian filtering framework. Filter derivation and implementation algorithms are provided with emphasis on the mapping approach. The radio maps of the experimental area have been created by a 3D deterministic radio propagation tool with a grid resolution of 5 m. Real-world experimentation was conducted in a GSM network deployed in a semiurban environment in order to investigate the performance of the different positioning algorithms.

  13. Multi-antenna synchronized global navigation satellite system receiver and its advantages in high-precision positioning applications

    NASA Astrophysics Data System (ADS)

    Dong, Danan; Chen, Wen; Cai, Miaomiao; Zhou, Feng; Wang, Minghua; Yu, Chao; Zheng, Zhengqi; Wang, Yuanfei

    2016-02-01

    The multi-antenna synchronized global navigation satellite system receiver is a high precision, low cost, and widely used emerging receiver. Using this type of receiver, the satellite and receiver clock errors can be eliminated simultaneously by forming between antenna single-differences, which is equivalent to the conventional double-difference model. However, current multi-antenna synchronized global navigation satellite system receiver products have not fully realized their potential to achieve better accuracy, efficiency, and broader applications. This paper introduces the conceptual design and derivable products of multi-antenna synchronized global navigation satellite system receivers involving the aspects of attitude determination, multipath effect mitigation, phase center variation correction, and ground-based carrier phase windup calibration. Through case studies, the advantages of multi-antenna synchronized global navigation satellite system receivers in high-precision positioning applications are demonstrated.

  14. Ranging airport pseudolite for local area augmentation using the global positioning system

    NASA Astrophysics Data System (ADS)

    Bartone, Chris Gregory

    The Local Area Augmentation System (LAAS) is being developed to support precision approach and landing operations in and about the local area surrounding an airport. The LAAS Program is currently under development by the Federal Aviation Administration (FAA) with Minimum Aviation System Performance Standards for the LAAS being developed by RTCA, Incorporated. The LAAS uses differential Global Positioning System (DGPS) and includes one or more airport pseudolites (APL) to increase the availability for certain installations. This dissertation addresses the addition of a differentially corrected, ranging APL into a LAAS. Prior to this work, no ranging APL has been integrated into a prototype LAAS and demonstrated in a real-time flight environment showing that an increase in LAAS availability is feasible. The APL requirements resulted in a prototype APL transmitting and receiving subsystem with a coarse-acquisition (C/A) code format that could be operated at any frequency within the L1± 10.0 MHz band. To investigate the major APL error the developmental approach was performed in two phases. Phase I implemented an APL operating at a center frequency off-L1 and concentrated on multipath limiting. The Phase II on-L1 APL architecture implemented a unique pulsing, automatic gain control (AGC) and GPS Blanker technique in the common reception path to maximize APL signal tracking and minimize electromagnetic interference to DGPS. To minimize ground multipath for the APL geometry, which is more severe than for GPS, a multipath limiting antenna (MLA) was designed, fabricated, and tested within a 4-month period. The implementation of this MLA concept was a first for APL applications and also contributed to the successful multipath limiting of ground multipath at the DGPS LAAS Ground Station. This effort successfully demonstrated that ground multipath can be limited (with low variance and no long-term bias) for the APL geometry and that suitable precision approach performance

  15. Refining Time-Activity Classification of Human Subjects Using the Global Positioning System

    PubMed Central

    Hu, Maogui; Li, Wei; Li, Lianfa; Houston, Douglas; Wu, Jun

    2016-01-01

    Background Detailed spatial location information is important in accurately estimating personal exposure to air pollution. Global Position System (GPS) has been widely used in tracking personal paths and activities. Previous researchers have developed time-activity classification models based on GPS data, most of them were developed for specific regions. An adaptive model for time-location classification can be widely applied to air pollution studies that use GPS to track individual level time-activity patterns. Methods Time-activity data were collected for seven days using GPS loggers and accelerometers from thirteen adult participants from Southern California under free living conditions. We developed an automated model based on random forests to classify major time-activity patterns (i.e. indoor, outdoor-static, outdoor-walking, and in-vehicle travel). Sensitivity analysis was conducted to examine the contribution of the accelerometer data and the supplemental spatial data (i.e. roadway and tax parcel data) to the accuracy of time-activity classification. Our model was evaluated using both leave-one-fold-out and leave-one-subject-out methods. Results Maximum speeds in averaging time intervals of 7 and 5 minutes, and distance to primary highways with limited access were found to be the three most important variables in the classification model. Leave-one-fold-out cross-validation showed an overall accuracy of 99.71%. Sensitivities varied from 84.62% (outdoor walking) to 99.90% (indoor). Specificities varied from 96.33% (indoor) to 99.98% (outdoor static). The exclusion of accelerometer and ambient light sensor variables caused a slight loss in sensitivity for outdoor walking, but little loss in overall accuracy. However, leave-one-subject-out cross-validation showed considerable loss in sensitivity for outdoor static and outdoor walking conditions. Conclusions The random forests classification model can achieve high accuracy for the four major time

  16. Physical activity intensity can be accurately monitored by smartphone global positioning system 'app'.

    PubMed

    Gordon, Brett Ashley; Bruce, Lyndell; Benson, Amanda Clare

    2016-08-01

    Monitoring physical activity is important to better individualise health and fitness benefits. This study assessed the concurrent validity of a smartphone global positioning system (GPS) 'app' and a sport-specific GPS device with a similar sampling rate, to measure physical activity components of speed and distance, compared to a higher sampling sport-specific GPS device. Thirty-eight (21 female, 17 male) participants, mean age of 24.68, s = 6.46 years, completed two 2.400 km trials around an all-weather athletics track wearing GPSports Pro™ (PRO), GPSports WiSpi™ (WISPI) and an iPhone™ with a Motion X GPS™ 'app' (MOTIONX). Statistical agreement, assessed using t-tests and Bland-Altman plots, indicated an (mean; 95% LOA) underestimation of 2% for average speed (0.126 km·h(-1); -0.389 to 0.642; p < .001), 1.7% for maximal speed (0.442 km·h(-1); -2.676 to 3.561; p = .018) and 1.9% for distance (0.045 km; -0.140 to 0.232; p < .001) by MOTIONX compared to that measured by PRO. In contrast, compared to PRO, WISPI overestimated average speed (0.232 km·h(-1); -0.376 to 0.088; p < .001) and distance (0.083 km; -0.129 to -0.038; p < .001) by 3.5% whilst underestimating maximal speed by 2.5% (0.474 km·h(-1); -1.152 to 2.099; p < .001). Despite the statistically significant difference, the MOTIONX measures intensity of physical activity, with a similar error as WISPI, to an acceptable level for population-based monitoring in unimpeded open-air environments. This presents a low-cost, minimal burden opportunity to remotely monitor physical activity participation to improve the prescription of exercise as medicine.

  17. Predicting Ambulance Time of Arrival to the Emergency Department Using Global Positioning System and Google Maps

    PubMed Central

    Fleischman, Ross J.; Lundquist, Mark; Jui, Jonathan; Newgard, Craig D.; Warden, Craig

    2014-01-01

    arrival to the emergency department with good accuracy. This model could be linked to global positioning system data and an automated Google Maps web application to optimize emergency department resource use. Use of lights and sirens had a significant effect on transport times. PMID:23865736

  18. Physical activity intensity can be accurately monitored by smartphone global positioning system 'app'.

    PubMed

    Gordon, Brett Ashley; Bruce, Lyndell; Benson, Amanda Clare

    2016-08-01

    Monitoring physical activity is important to better individualise health and fitness benefits. This study assessed the concurrent validity of a smartphone global positioning system (GPS) 'app' and a sport-specific GPS device with a similar sampling rate, to measure physical activity components of speed and distance, compared to a higher sampling sport-specific GPS device. Thirty-eight (21 female, 17 male) participants, mean age of 24.68, s = 6.46 years, completed two 2.400 km trials around an all-weather athletics track wearing GPSports Pro™ (PRO), GPSports WiSpi™ (WISPI) and an iPhone™ with a Motion X GPS™ 'app' (MOTIONX). Statistical agreement, assessed using t-tests and Bland-Altman plots, indicated an (mean; 95% LOA) underestimation of 2% for average speed (0.126 km·h(-1); -0.389 to 0.642; p < .001), 1.7% for maximal speed (0.442 km·h(-1); -2.676 to 3.561; p = .018) and 1.9% for distance (0.045 km; -0.140 to 0.232; p < .001) by MOTIONX compared to that measured by PRO. In contrast, compared to PRO, WISPI overestimated average speed (0.232 km·h(-1); -0.376 to 0.088; p < .001) and distance (0.083 km; -0.129 to -0.038; p < .001) by 3.5% whilst underestimating maximal speed by 2.5% (0.474 km·h(-1); -1.152 to 2.099; p < .001). Despite the statistically significant difference, the MOTIONX measures intensity of physical activity, with a similar error as WISPI, to an acceptable level for population-based monitoring in unimpeded open-air environments. This presents a low-cost, minimal burden opportunity to remotely monitor physical activity participation to improve the prescription of exercise as medicine. PMID:26505223

  19. Global Positioning System (GPS) Precipitable Water in Forecasting Lightning at Spaceport Canaveral

    NASA Technical Reports Server (NTRS)

    Kehrer, Kristen C.; Graf, Brian; Roeder, William

    2006-01-01

    This paper evaluates the use of precipitable water (PW) from Global Positioning System (GPS) in lightning prediction. Additional independent verification of an earlier model is performed. This earlier model used binary logistic regression with the following four predictor variables optimally selected from a candidate list of 23 candidate predictors: the current precipitable water value for a given time of the day, the change in GPS-PW over the past 9 hours, the KIndex, and the electric field mill value. This earlier model was not optimized for any specific forecast interval, but showed promise for 6 hour and 1.5 hour forecasts. Two new models were developed and verified. These new models were optimized for two operationally significant forecast intervals. The first model was optimized for the 0.5 hour lightning advisories issued by the 45th Weather Squadron. An additional 1.5 hours was allowed for sensor dwell, communication, calculation, analysis, and advisory decision by the forecaster. Therefore the 0.5 hour advisory model became a 2 hour forecast model for lightning within the 45th Weather Squadron advisory areas. The second model was optimized for major ground processing operations supported by the 45th Weather Squadron, which can require lightning forecasts with a lead-time of up to 7.5 hours. Using the same 1.5 lag as in the other new model, this became a 9 hour forecast model for lightning within 37 km (20 NM)) of the 45th Weather Squadron advisory areas. The two new models were built using binary logistic regression from a list of 26 candidate predictor variables: the current GPS-PW value, the change of GPS-PW over 0.5 hour increments from 0.5 to 12 hours, and the K-index. The new 2 hour model found the following for predictors to be statistically significant, listed in decreasing order of contribution to the forecast: the 0.5 hour change in GPS-PW, the 7.5 hour change in GPS-PW, the current GPS-PW value, and the KIndex. The new 9 hour forecast model found

  20. Ionospheric Signature of Surface Mine Blasts from Global Positioning System Measurements

    NASA Technical Reports Server (NTRS)

    Calais, Eric; Minster, J. Bernard; Hofton, Michelle A.; Hedlin, Michael A. H.

    1998-01-01

    Sources such as atmospheric or buried explosions and shallow earthquakes are known to produce infrasonic pressure waves in the atmosphere. Because of the coupling between neutral particles and electrons at ionospheric altitudes, these acoustic and gravity waves induce variations of the ionospheric electron density. The Global Positioning System (GPS) provides a way of directly measuring the total electron content in the ionosphere and, therefore, of detecting such perturbations in the upper atmosphere. In July and August 1996, three large surface mine blasts (1.5 Kt each) were detonated at the Black Thunder coal mine in eastern Wyoming. As part of a seismic and acoustic monitoring- experiment, we deployed five dual-frequency GPS receivers at distances ranging from 50 to 200 km from the mine and were able to detect the ionospheric perturbation caused by the blasts. The perturbation starts 10 to 15 min after the blast, lasts for about 30 min, and propagates with an apparent horizontal velocity of 1200 meters per second. Its amplitude reaches 3 x 10 (exp 14) el per square meters in the 7-3 min period band, a value close to the ionospheric perturbation caused by the M = 6.7 Northridge earthquake. The small signal-to-noise ratio of the perturbation can be improved by slant-stacking the electron content time-series recorded by the different GPS receivers taking into account the horizontal propagation of the perturbation. The energy of the perturbation is concentrated in the 200 to 300 second period band, a result consistent with previous observations and numerical model predictions. The 300 second band probably corresponds to gravity modes and shorter periods to acoustic modes, respectively. Using a 1-D stratified velocity model of the atmosphere we show that linear acoustic ray tracing fits arrival times at all GPS receivers. We interpret the perturbation as a direct acoustic wave caused by the explosion itself. This study shows that even relatively small subsurface

  1. RESEARCH PAPERS : Ionospheric signature of surface mine blasts from Global Positioning System measurements

    NASA Astrophysics Data System (ADS)

    Calais, Eric; Bernard Minster, J.; Hofton, Michelle; Hedlin, Michael

    1998-01-01

    Sources such as atmospheric or buried explosions and shallow earthquakes are known to produce infrasonic pressure waves in the atmosphere Because of the coupling between neutral particles and electrons at ionospheric altitudes, these acoustic and gravity waves induce variations of the ionospheric electron density. The Global Positioning System (GPS) provides a way of directly measuring the total electron content in the ionosphere and, therefore, of detecting such perturbations in the upper atmosphere. In July and August 1996, three large surface mine blasts (1.5 Kt each) were detonated at the Black Thunder coal mine in eastern Wyoming. As part of a seismic and acoustic monitoring experiment, we deployed five dual-frequency GPS receivers at distances ranging from 50 to 200 km from the mine and were able to detect the ionospheric perturbation caused by the blasts. The perturbation starts 10 to 15 min after the blast, lasts for about 30 min, and propagates with an apparent horizontal velocity of 1200 m s- 1. Its amplitude reaches 3 × 1014 el m- 2 in the 7-3 min period band, a value close to the ionospheric perturbation caused by the M=6.7 Northridge earthquake (Calais & Minster 1995). The small signal-to-noise ratio of the perturbation can be improved by slant-stacking the electron content time-series recorded by the different GPS receivers taking into account the horizontal propagation of the perturbation. The energy of the perturbation is concentrated in the 200 to 300 s period band, a result consistent with previous observations and numerical model predictions. The 300 s band probably corresponds to gravity modes and shorter periods to acoustic modes, respectively. Using a 1-D stratified velocity model of the atmosphere we show that linear acoustic ray tracing fits arrival times at all GPS receivers. We interpret the perturbation as a direct acoustic wave caused by the explosion itself. This study shows that even relatively small subsurface events can produce

  2. Travel patterns during pregnancy: comparison between Global Positioning System (GPS) tracking and questionnaire data

    PubMed Central

    2013-01-01

    Background Maternal exposures to traffic-related air pollution have been associated with adverse pregnancy outcomes. Exposures to traffic-related air pollutants are strongly influenced by time spent near traffic. However, little is known about women’s travel activities during pregnancy and whether questionnaire-based data can provide reliable information on travel patterns during pregnancy. Objectives Examine women’s in-vehicle travel behavior during pregnancy and examine the difference in travel data collected by questionnaire and global positioning system (GPS) and their potential for exposure error. Methods We measured work-related travel patterns in 56 pregnant women using a questionnaire and one-week GPS tracking three times during pregnancy (<20 weeks, 20–30 weeks, and >30 weeks of gestation). We compared self-reported activities with GPS-derived trip distance and duration, and examined potentially influential factors that may contribute to differences. We also described in-vehicle travel behavior by pregnancy periods and influences of demographic and personal factors on daily travel times. Finally, we estimated personal exposure to particle-bound polycyclic aromatic hydrocarbon (PB-PAH) and examined the magnitude of exposure misclassification using self-reported vs. GPS travel data. Results Subjects overestimated both trip duration and trip distance compared to the GPS data. We observed moderately high correlations between self-reported and GPS-recorded travel distance (home to work trips: r = 0.88; work to home trips: r = 0.80). Better agreement was observed between the GPS and the self-reported travel time for home to work trips (r = 0.77) than work to home trips (r = 0.64). The subjects on average spent 69 and 93 minutes traveling in vehicles daily based on the GPS and self-reported data, respectively. Longer daily travel time was observed among participants in early pregnancy, and during certain pregnancy periods in women with

  3. Crustal motion in the Antarctic interior from a decade of Global Positioning System measurements

    NASA Astrophysics Data System (ADS)

    Willis, Michael J.

    A decade of Global Positioning System (GPS) data have been collected at bedrock sites in southern Victoria Land, Antarctica. Measured motions of the crust have been examined to determine if ongoing tectonic deformation occurs within the study area, across the structural boundary between East and West Antarctica. Crustal motions are used to test for activity over the offshore Terror Rift, where young faulting is documented, and to assess locally whether the active Erebus volcano deforms the crust. Bedrock motions caused by large scale ice-mass changes that have occurred in the area since the Last Glacial Maximum are also a major focus of the study. The horizontal GPS motions record Antarctic plate motion of ˜15 mm/yr to the southeast. No deformation is observed over the Transantarctic Mountains Front Zone. Very small amounts of deformation are observed along the Terror Rift, however the recorded direction of motions may be the result of Glacial Isostatic Adjustment (GIA), rather than active tectonics. Recorded motions observed to the south of Ross Island suggest that the Terror Rift continues beneath the Ross Ice Shelf. No volcanic loading signal is observed. Vertical crustal motions exhibit a down-to-the-east tilt over the study area. A suite of earth models, including more than three hundred different mantle viscosity profiles, three different lithospheric thicknesses and three different ice histories, were used to model uplift due to Glacial Isostatic Adjustment driven by ice mass change. None replicate the observed tilt. Two Relative Sea Level curves for the region also could not be replicated by GIA models examined. Comparison of GPS vertical velocities and our GIA models produce well-constrained earth models for the study area, but suggest that current ice history models for the region must be revised to replicate measured crustal motions. We compare the output of our GPS-constrained models with published crustal uplift rates used in modern ice mass balance

  4. Evaluation of Point Positioning Using the Global Positioning System and the Quasi-Zenith Satellite System as Measured from South Korea

    NASA Astrophysics Data System (ADS)

    Choi, Byung-Kyu; Cho, Chang-Hyun; Cho, Jung Ho

    2015-12-01

    The Quasi-Zenith Satellite System (QZSS), a dedicated regional Japanese satellite system currently under development, was designed to complement the performance of the Global Positioning System (GPS). The high elevation angle of the QZSS satellite is expected to enhance the effectiveness of GPS in urban environments. Thus, the work described in this paper, aimed to investigate the effect of QZSS on GPS performance, by processing the GPS and QZSS measurements recorded at the Bohyunsan reference station in South Korea. We used these data, to evaluate the satellite visibility, carrier-to-noise density (C/No), performance of single point positioning, and Dilution of Precision (DOP). The QZSS satellite is currently available over South Korea for 19 hours at an elevation angle of more than 10 degrees. The results showed that the impact of the QZSS on users' vertical positioning is greatest when the satellite is above 80 degrees of elevation. As for Precise Point Positioning (PPP) performance, the combined GPS/QZSS kinematic PPP was found to improve the positioning accuracy compared to the GPS only kinematic PPP.

  5. Photogrammetric and Global Positioning System Measurements of Active Pahoehoe Lava Lobe Emplacement on Kilauea, Hawaii

    NASA Technical Reports Server (NTRS)

    Hamilton, Christopher W.; Glaze, Lori S.; James, Mike R.; Baloga, Stephen M.; Fagents, Sarah A.

    2012-01-01

    Basalt is the most common rock type on the surface of terrestrial bodies throughout the solar system and -- by total volume and areal coverage -- pahoehoe flows are the most abundant form of basaltic lava in subaerial and submarine environments on Earth. A detailed understanding of pahoehoe emplacement processes is necessary for developing accurate models of flow field development, assessing hazards associated with active lava flows, and interpreting the significance of lava flow morphology on Earth and other planetary bodies. Here, we examine the active emplacement of pahoehoe lobes along the margins of the Hook Flow from Pu'u 'O'o on Kilauea, Hawaii. Topographic data were acquired between 21 and 23 February 2006 using stereo-imaging and differential global positing system (DGPS) measurements. During this time, the average discharge rate for the Hook Flow was 0.01-0.05 cubic m/s. Using stereogrammetric point clouds and interpolated digital terrain models (DTMs), active flow fronts were digitized at 1 minute intervals. These areal spreading maps show that the lava lobe grew by a series of breakouts tha t broadly fit into two categories: narrow (0.2-0.6 m-wide) toes that grew preferentially down-slope, and broad (1.4-3.5 m-wide) breakouts that formed along the sides of the lobe, nearly perpendicular to the down-flow axis. These lobes inflated to half of their final thickness within approx 5 minutes, with a rate of inflation that generally deceased with time. Through a combination of down-slope and cross-slope breakouts, lobes developed a parabolic cross-sectional shape within tens of minutes. We also observed that while the average local discharge rate for the lobe was generally constant at 0.0064 +/- 0.0019 cubic m/s, there was a 2 to 6 fold increase in the areal coverage rate every 4.1 +/- 0.6 minutes. We attribute this periodicity to the time required for the dynamic pressurization of the liquid core of the lava lobe to exceed the cooling-induced strength of the

  6. International Accreditation as Global Position Taking: An Empirical Exploration of U.S. Accreditation in Mexico

    ERIC Educational Resources Information Center

    Blanco Ramírez, Gerardo

    2015-01-01

    Institutional accreditation in higher education holds universities accountable through external evaluation; at the same time, accreditation constitutes an opportunity for higher education leaders to demonstrate the quality of their institutions. In an increasingly global field of higher education, in which quality practices become diffused across…

  7. Global Citizens/Local Agents: Re-positioning the School at the Centre of Sociocultural Transformation.

    ERIC Educational Resources Information Center

    Gill, Judy; Howard, Sue

    For Australians the issue of globalization adds a new dimension to the complex of concerns around questions of national identity. This year has seen wide coverage of issues of citizenship and the rules whereby entry of refugees is permitted. Yet another indication of growing concern at the way Australia is understood came through educational…

  8. MTV's "Staying Alive" Global Campaign Promoted Interpersonal Communication about HIV and Positive Beliefs about HIV Prevention

    ERIC Educational Resources Information Center

    Geary, Cynthia Waszak; Burke; Holly McClain; Castelnau, Laure; Neupane; Shailes; Sall, Yacine Ba; Wong, Emily; Tucker, Heidi Toms

    2007-01-01

    In 2002 MTV launched a global multicomponent HIV prevention campaign, "Staying Alive," reaching over 166 countries worldwide. An evaluation of this campaign focused on three diverse sites: Kathmandu, Nepal; Sao Paulo, Brazil; and Dakar, Senegal. Data were collected before and after campaign implementation through population-based household…

  9. Real-Time Point Positioning Performance Evaluation of Single-Frequency Receivers Using NASA's Global Differential GPS System

    NASA Technical Reports Server (NTRS)

    Muellerschoen, Ronald J.; Iijima, Byron; Meyer, Robert; Bar-Sever, Yoaz; Accad, Elie

    2004-01-01

    This paper evaluates the performance of a single-frequency receiver using the 1-Hz differential corrections as provided by NASA's global differential GPS system. While the dual-frequency user has the ability to eliminate the ionosphere error by taking a linear combination of observables, the single-frequency user must remove or calibrate this error by other means. To remove the ionosphere error we take advantage of the fact that the magnitude of the group delay in range observable and the carrier phase advance have the same magnitude but are opposite in sign. A way to calibrate this error is to use a real-time database of grid points computed by JPL's RTI (Real-Time Ionosphere) software. In both cases we evaluate the positional accuracy of a kinematic carrier phase based point positioning method on a global extent.

  10. Breast or bottle? HIV-positive women's responses to global health policy on infant feeding in India.

    PubMed

    Van Hollen, Cecilia

    2011-12-01

    This article describes how local responses to global health initiatives on infant feeding for HIV-positive mothers reflect and transform sociocultural values in Tamil Nadu, India. Drawing from ethnographic research conducted from 2002 to 2008, the article compares guidelines for counseling HIV-positive mothers established by UNICEF and WHO with decision-making processes and perceptions of HIV-positive mothers. In addition to the financial considerations, three factors are identified as impinging on this decision: (1) a strong sociocultural value in favor of breastfeeding linked to historical traditions and contemporary state and international development discourses, (2) constructions of class identity, (3) the influence of a rights-based discourse in HIV/AIDS advocacy. This wide range of factors points to the difficulty of implementing the international protocols. This is the first study of its kind to closely examine the complex determinants in HIV-positive women's decisions and evaluations of infant feeding methods in India.

  11. Global Positioning System surveys of storm-surge sensors deployed during Hurricane Ike, Seadrift, Texas, to Lake Charles, Louisiana, 2008

    USGS Publications Warehouse

    Payne, Jason D.; Woodward, Brenda K.; Storm, John B.

    2009-01-01

    The U.S. Geological Survey installed a network of pressure sensors at 65 sites along the Gulf Coast from Seadrift, Texas, northeast to Lake Charles, Louisiana, to record the timing, areal extent, and magnitude of inland storm surge and coastal flooding caused by Hurricane Ike in September 2008. A Global Positioning System was used to obtain elevations of reference marks near each sensor. A combination of real-time kinematic (RTK) and static Global Positioning System surveys were done to obtain elevations of reference marks. Leveling relative to reference marks was done to obtain elevations of sensor orifices above the reference marks. This report summarizes the Global Positioning System data collected and processed to obtain reference mark and storm-sensor-orifice elevations for 59 storm-surge sensors recovered from the original 65 installed as a necessary prelude to computation of storm-surge elevations. National Geodetic Survey benchmarks were used for RTK surveying. Where National Geodetic Survey benchmarks were not within 12 kilometers of a sensor site, static surveying was done. Additional control points for static surveying were in the form of newly established benchmarks or reestablished existing benchmarks. RTK surveying was used to obtain positions and elevations of reference marks for 29 sensor sites. Static surveying was used to obtain positions and elevations of reference marks for 34 sensor sites; four sites were surveyed using both methods. Multiple quality checks on the RTK-survey and static-survey data were applied. The results of all quality checks indicate that the desired elevation accuracy for the surveys of this report, less than 0.1-meter error, was achieved.

  12. Strongly-motivated positive affects induce faster responses to local than global information of visual stimuli: an approach using large-size Navon letters.

    PubMed

    Noguchi, Yasuki; Tomoike, Kouta

    2016-01-12

    Recent studies argue that strongly-motivated positive emotions (e.g. desire) narrow a scope of attention. This argument is mainly based on an observation that, while humans normally respond faster to global than local information of a visual stimulus (global advantage), positive affects eliminated the global advantage by selectively speeding responses to local (but not global) information. In other words, narrowing of attentional scope was indirectly evidenced by the elimination of global advantage (the same speed of processing between global and local information). No study has directly shown that strongly-motivated positive affects induce faster responses to local than global information while excluding a bias for global information (global advantage) in a baseline (emotionally-neutral) condition. In the present study, we addressed this issue by eliminating the global advantage in a baseline (neutral) state. Induction of positive affects under this state resulted in faster responses to local than global information. Our results provided direct evidence that positive affects in high motivational intensity narrow a scope of attention.

  13. Global trophic position comparison of two dominant mesopelagic fish families (Myctophidae, Stomiidae) using amino acid nitrogen isotopic analyses

    USGS Publications Warehouse

    Choy, C. Anela; Davison, Peter C.; Drazen, Jeffrey C.; Flynn, Adrian; Gier, Elizabeth J.; Hoffman, Joel C.; McClain-Counts, Jennifer P.; Miller, Todd W.; Popp, Brian N.; Ross, Steve W.; Sutton, Tracey T.

    2012-01-01

    The δ15N values of organisms are commonly used across diverse ecosystems to estimate trophic position and infer trophic connectivity. We undertook a novel cross-basin comparison of trophic position in two ecologically well-characterized and different groups of dominant mid-water fish consumers using amino acid nitrogen isotope compositions. We found that trophic positions estimated from the δ15N values of individual amino acids are nearly uniform within both families of these fishes across five global regions despite great variability in bulk tissue δ15N values. Regional differences in the δ15N values of phenylalanine confirmed that bulk tissue δ15N values reflect region-specific water mass biogeochemistry controlling δ15N values at the base of the food web. Trophic positions calculated from amino acid isotopic analyses (AA-TP) for lanternfishes (family Myctophidae) (AA-TP ~2.9) largely align with expectations from stomach content studies (TP ~3.2), while AA-TPs for dragonfishes (family Stomiidae) (AA-TP ~3.2) were lower than TPs derived from stomach content studies (TP~4.1). We demonstrate that amino acid nitrogen isotope analysis can overcome shortcomings of bulk tissue isotope analysis across biogeochemically distinct systems to provide globally comparative information regarding marine food web structure.

  14. Global Trophic Position Comparison of Two Dominant Mesopelagic Fish Families (Myctophidae, Stomiidae) Using Amino Acid Nitrogen Isotopic Analyses

    PubMed Central

    Choy, C. Anela; Davison, Peter C.; Drazen, Jeffrey C.; Flynn, Adrian; Gier, Elizabeth J.; Hoffman, Joel C.; McClain-Counts, Jennifer P.; Miller, Todd W.; Popp, Brian N.; Ross, Steve W.; Sutton, Tracey T.

    2012-01-01

    The δ15N values of organisms are commonly used across diverse ecosystems to estimate trophic position and infer trophic connectivity. We undertook a novel cross-basin comparison of trophic position in two ecologically well-characterized and different groups of dominant mid-water fish consumers using amino acid nitrogen isotope compositions. We found that trophic positions estimated from the δ15N values of individual amino acids are nearly uniform within both families of these fishes across five global regions despite great variability in bulk tissue δ15N values. Regional differences in the δ15N values of phenylalanine confirmed that bulk tissue δ15N values reflect region-specific water mass biogeochemistry controlling δ15N values at the base of the food web. Trophic positions calculated from amino acid isotopic analyses (AA-TP) for lanternfishes (family Myctophidae) (AA-TP ∼2.9) largely align with expectations from stomach content studies (TP ∼3.2), while AA-TPs for dragonfishes (family Stomiidae) (AA-TP ∼3.2) were lower than TPs derived from stomach content studies (TP∼4.1). We demonstrate that amino acid nitrogen isotope analysis can overcome shortcomings of bulk tissue isotope analysis across biogeochemically distinct systems to provide globally comparative information regarding marine food web structure. PMID:23209656

  15. The sustainable management and protection of forests: analysis of the current position globally.

    PubMed

    Freer-Smith, Peter; Carnus, Jean-Michel

    2008-06-01

    The loss of forest area globally due to change of land use, the importance of forests in the conservation of biodiversity and in carbon and other biogeochemical cycles, together with the threat to forests from pollution and from the impacts of climate change, place forestry policy and practice at the center of global environmental and sustainability strategy. Forests provide important economic, environmental, social, and cultural benefits, so that in forestry, as in other areas of environmental policy and management, there are tensions between economic development and environmental protection. In this article we review the current information on global forest cover and condition, examine the international processes that relate to forest protection and to sustainable forest management, and look at the main forest certification schemes. We consider the link between the international processes and certification schemes and also their combined effectiveness. We conclude that in some regions of the world neither mechanism is achieving forest protection, while in others local or regional implementation is occurring and is having a significant impact. Choice of certification scheme and implementation of management standards are often influenced by a consideration of the associated costs, and there are some major issues over the monitoring of agreed actions and of the criteria and indicators of sustainability. There are currently a number of initiatives seeking to improve the operation of the international forestry framework (e.g., The Montreal Process, the Ministerial Convention of the Protection of Forests in Europe and European Union actions in Europe, the African Timber Organisation and International Tropical Timber Organisation initiative for African tropical forest, and the development of a worldwide voluntary agreement on forestry in the United Nations Forum on Forests). We suggest that there is a need to improve the connections between scientific understanding

  16. Multi-Unmanned Aerial Vehicle (UAV) Cooperative Fault Detection Employing Differential Global Positioning (DGPS), Inertial and Vision Sensors.

    PubMed

    Heredia, Guillermo; Caballero, Fernando; Maza, Iván; Merino, Luis; Viguria, Antidio; Ollero, Aníbal

    2009-01-01

    This paper presents a method to increase the reliability of Unmanned Aerial Vehicle (UAV) sensor Fault Detection and Identification (FDI) in a multi-UAV context. Differential Global Positioning System (DGPS) and inertial sensors are used for sensor FDI in each UAV. The method uses additional position estimations that augment individual UAV FDI system. These additional estimations are obtained using images from the same planar scene taken from two different UAVs. Since accuracy and noise level of the estimation depends on several factors, dynamic replanning of the multi-UAV team can be used to obtain a better estimation in case of faults caused by slow growing errors of absolute position estimation that cannot be detected by using local FDI in the UAVs. Experimental results with data from two real UAVs are also presented.

  17. Multi-Unmanned Aerial Vehicle (UAV) Cooperative Fault Detection Employing Differential Global Positioning (DGPS), Inertial and Vision Sensors

    PubMed Central

    Heredia, Guillermo; Caballero, Fernando; Maza, Iván; Merino, Luis; Viguria, Antidio; Ollero, Aníbal

    2009-01-01

    This paper presents a method to increase the reliability of Unmanned Aerial Vehicle (UAV) sensor Fault Detection and Identification (FDI) in a multi-UAV context. Differential Global Positioning System (DGPS) and inertial sensors are used for sensor FDI in each UAV. The method uses additional position estimations that augment individual UAV FDI system. These additional estimations are obtained using images from the same planar scene taken from two different UAVs. Since accuracy and noise level of the estimation depends on several factors, dynamic replanning of the multi-UAV team can be used to obtain a better estimation in case of faults caused by slow growing errors of absolute position estimation that cannot be detected by using local FDI in the UAVs. Experimental results with data from two real UAVs are also presented. PMID:22400008

  18. Application of global positioning system to determination of tectonic plate movements and crustal deformations

    NASA Technical Reports Server (NTRS)

    Anderle, R. J.

    1978-01-01

    It is shown that pseudo-range measurements to four GPS satellites based on correlation of the pseudo random code transmissions from the satellites can be used to determine the relative position of ground stations which are separated by several hundred kilometers to a precision at the centimeter level. Carrier signal measurements during the course of passage of satellites over a pair of stations also yield centimeter precision in the relative position, but oscillator instabilities limit the accuracy. The accuracy of solutions based on either type of data is limited by unmodeled tropospheric refraction effects which would reach 5 centimeters at low elevation angles for widely separated stations.

  19. Geocenter location and variations in earth orientation using global positioning system measurements

    NASA Technical Reports Server (NTRS)

    Malla, R. P.; Wu, S. C.; Lichten, S. M.

    1993-01-01

    We have studied the use of GPS ground and flight tracking data to measure short-period earth orientation variations and changes in geocenter location. Comparisons between GPS-estimated earth rotation variations and those calculated from ocean tide models suggest that observed subdaily variations in earth rotation are dominated by oceanic tidal effects. Our preliminary GPS estimates for geocenter location agree with an independent satellite laser ranging estimates to 10-15 cm. Covariance analysis predicts that temporal resolution of GPS estimates for earth orientation and geocenter improves significantly when data collected from low earth-orbiting satellites as well as from ground sites are combined. The low-earth GPS tracking data enhance the accuracy and resolution for measuring high-frequency global geodynamical signals over time scales less than 1 day.

  20. Kidney Disease: Improving Global Outcomes guidelines on anaemia management in chronic kidney disease: a European Renal Best Practice position statement.

    PubMed

    Locatelli, Francesco; Bárány, Peter; Covic, Adrian; De Francisco, Angel; Del Vecchio, Lucia; Goldsmith, David; Hörl, Walter; London, Gerard; Vanholder, Raymond; Van Biesen, Wim

    2013-06-01

    Recently, the Kidney Disease: Improving Global Outcomes (KDIGO) group has produced comprehensive clinical practice guidelines for the management of anaemia in CKD patients. These guidelines addressed all of the important points related to anaemia management in CKD patients, including therapy with erythropoieis stimulating agents (ESA), iron therapy, ESA resistance and blood transfusion use. Because most guidelines were 'soft' rather than 'strong', and because global guidelines need to be adapted and implemented into the regional context where they are used, on behalf of the European Renal Best Practice Advisory Board some of its members, and other external experts in this field, who were not participants in the KDIGO guidelines group, were invited to participate in this anaemia working group to examine and comment on the KDIGO documents in this position paper. In this article, the group concentrated only on those guidelines which we considered worth amending or adapting. All guidelines not specifically mentioned are fully endorsed.

  1. Isotonic Modeling with Non-Differentiable Loss Functions with Application to Lasso Regularization.

    PubMed

    Painsky, Amichai; Rosset, Saharon

    2016-02-01

    In this paper we present an algorithmic approach for fitting isotonic models under convex, yet non-differentiable, loss functions. It is a generalization of the greedy non-regret approach proposed by Luss and Rosset (2014) for differentiable loss functions, taking into account the sub-gradiental extensions required. We prove that our suggested algorithm solves the isotonic modeling problem while maintaining favorable computational and statistical properties. As our suggested algorithm may be used for any non-differentiable loss function, we focus our interest on isotonic modeling for either regression or two-class classification with appropriate log-likelihood loss and lasso penalty on the fitted values. This combination allows us to maintain the non-parametric nature of isotonic modeling, while controlling model complexity through regularization. We demonstrate the efficiency and usefulness of this approach on both synthetic and real world data. An implementation of our suggested solution is publicly available from the first author's website (https://sites.google.com/site/amichaipainsky/software).

  2. Global signal modulation of single-trial fMRI response variability: Effect on positive vs negative BOLD response relationship.

    PubMed

    Mayhew, S D; Mullinger, K J; Ostwald, D; Porcaro, C; Bowtell, R; Bagshaw, A P; Francis, S T

    2016-06-01

    In functional magnetic resonance imaging (fMRI), the relationship between positive BOLD responses (PBRs) and negative BOLD responses (NBRs) to stimulation is potentially informative about the balance of excitatory and inhibitory brain responses in sensory cortex. In this study, we performed three separate experiments delivering visual, motor or somatosensory stimulation unilaterally, to one side of the sensory field, to induce PBR and NBR in opposite brain hemispheres. We then assessed the relationship between the evoked amplitudes of contralateral PBR and ipsilateral NBR at the level of both single-trial and average responses. We measure single-trial PBR and NBR peak amplitudes from individual time-courses, and show that they were positively correlated in all experiments. In contrast, in the average response across trials the absolute magnitudes of both PBR and NBR increased with increasing stimulus intensity, resulting in a negative correlation between mean response amplitudes. Subsequent analysis showed that the amplitude of single-trial PBR was positively correlated with the BOLD response across all grey-matter voxels and was not specifically related to the ipsilateral sensory cortical response. We demonstrate that the global component of this single-trial response modulation could be fully explained by voxel-wise vascular reactivity, the BOLD signal standard deviation measured in a separate resting-state scan (resting state fluctuation amplitude, RSFA). However, bilateral positive correlation between PBR and NBR regions remained. We further report that modulations in the global brain fMRI signal cannot fully account for this positive PBR-NBR coupling and conclude that the local sensory network response reflects a combination of superimposed vascular and neuronal signals. More detailed quantification of physiological and noise contributions to the BOLD signal is required to fully understand the trial-by-trial PBR and NBR relationship compared with that of

  3. Global signal modulation of single-trial fMRI response variability: Effect on positive vs negative BOLD response relationship.

    PubMed

    Mayhew, S D; Mullinger, K J; Ostwald, D; Porcaro, C; Bowtell, R; Bagshaw, A P; Francis, S T

    2016-06-01

    In functional magnetic resonance imaging (fMRI), the relationship between positive BOLD responses (PBRs) and negative BOLD responses (NBRs) to stimulation is potentially informative about the balance of excitatory and inhibitory brain responses in sensory cortex. In this study, we performed three separate experiments delivering visual, motor or somatosensory stimulation unilaterally, to one side of the sensory field, to induce PBR and NBR in opposite brain hemispheres. We then assessed the relationship between the evoked amplitudes of contralateral PBR and ipsilateral NBR at the level of both single-trial and average responses. We measure single-trial PBR and NBR peak amplitudes from individual time-courses, and show that they were positively correlated in all experiments. In contrast, in the average response across trials the absolute magnitudes of both PBR and NBR increased with increasing stimulus intensity, resulting in a negative correlation between mean response amplitudes. Subsequent analysis showed that the amplitude of single-trial PBR was positively correlated with the BOLD response across all grey-matter voxels and was not specifically related to the ipsilateral sensory cortical response. We demonstrate that the global component of this single-trial response modulation could be fully explained by voxel-wise vascular reactivity, the BOLD signal standard deviation measured in a separate resting-state scan (resting state fluctuation amplitude, RSFA). However, bilateral positive correlation between PBR and NBR regions remained. We further report that modulations in the global brain fMRI signal cannot fully account for this positive PBR-NBR coupling and conclude that the local sensory network response reflects a combination of superimposed vascular and neuronal signals. More detailed quantification of physiological and noise contributions to the BOLD signal is required to fully understand the trial-by-trial PBR and NBR relationship compared with that of

  4. Differential Global Positioning System for the Surface-Towed Ordnance Locating System: Testing, results, and user`s guide

    SciTech Connect

    Stewart, T.L.; Hubbard, C.W.

    1993-10-01

    Researchers at Pacific Northwest Laboratory integrated and tested a Global Positioning System (GPS) for use with the Naval Explosive Ordnance Disposal Technology Center`s (NEODTC) Surface-Towed Ordnance Locating System (STOLS). The GPS automatically and continuously provides latitude, longitude, and elevation information at the mobile GPS unit. The results of testing the GPS are shown in this report. The results reveal accuracies in the submeter range in real time and within a few centimeters using post-processing software. A description of hardware and software components is also included, along with system drawings and parts lists.

  5. The dynamics of global positioning system orbits and the determination of precise ephemerides

    NASA Technical Reports Server (NTRS)

    Colombo, Oscar L.

    1989-01-01

    The suggestion made on the basis of the analytical orbit perturbation theory that the errors in the ephemerides of the GPS satellites are due mostly to resonant effects that can be corrected by adjusting a few parameters in a empirical acceleration formula is tested using simulations and actual data analysis. Data from the Spring 1985 Experiment were used to calculate improved ephemerides, and these ephemerides were used in the estimation of the coordinates of GPS stations within the continental United States, previously positioned with VLBI. The results of this test support the idea that the errors are mostly of a resonant nature and can be corrected.

  6. Global gravity field models from the GPS positions of CHAMP, GRACE and GOCE satellites

    NASA Astrophysics Data System (ADS)

    Bezděk, A.; Sebera, J.; Klokočník, J.; Kostelecký, J.

    2012-04-01

    The aim of our work is to generate Earth's gravity field models from the GPS positions of low Earth orbiters. We will present our inversion method and numerical results based on the real-world data of CHAMP, GRACE and GOCE satellites. The presented inversion method is based on Newton's second law of motion, which relates the observed acceleration of the satellite with the forces acting on it. The vector of the observed acceleration is obtained through a numerical second-derivative filter applied to the time series of the kinematic positions. Forces other than those due to the geopotential are either modelled (lunisolar perturbations, tides) or provided by the onboard measurements (nongravitational perturbations). Then the observation equations are formulated using the gradient of the spherical harmonic expansion of the geopotential. From this linear system the harmonic coefficients are directly obtained. We do not use any a priori gravity field model. Although the basic scheme of the acceleration approach is straightforward, the implementation details play a crucial role in obtaining reasonable results. The numerical derivative of noisy data (here the GPS positions) strongly amplifies the high frequency noise and creates autocorrelation in the observation errors. We successfully solve both of these problems by using the generalized least squares method, which defines a linear transformation of the observation equations. In the transformed variables the errors become uncorrelated, so the ordinary least squares estimation may be used to find the regression parameters with correct estimates of their uncertainties. The digital filter of the second derivative is an approximation to the analytical operation. We will show how different the results might be depending on the particular choice of the parameters defining the filter. Another problem is the correlation of the errors in the GPS positions. Here we use the tools from time series analysis. The systematic behaviour

  7. Global health and climate change: moving from denial and catastrophic fatalism to positive action.

    PubMed

    Costello, Anthony; Maslin, Mark; Montgomery, Hugh; Johnson, Anne M; Ekins, Paul

    2011-05-13

    The health effects of climate change have had relatively little attention from climate scientists and governments. Climate change will be a major threat to population health in the current century through its potential effects on communicable disease, heat stress, food and water security, extreme weather events, vulnerable shelter and population migration. This paper addresses three health-sector strategies to manage the health effects of climate change-promotion of mitigation, tackling the pathways that lead to ill-health and strengthening health systems. Mitigation of greenhouse gas (GHG) emissions is affordable, and low-carbon technologies are available now or will be in the near future. Pathways to ill-health can be managed through better information, poverty reduction, technological innovation, social and cultural change and greater coordination of national and international institutions. Strengthening health systems requires increased investment in order to provide effective public health responses to climate-induced threats to health, equitable treatment of illness, promotion of low-carbon lifestyles and renewable energy solutions within health facilities. Mitigation and adaptation strategies will produce substantial benefits for health, such as reductions in obesity and heart disease, diabetes, stress and depression, pneumonia and asthma, as well as potential cost savings within the health sector. The case for mitigating climate change by reducing GHGs is overwhelming. The need to build population resilience to the global health threat from already unavoidable climate change is real and urgent. Action must not be delayed by contrarians, nor by catastrophic fatalists who say it is all too late.

  8. Precise positioning with current multi-constellation Global Navigation Satellite Systems: GPS, GLONASS, Galileo and BeiDou.

    PubMed

    Li, Xingxing; Zhang, Xiaohong; Ren, Xiaodong; Fritsche, Mathias; Wickert, Jens; Schuh, Harald

    2015-01-01

    The world of satellite navigation is undergoing dramatic changes with the rapid development of multi-constellation Global Navigation Satellite Systems (GNSSs). At the moment more than 70 satellites are already in view, and about 120 satellites will be available once all four systems (BeiDou + Galileo + GLONASS + GPS) are fully deployed in the next few years. This will bring great opportunities and challenges for both scientific and engineering applications. In this paper we develop a four-system positioning model to make full use of all available observations from different GNSSs. The significant improvement of satellite visibility, spatial geometry, dilution of precision, convergence, accuracy, continuity and reliability that a combining utilization of multi-GNSS brings to precise positioning are carefully analyzed and evaluated, especially in constrained environments. PMID:25659949

  9. Precise positioning with current multi-constellation Global Navigation Satellite Systems: GPS, GLONASS, Galileo and BeiDou

    PubMed Central

    Li, Xingxing; Zhang, Xiaohong; Ren, Xiaodong; Fritsche, Mathias; Wickert, Jens; Schuh, Harald

    2015-01-01

    The world of satellite navigation is undergoing dramatic changes with the rapid development of multi-constellation Global Navigation Satellite Systems (GNSSs). At the moment more than 70 satellites are already in view, and about 120 satellites will be available once all four systems (BeiDou + Galileo + GLONASS + GPS) are fully deployed in the next few years. This will bring great opportunities and challenges for both scientific and engineering applications. In this paper we develop a four-system positioning model to make full use of all available observations from different GNSSs. The significant improvement of satellite visibility, spatial geometry, dilution of precision, convergence, accuracy, continuity and reliability that a combining utilization of multi-GNSS brings to precise positioning are carefully analyzed and evaluated, especially in constrained environments. PMID:25659949

  10. Visual-based simultaneous localization and mapping and global positioning system correction for geo-localization of a mobile robot

    NASA Astrophysics Data System (ADS)

    Berrabah, Sid Ahmed; Sahli, Hichem; Baudoin, Yvan

    2011-12-01

    This paper introduces an approach combining visual-based simultaneous localization and mapping (V-SLAM) and global positioning system (GPS) correction for accurate multi-sensor localization of an outdoor mobile robot in geo-referenced maps. The proposed framework combines two extended Kalman filters (EKF); the first one, referred to as the integration filter, is dedicated to the improvement of the GPS localization based on data from an inertial navigation system and wheels' encoders. The second EKF implements the V-SLAM process. The linear and angular velocities in the dynamic model of the V-SLAM EKF filter are given by the GPS/INS/Encoders integration filter. On the other hand, the output of the V-SLAM EKF filter is used to update the dynamics estimation in the integration filter and therefore the geo-referenced localization. This solution increases the accuracy and the robustness of the positioning during GPS outage and allows SLAM in less featured environments.

  11. Precise positioning with current multi-constellation Global Navigation Satellite Systems: GPS, GLONASS, Galileo and BeiDou.

    PubMed

    Li, Xingxing; Zhang, Xiaohong; Ren, Xiaodong; Fritsche, Mathias; Wickert, Jens; Schuh, Harald

    2015-02-09

    The world of satellite navigation is undergoing dramatic changes with the rapid development of multi-constellation Global Navigation Satellite Systems (GNSSs). At the moment more than 70 satellites are already in view, and about 120 satellites will be available once all four systems (BeiDou + Galileo + GLONASS + GPS) are fully deployed in the next few years. This will bring great opportunities and challenges for both scientific and engineering applications. In this paper we develop a four-system positioning model to make full use of all available observations from different GNSSs. The significant improvement of satellite visibility, spatial geometry, dilution of precision, convergence, accuracy, continuity and reliability that a combining utilization of multi-GNSS brings to precise positioning are carefully analyzed and evaluated, especially in constrained environments.

  12. Global evidence of positive impacts of freshwater biodiversity on fishery yields

    PubMed Central

    Holland, Robert Alan; Darwall, William Robert Thomas; Eigenbrod, Felix; Tittensor, Derek

    2016-01-01

    need for more data to fully understand and monitor the contribution of biodiversity to inland fisheries globally. PMID:27587980

  13. Using the global positioning system in support of environmental characterization at the Hanford Site in Washington State

    SciTech Connect

    Peterson, L.B.; Tzemos, S.; Dietz, L.A.

    1993-10-01

    The US Department of Energy`s 1,450 km{sup 2} Hanford Site in southeastern Washington State accumulated hazardous wastes for more than 50 years. To support the Site`s mission of environmental restoration and cleanup, the Global Positioning System (GPS) is being used to verify waste site locations and provide location information for field samples. Collected GPS data are stored for use in the Hanford Geographic Information System (HGIS). The NAVSTAR GPS is a space-based electronic navigation and positioning system designed and operated by the US Department of Defense (DOD). The system consists of three major components: (1) the space segment, comprising 24 earth-orbiting satellites; (2) the control segment, made up of 5 control and monitoring stations placed around the globe; and (3) the user segment, which includes users worldwide. When declared fully operational by the DOD, the NAVSTAR GPS will allow users to identify their geographical position anywhere on earth at any time. There are no user fees for the service and anyone with a GPS receiver may use the system worldwide. The one major hindrance to the system is the DOD policy concerning a security option called Selective Availability (SA). Selective Availability affects the usability of the system by intentional manipulation of the GPS signals to degrade the accuracy of the user`s positions. The period and magnitude of degradation is solely a DOD privilege. The DOD policy on SA is to vary the error in position calculated from the Standard Positioning Service code to approximately 100 m root-mean squared (RMS). With SA on and other possible errors included, users may know their location to within a few hundred meters. While this accuracy is good for many applications, it is too inaccurate for others.

  14. Global positioning system technology (GPS) for psychological research: a test of convergent and nomological validity.

    PubMed

    Wolf, Pedro S A; Figueredo, Aurelio J; Jacobs, W Jake

    2013-01-01

    The purpose of this paper is to examine the convergent and nomological validity of a GPS-based measure of daily activity, operationalized as Number of Places Visited (NPV). Relations among the GPS-based measure and two self-report measures of NPV, as well as relations among NPV and two factors made up of self-reported individual differences were examined. The first factor was composed of variables related to an Active Lifestyle (AL) (e.g., positive affect, extraversion…) and the second factor was composed of variables related to a Sedentary Lifestyle (SL) (e.g., depression, neuroticism…). NPV was measured over 4 days. This timeframe was made up of two week and two weekend days. A bi-variate analysis established one level of convergent validity and a Split-Plot GLM examined convergent validity, nomological validity, and alternative hypotheses related to constraints on activity throughout the week simultaneously. The first analysis revealed significant correlations among NPV measures- weekday, weekend, and the entire 4-day time period, supporting the convergent validity of the Diary-, Google Maps-, and GPS-NPV measures. Results from the second analysis, indicating non-significant mean differences in NPV regardless of method, also support this conclusion. We also found that AL is a statistically significant predictor of NPV no matter how NPV was measured. We did not find a statically significant relation among NPV and SL. These results permit us to infer that the GPS-based NPV measure has convergent and nomological validity.

  15. HPR1 encodes a global positive regulator of transcription in Saccharomyces cerevisiae.

    PubMed Central

    Zhu, Y; Peterson, C L; Christman, M F

    1995-01-01

    The Hpr1 protein has an unknown function, although it contains a region of homology to DNA topoisomerase I. We have found that hpr1 null mutants are defective in the transcription of many physiologically unrelated genes, including GAL1, HO, ADH1, and SUC2, by using a combination of Northern (RNA) blot analysis, primer extension, and upstream activation sequence-lacZ fusions. Many of the genes positively regulated by HPR1 also require SWI1, SWI2-SNF2, SWI3, SNF5, and SNF6. The transcriptional defect at HO and the CCB::lacZ upstream activation sequence in hpr1 mutants is partially suppressed by a deletion of SIN1, which encodes an HMG1p-like protein. Elevated gene dosage of either histones H3 and H4 or H2A and H2B results in a severe growth defect in combination with an hpr1 null mutation. However, increased gene dosage of all four histones simultaneously restores near-normal growth in hpr1 mutants. Altered in vivo Dam methylase sensitivity is observed at two HPR1-dependent promoters (GAL1 and SUC2). Most of the Hpr1 protein present in the cell is in a large complex (10(6) Da) that is distinct from the SWI-SNF protein complex. We propose that HPR1 affects transcription and recombination by altering chromatin structure. PMID:7862161

  16. Simultaneous Global Positioning System and radar observations of equatorial spread F at Kwajalein

    NASA Astrophysics Data System (ADS)

    Kelley, Michael C.; Hysell, David; Musman, Steven

    1996-02-01

    GPS satellites broadcast at two frequencies (L1 of 1575.42 MHz and L2 of 1227.6 MHz). The dispersive property of the ionosphere is frequently used to correct positional measurements for ionospheric effects. Independent measurements at the two frequencies can also be combined to form a relative ionospheric delay and a measure of the total electron content (TEC) which is uncertain by an additive constant. In a previous paper (Musman et al., 1990) estimates of this offset were utilized in constructing models of the time history of the equivalent zenith delay at Westford, Massachusetts. An ionospheric model composed of uniform shells whose electron density changes slowly in a typical diurnal pattern would produce relative ionospheric delays with a simple u-shaped or j-shaped curve. Most of the change in delay would be a result of changes in geometry between the observer and the satellite. Departures from a simple pattern are indicative of ionospheric disturbances and the influence of the protonosphere. From GPS data alone, it is ambiguous whether these disturbances are due to spatial structures, temporal changes, or some combination of the two. Equatorial spread F(ESF) refers to a variety of equatorial ionospheric disturbances, some of which are associated with rising plasma plumes having low electron density and a high degree of turbulence. This phenomenon occurs primarily between local sunset and local midnight at sites within about 15° of the magnetic equator. In some seasons, disturbances can occur during two out of three evenings, while at other times it can be much quieter. GPS observations at Kwajalein (9°N latitude) reported here for August 14, 1990, show severe ionospheric disruption. Two independent and simultaneous sets of radar observations confirm the presence of ESF and reveal quite a bit about the spatial and temporal conditions which affect the system. GPS observations on August 15, 1990, when no ESF was present are much quieter. We find that tens of

  17. Ground-penetrating radar and differential global positioning system data collected from Long Beach Island, New Jersey, April 2015

    USGS Publications Warehouse

    Zaremba, Nicholas J.; Smith, Kathryn E.L.; Bishop, James M.; Smith, Christopher G.

    2016-08-04

    Scientists from the United States Geological Survey, St. Petersburg Coastal and Marine Science Center, U.S. Geological Survey Pacific Coastal and Marine Science Center, and students from the University of Hawaii at Manoa collected sediment cores, sediment surface grab samples, ground-penetrating radar (GPR) and Differential Global Positioning System (DGPS) data from within the Edwin B. Forsythe National Wildlife Refuge–Holgate Unit located on the southern end of Long Beach Island, New Jersey, in April 2015 (FAN 2015-611-FA). The study’s objective was to identify washover deposits in the stratigraphic record to aid in understanding barrier island evolution. This report is an archive of GPR and DGPS data collected from Long Beach Island in 2015. Data products, including raw GPR and processed DGPS data, elevation corrected GPR profiles, and accompanying Federal Geographic Data Committee metadata can be downloaded from the Data Downloads page.

  18. Ground-penetrating radar and differential global positioning system data collected from Long Beach Island, New Jersey, April 2015

    USGS Publications Warehouse

    Zaremba, Nicholas J.; Smith, Kathryn E.L.; Bishop, James M.; Smith, Christopher G.

    2016-01-01

    Scientists from the United States Geological Survey, St. Petersburg Coastal and Marine Science Center, U.S. Geological Survey Pacific Coastal and Marine Science Center, and students from the University of Hawaii at Manoa collected sediment cores, sediment surface grab samples, ground-penetrating radar (GPR) and Differential Global Positioning System (DGPS) data from within the Edwin B. Forsythe National Wildlife Refuge–Holgate Unit located on the southern end of Long Beach Island, New Jersey, in April 2015 (FAN 2015-611-FA). The study’s objective was to identify washover deposits in the stratigraphic record to aid in understanding barrier island evolution. This report is an archive of GPR and DGPS data collected from Long Beach Island in 2015. Data products, including raw GPR and processed DGPS data, elevation corrected GPR profiles, and accompanying Federal Geographic Data Committee metadata can be downloaded from the Data Downloads page.

  19. A pilot study using global positioning systems (GPS) devices and surveys to ascertain older adults' travel patterns.

    PubMed

    Yen, Irene H; Leung, Cindy W; Lan, Mars; Sarrafzadeh, Majid; Kayekjian, Karen C; Duru, O Kenrik

    2015-04-01

    Some studies indicate that older adults lead active lives and travel to many destinations including those not in their immediate residential neighborhoods. We used global positioning system (GPS) devices to track the travel patterns of 40 older adults (mean age: 69) in San Francisco and Los Angeles. Study participants wore the GPS devices for 7 days in fall 2010 and winter 2011. We collected survey responses concurrently about travel patterns. GPS data showed a mean of four trips/day, and a mean trip distance of 7.6 km. Survey data indicated that older adults commonly made trips for four activities (e.g., volunteering, work, visiting friends) at least once each week. Older adults regularly travel outside their residential neighborhoods. GPS can document the mode of travel, the path of travel, and the destinations. Surveys can document the purpose of the travel and the impressions or experiences in the specific locations.

  20. Inequalities in Global Trade: A Cross-Country Comparison of Trade Network Position, Economic Wealth, Pollution and Mortality.

    PubMed

    Prell, Christina; Sun, Laixiang; Feng, Kuishuang; Myroniuk, Tyler W

    2015-01-01

    In this paper we investigate how structural patterns of international trade give rise to emissions inequalities across countries, and how such inequality in turn impact countries' mortality rates. We employ Multi-regional Input-Output analysis to distinguish between sulfur-dioxide (SO2) emissions produced within a country's boarders (production-based emissions) and emissions triggered by consumption in other countries (consumption-based emissions). We use social network analysis to capture countries' level of integration within the global trade network. We then apply the Prais-Winsten panel estimation technique to a panel data set across 172 countries over 20 years (1990-2010) to estimate the relationships between countries' level of integration and SO2 emissions, and the impact of trade integration and SO2 emission on mortality rates. Our findings suggest a positive, (log-) linear relationship between a country's level of integration and both kinds of emissions. In addition, although more integrated countries are mainly responsible for both forms of emissions, our findings indicate that they also tend to experience lower mortality rates. Our approach offers a unique combination of social network analysis with multiregional input-output analysis, which better operationalizes intuitive concepts about global trade and trade structure. PMID:26642202

  1. The interchangeability of global positioning system and semiautomated video-based performance data during elite soccer match play.

    PubMed

    Harley, Jamie A; Lovell, Ric J; Barnes, Christopher A; Portas, Matthew D; Weston, Matthew

    2011-08-01

    In elite-level soccer, player motion characteristics are commonly generated from match play and training situations using semiautomated video analysis systems and global positioning system (GPS) technology, respectively. Before such data are used collectively to quantify global player load, it is necessary to understand both the level of agreement and direction of bias between the systems so that specific interventions can be made based on the reported results. The aim of this report was to compare data derived from both systems for physical match performances. Six elite-level soccer players were analyzed during a competitive match using semiautomated video analysis (ProZone® [PZ]) and GPS (MinimaxX) simultaneously. Total distances (TDs), high speed running (HSR), very high speed running (VHSR), sprinting distance (SPR), and high-intensity running distance (HIR; >4.0 m·s(-1)) were reported in 15-minute match periods. The GPS reported higher values than PZ did for TD (GPS: 1,755.4 ± 245.4 m; PZ: 1,631.3 ± 239.5 m; p < 0.05); PZ reported higher values for SPR and HIR than GPS did (SPR: PZ, 34.1 ± 24.0 m; GPS: 20.3 ± 15.8 m; HIR: PZ, 368.1 ± 129.8 m; GPS: 317.0 ± 92.5 m; p < 0.05). Caution should be exercised when using match-load (PZ) and training-load (GPS) data interchangeably.

  2. Inequalities in Global Trade: A Cross-Country Comparison of Trade Network Position, Economic Wealth, Pollution and Mortality

    PubMed Central

    Prell, Christina; Sun, Laixiang; Feng, Kuishuang; Myroniuk, Tyler W.

    2015-01-01

    In this paper we investigate how structural patterns of international trade give rise to emissions inequalities across countries, and how such inequality in turn impact countries’ mortality rates. We employ Multi-regional Input-Output analysis to distinguish between sulfur-dioxide (SO2) emissions produced within a country’s boarders (production-based emissions) and emissions triggered by consumption in other countries (consumption-based emissions). We use social network analysis to capture countries’ level of integration within the global trade network. We then apply the Prais-Winsten panel estimation technique to a panel data set across 172 countries over 20 years (1990–2010) to estimate the relationships between countries’ level of integration and SO2 emissions, and the impact of trade integration and SO2 emission on mortality rates. Our findings suggest a positive, (log-) linear relationship between a country’s level of integration and both kinds of emissions. In addition, although more integrated countries are mainly responsible for both forms of emissions, our findings indicate that they also tend to experience lower mortality rates. Our approach offers a unique combination of social network analysis with multiregional input-output analysis, which better operationalizes intuitive concepts about global trade and trade structure. PMID:26642202

  3. Validation of the Atmospheric Infrared Sounder Water Vapor Retrievals Using Global Positioning System: Case Study in South Korea

    NASA Astrophysics Data System (ADS)

    Won, Jihye; Park, Kwan-Dong; Kim, Dusik; Ha, Jihyun

    2011-12-01

    The atmospheric infrared sounder (AIRS) sensor loaded on the Aqua satellite observes the global vertical structure of atmosphere and enables verification of the water vapor distribution over the entire area of South Korea. In this study, we performed a comparative analysis of the accuracy of the total precipitable water (TPW) provided as the AIRS level 2 standard retrieval product by Jet Propulsion Laboratory (JPL) over the South Korean area using the global positioning system (GPS) TPW data. The analysis TPW for the period of one year in 2008 showed that the accuracy of the data produced by the combination of the Advanced Microwave Sounding Unit sensor with the AIRS sensor to correct the effect of clouds (AIRS-X) was higher than that of the AIRS IR-only data (AIRS-I). The annual means of the root mean square error with reference to the GPS data were 5.2 kg/m2 and 4.3 kg/m2 for AIRS-I and AIRS-X, respectively. The accuracy of AIRS-X was higher in summer than in winter while measurement values of AIRS-I and AIRS-X were lower than those of GPS TPW to some extent.

  4. Inequalities in Global Trade: A Cross-Country Comparison of Trade Network Position, Economic Wealth, Pollution and Mortality.

    PubMed

    Prell, Christina; Sun, Laixiang; Feng, Kuishuang; Myroniuk, Tyler W

    2015-01-01

    In this paper we investigate how structural patterns of international trade give rise to emissions inequalities across countries, and how such inequality in turn impact countries' mortality rates. We employ Multi-regional Input-Output analysis to distinguish between sulfur-dioxide (SO2) emissions produced within a country's boarders (production-based emissions) and emissions triggered by consumption in other countries (consumption-based emissions). We use social network analysis to capture countries' level of integration within the global trade network. We then apply the Prais-Winsten panel estimation technique to a panel data set across 172 countries over 20 years (1990-2010) to estimate the relationships between countries' level of integration and SO2 emissions, and the impact of trade integration and SO2 emission on mortality rates. Our findings suggest a positive, (log-) linear relationship between a country's level of integration and both kinds of emissions. In addition, although more integrated countries are mainly responsible for both forms of emissions, our findings indicate that they also tend to experience lower mortality rates. Our approach offers a unique combination of social network analysis with multiregional input-output analysis, which better operationalizes intuitive concepts about global trade and trade structure.

  5. Regaining America's leading global position in the innovation of science and technology: Increasing engineering program enrollment in higher education

    NASA Astrophysics Data System (ADS)

    Burklo, Daniel A.

    While the United States has always been a global leader in the innovation of science and technology, this leading global position is in jeopardy. As other developing countries produce intellectual capital in the form of engineers at increasing rates, the country will continue to lose ground. Today the need for the country to produce engineers is greater than ever before. Recognizing this need, attempts have been made to increase entrance into engineering fields in higher education by providing STEM (science, technology, engineering, and mathematics) activities during K-12 education. While STEM initiatives create awareness and interest, this study investigates what actually motivates individuals to choose engineering programs in higher education. A quantitative study utilizing survey results from 202 first year engineering students in the state of Ohio illustrates what has motivated them to choose engineering as a major. The study examines who, when, and what motivated the students to choose engineering by examining the relationship of influential people and STEM initiatives participated in during their K-12 education to enrollment in engineering programs at colleges and universities in the state of Ohio. The study proved the general hypothesis that there are influential people in an individual's college choice, such as the parent, and there are time periods during K-12 education when individuals are more motivated, such as the high school years. The study also showed a positive correlation between the motivation toward engineering programs and the number of STEM opportunities in which individuals participated yet there was little difference when comparing the different types of STEM initiatives.

  6. Effects of Reliability and Global Context on Explicit and Implicit Measures of Sensed Hand Position in Cursor-Control Tasks

    PubMed Central

    Rand, Miya K.; Heuer, Herbert

    2016-01-01

    In a cursor-control task in which the motion of the cursor is rotated randomly relative to the movement of the hand, the sensed directions of hand and cursor are mutually biased. In our previous study, we used implicit and explicit measures of the bias of sensed hand direction toward the direction of the cursor and found different characteristics. The present study serves to explore further differences and commonalities of these measures. In Experiment 1, we examined the effects of different relative reliabilities of visual and proprioceptive information on the explicitly and implicitly assessed bias of sensed hand direction. In two conditions, participants made an aiming movement and returned to the start position immediately or after a delay of 6 s during which the cursor was no longer visible. The unimodal proprioceptive information on final hand position in the delayed condition served to increase its relative reliability. As a result, the bias of sensed hand direction toward the direction of the cursor was reduced for the explicit measure, with a complementary increase of the bias of sensed cursor direction, but unchanged for the implicit measure. In Experiment 2, we examined the influence of global context, specifically of the across-trial sequence of judgments of hand and cursor direction. Both explicitly and implicitly assessed biases of sensed hand direction did not significantly differ between the alternated condition (trial-to-trial alternations of judgments of hand and cursor direction) and the blocked condition (judgments of hand or cursor directions in all trials). They both substantially decreased from the alternated to the randomized condition (random sequence of judgments of hand and cursor direction), without a complementary increase of the bias of sensed cursor direction. We conclude that our explicit and implicit measures are equally sensitive to variations of coupling strength as induced by the variation of global context in Experiment 2, but

  7. Automatic and reproducible positioning of phase-contrast MRI for the quantification of global cerebral blood flow.

    PubMed

    Liu, Peiying; Lu, Hanzhang; Filbey, Francesca M; Pinkham, Amy E; McAdams, Carrie J; Adinoff, Bryon; Daliparthi, Vamsi; Cao, Yan

    2014-01-01

    Phase-Contrast MRI (PC-MRI) is a noninvasive technique to measure blood flow. In particular, global but highly quantitative cerebral blood flow (CBF) measurement using PC-MRI complements several other CBF mapping methods such as arterial spin labeling and dynamic susceptibility contrast MRI by providing a calibration factor. The ability to estimate blood supply in physiological units also lays a foundation for assessment of brain metabolic rate. However, a major obstacle before wider applications of this method is that the slice positioning of the scan, ideally placed perpendicular to the feeding arteries, requires considerable expertise and can present a burden to the operator. In the present work, we proposed that the majority of PC-MRI scans can be positioned using an automatic algorithm, leaving only a small fraction of arteries requiring manual positioning. We implemented and evaluated an algorithm for this purpose based on feature extraction of a survey angiogram, which is of minimal operator dependence. In a comparative test-retest study with 7 subjects, the blood flow measurement using this algorithm showed an inter-session coefficient of variation (CoV) of 4.07 ± 3.03%. The Bland-Altman method showed that the automatic method differs from the manual method by between -8% and 11%, for 95% of the CBF measurements. This is comparable to the variance in CBF measurement using manually-positioned PC MRI alone. In a further application of this algorithm to 157 consecutive subjects from typical clinical cohorts, the algorithm provided successful positioning in 89.7% of the arteries. In 79.6% of the subjects, all four arteries could be planned using the algorithm. Chi-square tests of independence showed that the success rate was not dependent on the age or gender, but the patients showed a trend of lower success rate (p = 0.14) compared to healthy controls. In conclusion, this automatic positioning algorithm could improve the application of PC-MRI in CBF

  8. Adaptive Correlation Space Adjusted Open-Loop Tracking Approach for Vehicle Positioning with Global Navigation Satellite System in Urban Areas.

    PubMed

    Ruan, Hang; Li, Jian; Zhang, Lei; Long, Teng

    2015-08-28

    For vehicle positioning with Global Navigation Satellite System (GNSS) in urban areas, open-loop tracking shows better performance because of its high sensitivity and superior robustness against multipath. However, no previous study has focused on the effects of the code search grid size on the code phase measurement accuracy of open-loop tracking. Traditional open-loop tracking methods are performed by the batch correlators with fixed correlation space. The code search grid size, which is the correlation space, is a constant empirical value and the code phase measuring accuracy will be largely degraded due to the improper grid size, especially when the signal carrier-to-noise density ratio (C/N₀) varies. In this study, the Adaptive Correlation Space Adjusted Open-Loop Tracking Approach (ACSA-OLTA) is proposed to improve the code phase measurement dependent pseudo range accuracy. In ACSA-OLTA, the correlation space is adjusted according to the signal C/N₀. The novel Equivalent Weighted Pseudo Range Error (EWPRE) is raised to obtain the optimal code search grid sizes for different C/N₀. The code phase measuring errors of different measurement calculation methods are analyzed for the first time. The measurement calculation strategy of ACSA-OLTA is derived from the analysis to further improve the accuracy but reduce the correlator consumption. Performance simulation and real tests confirm that the pseudo range and positioning accuracy of ASCA-OLTA are better than the traditional open-loop tracking methods in the usual scenarios of urban area.

  9. Comparative study of tracking performance in an airborne tracking radar simulator using global positioning system versus monopulse radar techniques

    NASA Astrophysics Data System (ADS)

    Nguyen, Joseph H.; Holley, William D.; Gagnon, Garry

    1993-10-01

    This paper attempts to address the tracking accuracy between the two systems under test. A monopulse radar model was developed to theoretically calculate the would-be measured angle and angle variances. Essentially, measurements of the target's angle, angle variances, range and range rate from the monopulse radar receiver of an aircraft are assessed against the tracking performance of an airborne simulator which uses the time, space, position information (TSPI) delivered from a global positioning system (GPS) system. The accuracy of measurements from a monopulse radar primarily depends on the signal-to-noise ratio (SNR), distance from target in this case, but information received from the GPS Space Vehicle would be virtually jamfree, and independent of distance. Tracking using GPS data however requires good data link between airborne participants. The simulation fidelity becomes an issue when the target is in close range track. The monopulse random slope error and target glint become significant, while the resolution from GPS data links remains the same.

  10. Fast Measurement and Reconstruction of Large Workpieces with Freeform Surfaces by Combining Local Scanning and Global Position Data

    PubMed Central

    Chen, Zhe; Zhang, Fumin; Qu, Xinghua; Liang, Baoqiu

    2015-01-01

    In this paper, we propose a new approach for the measurement and reconstruction of large workpieces with freeform surfaces. The system consists of a handheld laser scanning sensor and a position sensor. The laser scanning sensor is used to acquire the surface and geometry information, and the position sensor is utilized to unify the scanning sensors into a global coordinate system. The measurement process includes data collection, multi-sensor data fusion and surface reconstruction. With the multi-sensor data fusion, errors accumulated during the image alignment and registration process are minimized, and the measuring precision is significantly improved. After the dense accurate acquisition of the three-dimensional (3-D) coordinates, the surface is reconstructed using a commercial software piece, based on the Non-Uniform Rational B-Splines (NURBS) surface. The system has been evaluated, both qualitatively and quantitatively, using reference measurements provided by a commercial laser scanning sensor. The method has been applied for the reconstruction of a large gear rim and the accuracy is up to 0.0963 mm. The results prove that this new combined method is promising for measuring and reconstructing the large-scale objects with complex surface geometry. Compared with reported methods of large-scale shape measurement, it owns high freedom in motion, high precision and high measurement speed in a wide measurement range. PMID:26091396

  11. Lessons Learned from Two Years of On-Orbit Global Positioning System Experience on International Space Station

    NASA Technical Reports Server (NTRS)

    Gomez, Susan F.; Lammers, Michael L.

    2004-01-01

    The Global Positioning System Subsystem (GPS) for International Space Station (ISS) was activated April 12,2002 following the installation of the SO truss segment that included the GPS antennas on Shuttle mission STS-110. The ISS GPS receiver became the primary source for position, velocity, and attitude information for ISS two days after activation. The GPS receiver also provides a time reference for manual control of ISS time, and will be used for automatic time updates after problems are resolved with the output from the receiver. After two years of on-orbit experience, the GPS continues to be used as the primary navigation source for ISS; however, enough problems have surfaced that the firmware in the GPS attitude code has had to be totally rewritten and new algorithms developed, the firmware that processed the time output from the GPS receiver had to be rewritten, while the GPS navigation code has had minor revisions. The factors contributing to the delivery of a GPS receiver for use on ISS that requires extensive operator intervention to function are discussed. Observations from two years worth of GPS solutions will also be discussed. The technical solutions to the anomalous GPS receiver behavior will be discussed.

  12. Fast Measurement and Reconstruction of Large Workpieces with Freeform Surfaces by Combining Local Scanning and Global Position Data.

    PubMed

    Chen, Zhe; Zhang, Fumin; Qu, Xinghua; Liang, Baoqiu

    2015-01-01

    In this paper, we propose a new approach for the measurement and reconstruction of large workpieces with freeform surfaces. The system consists of a handheld laser scanning sensor and a position sensor. The laser scanning sensor is used to acquire the surface and geometry information, and the position sensor is utilized to unify the scanning sensors into a global coordinate system. The measurement process includes data collection, multi-sensor data fusion and surface reconstruction. With the multi-sensor data fusion, errors accumulated during the image alignment and registration process are minimized, and the measuring precision is significantly improved. After the dense accurate acquisition of the three-dimensional (3-D) coordinates, the surface is reconstructed using a commercial software piece, based on the Non-Uniform Rational B-Splines (NURBS) surface. The system has been evaluated, both qualitatively and quantitatively, using reference measurements provided by a commercial laser scanning sensor. The method has been applied for the reconstruction of a large gear rim and the accuracy is up to 0.0963 mm. The results prove that this new combined method is promising for measuring and reconstructing the large-scale objects with complex surface geometry. Compared with reported methods of large-scale shape measurement, it owns high freedom in motion, high precision and high measurement speed in a wide measurement range.

  13. Match play demands of 11 versus 11 professional football using Global Positioning System tracking: Variations across common playing formations.

    PubMed

    Tierney, Peter J; Young, Andrew; Clarke, Neil D; Duncan, Michael J

    2016-10-01

    This study aimed to examine Global Positioning System (GPS) determined movement patterns across the 5 most common playing formations (4-4-2; 4-3-3; 3-5-2; 3-4-3; 4-2-3-1) employed in 11 versus 11 football match play in England. Elite male footballers (n=46) were monitored over the course of a season; total distance (TD), high speed running (HSR), high metabolic load distance (HMLD), high speed accelerations (Acc) and decelerations (Dec) data was collected for analysis. It was found that 3-5-2 formation elicited higher TD (10528±565m, p=0.05), HSR (642±215m, p=0.001), and HMLD (2025±304m, p=0.001) than all other formations and above average Acc and Dec (34±7, p=0.036 and 57±10, p=0.006), with 4-2-3-1 eliciting the highest Acc and Dec (38±8 and 61±12). Positional data showed that CM in 4-3-3 covered >11% TD than in 4-4-2 (p=0.012). FW in 3-5-2 covered >45% HSR than in 4-2-3-1 (p=0.004). CM in 4-3-3 covered >14% HMLD than in 4-4-2 (p=0.367). FW in 4-3-3 performed >49% accelerations than in 4-2-3-1 (p=0.293). WD in 3-5-2 performed >20% more decelerations than in 4-4-2 (p=0.161). This study is important for coaches understanding, that positional physical characteristics are influenced by the demands of playing in different formations during match play. PMID:27269201

  14. Match play demands of 11 versus 11 professional football using Global Positioning System tracking: Variations across common playing formations.

    PubMed

    Tierney, Peter J; Young, Andrew; Clarke, Neil D; Duncan, Michael J

    2016-10-01

    This study aimed to examine Global Positioning System (GPS) determined movement patterns across the 5 most common playing formations (4-4-2; 4-3-3; 3-5-2; 3-4-3; 4-2-3-1) employed in 11 versus 11 football match play in England. Elite male footballers (n=46) were monitored over the course of a season; total distance (TD), high speed running (HSR), high metabolic load distance (HMLD), high speed accelerations (Acc) and decelerations (Dec) data was collected for analysis. It was found that 3-5-2 formation elicited higher TD (10528±565m, p=0.05), HSR (642±215m, p=0.001), and HMLD (2025±304m, p=0.001) than all other formations and above average Acc and Dec (34±7, p=0.036 and 57±10, p=0.006), with 4-2-3-1 eliciting the highest Acc and Dec (38±8 and 61±12). Positional data showed that CM in 4-3-3 covered >11% TD than in 4-4-2 (p=0.012). FW in 3-5-2 covered >45% HSR than in 4-2-3-1 (p=0.004). CM in 4-3-3 covered >14% HMLD than in 4-4-2 (p=0.367). FW in 4-3-3 performed >49% accelerations than in 4-2-3-1 (p=0.293). WD in 3-5-2 performed >20% more decelerations than in 4-4-2 (p=0.161). This study is important for coaches understanding, that positional physical characteristics are influenced by the demands of playing in different formations during match play.

  15. A new method for estimating the number of non-differentially expressed genes.

    PubMed

    Wu, J; Liu, C Y; Chen, W T; Ma, W Y; Ding, Y

    2016-01-01

    Control of the false discovery rate is a statistical method that is widely used when identifying differentially expressed genes in high-throughput sequencing assays. It is often calculated using an adaptive linear step-up procedure in which the number of non-differentially expressed genes should be estimated accurately. In this paper, we discuss the estimation of this parameter and point out defects in the original estimation method. We also propose a new estimation method and provide the error estimation. We compared the estimation results from the two methods in a simulation study that produced a mean, standard deviation, range, and root mean square error. The results revealed that there was little difference in the mean between the two methods, but the standard deviation, range, and root mean square error obtained using the new method were much smaller than those produced by the original method, which indicates that the new method is more accurate and robust. Furthermore, we used real microarray data to verify the conclusion. Finally we provide a suggestion when analyzing differentially expressed genes using statistical methods. PMID:27051004

  16. Detecting Splicing Variants in Idiopathic Pulmonary Fibrosis from Non-Differentially Expressed Genes

    PubMed Central

    Deng, Nan; Sanchez, Cecilia G.; Lasky, Joseph A.; Zhu, Dongxiao

    2013-01-01

    Idiopathic pulmonary fibrosis (IPF) is an interstitial lung disease of unknown cause that lacks a proven therapy for altering its high mortality rate. Microarrays have been employed to investigate the pathogenesis of IPF, but are presented mostly at the gene-expression level due to technologic limitations. In as much as, alternative RNA splicing isoforms are increasingly identified as potential regulators of human diseases, including IPF, we propose a new approach with the capacity to detect splicing variants using RNA-seq data. We conducted a joint analysis of differential expression and differential splicing on annotated human genes and isoforms, and identified 122 non-differentially expressed genes with a high degree of “switch” between major and minor isoforms. Three cases with variant mechanisms for alternative splicing were validated using qRT-PCR, among the group of genes in which expression was not significantly changed at the gene level. We also identified 35 novel transcripts that were unique to the fibrotic lungs using exon-exon junction evidence, and selected a representative for qRT-PCR validation. The results of our study are likely to provide new insight into the pathogenesis of pulmonary fibrosis and may eventuate in new treatment targets. PMID:23844188

  17. Improve wildlife species tracking—Implementing an enhanced global positioning system data management system for California condors

    USGS Publications Warehouse

    Waltermire, Robert G.; Emmerich, Christopher U.; Mendenhall, Laura C.; Bohrer, Gil; Weinzierl, Rolf P.; McGann, Andrew J.; Lineback, Pat K.; Kern, Tim J.; Douglas, David C.

    2016-01-01

    U.S. Fish and Wildlife Service (USFWS) staff in the Pacific Southwest Region and at the Hopper Mountain National Wildlife Refuge Complex requested technical assistance to improve their global positioning system (GPS) data acquisition, management, and archive in support of the California Condor Recovery Program. The USFWS deployed and maintained GPS units on individual Gymnogyps californianus (California condor) in support of long-term research and daily operational monitoring and management of California condors. The U.S. Geological Survey (USGS) obtained funding through the Science Support Program to provide coordination among project participants, provide GPS Global System for Mobile Communication (GSM) transmitters for testing, and compare GSM/GPS with existing Argos satellite GPS technology. The USFWS staff worked with private companies to design, develop, and fit condors with GSM/GPS transmitters. The Movebank organization, an online database of animal tracking data, coordinated with each of these companies to automatically stream their GPS data into Movebank servers and coordinated with USFWS to improve Movebank software for managing transmitter data, including proofing/error checking of incoming GPS data. The USGS arranged to pull raw GPS data from Movebank into the USGS California Condor Management and Analysis Portal (CCMAP) (https://my.usgs.gov/ccmap) for production and dissemination of a daily map of condor movements including various automated alerts. Further, the USGS developed an automatic archiving system for pulling raw and proofed Movebank data into USGS ScienceBase to comply with the Federal Information Security Management Act of 2002. This improved data management system requires minimal manual intervention resulting in more efficient data flow from GPS data capture to archive status. As a result of the project’s success, Pinnacles National Park and the Ventana Wildlife Society California condor programs became partners and adopted the same

  18. Improve wildlife species tracking—Implementing an enhanced global positioning system data management system for California condors

    USGS Publications Warehouse

    Waltermire, Robert G.; Emmerich, Christopher U.; Mendenhall, Laura C.; Bohrer, Gil; Weinzierl, Rolf P.; McGann, Andrew J.; Lineback, Pat K.; Kern, Tim J.; Douglas, David C.

    2016-05-03

    U.S. Fish and Wildlife Service (USFWS) staff in the Pacific Southwest Region and at the Hopper Mountain National Wildlife Refuge Complex requested technical assistance to improve their global positioning system (GPS) data acquisition, management, and archive in support of the California Condor Recovery Program. The USFWS deployed and maintained GPS units on individual Gymnogyps californianus (California condor) in support of long-term research and daily operational monitoring and management of California condors. The U.S. Geological Survey (USGS) obtained funding through the Science Support Program to provide coordination among project participants, provide GPS Global System for Mobile Communication (GSM) transmitters for testing, and compare GSM/GPS with existing Argos satellite GPS technology. The USFWS staff worked with private companies to design, develop, and fit condors with GSM/GPS transmitters. The Movebank organization, an online database of animal tracking data, coordinated with each of these companies to automatically stream their GPS data into Movebank servers and coordinated with USFWS to improve Movebank software for managing transmitter data, including proofing/error checking of incoming GPS data. The USGS arranged to pull raw GPS data from Movebank into the USGS California Condor Management and Analysis Portal (CCMAP) (https://my.usgs.gov/ccmap) for production and dissemination of a daily map of condor movements including various automated alerts. Further, the USGS developed an automatic archiving system for pulling raw and proofed Movebank data into USGS ScienceBase to comply with the Federal Information Security Management Act of 2002. This improved data management system requires minimal manual intervention resulting in more efficient data flow from GPS data capture to archive status. As a result of the project’s success, Pinnacles National Park and the Ventana Wildlife Society California condor programs became partners and adopted the same

  19. Thermal Band Atmospheric Correction Using Atmospheric Profiles Derived from Global Positioning System Radio Occultation and the Atmospheric Infrared Sounder

    NASA Technical Reports Server (NTRS)

    Pagnutti, Mary; Holekamp, Kara; Stewart, Randy; Vaughan, Ronald D.

    2006-01-01

    This Rapid Prototyping Capability study explores the potential to use atmospheric profiles derived from GPS (Global Positioning System) radio occultation measurements and by AIRS (Atmospheric Infrared Sounder) onboard the Aqua satellite to improve surface temperature retrieval from remotely sensed thermal imagery. This study demonstrates an example of a cross-cutting decision support technology whereby NASA data or models are shown to improve a wide number of observation systems or models. The ability to use one data source to improve others will be critical to the GEOSS (Global Earth Observation System of Systems) where a large number of potentially useful systems will require auxiliary datasets as input for decision support. Atmospheric correction of thermal imagery decouples TOA radiance and separates surface emission from atmospheric emission and absorption. Surface temperature can then be estimated from the surface emission with knowledge of its emissivity. Traditionally, radiosonde sounders or atmospheric models based on radiosonde sounders, such as the NOAA (National Oceanic & Atmospheric Administration) ARL (Air Resources Laboratory) READY (Real-time Environmental Application and Display sYstem), provide the atmospheric profiles required to perform atmospheric correction. Unfortunately, these types of data are too spatially sparse and too infrequently taken. The advent of high accuracy, global coverage, atmospheric data using GPS radio occultation and AIRS may provide a new avenue for filling data input gaps. In this study, AIRS and GPS radio occultation derived atmospheric profiles from the German Aerospace Center CHAMP (CHAllenging Minisatellite Payload), the Argentinean Commission on Space Activities SAC-C (Satellite de Aplicaciones Cientificas-C), and the pair of NASA GRACE (Gravity Recovery and Climate Experiment) satellites are used as input data in atmospheric radiative transport modeling based on the MODTRAN (MODerate resolution atmospheric

  20. Performances of Different Global Positioning System Devices for Time-Location Tracking in Air Pollution Epidemiological Studies

    PubMed Central

    Wu, Jun; Jiang, Chengsheng; Liu, Zhen; Houston, Douglas; Jaimes, Guillermo; McConnell, Rob

    2010-01-01

    Background: People’s time-location patterns are important in air pollution exposure assessment because pollution levels may vary considerably by location. A growing number of studies are using global positioning systems (GPS) to track people’s time-location patterns. Many portable GPS units that archive location are commercially available at a cost that makes their use feasible for epidemiological studies. Methods: We evaluated the performance of five portable GPS data loggers and two GPS cell phones by examining positional accuracy in typical locations (indoor, outdoor, in-vehicle) and factors that influence satellite reception (building material, building type), acquisition time (cold and warm start), battery life, and adequacy of memory for data storage. We examined stationary locations (eg, indoor, outdoor) and mobile environments (eg, walking, traveling by vehicle or bus) and compared GPS locations to highly-resolved US Geological Survey (USGS) and Digital Orthophoto Quarter Quadrangle (DOQQ) maps. Results: The battery life of our tested instruments ranged from <9 hours to 48 hours. The acquisition of location time after startup ranged from a few seconds to >20 minutes and varied significantly by building structure type and by cold or warm start. No GPS device was found to have consistently superior performance with regard to spatial accuracy and signal loss. At fixed outdoor locations, 65%–95% of GPS points fell within 20-m of the corresponding DOQQ locations for all the devices. At fixed indoor locations, 50%–80% of GPS points fell within 20-m of the corresponding DOQQ locations for all the devices except one. Most of the GPS devices performed well during commuting on a freeway, with >80% of points within 10-m of the DOQQ route, but the performance was significantly impacted by surrounding structures on surface streets in highly urbanized areas. Conclusions: All the tested GPS devices had limitations, but we identified several devices which showed

  1. The Global Positioning System constellation as a space weather monitor: Comparison of electron measurements with Van Allen Probes data

    NASA Astrophysics Data System (ADS)

    Morley, Steven K.; Sullivan, John P.; Henderson, Michael G.; Blake, J. Bernard; Baker, Daniel N.

    2016-02-01

    Energetic electron observations in Earth's radiation belts are typically sparse, and multipoint studies often rely on serendipitous conjunctions. This paper establishes the scientific utility of the Combined X-ray Dosimeter (CXD), currently flown on 19 satellites in the Global Positioning System (GPS) constellation, by cross-calibrating energetic electron measurements against data from the Van Allen Probes. By breaking our cross calibration into two parts—one that removes any spectral assumptions from the CXD flux calculation and one that compares the energy spectra—we first validate the modeled instrument response functions, then the calculated electron fluxes. Unlike previous forward modeling of energetic electron spectra, we use a combination of four distributions that together capture a wide range of observed spectral shapes. Our two-step approach allowed us to identify, and correct for, small systematic offsets between block IIR and IIF satellites. Using the Magnetic Electron Ion Spectrometer and Relativistic Electron-Proton Telescope on Van Allen Probes as a "gold standard," we demonstrate that the CXD instruments are well understood. A robust statistical analysis shows that CXD and Van Allen Probes fluxes are similar and the measured fluxes from CXD are typically within a factor of 2 of Van Allen Probes at energies ≲4 MeV. We present data from 17 CXD-equipped GPS satellites covering the 2015 "St. Patrick's Day" geomagnetic storm to illustrate the scientific applications of such a high data density satellite constellation and therefore demonstrate that the GPS constellation is positioned to enable new insights in inner magnetospheric physics and space weather forecasting.

  2. A new tool to monitor training and performance of sport horses using global positioning system (GPS) with integrated GSM capabilities.

    PubMed

    Hebenbrock, M; Düe, M; Holzhausen, H; Sass, A; Stadler, P; Ellendorff, F

    2005-07-01

    Global Positioning Systems (GPS) are considered suitable to monitor the position and velocity of horses during cross-country competition or in training. Furthermore, simultaneous recording of life data such as heart rate could be useful to assess the horse's condition during exercise. To test the suitability and reliability of a commercially available GPS system with integrated heart rate recording system and with built in GSM for data transmission, the Fidelak Equipilot Type EP-2003-15/G-2.11 (EP-15/G) was evaluated first for reliability of pulse recording from a pulse generator within the physiological range of horses; furthermore distance, velocity and heart rate recordings were carried out on a standard 1000 m field track with five repetitions. Agreement (% deviation from actually measured distance and from stopwatch-distance based velocity calculations) and variability (Coefficient of Variation for distance, velocity, heart rate) were calculated. From the results it was safe to assume that the heart rate sensor recorded horse heart rates at a high degree of accuracy. Overall distances and velocities are in high agreement with actually measured values. However, overall variability expressed in terms of relative variability (C.V.) is smaller for distance recording (C.V. 0.68%) when compared to velocity (C.V. 1.01%). The system tested is suitable and reliable for simultaneously recording of distance, velocity and heart rates for horses during cross country exercise. GPS-based monitoring of movement along with simultaneous recording of physiological data and the possibility to call upon data will not only be of benefit for training horses or for surveillance during competition, it may also be suitable for distant patient monitoring and in behavioural studies as well as in veterinary medicine in general.

  3. The Global Positioning System constellation as a space weather monitor. Comparison of electron measurements with Van Allen Probes data

    DOE PAGES

    Morley, Steven K.; Sullivan, John P.; Henderson, Michael G.; Blake, J. Bernard; Baker, Daniel N.

    2016-02-06

    Energetic electron observations in Earth's radiation belts are typically sparse, and multipoint studies often rely on serendipitous conjunctions. This paper establishes the scientific utility of the Combined X-ray Dosimeter (CXD), currently flown on 19 satellites in the Global Positioning System (GPS) constellation, by cross-calibrating energetic electron measurements against data from the Van Allen Probes. By breaking our cross calibration into two parts—one that removes any spectral assumptions from the CXD flux calculation and one that compares the energy spectra—we first validate the modeled instrument response functions, then the calculated electron fluxes. Unlike previous forward modeling of energetic electron spectra, wemore » use a combination of four distributions that together capture a wide range of observed spectral shapes. Moreover, our two-step approach allowed us to identify, and correct for, small systematic offsets between block IIR and IIF satellites. Using the Magnetic Electron Ion Spectrometer and Relativistic Electron-Proton Telescope on Van Allen Probes as a “gold standard,” here we demonstrate that the CXD instruments are well understood. A robust statistical analysis shows that CXD and Van Allen Probes fluxes are similar and the measured fluxes from CXD are typically within a factor of 2 of Van Allen Probes at energies inline image4 MeV. Our team present data from 17 CXD-equipped GPS satellites covering the 2015 “St. Patrick's Day” geomagnetic storm to illustrate the scientific applications of such a high data density satellite constellation and therefore demonstrate that the GPS constellation is positioned to enable new insights in inner magnetospheric physics and space weather forecasting.« less

  4. Adaptive Correlation Space Adjusted Open-Loop Tracking Approach for Vehicle Positioning with Global Navigation Satellite System in Urban Areas

    PubMed Central

    Ruan, Hang; Li, Jian; Zhang, Lei; Long, Teng

    2015-01-01

    For vehicle positioning with Global Navigation Satellite System (GNSS) in urban areas, open-loop tracking shows better performance because of its high sensitivity and superior robustness against multipath. However, no previous study has focused on the effects of the code search grid size on the code phase measurement accuracy of open-loop tracking. Traditional open-loop tracking methods are performed by the batch correlators with fixed correlation space. The code search grid size, which is the correlation space, is a constant empirical value and the code phase measuring accuracy will be largely degraded due to the improper grid size, especially when the signal carrier-to-noise density ratio (C/N0) varies. In this study, the Adaptive Correlation Space Adjusted Open-Loop Tracking Approach (ACSA-OLTA) is proposed to improve the code phase measurement dependent pseudo range accuracy. In ACSA-OLTA, the correlation space is adjusted according to the signal C/N0. The novel Equivalent Weighted Pseudo Range Error (EWPRE) is raised to obtain the optimal code search grid sizes for different C/N0. The code phase measuring errors of different measurement calculation methods are analyzed for the first time. The measurement calculation strategy of ACSA-OLTA is derived from the analysis to further improve the accuracy but reduce the correlator consumption. Performance simulation and real tests confirm that the pseudo range and positioning accuracy of ASCA-OLTA are better than the traditional open-loop tracking methods in the usual scenarios of urban area. PMID:26343683

  5. Comparison of bottom-track to global positioning system referenced discharges measured using an acoustic Doppler current profiler

    USGS Publications Warehouse

    Wagner, C.R.; Mueller, D.S.

    2011-01-01

    A negative bias in discharge measurements made with an acoustic Doppler current profiler (ADCP) can be caused by the movement of sediment on or near the streambed. The integration of a global positioning system (GPS) to track the movement of the ADCP can be used to avoid the systematic negative bias associated with a moving streambed. More than 500 discharge transects from 63 discharge measurements with GPS data were collected at sites throughout the US, Canada, and New Zealand with no moving bed to compare GPS and bottom-track-referenced discharges. Although the data indicated some statistical bias depending on site conditions and type of GPS data used, these biases were typically about 0.5% or less. An assessment of differential correction sources was limited by a lack of data collected in a range of different correction sources and different GPS receivers at the same sites. Despite this limitation, the data indicate that the use of Wide Area Augmentation System (WAAS) corrected positional data is acceptable for discharge measurements using GGA as the boat-velocity reference. The discharge data based on GPS-referenced boat velocities from the VTG data string, which does not require differential correction, were comparable to the discharges based on GPS-referenced boat velocities from the differentially-corrected GGA data string. Spatial variability of measure discharges referenced to GGA, VTG and bottom-tracking is higher near the channel banks. The spatial variability of VTG-referenced discharges is correlated with the spatial distribution of maximum Horizontal Dilution of Precision (HDOP) values and the spatial variability of GGA-referenced discharges is correlated with proximity to channel banks. ?? 2011 Published by Elsevier B.V.

  6. Application of the Global Positioning System to crustal deformation measurements. 3: Result from the southern California borderlands

    SciTech Connect

    Larson, K.M.

    1993-12-01

    Five years of measurements from the Global Positioning System (GPS) satellites collected between 1986 and 1991 are used to investigate deformation in the offshore regions of southern California. GPS provides the first practical technique to make precise geodetic measurements in the region. The geodetic network is situated along the California coastline from Vandenberg (120.6 deg W, 34.6 deg N) to San Diego, with additional sites on Santa Cruz, San Nicolas, Santa Catalina, Santa Rosa, and San Clemente Islands. The precision of horizontal interstation vectors is subcentimeter, and the interstation vector rate between Owens Valley Radio Observatory (OVRO) and Vandenberg agrees with the very long baseline interferometry derived rate to within one standard deviation. No significant motion is observed in th e western Santa Barbara Channel between Vandenberg and Santa Rosa Island, 0.5 +/- 1.6 mm/yr, where the quoted uncertainties are one standard deviation. Motions in the eastern Santa Barbara Channel are consistent with compressional deformation of 6 +/- 1 mm/yr at N16 +/- 3 deg E. This motion is in agreement with seismicity and an independent geodetic analysis for the period 1971-1987 (Larsen, 1991). San Clemente Island is moving relative to San Diego at the rate of 5.9 +/- 1.8/yr at a direction of N38 +/- 20 deg W. The motion between San Nicolas Island and San Clemente Island, 0.8 +/- 1.5 mm/yr, is insignificant.

  7. Global positioning system measurements of deformations associated with the 1987 Superstition Hills earthquake - Evidence for conjugate faulting

    NASA Technical Reports Server (NTRS)

    Larsen, Shawn; Reilinger, Robert; Neugebauer, Helen; Strange, William

    1992-01-01

    Large station displacements observed from Imperial Valley Global Positioning System (GPS) compaigns are attributed to the November 24, 1987 Superstition Hills earthquake sequence. Thirty sites from a 42 station GPS network established in 1986 were reoccupied during 1988 and/or 1990. Displacements at three sites within 3 kilometers of the surface rupture approach 0.5 m. Eight additional stations within 20 km of the seismic zone are displaced at least 10 cm. This is the first occurrence of a large earthquake (M(sub S) 6.6) within a preexisting GPS network. Best-fitting uniform slip models of rectangular dislocations in an elastic half-space indicate 130 + or - 8 cm right-lateral displacement along the northwest-trending Superstition Hills fault and 30 + or - 10 cm left-lateral displacement along the conjugate northeast-trending Elmore Ranch fault. The geodetic moments are 9.4 x 10 (exp 25) dyne-cm and 2.3 x 10 (exp 25) dyne-cm for the Superstition Hills and Elmore Ranch faults, respectively, consistent with teleseismic source parameters. The data also suggest the post seismic slip along the Superstition Hills fault is concentrated at shallow depths. Distributed slip solutions using Singular Value Decomposition indicate near uniform displacement along the Elmore Ranch fault and concentrated slip to the northwest and southeast along the Superstition Hills fault. A significant component of non-seismic displacement is observed across the Imperial Valley, which is attributed in part to interseismic plate-boundary deformation.

  8. The validity and reliability of 5-Hz global positioning system units to measure team sport movement demands.

    PubMed

    Johnston, Richard J; Watsford, Mark L; Pine, Matthew J; Spurrs, Robert W; Murphy, Aron J; Pruyn, Elizabeth C

    2012-03-01

    The purpose of this research was to investigate the validity and the reliability of 5-Hz MinimaxX global positioning system (GPS) units measuring athlete movement demands. A team sport simulation circuit (files collected from each unit = 12) and flying 50-m sprints (files collected from each unit = 34) were undertaken, during which the total distance covered; peak speed; player load; the distance covered; time spent and number of efforts performed walking, jogging, running, high-speed running, and sprinting were examined. Movement demands were also separately categorized into low-intensity activity, high-intensity running, and very high-intensity running. The results revealed that GPS was a valid and reliable measure of total distance covered (p > 0.05, percentage typical error of measurement [%TEM] < 5%) and peak speed (p > 0.05, %TEM 5-10%). Further, GPS was found to be a reliable measure of player load (%TEM 4.9%) and the distance covered, time spent, and number of efforts performed at certain velocity zones (%TEM <5% to >10%). The level of GPS error was found to increase along with the velocity of exercise. The findings demonstrated that GPS is capable of measuring movement demands performed at velocities <20 km·h(-1), whereas more caution is to be exercised when analyzing movement demands collected by using GPS velocities >20 km·h(-1).

  9. Estimating the prevalence of active Helicobacter pylori infection in a rural community with global positioning system technology-assisted sampling.

    PubMed

    Melius, E J; Davis, S I; Redd, J T; Lewin, M; Herlihy, R; Henderson, A; Sobel, J; Gold, B; Cheek, J E

    2013-03-01

    We investigated a possible outbreak of H. pylori in a rural Northern Plains community. In a cross-sectional survey, we randomly sampled 244 households from a geocoded emergency medical system database. We used a complex survey design and global positioning system units to locate houses and randomly selected one eligible household member to administer a questionnaire and a 13C-urea breath test for active H. pylori infection (n = 166). In weighted analyses, active H. pylori infection was detected in 55·0% of the sample. Factors associated with infection on multivariate analysis included using a public drinking-water supply [odds ratio (OR) 12·2, 95% confidence interval (CI) 2·9-50·7] and current cigarette smoking (OR 4·1, 95% CI 1·7-9·6). People who lived in houses with more rooms, a possible indicator of decreased crowding in the home, were less likely to have active H. pylori infections (OR 0·7, 95% CI 0·5-0·9 for each additional room).

  10. Comparisons of line-of-sight water vapor observations using the global positioning system and a pointing microwave radiometer.

    SciTech Connect

    Braun, J.; Rocken, C.; Liljegren, J. C.; Environmental Research; Univ. Corporation for Atmospheric Research

    2003-05-01

    Line-of-sight measurements of integrated water vapor from a global positioning system (GPS) receiver and a microwave radiometer are compared. These two instruments were collocated at the central facility of the Department of Energy's Atmospheric Radiation Measurement Program's Southern Great Plains region, near Lamont, Oklahoma. The comparison was made using 47 days of observations in May and June of 2000. Weather conditions during this time period were variable with total integrated water vapor ranging from less than 10 to more than 50 mm. To minimize errors in the microwave radiometer observations, observations were compared during conditions when the liquid water measured by the radiometer was less than 0.1 mm. The linear correlation of the observations between the two instruments is 0.99 with a root-mean-square difference of the GPS water vapor to a linear fit of the microwave radiometer of 1.3 mm. The results from these comparisons are used to evaluate the ability of networks of GPS receivers to measure instantaneous line-of-sight integrals of water vapor. A discussion and analysis is provided regarding the additional information of the water vapor field contained in these observations compared to time- and space-averaged zenith and gradient measurements.

  11. Forward Model Studies of Water Vapor Using Scanning Microwave Radiometers, Global Positioning System, and Radiosondes during the Cloudiness Intercomparison Experiment

    SciTech Connect

    Mattioli, Vinia; Westwater, Ed R.; Gutman, S.; Morris, Victor R.

    2005-05-01

    Brightness temperatures computed from five absorption models and radiosonde observations were analyzed by comparing them with measurements from three microwave radiometers at 23.8 and 31.4 GHz. Data were obtained during the Cloudiness Inter-Comparison experiment at the U.S. Department of Energy's Atmospheric Radiation Measurement Program's (ARM) site in North-Central Oklahoma in 2003. The radiometers were calibrated using two procedures, the so-called instantaneous ?tipcal? method and an automatic self-calibration algorithm. Measurements from the radiometers were in agreement, with less than a 0.4-K difference during clear skies, when the instantaneous method was applied. Brightness temperatures from the radiometer and the radiosonde showed an agreement of less than 0.55 K when the most recent absorption models were considered. Precipitable water vapor (PWV) computed from the radiometers were also compared to the PWV derived from a Global Positioning System station that operates at the ARM site. The instruments agree to within 0.1 cm in PWV retrieval.

  12. A comparison of mapped and measured total ionospheric electron content using global positioning system and beacon satellite observations

    NASA Technical Reports Server (NTRS)

    Lanyi, Gabor E.; Roth, Titus

    1988-01-01

    Total ionospheric electron contents (TEC) were measured by global positioning system (GPS) dual-frequency receivers developed by the Jet Propulsion Laboratory. The measurements included P-code (precise ranging code) and carrier phase data for six GPS satellites during multiple five-hour observing sessions. A set of these GPS TEC measurements were mapped from the GPS lines of sight to the line of sight of a Faraday beacon satellite by statistically fitting the TEC data to a simple model of the ionosphere. The mapped GPS TEC values were compared with the Faraday rotation measurements. Because GPS transmitter offsets are different for each satellite and because some GPS receiver offsets were uncalibrated, the sums of the satellite and receiver offsets were estimated simultaneously with the TEC in a least squares procedure. The accuracy of this estimation procedure is evaluated indicating that the error of the GPS-determined line of sight TEC can be at or below 1 x 10 to the 16th el/sq cm. Consequently, the current level of accuracy is comparable to the Faraday rotation technique; however, GPS provides superior sky coverage.

  13. CytR Is a Global Positive Regulator of Competence, Type VI Secretion, and Chitinases in Vibrio cholerae.

    PubMed

    Watve, Samit S; Thomas, Jacob; Hammer, Brian K

    2015-01-01

    The facultative pathogen Vibrio cholerae transitions between its human host and aquatic reservoirs where it colonizes chitinous surfaces. Growth on chitin induces expression of chitin utilization genes, genes involved in DNA uptake by natural transformation, and a type VI secretion system that allows contact-dependent killing of neighboring bacteria. We have previously shown that the transcription factor CytR, thought to primarily regulate the pyrimidine nucleoside scavenging response, is required for natural competence in V. cholerae. Through high-throughput RNA sequencing (RNA-seq), we show that CytR positively regulates the majority of competence genes, the three type VI secretion operons, and the four known or predicted chitinases. We used transcriptional reporters and phenotypic analysis to determine the individual contributions of quorum sensing, which is controlled by the transcription factors HapR and QstR; chitin utilization that is mediated by TfoX; and pyrimidine starvation that is orchestrated by CytR, toward each of these processes. We find that in V. cholerae, CytR is a global regulator of multiple behaviors affecting fitness and adaptability in the environment.

  14. Mapping Typha Domingensis in the Cienega de Santa Clara Using Satellite Images, Global Positioning System, and Spectrometry

    USGS Publications Warehouse

    Sanchez, Richard D.; Burnett, Earl E.; Croxen, Fred

    2000-01-01

    The Cienega de Santa Clara, Sonora, Mexico, a brackish wetland area created near the delta of the Colorado River from drainage effluent flowing from the United States since 1977, may undergo changes owing to the operation of the Yuma Desalting Plant in the United States. This has become the largest wetland in the delta region containing rare and endangered species, yet little is known about the environmental impact of these changes. The water quality of the marsh is of growing concern to the Bureau of Reclamation (BOR) which operates the Desalting Plant. Consequently, the BOR solicited the U.S. Geological Survey to investigate the limits and usefulness of satellite, global positioning system (GPS), and spectra data to map the Typha domingensis (cattail) of the Cienega de Santa Clara. Typha domingensis was selected by the BOR as the Cienega de Santa Clara indicator species to best predict the environmental effects of effl uent from the Yuma Desalting Plant. The successful base mapping of Typha domingensis will provide a viable tool for long-term monitoring and stress detection in the Cienega de Santa Clara.

  15. CytR Is a Global Positive Regulator of Competence, Type VI Secretion, and Chitinases in Vibrio cholerae

    PubMed Central

    Hammer, Brian K.

    2015-01-01

    The facultative pathogen Vibrio cholerae transitions between its human host and aquatic reservoirs where it colonizes chitinous surfaces. Growth on chitin induces expression of chitin utilization genes, genes involved in DNA uptake by natural transformation, and a type VI secretion system that allows contact-dependent killing of neighboring bacteria. We have previously shown that the transcription factor CytR, thought to primarily regulate the pyrimidine nucleoside scavenging response, is required for natural competence in V. cholerae. Through high-throughput RNA sequencing (RNA-seq), we show that CytR positively regulates the majority of competence genes, the three type VI secretion operons, and the four known or predicted chitinases. We used transcriptional reporters and phenotypic analysis to determine the individual contributions of quorum sensing, which is controlled by the transcription factors HapR and QstR; chitin utilization that is mediated by TfoX; and pyrimidine starvation that is orchestrated by CytR, toward each of these processes. We find that in V. cholerae, CytR is a global regulator of multiple behaviors affecting fitness and adaptability in the environment. PMID:26401962

  16. Results of using the global positioning system to maintain the time and frequency synchronization in the Deep Space Network

    NASA Technical Reports Server (NTRS)

    Clements, P. A.; Kirk, A.; Unglaub, R.

    1987-01-01

    There are two hydrogen maser clocks located at each signal processing center (SPC) in the DSN. Close coordination of the time and frequency of the SPC clocks is needed to navigate spacecraft to the outer planets. A recent example was the Voyager spacecraft's encounter with Uranus in January 1986. The clocks were adjusted with the goal of minimizing time and frequency offsets between the SPCs at encounter. How time and frequency at each SPC is estimated using data acquired from the Global Positioning System Timing Receivers operating on the NBS-BIH (National Bureau of Standards-Bureau International de l'Heure) tracking schedule is described. These data are combined with other available timing receiver data to calculate the time offset estimates. The adjustment of the clocks is described. It was determined that long range hydrogen maser drift is quite predictable and adjustable within limits. This enables one to minimize time and frequency differences between the three SPCs for many months by matching the drift rates of the three standards. Data acquisition and processing techniques using a Kalman filter to make estimates of time and frequency offsets between the clocks at the SPCs and UTC(NBS) (Coordinated Universal Time realized at NBS) are described.

  17. Road grade quantification based on global positioning system data obtained from real-world vehicle fuel use and emissions measurements

    NASA Astrophysics Data System (ADS)

    Yazdani Boroujeni, Behdad; Frey, H. Christopher

    2014-03-01

    Real-world vehicle fuel use and emission rates depend on engine load, which is quantified in terms of Vehicle Specific Power (VSP). VSP depends on vehicle speed, acceleration, and road grade. There is not a standard method for measuring road grade from a moving vehicle. A method for quantifying grade is evaluated based on statistical analysis of multiple runs using low cost consumer grade Global Positioning System (GPS) receivers with in-built Barometric Altimeter (GPS/BA). The average grade precision is ±0.71, ±0.46, and ±0.31 percentage points, for sample sizes of 9, 18, and 36 GPS/BA runs, respectively, among 2213 individual 0.08 km road segments. In addition, 4 sets of repeated measurements were performed on the same routes using a high cost, high accuracy Differential GPS (DGPS). Both sets of GPS-based grade estimates compared well with those derived from LIght Detection And Ranging (LIDAR) data. GPS/BA and DGPS grade estimates were similar, except for high magnitude grades of 8-10 percent for which DGPS estimates are more accurate. DGPS is more sensitive to loss of signal; thus, a hybrid approach for substituting GPS/BA data for missing DGPS data at specific locations along a route is demonstrated. The local and overall effects of road grade on fuel use and emission rates are investigated for an example light duty gasoline vehicle.

  18. Comprehensive Comparisons of Satellite Data, Signals, and Measurements between the BeiDou Navigation Satellite System and the Global Positioning System.

    PubMed

    Jan, Shau-Shiun; Tao, An-Lin

    2016-01-01

    The Chinese BeiDou navigation satellite system (BDS) aims to provide global positioning service by 2020. The combined use of BDS and Global Positioning System (GPS) is proposed to provide navigation service with more stringent requirements. Actual satellite data, signals and measurements were collected for more than one month to analyze the positioning service qualities from both BDS and GPS. In addition to the conversions of coordinate and timing system, five data quality analysis (DQA) methods, three signal quality analysis (SQA) methods, and four measurement quality analysis (MQA) methods are proposed in this paper to improve the integrated positioning performance of BDS and GPS. As shown in the experiment results, issues related to BDS and GPS are resolved by the above proposed quality analysis methods. Thus, the anomalies in satellite data, signals and measurements can be detected by following the suggested resolutions to enhance the positioning performance of the combined use of BDS and GPS in the Asia Pacific region. PMID:27187403

  19. Comprehensive Comparisons of Satellite Data, Signals, and Measurements between the BeiDou Navigation Satellite System and the Global Positioning System.

    PubMed

    Jan, Shau-Shiun; Tao, An-Lin

    2016-05-13

    The Chinese BeiDou navigation satellite system (BDS) aims to provide global positioning service by 2020. The combined use of BDS and Global Positioning System (GPS) is proposed to provide navigation service with more stringent requirements. Actual satellite data, signals and measurements were collected for more than one month to analyze the positioning service qualities from both BDS and GPS. In addition to the conversions of coordinate and timing system, five data quality analysis (DQA) methods, three signal quality analysis (SQA) methods, and four measurement quality analysis (MQA) methods are proposed in this paper to improve the integrated positioning performance of BDS and GPS. As shown in the experiment results, issues related to BDS and GPS are resolved by the above proposed quality analysis methods. Thus, the anomalies in satellite data, signals and measurements can be detected by following the suggested resolutions to enhance the positioning performance of the combined use of BDS and GPS in the Asia Pacific region.

  20. Comprehensive Comparisons of Satellite Data, Signals, and Measurements between the BeiDou Navigation Satellite System and the Global Positioning System †

    PubMed Central

    Jan, Shau-Shiun; Tao, An-Lin

    2016-01-01

    The Chinese BeiDou navigation satellite system (BDS) aims to provide global positioning service by 2020. The combined use of BDS and Global Positioning System (GPS) is proposed to provide navigation service with more stringent requirements. Actual satellite data, signals and measurements were collected for more than one month to analyze the positioning service qualities from both BDS and GPS. In addition to the conversions of coordinate and timing system, five data quality analysis (DQA) methods, three signal quality analysis (SQA) methods, and four measurement quality analysis (MQA) methods are proposed in this paper to improve the integrated positioning performance of BDS and GPS. As shown in the experiment results, issues related to BDS and GPS are resolved by the above proposed quality analysis methods. Thus, the anomalies in satellite data, signals and measurements can be detected by following the suggested resolutions to enhance the positioning performance of the combined use of BDS and GPS in the Asia Pacific region. PMID:27187403

  1. The use of global positional satellite location in dementia: a feasibility study for a randomised controlled trial

    PubMed Central

    2014-01-01

    Background Getting lost outside is stressful for people with dementia and their caregivers and a leading cause of long-term institutionalisation. Although Global Positional Satellite (GPS) location has been promoted to facilitate safe walking, reduce caregivers’ anxiety and enable people with dementia to remain at home, there is little high quality evidence about its acceptability, effectiveness or cost-effectiveness. This observational study explored the feasibility of recruiting and retaining participants, and the acceptability of outcome measures, to inform decisions about the feasibility of a randomised controlled trial (RCT). Methods People with dementia who had been provided with GPS devices by local social-care services and their caregivers were invited to participate in this study. We undertook interviews with people with dementia, caregivers and professionals to explore the perceived utility and challenges of GPS location, and assessed quality of life (QoL) and mental health. We piloted three methods of calculating resource use: caregiver diary; bi-monthly telephone questionnaires; and interrogation of health and social care records. We asked caregivers to estimate the time spent searching if participants became lost before and whilst using GPS. Results Twenty people were offered GPS locations services by social-care services during the 8-month recruitment period. Of these, 14 agreed to be referred to the research team, 12 of these participated and provided data. Eight people with dementia and 12 caregivers were interviewed. Most participants and professionals were very positive about using GPS. Only one person completed a diary. Resource use, anxiety and depression and QoL questionnaires were considered difficult and were therefore declined by some on follow-up. Social care records were time consuming to search and contained many omissions. Caregivers estimated that GPS reduced searching time although the accuracy of this was not objectively verified

  2. The physical environment and health-enhancing activity during the school commute: global positioning system, geographical information systems and accelerometry.

    PubMed

    McMinn, David; Oreskovic, Nicolas M; Aitkenhead, Matt J; Johnston, Derek W; Murtagh, Shemane; Rowe, David A

    2014-05-01

    Active school travel is in decline. An understanding of the potential determinants of health-enhancing physical activity during the school commute may help to inform interventions aimed at reversing these trends. The purpose of this study was to identify the physical environmental factors associated with health-enhancing physical activity during the school commute. Data were collected in 2009 on 166 children commuting home from school in Scotland. Data on location and physical activity were measured using global positioning systems (GPS) and accelerometers, and mapped using geographical information systems (GIS). Multi-level logistic regression models accounting for repeated observations within participants were used to test for associations between each land-use category (road/track/path, other man-made, greenspace, other natural) and moderate-to-vigorous physical activity (MVPA). Thirty-nine children provided 2,782 matched data points. Over one third (37.1%) of children's school commute time was spent in MVPA. Children commuted approximately equal amounts of time via natural and man-made land-uses (50.2% and 49.8% respectively). Commuting via road/track/path was associated with increased likelihood of MVPA (Exp(B)=1.23, P <0.05), but this association was not seen for commuting via other manmade land-uses. No association was noted between greenspace use and MVPA, but travelling via other natural land-uses was associated with lower odds of MVPA (Exp(B)=0.32, P <0.05). Children spend equal amounts of time commuting to school via man-made and natural land-uses, yet man-made transportation route infrastructure appears to provide greater opportunities for achieving health-enhancing physical activity levels.

  3. Global positioning system data analysis: velocity ranges and a new definition of sprinting for field sport athletes.

    PubMed

    Dwyer, Dan B; Gabbett, Tim J

    2012-03-01

    Global positioning system (GPS) technology has improved the speed, accuracy, and ease of time-motion analyses of field sport athletes. The large volume of numerical data generated by GPS technology is usually summarized by reporting the distance traveled and time spent in various locomotor categories (e.g., walking, jogging, and running). There are a variety of definitions used in the literature to represent these categories, which makes it nearly impossible to compare findings among studies. The purpose of this work was to propose standard definitions (velocity ranges) that were determined by an objective analysis of time-motion data. In addition, we discuss the limitations of the existing definition of a sprint and present a new definition of sprinting for field sport athletes. Twenty-five GPS data files collected from 5 different sports (men's and women's field hockey, men's and women's soccer, and Australian Rules Football) were analyzed to identify the average velocity distribution. A curve fitting process was then used to determine the optimal placement of 4 Gaussian curves representing the typical locomotor categories. Based on the findings of these analyses, we make recommendations about sport-specific velocity ranges to be used in future time-motion studies of field sport athletes. We also suggest that a sprint be defined as any movement that reaches or exceeds the sprint threshold velocity for at least 1 second and any movement with an acceleration that occurs within the highest 5% of accelerations found in the corresponding velocity range. From a practical perspective, these analyses provide conditioning coaches with information on the high-intensity sprinting demands of field sport athletes, while also providing a novel method of capturing maximal effort, short-duration sprints.

  4. A new analytical method for the classification of time-location data obtained from the global positioning system (GPS).

    PubMed

    Kim, Taehyun; Lee, Kiyoung; Yang, Wonho; Yu, Seung Do

    2012-08-01

    Although the global positioning system (GPS) has been suggested as an alternative way to determine time-location patterns, its use has been limited. The purpose of this study was to evaluate a new analytical method of classifying time-location data obtained by GPS. A field technician carried a GPS device while simulating various scripted activities and recorded all movements by the second in an activity diary. The GPS device recorded geological data once every 15 s. The daily monitoring was repeated 18 times. The time-location data obtained by the GPS were compared with the activity diary to determine selection criteria for the classification of the GPS data. The GPS data were classified into four microenvironments (residential indoors, other indoors, transit, and walking outdoors); the selection criteria used were used number of satellites (used-NSAT), speed, and distance from residence. The GPS data were classified as indoors when the used-NSAT was below 9. Data classified as indoors were further classified as residential indoors when the distance from the residence was less than 40 m; otherwise, they were classified as other indoors. Data classified as outdoors were further classified as being in transit when the speed exceeded 2.5 m s(-1); otherwise, they were classified as walking outdoors. The average simple percentage agreement between the time-location classifications and the activity diary was 84.3 ± 12.4%, and the kappa coefficient was 0.71. The average differences between the time diary and the GPS results were 1.6 ± 2.3 h for the time spent in residential indoors, 0.9 ± 1.7 h for the time spent in other indoors, 0.4 ± 0.4 h for the time spent in transit, and 0.8 ± 0.5 h for the time spent walking outdoors. This method can be used to determine time-activity patterns in exposure-science studies.

  5. Using Global Positioning System Travel Data to Assess Real-World Energy Use of Plug-In Hybrid Electric Vehicles

    SciTech Connect

    Gonder, J.; Markel, T.; Thornton, M.; Simpson, A.

    2007-01-01

    Plug-in hybrid electric vehicles (PHEVs) have received considerable recent attention for their potential to reduce petroleum consumption significantly and quickly in the transportation sector. Analysis to aid the design of such vehicles and predict their real-world performance and fuel displacement must consider the driving patterns the vehicles will typically encounter. This paper goes beyond consideration of standardized certification cycless by leveraging state-of-the-art travel survey techniques that use Global Positioning System (GPS) technology to obtain a large set of real-world drive cycles from the surveyed vehicle fleet. This study specifically extracts 24-h, second-by-second driving profiles from a set of 227 GPS-instrumented vehicles in the St. Louis, Missouri, metropolitan area. The performance of midsize conventional, hybrid electric, and PHEV models is then simulated over the 227 full-day driving profiles to assess fuel consumption and operating characteristics of these vehicle technologies over a set of real-world usage patterns. In comparison to standard cycles used for certification procedures, the travel survey duty cycles include significantly more aggressive acceleration and deceleration events across the velocity spectrum, which affect vehicle operation and efficiency. Even under these more aggressive operating conditions, PHEVs using a blended charge-depleting energy management strategy consume less than 50% of the petroleum used by similar conventional vehicles. Although true prediction of the widespread real-world use of these vehicles requires expansion of the vehicle sample size and a refined accounting for the possible interaction of several variables with the sampled driving profiles, this study demonstrates a cutting-edge use of available GPS travel survey data to analyze the (highly drive cycle-dependent) performance of advanced technology PHEVs. This demonstration highlights new opportunities for using innovative GPS travel survey

  6. On Fast Post-Processing of Global Positioning System Simulator Truth Data and Receiver Measurements and Solutions Data

    NASA Technical Reports Server (NTRS)

    Kizhner, Semion; Day, John H. (Technical Monitor)

    2000-01-01

    Post-Processing of data related to a Global Positioning System (GPS) simulation is an important activity in qualification of a GPS receiver for space flight. Because a GPS simulator is a critical resource it is desirable to move off the pertinent simulation data from the simulator as soon as a test is completed. The simulator data files are usually moved to a Personal Computer (PC), where the post-processing of the receiver logged measurements and solutions data and simulated data is performed. Typically post-processing is accomplished using PC-based commercial software languages and tools. Because of commercial software systems generality their general-purpose functions are notoriously slow and more than often are the bottleneck problem even for short duration experiments. For example, it may take 8 hours to post-process data from a 6-hour simulation. There is a need to do post-processing faster, especially in order to use the previous test results as feedback for a next simulation setup. This paper demonstrates that a fast software linear interpolation algorithm is applicable to a large class of engineering problems, like GPS simulation data post-processing, where computational time is a critical resource and is one of the most important considerations. An approach is developed that allows to speed-up post-processing by an order of magnitude. It is based on improving the post-processing bottleneck interpolation algorithm using apriori information that is specific to the GPS simulation application. The presented post-processing scheme was used in support of a few successful space flight missions carrying GPS receivers. A future approach to solving the post-processing performance problem using Field Programmable Gate Array (FPGA) technology is described.

  7. Positions and shapes of the Martian plasma boundaries revisited after Phobos 2 and Mars Global Surveyor observations

    NASA Astrophysics Data System (ADS)

    Trotignon, J. G.; Mazelle, C.; Bertucci, C.; Acuna, M.

    For the purpose of producing updated models of the locations and shapes of both the bow shock and the magnetic pile-up boundary MPB of Mars curve fitting techniques have been applied to the observations of these plasma boundaries by Phobos 2 and Mars Global Surveyor MGS The boundary locations used in this study have mainly been identified from the Phobos 2 plasma wave system and the MGS MAG ER experiment data a huge amount of 700 shock 127 for Phobos 2 and 573 for MGS and 901 MPB 41 for Phobos 2 and 860 for MGS locations have thus been produced for the first time The merging of the Phobos 2 and MGS data bases has confirmed that the bow shock models derived previously from separate mission observations are in a quite good agreement with the available observations Nevertheless the better accuracy obtained in this study has to be accounted for the larger data sets and the better solar zenith angle coverage because of the far downstream crossings of the Martian bow shock by Phobos 2 Despite the small number of crossings of the Martian magnetic pile-up boundary also known as the planetopause magnetopause ion-composition boundary protonopause ldots by Phobos 2 a quite satisfactory model of the position and shape of this boundary has been produced Nevertheless the poor dayside coverage of the Phobos 2 observations did not allow an accurate modelling of the upstream part of the MPB to be done Conversely the lack of MPB crossings by MGS far downstream x -4 R M of the planet was a handicap for a realistic model of the

  8. Comparison of global positioning system (GPS) tracking and parent-report diaries to characterize children's time-location patterns.

    PubMed

    Elgethun, Kai; Yost, Michael G; Fitzpatrick, Cole T E; Nyerges, Timothy L; Fenske, Richard A

    2007-03-01

    Respondent error, low resolution, and study participant burden are known limitations of diary timelines used in exposure studies such as the National Human Exposure Assessment Survey (NHEXAS). Recent advances in global positioning system (GPS) technology have produced tracking devices sufficiently portable, functional and affordable to utilize in exposure assessment science. In this study, a differentially corrected GPS (dGPS) tracking device was compared to the NHEXAS diary timeline. The study also explored how GPS can be used to evaluate and improve such diary timelines by determining which location categories and which respondents are least likely to record "correct" time-location responses. A total of 31 children ages 3-5 years old wore a dGPS device for all waking hours on a weekend day while their parents completed the NHEXAS diary timeline to document the child's time-location pattern. Parents misclassified child time-location approximately 48% of the time using the NHEXAS timeline in comparison to dGPS. Overall concordance between methods was marginal (kappa=0.33-0.35). The dGPS device found that on average, children spent 76% of the 24-h study period in the home. The diary underestimated time the child spent in the home by 17%, while overestimating time spent inside other locations, outside at home, outside in other locations, and time spent in transit. Diary data for time spent outside at home and time in transit had the lowest response concordance with dGPS. The diaries of stay-at-home mothers and mothers working unskilled labor jobs had lower concordance with dGPS than did those of the other participants. The ability of dGPS tracking to collect continuous rather than categorical (ordinal) data was also demonstrated. It is concluded that automated GPS tracking measurements can improve the quality and collection efficiency of time-location data in exposure assessment studies, albeit for small cohorts.

  9. Time-location analysis for exposure assessment studies of children using a novel global positioning system instrument.

    PubMed Central

    Elgethun, Kai; Fenske, Richard A; Yost, Michael G; Palcisko, Gary J

    2003-01-01

    Global positioning system (GPS) technology is used widely for business and leisure activities and offers promise for human time-location studies to evaluate potential exposure to environmental contaminants. In this article we describe the development of a novel GPS instrument suitable for tracking the movements of young children. Eleven children in the Seattle area (2-8 years old) wore custom-designed data-logging GPS units integrated into clothing. Location data were transferred into geographic information systems software for map overlay, visualization, and tabular analysis. Data were grouped into five location categories (in vehicle, inside house, inside school, inside business, and outside) to determine time spent and percentage reception in each location. Additional experiments focused on spatial resolution, reception efficiency in typical environments, and sources of signal interference. Significant signal interference occurred only inside concrete/steel-frame buildings and inside a power substation. The GPS instruments provided adequate spatial resolution (typically about 2-3 m outdoors and 4-5 m indoors) to locate subjects within distinct microenvironments and distinguish a variety of human activities. Reception experiments showed that location could be tracked outside, proximal to buildings, and inside some buildings. Specific location information could identify movement in a single room inside a home, on a playground, or along a fence line. The instrument, worn in a vest or in bib overalls, was accepted by children and parents. Durability of the wiring was improved early in the study to correct breakage problems. The use of GPS technology offers a new level of accuracy for direct quantification of time-location activity patterns in exposure assessment studies. PMID:12515689

  10. An Analysis of Mobility in Global Rankings: Making Institutional Strategic Plans and Positioning for Building World-Class Universities

    ERIC Educational Resources Information Center

    Hou, Angela Yung Chi; Morse, Robert; Chiang, Chung-Lin

    2012-01-01

    Since the start of the twenty-first century, university rankings have become internationalized. Global rankings have a variety of uses, levels of popularity and rationales and they are here to stay. An examination of the results of the current global ranking reveals that well-reputed world-class universities are amongst the top ranked ones. A…

  11. Investigation for improving Global Positioning System (GPS) orbits using a discrete sequential estimator and stochastic models of selected physical processes

    NASA Technical Reports Server (NTRS)

    Goad, Clyde C.; Chadwell, C. David

    1993-01-01

    GEODYNII is a conventional batch least-squares differential corrector computer program with deterministic models of the physical environment. Conventional algorithms were used to process differenced phase and pseudorange data to determine eight-day Global Positioning system (GPS) orbits with several meter accuracy. However, random physical processes drive the errors whose magnitudes prevent improving the GPS orbit accuracy. To improve the orbit accuracy, these random processes should be modeled stochastically. The conventional batch least-squares algorithm cannot accommodate stochastic models, only a stochastic estimation algorithm is suitable, such as a sequential filter/smoother. Also, GEODYNII cannot currently model the correlation among data values. Differenced pseudorange, and especially differenced phase, are precise data types that can be used to improve the GPS orbit precision. To overcome these limitations and improve the accuracy of GPS orbits computed using GEODYNII, we proposed to develop a sequential stochastic filter/smoother processor by using GEODYNII as a type of trajectory preprocessor. Our proposed processor is now completed. It contains a correlated double difference range processing capability, first order Gauss Markov models for the solar radiation pressure scale coefficient and y-bias acceleration, and a random walk model for the tropospheric refraction correction. The development approach was to interface the standard GEODYNII output files (measurement partials and variationals) with software modules containing the stochastic estimator, the stochastic models, and a double differenced phase range processing routine. Thus, no modifications to the original GEODYNII software were required. A schematic of the development is shown. The observational data are edited in the preprocessor and the data are passed to GEODYNII as one of its standard data types. A reference orbit is determined using GEODYNII as a batch least-squares processor and the

  12. A new analytical method for the classification of time-location data obtained from the global positioning system (GPS).

    PubMed

    Kim, Taehyun; Lee, Kiyoung; Yang, Wonho; Yu, Seung Do

    2012-08-01

    Although the global positioning system (GPS) has been suggested as an alternative way to determine time-location patterns, its use has been limited. The purpose of this study was to evaluate a new analytical method of classifying time-location data obtained by GPS. A field technician carried a GPS device while simulating various scripted activities and recorded all movements by the second in an activity diary. The GPS device recorded geological data once every 15 s. The daily monitoring was repeated 18 times. The time-location data obtained by the GPS were compared with the activity diary to determine selection criteria for the classification of the GPS data. The GPS data were classified into four microenvironments (residential indoors, other indoors, transit, and walking outdoors); the selection criteria used were used number of satellites (used-NSAT), speed, and distance from residence. The GPS data were classified as indoors when the used-NSAT was below 9. Data classified as indoors were further classified as residential indoors when the distance from the residence was less than 40 m; otherwise, they were classified as other indoors. Data classified as outdoors were further classified as being in transit when the speed exceeded 2.5 m s(-1); otherwise, they were classified as walking outdoors. The average simple percentage agreement between the time-location classifications and the activity diary was 84.3 ± 12.4%, and the kappa coefficient was 0.71. The average differences between the time diary and the GPS results were 1.6 ± 2.3 h for the time spent in residential indoors, 0.9 ± 1.7 h for the time spent in other indoors, 0.4 ± 0.4 h for the time spent in transit, and 0.8 ± 0.5 h for the time spent walking outdoors. This method can be used to determine time-activity patterns in exposure-science studies. PMID:22739933

  13. Crustal Deformation Across the Basin and Range Province, Western United States, Measured with the Global Positioning System, 1992-2002

    NASA Astrophysics Data System (ADS)

    Hammond, W. C.; Thatcher, W.

    2002-12-01

    The Basin and Range province of the western United States lies east of the Sierra Nevada mountains and accommodates roughly 25% of the motion between the North American and Pacific Plates in this region. It is experiencing both active extension and dextral shear, whose orientation is consistent with relative plate motion, suggesting that the province is an important part of the overall plate boundary system. We present results from recent measurement of Basin and Range crustal motion using the Global Positioning System (GPS). As of September 2002, ten years of deformation will have been observed with GPS measurements in 1992,1996, 1998 and 2002. The 800 km long east-to-west line of campaign-style geodetic benchmarks extends from east of the Wasatch fault zone in Utah to west of the Genoa fault zone and Lake Tahoe in California's Northern Sierra Nevada mountains, primarily along Interstate Highway 50. In all there are velocities at 91 GPS sites, nearly double the number previously presented (Thatcher et al. [1999]), all of which will be measured in September 2002. Incorporating this new data is expected to reduce the uncertainty in earlier measurements that show the motion of the Sierra Nevada block with respect to non-deforming North America to be accommodated by right lateral shear and extensional deformation in Nevada and Utah. Velocity variation of about 9 mm/yr is concentrated in the western one-third of the network, with a lesser amount (roughly 3 mm/yr) localized to the easternmost edge of the network, in the vicinity of the Wasatch fault zone. Recent densification of the GPS network across these two zones will also improve the spatial resolution of the deformation in these regions. The greatest rate of present-day deformation occurs near the ruptures of the Fairview Peak and Rainbow Mountain earthquakes in the Central Nevada Seismic Zone, extending west past the Genoa fault into the Sierra Nevada. This strain rate pattern is correlated with the concentration

  14. Seasonal movement of the Slumgullion landslide determined from global positioning system surveys and field instrumentation, July 1998-March 2002

    USGS Publications Warehouse

    Coe, J.A.; Ellis, W.L.; Godt, J.W.; Savage, W.Z.; Savage, J.E.; Michael, J.A.; Kibler, J.D.; Powers, P.S.; Lidke, D.J.; Debray, S.

    2003-01-01

    Measurements of landslide movement made by global positioning system surveys and extensometers over a 3.5-year period show that the Slumgullion landslide in the San Juan Mountains of southwest Colorado moved throughout the monitoring period, but that daily velocities varied on a seasonal basis. Landslide velocities peaked in the early spring and summer in response to snowmelt and summer thunderstorms, respectively. Velocities were slowest in mid-winter when air and soil temperatures were coldest and precipitation was generally low and/or in the form of snow with a low water content. We hypothesize that the seasonal variability in velocities is due to ground-water levels and corresponding pore pressures that decrease when surface water is unavailable or cannot infiltrate frozen landslide material, and increase when surface water from melting snow or rainfall infiltrates unfrozen landslide material. We also suggest that patches of bouldery debris and fractures (created by continuous movement of the landslide) are conduits through which surface water can infiltrate, regardless of the frozen or unfrozen state of the landslide matrix material. Therefore, the availability of surface water is more important than landslide temperature in controlling the rate of landslide movement. This hypothesis is supported by field instrumentation data that show (1) landslide velocities coinciding with precipitation amounts regardless of the depth of freezing of landslide material, (2) spring and annual landslide velocities that were greatest when the depth of freezing was also the greatest, and (3) a rapid (several weeks or less) velocity and pore pressure response to rainfall. The persistent, but seasonally variable movement of the landslide, fits the bathtub model for landslide movement described by Baum and Reid [Baum, R.L., Reid, M.E., 2000. Ground water isolation by low-permeability clays in landslide shear zones. In: Bromhead, E.N., Dixon, N., Ibsen, M.-L. (Eds.), Landslides in

  15. Existence and global attractivity of positive periodic solutions of periodic n-species Lotka-Volterra competition systems with several deviating arguments.

    PubMed

    Fan, M; Wang, K; Jiang, D

    1999-08-01

    In this paper, we study the existence and global attractivity of positive periodic solutions of periodic n-species Lotka-Volterra competition systems. By using the method of coincidence degree and Lyapunov functional, a set of easily verifiable sufficient conditions are derived for the existence of at least one strictly positive (componentwise) periodic solution of periodic n-species Lotka-Volterra competition systems with several deviating arguments and the existence of a unique globally asymptotically stable periodic solution with strictly positive components of periodic n-species Lotka-Volterra competition system with several delays. Some new results are obtained. As an application, we also examine some special cases of the system we considered, which have been studied extensively in the literature. Some known results are improved and generalized.

  16. Examination of the Locus of Positional Effects on Children's Production of Plural -"s": Considerations from Local and Global Speech Planning

    ERIC Educational Resources Information Center

    Theodore, Rachel M.; Demuth, Katherine; Shattuck-Hufnagel, Stefanie

    2015-01-01

    Purpose: Prosodic and articulatory factors influence children's production of inflectional morphemes. For example, plural -"s" is produced more reliably in utterance-final compared to utterance-medial position (i.e., the positional effect), which has been attributed to the increased planning time in utterance-final position. In previous…

  17. Choosing a survey sample when data on the population are limited: a method using Global Positioning Systems and aerial and satellite photographs

    PubMed Central

    2012-01-01

    Background Various methods have been proposed for sampling when data on the population are limited. However, these methods are often biased. We propose a new method to draw a population sample using Global Positioning Systems and aerial or satellite photographs. Results We randomly sampled Global Positioning System locations in designated areas. A circle was drawn around each location with radius representing 20 m. Buildings in the circle were identified from satellite photographs; one was randomly chosen. Interviewers selected one household from the building, and interviews were conducted with eligible household members. Conclusions Participants had known selection probabilities, allowing proper estimation of parameters of interest and their variances. The approach was made possible by recent technological developments and access to satellite photographs. PMID:22967277

  18. Development of a GPS-aided motion measurement, pointing, and stabilization system for a Synthetic Aperture Radar. [Global Positioning System (GPS)

    SciTech Connect

    Fellerhoff, J.R.; Kohler, S.M.

    1991-01-01

    An advanced Synthetic Aperture Radar Motion Compensation System has been developed by Sandia National Laboratories (SNL). The system includes a miniaturized high accuracy ring laser gyro inertial measurement unit, a three axis gimbal pointing and stabilization assembly, a differential Global Positioning System (GPS) navigation aiding system, and a pilot guidance system. The system provides several improvements over previous SNL motion compensation systems and is capable of antenna stabilization to less than 0.01 degrees RMS and absolute position measurement to less than 5.0 meters RMS. These accuracies have been demonstrated in recent flight testing aboard a DHC-6-300 Twin Otter'' aircraft.

  19. Bathymetric surveys of Morse and Geist Reservoirs in central Indiana made with acoustic Doppler current profiler and global positioning system technology, 1996

    USGS Publications Warehouse

    Wilson, J.T.; Morlock, S.E.; Baker, N.T.

    1997-01-01

    Acoustic Doppler current profiler, global positioning system, and geographic information system technology were used to map the bathymetry of Morse and Geist Reservoirs, two artificial lakes used for public water supply in central Indiana. The project was a pilot study to evaluate the use of the technologies for bathymetric surveys. Bathymetric surveys were last conducted in 1978 on Morse Reservoir and in 1980 on Geist Reservoir; those surveys were done with conventional methods using networks of fathometer transects. The 1996 bathymetric surveys produced updated estimates of reservoir volumes that will serve as base-line data for future estimates of storage capacity and sedimentation rates.An acoustic Doppler current profiler and global positioning system receiver were used to collect water-depth and position data from April 1996 through October 1996. All water-depth and position data were imported to a geographic information system to create a data base. The geographic information system then was used to generate water-depth contour maps and to compute the volumes for each reservoir.The computed volume of Morse Reservoir was 22,820 acre-feet (7.44 billion gallons), with a surface area of 1,484 acres. The computed volume of Geist Reservoir was 19,280 acre-feet (6.29 billion gallons), with a surface area of 1,848 acres. The computed 1996 reservoir volumes are less than the design volumes and indicate that sedimentation has occurred in both reservoirs. Cross sections were constructed from the computer-generated surfaces for 1996 and compared to the fathometer profiles from the 1978 and 1980 surveys; analysis of these cross sections also indicates that some sedimentation has occurred in both reservoirs.The acoustic Doppler current profiler, global positioning system, and geographic information system technologies described in this report produced bathymetric maps and volume estimates more efficiently and with comparable or greater resolution than conventional

  20. Citizen Journalism and Digital Voices: Instituting a Collaborative Process between Global Youth, Technology and Media for Positive Social Change

    ERIC Educational Resources Information Center

    Worley, Robin

    2011-01-01

    Millions of youths in developing countries are described by UNICEF as "invisible and excluded." They live at the margins of society, facing challenges to their daily existence, powerless to make positive changes. But the emergence of citizen journalism and digital storytelling may offer these youths a chance to share their voices and positively…

  1. Characteristics of atmospheric gravity waves observed using the MU (Middle and Upper atmosphere) radar and GPS (Global Positioning System) radio occultation

    PubMed Central

    TSUDA, Toshitaka

    2014-01-01

    The wind velocity and temperature profiles observed in the middle atmosphere (altitude: 10–100 km) show perturbations resulting from superposition of various atmospheric waves, including atmospheric gravity waves. Atmospheric gravity waves are known to play an important role in determining the general circulation in the middle atmosphere by dynamical stresses caused by gravity wave breaking. In this paper, we summarize the characteristics of atmospheric gravity waves observed using the middle and upper atmosphere (MU) radar in Japan, as well as novel satellite data obtained from global positioning system radio occultation (GPS RO) measurements. In particular, we focus on the behavior of gravity waves in the mesosphere (50–90 km), where considerable gravity wave attenuation occurs. We also report on the global distribution of gravity wave activity in the stratosphere (10–50 km), highlighting various excitation mechanisms such as orographic effects, convection in the tropics, meteorological disturbances, the subtropical jet and the polar night jet. PMID:24492645

  2. Characteristics of atmospheric gravity waves observed using the MU (Middle and Upper atmosphere) radar and GPS (Global Positioning System) radio occultation.

    PubMed

    Tsuda, Toshitaka

    2014-01-01

    The wind velocity and temperature profiles observed in the middle atmosphere (altitude: 10-100 km) show perturbations resulting from superposition of various atmospheric waves, including atmospheric gravity waves. Atmospheric gravity waves are known to play an important role in determining the general circulation in the middle atmosphere by dynamical stresses caused by gravity wave breaking. In this paper, we summarize the characteristics of atmospheric gravity waves observed using the middle and upper atmosphere (MU) radar in Japan, as well as novel satellite data obtained from global positioning system radio occultation (GPS RO) measurements. In particular, we focus on the behavior of gravity waves in the mesosphere (50-90 km), where considerable gravity wave attenuation occurs. We also report on the global distribution of gravity wave activity in the stratosphere (10-50 km), highlighting various excitation mechanisms such as orographic effects, convection in the tropics, meteorological disturbances, the subtropical jet and the polar night jet.

  3. Characteristics of atmospheric gravity waves observed using the MU (Middle and Upper atmosphere) radar and GPS (Global Positioning System) radio occultation.

    PubMed

    Tsuda, Toshitaka

    2014-01-01

    The wind velocity and temperature profiles observed in the middle atmosphere (altitude: 10-100 km) show perturbations resulting from superposition of various atmospheric waves, including atmospheric gravity waves. Atmospheric gravity waves are known to play an important role in determining the general circulation in the middle atmosphere by dynamical stresses caused by gravity wave breaking. In this paper, we summarize the characteristics of atmospheric gravity waves observed using the middle and upper atmosphere (MU) radar in Japan, as well as novel satellite data obtained from global positioning system radio occultation (GPS RO) measurements. In particular, we focus on the behavior of gravity waves in the mesosphere (50-90 km), where considerable gravity wave attenuation occurs. We also report on the global distribution of gravity wave activity in the stratosphere (10-50 km), highlighting various excitation mechanisms such as orographic effects, convection in the tropics, meteorological disturbances, the subtropical jet and the polar night jet. PMID:24492645

  4. Definition and classification of chronic kidney disease: a position statement from Kidney Disease: Improving Global Outcomes (KDIGO).

    PubMed

    Levey, Andrew S; Eckardt, Kai-Uwe; Tsukamoto, Yusuke; Levin, Adeera; Coresh, Josef; Rossert, Jerome; De Zeeuw, Dick; Hostetter, Thomas H; Lameire, Norbert; Eknoyan, Garabed

    2005-06-01

    Chronic kidney disease (CKD) is a worldwide public health problem, with adverse outcomes of kidney failure, cardiovascular disease (CVD), and premature death. A simple definition and classification of kidney disease is necessary for international development and implementation of clinical practice guidelines. Kidney Disease: Improving Global Outcomes (KDIGO) conducted a survey and sponsored a controversies conference to (1) provide a clear understanding to both the nephrology and nonnephrology communities of the evidence base for the definition and classification recommended by Kidney Disease Quality Outcome Initiative (K/DOQI), (2) develop global consensus for the adoption of a simple definition and classification system, and (3) identify a collaborative research agenda and plan that would improve the evidence base and facilitate implementation of the definition and classification of CKD. The K/DOQI definition and classification were accepted, with clarifications. CKD is defined as kidney damage or glomerular filtration rate (GFR) <60 mL/min/1.73 m(2) for 3 months or more, irrespective of cause. Kidney damage in many kidney diseases can be ascertained by the presence of albuminuria, defined as albumin-to-creatinine ratio >30 mg/g in two of three spot urine specimens. GFR can be estimated from calibrated serum creatinine and estimating equations, such as the Modification of Diet in Renal Disease (MDRD) Study equation or the Cockcroft-Gault formula. Kidney disease severity is classified into five stages according to the level of GFR. Kidney disease treatment by dialysis and transplantation should be noted. Simple, uniform classifications of CKD by cause and by risks for kidney disease progression and CVD should be developed. PMID:15882252

  5. What can global positioning systems tell us about the contribution of different types of urban greenspace to children’s physical activity?

    PubMed Central

    Lachowycz, Kate; Jones, Andrew P.; Page, Angie S.; Wheeler, Benedict W.; Cooper, Ashley R.

    2013-01-01

    Urban greenspace is hypothesised to be an important location for physical activity in children, but their actual use of the resource to be active is not well known. In this study, global positioning systems (GPS) and accelerometers were used to measure activity within green environments for 902 English children aged 11-12. We summarised activity intensities in different types of greenspace on weekday evenings, weekend days, and by season. Parks were used for as much as 30% of outdoors moderate-vigorous activity at weekends and use was consistent across seasons. The findings suggest the importance of certain types of greenspace to children’s physical activity. PMID:22365385

  6. Environmental charging of spacecraft-tests of thermal control materials for use on the global positioning system flight space vehicle. Part 2: Specimen 6 to 9

    NASA Technical Reports Server (NTRS)

    Stevens, N. J.; Berkopec, F. D.; Blech, R. A.

    1976-01-01

    The NASA/USAF program on the Environmental Charging of Spacecraft Surfaces consists, in part, of experimental efforts directed toward evaluating the response of materials to the environmental charged particle flux. Samples of thermal blankets of the type to be used on the Global Positioning System Flight Space Vehicles were tested to determine their response to electron flux. The primary result observed was that no discharges were obtained with the quartz-fiber-fabric-covered multilayer insulation specimen. The taped aluminized polyester grounding system used on all specimens did not appear to grossly deteriorate with time; however, the specimens require specific external pressure to maintain constant grounding system resistance.

  7. A study of the application of differential techniques to the global positioning system for a helicopter precision approach

    NASA Technical Reports Server (NTRS)

    Mccall, D. L.

    1984-01-01

    The results of a simulation study to define the functional characteristics of a airborne and ground reference GPS receiver for use in a Differential GPS system are doumented. The operations of a variety of receiver types (sequential-single channel, continuous multi-channel, etc.) are evaluated for a typical civil helicopter mission scenario. The math model of each receiver type incorporated representative system errors including intentional degradation. The results include the discussion of the receiver relative performance, the spatial correlative properties of individual range error sources, and the navigation algorithm used to smooth the position data.

  8. Regena (Rga), a Drosophila homolog of the global negative transcriptional regulator CDC36 (NOT2) from yeast, modifies gene expression and suppresses position effect variegation.

    PubMed

    Frolov, M V; Benevolenskaya, E V; Birchler, J A

    1998-01-01

    A mutation in Regena (Rga) was isolated in screens for modifiers of white eye color gene expression. The reduction in the level of the Rga product results in a complex modulation of white mRNA both positively and negatively, depending on the developmental stage. In addition to white, Rga also affects the expression of several other tested genes, with one of them, Vinculin, being regulated in a strong sex-specific manner. Rga was cloned by transposon tagging. Its predicted product lacks any recognized nucleic acid-binding motif but is homologous to a global negative transcriptional regulator, CDC36 (NOT2), from yeast. Rga also acts as a suppressor of position effect variegation, suggesting that a possible function of Rga could be mediation of an interaction between chromatin proteins and the transcriptional complex.

  9. Coseismic and postseismic deformation due to the South Napa earthquake inferred from modeling of Global Positioning System data

    NASA Astrophysics Data System (ADS)

    Murray, J. R.; Svarc, J. L.; Pollitz, F. F.; Floyd, M.; Funning, G.; Johanson, I. A.

    2014-12-01

    Tectonic ground deformation due to the 24 August 2014 M6 South Napa earthquake was recorded by continuous GPS (CGPS) sites of the Plate Boundary Observatory, Bay Area Regional Deformation, and USGS networks. Additionally, survey-mode GPS (SGPS) measurements were carried out following the event to densify the spatial coverage and record postseismic deformation. We compare earthquake offsets estimated using two sets of time series for the same sites, one with position estimates at five minute intervals and the other at one day intervals. On average the offset magnitudes from the five-minute positions are ~70% those estimated from the daily data, demonstrating that substantial postseismic deformation occurred immediately following the coseismic slip. Fitting the daily position time series for sites within ~35 km of the epicenter with a combination of coseismic offset and a logarithmic decay that begins immediately following the event indicates that cumulative displacement from 25 August 2014 to 24 September 2014 is on average ~70% of the estimated displacement on 24 August at these sites. While earthquakes on creeping faults of the San Andreas system have often generated postseismic displacement of similar magnitude to the coseismic, the mapped trace associated with this earthquake was not known to creep. Using the coseismic offsets estimated from the five-minute solutions and a Bayesian inference approach, the most likely planar fault that passes through the epicenter and intersects the Earth's surface is vertical and strikes 155o, in good agreement with seismic moment tensor estimates. The peak GPS-inferred coseismic slip extends ~12 km northwest and up-dip of the hypocenter. Initial postseismic slip models derived from GPS data show shallow afterslip near and to the southeast of the inferred coseismic slip; the afterslip is generally shallower and southeast of the zone of aftershocks. However, the resulting GPS residuals exhibit more complex spatial patterns that

  10. Stepwise positional-orientational order and the multicritical-multistructural global phase diagram of the s =3 /2 Ising model from renormalization-group theory

    NASA Astrophysics Data System (ADS)

    Yunus, ćaǧın; Renklioǧlu, Başak; Keskin, Mustafa; Berker, A. Nihat

    2016-06-01

    The spin-3/2 Ising model, with nearest-neighbor interactions only, is the prototypical system with two different ordering species, with concentrations regulated by a chemical potential. Its global phase diagram, obtained in d =3 by renormalization-group theory in the Migdal-Kadanoff approximation or equivalently as an exact solution of a d =3 hierarchical lattice, with flows subtended by 40 different fixed points, presents a very rich structure containing eight different ordered and disordered phases, with more than 14 different types of phase diagrams in temperature and chemical potential. It exhibits phases with orientational and/or positional order. It also exhibits quintuple phase transition reentrances. Universality of critical exponents is conserved across different renormalization-group flow basins via redundant fixed points. One of the phase diagrams contains a plastic crystal sequence, with positional and orientational ordering encountered consecutively as temperature is lowered. The global phase diagram also contains double critical points, first-order and critical lines between two ordered phases, critical end points, usual and unusual (inverted) bicritical points, tricritical points, multiple tetracritical points, and zero-temperature criticality and bicriticality. The four-state Potts permutation-symmetric subspace is contained in this model.

  11. Ctr9, a key subunit of PAFc, affects global estrogen signaling and drives ERα-positive breast tumorigenesis

    PubMed Central

    Zeng, Hao; Xu, Wei

    2015-01-01

    The human RNA polymerase II (RNAPII)-associated factor complex (hPAFc) and its individual subunits have been implicated in human diseases, including cancer. However, its involvement in breast cancer awaits investigation. Using data mining and human breast cancer tissue microarrays, we found that Ctr9, the key scaffold subunit in hPAFc, is highly expressed in estrogen receptor α-positive (ERα+) luminal breast cancer, and the high expression of Ctr9 correlates with poor prognosis. Knockdown of Ctr9 in ERα+ breast cancer cells almost completely erased estrogen-regulated transcriptional response. At the molecular level, Ctr9 enhances ERα protein stability, promotes recruitment of ERα and RNAPII, and stimulates transcription elongation and transcription-coupled histone modifications. Knockdown of Ctr9, but not other hPAFc subunits, alters the morphology, proliferative capacity, and tamoxifen sensitivity of ERα+ breast cancer cells. Together, our study reveals that Ctr9, a key subunit of hPAFc, is a central regulator of estrogen signaling that drives ERα+ breast tumorigenesis, rendering it a potential target for the treatment of ERα+ breast cancer. PMID:26494790

  12. Global Regulator IscR Positively Contributes to Antimonite Resistance and Oxidation in Comamonas testosteroni S44

    PubMed Central

    Liu, Hongliang; Zhuang, Weiping; Zhang, Shengzhe; Rensing, Christopher; Huang, Jun; Li, Jie; Wang, Gejiao

    2015-01-01

    Antimonial compounds can be found as a toxic contaminant in the environment. Knowledge on mechanisms of microbial Sb oxidation and its role in microbial tolerance are limited. Previously, we found that Comamonas testosteroni S44 was resistant to multiple heavy metals and was able to oxidize the toxic antimonite [Sb(III)] to the much less toxic antimonate [Sb(V)]. In this study, transposon mutagenesis was performed in C. testosteroni S44 to isolate genes responsible for Sb(III) resistance and oxidation. An insertion mutation into iscR, which regulates genes involved in the biosynthesis of Fe-S clusters, generated a strain called iscR-280. This mutant strain was complemented with a plasmid carrying iscR to generate strain iscR-280C. Compared to the wild type S44 and iscR-280C, strain iscR-280 showed lower resistance to Sb(III) and a lower Sb(III) oxidation rate. Strain iscR-280 also showed lower resistance to As(III), Cd(II), Cu(II), and H2O2. In addition, intracellular γ-glutamylcysteine ligase (γ-GCL) activity and glutathione (GSH) content were decreased in the mutated strain iscR-280. Real-time RT-PCR and lacZ fusion expression assay indicated that transcription of iscR and iscS was induced by Sb(III). Results of electrophoretic mobility shift assay (EMSA) and bacterial one-hybrid (B1H) system demonstrated a positive interaction between IscR and its promoter region. The diverse defective phenotypes and various expression patterns suggest a role for IscR in contributing to multi-metal(loid)s resistance and Sb(III) oxidation via Fe-S cluster biogenesis and oxidative stress protection. Bacterial Sb(III) oxidation is a detoxification reaction. PMID:26734615

  13. Analysis of California Condor (Gymnogyps californianus) use of six management units using location data from global positioning system transmitters, southern California, 2004-09-Initial report

    USGS Publications Warehouse

    Johnson, Matthew; Kern, Jeffrey; Haig, Susan M.

    2010-01-01

    This report provides an analysis of California Condor (Gymnogyps californianus) space use of six management units in southern California (Hopper Mountain and Bitter Creek National Wildlife Refuges, Wildlands Conservancy-Wind Wolves Preserve, Tejon Mountain Village Specific Plan, California Condor Study Area, and the Tejon Ranch excluding Tejon Mountain Village Specific Plan and California Condor Study Area). Space use was analyzed to address urgent management needs using location data from Global Positioning System transmitters. The U.S. Fish and Wildlife Service provided the U.S. Geological Survey with location data (2004-09) for California Condors from Global Positioning System transmitters and Geographic Information System data for the six management units in southern California. We calculated relative concentration of use estimates for each management unit for each California Condor (n = 21) on an annual basis (n = 39 annual home ranges) and evaluated resource selection for the population each year using the individual as our sampling unit. The most striking result from our analysis was the recolonization of the Tejon Mountain Village Specific Plan, California Condor Study Area, and Tejon Ranch management units during 2008. During 2004-07, the home range estimate for two (25 percent) California Condors overlapped the Tejon Mountain Village Specific Plan, California Condor Study Area, and Tejon Ranch management units (n = 8), and use within the annual home range generally was bimodal and was concentrated on the Bitter Creek and Hopper Mountain National Wildlife Refuges. However, 10 (77 percent) California Condor home ranges overlapped the Tejon Mountain Village Specific Plan, California Condor Study Area, and Tejon Ranch management units during 2008 (n = 13), and by 2009, the home range of every condor carrying a Global Positioning System transmitter (n = 14) overlapped these management units. Space use was multimodal within the home range during 2008-09 and was

  14. Comment on 'Match Analysis of U9 and U10 English Premier League Academy Soccer Players using a Global Positioning System: Relevance for Talent Identification and Development'

    PubMed

    Carling, Christopher; Collins, Dave

    2014-08-21

    We read with interest the recent article written by Goto, Morris & Nevill: 'Match Analysis of U9 and U10 English Premier League Academy Soccer Players using a Global Positioning System: Relevance for Talent Identification and Development'. In summary, the authors reported time motion analysis data from match-play showing that players who were retained by their Academy covered a significantly greater distance overall and in low-speed running in comparison to peers who were released. Consequently, the authors discussed their results in the context of talent identification and development processes. In light of their findings and discussion, it is of our opinion that further debate in the context of the current body of literature is necessary.

  15. An approach to regional wetland digital elevation model development using a differential global positioning system and a custom-built helicopter-based surveying system

    USGS Publications Warehouse

    Jones, J.W.; Desmond, G.B.; Henkle, C.; Glover, R.

    2012-01-01

    Accurate topographic data are critical to restoration science and planning for the Everglades region of South Florida, USA. They are needed to monitor and simulate water level, water depth and hydroperiod and are used in scientific research on hydrologic and biologic processes. Because large wetland environments and data acquisition challenge conventional ground-based and remotely sensed data collection methods, the United States Geological Survey (USGS) adapted a classical data collection instrument to global positioning system (GPS) and geographic information system (GIS) technologies. Data acquired with this instrument were processed using geostatistics to yield sub-water level elevation values with centimetre accuracy (??15 cm). The developed database framework, modelling philosophy and metadata protocol allow for continued, collaborative model revision and expansion, given additional elevation or other ancillary data. ?? 2012 Taylor & Francis.

  16. Environmental charging of spacecraft surfaces: Tests of thermal control materials for use on the global positioning system flight space vehicle. Part 1: Specimens 1 to 5

    NASA Technical Reports Server (NTRS)

    Stevens, N. J.; Klinect, V. W.; Berkopec, F. D.

    1976-01-01

    The NASA/USAF program on Environmental Charging of Spacecraft Surfaces consists of experimental efforts directed toward evaluating the response of materials to the environmental charged particle flux. Samples of thermal blankets and second surface mirrors of the type to be used on the Global Positioning System Flight Space Vehicle were tested to determine their response to electron flux. The primary result observed was that the ground connection of the metal layers of the blanket, as made by the baseline grounding technique using serrated washers and grommets, deteriorated with time at test. The discharges observed on the blankets were the glow type, not the 'lightning' strike observed on past specimens. Testing was performed at ambient laboratory temperatures.

  17. Adjuvant Surgical Oophorectomy Plus Tamoxifen in Premenopausal Women With Operable Hormone Receptor-Positive Breast Cancer: A Global Treatment Option.

    PubMed

    Love, Richard R

    2016-08-01

    One third of annual new cases of breast cancer globally are now hormone receptor-positive tumors in premenopausal women from low- and middle-income countries. For this subgroup of women with breast cancer, high-income country guidelines suggest impractical and unaffordable adjuvant treatments. The balance of clinical trial evidence now suggests that surgical oophorectomy plus tamoxifen is a safe and practical treatment for these women in low- and middle-income countries. Additionally, new randomized trial data suggest that women in the second half of an anovulatory cycle benefit minimally from surgical oophorectomy done at this time, which implies that regularly cycling women will benefit more than has been shown from this procedure. Allred scoring of levels of hormone receptors is a practical and inexpensive approach to the assessment of magnitudes of response to oophorectomy plus tamoxifen. These circumstances suggest that more detailed consideration of this option should characterize clinical practice guidelines in high-income countries because of their global impact.

  18. The open service signal in space navigation data comparison of the Global Positioning System and the BeiDou Navigation Satellite System.

    PubMed

    Jan, Shau-Shiun; Tao, An-Lin

    2014-08-19

    More and more Global Navigation Satellite Systems (GNSSs) have been developed and are in operation. Before integrating information on various GNSSs, the differences between the various systems must be studied first. This research focuses on analyzing the navigation data differences between the Chinese BeiDou Navigation Satellite System (BDS) and the United States' Global Positioning System (GPS). In addition to explaining the impact caused by these two different coordinate and time systems, this research uses an actual open service signal in space (SIS) for both GPS and BDS to analyze their current system performance. Five data quality analysis (DQA) mechanisms are proposed in this research to validate both systems' SIS navigation data. These five DQAs evaluate the differences in ephemeris and almanac messages from both systems for stability and accuracy. After all of the DQAs, the different issues related to GPS and BDS satellite information are presented. Finally, based on these DQA results, this research provides suggested resolutions for the combined use of GPS and BDS for navigation and guidance.

  19. The Open Service Signal in Space Navigation Data Comparison of the Global Positioning System and the BeiDou Navigation Satellite System

    PubMed Central

    Jan, Shau-Shiun; Tao, An-Lin

    2014-01-01

    More and more Global Navigation Satellite Systems (GNSSs) have been developed and are in operation. Before integrating information on various GNSSs, the differences between the various systems must be studied first. This research focuses on analyzing the navigation data differences between the Chinese BeiDou Navigation Satellite System (BDS) and the United States' Global Positioning System (GPS). In addition to explaining the impact caused by these two different coordinate and time systems, this research uses an actual open service signal in space (SIS) for both GPS and BDS to analyze their current system performance. Five data quality analysis (DQA) mechanisms are proposed in this research to validate both systems' SIS navigation data. These five DQAs evaluate the differences in ephemeris and almanac messages from both systems for stability and accuracy. After all of the DQAs, the different issues related to GPS and BDS satellite information are presented. Finally, based on these DQA results, this research provides suggested resolutions for the combined use of GPS and BDS for navigation and guidance. PMID:25195848

  20. Natural and built environmental exposures on children's active school travel: A Dutch global positioning system-based cross-sectional study.

    PubMed

    Helbich, Marco; Emmichoven, Maarten J Zeylmans van; Dijst, Martin J; Kwan, Mei-Po; Pierik, Frank H; Vries, Sanne I de

    2016-05-01

    Physical inactivity among children is on the rise. Active transport to school (ATS), namely walking and cycling there, adds to children's activity level. Little is known about how exposures along actual routes influence children's transport behavior. This study examined how natural and built environments influence mode choice among Dutch children aged 6-11 years. 623 school trips were tracked with global positioning system. Natural and built environmental exposures were determined by means of a geographic information system and their associations with children's active/passive mode choice were analyzed using mixed models. The actual commuted distance is inversely associated with ATS when only personal, traffic safety, and weather features are considered. When the model is adjusted for urban environments, the results are reversed and distance is no longer significant, whereas well-connected streets and cycling lanes are positively associated with ATS. Neither green space nor weather is significant. As distance is not apparent as a constraining travel determinant when moving through urban landscapes, planning authorities should support children's ATS by providing well-designed cities.

  1. Natural and built environmental exposures on children's active school travel: A Dutch global positioning system-based cross-sectional study.

    PubMed

    Helbich, Marco; Emmichoven, Maarten J Zeylmans van; Dijst, Martin J; Kwan, Mei-Po; Pierik, Frank H; Vries, Sanne I de

    2016-05-01

    Physical inactivity among children is on the rise. Active transport to school (ATS), namely walking and cycling there, adds to children's activity level. Little is known about how exposures along actual routes influence children's transport behavior. This study examined how natural and built environments influence mode choice among Dutch children aged 6-11 years. 623 school trips were tracked with global positioning system. Natural and built environmental exposures were determined by means of a geographic information system and their associations with children's active/passive mode choice were analyzed using mixed models. The actual commuted distance is inversely associated with ATS when only personal, traffic safety, and weather features are considered. When the model is adjusted for urban environments, the results are reversed and distance is no longer significant, whereas well-connected streets and cycling lanes are positively associated with ATS. Neither green space nor weather is significant. As distance is not apparent as a constraining travel determinant when moving through urban landscapes, planning authorities should support children's ATS by providing well-designed cities. PMID:27010106

  2. Computer Programs to Display and Modify Data in Geographic Coordinates and Methods to Transfer Positions to and from Maps, with Applications to Gravity Data Processing, Global Positioning Systems, and 30-Meter Digital Elevation Models

    USGS Publications Warehouse

    Plouff, Donald

    1998-01-01

    Computer programs were written in the Fortran language to process and display gravity data with locations expressed in geographic coordinates. The programs and associated processes have been tested for gravity data in an area of about 125,000 square kilometers in northwest Nevada, southeast Oregon, and northeast California. This report discusses the geographic aspects of data processing. Utilization of the programs begins with application of a template (printed in PostScript format) to transfer locations obtained with Global Positioning Systems to and from field maps and includes a 5-digit geographic-based map naming convention for field maps. Computer programs, with source codes that can be copied, are used to display data values (printed in PostScript format) and data coverage, insert data into files, extract data from files, shift locations, test for redundancy, and organize data by map quadrangles. It is suggested that 30-meter Digital Elevation Models needed for gravity terrain corrections and other applications should be accessed in a file search by using the USGS 7.5-minute map name as a file name, for example, file '40117_B8.DEM' contains elevation data for the map with a southeast corner at lat 40? 07' 30' N. and lon 117? 52' 30' W.

  3. Patterns of intestinal schistosomiasis among mothers and young children from Lake Albert, Uganda: water contact and social networks inferred from wearable global positioning system dataloggers.

    PubMed

    Seto, Edmund Y W; Sousa-Figueiredo, José C; Betson, Martha; Byalero, Chris; Kabatereine, Narcis B; Stothard, J Russell

    2012-11-01

    The establishment of a national control programme (NCP) in Uganda has led to routine treatment of intestinal schistosomiasis with praziquantel in the communities along Lake Albert. However, because regular water contact remains a way of life for these populations, re-infection continues to mitigate the sustainability of the chemotherapy-based programme. A six-month longitudinal study was conducted in one Lake Albert community with the aim of characterizing water contact exposure and infection among mothers and their young preschool-aged children as the latter are not yet formally included within the NCP. At baseline the cohort of 37 mothers, 36 preschool-aged children had infection prevalences of 62% and 67%, respectively, which diminished to 20% and 29%, respectively, at the 6-month post-treatment follow-up. The subjects wore global positioning system (GPS) datalogging devices over a 3-day period shortly after baseline, allowing for the estimation of time spent at the lakeshore as an exposure metric, which was found to be associated with prevalence at follow-up (OR = 2.1, P = 0.01 for both mothers and young children and odds ratio (OR) = 4.4, P = 0.01 for young children alone). A social network of interpersonal interactions was also derived from the GPS data, and the exposures were positively associated both with the number and duration of peer interaction, suggesting the importance of socio-cultural factors associated with water contact behaviour. The findings illustrate reduction in both prevalence and intensity of infection in this community after treatment as well as remarkably high rates of water contact exposure and re-infection, particularly among younger children. We believe that this should now be formally considered within NCP, which may benefit from more in-depth ethnographic exploration of factors related to water contact as this should provide new opportunities for sustaining control.

  4. Application of a combined global positioning and heart rate monitoring system in jumper horses during an official competition - A preliminary study.

    PubMed

    Bazzano, Marilena; Giudice, Elisabetta; Rizzo, Maria; Congiu, Fulvio; Zumbo, Alessandro; Arfuso, Francesca; Di Pietro, Simona; Bruschetta, Daniele; Piccione, Giuseppe

    2016-06-01

    The aim of this study was to investigate whether a combined global positioning system (GPS)/heart rate (HR) monitoring system is a valuable tool to assess, step by step, the physiological response of HR and its relationship with speed in healthy horses competing in an official show jumping class. Six mares performing a standardised warm-up and jumping course were monitored using a HR/GPS device. Venous blood lactate (BL), assessed before and after exercise, showed a significant increase (P = 0.0004) following the physical effort. One-way analysis of variance (ANOVA) showed significant changes in HR throughout the experimental period. The analysis of HR data recorded during the warm-up jumping stage showed significantly higher HR (P = 0.001) in the recovery period compared to the related jumping phase. Shifting the fence height from 100 cm to 125 cm during the warm-up jumps was also found to cause a significant increase (P = 0.016) in HR. According to these preliminary results, the simultaneous logging of heart rate and speed has the potential to be a reliable and powerful technique for field testing that can help in the monitoring of the horse's response to jumping effort during training and competition. PMID:27342090

  5. Application of a combined global positioning and heart rate monitoring system in jumper horses during an official competition - A preliminary study.

    PubMed

    Bazzano, Marilena; Giudice, Elisabetta; Rizzo, Maria; Congiu, Fulvio; Zumbo, Alessandro; Arfuso, Francesca; Di Pietro, Simona; Bruschetta, Daniele; Piccione, Giuseppe

    2016-06-01

    The aim of this study was to investigate whether a combined global positioning system (GPS)/heart rate (HR) monitoring system is a valuable tool to assess, step by step, the physiological response of HR and its relationship with speed in healthy horses competing in an official show jumping class. Six mares performing a standardised warm-up and jumping course were monitored using a HR/GPS device. Venous blood lactate (BL), assessed before and after exercise, showed a significant increase (P = 0.0004) following the physical effort. One-way analysis of variance (ANOVA) showed significant changes in HR throughout the experimental period. The analysis of HR data recorded during the warm-up jumping stage showed significantly higher HR (P = 0.001) in the recovery period compared to the related jumping phase. Shifting the fence height from 100 cm to 125 cm during the warm-up jumps was also found to cause a significant increase (P = 0.016) in HR. According to these preliminary results, the simultaneous logging of heart rate and speed has the potential to be a reliable and powerful technique for field testing that can help in the monitoring of the horse's response to jumping effort during training and competition.

  6. Evaluation of habitat use by Rocky Mountain elk (Cervus elaphus nelsoni) in north-central New Mexico using global positioning system radio collars

    SciTech Connect

    Biggs, J.; Bennett, K.; Fresquez, P.R.

    1997-04-01

    In 1996 the authors initiated a study to identify habitat use in north-central New Mexico by Rocky Mountain elk (Cervus elaphus nelsoni) using global positioning system (GPS) radio collars. They collared six elk in the spring of 1996 with GPS radio collars programmed to obtain locational fixes every 23 h. Between April 1, 1996 and January 7, 1997, they collected >1,200 fixes with an approximately 70% observation rate. They have interfaced GPS locational fixes of elk and detailed vegetation maps using the geographical information system to provide seasonal habitat use within mountainous regions of north-central New Mexico. Based on habitat use and availability analysis, use of grass/shrub and pinon/juniper habitats was generally higher than expected during most seasons and use of forested habitats was lower than expected. Most of the collared elk remained on LANL property year-round. The authors believe the application of GPS collars to elk studies in north-central New Mexico to be a more efficient and effective method than the use of VHF (very-high frequency) radio collars.

  7. Coseismic and initial postseismic deformation from the 2004 Parkfield, California, earthquake, observed by global positioning system, electronic distance meter, creepmeters, and borehole strainmeters

    USGS Publications Warehouse

    Langbein, J.; Murray, J.R.; Snyder, H.A.

    2006-01-01

    Global Positioning System (GPS), electronic distance meter, creepmeter, and strainmeter measurements spanning the M 6.0 Parkfield, California, earthquake are examined. Using these data from 100 sec through 9 months following the main-shock, the Omori's law, with rate inversely related to time, l/t p and p ranging between 0.7 and 1.3, characterizes the time-dependent deformation during the post-seismic period; these results are consistent with creep models for elastic solids. With an accurate function of postseismic response, the coseismic displacements can be estimated from the high-rate, 1-min sampling GPS; and the coseismic displacements are approximately 75% of those estimated from the daily solutions. Consequently, fault-slip models using daily solutions overestimate coseismic slip. In addition, at 2 months and at 8 months following the mainshock, postseismic displacements are modeled as slip on the San Andreas fault with a lower bound on the moment exceeding that of the coseismic moment.

  8. Detection and measurement of land subsidence using interferometric synthetic aperture radar and Global Positioning System, San Bernardino County, Mojave Desert, California

    USGS Publications Warehouse

    Sneed, Michelle; Ikehara, Marti E.; Stork, Sylvia V.; Amelung, Falk; Galloway, Devin L.

    2003-01-01

    Land subsidence associated with ground-water-level declines has been recognized as a potential problem in parts of the Mojave Desert, California. Ground water has been the primary source of domestic, agricultural, and municipal water supplies in the desert since the early 1900s. Pumping of ground water from the Mojave River and Morongo ground-water basins in the southwestern Mojave Desert resulted in water-level declines of more than 30 meters (100 feet) between the 1950s and the 1990s. A Global Positioning System (GPS) survey of a geodetic network was used to determine the location, extent, and magnitude of vertical land-surface changes in Lucerne Valley in the Morongo ground-water basin. The GPS survey was conducted in 1998 to estimate historical elevation changes by comparing GPS-derived elevations with historical elevations (which were available for some of the monuments in the network as early as 1944) and to establish baseline values that can be used for comparisons with future GPS surveys. The GPS measurements indicated that about 600 millimeters (2 feet) [plus or minus 1,500 millimeters (5 feet)] of subsidence occurred at three of the monuments between 1969 and 1998 but that very little to no vertical change in position occurred at seven other monuments in the network. Water levels in the area of subsidence in Lucerne Valley declined about 15 meters (50 feet) during 1970-98. Interferometric synthetic aperture radar (InSAR) methods were used to characterize vertical land-surface changes in the Mojave River and Morongo ground-water basins during various intervals of time between 1992 and 1999. Interferograms, InSAR-generated displacement maps, show that subsidence ranging from 45 to 90 mm (0.15 to 0.3 ft) occurred in four areas of these two ground-water basins--the El Mirage, Lockhart-Harper Lake (dry), Newberry Springs, and Lucerne Valley areas. Some of the InSAR measurements were affected by the earthquakes at Landers and Hector Mine, California, and by

  9. Determination of land subsidence related to ground-water-level declines using Global Positioning System and leveling surveys in Antelope Valley, Los Angeles and Kern counties, California, 1992

    USGS Publications Warehouse

    Ikehara, M.E.; Phillips, S.P.

    1994-01-01

    A large-scale, land-subsidence monitoring network for Antelope Valley, California, was established, and positions and elevations for 85 stations were measured using Global Positioning System geodetic surveying in spring 1992. The 95-percent confidence (2@) level of accuracy for the elevations calculated for a multiple-constraint adjustment generally ranged from +0.010 meter (0.032 foot) to +0.024 meter (0.078 foot). The magnitudes and rates of land subsidence as of 1992 were calculated for several periods for 218 bench marks throughout Antelope Valley. The maximum measured magnitude of land subsidence that occurred between 1926 and 1992 was 6.0 feet (1.83 meters) at BM 474 near Avenue I and Sierra Highway. Measured or estimated subsidence of 2-7 feet (.61-2.l3 meters) had occurred in a 210- square-mile (542-square-kilometer) area of Antelope Valley, generally bounded by Avenue K, Avenue A, 90th Street West, and 120th Street East, during the same period. Land subsidence in Antelope Valley is caused by aquifer-system compaction, which is related to ground-water-level declines and the presence of fine-grained, compressible sediments. Comparison of potentiomethric-surface, water-level decline, and subsidence-rate maps for several periods indicated a general correlation between water-level declines and the distribution and rate of subsidence in the Lancaster ground-water subbasin. A conservative estimate of the amount of the reduction in storage capacity of the aquifer system in the Lancaster subbasin is about 50,000 acre-feet in the area that has been affected by more than one foot (.30 meters) of subsidence as of 1992. Information on the history of ground-water levels and the distribution and thickness of fine-grained compressible sediments can be used to mitigate continued land subsidence. Future monitoring of ground-water levels and land-surface elevations in subsidence-sensitive regions of Antelope Valley may be an effective means to manage land subsidence.

  10. Global Positioning System (GPS) survey of Augustine Volcano, Alaska, August 3-8, 2000: data processing, geodetic coordinates and comparison with prior geodetic surveys

    USGS Publications Warehouse

    Pauk, Benjamin A.; Power, John A.; Lisowski, Mike; Dzurisin, Daniel; Iwatsubo, Eugene Y.; Melbourne, Tim

    2001-01-01

    Between August 3 and 8,2000,the Alaska Volcano Observatory completed a Global Positioning System (GPS) survey at Augustine Volcano, Alaska. Augustine is a frequently active calcalkaline volcano located in the lower portion of Cook Inlet (fig. 1), with reported eruptions in 1812, 1882, 1909?, 1935, 1964, 1976, and 1986 (Miller et al., 1998). Geodetic measurements using electronic and optical surveying techniques (EDM and theodolite) were begun at Augustine Volcano in 1986. In 1988 and 1989, an island-wide trilateration network comprising 19 benchmarks was completed and measured in its entirety (Power and Iwatsubo, 1998). Partial GPS surveys of the Augustine Island geodetic network were completed in 1992 and 1995; however, neither of these surveys included all marks on the island.Additional GPS measurements of benchmarks A5 and A15 (fig. 2) were made during the summers of 1992, 1993, 1994, and 1996. The goals of the 2000 GPS survey were to:1) re-measure all existing benchmarks on Augustine Island using a homogeneous set of GPS equipment operated in a consistent manner, 2) add measurements at benchmarks on the western shore of Cook Inlet at distances of 15 to 25 km, 3) add measurements at an existing benchmark (BURR) on Augustine Island that was not previously surveyed, and 4) add additional marks in areas of the island thought to be actively deforming. The entire survey resulted in collection of GPS data at a total of 24 sites (fig. 1 and 2). In this report we describe the methods of GPS data collection and processing used at Augustine during the 2000 survey. We use this data to calculate coordinates and elevations for all 24 sites surveyed. Data from the 2000 survey is then compared toelectronic and optical measurements made in 1988 and 1989. This report also contains a general description of all marks surveyed in 2000 and photographs of all new marks established during the 2000 survey (Appendix A).

  11. Application of global positioning system methods for the study of obesity and hypertension risk among low-income housing residents in New York City: a spatial feasibility study.

    PubMed

    Duncan, Dustin T; Regan, Seann D; Shelley, Donna; Day, Kristen; Ruff, Ryan R; Al-Bayan, Maliyhah; Elbel, Brian

    2014-11-01

    The purpose of this study was to evaluate the feasibility of using global positioning system (GPS) methods to understand the spatial context of obesity and hypertension risk among a sample of low-income housing residents in New York City (n = 120). GPS feasibility among participants was measured with a pre- and post-survey as well as adherence to a protocol which included returning the GPS device as well as objective data analysed from the GPS devices. We also conducted qualitative interviews with 21 of the participants. Most of the sample was overweight (26.7%) or obese (40.0%). Almost one-third (30.8%) was pre-hypertensive and 39.2% was hypertensive. Participants reported high ratings of GPS acceptability, ease of use and low levels of wear-related concerns in addition to few concerns related to safety, loss or appearance, which were maintained after the baseline GPS feasibility data collection. Results show that GPS feasibility increased over time. The overall GPS return rate was 95.6%. Out of the total of 114 participants with GPS, 112 (98.2%) delivered at least one hour of GPS data for one day and 84 (73.7%) delivered at least one hour on 7 or more days. The qualitative interviews indicated that overall, participants enjoyed wearing the GPS devices, that they were easy to use and charge and that they generally forgot about the GPS device when wearing it daily. Findings demonstrate that GPS devices may be used in spatial epidemiology research in low-income and potentially other key vulnerable populations to understand geospatial determinants of obesity, hypertension and other diseases that these populations disproportionately experience.

  12. Application of global positioning system methods for the study of obesity and hypertension risk among low-income housing residents in New York City: a spatial feasibility study

    PubMed Central

    Duncan, Dustin T.; Regan, Seann D.; Shelley, Donna; Day, Kristen; Ruff, Ryan R.; Al-Bayan, Maliyhah; Elbel, Brian

    2016-01-01

    The purpose of this study was to evaluate the feasibility of using global positioning system (GPS) methods to understand the spatial context of obesity and hypertension risk among a sample of low-income housing residents in New York City (n = 120). GPS feasibility among participants was measured with a pre- and post-survey as well as adherence to a protocol which included returning the GPS device as well as objective data analysed from the GPS devices. We also conducted qualitative interviews with 21 of the participants. Most of the sample was overweight (26.7%) or obese (40.0%). Almost one-third (30.8%) was pre-hypertensive and 39.2% was hypertensive. Participants reported high ratings of GPS acceptability, ease of use and low levels of wear-related concerns in addition to few concerns related to safety, loss or appearance, which were maintained after the baseline GPS feasibility data collection. Results show that GPS feasibility increased over time. The overall GPS return rate was 95.6%. Out of the total of 114 participants with GPS, 112 (98.2%) delivered at least one hour of GPS data for one day and 84 (73.7%) delivered at least one hour on 7 or more days. The qualitative interviews indicated that overall, participants enjoyed wearing the GPS devices, that they were easy to use and charge and that they generally forgot about the GPS device when wearing it daily. Findings demonstrate that GPS devices may be used in spatial epidemiology research in low-income and potentially other key vulnerable populations to understand geospatial determinants of obesity, hypertension and other diseases that these populations disproportionately experience. PMID:25545926

  13. Match analysis of U9 and U10 english premier league academy soccer players using a global positioning system: relevance for talent identification and development.

    PubMed

    Goto, Heita; Morris, John G; Nevill, Mary E

    2015-04-01

    The purpose of this study was to examine the match activity profile of U9 and U10 elite soccer players and to establish if there were any differences between players who were subsequently retained or released by their clubs. Such information should prove valuable in the design of training programs for these very young players and in the talent identification and development process. A Global Positioning System was used to analyze 2-4 interacademy 6-a-side matches of English Premier League Academy players (U9: N = 22 and U10: N = 12) who trained 3 times a week (4.5 hours). Speed zones were created based on 5 and 10-m sprint times, and an independent sample t-test was employed for a statistical analysis. Both squads covered ∼4,000 m in total or ∼4,700 m·h during a match (p = NS between squads), with the U10 squad tending to cover a greater distance at moderate (p = 0.10) and high speeds (p = 0.08) than the U9 squad. Retained group covered a greater distance than released group (retained vs. released: 4,478 ± 513 m vs. 4,091 ± 462 m, p < 0.05) during a match and covered a greater distance during low-speed running in absolute (1,226 ± 259 m vs. 1,005 ± 221 m, p < 0.05) and relative (1,325 ± 235 m·h vs. 1,132 ± 210 m·h, p < 0.05) terms. Thus, U9 and U10 players cover over 4000 m in match play, and those players who are retained by academies cover a greater distance in total and at low speeds (2.1-3.1 m·s). This information may support the preparation of squad training programs and the talent identification and development process.

  14. The use of Global Positioning System units and ArcGIS Online to engage K-12 Students in Research Being Done in their Local Communities

    NASA Astrophysics Data System (ADS)

    Butcher, C. E.; Sparrow, E. B.; Clucas, T.

    2015-12-01

    Incorporating K-12 students in scientific research processes and opportunities in their communities is a great way to bridge the gap between research and education and to start building science research capacity at an early age. One goal of the Experimental Program to Stimulate Competitive Research (EPSCoR) Alaska Adapting to Changing Environments project is to engage the local community in the research as well as to share results with the people. By giving K-12 students Global Positioning System (GPS) units, and allowing them to collect and map their own data, they are being exposed to some of the research methods being used by scientists in the Alaska ACE project. This hands-on, minds-on method has been successfully used in formal education settings such as a Junior High School classroom in Nuiqsut, Alaska as well as in informal education settings such as summer camps in Barrow, Alaska and Kenai, Alaska. The students progress from mapping by hand to collecting location data with their GPS units and cameras, and imputing this information into ArcGIS Online to create map products. The data collected were from sites ranging from important places in the community to sites visited during summer camps, with students reflecting on data and site significance. Collecting data, using technology, and creating map products contribute to science skills and practices students need to conduct research of their own and to understand research being done around them. The goal of this education outreach implementation is to bring students closer to the research, understand the process of science, and have the students continue to collect data and contribute to research in their communities. Support provided for this work from the Alaska EPSCoR NSF Award #OIA-1208927 and the state of Alaska is gratefully acknowledged.

  15. Global positioning system & Google Earth in the investigation of an outbreak of cholera in a village of Bengaluru Urban district, Karnataka

    PubMed Central

    Masthi, N.R. Ramesh; Madhusudan, M.; Puthussery, Yannick P.

    2015-01-01

    Background & objectives: The global positioning system (GPS) technology along with Google Earth is used to measure (spatial map) the accurate distribution of morbidity, mortality and planning of interventions in the community. We used this technology to find out its role in the investigation of a cholera outbreak, and also to identify the cause of the outbreak. Methods: This study was conducted in a village near Bengaluru, Karnataka in June 2013 during a cholera outbreak. House-to-house survey was done to identify acute watery diarrhoea cases. A hand held GPS receiver was used to record north and east coordinates of the households of cases and these values were subsequently plotted on Google Earth map. Water samples were collected from suspected sources for microbiological analysis. Results: A total of 27 cases of acute watery diarrhoea were reported. Fifty per cent of cases were in the age group of 14-44 yr and one death was reported. GPS technology and Google Earth described the accurate location of household of cases and spot map generated showed clustering of cases around the suspected water sources. The attack rate was 6.92 per cent and case fatality rate was 3.7 per cent. Water samples collected from suspected sources showed the presence of Vibrio cholera O1 Ogawa. Interpretation & conclusions: GPS technology and Google Earth were easy to use, helpful to accurately pinpoint the location of household of cases, construction of spot map and follow up of cases. Outbreak was found to be due to contamination of drinking water sources. PMID:26658586

  16. Contemporary tectonic deformation of the Basin and Range province, western United States: 10 years of observation with the Global Positioning System

    USGS Publications Warehouse

    Hammond, W.C.; Thatcher, W.

    2004-01-01

    We have estimated patterns and rates of crustal movement across 800 km of the Basin and Range at ???39?? north latitude with Global Positioning System surveys in 1992, 1996, 1998, and 2002. The total rate of motion tangent to the small circle around the Pacific-North America pole of rotation is 10.4 ?? 1.0 mm/yr, and motion normal to this small circle is 3.9 ?? 0.9 mm/yr compared to the east end of our network. On the Colorado Plateau the east end of our network moves by ???1-2 mm/yr westerly with respect to North America. Transitions in strain rates delimit six major tectonic domains within the province. These deformation zones coincide with areas of modern seismicity and are, from east to west, (1) east-west extension in the Wasatch Fault zone, (2) low rate east-west extension centered near the Nevada-Utah border, (3) low rate east-west contraction between 114.7??W and 117.9??W, (4) extension normal to and strike-slip motion across the N10??E striking Central Nevada Seismic Zone, (5) right lateral simple shear oriented N13??W inside the Walker Lane Belt, and (6) shear plus extension near the Sierra Nevada frontal faults. Concentration of shear and dilatational deformation across the three westernmost zones suggests that the Walker Lane Belt lithosphere is rheologically weak. However, we show that linear gradients in viscosity and gravitational potential energy can also effectively concentrate deformation. In the Basin and Range, gradients in gravitational potential are spatially anticorrelated with dilatational strain rates, consistent with the presence of horizontal variations in viscosity of the lithosphere.

  17. The validity and reliability of a global positioning satellite system device to assess speed and repeated sprint ability (RSA) in athletes.

    PubMed

    Barbero-Alvarez, José C; Coutts, Aaron; Granda, Juan; Barbero-Alvarez, Verónica; Castagna, Carlo

    2010-03-01

    There is a limited understanding of the validity and reliability of commercially available global positioning satellite (GPS) devices for assessing repeated sprint performance in athletes. The aims of this study were to assess the convergent validity and the test-retest reliability of a GPS device for measuring repeated sprint ability test (RSAT) variables. Two groups participated in this study, a group of 21 physical education students (age: 20.2+/-2.3 years, stature: 1.75+/-0.42 m, body mass: 68.0+/-6.8kg) and a second group 14 elite junior soccer players (age: 14.5+/-1.2 years, stature: 1.60+/-0.09 m, body mass: 57.7+/-3.8kg) volunteered to participate in this study. Convergent validity was assessed as the correlation between sprint performance (15 and 30-m) using both timing lights and a portable GPS device during a RSAT (7 x 30-m sprints with 30-s of active recovery). The 7 x 30-m RSAT test-retest reliability using GPS device was assessed in elite junior soccer players repeating the test 1 week apart and expressing reliability as a coefficient of variation. Results showed a strong correlation between peak speed measures with the GPS device and RSAT performance measured with timing lights for the 15-m (r(2)=0.87, p<0.001, N=147) and 30-m (r(2)=0.94, p<0.001, N=147) splits, respectively. There was a low coefficient of variation for summated maximal speed (1.7%) and peak speed (1.2%) during the 7 x 30-m RSAT, but high variation for the percentage decrement score (36.2%). These results provide evidence to support the use of the GPS device as an alternative measure to assess repeated sprint performance but suggest a percentage decrement score is not a reliable measure of RSAT performance.

  18. Global Positioning System constraints on crustal deformation before and during the 21 February 2008 Wells, Nevada M6.0 earthquake

    USGS Publications Warehouse

    Hammond, William C.; Blewitt, Geoffrey; Kreemer, Corné; Murray-Moraleda, Jessica R.; Svarc, Jerry L.; dePolo, Craig M.; LaPointe, Daphne D.

    2011-01-01

    Using Global Positioning System (GPS) data from permanent sites and U.S. Geological Survey (USGS) campaign data we have estimated co-seismic displacements and secular background crustal deformation patterns associated with the 21 February 2008 Wells Nevada earthquake. Estimated displacements at nearby permanent GPS sites ELKO (84 km distant) and GOSH (81 km distant) are 1.0±0.2 mm and 1.1±0.3 mm, respectively. The magnitude and direction are in agreement with those predicted from a rupture model based on InSAR measurements of the near-field co-seismic surface displacement. Analysis of long GPS time series (>10 years) from the permanent sites within 250 km of the epicenter indicate the eastern Nevada Basin and Range undergoes steady tectonic transtension with rates on the order of 1 mm/year over approximately 250 km. The azimuth of maximum horizontal crustal extension is consistent with the azimuth of the Wells earthquake co-seismic slip vector. The orientation of crustal shear is consistent with deformation associated with Pacific/North America plate boundary relative motion seen elsewhere in the Basin and Range. In response to the event, we deployed a new GPS site with the capability to telemeter high rate, low latency data that will in the future allow for rapid estimation of surface displacement should aftershocks or postseismic deformations occur. We estimated co-seismic displacements using campaign GPS data collected before and after the event, however in most cases their uncertainties were larger than the offsets. Better precision in co-seismic displacement could have been achieved for the campaign sites if they had been surveyed more times or over a longer interval to better estimate their pre-event velocity.

  19. Global Positioning System Derived Performance Measures Are Responsive Indicators of Physical Activity, Disease and the Success of Clinical Treatments in Domestic Dogs

    PubMed Central

    Bruno, Elizabeth A.; Guthrie, James W.; Ellwood, Stephen A.; Mellanby, Richard J.; Clements, Dylan N.

    2015-01-01

    Objective To assess the use of Global Positioning System receiver (GPS) derived performance measures for differentiating between: 1) different outdoor activities in healthy dogs; 2) healthy dogs and those with osteoarthritis; 3) osteoarthritic dogs before and after treatment with non-steroidal anti-inflammatory analgesia. Design Prospective study. Animals Ten healthy dogs and seven dogs with osteoarthritis of the elbow joint (OA dogs). Procedure Healthy dogs were walked on a standard route on-lead, off-lead and subjected to playing activity (chasing a ball) whilst wearing a GPS collar. Each dog was walked for five consecutive days. Dogs with OA were subjected to a single off-lead walk whilst wearing a GPS collar, and then administered oral Carprofen analgesia daily for two weeks. OA dogs were then subjected to the same walk, again wearing a GPS collar. Results GPS derived measures of physical performance could differentiate between on-lead activity, off-lead activity and playing activity in healthy dogs, and between healthy dogs and OA dogs. Variation in the performance measures analysed was greater between individual dogs than for individual dogs on different days. Performance measures could differentiate healthy dogs from OA dogs. OA Dogs treated with Carprofen analgesia showed improvements in their physical performance, which returned to values indistinguishable from those of healthy dogs on nearly all the measures assessed. Conclusions and Clinical Relevance GPS derived measures of physical performance in dogs are objective, easy to quantify, and can be used to gauge the effects of disease and success of clinical treatments. Specific stimuli can be used to modulate physical performance beyond the self-governed boundaries that dogs will naturally express when allowed to exercise freely without stimulation. PMID:25692761

  20. Quantifying the physical activity energy expenditure of commuters using a combination of global positioning system and combined heart rate and movement sensors

    PubMed Central

    Costa, Silvia; Ogilvie, David; Dalton, Alice; Westgate, Kate; Brage, Søren; Panter, Jenna

    2015-01-01

    Background Active commuting may help to increase adults' physical activity levels. However, estimates of its energy cost are derived from a small number of studies which are laboratory-based or use self-reported measures. Methods Adults working in Cambridge (UK) recruited through a predominantly workplace-based strategy wore combined heart rate and movement sensors and global positioning system (GPS) devices for one week, and completed synchronous day-by-day travel diaries in 2010 and 2011. Commuting journeys were delineated using GPS data, and metabolic intensity (standard metabolic equivalents; MET) was derived and compared between journey types using mixed-effects linear regression. Results 182 commuting journeys were included in the analysis. Median intensity was 1.28 MET for car journeys; 1.67 MET for bus journeys; 4.61 MET for walking journeys; 6.44 MET for cycling journeys; 1.78 MET for journeys made by car in combination with walking; and 2.21 MET for journeys made by car in combination with cycling. The value for journeys made solely by car was significantly lower than those for all other journey types (p < 0.04). On average, 20% of the duration of journeys incorporating any active travel (equating to 8 min) was spent in moderate-to-vigorous physical activity (MVPA). Conclusions We have demonstrated how GPS and activity data from a free-living sample can be used simultaneously to provide objective estimates of commuting energy expenditure. On average, incorporating walking or cycling into longer journeys provided over half the weekly recommended activity levels from the commute alone. This may be an efficient way of achieving physical activity guidelines and improving population health. PMID:26441297

  1. Global Status, Intra-Institutional Stratification and Organizational Segmentation: A Time-Dynamic Tobit Analysis of ARWU Position among U.S. Universities

    ERIC Educational Resources Information Center

    Cantwell, Brendan; Taylor, Barrett J.

    2013-01-01

    Ranking systems such as "The Times Higher Education's World University Rankings" and Shanghai Jiao Tong University's "Academic Rankings of World Universities" simultaneously mark global status and stimulate global academic competition. As international ranking systems have become more prominent, researchers have begun to examine whether global…

  2. Perceived spatial stigma, body mass index and blood pressure: a global positioning system study among low-income housing residents in New York City.

    PubMed

    Duncan, Dustin T; Ruff, Ryan R; Chaix, Basile; Regan, Seann D; Williams, James H; Ravenell, Joseph; Bragg, Marie A; Ogedegbe, Gbenga; Elbel, Brian

    2016-01-01

    Previous research has highlighted the salience of spatial stigma on the lives of low-income residents, but has been theoretical in nature and/or has predominantly utilised qualitative methods with limited generalisability and ability to draw associations between spatial stigma and measured cardiovascular health outcomes. The primary objective of this study was to evaluate relationships between perceived spatial stigma, body mass index (BMI), and blood pressure among a sample of low-income housing residents in New York City (NYC). Data come from the community-based NYC Low-income Housing, Neighborhoods and Health Study. We completed a crosssectional analysis with survey data, which included the four items on spatial stigma, as well objectively measured BMI and blood pressure data (analytic n=116; 96.7% of the total sample). Global positioning systems (GPS) tracking of the sample was conducted for a week. In multivariable models (controlling for individual-level age, gender, race/ethnicity, education level, employment status, total household income, neighborhood percent non-Hispanic Black and neighborhood median household income) we found that participants who reported living in an area with a bad neighborhood reputation had higher BMI (B=4.2, 95%CI: -0.01, 8.3, P=0.051), as well as higher systolic blood pressure (B=13.2, 95%CI: 3.2, 23.1, P=0.01) and diastolic blood pressure (B=8.5, 95%CI: 2.8, 14.3, P=0.004). In addition, participants who reported living in an area with a bad neighborhood reputation had increased risk of obesity/overweight [relative risk (RR)=1.32, 95%CI: 1.1, 1.4, P=0.02) and hypertension/pre-hypertension (RR=1.66, 95%CI: 1.2, 2.4, P=0.007). However, we found no differences in spatial mobility (based GPS data) among participants who reported living in neighborhoods with and without spatial stigma (P>0.05). Further research is needed to investigate how placebased stigma may be associated with impaired cardiovascular health among individuals in

  3. Perceived spatial stigma, body mass index and blood pressure: a global positioning system study among low-income housing residents in New York City.

    PubMed

    Duncan, Dustin T; Ruff, Ryan R; Chaix, Basile; Regan, Seann D; Williams, James H; Ravenell, Joseph; Bragg, Marie A; Ogedegbe, Gbenga; Elbel, Brian

    2016-05-31

    Previous research has highlighted the salience of spatial stigma on the lives of low-income residents, but has been theoretical in nature and/or has predominantly utilised qualitative methods with limited generalisability and ability to draw associations between spatial stigma and measured cardiovascular health outcomes. The primary objective of this study was to evaluate relationships between perceived spatial stigma, body mass index (BMI), and blood pressure among a sample of low-income housing residents in New York City (NYC). Data come from the community-based NYC Low-income Housing, Neighborhoods and Health Study. We completed a crosssectional analysis with survey data, which included the four items on spatial stigma, as well objectively measured BMI and blood pressure data (analytic n=116; 96.7% of the total sample). Global positioning systems (GPS) tracking of the sample was conducted for a week. In multivariable models (controlling for individual-level age, gender, race/ethnicity, education level, employment status, total household income, neighborhood percent non-Hispanic Black and neighborhood median household income) we found that participants who reported living in an area with a bad neighborhood reputation had higher BMI (B=4.2, 95%CI: -0.01, 8.3, P=0.051), as well as higher systolic blood pressure (B=13.2, 95%CI: 3.2, 23.1, P=0.01) and diastolic blood pressure (B=8.5, 95%CI: 2.8, 14.3, P=0.004). In addition, participants who reported living in an area with a bad neighborhood reputation had increased risk of obesity/overweight [relative risk (RR)=1.32, 95%CI: 1.1, 1.4, P=0.02) and hypertension/pre-hypertension (RR=1.66, 95%CI: 1.2, 2.4, P=0.007). However, we found no differences in spatial mobility (based GPS data) among participants who reported living in neighborhoods with and without spatial stigma (P>0.05). Further research is needed to investigate how placebased stigma may be associated with impaired cardiovascular health among individuals in

  4. Strengths and weaknesses of Global Positioning System (GPS) data-loggers and semi-structured interviews for capturing fine-scale human mobility: findings from Iquitos, Peru.

    PubMed

    Paz-Soldan, Valerie A; Reiner, Robert C; Morrison, Amy C; Stoddard, Steven T; Kitron, Uriel; Scott, Thomas W; Elder, John P; Halsey, Eric S; Kochel, Tadeusz J; Astete, Helvio; Vazquez-Prokopec, Gonzalo M

    2014-06-01

    Quantifying human mobility has significant consequences for studying physical activity, exposure to pathogens, and generating more realistic infectious disease models. Location-aware technologies such as Global Positioning System (GPS)-enabled devices are used increasingly as a gold standard for mobility research. The main goal of this observational study was to compare and contrast the information obtained through GPS and semi-structured interviews (SSI) to assess issues affecting data quality and, ultimately, our ability to measure fine-scale human mobility. A total of 160 individuals, ages 7 to 74, from Iquitos, Peru, were tracked using GPS data-loggers for 14 days and later interviewed using the SSI about places they visited while tracked. A total of 2,047 and 886 places were reported in the SSI and identified by GPS, respectively. Differences in the concordance between methods occurred by location type, distance threshold (within a given radius to be considered a match) selected, GPS data collection frequency (i.e., 30, 90 or 150 seconds) and number of GPS points near the SSI place considered to define a match. Both methods had perfect concordance identifying each participant's house, followed by 80-100% concordance for identifying schools and lodgings, and 50-80% concordance for residences and commercial and religious locations. As the distance threshold selected increased, the concordance between SSI and raw GPS data increased (beyond 20 meters most locations reached their maximum concordance). Processing raw GPS data using a signal-clustering algorithm decreased overall concordance to 14.3%. The most common causes of discordance as described by a sub-sample (n=101) with whom we followed-up were GPS units being accidentally off (30%), forgetting or purposely not taking the units when leaving home (24.8%), possible barriers to the signal (4.7%) and leaving units home to recharge (4.6%). We provide a quantitative assessment of the strengths and weaknesses of

  5. Active crustal deformation across the Basin and Range province, western United States, measured with the Global Positioning System, 1992-2002

    NASA Astrophysics Data System (ADS)

    Hammond, W.; Thatcher, W.

    2003-04-01

    The Basin and Range province of the western United States is a region of active tectonic extension and dextral shear, accommodating roughly 25% of the motion between non-deforming North America (NA) and the Pacific Plate (PA). The orientation of dextral shear is consistent with that of NA/PA relative plate motion, suggesting that this high elevation interior province is an important part of the plate boundary system. We present an analysis of Global Positioning System (GPS) data collected from 1992 to 2002. An 800 km long network of campaign-style geodetic benchmarks extends from east of the Wasatch fault zone (WFZ) in central Utah to west of the Genoa fault zone and Lake Tahoe in the northern Sierra Nevada mountains. From the new data collected in September 2002 and from data collected in 1992, 1996, and 1998, velocities have been estimated at 92 GPS sites, nearly double the number previously presented by Thatcher et al. [1999]. This new data reduces the uncertainty in site velocities and increases the spatial detail compared to earlier results, and now allows resolution of distinct domains in the tensor strain rate field. To process the data we use the GIPSY/OASIS and Quasi-Observation Combination Analysis (Dong et al. [1998]) software packages and incorporate data from continuously recording GPS stations in California and Nevada. The results show that most of the approximately 12 mm/yr of Sierra Nevada block motion is accommodated by right lateral shear and extensional deformation concentrated in the westernmost 200 km of Nevada, in the vicinity of the Walker Lane (WL). A lesser amount of velocity variation (roughly 3 mm/yr) is localized at the easternmost edge of the network, in the vicinity of the Wasatch Fault Zone (WFZ). Estimates of tensor strain rates show transitions in the style of deformation. Near the WFZ only uniaxial, roughly east-west extension can be resolved. Between longitude -112 and -117.5 no deformation is resolvable. Near longitude -118, in

  6. Strengths and Weaknesses of Global Positioning System (GPS) Data-Loggers and Semi-structured Interviews for Capturing Fine-scale Human Mobility: Findings from Iquitos, Peru

    PubMed Central

    Paz-Soldan, Valerie A.; Reiner, Robert C.; Morrison, Amy C.; Stoddard, Steven T.; Kitron, Uriel; Scott, Thomas W.; Elder, John P.; Halsey, Eric S.; Kochel, Tadeusz J.; Astete, Helvio; Vazquez-Prokopec, Gonzalo M.

    2014-01-01

    Quantifying human mobility has significant consequences for studying physical activity, exposure to pathogens, and generating more realistic infectious disease models. Location-aware technologies such as Global Positioning System (GPS)-enabled devices are used increasingly as a gold standard for mobility research. The main goal of this observational study was to compare and contrast the information obtained through GPS and semi-structured interviews (SSI) to assess issues affecting data quality and, ultimately, our ability to measure fine-scale human mobility. A total of 160 individuals, ages 7 to 74, from Iquitos, Peru, were tracked using GPS data-loggers for 14 days and later interviewed using the SSI about places they visited while tracked. A total of 2,047 and 886 places were reported in the SSI and identified by GPS, respectively. Differences in the concordance between methods occurred by location type, distance threshold (within a given radius to be considered a match) selected, GPS data collection frequency (i.e., 30, 90 or 150 seconds) and number of GPS points near the SSI place considered to define a match. Both methods had perfect concordance identifying each participant's house, followed by 80–100% concordance for identifying schools and lodgings, and 50–80% concordance for residences and commercial and religious locations. As the distance threshold selected increased, the concordance between SSI and raw GPS data increased (beyond 20 meters most locations reached their maximum concordance). Processing raw GPS data using a signal-clustering algorithm decreased overall concordance to 14.3%. The most common causes of discordance as described by a sub-sample (n = 101) with whom we followed-up were GPS units being accidentally off (30%), forgetting or purposely not taking the units when leaving home (24.8%), possible barriers to the signal (4.7%) and leaving units home to recharge (4.6%). We provide a quantitative assessment of the strengths and

  7. Globalization and global health.

    PubMed

    Berlinguer, G

    1999-01-01

    Along with the positive or negative consequences of the globalization of health, we can consider global health as a goal, responding to human rights and to common interests. History tells us that after the "microbial unification" of the world, which began in 1492, over three centuries elapsed before the recognition of common risks and attempts to cope with them in a cross-boundary effort. In the 19th and 20th centuries, the struggle against epidemics united countries, world health became a common goal, and considerable results were achieved. However, in recent decades the notion of health as a cornerstone of economic development has been replaced by the idea that public health and health services are an obstacle to the wealth of nations. Meanwhile, new common threats are growing: among them, the exacerbation of old infections and emergence of new ones, the impact of environmental changes, drug traffic on a world scale, and destructive and self-destructive violence. New and stronger empirical motives relate the interests of peoples to universal rights and to global health. The author concludes with some proposals for policies.

  8. Spatially Variable Creep Rate on the Bartlett Springs and Maacama Faults, Northern California, Estimated via Bayesian Inversion of Global Positioning System Data

    NASA Astrophysics Data System (ADS)

    Murray, J. R.; Svarc, J. L.; Minson, S. E.

    2012-12-01

    Fault creep, if it extends to seismogenic depths, can reduce the maximum expected magnitude of earthquakes on a fault. The San Andreas Fault System in northern California consists of three main strands in a 100 km wide zone, the San Andreas (SAF), Maacama (MF), and Bartlett Springs (BSF). Creep has been observed on the MF and BSF using alinement arrays. An early study using Global Positioning System (GPS) data suggested that the BSF creeps at ˜8 mm/yr at all seismogenic depths, but only two GPS sites were available near the BSF at that time. Our goal is to infer the rate and spatial extent of interseismic creep on the seismogenic portion (above ˜15 km) of the MF and BSF faults and the slip rates on all three faults below that depth from GPS data. Equally important, we aim to provide a realistic measure of the uncertainties on these estimated parameters while avoiding the assumption of spatial smoothing. Smoothing is often used to regularize underdetermined inversions but can lead to spurious results. We use continuous GPS data from the Bay Area Regional Deformation network and the Plate Boundary Observatory augmented by survey-mode GPS (SGPS) data collected by USGS beginning in 2005 along the BSF and since 2009 near the MF. The locations of SGPS sites provide dense spatial coverage within 10 km of the BSF and MF to better image creep in the upper several kilometers. Fault-perpendicular profiles of the fault-parallel GPS velocity component across the region show distinct steps at the BSF that are indicative of near-surface creep at rates that decrease from ˜8 mm/yr ˜10 km northwest of Lake Pillsbury to ˜4 mm/yr at Lake Pillsbury and continue to decrease southeast of there. This is generally consistent with alinement array measurements at Lake Pillsbury and at Newman Springs (˜35 km southeast). Although less well-constrained given their shorter observation history, GPS velocities near the MF suggest ˜5 mm/yr of near-surface creep, consistent with alinement

  9. Detection and Measurement of Land Subsidence Using Global Positioning System and Interferometric Synthetic Aperture Radar, Coachella Valley, California, 1998-2000

    USGS Publications Warehouse

    Sneed, Michelle; Stork, Sylvia V.; Ikehara, Marti E.

    2002-01-01

    Land subsidence associated with ground-water-level declines has been recognized as a potential problem in Coachella Valley, California. Since the early 1920s, ground water has been a major source of agricultural, municipal, and domestic supply in the valley. Pumping of ground water resulted in water-level declines as large as 15 meters (50 feet) through the late 1940s. In 1949, the importation of Colorado River water to the lower Coachella Valley began, resulting in a reduction in ground-water pumping and a recovery of water levels during the 1950s through the 1970s. Since the late 1970s, demand for water in the valley has exceeded deliveries of imported surface water, resulting in increased pumping and associated ground-water-level declines and, consequently, an increase in the potential for land subsidence caused by aquifer-system compaction. The location, extent, and magnitude of the vertical land-surface changes in Coachella Valley between 1998 and 2000 were determined using Global Positioning System (GPS) and interferometric synthetic aperture radar (InSAR) methods. GPS measurements made at 15 geodetic monuments in the lower Coachella Valley indicate that -34 to +60 millimeters ? 45 millimeters (-0.11 to +0.20 foot ? 0.15 foot) of vertical change in the land surface occurred during the 2-year period. Changes at three of the monuments exceeded the maximum uncertainty of ? 45 millimeters (? 0.15 foot) at the 95-percent confidence level, which indicates that small amounts of uplift occurred at these monuments between October 1998 and August 2000. Water-level measurements made at wells near the three uplifted monuments during this 2-year period indicate that the water levels fluctuate seasonally; water-level measurements made at these wells in September 1998 and September 2000 indicate that the water levels rose slightly near two monuments and declined slightly near the third. The relation between the seasonally fluctuating, but fairly stable, water levels between

  10. Impact of Ionization DEPLETIONS/TEC Bite-Outs of Equatorial Plasma Structures on Transionospheric Satellite Signals Using Global Positioning System (GPS)

    NASA Astrophysics Data System (ADS)

    Das, Tanmay

    2016-07-01

    This paper represents the impact of ionization depletions/TEC bite-outs of equatorial plasma structures on transionospheric satellite signals received from Calcutta (latitude: 22.58oN, longitude: 88.38oE geographic; 32oN magnetic dip) is situated near the northern crest of the equatorial ionization anomaly (EIA) in the Indian longitude sector, using Global Positioning System (GPS) during the equinoctial months of February-April 2011, August-October, 2011 and February-April 2012. It is observed that when a bubble moves across a satellite link, scintillations and ionization are usually encountered. The apparent duration of the bite-outs may be different from the true east-west duration, as observed with geostationary links, because of the presence of a relative velocity between the irregularity cloud and the satellite. The trajectory of a GPS satellite plays a vital role in observing the bubble characteristics. The distributions of amplitude and the parameters characterizing the ionization depletions, namely, the duration, depth and the leading and trailing edge slopes of the bubbles have been obtained during the same equinoctial months of 2011 and 2012. It is evident that the range error, extent of the bubble and ionization gradients measured in these equinoctial months of the equatorial region provides the worst case figures for system designers. The high range error (~ 3-4 m) is observed during these equinoctial months. The statistical distribution of the TEC depletions showed some significant results. Out of 29 bite-outs in February-April, 2011 equinox, the maximum amplitude was found to be about 23.25 TECU with a median depletion of about 5.92 TECU. The maximum amplitude corresponds to a range error of about 3.7 m at GPS L1 frequency. The majority of the bubbles were found to have observed duration between 10-20 minutes with a maximum of 28.14 minutes. The median value of actual duration 2.37 minutes translates to nearly 150sec of possible satellite signal

  11. [Prevalence of various pneumo-allergens among the positives in global in vitro diagnostic tests for allergy; possible importance of restricted mixtures].

    PubMed

    Dumontet, M

    1993-05-01

    With in vitro utilization of allergenic extracts' mixes, for 67 positive serums to Phadiatop or Allergy Screen, the prevalence of positivity is increased to moulds (6%), grass pollen allergens (34%), ragweed pollen allergens (13%) and tree pollens (12%). Moreover prevalence is 67% to D. pteronyssinus, 7.5% to Cockroaches and 25% to domestic mammals. At least 20% of positive serums are bisensible and 10% polysensible, which leads to do broader testing.

  12. Re-positioning the role of traditional, complementary and alternative medicine as essential health knowledge in global health: do they still have a role to play?

    PubMed

    Hollenberg, Daniel; Zakus, David; Cook, Tim; Xu, Xu Wei

    2008-01-01

    Traditional, complementary and alternative medicine (TCAM), drawn from indigenous medical and/or healing knowledge systems from around the world, has for the last 30 years been recognized by the World Health Organization (WHO) as providing culturally acceptable, affordable and sustainable primary healthcare. TCAM knowledge has been known for some time to assist with birthing practices, acute injuries, infectious diseases and parasites. Although the focus on TCAM began in earnest by the WHO in 1978, and was re-emphasized between 2002 and 2008, TCAM has for the most part been overlooked in large-scale international health programs. This paper follows recent global interest in TCAM and examines notable developments that have specific relevance for TCAM integration in global primary healthcare. Drawing on established work by Bodeker and others, we focus on how TCAM is used in the context of health promotion, disease prevention and the reduction of infectious diseases. Specific examples include the use of TCAM practitioners for HIV/AIDS prevention awareness and direct treatment of AIDS-related symptoms; the use of TCAM herbs for the treatment of malaria and the use of home herbal gardens for health maintenance. The final contribution of the paper helps to theorize inherent challenges and possible solutions to integrating TCAM into global health that have not been widely discussed to date. PMID:19550163

  13. Re-positioning the role of traditional, complementary and alternative medicine as essential health knowledge in global health: do they still have a role to play?

    PubMed

    Hollenberg, Daniel; Zakus, David; Cook, Tim; Xu, Xu Wei

    2008-01-01

    Traditional, complementary and alternative medicine (TCAM), drawn from indigenous medical and/or healing knowledge systems from around the world, has for the last 30 years been recognized by the World Health Organization (WHO) as providing culturally acceptable, affordable and sustainable primary healthcare. TCAM knowledge has been known for some time to assist with birthing practices, acute injuries, infectious diseases and parasites. Although the focus on TCAM began in earnest by the WHO in 1978, and was re-emphasized between 2002 and 2008, TCAM has for the most part been overlooked in large-scale international health programs. This paper follows recent global interest in TCAM and examines notable developments that have specific relevance for TCAM integration in global primary healthcare. Drawing on established work by Bodeker and others, we focus on how TCAM is used in the context of health promotion, disease prevention and the reduction of infectious diseases. Specific examples include the use of TCAM practitioners for HIV/AIDS prevention awareness and direct treatment of AIDS-related symptoms; the use of TCAM herbs for the treatment of malaria and the use of home herbal gardens for health maintenance. The final contribution of the paper helps to theorize inherent challenges and possible solutions to integrating TCAM into global health that have not been widely discussed to date.

  14. Detection and Measurement of Land Subsidence Using Global Positioning System Surveying and Interferometric Synthetic Aperture Radar, Coachella Valley, California, 1996-2005

    USGS Publications Warehouse

    Sneed, Michelle; Brandt, Justin T.

    2007-01-01

    Land subsidence associated with ground-water-level declines has been investigated by the U.S. Geological Survey in the Coachella Valley, California, since 1996. Ground water has been a major source of agricultural, municipal, and domestic supply in the valley since the early 1920s. Pumping of ground water resulted in water-level declines as large as 15 meters (50 feet) through the late 1940s. In 1949, the importation of Colorado River water to the southern Coachella Valley began, resulting in a reduction in ground-water pumping and a recovery of water levels during the 1950s through the 1970s. Since the late 1970s, demand for water in the valley has exceeded deliveries of imported surface water, resulting in increased pumping and associated ground-water-level declines and, consequently, an increase in the potential for land subsidence caused by aquifer-system compaction. Global Positioning System (GPS) surveying and interferometric synthetic aperture radar (InSAR) methods were used to determine the location, extent, and magnitude of the vertical land-surface changes in the southern Coachella Valley. GPS measurements made at 13 geodetic monuments in 1996 and in 2005 in the southern Coachella Valley indicate that the elevation of the land surface had a net decline of 333 to 22 millimeters ?58 millimeters (1.1 to 0.07 foot ?0.19 foot) during the 9-year period. Changes at 10 of the 13 monuments exceeded the maximum uncertainty of ?58 millimeters (?0.19 foot) at the 95-percent confidence level, indicating that subsidence occurred at these monuments between June 1996 and August 2005. GPS measurements made at 20 geodetic monuments in 2000 and in 2005 indicate that the elevation of the land surface changed -312 to +25 millimeters ?42 millimeters (-1.0 to +0.08 foot ?0.14 foot) during the 5-year period. Changes at 14 of the 20 monuments exceeded the maximum uncertainty of ?42 millimeters (?0.14 foot) at the 95-percent confidence level, indicating that subsidence occurred at

  15. Detection and measurement of land subsidence using Global Positioning System and interferometric synthetic aperture radar, Coachella Valley, California, 1996-98

    USGS Publications Warehouse

    Sneed, Michelle; Ikehara, Marti E.; Galloway, D.L.; Amelung, Falk

    2001-01-01

    Land subsidence associated with ground-water-level declines has been recognized as a potential problem in Coachella Valley, California. Since the early 1920s, ground water has been a major source of agricultural, municipal, and domestic supply in the valley, resulting in water-level declines as large as 15 meters (50 feet) through the late 1940s. In 1949, the importation of Colorado River water to the lower Coachella Valley began, resulting in a reduction in ground-water pumping and a recovery of water levels from the 1950s through the 1970s. Since the late 1970s, the demand for water in the valley has exceeded the deliveries of imported surface water, again resulting in increased pumping and ground-water-level declines. The magnitude and temporal occurrence of land subsidence in the lower Coachella Valley are not well known; data are sparse and accuracy varies. Also, the area is tectonically active and has subsided during the past several million years, which further complicates interpretations of the data. Land-surface-elevation data have been collected by many agencies using various methods and different geographic scales; because of this, the -150 millimeters (-0.5 foot) of subsidence determined for the southern parts of the valley for 1930-96 may have a possible error of plus or minus (?)90 millimeters (?0.3 foot). The location, extent, and magnitude of vertical land-surface changes from 1996 to 1998 were determined using Global Positioning System (GPS) and interferometric synthetic aperture radar (InSAR) methods. GPS measurements for 14 monuments in the lower Coachella Valley indicate that the vertical land-surface changes from 1996 to 1998 ranged from -13 to -67 millimeters ? 40 millimeters (-0.04 to -0.22 foot ?0.13 foot). Changes at seven of the monuments exceeded the measurement error of ?40 millimeters (?0.13 foot), which indicates that small amounts of land subsidence occurred at these monuments between 1996 and 1998. Some of the water levels measured

  16. Exploration through a Global Lens: Integrating the NCSS "Position Statement on the Columbian Quincentenary" into the Age of Exploration Instructional Unit.

    ERIC Educational Resources Information Center

    Shively, James M.; VanFossen, Phillip J.

    1993-01-01

    Presents six classroom activities to be used with a unit on the European exploration period. Links the activities to the themes presented in the Position Statement on the Columbian Quincentenary published by the National Council for the Social Studies. Includes recommended teaching procedures and instructional materials. (CFR)

  17. Cardiovascular risk factors and global risk of fatal cardiovascular disease are positively correlated between partners of 802 married couples from different European countries. Report from the IMMIDIET project.

    PubMed

    Di Castelnuovo, Augusto; Quacquaruccio, Gianni; Arnout, Jozef; Cappuccio, Francesco Paolo; de Lorgeril, Michel; Dirckx, Carla; Donati, Maria Benedetta; Krogh, Vittorio; Siani, Alfonso; van Dongen, Marten C J M; Zito, Francesco; de Gaetano, Giovanni; Iacoviello, Licia

    2007-09-01

    Shared environmental factors may confer to spouses a similar risk for cardiovascular disease. We aimed at investigating in pairs the concordance in risk factors for cardiovascular disease and in global risk of cardiovascular events. In the framework of the IMMIDIET Project, married couples, recruited randomly from general practice, were studied. One thousand six hundred and four apparently healthy subjects aged 25-74 years from three different European populations were enrolled. Individual cardiovascular risks were estimated using SCORE risk equations. Age was strongly correlated within couples (r = 0.86, P < 0.0001). In multivariate model, within-pair correlation was high for social status (r = 0.49; percentage of explained variation = 24%) and percent of calories from lipids (r = 0.34; 12%). Concerning conventional metabolic risk factors, percentage of explained variation varied from 0.5% (triglycerides) to 11% (glucose). Among new risk factors, activated factor VII showed the strongest correlation (r = 0.28) and C-reactive protein the lowest (r = 0.13). Either total, coronary or non-coronary risk estimates at 10 years were strongly correlated within pairs: the risk of a member explained about two thirds of the cardiovascular risk of the partner. Spouse pairs share common lifestyle habits, common and new metabolic risk factors and the predicted global risk of cardiovascular events. If the individual risk of a person is influenced by the risk of his/her partner, decreasing the risk in a member of the pair should also decrease the risk in the partner. These concepts may have important public health consequences in targeting screening or disease prevention measures towards partners of people with cardiovascular risk.

  18. Global Co-Existence of Two Evolutionary Lineages of Parvovirus B19 1a, Different in Genome-Wide Synonymous Positions

    PubMed Central

    van Binnendijk, Rob S.; Boot, Hein J.; Zaaijer, Hans L.

    2012-01-01

    Parvovirus B19 (B19V) can cause infection in humans. To date, three genotypes of B19V, with subtypes, are known, of which genotype 1a is the most prevalent genotype in the Western world. We sequenced the genome of B19V strains of 65 asymptomatic, recently infected Dutch blood donors, to investigate the spatio-temporal distribution of B19V strains, in the years 2003–2009. The sequences were compared to B19V sequences from Dutch patients with fifth disease, and to global B19V sequences as available from GenBank. All Dutch B19V strains belonged to genotype 1a. Phylogenetic analysis of the strains from Dutch blood donors showed that two groups of genotype 1a co-exist. A clear-cut division into the two groups was also found among the B19V strains from Dutch patients, and among the B19V sequences in GenBank. The two groups of genotype 1a co-exist around the world and do not appear to differ in their ability to cause disease. Strikingly, the two groups of B19V predominantly differ in synonymous mutations, distributed throughout the entire genome of B19V. We propose to call the two groups of B19V genotype 1a respectively subtype 1a1 and 1a2. PMID:22912828

  19. Correcting acoustic Doppler current profiler discharge measurement bias from moving-bed conditions without global positioning during the 2004 Glen Canyon Dam controlled flood on the Colorado River

    USGS Publications Warehouse

    Gartner, J.W.; Ganju, N.K.

    2007-01-01

    Discharge measurements were made by acoustic Doppler current profiler at two locations on the Colorado River during the 2004 controlled flood from Glen Canyon Dam, Arizona. Measurement hardware and software have constantly improved from the 1980s such that discharge measurements by acoustic profiling instruments are now routinely made over a wide range of hydrologic conditions. However, measurements made with instruments deployed from moving boats require reliable boat velocity data for accurate measurements of discharge. This is normally accomplished by using special acoustic bottom track pings that sense instrument motion over bottom. While this method is suitable for most conditions, high current flows that produce downstream bed sediment movement create a condition known as moving bed that will bias velocities and discharge to lower than actual values. When this situation exists, one solution is to determine boat velocity with satellite positioning information. Another solution is to use a lower frequency instrument. Discharge measurements made during the 2004 Glen Canyon controlled flood were subject to moving-bed conditions and frequent loss of bottom track. Due to site conditions and equipment availability, the measurements were conducted without benefit of external positioning information or lower frequency instruments. This paper documents and evaluates several techniques used to correct the resulting underestimated discharge measurements. One technique produces discharge values in good agreement with estimates from numerical model and measured hydrographs during the flood. ?? 2007, by the American Society of Limnology and Oceanography, Inc.

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

    NASA Astrophysics Data System (ADS)

    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

  1. Mapping Global Citizenship

    ERIC Educational Resources Information Center

    Stein, Sharon

    2015-01-01

    The demand to cultivate global citizenship is frequently invoked as central to colleges' and universities' internationalization efforts. However, the term "global citizenship" remains undertheorized in the context of U.S. higher education. This article maps and engages three common global citizenship positions--entrepreneurial, liberal…

  2. Development and validation of a global positioning system-based "map book" system for categorizing cluster residency status of community members living in high-density urban slums in Blantyre, Malawi.

    PubMed

    MacPherson, Peter; Choko, Augustine T; Webb, Emily L; Thindwa, Deus; Squire, S Bertel; Sambakunsi, Rodrick; van Oosterhout, Joep J; Chunda, Treza; Chavula, Kondwani; Makombe, Simon D; Lalloo, David G; Corbett, Elizabeth L

    2013-05-15

    A significant methodological challenge in implementing community-based cluster-randomized trials is how to accurately categorize cluster residency when data are collected at a site distant from households. This study set out to validate a map book system for use in urban slums with no municipal address systems, where classification has been shown to be inaccurate when address descriptions were used. Between April and July 2011, 28 noncontiguous clusters were demarcated in Blantyre, Malawi. In December 2011, antiretroviral therapy initiators were asked to identify themselves as cluster residents (yes/no and which cluster) by using map books. A random sample of antiretroviral therapy initiators was used to validate map book categorization against Global Positioning System coordinates taken from participants' households. Of the 202 antiretroviral therapy initiators, 48 (23.8%) were categorized with the map book system as in-cluster residents and 147 (72.8%) as out-of-cluster residents, and 7 (3.4%) were unsure. Agreement between map books and the Global Positioning System was 100% in the 20 adults selected for validation and was 95.0% (κ = 0.96, 95% confidence interval: 0.84, 1.00) in an additional 20 in-cluster residents (overall κ = 0.97, 95% confidence interval: 0.90, 1.00). With map books, cluster residents were classified rapidly and accurately. If validated elsewhere, this approach could be of widespread value in that it would enable accurate categorization without home visits.

  3. Record of the Late Devonian Hangenberg global positive carbon-isotope excursion in an epeiric sea setting: Carbonate production, organic-carbon burial and paleoceanography during the late Famennian

    USGS Publications Warehouse

    Cramer, Bradley D.; Saltzman, Matthew R.; Day, J.E.; Witzke, B.J.

    2008-01-01

    Latest Famennian marine carbonates from the mid-continent of North America were examined to investigate the Late Devonian (very late Famennian) Hangenberg positive carbon-isotope (??13 Ccarb) excursion. This global shift in the ?? 13C of marine waters began during the late Famennian Hangenberg Extinction Event that occurred during the Middle Siphonodella praesulcata conodont zone. The post-extinction recovery interval spans the Upper S. praesulcata Zone immediately below the Devonian-Carboniferous boundary. Positive excursions in ?? 13 Ccarb are often attributed to the widespread deposition of organic-rich black shales in epeiric sea settings. The Hangenberg ??13 Ccarb excursion documented in the Louisiana Limestone in this study shows the opposite trend, with peak ??13 Ccarb values corresponding to carbonate production in the U.S. mid-continent during the highstand phase of the very late Famennian post-glacial sea level rise. Our data indicate that the interval of widespread black shale deposition (Hangenberg Black Shale) predates the peak isotope values of the Hangenberg ??13 Ccarb excursion and that peak values of the Hangenberg excursion in Missouri are not coincident with and cannot be accounted for by high Corg burial in epeiric seas. We suggest instead that sequestration and burial of Corg in the deep oceans drove the peak interval of the ??13Ccarb excursion, as a result of a change in the site of deep water formation to low-latitude epeiric seas as the global climate shifted between cold and warm states.

  4. Heterogeneity of myotubes generated by the MyoD and E12 basic helix-loop-helix transcription factors in otherwise non-differentiation growth conditions.

    PubMed

    Grubišić, Vladimir; Gottipati, Manoj K; Stout, Randy F; Grammer, J Robert; Parpura, Vladimir

    2014-02-01

    We used a synthetic biology approach to produce myotubes from mammalian C2C12 myoblasts in non-differentiation growth conditions using the expression of basic helix-loop-helix transcription factors, MyoD and E12, in various combinations and configurations. Our approach not only recapitulated the basics of muscle development and physiology, as the obtained myotubes showed qualities similar to those seen in striated muscle fibers in vivo, but also allowed for the synthesis of populations of myotubes which assumed distinct morphology, myofibrillar development and Ca(2+) dynamics. This fashioned class of biomaterials is suitable for the building blocks of soft actuators in micro-scale biomimetic robotics. This production line strategy can be embraced in reparative medicine as synthetic human myotubes with predetermined morphological/functional properties could be obtained using this very approach. This methodology can be adopted beyond striated muscle for the engineering of other tissue components/cells whose differentiation is governed by the principles of basic helix-loop-helix transcription factors, as in the case, for example, of neural or immune cell types.

  5. Global Positioning System Data-Loggers: A Tool to Quantify Fine-Scale Movement of Domestic Animals to Evaluate Potential for Zoonotic Transmission to an Endangered Wildlife Population

    PubMed Central

    Parsons, Michele B.; Gillespie, Thomas R.; Lonsdorf, Elizabeth V.; Travis, Dominic; Lipende, Iddi; Gilagiza, Baraka; Kamenya, Shadrack; Pintea, Lilian; Vazquez-Prokopec, Gonzalo M.

    2014-01-01

    Domesticated animals are an important source of pathogens to endangered wildlife populations, especially when anthropogenic activities increase their overlap with humans and wildlife. Recent work in Tanzania reports the introduction of Cryptosporidium into wild chimpanzee populations and the increased risk of ape mortality associated with SIVcpz-Cryptosporidium co-infection. Here we describe the application of novel GPS technology to track the mobility of domesticated animals (27 goats, 2 sheep and 8 dogs) with the goal of identifying potential routes for Cryptosporidium introduction into Gombe National Park. Only goats (5/27) and sheep (2/2) were positive for Cryptosporidium. Analysis of GPS tracks indicated that a crop field frequented by both chimpanzees and domesticated animals was a potential hotspot for Cryptosporidium transmission. This study demonstrates the applicability of GPS data-loggers in studies of fine-scale mobility of animals and suggests that domesticated animal–wildlife overlap should be considered beyond protected boundaries for long-term conservation strategies. PMID:25365070

  6. Global positioning system data-loggers: a tool to quantify fine-scale movement of domestic animals to evaluate potential for zoonotic transmission to an endangered wildlife population.

    PubMed

    Parsons, Michele B; Gillespie, Thomas R; Lonsdorf, Elizabeth V; Travis, Dominic; Lipende, Iddi; Gilagiza, Baraka; Kamenya, Shadrack; Pintea, Lilian; Vazquez-Prokopec, Gonzalo M

    2014-01-01

    Domesticated animals are an important source of pathogens to endangered wildlife populations, especially when anthropogenic activities increase their overlap with humans and wildlife. Recent work in Tanzania reports the introduction of Cryptosporidium into wild chimpanzee populations and the increased risk of ape mortality associated with SIVcpz-Cryptosporidium co-infection. Here we describe the application of novel GPS technology to track the mobility of domesticated animals (27 goats, 2 sheep and 8 dogs) with the goal of identifying potential routes for Cryptosporidium introduction into Gombe National Park. Only goats (5/27) and sheep (2/2) were positive for Cryptosporidium. Analysis of GPS tracks indicated that a crop field frequented by both chimpanzees and domesticated animals was a potential hotspot for Cryptosporidium transmission. This study demonstrates the applicability of GPS data-loggers in studies of fine-scale mobility of animals and suggests that domesticated animal-wildlife overlap should be considered beyond protected boundaries for long-term conservation strategies.

  7. Repression of global protein synthesis by Eif1a-like genes that are expressed specifically in the two-cell embryos and the transient Zscan4-positive state of embryonic stem cells.

    PubMed

    Hung, Sandy S C; Wong, Raymond C B; Sharov, Alexei A; Nakatake, Yuhki; Yu, Hong; Ko, Minoru S H

    2013-08-01

    Mouse embryonic stem (ES) cells are prototypical stem cells that remain undifferentiated in culture for long periods, yet maintain the ability to differentiate into essentially all cell types. Previously, we have reported that ES cells oscillate between two distinct states, which can be distinguished by the transient expression of Zscan4 genes originally identified for its specific expression in mouse two-cell stage embryos. Here, we report that the nascent protein synthesis is globally repressed in the Zscan4-positive state of ES cells, which is mediated by the transient expression of newly identified eukaryotic translation initiation factor 1A (Eif1a)-like genes. Eif1a-like genes, clustered on Chromosome 12, show the high sequence similarity to the Eifa1 and consist of 10 genes (Eif1al1-Eif1al10) and 9 pseudogenes (Eif1al-ps1-Eif1al-ps9). The analysis of the expressed sequence tag database showed that Eif1a-like genes are expressed mostly in the two-cell stage mouse embryos. Microarray analyses and quantitative real-time polymerase chain reaction analyses show that Eif1a-like genes are expressed specifically in the Zscan4-positive state of ES cells. These results indicate a novel mechanism to repress protein synthesis by Eif1a-like genes and a unique mode of protein synthesis regulation in ES cells, which undergo a transient and reversible repression of global protein synthesis in the Zscan4-positive state.

  8. Globalization and human cooperation.

    PubMed

    Buchan, Nancy R; Grimalda, Gianluca; Wilson, Rick; Brewer, Marilynn; Fatas, Enrique; Foddy, Margaret

    2009-03-17

    Globalization magnifies the problems that affect all people and that require large-scale human cooperation, for example, the overharvesting of natural resources and human-induced global warming. However, what does globalization imply for the cooperation needed to address such global social dilemmas? Two competing hypotheses are offered. One hypothesis is that globalization prompts reactionary movements that reinforce parochial distinctions among people. Large-scale cooperation then focuses on favoring one's own ethnic, racial, or language group. The alternative hypothesis suggests that globalization strengthens cosmopolitan attitudes by weakening the relevance of ethnicity, locality, or nationhood as sources of identification. In essence, globalization, the increasing interconnectedness of people worldwide, broadens the group boundaries within which individuals perceive they belong. We test these hypotheses by measuring globalization at both the country and individual levels and analyzing the relationship between globalization and individual cooperation with distal others in multilevel sequential cooperation experiments in which players can contribute to individual, local, and/or global accounts. Our samples were drawn from the general populations of the United States, Italy, Russia, Argentina, South Africa, and Iran. We find that as country and individual levels of globalization increase, so too does individual cooperation at the global level vis-à-vis the local level. In essence, "globalized" individuals draw broader group boundaries than others, eschewing parochial motivations in favor of cosmopolitan ones. Globalization may thus be fundamental in shaping contemporary large-scale cooperation and may be a positive force toward the provision of global public goods. PMID:19255433

  9. Globalization and human cooperation.

    PubMed

    Buchan, Nancy R; Grimalda, Gianluca; Wilson, Rick; Brewer, Marilynn; Fatas, Enrique; Foddy, Margaret

    2009-03-17

    Globalization magnifies the problems that affect all people and that require large-scale human cooperation, for example, the overharvesting of natural resources and human-induced global warming. However, what does globalization imply for the cooperation needed to address such global social dilemmas? Two competing hypotheses are offered. One hypothesis is that globalization prompts reactionary movements that reinforce parochial distinctions among people. Large-scale cooperation then focuses on favoring one's own ethnic, racial, or language group. The alternative hypothesis suggests that globalization strengthens cosmopolitan attitudes by weakening the relevance of ethnicity, locality, or nationhood as sources of identification. In essence, globalization, the increasing interconnectedness of people worldwide, broadens the group boundaries within which individuals perceive they belong. We test these hypotheses by measuring globalization at both the country and individual levels and analyzing the relationship between globalization and individual cooperation with distal others in multilevel sequential cooperation experiments in which players can contribute to individual, local, and/or global accounts. Our samples were drawn from the general populations of the United States, Italy, Russia, Argentina, South Africa, and Iran. We find that as country and individual levels of globalization increase, so too does individual cooperation at the global level vis-à-vis the local level. In essence, "globalized" individuals draw broader group boundaries than others, eschewing parochial motivations in favor of cosmopolitan ones. Globalization may thus be fundamental in shaping contemporary large-scale cooperation and may be a positive force toward the provision of global public goods.

  10. Measurement of ridge-spreading movements (Sackungen) at Bald Eagle Mountain, Lake County, Colorado, II : continuation of the 1975-1989 measurements using a Global Positioning System in 1997 and 1999

    USGS Publications Warehouse

    Varnes, David J.; Coe, J.A.; Godt, J.W.; Savage, W.Z.; Savage, J.E.

    2000-01-01

    Measurements of ridge-spreading movements at Bald Eagle Mountain in north-central Colorado were reported in USGS Open-File Report 90-543 for the years 1975-1989. Measurements were renewed in 1997 and 1999 using the Global Positioning System (GPS). Movements are generally away from a ridge-top graben and appear to be concentrated along 3 or 4 trenches with uphill facing scarps that are parallel with slope contours. A point just below the lowest trench has moved the most? a total of 8.3 cm horizontally and slightly downward from 1977 to 1999 relative to an assumed stable point on the periphery of the graben. Movements from 1997 to 1999 are less than 1 cm or within the error of measurement.

  11. High sensitivity cavity ring down spectroscopy of N2O near 1.22 μm: (II) 14N216O line intensity modeling and global fit of 14N218O line positions

    NASA Astrophysics Data System (ADS)

    Tashkun, S. A.; Perevalov, V. I.; Karlovets, E. V.; Kassi, S.; Campargue, A.

    2016-06-01

    In a recent work (Karlovets et al., 2016 [1]), we reported the measurement and rovibrational assignments of more than 3300 transitions belonging to 64 bands of five nitrous oxide isotopologues (14N216O, 14N15N16O, 15N14N16O, 14N218O and 14N217O) in the high sensitivity CRDS spectrum recorded in the 7915-8334 cm-1 spectral range. The assignments were performed by comparison with predictions of the effective Hamiltonian models developed for each isotopologue. In the present paper, the large amount of measurements from our previous work mentioned above and literature are gathered to refine the modeling of the nitrous oxide spectrum in two ways: (i) improvement of the intensity modeling for the principal isotopologue, 14N216O, near 8000 cm-1 from a new fit of the relevant effective dipole moment parameters, (ii) global modeling of 14N218O line positions from a new fit of the parameters of the global effective Hamiltonian using an exhaustive input dataset collected in the literature in the 12-8231 cm-1 region. The fitted set of 81 parameters allowed reproducing near 5800 measured line positions with an RMS deviation of 0.0016 cm-1. The dimensionless weighted standard deviation of the fit is 1.22. As an illustration of the improvement of the predictive capabilities of the obtained effective Hamiltonian, two new 14N218O bands could be assigned in the CRDS spectrum in the 7915-8334 cm-1 spectral range. A line list at 296 K has been generated in the 0-10,700 cm-1 range for 14N218O in natural abundance with a 10-30 cm/molecule intensity cutoff.

  12. Teaching Motion with the Global Positioning System

    ERIC Educational Resources Information Center

    Budisa, Marko; Planinsic, Gorazd

    2003-01-01

    We have used the GPS receiver and a PC interface to track different types of motion. Various hands-on experiments that enlighten the physics of motion at the secondary school level are suggested (visualization of 2D and 3D motion, measuring car drag coefficient and fuel consumption). (Contains 8 figures.)

  13. Integrated Global Positioning Systems (GPS) Laboratory

    NASA Technical Reports Server (NTRS)

    Brown, Dewayne Randolph

    2002-01-01

    The purpose of this research is to develop a user-friendly Integrated GPS lab manual. This manual will help range engineers at NASA to integrate the use of GPS Simulators, GPS receivers, computers, MATLAB software, FUGAWI software and SATELLITE TOOL KIT software. The lab manual will be used in an effort to help NASA engineers predict GPS Coverage of planned operations and analyze GPS coverage of operation post mission. The Integrated GPS Laboratory was used to do GPS Coverage for two extensive case studies. The first scenario was an airplane trajectory in which an aircraft flew from Cape Canaveral to Los Angeles, California. In the second scenario, a rocket trajectory was done whereas a rocket was launched from Cape Canaveral to one thousand kilometers due east in the Atlantic Ocean.

  14. The LANDSAT/global positioning system project

    NASA Technical Reports Server (NTRS)

    Wood, Terri

    1988-01-01

    A GPSPAC/LANDSAT-D Interface (GLI) Ground Support System was built to validate the performance and to calibrate the accuracy of the experimental navigation package, GPSPAC, flown on the LANDSAT-4 and 5 spacecraft. Although the GLI system operated successfully to give the orbit information needed to validate the GPSPAC, it also detected two anomalies: one is characteristic of the GLI system and the other is characteristic of the pre-operational phase of GPS. Several methods were applied to resolve or reduce the anomalies. This paper presents a description of the problems, the methods applied to resolve or reduce them, and the results.

  15. Preparing Global Citizens

    ERIC Educational Resources Information Center

    Roberts, Dennis C.; Welch, Lucas; Al-Khanji, Khalid

    2013-01-01

    Global citizens are those who are aware of, demonstrate respect for, and are comfortable engaging across cultural boundaries. This article explores why preparing global citizens is important and how positive psychology can inform our understanding of those who engage comfortably in today's complicated world. Soliya's Connect program is described…

  16. Global Fluency.

    ERIC Educational Resources Information Center

    Tosti, Donald T.

    1999-01-01

    Defines global fluency as a facility with cultural behaviors that help an organization thrive in an ever-changing global business environment; and discusses business culture, global culture, an example of a change effort at a global company, leadership values, company values, and defining global values and practices. (Author/LRW)

  17. Nursing Positions

    MedlinePlus

    ... Story" 5 Things to Know About Zika & Pregnancy Nursing Positions KidsHealth > For Parents > Nursing Positions Print A ... and actually needs to feed. Getting Comfortable With Breastfeeding Nursing can be one of the most challenging ...

  18. Positive Psychology

    ERIC Educational Resources Information Center

    Peterson, Christopher

    2009-01-01

    Positive psychology is a deliberate correction to the focus of psychology on problems. Positive psychology does not deny the difficulties that people may experience but does suggest that sole attention to disorder leads to an incomplete view of the human condition. Positive psychologists concern themselves with four major topics: (1) positive…

  19. Positional plagiocephaly

    PubMed Central

    Cummings, Carl

    2011-01-01

    Cranial asymmetry occurring as a result of forces that deform skull shape in the supine position is known as deformational plagiocephaly. The risk of plagiocephaly may be modified by positioning the baby on alternate days with the head to the right or the left side, and by increasing time spent in the prone position during awake periods. When deformational plagiocephaly is already present, physiotherapy (including positioning equivalent to the preventive positioning, and exercises as needed for torticollis and positional preference) has been shown to be superior to counselling about preventive positioning only. Helmet therapy (moulding therapy) to reduce skull asymmetry has some drawbacks: it is expensive, significantly inconvenient due to the long hours of use per day and associated with skin complications. There is evidence that helmet therapy may increase the initial rate of improvement of asymmetry, but there is no evidence that it improves the final outcome for patients with moderate or severe plagiocephaly. PMID:23024590

  20. Satellite positioning

    NASA Technical Reports Server (NTRS)

    Colombo, Oscar L.; Watkins, Michael M.

    1991-01-01

    Developments in satellite positioning techniques and their applications are reviewed on the basis of the theoretical and practical work published by U.S. researchers in 1987-1990. Current techniques are classified into two main categories: satellite laser tracking and radio tracking. Particular attention is given to the Geoscience Laser Ranging System, the Lunar Laser Ranging concept; GPS ephemerides determination, fiducial networks, and reference frame; static GPS positioning; and kinematic GPS positioning.

  1. One-dimensional global search: Nature-inspired vs. Lipschitz methods

    NASA Astrophysics Data System (ADS)

    Kvasov, Dmitri E.; Mukhametzhanov, Marat S.

    2016-06-01

    Lipschitz global optimization appears in many practical problems: decision making, optimal control, stability problems, finding the minimal root problems, etc. In many engineering applications the objective function is a "black-box", multiextremal, non-differentiable and hard to evaluate. Another common property of the function to be optimized very often is the Lipschitz condition. In this talk, the Lipschitz global optimization problem is considered and several nature-inspired and Lipschitz global optimization algorithms are briefly described and compared with respect to the number of evaluations of the objective function.

  2. Positive Psychotherapy

    ERIC Educational Resources Information Center

    Seligman, Martin E. P.; Rashid, Tayyab; Parks, Acacia C.

    2006-01-01

    Positive psychotherapy (PPT) contrasts with standard interventions for depression by increasing positive emotion, engagement, and meaning rather than directly targeting depressive symptoms. The authors have tested the effects of these interventions in a variety of settings. In informal student and clinical settings, people not uncommonly reported…

  3. Constraining the slip distribution and fault geometry of the Mw 7.9, 3 November 2002, Denali fault earthquake with Interferometric Synthetic Aperture Radar and Global Positioning System data

    USGS Publications Warehouse

    Wright, Tim J.; Lu, Zhiming; Wicks, C.

    2004-01-01

    The Mw 7.9, Denali fault earthquake (DFE) is the largest continental strike-slip earthquake to occur since the development of Interferometric Synthetic Aperture Radar (InSAR). We use five interferograms, constructed using radar images from the Canadian Radarsat-1 satellite, to map the surface deformation at the western end of the fault rupture. Additional geodetic data are provided by displacements observed at 40 campaign and continuous Global Positioning System (GPS) sites. We use the data to determine the geometry of the Susitna Glacier fault, thrusting on which initiated the DFE, and to determine a slip model for the entire event that is consistent with both the InSAR and GPS data. We find there was an average of 7.3 ± 0.4 m slip on the Susitna Glacier fault, between 1 and 9.5 km depth on a 29 km long fault that dips north at 41 ± 0.7° and has a surface projection close to the mapped rupture. On the Denali fault, a simple model with large slip patches finds a maximum of 8.7 ± 0.7 m of slip between the surface and 14.3 ± 0.2 km depth. A more complex distributed slip model finds a peak of 12.5 ± 0.8 m in the upper 4 km, significantly higher than the observed surface slip. We estimate a geodetic moment of 670 ± 10 × 1018 N m (Mw 7.9), consistent with seismic estimates. Lack of preseismic data resulted in an absence of InSAR coverage for the eastern half of the DFE rupture. A dedicated geodetic InSAR mission could obviate coverage problems in the future.

  4. Feasibility and Acceptability of Global Positioning System (GPS) Methods to Study the Spatial Contexts of Substance Use and Sexual Risk Behaviors among Young Men Who Have Sex with Men in New York City: A P18 Cohort Sub-Study

    PubMed Central

    Duncan, Dustin T.; Kapadia, Farzana; Regan, Seann D.; Goedel, William C.; Levy, Michael D.; Barton, Staci C.; Friedman, Samuel R.; Halkitis, Perry N.

    2016-01-01

    Background No global positioning system (GPS) technology study has been conducted among a sample of young gay, bisexual, and other men who have sex with men (YMSM). As such, the purpose of this study was to evaluate the feasibility and acceptability of using GPS methods to understand the spatial context of substance use and sexual risk behaviors among a sample of YMSM in New York City, a high-risk population. Methods Data came from a subsample of the ongoing P18 Cohort Study (n = 75). GPS feasibility and acceptability among participants was measured with: 1) a pre- and post-survey and 2) adherence to the GPS protocol which included returning the GPS device, self-report of charging and carrying the GPS device as well as objective data analyzed from the GPS devices. Analyses of the feasibility surveys were treated as repeated measures as each participant had a pre- and post-feasibility survey. When comparing the similar GPS survey items asked at baseline and at follow-up, we present percentages and associated p-values based on chi-square statistics. Results Participants reported high ratings of pre-GPS acceptability, ease of use, and low levels of wear-related concerns in addition to few concerns related to safety, loss, or appearance, which were maintained after baseline GPS feasibility data collection. The GPS return rate was 100%. Most participants charged and carried the GPS device on most days. Of the total of 75 participants with GPS data, 75 (100%) have at least one hour of GPS data for one day and 63 (84%) had at least one hour on all 7 days. Conclusions Results from this pilot study demonstrate that utilizing GPS methods among YMSM is feasible and acceptable. GPS devices may be used in spatial epidemiology research in YMSM populations to understand place-based determinants of health such as substance use and sexual risk behaviors. PMID:26918766

  5. Positioning Agility

    NASA Astrophysics Data System (ADS)

    Oza, Nilay; Abrahamsson, Pekka; Conboy, Kieran

    Agile methods are increasingly adopted by European companies. Academics too are conducting numerous studies on different tenets of agile methods. Companies often feel proud in marketing themselves as ‘agile’. However, the true notion of ‘being agile’ seems to have been overlooked due to lack of positioning of oneself for agility. This raises a call for more research and interactions between academia and the industry. The proposed workshop refers to this call. It will be highly relevant to participants, interested in positioning their company’s agility from organizational, group or project perspectives. The positioning of agility will help companies to better align their agile practices with stakeholder values. Results of the workshop will be shared across participants and they will also have opportunity to continue their work on agile positioning in their companies. At broader level, the work done in this workshop will contribute towards developing Agile Positioning System.

  6. Global Initiatives for Early Childhood Care and Education: Global Guidelines and Global Guidelines Assessment

    ERIC Educational Resources Information Center

    Trube, Mary Barbara

    2015-01-01

    This report focuses on the Association for Childhood Education International's (ACEI) Global Guidelines (GG) and Global Guidelines Assessment (GGA), which were developed in response to and in keeping with the prominence that the issue of quality early childhood care, development, and education has reached globally. Further, the paper positions the…

  7. Global solidarity, migration and global health inequity.

    PubMed

    Eckenwiler, Lisa; Straehle, Christine; Chung, Ryoa

    2012-09-01

    The grounds for global solidarity have been theorized and conceptualized in recent years, and many have argued that we need a global concept of solidarity. But the question remains: what can motivate efforts of the international community and nation-states? Our focus is the grounding of solidarity with respect to global inequities in health. We explore what considerations could motivate acts of global solidarity in the specific context of health migration, and sketch briefly what form this kind of solidarity could take. First, we argue that the only plausible conceptualization of persons highlights their interdependence. We draw upon a conception of persons as 'ecological subjects' and from there illustrate what such a conception implies with the example of nurses migrating from low and middle-income countries to more affluent ones. Next, we address potential critics who might counter any such understanding of current international politics with a reference to real-politik and the insights of realist international political theory. We argue that national governments--while not always or even often motivated by moral reasons alone--may nevertheless be motivated to acts of global solidarity by prudential arguments. Solidarity then need not be, as many argue, a function of charitable inclination, or emergent from an acknowledgment of injustice suffered, but may in fact serve national and transnational interests. We conclude on a positive note: global solidarity may be conceptualized to helpfully address global health inequity, to the extent that personal and transnational interdependence are enough to motivate national governments into action.

  8. Positive Proof.

    ERIC Educational Resources Information Center

    Auty, Geoffrey

    1988-01-01

    Presents experiments which show that in electrostatics there are logical reasons for describing charged materials as positive or negative. Indicates that static and current electricity are not separate areas of physics. Diagrams of experiments and circuits are included. (RT)

  9. Positioning Fixture For Survey Antenna

    NASA Technical Reports Server (NTRS)

    Dinardo, Steven J.; Smith, Mark A.

    1994-01-01

    Improved positioning fixture designed to simplify and accelerate accurate alignment of antenna for use in land survey aided by satellites of Global Positioning System. Holds antenna at fixed height and orientation over station monument so survey measurements made with accuracy and precision.

  10. Position indicator

    DOEpatents

    Tanner, David E.

    1981-01-01

    A nuclear reactor system is described in which a position indicator is provided for detecting and indicating the position of a movable element inside a pressure vessel. The movable element may be a valve element or similar device which moves about an axis. Light from a light source is transmitted from a source outside the pressure vessel to a first region inside the pressure vessel in alignment with the axis of the movable element. The light is redirected by a reflector prism to a second region displaced radially from the first region. The reflector prism moves in response to movement of the movable element about its axis such that the second region moves arcuately with respect to the first region. Sensors are arrayed in an arc corresponding to the arc of movement of the second region and signals are transmitted from the sensors to the exterior of the reactor vessel to provide indication of the position of the movable element.

  11. Global HRD.

    ERIC Educational Resources Information Center

    1997

    This document contains four papers from a symposium on global human resource development (HRD). "Globalization of Human Resource Management (HRM) in Government: A Cross-Cultural Perspective" (Pan Suk Kim) relates HRM to national cultures and addresses its specific functional aspects with a unique dimension in a global organization. "An…

  12. Global Education.

    ERIC Educational Resources Information Center

    Berkley, June, Ed.

    1982-01-01

    The articles in this collection deal with various methods of global education--education to prepare students to function as understanding and informed citizens of the world. Topics discussed in the 26 articles include: (1) the necessity of global education; (2) global education in the elementary school language arts curriculum; (3) science fiction…

  13. Global Education.

    ERIC Educational Resources Information Center

    Longstreet, Wilma S., Ed.

    1988-01-01

    This issue contains an introduction ("The Promise and Perplexity of Globalism," by W. Longstreet) and seven articles dedicated to exploring the meaning of global education for today's schools. "Global Education: An Overview" (J. Becker) develops possible definitions, identifies objectives and skills, and addresses questions and issues in this…

  14. Positive psychotherapy.

    PubMed

    Seligman, Martin E P; Rashid, Tayyab; Parks, Acacia C

    2006-11-01

    Positive psychotherapy (PPT) contrasts with standard interventions for depression by increasing positive emotion, engagement, and meaning rather than directly targeting depressive symptoms. The authors have tested the effects of these interventions in a variety of settings. In informal student and clinical settings, people not uncommonly reported them to be "life-changing." Delivered on the Web, positive psychology exercises relieved depressive symptoms for at least 6 months compared with placebo interventions, the effects of which lasted less than a week. In severe depression, the effects of these Web exercises were particularly striking. This address reports two preliminary studies: In the first, PPT delivered to groups significantly decreased levels of mild-to-moderate depression through 1-year follow-up. In the second, PPT delivered to individuals produced higher remission rates than did treatment as usual and treatment as usual plus medication among outpatients with major depressive disorder. Together, these studies suggest that treatments for depression may usefully be supplemented by exercises that explicitly increase positive emotion, engagement, and meaning. ((c) 2006 APA, all rights reserved). PMID:17115810

  15. Positively Adolescent!

    ERIC Educational Resources Information Center

    Williamson, Sue

    2000-01-01

    Believes that music teachers should reassess their views toward adolescent behavior in the music classroom by learning to see their behavior in a positive light. Describes teaching strategies that build on four adolescent behaviors: (1) desire for peer acceptance; (2) abundant energy; (3) love of fun; and (4) limited time-managing skills. (CMK)

  16. Taking a Position

    NASA Technical Reports Server (NTRS)

    1999-01-01

    "TerrAvoid" and "Position Integrity" combine Global Positioning Satellite (GPS) data with high-resolution maps of the Earth's topography. Dubbs & Severino, Inc., based in Irvine, California, has developed software that allows the system to be run on a battery-powered laptop in the cockpit. The packages, designed primarily for military sponsors and now positioned to hit the consumer market in coming months, came about as the result of the Jet Propulsion Laboratory's Technology Affiliates Program. Intended to give American industry assistance from NASA experts and to facilitate business use of intellectual property developed for the space program, the Technology Affiliates Program introduced the start-up company of Dubbs & Severino to JPL's Dr. Nevin Bryant four years ago. GeoTIFF is now in the public domain, and its use for commercial product development has evolved into an industry standard over the last year.

  17. Position sensor

    NASA Technical Reports Server (NTRS)

    Auer, Siegfried (Inventor)

    1988-01-01

    A radiant energy angle sensor is provided wherein the sensitive portion thereof comprises a pair of linear array detectors with each detector mounted normal to the other to provide X and Y channels and a pair of slits spaced from the pair of linear arrays with each of the slits positioned normal to its associated linear array. There is also provided electrical circuit means connected to the pair of linear array detectors and to separate X and Y axes outputs.

  18. Positive Psychologists on Positive Constructs

    ERIC Educational Resources Information Center

    Lyubomirsky, Sonja

    2012-01-01

    Comments on the original article by McNulty and Fincham (see record 2011-15476-001). In their article, the authors offered compelling evidence that constructs such as forgiveness and optimism can have both beneficial and adverse consequences, depending on the context. Their caution about labeling particular psychological processes as "positive" is…

  19. Positioning apparatus

    DOEpatents

    Vogel, M.A.; Alter, P.

    1983-07-07

    An apparatus is provided for precisely adjusting the position of an article relative to a beam emerging from a neutron source disposed in a housing. The apparatus includes a support pivotably mounted on a movable base plate and freely suspended therefrom. The support is gravity biased toward the housing and carries an article holder movable in a first direction longitudinally of the axis of said beam and normally urged into engagement against said housing. Means are provided for moving the base plate in two directions to effect movement of the suspended holder in two mutually perpendicular directions, respectively, normal to the axis of the beam.

  20. Positioning apparatus

    DOEpatents

    Vogel, Max A.; Alter, Paul

    1986-05-06

    An apparatus for precisely positioning materials test specimens within the optimum neutron flux path emerging from a neutron source located in a housing. The test specimens are retained in a holder mounted on the free end of a support pivotably mounted and suspended from a movable base plate. The support is gravity biased to urge the holder in a direction longitudinally of the flux path against the housing. Means are provided for moving the base plate in two directions to effect movement of the holder in two mutually perpendicular directions normal to the axis of the flux path.

  1. Positioning apparatus

    DOEpatents

    Vogel, Max A.; Alter, Paul

    1986-01-01

    An apparatus for precisely positioning materials test specimens within the optimum neutron flux path emerging from a neutron source located in a housing. The test specimens are retained in a holder mounted on the free end of a support pivotably mounted and suspended from a movable base plate. The support is gravity biased to urge the holder in a direction longitudinally of the flux path against the housing. Means are provided for moving the base plate in two directions to effect movement of the holder in two mutually perpendicular directions normal to the axis of the flux path.

  2. POSITIONING DEVICE

    DOEpatents

    Wall, R.R.; Peterson, D.L.

    1959-09-15

    A positioner is described for a vertical reactor-control rod. The positioner comprises four grooved friction rotatable members that engage the control rod on all sides and shift it longitudinally. The four friction members are drivingly interconnected for conjoint rotation and comprise two pairs of coaxial members. The members of each pair are urged toward one another by hydraulic or pneumatic pressure and thus grip the control rod so as to hold it in any position or adjust it. Release of the by-draulic or pneumatic pressure permits springs between the friction members of each pair to force them apart, whereby the control rod moves quickly by gravity into the reactor.

  3. The Global Circuit.

    ERIC Educational Resources Information Center

    Lansford, Henry

    1983-01-01

    Discusses the nature of and research related to a theory explaining the earth's electric budget. The theory suggests a global electric circuit completed by a positive current flowing up into thunderstorm clouds, from clouds to ionosphere, distributed around the globe, and down to earth through the lower atmosphere in fair-weather regions. (JN)

  4. Global solidarity, migration and global health inequity.

    PubMed

    Eckenwiler, Lisa; Straehle, Christine; Chung, Ryoa

    2012-09-01

    The grounds for global solidarity have been theorized and conceptualized in recent years, and many have argued that we need a global concept of solidarity. But the question remains: what can motivate efforts of the international community and nation-states? Our focus is the grounding of solidarity with respect to global inequities in health. We explore what considerations could motivate acts of global solidarity in the specific context of health migration, and sketch briefly what form this kind of solidarity could take. First, we argue that the only plausible conceptualization of persons highlights their interdependence. We draw upon a conception of persons as 'ecological subjects' and from there illustrate what such a conception implies with the example of nurses migrating from low and middle-income countries to more affluent ones. Next, we address potential critics who might counter any such understanding of current international politics with a reference to real-politik and the insights of realist international political theory. We argue that national governments--while not always or even often motivated by moral reasons alone--may nevertheless be motivated to acts of global solidarity by prudential arguments. Solidarity then need not be, as many argue, a function of charitable inclination, or emergent from an acknowledgment of injustice suffered, but may in fact serve national and transnational interests. We conclude on a positive note: global solidarity may be conceptualized to helpfully address global health inequity, to the extent that personal and transnational interdependence are enough to motivate national governments into action. PMID:22827320

  5. Global Tropospheric OH

    NASA Astrophysics Data System (ADS)

    Nicely, J. M.; Canty, T. P.; Lang, C.; Duncan, B. N.; Liang, Q.; Oman, L.; Salawitch, R. J.; Stolarski, R. S.; Waugh, D. W.

    2012-12-01

    The oxidizing capacity of the troposphere is controlled, to a large extent, by the abundance of hydroxyl radical (OH). The global mean concentration of OH, inferred from measurements of methyl chloroform, has remained relatively constant during the past several decades, despite rising levels of CH4 that should have led to a steady decline. Here we examine other factors that may have affected global [OH], such as the overhead burden of stratospheric O3 and tropospheric H2O, using global OH fields from the GEOS Chemistry-Climate Model. Our analysis suggests these factors may have contributed a positive trend to global [OH] large enough to counter the decrease due to CH4.

  6. Local positioning system

    SciTech Connect

    Kyker, R.

    1995-07-25

    Navigation systems have been vital to transportation ever since man took to the air and sea. Early navigation systems utilized the sextant to navigate by starlight as well as the magnetic needle compass. As electronics and communication technologies improved, inertial navigation systems were developed for use in ships and missile delivery. These systems consisted of electronic compasses, gyro-compasses, accelerometers, and various other sensors. Recently, systems such as LORAN and the Global Positioning System (GPS) have utilized the properties of radio wave propagation to triangulate position. The Local Positioning System (LPS), described in this paper, is an implementation of a limited inertial navigation system designed to be used on a bicycle. LPS displays a cyclist`s current position relative to a starting location. This information is displayed in Cartesian-like coordinates. To accomplish this, LPS relies upon two sensors, an electronic compass sensor and a distance sensor. The compass sensor provides directional information while the distance sensor provides the distance traveled. This information yields a distance vector for each point in time which when summed produces the cyclist`s current position. LPS is microprocessor controlled and is designed for a range of less than 90 miles.

  7. Global Composite

    Atmospheric Science Data Center

    2013-04-19

    article title:  MISR Global Images See the Light of Day     View Larger Image ... than its nadir counterpart due to enhanced reflection of light by atmospheric particulates. MISR data are processed at the ...

  8. Global Albedo

    Atmospheric Science Data Center

    2013-04-19

    ... estimation of crop yields and disease outbreaks) and land management. Global MISR DHR maps are also available for all other parts of the ... of Directional Hemispherical Reflectance. project:  MISR category:  gallery date:  ...

  9. Global astrometry with OSI

    NASA Astrophysics Data System (ADS)

    Loiseau, Sacha; Malbet, Fabien; Yu, Jeffrey W.

    1995-06-01

    We present a method for performing global astrometry with the proposed Orbiting Stellar Interferometer. Because it is dedicated to wide-angle astrometry, OSI has the intrinsic capabilities to achieve global astrometry, even though it doesn't measure directly relative angles between pairs of stars, such as HIPPARCOS. In this paper, a time-independent model is shown, leading to a coherent solution for the positions of reference stars on the whole sky. With an initial measurement accuracy of 10 micro-arcseconds, corresponding to an accuracy of 340 picometers in the knowledge of the delay-line position of the observing interferometer, the consistent least-squares solution gives an accuracy by which the astrometric parameters can be obtained around 2 - 3 micro-arcseconds.

  10. American Universities in a Global Market

    ERIC Educational Resources Information Center

    Clotfelter, Charles T., Ed.

    2010-01-01

    In higher education, the United States is the preeminent global leader, dominating the list of the world's top research universities. But there are signs that America's position of global leadership will face challenges in the future, as it has in other realms of international competition. "American Universities in a Global Market"…

  11. Global Public Leadership in a Technological Era

    ERIC Educational Resources Information Center

    Masciulli, Joseph

    2011-01-01

    Good (ethical and effective) global public leadership--by national politicians, intergovernmental and nongovernmental international organizational leaders, multinational corporate leaders, and technoscientists--will make a significant positive difference in our global system's capacity to solve contemporary and futuristic global problems. High…

  12. Position, Navigation, and Timing: GPS Scientific Applications

    NASA Technical Reports Server (NTRS)

    Neilan, Ruth E.

    2008-01-01

    This slide presentation reviews the development and deployment of the Global Positioning System (GPS). This presentation also includes measuring space and time, GPS as a tool for science, development of high precision JPL GPS receivers, and technology and applications developments.

  13. Global Education.

    ERIC Educational Resources Information Center

    McCoubrey, Sharon

    1994-01-01

    This theme issue focuses on topics related to global issues. (1) "Recycling for Art Projects" (Wendy Stephenson) gives an argument for recycling in the art classroom; (2) "Winds of Change: Tradition and Innovation in Circumpolar Art" (Bill Zuk and Robert Dalton) includes profiles of Alaskan Yupik artist, Larry Beck, who creates art from recycled…

  14. Global Warming.

    ERIC Educational Resources Information Center

    Hileman, Bette

    1989-01-01

    States the foundations of the theory of global warming. Describes methodologies used to measure the changes in the atmosphere. Discusses steps currently being taken in the United States and the world to slow the warming trend. Recognizes many sources for the warming and the possible effects on the earth. (MVL)

  15. Global Warming?

    ERIC Educational Resources Information Center

    Eichman, Julia Christensen; Brown, Jeff A.

    1994-01-01

    Presents information and data on an experiment designed to test whether different atmosphere compositions are affected by light and temperature during both cooling and heating. Although flawed, the experiment should help students appreciate the difficulties that researchers face when trying to find evidence of global warming. (PR)

  16. Global Change

    USGS Publications Warehouse

    ,

    1993-01-01

    Global change is a relatively new area of scientific study using research from many disciplines to determine how Earth systems change, and to assess the influence of human activity on these changes. This teaching packet consists of a poster and three activity sheets. In teaching these activities four themes are important: time, change, cycles, and Earth as home.

  17. Panwapa: Global Kids, Global Connections

    ERIC Educational Resources Information Center

    Berson, Ilene R.; Berson, Michael J.

    2009-01-01

    Panwapa, created by the Sesame Street Workshop of PBS, is an example of an initiative on the Internet designed to enhance students' learning by exposing them to global communities. Panwapa means "Here on Earth" in Tshiluba, a Bantu language spoken in the Democratic Republic of Congo. At the Panwapa website, www.panwapa.org, children aged four to…

  18. Global Geodesy Using GPS Without Fiducial Sites

    NASA Technical Reports Server (NTRS)

    Heflin, Michael B.; Blewitt, Geoffrey

    1994-01-01

    Global Positioning System, GPS, used to make global geodetic measurements without use of fiducial site coordinates. Baseline lengths and geocentric radii for each site determined without having to fix any site coordinates. Given n globally distributed sites, n baseline lengths and n geocentric radii form polyhedron with each site at vertex and with geocenter at intersection of all radii. Geodetic information derived from structure of polyhedron and its change with time. Approach applied to any global geodetic technique.

  19. Going Global

    ERIC Educational Resources Information Center

    Boulard, Garry

    2010-01-01

    In a move to increase its out-of-state and international student enrollment, officials at the University of Iowa are stepping up their global recruitment efforts--even in the face of criticism that the school may be losing sight of its mission. The goal is to increase enrollment across the board, with both in-state as well as out-of-state and…

  20. Global Arrays

    2006-02-23

    The Global Arrays (GA) toolkit provides an efficient and portable “shared-memory” programming interface for distributed-memory computers. Each process in a MIMD parallel program can asynchronously access logical blocks of physically distributed dense multi-dimensional arrays, without need for explicit cooperation by other processes. Unlike other shared-memory environments, the GA model exposes to the programmer the non-uniform memory access (NUMA) characteristics of the high performance computers and acknowledges that access to a remote portion of the sharedmore » data is slower than to the local portion. The locality information for the shared data is available, and a direct access to the local portions of shared data is provided. Global Arrays have been designed to complement rather than substitute for the message-passing programming model. The programmer is free to use both the shared-memory and message-passing paradigms in the same program, and to take advantage of existing message-passing software libraries. Global Arrays are compatible with the Message Passing Interface (MPI).« less

  1. Positive maps, positive polynomials and entanglement witnesses

    NASA Astrophysics Data System (ADS)

    Skowronek, Łukasz; Życzkowski, Karol

    2009-08-01

    We link the study of positive quantum maps, block positive operators and entanglement witnesses with problems related to multivariate polynomials. For instance, we show how indecomposable block positive operators relate to biquadratic forms that are not sums of squares. Although the general problem of describing the set of positive maps remains open, in some particular cases we solve the corresponding polynomial inequalities and obtain explicit conditions for positivity.

  2. Global Arrays

    SciTech Connect

    Krishnamoorthy, Sriram; Daily, Jeffrey A.; Vishnu, Abhinav; Palmer, Bruce J.

    2015-11-01

    Global Arrays (GA) is a distributed-memory programming model that allows for shared-memory-style programming combined with one-sided communication, to create a set of tools that combine high performance with ease-of-use. GA exposes a relatively straightforward programming abstraction, while supporting fully-distributed data structures, locality of reference, and high-performance communication. GA was originally formulated in the early 1990’s to provide a communication layer for the Northwest Chemistry (NWChem) suite of chemistry modeling codes that was being developed concurrently.

  3. Global orbit corrections

    SciTech Connect

    Symon, K.

    1987-11-01

    There are various reasons for preferring local (e.g., three bump) orbit correction methods to global corrections. One is the difficulty of solving the mN equations for the required mN correcting bumps, where N is the number of superperiods and m is the number of bumps per superperiod. The latter is not a valid reason for avoiding global corrections, since, we can take advantage of the superperiod symmetry to reduce the mN simultaneous equations to N separate problems, each involving only m simultaneous equations. Previously, I have shown how to solve the general problem when the machine contains unknown magnet errors of known probability distribution; we made measurements of known precision of the orbit displacements at a set of points, and we wish to apply correcting bumps to minimize the weighted rms orbit deviations. In this report, we will consider two simpler problems, using similar methods. We consider the case when we make M beam position measurements per superperiod, and we wish to apply an equal number M of orbit correcting bumps to reduce the measured position errors to zero. We also consider the problem when the number of correcting bumps is less than the number of measurements, and we wish to minimize the weighted rms position errors. We will see that the latter problem involves solving equations of a different form, but involving the same matrices as the former problem.

  4. Globalization and the Inward Flow of Immigrants: Issues Associated with the Inpatriation of Global Managers

    ERIC Educational Resources Information Center

    Harvey, Michael; Kiessling, Tim; Moeller, Miriam

    2011-01-01

    Assembling a diverse global workforce is becoming a critical dimension in gaining successful global performance. In the past, staffing has focused on control of the multinational organization as the primary goal when staffing overseas positions. As organizations globalize their operations, the goal of staffing is shifting from control to…

  5. Seeking Critical Hope in a Global Age: Religious Education in a Global Perspective

    ERIC Educational Resources Information Center

    Kim, Hyun-Sook

    2015-01-01

    During the last two decades, globalization has come to occupy an important position in popular and academic discourses. Globalization has provided opportunities to produce possibilities of global awareness and at the same time crises to perpetuate a culture of fear. This article asks how church and religious education can provide a global…

  6. Global teaching of global seismology

    NASA Astrophysics Data System (ADS)

    Stein, S.; Wysession, M.

    2005-12-01

    Our recent textbook, Introduction to Seismology, Earthquakes, & Earth Structure (Blackwell, 2003) is used in many countries. Part of the reason for this may be our deliberate attempt to write the book for an international audience. This effort appears in several ways. We stress seismology's long tradition of global data interchange. Our brief discussions of the science's history illustrate the contributions of scientists around the world. Perhaps most importantly, our discussions of earthquakes, tectonics, and seismic hazards take a global view. Many examples are from North America, whereas others are from other areas. Our view is that non-North American students should be exposed to North American examples that are type examples, and that North American students should be similarly exposed to examples elsewhere. For example, we illustrate how the Euler vector geometry changes a plate boundary from spreading, to strike-slip, to convergence using both the Pacific-North America boundary from the Gulf of California to Alaska and the Eurasia-Africa boundary from the Azores to the Mediterranean. We illustrate diffuse plate boundary zones using western North America, the Andes, the Himalayas, the Mediterranean, and the East Africa Rift. The subduction zone discussions examine Japan, Tonga, and Chile. We discuss significant earthquakes both in the U.S. and elsewhere, and explore hazard mitigation issues in different contexts. Both comments from foreign colleagues and our experience lecturing overseas indicate that this approach works well. Beyond the specifics of our text, we believe that such a global approach is facilitated by the international traditions of the earth sciences and the world youth culture that gives students worldwide common culture. For example, a video of the scene in New Madrid, Missouri that arose from a nonsensical earthquake prediction in 1990 elicits similar responses from American and European students.

  7. Global Geomorphology

    NASA Technical Reports Server (NTRS)

    Douglas, I.

    1985-01-01

    Any global view of landforms must include an evaluation of the link between plate tectonics and geomorphology. To explain the broad features of the continents and ocean floors, a basic distinction between the tectogene and cratogene part of the Earth's surface must be made. The tectogene areas are those that are dominated by crustal movements, earthquakes and volcanicity at the present time and are essentially those of the great mountain belts and mid ocean ridges. Cratogene areas comprise the plate interiors, especially the old lands of Gondwanaland and Laurasia. Fundamental as this division between plate margin areas and plate interiors is, it cannot be said to be a simple case of a distinction between tectonically active and stable areas. Indeed, in terms of megageomorphology, former plate margins and tectonic activity up to 600 million years ago have to be considered.

  8. Global warming

    NASA Astrophysics Data System (ADS)

    Houghton, John

    2005-06-01

    'Global warming' is a phrase that refers to the effect on the climate of human activities, in particular the burning of fossil fuels (coal, oil and gas) and large-scale deforestation, which cause emissions to the atmosphere of large amounts of 'greenhouse gases', of which the most important is carbon dioxide. Such gases absorb infrared radiation emitted by the Earth's surface and act as blankets over the surface keeping it warmer than it would otherwise be. Associated with this warming are changes of climate. The basic science of the 'greenhouse effect' that leads to the warming is well understood. More detailed understanding relies on numerical models of the climate that integrate the basic dynamical and physical equations describing the complete climate system. Many of the likely characteristics of the resulting changes in climate (such as more frequent heat waves, increases in rainfall, increase in frequency and intensity of many extreme climate events) can be identified. Substantial uncertainties remain in knowledge of some of the feedbacks within the climate system (that affect the overall magnitude of change) and in much of the detail of likely regional change. Because of its negative impacts on human communities (including for instance substantial sea-level rise) and on ecosystems, global warming is the most important environmental problem the world faces. Adaptation to the inevitable impacts and mitigation to reduce their magnitude are both necessary. International action is being taken by the world's scientific and political communities. Because of the need for urgent action, the greatest challenge is to move rapidly to much increased energy efficiency and to non-fossil-fuel energy sources.

  9. Global gamesmanship.

    PubMed

    MacMillan, Ian C; van Putten, Alexander B; McGrath, Rita Gunther

    2003-05-01

    Competition among multinationals these days is likely to be a three-dimensional game of global chess: The moves an organization makes in one market are designed to achieve goals in another in ways that aren't immediately apparent to its rivals. The authors--all management professors-call this approach "competing under strategic interdependence," or CSI. And where this interdependence exists, the complexity of the situation can quickly overwhelm ordinary analysis. Indeed, most business strategists are terrible at anticipating the consequences of interdependent choices, and they're even worse at using interdependency to their advantage. In this article, the authors offer a process for mapping the competitive landscape and anticipating how your company's moves in one market can influence its competitive interactions in others. They outline the six types of CSI campaigns--onslaughts, contests, guerrilla campaigns, feints, gambits, and harvesting--available to any multiproduct or multimarket corporation that wants to compete skillfully. They cite real-world examples such as the U.S. pricing battle Philip Morris waged with R.J. Reynolds--not to gain market share in the domestic cigarette market but to divert R.J. Reynolds's resources and attention from the opportunities Philip Morris was pursuing in Eastern Europe. And, using data they collected from their studies of consumer-products companies Procter & Gamble and Unilever, the authors describe how to create CSI tables and bubble charts that present a graphical look at the competitive landscape and that may uncover previously hidden opportunities. The CSI mapping process isn't just for global corporations, the authors explain. Smaller organizations that compete with a portfolio of products in just one national or regional market may find it just as useful for planning their next business moves.

  10. Classroom Climate, Global Knowledge, Global Attitudes, Political Attitudes.

    ERIC Educational Resources Information Center

    Blankenship, Glen

    1990-01-01

    Examines how an open classroom climate relates to effective global education. Looks at gender and race differences, and identifies attributes of open classrooms. Administers questionnaires to 202 students enrolled in an international studies program. Finds a moderate positive correlation between classroom climate and student political attitudes.…

  11. Positive amplitudes in the amplituhedron

    NASA Astrophysics Data System (ADS)

    Arkani-Hamed, Nima; Hodges, Andrew; Trnka, Jaroslav

    2015-08-01

    The all-loop integrand for scattering amplitudes in planar SYM is determined by an "amplitude form" with logarithmic singularities on the boundary of the amplituhedron. In this note we provide strong evidence for a new striking property of the superamplitude, which we conjecture to be true to all loop orders: the amplitude form is positive when evaluated inside the amplituhedron. The statement is sensibly formulated thanks to the natural "bosonization" of the superamplitude associated with the amplituhedron geometry. However this positivity is not manifest in any of the current approaches to scattering amplitudes, and in particular not in the cellulations of the amplituhedron related to on-shell diagrams and the positive grassmannian. The surprising positivity of the form suggests the existence of a "dual amplituhedron" formulation where this feature would be made obvious. We also suggest that the positivity is associated with an extended picture of amplituhedron geometry, with the amplituhedron sitting inside a co-dimension one surface separating "legal" and "illegal" local singularities of the amplitude. We illustrate this in several simple examples, obtaining new expressions for amplitudes not associated with any triangulations, but following in a more invariant manner from a global view of the positive geometry.

  12. Globalization and Education in Japan

    ERIC Educational Resources Information Center

    Ohkura, Kentaro; Shibata, Masako

    2009-01-01

    In this paper, the authors contend that globalization in Japan is the gradual process in which Japan's positioning of "self" within international relations, which had formerly been dominated by the West, has changed. Accordingly, Japan's relationships with the West and the rest of the world, for example, Asia, have also been reviewed and modified.…

  13. Chemical Tracking Systems: Not Your Usual Global Positioning System!

    ERIC Educational Resources Information Center

    Roy, Ken

    2007-01-01

    The haphazard storing and tracking of chemicals in the laboratory is a serious safety issue facing science teachers. To get control of your chemicals, try implementing a "chemical tracking system". A chemical tracking system (CTS) is a database of chemicals used in the laboratory. If implemented correctly, a CTS will reduce purchasing costs,…

  14. New Time and Multipath Augmentations for the Global Positioning System

    NASA Astrophysics Data System (ADS)

    Pratt, John A.

    Although developed with a narrow focus in mind, use of GPS has expanded into dozens of fields in industry, science, and military applications. The purpose of the research detailed in this dissertation is an increase in the utility of GPS by improving primary applications of the constellation and expand the practicality of some secondary applications. The first portion of this disseration focuses on the development of clock estimation algorithms for a GPS aiding system called iGPS which has been designed to improve the performance of the system in challenging environments. Central to the functioning of iGPS are the Iridium communication satellites. This dissertation describes a Kalman filter for estimating Iridium satellite clock biases from GPS-like measurements at an interval of 10 s. Typical results show the current filter to be accurate to within 200 ns while always meeting the initial system specification of half a microsecond. The following chapter examines the expediency of increasing the number of terms used to represent the clock bias in the broadcast message and it is shown that the current broadcast message is sufficient. The second half of the dissertation deals with the use of GPS multipath as an environmental measurement. It is shown that reflections of GPS signals from the ground can be used to estimate several important phenological indicators relative to the vegetation surrounding the GPS antenna. Methods are developed for refining the reflected signal and preparing it for use as a vegetation index. Finally, the effect of temperature and multipath supression algorithms on the GPS multipath data is examined relative to its viability for use as previously described. It is shown that these effects are minor in the majority of the GPS sites used in this study and that the data can be adjusted to avoid temperature difficulties.

  15. A marine direction finding system based on global positioning system

    NASA Astrophysics Data System (ADS)

    Dǎnişor, Alin; Izet-Ünsalan, Kunsel-Özel; Ünsalan, Deniz; Tamaş, Razvan; Dǎnişor, Cosmin

    2015-02-01

    Direction finding and attitude determination is of utmost importance for marine, aerial, spatial and land-based navigation [1], as well as control of vehicles, in surveying and in target acquisition of tracking radars. These problems can be solved using dedicated sensors commonly named as compasses and rate gyros. Unfortunately, the classical means of attitude determination both by magnetic and gyrocompasses become unusable at extreme latitudes. Furthermore, gyrocompasses inherently yield erroneous results on high speed craft. Three-axis attitude of a vehicle can be determined using a GPS receiver with multiple antennas, by measuring carrier phases [2], signal strength [3], or integrated INS/GPS systems [4]. This paper proposes a new method of attitude determination using two low-cost GPS receivers.

  16. Shuttle Global Positioning System (GPS) system design study

    NASA Technical Reports Server (NTRS)

    Nilsen, P. W.

    1979-01-01

    The various integration problems in the Shuttle GPS system were investigated. The analysis of the Shuttle GPS link was studied. A preamplifier was designed since the Shuttle GPS antennas must be located remotely from the receiver. Several GPS receiver architecture trade-offs were discussed. The Shuttle RF harmonics and intermode that fall within the GPS receiver bandwidth were analyzed. The GPS PN code acquisition was examined. Since the receiver clock strongly affects both GPS carrier and code acquisition performance, a clock model was developed.

  17. US EPA GLOBAL POSITIONING SYSTEMS - TECHNICAL IMPLEMENTATION GUIDANCE

    EPA Science Inventory

    The U.S. EPA Geospatial Quality Council (GQC) was formed in 1998 to provide Quality Assurance guidance for the development, use, and products of geospatial activities and research. The long-term goals of the GQC are expressed in a living document, currently the EPA Geospatial Qua...

  18. Digitally Synthesized Phased Antenna for Multibeam Global Positioning

    NASA Technical Reports Server (NTRS)

    Dunn, Charles E. (Inventor); Young, Lawrence E. (Inventor)

    2004-01-01

    In a system according to the proposed technique, the signal received by each element of the array antenna would be subjected to downconversion, and spread-spectrum demodulation and correlation as necessary; this processing would be performed separately from, and simultaneously with, similar processing of signals received by the other antenna elements. For the GPS implementation, following downconversion to baseband, the signals would be digitized, and all subsequent processing would be digital. In In the digital process, residual carriers would be removed and each signal would be correlated with a locally generated model pseudo random-noise code, all following normal GPS procedure. As part of this procedure, accumulated values would be added in software and the resulting signals would be phase-shifted in software by the amounts necessary to synthesize the desired antenna directional gain pattern of peaks and nulls. The principal advantage of this technique over the conventional radio-frequency-combining technique is that the parallel digital baseband processing of the signals from the various antenna elements would be a relatively inexpensive and flexible means for exploiting the inherent multiple-peak/multiple-null aiming capability of a phased-array antenna. In the original intended GPS application, the peaks and nulls could be directed independently for each GPS signal being tracked by the GPS receiver. This will improve the SNR simultaneously for each GPS signal being tracked while steering multiple nulls toward sources of interference. The technique could also be applied to other code-division multiple-access communication systems.

  19. Digitally synthesized phased antenna for multibeam global positioning

    NASA Technical Reports Server (NTRS)

    Dunn, Charles E. (Inventor); Young, Lawrence E. (Inventor)

    2004-01-01

    In a system according to the proposed technique (see figure), the signal received by each element of the array antenna would be subjected to downconversion, and spread-spectrum demodulation and correlation as necessary; this processing would be performed separately from, and simultaneously with, similar processing of signals received by the other antenna elements. For the GPS implementation, following downconversion to baseband, the signals would be digitized, and all subsequent processing would be digital. In the digital process, residual carriers would be removed and each signal would be correlated with a locally generated model pseudo random-noise code, all following normal GPS procedure. As part of this procedure, accumulated values would be added in software and the resulting signals would be phase-shifted in software by the amounts necessary to synthesize the desired antenna directional gain pattern of peaks and nulls. The principal advantage of this technique over the conventional radio-frequency-combining technique is that the parallel digital baseband processing of the signals from the various antenna elements would be a relatively inexpensive and flexible means for exploiting the inherent multiple-peak/multiple-null aiming capability of a phased-array antenna. In the original intended GPS application, the peaks and nulls could be directed independently for each GPS signal being tracked by the GPS receiver. This will improve the SNR simultaneously for each GPS signal being tracked while steering multiple nulls toward sources of interference. The technique could also be applied to other code-division multiple-access communication systems.

  20. Strategies for high-precision Global Positioning System orbit determination

    NASA Technical Reports Server (NTRS)

    Lichten, Stephen M.; Border, James S.

    1987-01-01

    Various strategies for the high-precision orbit determination of the GPS satellites are explored using data from the 1985 GPS field test. Several refinements to the orbit determination strategies were found to be crucial for achieving high levels of repeatability and accuracy. These include the fine tuning of the GPS solar radiation coefficients and the ground station zenith tropospheric delays. Multiday arcs of 3-6 days provided better orbits and baselines than the 8-hr arcs from single-day passes. Highest-quality orbits and baselines were obtained with combined carrier phase and pseudorange solutions.