Science.gov

Sample records for non-differential global positioning

  1. The Global Positioning System

    DTIC Science & Technology

    1989-05-01

    Global Positioning System ( GPS ) and current program status are provided. The importance of...the NAVSTAR Global Positioning System (NAVSTAR GPS or GPS ) will have on future weapons employment. The study will: examine why we need a high...Washington, D.C., 24 January, 1984. Malone, Daniel K. GPS /NAVSTAR. Military Review, March 1986. Nepean, Phillip The NAVSTAR Global Positioning System

  2. NAVSTAR Global Positioning System.

    DTIC Science & Technology

    1988-04-01

    number) The NAVSTAR Global Positioning System ( GPS ) is an all-weather, Jam-resistant, continuous-operations space-based, passive radio navigation and...with an understanding of the capabilities and limitations of the NAVSTAR Global Positioning System ( GPS ). II. Problem: To fight the next battle...navigation equipment and was not able to navigate on instruments or across a distant 9000-foot mountain. Had a NAVSTAR Global Positioning System ( GPS

  3. Global Positioning System Status

    DTIC Science & Technology

    2011-04-27

    GPS : FREE – DEPENDABLE – RELIABLE - ACCURATE 1 GLOBAL POSITIONING SYSTEM STATUS Benjamin Barbour Major, United States Air Force Schriever AFB... Global Positioning System Service Interface Committee (CGSIC) held in Groton, CT, April 2011 14. ABSTRACT 15. SUBJECT TERMS 16. SECURITY...Continuing work with international GNSS community  Maintains Backward Compatibility  Managing GPS systems and supporting stakeholders Committed to responsible stewardship of GPS

  4. Absolute Positioning Using the Global Positioning System

    DTIC Science & Technology

    1994-04-01

    Global Positioning System ( GPS ) has becom a useful tool In providing relativ survey...Includes the development of a low cost navigator for wheeled vehicles. ABSTRACT The Global Positioning System ( GPS ) has become a useful tool In providing...technique of absolute or point positioning involves the use of a single Global Positioning System ( GPS ) receiver to determine the three-dimenslonal

  5. 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.

  6. Global Positioning Systems in Combat

    DTIC Science & Technology

    2007-11-26

    Global Positioning Systems ( GPS ) in combat. Fratricide has been reduced because of the effective use of...gained by the use of Global Positioning Systems ( GPS ) in combat. Fratricide has been reduced because of the effective use of GPS in common equipment...The advantages of using Global Positioning Systems ( GPS ) in combat have proven to reduce fratricide, collateral damage, and the number of

  7. Global Positioning System (GPS) Modernization

    DTIC Science & Technology

    2001-01-01

    GLOBAL POSITIONING SYSTEM ( GPS ) MODERNIZATION Lt. Col. C. McGinn, Capt. S...CA 90501, USA Abstract The Global Positioning System ( GPS ) signal is now the primary means of obtaining precise time to an internationally accepted...number. 1. REPORT DATE NOV 2000 2. REPORT TYPE 3. DATES COVERED 00-00-2000 to 00-00-2000 4. TITLE AND SUBTITLE Global Positioning System ( GPS

  8. NAVSTAR Global Positioning System Overview

    DTIC Science & Technology

    1984-04-10

    Global Positioning System ( GPS ) is an all-weather, space-based navigation system under development by the Department of Defense (DoD...Happing Agency Los Angeles, California 90009 ABSTRACT The Navstar Global Positioning System ( GPS ) is an all-weather, space-based navigation system ...TITLE llnclud* Security Clauiti.ati-n) NAVSTAR Global Positioning System Overview N/A PROJECT NO. N/A TASK NO. N/A WORK UNIT NO.

  9. Global Positioning Satellite Recorder

    SciTech Connect

    Reeves, George

    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 prior to operation. The vehicle combines GPS technology and a cpu with custom software to accomplish the task.

  10. Global Positioning System Navigation Algorithms

    DTIC Science & Technology

    1977-05-01

    Historical Remarks on Navigation In Greek mythology , Odysseus sailed safely by the Sirens only to encounter the monsters Scylla and Charybdis...TNED 000 00 1(.7 BIBLIOGRAPHY 1. Pinsent, John. Greek Mythology . Paul Hamlyn, London, 1969. 2. Kline, Morris. Mathematical Thought from Ancient to...Algorithms 20. ABS AACT (Continue an reverse sid* If necessary and identify by block nttrnber) The Global Positioning System (CPS) will be a constellation of

  11. GPS (Global Positioning System) Range Applications Study.

    DTIC Science & Technology

    1982-12-31

    Global Positioning System ( GPS ) as a source of Time i. Space Position ...THE ANALYTIC SCIENCES CORPORATION 2. GPS OVERVIEW This chapter provides a short, general introduction to the Global Positioning System ( GPS ) and...chapters. 2.1 SYSTEM OPERATION The NAVSTAR Global Positioning System ( GPS ) is a space- based radio navigation system designed to provide users with

  12. Texas Instruments 4100 GPS (Global Positioning System) Positioning Software

    DTIC Science & Technology

    1986-09-01

    Global Positioning System ( GPS ). To meet...solutions as correct before accepting them. 9 II, BACKGROUND A. GLOBAL POSITIONING SYSTEM GPS is a universal satellite poitioning system that is...ABBREVIATIONS AND ACRONYMS GPS = Global Positioning System NPS = Naval Postgraduate School Montcrey CA DMA Defense Mapping Agency NOAA = National Oceanic

  13. Airborne Global Positioning System Antenna System

    DTIC Science & Technology

    2004-10-14

    GLOBAL POSITIONING SYSTEM ANTENNA SYSTEM DISTRIBUTION: SMC/ GP (3 cys); AFFSA...standard that airborne Global Positioning System ( GPS ) antenna system must meet to be identified with the applicable MSO marking. The similarity of...UNCLASSIFIED DOCUMENT NO. DATE NO. MSO-C144 14 Oct 04 Initial Release REV: REV: SHEET 1 OF 16 TITLE: AIRBORNE GLOBAL POSITIONING SYSTEM

  14. Global Positioning System III (GPS III)

    DTIC Science & Technology

    2013-12-01

    Global Positioning System III ( GPS III) As of FY 2015 President’s Budget...00-00-2013 to 00-00-2013 4. TITLE AND SUBTITLE Global Positioning System III ( GPS III) 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT...Responsible Office References Program Name Global Positioning System III ( GPS III) DoD Component Air Force

  15. Global Positioning System (GPS) Geodetic Receivers,

    DTIC Science & Technology

    1982-02-08

    Subti.) S. TYPE OF REPORT A PERFo COVERED Global Positioning System ( GPS ) Geodetic N/A Receivers S. PERFORMING OrG. REPORT NUMBER I N/A AUTNORf*) S...i N meueaed idautfy b block nmAr) The NAVSTAR Global Positioning System ( GPS ) when fully developed will pro- vide world-wide, all weather, continuous... Global Positioning System ( GPS ) when fully developed will provide world-wide, all weather, continuous, highly accurate radio navigation support to

  16. Global Positioning System Constellation Clock Performance

    DTIC Science & Technology

    2002-12-01

    of the Global Positioning System ( GPS ) constellation with respect to the lifetimes of space vehicles and space vehicle clocks, both active and...ABSTRACT An overview of the Global Positioning System ( GPS ) constellation with respect to the lifetimes of space vehicles and space vehicle clocks, both...34th Annual Precise Time and Time Interval (PTTI) Meeting 77 GLOBAL POSITIONING SYSTEM CONSTELLATION CLOCK PERFORMANCE Jay Oaks and Marie

  17. Global Positioning System Shipborne Reference System

    DTIC Science & Technology

    1997-09-30

    Office of Naval Research Space and Remote Sensing 1997 Annual Report 1 GLOBAL POSITIONING SYSTEM SHIPBORNE REFERENCE SYSTEM James R. Clynch...N00014-97-WR30044 LONG-TERM GOAL The long term goal is to improve the navigation capability of naval vessels using the Global Positioning System ...COVERED 00-00-1997 to 00-00-1997 4. TITLE AND SUBTITLE Global Positioning System Shipborne Reference System 5a. CONTRACT NUMBER 5b. GRANT

  18. GPSR. Global Positioning Satellite Recorder

    SciTech Connect

    Reeves, G.

    1994-10-01

    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 prior to operation. The vehicle combines GPS technology and a cpu with custom software to accomplish the task.

  19. 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)

  20. 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)

  1. 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…

  2. 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.

  3. 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,…

  4. 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.

  5. The Global Positioning System: Assessing National Policies,

    DTIC Science & Technology

    1995-01-01

    WASSEM • MONICA PINTO CRITICAL TECHNOLOGIES INSTITUTE RAND The research described in this report was supported by RAND’s Critical...MONICA PINTO Prepared for the Executive Office of the President Office of Science and Technology Policy CRITICAL TECHNOLOGIES INSTITUTE RAND...National Research Council Committee on the Future of the Global Positioning System, Washington, D.C., July 28-30,1994. Barbier, Jacques , and Thierry

  6. 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.

  7. High dynamic global positioning system receiver

    NASA Technical Reports Server (NTRS)

    Hurd, W. J. (Inventor)

    1986-01-01

    A Global Positioning System (GPS) receiver having a number of channels, receives an aggregate of pseudorange code time division modulated signals. The aggregate is converted to baseband and then to digital form for separate processing in the separate channels. A fast fourier transform processor computes the signal energy as a function of Doppler frequency for each correlation lag, and a range and frequency estimator computes estimates of pseudorange, and frequency. Raw estimates from all channels are used to estimate receiver position, velocity, clock offset and clock rate offset in a conventional navigation and control unit, and based on the unit that computes smoothed estimates for the next measurement interval.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Relativity in the Global Positioning System.

    PubMed

    Ashby, Neil

    2003-01-01

    The Global Positioning System (GPS) uses accurate, stable atomic clocks in satellites and on the ground to provide world-wide position and time determination. These clocks have gravitational and motional frequency shifts which are so large that, without carefully accounting for numerous relativistic effects, the system would not work. This paper discusses the conceptual basis, founded on special and general relativity, for navigation using GPS. Relativistic principles and effects which must be considered include the constancy of the speed of light, the equivalence principle, the Sagnac effect, time dilation, gravitational frequency shifts, and relativity of synchronization. Experimental tests of relativity obtained with a GPS receiver aboard the TOPEX/POSEIDON satellite will be discussed. Recently frequency jumps arising from satellite orbit adjustments have been identified as relativistic effects. These will be explained and some interesting applications of GPS will be discussed.

  14. Airborne Supplemental Navigation Equipment Using The Global Positioning System (GPS) Precise Positioning Service (PPS)

    DTIC Science & Technology

    2002-08-30

    Global Positioning System ( GPS ) Precise Positioning ...The Global Positioning System ( GPS ) Precise Positioning Service (PPS) 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S...EQUIPMENT USING THE GLOBAL POSITIONING SYSTEM ( GPS ) / PRECISE POSITIONING SERVICE (PPS) DISTRIBUTION: SMC/CZ (3 cys); AFFSA; NAWCAD; ESC/GA; SPAWAR Code

  15. Airborne Supplemental Navigation Equipment Using the Global Positioning System (GPS)/Precise Positioning Service (PPS)

    DTIC Science & Technology

    2005-10-13

    GLOBAL POSITIONING SYSTEM ( GPS ) I PRECISE POSITIONING SERVICE (PPS) MSO RELEASE AUTHORIZED BY: ttl~ .. J ,M~·., Configurat!fJ...Equipment Using The Global Positioning System ( GPS )/ Precise Positioning Service (PPS) 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER...EQUIPMENT USING THE GLOBAL POSITIONING SYSTEM ( GPS ) / PRECISE POSITIONING SERVICE (PPS) DISTRIBUTION: SMC/ GP (5

  16. Management: Global positioning and wireless dispatching

    SciTech Connect

    Wood, M.

    1996-02-01

    Over the last several years, my company has been supplying many service companies with wireless dispatching solutions. Recently the impact of the system has been greatly increased with the introduction of a GPS (Global Position Systems) interface. This adds visual recognition as to the whereabouts of each vehicle within the customer service area. The only equipment required in the field for GPS is a transmit/receive device and a wireless modem, one mounted out of the way in the vehicle (under the seat) and a {open_quotes}hockey puck{close_quotes} size unit on the roof of the vehicle. The GPS received unit and wireless modem are used to retrieve the longitude, latitude and ground speed coordinates and transmit them back to the host system.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Interferometric Determination of GPS (Global Positioning System) Satellite Orbits.

    DTIC Science & Technology

    1985-04-23

    Global Positioning System ,’ GPS interferometrv...INTRODUCTION If the NAVSTAR Global Positioning System ( GPS ) is to be useful for crustal motion monitoring, the orbits of the GPS satellites 7will need to be... Global Position . * ing System , April 15-19, 1985, Rockville, MD 19. KEY WORDS (Continue on rev’erse side if necessary and Identity by block

  2. Global positioning automatic vehicle location system

    SciTech Connect

    Papatheofanis, B.J.; Hasenack, M.L.; Teller, R.T.; Ramsey, G.F.

    1997-03-01

    Los Alamos National Laboratory (LANL) is a unique facility covering over 43 square miles. The Emergency Management and Response Office (EM&R) is required to respond, provide Incident Command (IC), and coordination for all Laboratory emergencies. This requires IC`s and support staff to respond to the actual scene of the incident. Since the IC is under numerous constraints and stress, the office wanted the capability of locating the EM&R vehicles on an electronic map. An automated vehicle location (AVL) system was required for the additional safety of the emergency response personal. The requirements for the AVL system include total automatic tracking and low cost. After careful consideration, it was determined that the most efficient and cost effective system would be based on packet radio technology as the transmission media. The location is determined by the Department of Defense Global Positioning System (GPS). The system that was designed and constructed required four components to be interfaced and communicate with each other. The first component was a GPS receiver which actually provides the location information, equipped with a digital interface to communicate location information remotely. The second component is a modem that interfaces the GPS digital interface information to a radio. The third component is the radio itself which allows for the actual information transfer from the remote GPS receiver and modem. The fourth component is the software package that provides moving maps and displays the vehicle location on that map. The equipment was all commercial off-the-shelf that only required proper integration and packaging for the AVL application. This paper describes the steps taken in the integration of the equipment into the AVL package.

  3. 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.

  4. Dynamic Positioning at Sea Using the Global Positioning System.

    DTIC Science & Technology

    1987-06-01

    sampled with a period of about 19 s. Computed headings were tried to improve the rate but tests indicated that the real data, even with a low sampling rate was...coordinates of Mini-Ranger and GPS positions are expressed in meters. Due to the low sampling rate of the existing course data, only data from steady

  5. Precision Position, Navigation, and Timing without the Global Positioning System

    DTIC Science & Technology

    2011-01-01

    timing] in GPS - denied environments” as one of the top 12 (in terms of priority) re- search areas that we should emphasize in the near future.6...Navigation Techniques for Position, Navigation, and Timing in GPS - Denied Environments Navigation Using Beacons Beacons (i.e., sources of man-made...wishes to succeed in maintaining precision navigation in GPS - denied environments.  Wright-Patterson AFB, Ohio Platform Dynamics Precise Navigation

  6. Non-differential drive axle

    SciTech Connect

    Hardt, J.G.; Shea, D.W.

    1987-02-17

    This patent describes a drive axle for a vehicle, the vehicle having a set of wheels spaced along a first axis of rotation of the wheels, the drive axle comprising: a housing adapted to extend generally along the first axis between the two wheels, the housing first and second axially spaced ends, a gear support rotatably journalled in the housing adjacent the first end of the housing, an intermediate shaft drivingly connected to the gear support and rotatably journalled in the housing adjacent the second end of the housing, a first output shaft rotatably journalled in the first end of the housing and the gear support, a second output shaft rotatably journalled in the second end of the housing and the intermediate shaft, and a first bi-directional overrunning clutch positioned adjacent the first end of the housing and operable to connect the first output shaft with the gear support for conjoint rotation. The first overrunning clutch includes a first non-circular surface on the gear support, a first drum connected to the first output shaft and overlying the first non-circular surface, and rollers disposed between the first drum and the first non-circular surface actuatable to connect the first drum and the first non-circular surface for conjoint rotation.

  7. No Longer Guaranteed...Global Positioning System Alternative Necessary

    DTIC Science & Technology

    2003-01-01

    enemy position and movement. The military’s use of the global positioning system ( GPS ) has created a sig- nificant military advantage in accurate...2003 2. REPORT TYPE 3. DATES COVERED 00-00-2003 to 00-00-2003 4. TITLE AND SUBTITLE No Longer Guaranteed... Global positioning system alternative...access, there are now no sufficiently secure, jam-resistant, precision positioning devices or systems . Accordingly, there is a need for a non- GPS

  8. Global Positions and Velocities from One Year of GPS Data

    NASA Technical Reports Server (NTRS)

    Heflin, M. B.; Blewitt, G.; Jefferson, D.; Vigue, Y.; Webb, F.; Zumberge, J.; Argus, D.; Gipson, J.; Ma, C.; Clark, T.

    1993-01-01

    A generalized no-fiducial approach has been developed to obtain global positions and velocities without fixing any individual position or velocity components. The method used can be applied to any global geodetic technique and proceeds in three general steps. First, daily solutions derived with weak constraints are combined to yield one global set of positions and velocities. Second, 14 minimal constraints are applied to remove uncertainties due to the loosely defined reference frame. Third, transformation from one reference frame to another is accomplished with a 14 parameter transformation. One year of daily FLINN solutions, each made with data from about 40 sites, have been combined to yield our best fit global model...

  9. 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…

  10. 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…

  11. Euthanasia: India's position in the global scenario.

    PubMed

    Shekhar, Skand; Goel, Ashish

    2013-11-01

    Euthanasia requests have increased as the number of debilitated patients rises in both developed and developing countries such as India due to medical, psychosocial-emotional, socioenvironmental, and existential issues amid fears of potential misuse. WORLD'S POSITION: Albania, Colombia, the Netherlands, and Switzerland permit euthanasia conditionally. Australia's legalization of euthanasia has been withdrawn. The United States permits withdrawal of life support. Mexico and Norway permit active euthanasia. INDIA'S POSITION: Following the Aruna Shanbaug case the Supreme Court granted legal sanction to passive, but not active, euthanasia that is valid till the Parliament legislates on euthanasia. HANDLING EUTHANASIA REQUESTS: Acknowledging the complexity of the problem; individualizing the palliative approach; and accepting the 'There is no alternative' or 'There is no answer' (TINA) factor.

  12. Civil Access to the Precise Positioning Service of the NAVSTAR Global Positioning System

    DTIC Science & Technology

    1986-12-01

    POSITIONING SERVICE OF THE NAVSTAR GLOBAL POSITIONING SYSTEM Michael J. E l l e t t Navstar GPS Joint Program Office...will only apply to Precise Positioning Service configured, code-tracking GPS receivers. Introduction The NAVSTAR Global Positioning System ( GPS ...is the second space-based navigation positioning system to be developed by the United States. The GPS will enter the operational phase within

  13. A Consistent Geodetic Reference System for GPS (Global Positioning System).

    DTIC Science & Technology

    1987-02-27

    reliable and accurate Operational Control System (OCS) is a prerequisite for successful Global Positioning System ( GPS ) navigation performance. The OCS...DDOR Doubly differenced (between station pair and Navstar pair) phase data GPS Global Positioning System MIT Massachusetts Institute of Technology...FWft SOTR4as-2 A Consistent Geodetic Reference System for GPS A. S. LIU Systems and Computer Engineering Division Engineering Group The Aerospace

  14. 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.

  15. 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)

  16. 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)

  17. Global Positioning System (GPS): Current status and possible nursery uses

    Treesearch

    Dick Karsky

    2002-01-01

    The GPS (Global Positioning System) is a worldwide satellite-positioning system that was funded, installed, and continues to be operated by the U.S. Department of Defense. The navigation signals are provided free and can be used by anyone who has the equipment necessary to receive them.

  18. 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.

  19. 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

  20. Positive biodiversity-productivity relationship predominant in global forests

    USGS Publications Warehouse

    Liang, Jingjing; Crowther, Thomas W.; Picard, Nicolas; Wiser, Susan; Zhou, Mo; Alberti, Giorgio; Schulze, Ernst-Detlef; McGuire, Anthony David; ,

    2016-01-01

    The relationship between biodiversity and ecosystem productivity has been explored in detail in herbaceous vegetation, but patterns in forests are far less well understood. Liang et al. have amassed a global forest data set from >770,000 sample plots in 44 countries. A positive and consistent relationship can be discerned between tree diversity and ecosystem productivity at landscape, country, and ecoregion scales. On average, a 10% loss in biodiversity leads to a 3% loss in productivity. This means that the economic value of maintaining biodiversity for the sake of global forest productivity is more than fivefold greater than global conservation costs.

  1. 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…

  2. Global Positioning System: Challenges in Sustaining and Upgrading Capabilities Persist

    DTIC Science & Technology

    2010-09-01

    leverage GPS satellite capabilities; (3) the GPS interagency requirements process; and (4) coordination of GPS efforts with the international PNT...Lacks Detailed Guidance 30 Coordination of GPS Activities with the International Community Continues, and Some Challenges Have Been Addressed 37...Global Positioning System Abbreviations CAM Control Account Manager CWBS Contractor Work Breakdown Structure DASS Distress

  3. The Global Positioning System and its application in spacecraft navigation

    NASA Technical Reports Server (NTRS)

    Van Leeuwen, A.; Rosen, E.; Carrier, L. M.

    1979-01-01

    The paper presents an overview of the Global Positioning System (GPS) as well as a discussion of the user system parameters govering the design of a low-earth-orbit spacecraft GPS navigation system. A specific application, the Space Shuttle orbiter GPS navigation system, is discussed with particular attention given to its receiver/processor.

  4. 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.

  5. 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)

  6. 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…

  7. 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…

  8. 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)

  9. 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…

  10. Tracking elk hunters with the Global Positioning System

    Treesearch

    L. Jack Lyon; Milo G. Burcham

    1998-01-01

    Global Positioning System (GPS) units were used to record hunter locations at 15 second intervals during elk hunting expeditions. This information allowed us to examine the influence of roads on hunter behavior, and along with associated time and distance data, provide a solid foundation on which a hunter density and elk vulnerability model can be developed.

  11. 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.

  12. 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.

  13. 82 FR 18736 - Impact of Long Term Evolution Signals on Global Positioning System Receivers

    Federal Register 2010, 2011, 2012, 2013, 2014

    2017-04-21

    ... Long Term Evolution Signals on Global Positioning System Receivers AGENCY: National Institute of... project ``Impact of Long Term Evolution (LTE) signals on Global Positioning System (GPS) Devices''. At...

  14. 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

  15. Positive biodiversity-productivity relationship predominant in global forests.

    PubMed

    Liang, Jingjing; Crowther, Thomas W; Picard, Nicolas; Wiser, Susan; Zhou, Mo; Alberti, Giorgio; Schulze, Ernst-Detlef; McGuire, A David; Bozzato, Fabio; Pretzsch, Hans; de-Miguel, Sergio; Paquette, Alain; Hérault, Bruno; Scherer-Lorenzen, Michael; Barrett, Christopher B; Glick, Henry B; Hengeveld, Geerten M; Nabuurs, Gert-Jan; Pfautsch, Sebastian; Viana, Helder; Vibrans, Alexander C; Ammer, Christian; Schall, Peter; Verbyla, David; Tchebakova, Nadja; Fischer, Markus; Watson, James V; Chen, Han Y H; Lei, Xiangdong; Schelhaas, Mart-Jan; Lu, Huicui; Gianelle, Damiano; Parfenova, Elena I; Salas, Christian; Lee, Eungul; Lee, Boknam; Kim, Hyun Seok; Bruelheide, Helge; Coomes, David A; Piotto, Daniel; Sunderland, Terry; Schmid, Bernhard; Gourlet-Fleury, Sylvie; Sonké, Bonaventure; Tavani, Rebecca; Zhu, Jun; Brandl, Susanne; Vayreda, Jordi; Kitahara, Fumiaki; Searle, Eric B; Neldner, Victor J; Ngugi, Michael R; Baraloto, Christopher; Frizzera, Lorenzo; Bałazy, Radomir; Oleksyn, Jacek; Zawiła-Niedźwiecki, Tomasz; Bouriaud, Olivier; Bussotti, Filippo; Finér, Leena; Jaroszewicz, Bogdan; Jucker, Tommaso; Valladares, Fernando; Jagodzinski, Andrzej M; Peri, Pablo L; Gonmadje, Christelle; Marthy, William; O'Brien, Timothy; Martin, Emanuel H; Marshall, Andrew R; Rovero, Francesco; Bitariho, Robert; Niklaus, Pascal A; Alvarez-Loayza, Patricia; Chamuya, Nurdin; Valencia, Renato; Mortier, Frédéric; Wortel, Verginia; Engone-Obiang, Nestor L; Ferreira, Leandro V; Odeke, David E; Vasquez, Rodolfo M; Lewis, Simon L; Reich, Peter B

    2016-10-14

    The biodiversity-productivity relationship (BPR) is foundational to our understanding of the global extinction crisis and its impacts on ecosystem functioning. Understanding BPR is critical for the accurate valuation and effective conservation of biodiversity. Using ground-sourced data from 777,126 permanent plots, spanning 44 countries and most terrestrial biomes, we reveal a globally consistent positive concave-down BPR, showing that continued biodiversity loss would result in an accelerating decline in forest productivity worldwide. The value of biodiversity in maintaining commercial forest productivity alone-US$166 billion to 490 billion per year according to our estimation-is more than twice what it would cost to implement effective global conservation. This highlights the need for a worldwide reassessment of biodiversity values, forest management strategies, and conservation priorities. Copyright © 2016, American Association for the Advancement of Science.

  16. 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.

  17. An analysis of GDOP in global positioning system navigation

    NASA Astrophysics Data System (ADS)

    Fang, B. T.

    1980-10-01

    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.

  18. 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.

  19. 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.

  20. 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.)

  1. 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.)

  2. 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.)

  3. 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.)

  4. Infrastructure to support university Global Positioning System studies

    NASA Astrophysics Data System (ADS)

    Bell, Robin E.

    Global Positioning System (GPS) geodesy is one of the most important measurement technologies in modern Earth science. It has had a revolutionary impact on crustal motion research. The number of papers and talks featuring GPS is growing exponentially; new applications appear each month; and system performance continues to improve at a remarkable pace. This rapidly changing environment creates great opportunities for the University Navstar Consortium (UNAVCO) community and a bright future for continued growth.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

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

    SciTech Connect

    Vandam, T.M.; Blewitt, G.; Heflin, M.B. ||

    1994-12-01

    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.

  15. 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.

  16. 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.

  17. Global Positioning System Analysis of a High School Football Scrimmage.

    PubMed

    Gleason, Benjamin H; Sams, Matthew L; Salley, John T; Pustina, A Andrew; Stone, Michael H

    2017-08-01

    Gleason, BH, Sams, M, Salley, JT, Pustina, A, and Stone, MH. Global positioning system analysis of a high school football scrimmage. J Strength Cond Res 31(8): 2183-2188, 2017-The purpose of this study was to examine the physical demands of a high school American football scrimmage. Male high school football players (N = 25) participated in a spring scrimmage. Global positioning system data and game film were recorded throughout the entirety of the scrimmage to determine the total distance covered, the distance covered in different velocity bands, the number of accelerations and decelerations performed, and the work-to-rest ratio of the scrimmage. The athletes were divided into 2 groups: linemen (L) (N = 7) vs. nonlinemen (NL) (N = 8) for statistical analysis, and independent T-tests with Holm's sequential Bonferroni adjustment were used to determine differences in movement characteristics between the L and NL groups. Average play duration was 5.7 ± 2.1 seconds, whereas the rest interval was 33.4 ± 13.6 seconds between plays, for an overall exercise-to-rest ratio of 1:5.9. Total distance, standing and walking distance, running distance, striding distance, sprinting distance, and total high-speed running distance covered by NL was greater than L (statistically significant at p ≤ 0.05). Distances traveled in each velocity band by position and by play are also included to provide context of our findings. Data from the present study add to the pool of support for the use of position-specific training in preparing high school football players for competition.

  18. Building resilience of the Global Positioning System to space weather

    NASA Astrophysics Data System (ADS)

    Fisher, Genene; Kunches, Joseph

    2011-12-01

    Almost every aspect of the global economy now depends on GPS. Worldwide, nations are working to create a robust Global Navigation Satellite System (GNSS), which will provide global positioning, navigation, and timing (PNT) services for applications such as aviation, electric power distribution, financial exchange, maritime navigation, and emergency management. The U.S. government is examining the vulnerabilities of GPS, and it is well known that space weather events, such as geomagnetic storms, contribute to errors in single-frequency GPS and are a significant factor for differential GPS. The GPS industry has lately begun to recognize that total electron content (TEC) signal delays, ionospheric scintillation, and solar radio bursts can also interfere with daily operations and that these threats grow with the approach of the next solar maximum, expected to occur in 2013. The key challenges raised by these circumstances are, first, to better understand the vulnerability of GPS technologies and services to space weather and, second, to develop policies that will build resilience and mitigate risk.

  19. 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.

  20. 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.

  1. Absolute Positioning by Collecting Global Positioning System (GPS) Data Along Short Baselines

    DTIC Science & Technology

    1993-09-01

    BASELINES BY BRUCE R . HERMANN AND ALAN G. EVANS STRATEGIC AND SPACE SYSTEMS DEPARTMENT SEPTEMBER 1993 DTI I . ELECT’ ]0CT 22 1993 Approved for public release...NSWCDD/TR-93/309 ABSOLUTE POSITIONING BY COLLECTING GLOBAL POSITIONING SYSTEM (GPS) DATA ALONG SHORT BASELINES BY BRUCE R . HERMANN AND ALAN G. EVANS...Branch; Mr. T. Sims, Head, Space Sciences Branch; and Mr. J. Sloop, Head, Space and Surface Systems Division. ,- o" Fo, .. ,, ,Approved by: B~y. ’ " - R

  2. 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.

  3. 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.

  4. Global Positioning System, Theory and Practice, 5th Edition

    NASA Astrophysics Data System (ADS)

    Nerem, R. S.; Larson, K. M.

    The Global Positioning System (GPS) is rapidly becoming as much a part of our daily lives as the Internet, and it is now being used to navigate and locate cars, commercial and private aircraft, military vehicles, ships, spacecraft, recreational vehicles, hikers, and wildlife. In addition, GPS is becoming our primary system for precision timing and an important tool for active microwave remote sensing. Finally, in the geophysics community, GPS is the primary geodetic tool for monitoring crustal deformation.Hundreds of receivers have already been installed in areas subject to seismic and volcanic risk in the United States alone, with many more worldwide. Therefore, interest in the technical details of how the system works has rapidly increased, as evidenced by the proliferation of GPS courses in academia and professional workshops.

  5. Realizing a terrestrial reference frame using the Global Positioning System

    NASA Astrophysics Data System (ADS)

    Haines, Bruce J.; Bar-Sever, Yoaz E.; Bertiger, Willy I.; Desai, Shailen D.; Harvey, Nate; Sibois, Aurore E.; Weiss, Jan P.

    2015-08-01

    We describe a terrestrial reference frame (TRF) realization based on Global Positioning System (GPS) data alone. Our approach rests on a highly dynamic, long-arc (9 day) estimation strategy and on GPS satellite antenna calibrations derived from Gravity Recovery and Climate Experiment and TOPEX/Poseidon low Earth orbit receiver GPS data. Based on nearly 17 years of data (1997-2013), our solution for scale rate agrees with International Terrestrial Reference Frame (ITRF)2008 to 0.03 ppb yr-1, and our solution for 3-D origin rate agrees with ITRF2008 to 0.4 mm yr-1. Absolute scale differs by 1.1 ppb (7 mm at the Earth's surface) and 3-D origin by 8 mm. These differences lie within estimated error levels for the contemporary TRF.

  6. Global positioning system: a new opportunity in physical activity measurement.

    PubMed

    Maddison, Ralph; Ni Mhurchu, Cliona

    2009-11-04

    Accurate measurement of physical activity is a pre-requisite to monitor population physical activity levels and design effective interventions. Global Positioning System (GPS) technology offers potential to improve the measurement of physical activity. This paper 1) reviews the extant literature on the application of GPS to monitor human movement, with a particular emphasis on free-living physical activity, 2) discusses issues associated with GPS use, and 3) provides recommendations for future research. Overall findings show that GPS is a useful tool to augment our understanding of physical activity by providing the context (location) of the activity and used together with Geographical Information Systems can provide some insight into how people interact with the environment. However, no studies have shown that GPS alone is a reliable and valid measure of physical activity.

  7. Global positioning system: a new opportunity in physical activity measurement

    PubMed Central

    Maddison, Ralph; Ni Mhurchu, Cliona

    2009-01-01

    Accurate measurement of physical activity is a pre-requisite to monitor population physical activity levels and design effective interventions. Global Positioning System (GPS) technology offers potential to improve the measurement of physical activity. This paper 1) reviews the extant literature on the application of GPS to monitor human movement, with a particular emphasis on free-living physical activity, 2) discusses issues associated with GPS use, and 3) provides recommendations for future research. Overall findings show that GPS is a useful tool to augment our understanding of physical activity by providing the context (location) of the activity and used together with Geographical Information Systems can provide some insight into how people interact with the environment. However, no studies have shown that GPS alone is a reliable and valid measure of physical activity. PMID:19887012

  8. Libration point orbits for lunar global positioning systems

    NASA Astrophysics Data System (ADS)

    Ren, Yuan; Shan, Jinjun

    2013-04-01

    With the development of lunar exploration, a lunar global positioning system (LGPS) is demanded for both on-ground and in-flight lunar exploration missions. The traditional configuration of constellation requires at least eighteen satellites to cover the whole lunar surface continuously. In this paper, the configurations of the libration point orbits (LPOs) constellations are investigated. By using the constellations on the Earth-Moon L1 and L2 LPOs, the basic functions of the LGPS can be realized by using eight to fourteen satellites. First, the LPO and the combinations of LPOs, which can be used in the constellations of the LGPS, are investigated. The criteria and procedures of the configuration design are introduced. Second, the configurations of LPOs constellations are investigated in the Earth-Moon circular-restricted three-body problem (CR3BP). The size of the LPOs and the distribution of the satellites on these LPOs are determined by using an exhaustive algorithm and a global optimization method, respectively. The key performance parameters of these constellations are computed. Third, the constellations with good performance in the CR3BP are redesigned in the more accurate Earth-Moon based Sun-perturbed bicircular four-body problem (B4BP). Moreover, in order to avoid the ground coverage problem caused by the perturbation of the Sun, some modifications are implemented, and the configuration of the no blind area LGPS in the B4BP is obtained.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  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. 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.

  16. 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...

  17. 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,...

  18. 76 FR 27744 - Eighty-Fifth Meeting: RTCA Special Committee 159: Global Positioning System (GPS)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-12

    ... 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 meeting...), notice is hereby given for a Special Committee 159: Global Positioning System (GPS) meeting. The...

  19. Military/Civilian Mixed-Mode Global Positioning System (GPS) Receiver (MMGR)

    DTIC Science & Technology

    2004-03-01

    Global Positioning System ( GPS ) 5a...2003. 15. SUBJECT TERMS Space Vehicles, MMGR, AFRL, JPO, Mixed-Mode Global Positioning System Receiver, GPS 16. SECURITY CLASSIFICATION OF...239.18 1 Military/Civilian Mixed-Mode Global Positioning System ( GPS ) Receiver (MMGR) Andy Peczalski, Honeywell Aerospace Electronic Systems

  20. An overview of the Navstar Global Positioning System /GPS/

    NASA Astrophysics Data System (ADS)

    Zoller, C. J.

    The Navstar/Global Positioning System (GPS), a DoD program which has passed through the concept validation phase (begun in 1974), and is now in the engineering phase, is reviewed. The operational GPS system will consist of 18 satellites and will provide visibility of a minimum of four satellites at 5 deg or more above the horizon to users located anywhere on the earth, at any time, and under all weather conditions. Attention is given to the space segment, consisting of the spacecraft being launched into 10,898 nm orbit and weighing about 900 lb. Operational spacecraft are designed to have a mean mission duration of six years and a design life goal of 7.5 years. The control segment includes all the ground facilities required to support the satellite constellation. The remote monitor stations are unmanned data collection stations (under the control of a master control station), each consisting of a four-channel receiver, a C(s) frequency standard, environmental data sensor, and a computer. The GPS user equipment is briefly described. The 651 test missions, conducted between 1977 and 1979, and which employed a wide variety of test vehicles, are presented, and include tests of navigation accuracy, demonstrations of military value, environmental effects, and system characteristics.

  1. Spacecraft applications of advanced global positioning system technology

    NASA Technical Reports Server (NTRS)

    1988-01-01

    This is the final report on the Texas Instruments Incorporated (TI) simulations study of Spacecraft Application of Advanced Global Positioning System (GPS) Technology. This work was conducted for the NASA Johnson Space Center (JSC) under contract NAS9-17781. GPS, in addition to its baselined capability as a highly accurate spacecraft navigation system, can provide traffic control, attitude control, structural control, and uniform time base. In Phase 1 of this program, another contractor investigated the potential of GPS in these four areas and compared GPS to other techniques. This contract was for the Phase 2 effort, to study the performance of GPS for these spacecraft applications through computer simulations. TI had previously developed simulation programs for GPS differential navigation and attitude measurement. These programs were adapted for these specific spacecraft applications. In addition, TI has extensive expertise in the design and production of advanced GPS receivers, including space-qualified GPS receivers. We have drawn on this background to augment the simulation results in the system level overview, which is Section 2 of this report.

  2. The Global Positioning System constellation as a space weather monitor

    NASA Astrophysics Data System (ADS)

    Morley, S.; Henderson, M. G.; Woodroffe, J. R.; Brito, T. V.

    2016-12-01

    The Global Positioning System (GPS) satellites are distributed across six orbital planes and follow near-circular orbits, with a 12 hour period, at an altitude of approximately 20200 km. The six orbital planes are distributed around the Earth and are nominally inclined at 55 degrees. Energetic particle detectors have been flown on the GPS constellation for more than two decades; by February 2016 there were 23 GPS satellites equipped with energetic particle instrumentation. The Combined X-ray Dosimeter (CXD), which is flown on 21 GPS satellites, has recently been cross-calibrated against electron data from the Van Allen Probes mission, demonstrating its utility for scientific research and radiation environment specification. Recently electron and proton flux data from these instruments, for the month of January 2014, have been publicly released. We will describe the GPS constellation from the perspective of its use as a monitor for space weather, review some of the key scientific results enabled by these instruments and show some recent observations from the constellation, including the 2015 St. Patrick's Day storm. Using data from multiple satellite missions we describe the dynamics of this storm in detail.

  3. 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.

  4. 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.

  5. 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).

  6. Energetic Particle Data From the Global Positioning System Constellation

    NASA Astrophysics Data System (ADS)

    Morley, S. K.; Sullivan, J. P.; Carver, M. R.; Kippen, R. M.; Friedel, R. H. W.; Reeves, G. D.; Henderson, M. G.

    2017-02-01

    Since 2000, Los Alamos National Laboratory (LANL) Combined X-ray and Dosimeter (CXD) and Burst Detector Dosimeter for Block II-R (BDD-IIR) instruments have been fielded on Global Positioning System (GPS) satellites. Today, 21 of the 31 operational GPS satellites are equipped with a CXD detector and a further 2 carry a BDD-IIR. Each of these instruments measures a wide range of energetic electrons and protons. These data have now been publicly released under the terms of the Executive Order for Coordinating Efforts to Prepare the Nation for Space Weather Events. The specific goal of releasing space weather data from the GPS satellites is to enable broad scientific community engagement in enhancing space weather model validation and improvements in space weather forecasting and situational awareness. The time period covered by this data release is approximately 16 years, which corresponds to more than 167 satellite years of data. The large number of GPS satellites, distributed over six orbital planes, will provide important context for ongoing and historical science missions, as well as enabling new types of research not previously possible.

  7. 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).

  8. Installation Options for the NAVSTAR Global Positioning System in Surface Ships.

    DTIC Science & Technology

    1984-06-01

    Global Positioning System ( GPS ) is a highly accurate satellite based positioning and navigation system ...RD-A14B 190 INSTALLATION OPTIONS FOR THE NAYSTAR GLOBAL POSITIONING i/i SYSTEM IN SURFACE SHIPS(U) NAYAL POSTGRADUATE SCHOOL MONTEREY CA K S AMOS JUN...POSTGRADUATE SCHOOL Monterey, California DTIC CULECTE THESIS INSTALLATION OPTIONS FOR THE NAVSTAR GLOBAL POSITIONING SYSTEM IN SURFACE SHIPS by LaJ Kevin

  9. Positional differences in professional rugby league match play through the use of global positioning systems.

    PubMed

    Austin, Damien J; Kelly, Stephen J

    2013-01-01

    The current use of tracking technology in the form of global positioning systems allows for a greater analysis of locomotor activities occurring in games and a larger volume of games when compared with time-motion analysis. Therefore, the aim of this study is to be the first to analyze the physiological demands of forwards and backs throughout the entirety of an Australian professional rugby league season. The movement patterns of 185 players from a professional rugby league club were recorded during 28 National Rugby League games played in Australia during the 2010 season. The players were clustered into 2 positional groups, backs and forwards. Maximum match-play time recorded was 99 minutes and 50 seconds in a semifinal game recorded for both a forward and back. The mean total distances covered in a game for forwards and backs were 5,964 ± 696 and 7,628 ± 744 m, respectively (p < 0.05). The maximum distance recorded by a forward was 10,511 and 10,359 m for a back. The average number of occurrences in high-intensity running (>18 km·h(-1)) was 23 ± 4 and for forwards and significantly higher backs with 35 ± 8 (p < 0.05). The maximum work rate in a 10-minute block of match play was 115 and 120 m·min(-1) of play for forwards and backs, respectively. Understanding the physiological demands of a sport is important for coaches to deliver athletes optimal training programs that elicit appropriate and specific physiological adaptation. The differences in locomotor activities, which occur between positions, need to be accounted for when developing training programs.

  10. 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.

  11. 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

  12. 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

  13. The global position of the U S forest products industry

    Treesearch

    Jeffrey P. Prestemon; David N. Wear; Michaela O. Foster

    2015-01-01

    The United States’ share of global industrial roundwood production has declined since the 1990s. We reviewed data from 1961-2013 to evaluate the extent of this decline for industrial roundwood and derived secondary forest products compared to other major producing countries. We find that the U.S. global share of industrial roundwood peaked at 28 percent in 1999 but...

  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. Global asymptotic behaviour of positive solutions to a non-autonomous Nicholson's blowflies model with delays.

    PubMed

    Van Hien, Le

    2014-01-01

    This paper addresses the global existence and global asymptotic behaviour of positive solutions to a non-autonomous Nicholson's blowflies model with delays. By using a novel approach, sufficient conditions are derived for the existence and global exponential convergence of positive solutions of the model without any restriction on uniform positiveness of the per capita dead rate. Numerical examples are provided to illustrate the effectiveness of the obtained results.

  16. Differential NAVSTAR GPS (Global Positioning System) Design Concept for Harbor/Harbor Entrance Marine Navigation.

    DTIC Science & Technology

    1984-05-01

    AD-A141 665 DIFFERENTIAL NAYSTAR GPS ( GLOBAL POSIT [ONING SYSTEM ) / DESIGN CONCEPT FOR H..(U) TRANSPORTATION SYSTEMS CENTER 7 ’ CAMBRIDGE MA J VILCANS...5-3 viii 1. INTRODUCTION 1.1 BACKGROUND The NAVSTAR Global Positioning System ( GPS ) is a satellite... system which will provide global continuous navigation and position location service when it becomes operational. The NAVSTAR GPS program has been in

  17. Application of the Global Positioning System to Nearshore Hydrographic Surveys.

    DTIC Science & Technology

    1981-09-01

    London, United Kingdom, 141-17 October, 1980. the A piition o eas aa es asters Tesis , naa Logistics Review Group Report, NlkYSTA&, Global Positionino...Center Dahlgren, Virgini& 22048 241 61. Mr. Bruce Hermann Codee K-13 Naval Surface Weapons Center Dahlgren, virginia 22408 62. Texas Instruments Attn: V

  18. 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…

  19. 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.

  20. 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.

  1. Nuclear energy position in industrial and economics global

    NASA Astrophysics Data System (ADS)

    Aji, Indarta Kuncoro; Permana, Sidik

    2012-06-01

    3E (Energy, Economics and Education) are three concepts of community development, and 3E concepts are interlinked between each other. 3E concept is divided into three levels of regions, remote area or villages, small towns and metropolitan cities, and there are different problems of each region. This paper analyzes the relations between energy, economics and education in the metropolitan and industrial city. Especially the influence of nuclear energy concerning at cost production of the industrial and the contribution of education and research for nuclear energy innovation. This relation can be explained using "S-curve". The results of this study is the comparison between the product involves the use of nuclear energy or not in the production process are explained using "S-curve" and its effect on the global economics.

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

    PubMed

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

    2013-07-01

    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. 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. 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. 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.

  3. 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

  4. Global remodeling of nucleosome positions in C. elegans

    PubMed Central

    2013-01-01

    Background Eukaryotic chromatin architecture is affected by intrinsic histone-DNA sequence preferences, steric exclusion between nucleosome particles, formation of higher-order structures, and in vivo activity of chromatin remodeling enzymes. Results To disentangle sequence-dependent nucleosome positioning from the other factors, we have created two high-throughput maps of nucleosomes assembled in vitro on genomic DNA from the nematode worm Caenorhabditis elegans. A comparison of in vitro nucleosome positions with those observed in a mixed-stage, mixed-tissue population of C. elegans cells reveals that in vivo sequence preferences are modified on the genomic scale. Indeed, G/C dinucleotides are predicted to be most favorable for nucleosome formation in vitro but not in vivo. Nucleosome sequence read coverage in vivo is distinctly lower in chromosome arms than in central regions; the observed changes in apparent nucleosome sequence specificity, likely due to genome-wide chromatin remodeler activity, contribute to the formation of these megabase-scale chromatin domains. We also observe that the majority of well-positioned in vivo nucleosomes do not occupy thermodynamically favorable sequences observed in vitro. Finally, we find that exons are intrinsically more amenable to nucleosome formation compared to introns. Nucleosome occupancy of introns and exons consistently increases with G/C content in vitro but not in vivo, in agreement with our observation that G/C dinucleotide enrichment does not strongly promote in vivo nucleosome formation. Conclusions Our findings highlight the importance of both sequence specificity and active nucleosome repositioning in creating large-scale chromatin domains, and the antagonistic roles of intrinsic sequence preferences and chromatin remodelers in C. elegans. Sequence read data has been deposited into Sequence Read Archive (http://www.ncbi.nlm.nih.gov/sra; accession number SRA050182). Additional data, software and computational

  5. Differential Global Positioning System (DGPS) for Flight Testing (Global Positioning System Differentiel (DGPS) pour les Essais en vol)

    DTIC Science & Technology

    2008-10-01

    Pseudorange P-DME Precise Distance Measurement Equipment PDOP Position Dilution of Precision PISQ Poligono Sperimentale Interforze del Salto di...DGPS-Optical Tracking Systems Some flight trials were carried out in the Sardinia test range (Poligono Militare Interforze del Salto di Quirra) in...differences and triple differences. The various DGPS techniques, including carrier phase applications, are detailed in the Chapter 1 of this

  6. Application of the NAVSTAR/Global Positioning System on Instrumented Ranges

    DTIC Science & Technology

    1981-03-01

    LEVEL NAVAL POSTGRADUATE SCHOOL Monterey, California ý’N,,C 1t, L0 THES IS APPLICA±’ION OF THE NAVSTAR/GLOBAL POSITIONING SYSTEM ON INSTRUMENTED ...ViUMOIRN 4. TITLE (and Subtitle) &.TyPIE OF fE T1991 0 PICRIVO COVERED Application of the NAVSTAR/GLOBAL 4’atch13 Positioning System On Instrumented ...8217" the results of a five day demonstration conducted on an instrumented range using a Global Positioning System prototype receiver are given. It is con

  7. 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.

  8. 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.

  9. 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.

  10. The magnitude and direction movement in Thailand based on Global Positioning System (GPS)

    NASA Astrophysics Data System (ADS)

    Jamrus, Uthen; Deng, Hui

    2016-10-01

    In this research, we applied the Global Navigation Satellite System (GNSS) with Global Positioning System (GPS) to create new geodetic network, which is referred to ITRF2000. GPS observation data in 2010 and 2012 were used for network adjustment by Least Square Method (Minimally Constrained Adjustment and Fully Constrained Adjustment), then adjusted coordinates were used to determine updated magnitude and direction.

  11. Global attractivity and positive almost periodic solution of a single species population model

    NASA Astrophysics Data System (ADS)

    Yang, Xitao

    2007-12-01

    3/2-criterion is built, which guarantees the global attractivity of positive solution for equation having the form x'(t)=a(t)x(t)(1-L(t,xt)), where a(t)[greater-or-equal, slanted]0 and the linear functional L(t,[dot operator]) is positive. Moreover, when the equation is almost periodic, the similar conditions can also guarantee the existence and uniqueness of almost periodic solution that is globally attractive. Our results improve those in literature.

  12. 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…

  13. 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…

  14. Using the global positioning system to map disturbance patterns of forest harvesting machinery

    Treesearch

    T.P. McDonald; E.A. Carter; S.E. Taylor

    2002-01-01

    Abstract: A method was presented to transform sampled machine positional data obtained from a global positioning system (GPS) receiver into a two-dimensional raster map of number of passes as a function of location. The effect of three sources of error in the transformation process were investigated: path sampling rate (receiver sampling frequency);...

  15. 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.…

  16. Global Positioning System: Observations on Quarterly Reports from the Air Force

    DTIC Science & Technology

    2016-10-17

    Positioning System: Observations on Quarterly Reports from the Air Force The satellite-based Global Positioning System (GPS) provides positioning, navigation...3Pub. L. No. 114-92, § 1621 (2015). Page 2 GAO-17-162R GPS Quarterly Reports and short-term acquisition plans; and (2) observations for...to identify each quarterly report to distinguish between reports. In response to our initial observations on the first quarterly report, DOD and Air

  17. Comparison of Low-Cost Computer Algorithms for Global Positioning System Users.

    DTIC Science & Technology

    The Global Positioning System ( GPS ) is a navigation system which relies on range and range-rate measurements between satellites and the GPS -user in...order to determine his position and velocity. Using extensive support equipment, GPS is anticipated to achieve extremely accurate results. However... position estimates (dead-reckoning) for the first two approaches. The Kalman filter was modelled with fixed covariance matrices. The approaches were

  18. On global exponential stability of positive neural networks with time-varying delay.

    PubMed

    Hien, Le Van

    2017-03-01

    This paper presents a new result on the existence, uniqueness and global exponential stability of a positive equilibrium of positive neural networks in the presence of bounded time-varying delay. Based on some novel comparison techniques, a testable condition is derived to ensure that all the state trajectories of the system converge exponentially to a unique positive equilibrium. The effectiveness of the obtained results is illustrated by a numerical example.

  19. 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. PsycINFO Database Record (c) 2013 APA, all rights reserved

  20. [Positioning Ecuador in the global health agenda as a result of sector reform].

    PubMed

    Luna, Cristina; Emanuele, Carlos Andrés; Torre, Daniel De La

    2017-06-08

    Analyze strategies implemented by Ecuador's Ministry of Public Health (MPH) to position the country in the global health agenda during the period 2011-2015 as a result of health sector reform. Documentary review and interviews with stakeholders in national and international agencies with respect to positioning in the global health sphere during the study period. It was observed that the reform process produced a new framework to manage international health relations. The MPH implemented strategies and mechanisms to place national health priorities and interests on the global health agenda at bilateral, regional, and global levels. As a result, the country took a leadership role in certain processes and attained recognition at various international forums. The MPH reform process contributed to recognition and establishment of Ecuador's public policy priorities in the global health agenda through strategies such as giving importance to putting national priorities on the global health agenda, guiding the global health approach exercised by the highest health authority, developing technical capabilities and skills in the International Relations Office, and raising awareness in technical bodies.

  1. 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.

  2. Are the autism and positive schizotypy spectra diametrically opposed in local versus global processing?

    PubMed

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

    2010-08-01

    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 groups of students separated on autistic-like traits but matched on positive schizotypy traits, and two groups separated on positive schizotypy traits but matched on autistic-like traits (n = 20 per group). Consistent with their theory, higher levels of autistic-like traits were associated with faster identification of hidden figures, whereas higher levels of positive schizotypy traits were associated with slower identification.

  3. Cancer Evolution Is Associated with Pervasive Positive Selection on Globally Expressed Genes

    PubMed Central

    Ostrow, Sheli L.; Barshir, Ruth; DeGregori, James; Yeger-Lotem, Esti; Hershberg, Ruth

    2014-01-01

    Cancer is an evolutionary process in which cells acquire new transformative, proliferative and metastatic capabilities. A full understanding of cancer requires learning the dynamics of the cancer evolutionary process. We present here a large-scale analysis of the dynamics of this evolutionary process within tumors, with a focus on breast cancer. We show that the cancer evolutionary process differs greatly from organismal (germline) evolution. Organismal evolution is dominated by purifying selection (that removes mutations that are harmful to fitness). In contrast, in the cancer evolutionary process the dominance of purifying selection is much reduced, allowing for a much easier detection of the signals of positive selection (adaptation). We further show that, as a group, genes that are globally expressed across human tissues show a very strong signal of positive selection within tumors. Indeed, known cancer genes are enriched for global expression patterns. Yet, positive selection is prevalent even on globally expressed genes that have not yet been associated with cancer, suggesting that globally expressed genes are enriched for yet undiscovered cancer related functions. We find that the increased positive selection on globally expressed genes within tumors is not due to their expression in the tissue relevant to the cancer. Rather, such increased adaptation is likely due to globally expressed genes being enriched in important housekeeping and essential functions. Thus, our results suggest that tumor adaptation is most often mediated through somatic changes to those genes that are important for the most basic cellular functions. Together, our analysis reveals the uniqueness of the cancer evolutionary process and the particular importance of globally expressed genes in driving cancer initiation and progression. PMID:24603726

  4. 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.

  5. 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.

  6. The status of accurately locating forest inventory and analysis plots using the Global Positioning System

    Treesearch

    Michael Hoppus; Andrew Lister

    2007-01-01

    Historically, field crews used Global Positioning System (GPS) coordinates to establish and relocate plots, as well as document their general location. During the past 5 years, the increase in Geographic Information System (GIS) capabilities and in customer requests to use the spatial relationships between Forest Inventory and Analysis (FIA) plot data and other GIS...

  7. Causes and consequences of timing errors associated with global positioning system collar accelerometer activity monitors

    Treesearch

    Adam J. Gaylord; Dana M. Sanchez

    2014-01-01

    Direct behavioral observations of multiple free-ranging animals over long periods of time and large geographic areas is prohibitively difficult. However, recent improvements in technology, such as Global Positioning System (GPS) collars equipped with motion-sensitive activity monitors, create the potential to remotely monitor animal behavior. Accelerometer-equipped...

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

    USDA-ARS?s Scientific Manuscript database

    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...

  9. 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.

  10. 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...-Anh Trinh, Air Force Federal Register Liaison Officer. BILLING CODE 5001-10-P...

  11. 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.

  12. 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...

  13. 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.

  14. 76 FR 35858 - Global Positioning System Directorate (GPSD); Notice of Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-20

    ... Doc No: 2011-15185] DEPARTMENT OF DEFENSE Department of the Air Force Global Positioning System...) for Signals-in-Space (SiS) Documents (IS-GPS-200E, IS-GPS-705A, IS-GPS-800A). SUMMARY: The United States Air Force published a meeting notice on the Public Interface Control Group (ICWG) on June 2,...

  15. 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.

  16. 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…

  17. 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)

  18. Teaching High-Accuracy Global Positioning System to Undergraduates Using Online Processing Services

    ERIC Educational Resources Information Center

    Wang, Guoquan

    2013-01-01

    High-accuracy Global Positioning System (GPS) has become an important geoscientific tool used to measure ground motions associated with plate movements, glacial movements, volcanoes, active faults, landslides, subsidence, slow earthquake events, as well as large earthquakes. Complex calculations are required in order to achieve high-precision…

  19. 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…

  20. Global Positioning System Control/User Segments. Volume II. System Error Performance.

    DTIC Science & Technology

    RADIO NAVIGATION, *NAVIGATION SATELLITES, * POSITION FINDING, *NAVIGATION COMPUTERS, *IONOSPHERIC PROPAGATION, GLOBAL , EPHEMERIDES, TRADE OFF...ANALYSIS, SPACEBORNE, ERRORS, VELOCITY, SYSTEMS ENGINEERING, DIGITAL COMPUTERS, MEMORY DEVICES, TIME SIGNALS, SITE SELECTION, GROUND STATIONS, MOTION, MATHEMATICAL MODELS, ALGORITHMS, PERFORMANCE(ENGINEERING), USER NEEDS, S BAND, L BAND.

  1. The advanced OPLE for search and rescue. [OMEGA Position Location Experiment for global applications

    NASA Technical Reports Server (NTRS)

    Morakis, J. C.; Rupp, W.

    1973-01-01

    Recent technological advances have made it possible to develop an advanced OMEGA position location experiment for a global search and rescue application. This application generated some new problem areas such as the OMEGA lane ambiguity, random access, location accuracy, real time processing, and size and weight of the Search and Rescue Communication (SARCOM). This experiment will demonstrate the feasibility of instantaneous alarm and position location by using a relatively inexpensive, battery operated, three-pound package. This package can transmit the alarm and position through a synchronous satellite to a search and rescue station in less than three minutes.

  2. The advanced OPLE for search and rescue. [OMEGA Position Location Experiment for global applications

    NASA Technical Reports Server (NTRS)

    Morakis, J. C.; Rupp, W.

    1973-01-01

    Recent technological advances have made it possible to develop an advanced OMEGA position location experiment for a global search and rescue application. This application generated some new problem areas such as the OMEGA lane ambiguity, random access, location accuracy, real time processing, and size and weight of the Search and Rescue Communication (SARCOM). This experiment will demonstrate the feasibility of instantaneous alarm and position location by using a relatively inexpensive, battery operated, three-pound package. This package can transmit the alarm and position through a synchronous satellite to a search and rescue station in less than three minutes.

  3. 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

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

    PubMed

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

    2015-10-16

    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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. The Global Positioning System for Military Users: Current Modernization Plans and Alternatives

    DTIC Science & Technology

    2011-10-01

    Jammer 233-2. GPS Augmentation with the iGPS Program 26A-1. Structure of Signals Transmitted by GPS Satellites 34B-1. The Manpack and the Precision...MODERNIZATION PLANS AND ALTERNATIVES VIIB-8. Precision Lightweight GPS Receiver With and Without Antijam Antenna Retrofit 41B-9. iGPS Module, Including...Note: DoD = Department of Defense; GPS = Global Positioning System; INS = inertial navigation system; iGPS = High Integrity GPS. a. Includes 8 IIIC

  10. 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.

  11. The Global Rescue Alarm Net (GRAN) experiment. [application of OMEGA Position Location Experiment

    NASA Technical Reports Server (NTRS)

    Morakis, J. C.

    1972-01-01

    The OMEGA Position Location Experiment (OPLE) was performed in 1967 by the Goddard Space Flight Center in order to demonstrate a position location and data collection system. OMEGA navigation signals were received at a remote site and retransmitted via a synchronous satellite to a ground processing center where data collecting and position determination were performed. Recent technological advances have made it possible to develop an Advanced OPLE System towards a global search and rescue application. This application generated some new problem areas such as the OMEGA lane ambiguity, random access, location accuracy, real-time processing, and size and weight of the Search and Rescue Communications (SARCOM). This experiment demonstrates the feasibility of instantaneous alarm and position location by using a relatively inexpensive, battery operated, three-pound package.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. Global positive expectancies of the self and adolescents' substance use avoidance: testing a social influence mediational model.

    PubMed

    Carvajal, Scott C; Evans, Richard I; Nash, Susan G; Getz, J Greg

    2002-06-01

    Grounded in theories of global positive expectancies and social influences of behavior, this investigation posited a model in which global positive expectancies are related to substance use as mediated by attitudes, subjective norms, self-efficacy, and intentions. Using a cohort sample (n = 525), structural equation modeling was employed to test the hypothesized predictions of future substance use. The findings suggest that, relative to adolescents with lower global positive expectancies, adolescents with higher global positive expectancies use substances less frequently over time because of their protective attitudinal and control-oriented perceptions towards that behavior. Additionally, results from the current investigation also extend prior findings on the factor structure of global positive expectancies, suggesting these expectancies can be viewed as a second-order factor representing optimism and two components of hope-agency and pathways.

  19. 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.

  20. 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.

  1. Airborne Navigation Sensors Using The Global Positioning System (GPS) / Precise Positioning Service (PPS) for Area Navigation (RNAV) in Required Navigation Performance (RNP) Airspace; RNP-20 RNAV Through RNP-0.3 RNAV

    DTIC Science & Technology

    2010-02-11

    GLOBAL POSITIONING SYSTEM ( GPS ) I PRECISE POSITIONING SERVICE (PPS) FOR AREA NAVIGATION (RNA...Navigation Sensors Using The Global Positioning System ( GPS ) / Precise Positioning Service (PPS) For Area Navigation (RNAV) In Required Navigation...Rev. 8-98) Prescribed by ANSI Std Z39-18 Subject: MSO-C145, AIRBORNE NAVIGATION SENSORS USING THE GLOBAL POSITIONING SYSTEM ( GPS

  2. 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.

  3. 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].

  4. 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.

  5. 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.

  6. Local heterozygosity-fitness correlations with global positive effects on fitness in threespine stickleback.

    PubMed

    Lieutenant-Gosselin, Mélissa; Bernatchez, Louis

    2006-08-01

    The complex interactions between genetic diversity and evolution have important implications in many biological areas including conservation, speciation, and mate choice. A common way to study these interactions is to look at heterozygosity-fitness correlations (HFCs). Until recently, HFCs based on noncoding markers were believed to result primarily from global inbreeding effects. However, accumulating theoretical and empirical evidence shows that HFCs may often result from genes being linked to the markers used (local effect). Moreover, local effect HFCs could differ from global inbreeding effects in their direction and occurrence. Consequently, the investigation of the structure and consequences of local HFCs is emerging as a new important goal in evolutionary biology. In this study of a wild threespine stickleback (Gasterosteus aculeatus) population, we first tested the presence of significant positive or negative local effects of heterozygosity at 30 microsatellites loci on five fitness components: survival, mating success, territoriality, length, and body condition. Then, we evaluated the direction and shape of total impact of local HFCs, and estimated the magnitude of the impacts on fitness using regression coefficients and selection differentials. We found that multilocus heterozygosity was not a reliable estimator of individual inbreeding coefficient, which supported the relevance of single-locus based analyses. Highly significant and temporally stable local HFCs were observed. These were mainly positive, but negative effects of heterozygosity were also found. Strong and opposite effects of heterozygosity are probably present in many populations, but may be blurred in HFC analyses looking for global effects only. In this population, both negative and positive HFCs are apparently driving mate preference by females, which is likely to contribute to the maintenance of both additive and nonadditive genetic variance.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  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. Global geodesic acoustic mode in a tokamak with positive magnetic shear and a monotonic temperature profile

    NASA Astrophysics Data System (ADS)

    Ilgisonis, V. I.; Khalzov, I. V.; Lakhin, V. P.; Smolyakov, A. I.; Sorokina, E. A.

    2014-03-01

    The analytical solution for global geodesic acoustic modes (GGAMs) in a tokamak with a positive magnetic shear profile and a monotonic temperature profile is found in the framework of magnetohydrodynamic theory. The axisymmetric eigenvalue problem for perturbed pressure and electrostatic potential is formulated as a recurrent set of equations for poloidal Fourier harmonics. The integral condition for the existence of GGAMs is obtained. It is shown that the traditional paradigm of having a off-axis maximum of the local geodesic acoustic frequency is not necessary for the existence of GGAMs; a representative example is designed.

  13. 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.

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

    NASA Astrophysics Data System (ADS)

    Bar-Sever, Y. E.

    1995-11-01

    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.

  15. Cost analysis of Navy acquisition alternatives for the NAVSTAR Global Positioning System

    NASA Astrophysics Data System (ADS)

    Darcy, T. F.; Smith, G. P.

    1982-12-01

    This research analyzes the life cycle cost (LCC) of the Navy's current and two hypothetical procurement alternatives for NAVSTAR Global Positioning System (GPS) user equipment. Costs are derived by the ARINC Research Corporation ACBEN cost estimating system. Data presentation is in a comparative format describing individual alternative LCC and differential costs between alternatives. Sensitivity analysis explores the impact receiver-processor unit (RPU) first unit production cost has on individual alternative LCC, as well as cost differentials between each alternative. Several benefits are discussed that might provide sufficient cost savings and/or system effectiveness improvements to warrant a procurement strategy other than the existing proposal.

  16. 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.

  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 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.

  19. 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.

  20. The use of the Global Positioning System for ballistic missile tracking

    NASA Astrophysics Data System (ADS)

    Hoefener, Carl E.; Wartenberg, Martin R.

    During test and evaluation of ballistic missiles there is a requirement for precision Time, Space, Position, and Information (TSPI) determination. Ballistic missiles must be tracked during test for range safety purposes so that an errant missile may be destroyed, and the missile trajectory can be precisely determined in order to evaluate the missile guidance system. In the past, the tracking accuracies obtained from instrumentation radars for TSPI was not sufficient, particularly for trajectory determination. Radars may also be problematic for range safety if the weapons are launched far at sea or more than one must be tracked simultaneously. For metric tracking or precision trajectory determination, a Global Positioning System (GPS) translator tracking system can record the entire mission for postflight analysis, and the mission may be replayed as often as required allowing tracking filter optimization.

  1. 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

  2. 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.

  3. 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.

  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.

  5. 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.

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

    DOE PAGES

    Luo, Yiyong; Lu, Jian; Liu, Fukai; ...

    2016-02-04

    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 (CESM) and applying an overriding technique to its ocean component Parallel Ocean Program version 2 (POP2), this study investigates the similarity and difference 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, the Bjerknes feedback is the leading mechanism in producing the anomalous cooling over the eastern tropics in both cases.more » Some differences are also found, including that the cooling effect of the vertical advection over the eastern tropical Indian Ocean is dominated by the anomalous vertical velocity during the pIOD while it is dominated by the anomalous upper-ocean stratification under global warming. Lastly, these findings above are further examined with an analysis of the mixed layer heat budget.« less

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

    SciTech Connect

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

    2016-02-04

    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 (CESM) and applying an overriding technique to its ocean component Parallel Ocean Program version 2 (POP2), this study investigates the similarity and difference 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, the Bjerknes feedback is the leading mechanism in producing the anomalous cooling over the eastern tropics in both cases. Some differences are also found, including that the cooling effect of the vertical advection over the eastern tropical Indian Ocean is dominated by the anomalous vertical velocity during the pIOD while it is dominated by the anomalous upper-ocean stratification under global warming. Lastly, these findings above are further examined with an analysis of the mixed layer heat budget.

  8. Assessment of wearable global positioning system units for physical activity research.

    PubMed

    Wieters, Kathleen Meghan; Kim, Jun-Hyun; Lee, Chanam

    2012-09-01

    Responding to the growing interest in the environmental influences on physical activity, and the concerns about the limitations of self-report data, this study evaluates Global Positioning System (GPS) units for measuring outdoor physical activity. Four GPS models were selected to test their accuracy related to adherence to an actual route walked, variations based on position of unit on user's body, and variations against a known geodetic point. A qualitative assessment was performed using the following criteria: a) battery life, b) memory capacity, c) initial satellite signal acquisition time, d) ease of data transfer to other programs, e) wearability, f) ease of operation, g) suitability for specific study populations, and h) price. The Garmin Forerunner provided the most accurate data for data points collected along a known route. Comparisons based on different body placement of units showed some variations. GlobalSat reported battery life of 24 hours, compared with 9-15 hours for the other units. The static test using ANOVA showed that the Garmin Foretrex's data points compared with a geodetic point was significantly more accurate than the other 3 models. GPS units appear promising as a tool to capture objective data on outdoor physical activities.

  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. 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.

  11. Global Positioning System phase fluctuations and ultraviolet images from the Polar satellite

    NASA Astrophysics Data System (ADS)

    Aarons, J.; Lin, B.; Mendillo, M.; Liou, K.; Codrescu, M.

    2000-03-01

    In a study designed to determine the temporal development of ionospheric irregularities in the auroral region in magnetic storm periods, different types of simultaneous observations were compared for the storms of January 10, April 10-11, and May 15, 1997. The data sets consisted of ultraviolet images (UVI) from the Polar satellite, phase fluctuations and total electron content (TEC) from Global Positioning Systems (GPS) recordings at a large number of sites, magnetometer observations and hemispheric power precipitation. The large-scale global or macroscale picture of the magnetic storm showed the importance of universal time in the development of irregularities. The hemispheric total power picture and the global indices such as Kp show this macroscale picture of the entire storm period. However, individual sites show differences in localized magnetic field variations and the development of irregularities; this we term the microscale. The storms of January 10 and May 15 show the importance of local magnetic time and local magnetic variations at the sites, while the storm of April 10-11 was dominated by the UT storm development. During the intense activity of the storms, total electron content shows minute-by-minute increases with the satellite moving to positions 6 km apart in the minute. The structured precipitation either directly produces irregularities or indirectly sets instability conditions for irregularity development in the auroral region. Good correlation was established for the three storms between UVI intensity and phase fluctuation development. The UVI Lyman-Birge-Hopfield-long (170 nm) emission is sensitive to 100-200 km precipitation. Phase fluctuation development undoubtedly arises from perturbations in the F region as well. Topside and bottomside soundings have shown the high occurrence of spread-F in the auroral region. The comparison of the data sets from these storms and from other studies indicates that the creation of irregularities develops

  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. Positive symptoms are associated with clinicians' global impression in treatment-resistant schizophrenia.

    PubMed

    Lee, Jimmy; Fervaha, Gagan; Takeuchi, Hiroyoshi; Powell, Valerie; Remington, Gary

    2015-06-01

    Previous investigations on the relationship between global rating measures and symptoms have not considered the additional role of functioning. In this naturalistic study, we examined the relationship between symptom domains and functioning on Clinical Global Impression scales for severity (CGI-S) and improvement (CGI-I) in a sample of patients with schizophrenia assessed to be treatment resistant. Participants were patients with a diagnosis of schizophrenia or schizoaffective disorder who failed 2 prior antipsychotic trials and were considered candidates for clozapine. They were assessed on the 18-item Brief Psychiatric rating Scale (BPRS), Social Occupational Functioning Assessment Scale (SOFAS), and CGI-S at baseline. A subset of patients was followed up at 6 weeks after initiation of clozapine and assessed on the CGI-I. The independent effects of symptom domains and functioning on the CGI scales were examined via multivariate regression models. Brief Psychiatric rating Scale positive factor (P < 0.001) and SOFAS (P < 0.001) scores were significant determinants of CGI-S at baseline. Multivariate models suggested that relative change measures had a better fit for the CGI-I compared to absolute change measures (R = 0.72 vs R = 0.61, respectively). Improvements in BPRS positive (P < 0.001) and affect (P = 0.002) factors and SOFAS (P = 0.030) scores were significant determinants of CGI-I. Ratings of 1 and 2 on the CGI-I corresponded to a mean relative change in the BPRS total of 65% and 41%, respectively. Positive symptoms were a key determinant of clinicians' impression of severity and improvement in this study. Although psychosocial functioning played a large part in determining severity, it was not as significant in the assessment of improvement.

  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. 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...

  16. 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.

  17. Movement and physiological match demands of elite rugby league using portable global positioning systems.

    PubMed

    Waldron, Mark; Twist, Craig; Highton, Jamie; Worsfold, Paul; Daniels, Matthew

    2011-08-01

    Twelve elite players from an English Super League club consented to participate in the present study using portable global positioning system (GPS) devices to assess position-specific demands. Distances covered at low-intensity running, moderate-intensity running, high-intensity running, very high-intensity running, and total distance were significantly (P < 0.05) lower in forwards compared with outside backs and adjustables. Metres per minute was higher in adjustables and forwards, owing to higher values for relative distance in medium-intensity running and a rise in high-intensity running from previous absolute values. Sprint distance, sprint frequency, and peak speed were higher in outside backs than both adjustables and forwards. A moderate, significant correlation (r = 0.62, P = 0.001) was apparent between session ratings of perceived exertion and summated heart rate. Results support the requirement for position-specific conditioning and provide preliminary evidence for the use of session ratings of perceived exertion as a measure of match load.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. A protocol for geographically randomized snail surveys in schistosomiasis fieldwork using the global positioning system.

    PubMed

    Seto, E; Liang, S; Qiu, D; Gu, X; Spear, R C

    2001-01-01

    A protocol was created for performing geographically randomized snail surveys for schistosomiasis research using the global positioning system (GPS). This protocol differs from traditional surveys in its ability to accurately map and measure the spatial distribution of snail habitat. The protocol was used to map irrigation ditches, the primary habitat for Oncomelania hupensis, in two residence areas in Sichuan Province, China. From the 7,450 meters of mapped ditches, snail surveys were performed at 203 random sites along the ditch network. Of these, 116 (57.1%) sites had snails. The total number of living snails captured was 2,014, resulting in an average snail density of 0.27 snails per linear meter of potential habitat.

  5. 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.

  6. 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

    2017-07-01

    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.

  7. 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.

  8. 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,

  9. 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.

  10. 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.

  11. 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.

  12. 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..

  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. 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.

  15. Global Positioning System - A Modification to the Baseline Satellite Constellation for Improved Geometric Performance.

    DTIC Science & Technology

    1984-12-01

    84D-4 DTC Approved for public releas; distribution unlimitedD AFI T/G/ENG/84D-4 GLOBAL POSITIONING SYSTEM - A MODIFICATION TO THE BASELINE STELLITE ...TO 401 400 IF(MBS.LT.4) GO TO 479 401 BOX-10. IFR(ISCHP. EQ. I) GO TO 405 CALL TRAT (HSS,KCN,KXX) GO TO 410 405 KOT-IK IF(LOC.EQ.2.OR.LOC.EQ.3...KOTNSS CALL TAILL (KOT,KCat,K0XX) 410 00 430 M- 1, KCO 00 415 LPQ.LPN,4 IS IC(LPQ ).IOSMAI) 415 CONT I ME CALL IU.LNE (USJ, I sI C,I.ULtI) IFQ(UE1.GT.9OX

  16. Intercontinental time and frequency transfer using a global positioning system timing receiver

    NASA Technical Reports Server (NTRS)

    Clements, P. A.

    1983-01-01

    The DSN has a requirement to maintain knowledge of the frequency offset between DSN stations with 3 x 10 to the minus 13th power and time offset within 10 microseconds. It is further anticipated that in the 1987-1990 era the requirement for knowledge of time offset between DSN stations will be less than 10 nanoseconds. JPL is using the Global Positioning System (GPS) Space Vehicles, as a development project, to transfer time and frequency over intercontinental distances between stations of the DSN and between the DSN and other agencies. JPL has installed GPS timing receivers at its tracking station near Barstow, California, and at its tracking station near Madrid, Spain. The details of the experiment and the data are reported. There is a discussion of the ultimate capabilities of these techniques for meeting the functional requirements of the DSN.

  17. Monitoring mobility in older adults using global positioning system (GPS) watches and accelerometers: a feasibility study.

    PubMed

    Webber, Sandra C; Porter, Michelle M

    2009-10-01

    This exploratory study examined the feasibility of using Garmin global positioning system (GPS) watches and ActiGraph accelerometers to monitor walking and other aspects of community mobility in older adults. After accuracy at slow walking speeds was initially determined, 20 older adults (74.4 +/- 4.2 yr) wore the devices for 1 day. Steps, distances, and speeds (on foot and in vehicle) were determined. GPS data acquisition varied from 43 min to over 12 hr, with 55% of participants having more than 8 hr between initial and final data-collection points. When GPS data were acquired without interruptions, detailed mobility information was obtained regarding the timing, distances covered, and speeds reached during trips away from home. Although GPS and accelerometry technology offer promise for monitoring community mobility patterns, new GPS solutions are required that allow for data collection over an extended period of time between indoor and outdoor environments.

  18. Ionospheric total-electron-content estimation for single-frequency Global-positioning-system receivers

    SciTech Connect

    Smith, C.A.

    1987-01-01

    The ionosphere delays transmissions from the Global Positioning System (GPS), as well as those from other satellite systems. At the GPS frequencies (L-Band), this delay is directly proportional to the total ionospheric electron content (TEC) along the line-of-sight to the satellite. Classified receivers have access to 2 frequencies to allow them to measure this delay through the difference in the ionospheric effect at the 2 frequencies, but commercial, single-frequency receivers have had no direct method for estimating the ionospheric delay; they have had to rely on a TEC prediction. Two methods are described for single-frequency GPS receivers to estimate the ionospheric TEC directly. These methods take advantage of the dispersive nature of the ionosphere at L-Band frequencies, which causes a phase advance of the carrier that is opposite to the group delay of the GPS code and data.

  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. 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.

  1. 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.

  2. 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.

  3. Integrated Inertial Navigation System/Global Positioning System (INS/GPS) for automatic space return vehicle

    NASA Astrophysics Data System (ADS)

    Braden, Kevin; Browning, Clint; Gelderloos, Hendrik

    A digital global navigation and communications system that automatically returns a space vehicle from orbit to a precision touchdown/landing is described. It is demonstrated that a capsule or lifting body manned return vehicle (MRV) with integrated INS/GPS (inertial navigation system/Global Positioning System) provides a highly autonomous and automatic deorbit, entry, and precision landing capability. Simulation results are used to demonstrate automatic MRV landing feasibility using absolute GPS for a vertically landing capsule vehicle and the feasibility of using integrated differential GPS/INS to provide the accuracy for a lifting body to perform a safe runway landing without needing TACAN (tactical air navigation) or microwave landing system (MLS) navigational aids. An advanced system using differential GPS/INS will be tested with the NASA Langley transport research vehicle during approach and landing flight phases in October 1990. It is expected that these proof-of-concept flight tests will provide an extensive database on GPS/INS system accuracies and will demonstrate a lower cost alternative to TACAN, DME (distance measuring equipment), and MLS navigation aids.

  4. 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.

  5. Repigmentation in vitiligo: position paper of the Vitiligo Global Issues Consensus Conference.

    PubMed

    Gan, Emily Y; Eleftheriadou, Viktoria; Esmat, Samia; Hamzavi, Iltefat; Passeron, Thierry; Böhm, Markus; Anbar, Tag; Goh, Boon Kee; Lan, Cheng-Che E; Lui, Harvey; Ramam, M; Raboobee, Noufal; Katayama, Ichiro; Suzuki, Tamio; Parsad, Davinder; Seth, Vaneeta; Lim, Henry W; van Geel, Nanja; Mulekar, Sanjeev; Harris, John; Wittal, Richard; Benzekri, Laila; Gauthier, Yvon; Kumarasinghe, Prasad; Thng, Steven T G; Silva de Castro, Caio Cesar; Abdallah, Marwa; Vrijman, Charlotte; Bekkenk, Marcel; Seneschal, Julien; Pandya, Amit G; Ezzedine, Khaled; Picardo, Mauro; Taïeb, Alain

    2017-01-01

    The Vitiligo Global Issues Consensus Conference (VGICC), through an international e-Delphi consensus, concluded that 'repigmentation' and 'maintenance of gained repigmentation' are essential core outcome measures in future vitiligo trials. This VGICC position paper addresses these core topics in two sections and includes an atlas depicting vitiligo repigmentation patterns and color match. The first section delineates mechanisms and characteristics of vitiligo repigmentation, and the second section summarizes the outcomes of international meeting discussions and two e-surveys on vitiligo repigmentation, which had been carried out over 3 yr. Treatment is defined as successful if repigmentation exceeds 80% and at least 80% of the gained repigmentation is maintained for over 6 months. No agreement was found on the best outcome measure for assessing target or global repigmentation, therefore highlighting the limitations of e-surveys in addressing clinical measurements. Until there is a clear consensus, existing tools should be selected according to the specific needs of each study. A workshop will be conducted to address the remaining issues so as to achieve a consensus.

  6. Global sensitivity analysis of the dispersion maximum position of the PCFs with circular holes

    NASA Astrophysics Data System (ADS)

    Guryev, Igor; Sukhoivanov, Igor; Andrade Lucio, Jose A.; Vargas Rodrigues, Everardo; Shulika, Oleksiy; Mata Chavez, Ruth I.; Baca Montero, Eric R.

    2015-08-01

    Microstructured fibers have recently become popular due to their numerous applications for fiber lasers,1 super-continuum generationi2 and pulse reshaping.3 One of the most important properties of such fibers that is taken into account is its dispersion. Fine tuning of the dispersion (i.e. dispersion management) is one of the crucial peculiarities of the photonic crystal fibers (PCFs)4 that are particular case of the microstructured fibers. During last years, there have been presented various designs of the PCFs possessing specially-designed dispersion shapes. 5-7 However, no universal technique exists which would allow tuning the PCF dispersion without using optimization methods. In our work, we investigate the sensitivity of the PCF dispersion as respect to variation of its basic parameters. This knowledge allows fine-tuning the position of local maximum of the PCF dispersion while maintaining other properties unchanged. The work is organized as follows. In the first section we discuss the dispersion computation method that is suitable for the global sensitivity analysis. The second section presents the global sensitivity analysis for this specific case. We also discuss there possible selection of the variable parameters.

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. Using the Global Positioning System to monitor dynamic ground deformation networks on potentially active landslides

    NASA Astrophysics Data System (ADS)

    Moss, Jane L.

    The Global Positioning System (GPS) has many advantages over conventional surveying for landslide disaster prevention and mitigation. Once an initial baseline network of ground markers has been positioned, the re-occupation of survey stations determines ground deformation. This verifies both the boundary of the landslide block and ground surface changes. These changes may take the form of either slow to moderate creep, or massive structural failure. Creep may occur as a precursor to slope failure, either within (i) fresh slopes that do not show any evidence of past collapse, (ii) the existing active landslides and (iii) areas adjacent to existing collapses. Networks are measured using rapid static GPS. The method, which enables many survey stations to be measured in a short time, provides a quick means for determining the three-dimensional map of the ground surface (of the landslide). A study in Gran Canaria, Canary Islands, established an initial baseline network within the Barranco de Tirajana, a basin on Gran Canaria that contains evidence of both ancient and recent landslides. Reoccupation of the network using rapid static GPS revealed a field accuracy of approximately 10 mm; the data indicated that the most recent landslide is currently stable.

  12. 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.

  13. 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

    2013-06-06

    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.

  14. 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

  15. 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.

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

    PubMed

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

    2010-07-27

    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.

  17. Halo orbit dynamics and properties for a lunar global positioning system design

    NASA Astrophysics Data System (ADS)

    Circi, Christian; Romagnoli, Daniele; Fumenti, Federico

    2014-08-01

    In this paper, the use of north and south families of halo orbits, around the L1 and L2 collinear libration points of the Earth-Moon system, to realize a lunar global positioning system (LGPS) is proposed. The computation of the reference trajectories and the required station-keeping manoeuvres with the associated ΔV are described, as well as different configurations for the satellites' constellation. The combination of the north and south families of halo orbits results in an X-shaped configuration allowing optimal performances. A visibility study, from different locations on the lunar surface, has been performed together with a performance analysis in terms of availability of the LGPS signal and quality of the position solution, resulting in a candidate architecture able to guarantee the availability of the LGPS service at the scientifically interesting lunar poles. In addition, the proposed constellations are also interesting from a connection point of view, assuring continuous communication capabilities between the Earth and every location on the surface of the Moon, as well as between any of the points on the ground.

  18. 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.

  19. Three-Dimensional Geodetic Control by Interferometry with GPS (Global Positioning System): Processing of GPS Phase Observables.

    DTIC Science & Technology

    1985-04-23

    8217 geodetic networks; three, dimensional geodesy, satellite geodesy, NAVSTAR Global Positioning System,’ GPS , interferometry 20. ABSTRACT (Continue on reverse...8217 - - .. . . . . . . . . . . . . . -t INTRODUCTION GPS interferometry is a method by which three-dimensional relative-position vectors between observing stations can be

  20. Gray matter volume correlates of global positive alcohol expectancy in non-dependent adult drinkers

    PubMed Central

    Ide, Jaime S.; Zhang, Sheng; Hu, Sien; Matuskey, David; Bednarski, Sarah R.; Erdman, Emily; Farr, Olivia M.; Li, Chiang-shan R.

    2013-01-01

    Alcohol use and misuse is known to involve structural brain changes. Numerous imaging studies have examined changes in gray matter (GM) volumes in dependent drinkers, but there is little information on whether non-dependent drinking is associated with structural changes and whether these changes are related to psychological factors – such as alcohol expectancy – that influence drinking behavior. We used voxel based morphometry (VBM) to examine whether the global positive scale of alcohol expectancy, as measured by the Alcohol Expectancy Questionnaire AEQ-3, is associated with specific structural markers and whether such markers are associated with drinking behavior in 113 adult non-dependent drinkers (66 women). Alcohol expectancy is positively correlated with GM volume of left precentrral gyrus (PCG) in men and women combined and bilateral superior frontal gyri (SFG) in women, and negatively correlated with GM volume of the right ventral putamen in men. Furthermore, mediation analyses showed that the GM volume of PCG mediate the correlation of alcohol expectancy and the average number of drinks consumed per occasion and monthly total number of drinks in the past year. When recent drinking was directly accounted for in multiple regressions, GM volume of bilateral dorsolateral prefrontal cortices (DLPFC) correlated positively with alcohol expectancy in the combined sample. To our knowledge, these results are the first to identify the structural brain correlates of alcohol expectancy and its mediation of drinking behaviors. These findings suggest that more studies are needed to investigate increased GM volume in the frontal cortices as a neural correlate of alcohol expectancy. PMID:23461484

  1. Field testing a global positioning system (GPS) collar on a Japanese monkey: reliability of automatic GPS positioning in a Japanese forest.

    PubMed

    Sprague, David S; Kabaya, Hajime; Hagihara, Ko

    2004-04-01

    A global positioning system (GPS) collar recorded the locations of an adult female Japanese macaque over a 9-day period in a habitat with mixed suburban and rural land-uses in Chiba Prefecture, Japan. The GPS device acquired positions even in forested areas. The GPS data located the female mostly in forested areas, although the female had ranged through a habitat with inter-mingled fields, orchards, quarries, and residential areas. However, the GPS position acquisition rate was low compared to studies carried out on North American mammals. The GPS fixed a position in 20% of positioning attempts. When the collared female was tracked by radio-telemetry, almost all failures of the GPS to fix a position occurred in forest.

  2. Positioning.

    ERIC Educational Resources Information Center

    Conone, Ruth M.

    The key to positioning is the creation of a clear benefit image in the consumer's mind. One positioning strategy is creating in the prospect's mind a position that takes into consideration the company's or agency's strengths and weaknesses as well as those of its competitors. Another strategy is to gain entry into a position ladder owned by…

  3. 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.

  4. 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.

  5. Energetic Particle Data From the Global Positioning System Constellation: GPS ENERGETIC PARTICLE DATA

    DOE PAGES

    Morley, S. K.; Sullivan, J. P.; Carver, M. R.; ...

    2017-02-01

    Since 2000, Los Alamos National Laboratory (LANL) Combined X-ray and Dosimeter (CXD) and Burst Detector Dosimeter for Block II-R (BDD-IIR) instruments have been fielded on Global Positioning System (GPS) satellites. Today, 21 of the 31 operational GPS satellites are equipped with a CXD detector and a further 2 carry a BDD-IIR. Each of these instruments measures a wide range of energetic electrons and protons. These data have now been publicly released under the terms of the Executive Order for Coordinating Efforts to Prepare the Nation for Space Weather Events. The specific goal of releasing space weather data from the GPSmore » satellites is to enable broad scientific community engagement in enhancing space weather model validation and improvements in space weather forecasting and situational awareness. The time period covered by this data release is approximately 16 years, which corresponds to more than 167 satellite years of data. As a result, the large number of GPS satellites, distributed over six orbital planes, will provide important context for ongoing and historical science missions, as well as enabling new types of research not previously possible.« less

  6. Global Positioning System Energetic Particle Data: The Next Space Weather Data Revolution

    NASA Technical Reports Server (NTRS)

    Knipp, Delores J.; Giles, Barbara L.

    2016-01-01

    The Global Positioning System (GPS) has revolutionized the process of getting from point A to point Band so much more. A large fraction of the worlds population relies on GPS (and its counterparts from other nations) for precision timing, location, and navigation. Most GPS users are unaware that the spacecraft providing the signals they rely on are operating in a very harsh space environment the radiation belts where energetic particles trapped in Earths magnetic field dash about at nearly the speed of light. These subatomic particles relentlessly pummel GPS satellites. So by design, every GPS satellite and its sensors are radiation hardened. Each spacecraft carries particle detectors that provide health and status data to system operators. Although these data reveal much about the state of the space radiation environment, heretofore they have been available only to system operators and supporting scientists. Research scientists have long sought a policy shift to allow more general access. With the release of the National Space Weather Strategy and Action Plan organized by the White House Office of Science Technology Policy (OSTP) a sample of these data have been made available to space weather researchers. Los Alamos National Laboratory (LANL) and the National Center for Environmental Information released a months worth of GPS energetic particle data from an interval of heightened space weather activity in early 2014 with the hope of stimulating integration of these data sets into the research arena. Even before the public data release GPS support scientists from LANL showed the extraordinary promise of these data.

  7. 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.

  8. 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.

  9. 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.

  10. 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. 

  11. 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 MMSis 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.

  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. Distributions of positive correlations in sectoral value added growth in the global economic network*

    NASA Astrophysics Data System (ADS)

    Maluck, Julian; Donner, Reik V.

    2017-02-01

    International trade has grown considerably during the process of globalization. Complex supply chains for the production of goods have resulted in an increasingly connected International Trade Network (ITN). Traditionally, direct trade relations between industries have been regarded as mediators of supply and demand spillovers. With increasing network connectivity the question arises if higher-order relations become more important in explaining a national sector's susceptibility to supply and demand changes of its trading partner. In this study we address this question by investigating empirically to what extent the topological properties of the ITN provide information about positive correlations in the production of two industry sectors. We observe that although direct trade relations between industries serve as important indicators for correlations in the industries' value added growth, opportunities of substitution for required production inputs as well as second-order trade relations cannot be neglected. Our results contribute to a better understanding of the relation between trade and economic productivity and can serve as a basis for the improvement of crisis spreading models that evaluate contagion threats in the case of a node's failure in the ITN.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Mobile very long baseline interferometry and Global Positioning System measurement of vertical crustal motion

    NASA Technical Reports Server (NTRS)

    Kroger, Peter M.; Davidson, John M.; Gardner, Elaine C.

    1986-01-01

    Mobile Very Long Base Interferometry (VLBI) and Global Positioning System (GPS) geodetic measurements have many error sources in common. Calibration of the effects of water vapor on signal transmission through the atmosphere, however, remains the primary limitation to the accuracy of vertical crustal motion measurements made by either technique. The two primary methods of water vapor calibration currently in use for mobile VLBI baseline measurements were evaluated: radiometric measurements of the sky brightness near the 22 GHz emission line of free water molecules and surface meteorological measurements used as input to an atmospheric model. Based upon a limited set of 9 baselines, it is shown that calibrating VLBI data with water vapor radiometer measurements provides a significantly better fit to the theoretical decay model than calibrating the same data with surface meteorological measurements. The effect of estimating a systematic error in the surface meteorological calibration is shown to improve the consistency of the vertical baseline components obtained by the two calibration methods. A detailed error model for the vertical baseline components obtained indicates current mobile VLBI technology should allow accuracies of order 3 cm with WVR calibration and 10 cm when surface meteorological calibration is used.

  19. 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.

  20. Global Positioning System-Based Stimulation for Robo-Pigeons in Open Space

    PubMed Central

    Yang, Junqing; Huai, Ruituo; Wang, Hui; Li, Wenyuan; Wang, Zhigong; Sui, Meie; Su, Xuecheng

    2017-01-01

    An evaluation method is described that will enable researchers to study fight control characteristics of robo-pigeons in fully open space. It is not limited by the experimental environment and overcomes environmental interference with flight control in small experimental spaces using a compact system. The system consists of two components: a global positioning system (GPS)-based stimulator with dimensions of 38 mm × 26 mm × 8 mm and a weight of 18 g that can easily be carried by a pigeon as a backpack and a PC-based program developed in Virtual C++. The GPS-based stimulator generates variable stimulation and automatically records the GPS data and stimulus parameters. The PC-based program analyzes the recorded data and displays the flight trajectory of the tested robo-pigeon on a digital map. This method enables quick and clear evaluation of the flight control characteristics of a robo-pigeon in open space based on its visual trajectory, as well as further optimization of the microelectric stimulation parameters to improve the design of robo-pigeons. The functional effectiveness of the method was investigated and verified by performing flight control experiments using a robo-pigeon in open space. PMID:28855869

  1. 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.

  2. 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.

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

    NASA Astrophysics Data System (ADS)

    Larsen, Shawn; Reilinger, Robert

    1992-06-01

    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.

  4. Global Positioning System Energetic Particle Data: The Next Space Weather Data Revolution

    NASA Technical Reports Server (NTRS)

    Knipp, Delores J.; Giles, Barbara L.

    2016-01-01

    The Global Positioning System (GPS) has revolutionized the process of getting from point A to point Band so much more. A large fraction of the worlds population relies on GPS (and its counterparts from other nations) for precision timing, location, and navigation. Most GPS users are unaware that the spacecraft providing the signals they rely on are operating in a very harsh space environment the radiation belts where energetic particles trapped in Earths magnetic field dash about at nearly the speed of light. These subatomic particles relentlessly pummel GPS satellites. So by design, every GPS satellite and its sensors are radiation hardened. Each spacecraft carries particle detectors that provide health and status data to system operators. Although these data reveal much about the state of the space radiation environment, heretofore they have been available only to system operators and supporting scientists. Research scientists have long sought a policy shift to allow more general access. With the release of the National Space Weather Strategy and Action Plan organized by the White House Office of Science Technology Policy (OSTP) a sample of these data have been made available to space weather researchers. Los Alamos National Laboratory (LANL) and the National Center for Environmental Information released a months worth of GPS energetic particle data from an interval of heightened space weather activity in early 2014 with the hope of stimulating integration of these data sets into the research arena. Even before the public data release GPS support scientists from LANL showed the extraordinary promise of these data.

  5. 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.

  6. 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.

  7. Canada's global position in life expectancy: a longitudinal comparison with the healthiest countries in the world.

    PubMed

    Fang, Raymond; Millar, John S

    2009-01-01

    To assess the global position of Canadian life expectancy and to determine the areas of greatest negative impact on life expectancy. Using retrospective data on life expectancy at birth (LE(0) and age-standardized mortality rates, Canada was compared with 13 other countries with the longest LE(0). Linear regression models were used to produce trends and projections of LE(0) until 2010. Canadian women and men currently rank 8th and 5th, respectively, in LE(0) among the 14 nations. Canada has one of the smallest annual LE(0) improvement rates among the countries studied. Canadian women progressed significantly slower than nine countries and Canadian men progressed slower than five. Women are improving at only half the rate of men due to narrowing gaps in most mortality risks--mostly for cardiovascular diseases, lung cancer and injury. These trends lowered projected LE(0) ranks of Canadians, especially for women, for 2010. LE(0) of Canadians is slipping relative to most of the other 13 countries, and more so for women than men. This phenomenon is explained by historically higher mortality rates from ischemic heart disease, cancer and respiratory system disease for all Canadians, coupled with recently lower improvement rates in most mortality risks for Canadian women and in cancers and diabetes for Canadian men. Improving the health and wellness of Canadians, particularly women, demands a priority focus on enhanced chronic disease detection and management as well as strategies to reduce obesity and tobacco use by addressing the determinants of these behavioural risk factors.

  8. Global Failure Criteria for Positive/Electrolyte/Negative Structure of Planar Solid Oxide Fuel Cell

    SciTech Connect

    Liu, Wenning N.; Sun, Xin; Khaleel, Mohammad A.; Qu, Jianmin

    2009-07-15

    Due to mismatch of the coefficients of thermal expansion of various layers in the positive/electrolyte/negative (PEN) structures of solid oxide fuel cells (SOFC), thermal stresses and warpage on the PEN are unavoidable due to the temperature changes from the stress-free sintering temperature to room temperature during the PEN manufacturing process. In the meantime, additional mechanical stresses will also be created by mechanical flattening during the stack assembly process. In order to ensure the structural integrity of the cell and stack of SOFC, it is necessary to develop failure criteria for SOFC PEN structures based on the initial flaws occurred during cell sintering and stack assembly. In this paper, the global relationship between the critical energy release rate and critical curvature and maximum displacement of the warped cells caused by the temperature changes as well as mechanical flattening process is established so that possible failure of SOFC PEN structures may be predicted deterministically by the measurement of the curvature and displacement of the warped cells.

  9. Mobile very long baseline interferometry and Global Positioning System measurement of vertical crustal motion

    NASA Technical Reports Server (NTRS)

    Kroger, Peter M.; Davidson, John M.; Gardner, Elaine C.

    1986-01-01

    Mobile Very Long Base Interferometry (VLBI) and Global Positioning System (GPS) geodetic measurements have many error sources in common. Calibration of the effects of water vapor on signal transmission through the atmosphere, however, remains the primary limitation to the accuracy of vertical crustal motion measurements made by either technique. The two primary methods of water vapor calibration currently in use for mobile VLBI baseline measurements were evaluated: radiometric measurements of the sky brightness near the 22 GHz emission line of free water molecules and surface meteorological measurements used as input to an atmospheric model. Based upon a limited set of 9 baselines, it is shown that calibrating VLBI data with water vapor radiometer measurements provides a significantly better fit to the theoretical decay model than calibrating the same data with surface meteorological measurements. The effect of estimating a systematic error in the surface meteorological calibration is shown to improve the consistency of the vertical baseline components obtained by the two calibration methods. A detailed error model for the vertical baseline components obtained indicates current mobile VLBI technology should allow accuracies of order 3 cm with WVR calibration and 10 cm when surface meteorological calibration is used.

  10. 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.

  11. Vulnerabilities of the Global Positioning System and the Impact on the Iron Triad: The AWACS, JSTARS, and Rivet Joint Fleets

    DTIC Science & Technology

    2010-06-11

    Aviation Administration FANS Future Air Navigation System GAO Government Accountability Office GBAS Ground Based Augmentation System GLS GNSS Landing...System GNSS Global Navigation Satellite System GPS Global Positioning System ICAO International Civil Aviation Organization INU Inertial...Systems ( GNSS ) may give those that would do America ill an opportunity to turn one of our greatest military assets against us or deny US forces its

  12. What Happens If the Stars Go Out? U.S. Army Dependence on the Global Positioning System

    DTIC Science & Technology

    2009-12-11

    WHAT HAPPENS IF THE STARS GO OUT? U.S. ARMY DEPENDENCE ON THE GLOBAL POSITIONING SYSTEM A thesis presented to the Faculty of the U.S...DATES COVERED (From - To) FEB 2009 – DEC 2009 4. TITLE AND SUBTITLE What Happens if the Stars Go Out? U.S. Army Dependence on the Global...APPROVAL PAGE Name of Candidate: LCDR Thomas M. McGrath Thesis Title: What Happens if the Stars Go Out? U.S. Army Dependence on the Global

  13. 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

  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. Accuracy of a low-cost global positioning system receiver for estimating grade during outdoor walking.

    PubMed

    de Müllenheim, Pierre-Yves; Chaudru, Ségolène; Gernigon, Marie; Mahé, Guillaume; Bickert, Sandrine; Prioux, Jacques; Noury-Desvaux, Bénédicte; Le Faucheur, Alexis

    2016-09-21

    The aim of this study was to assess, for the first time, the accuracy of a low-cost global positioning system (GPS) receiver for estimating grade during outdoor walking. Thirty subjects completed outdoor walks (2.0, 3.5 and 5.0 km · h(-1)) in three randomized conditions: 1/level walking on a 0.0% grade; 2/graded (uphill and downhill) walking on a 3.4% grade; and 3/on a 10.4% grade. Subjects were equipped with a GPS receiver (DG100, GlobalSat Technology Corp., Taiwan; ~US$75). The GPS receiver was set to record at 1 Hz and its antenna was placed on the right shoulder. Grade was calculated from GPS speed and altitude data (grade  =  altitude variation/travelled distance  ×  100). Two methods were used for the grade calculation: one using uncorrected altitude data given by the GPS receiver and another one using corrected altitude data obtained using map projection software (CartoExploreur, version 3.11.0, build 2.6.6.22, Bayo Ltd, Appoigny, France, ~US$35). Linear regression of GPS-estimated versus actual grade with R (2) coefficients, bias with 95% limits of agreement (±95% LoA), and typical error of the estimate with 95% confidence interval (TEE (95% CI)) were computed to assess the accuracy of the GPS receiver. 444 walking periods were performed. Using uncorrected altitude data, we obtained: R (2)  =  0.88 (p  <  0.001), bias  =  0.0  ±  6.6%, TEE between 1.9 (1.7-2.2)% and 4.2 (3.6-4.9)% according to the grade level. Using corrected altitude data, we obtained: R (2)  =  0.98 (p  <  0.001), bias  =  0.2  ±  1.9%, TEE between 0.2 (0.2-0.3)% and 1.0 (0.9-1.2)% according to the grade level. The low-cost GPS receiver used was weakly accurate for estimating grade during outdoor walking when using uncorrected altitude data. However, the accuracy was greatly improved when using corrected altitude data. This study supports the potential interest of using GPS for estimating energy

  17. Methodological Considerations When Quantifying High-Intensity Efforts in Team Sport Using Global Positioning System Technology.

    PubMed

    Varley, Matthew C; Jaspers, Arne; Helsen, Werner F; Malone, James J

    2017-01-04

    Purpose Sprints and accelerations are popular performance indicators in applied sport. The methods used to define these efforts using athlete tracking technology could affect the number of efforts reported. The study aimed to determine the influence of different techniques and settings for detecting high-intensity efforts using Global Positioning System (GPS) data. Methods Velocity and acceleration data of a professional soccer match was recorded via 10-Hz GPS. Velocity data was filtered using either a median or exponential filter. Acceleration data was derived from velocity data over a 0.2 s time interval (with and without an exponential filter applied) and a 0.3 s time interval. High-speed running (≥4.17 m.s(-1)), sprint (≥7.00 m.(s-1)) and acceleration (≥2.78 m.s(-2)) efforts were then identified using minimum effort durations (0.1 to 0.9 s) to assess differences in the total number of efforts reported. Results Different velocity filtering methods resulted in small to moderate differences (Effect Size; 0.28 - 1.09) in the number of high-speed running and sprint efforts detected when minimum duration was <0.5 s and small to very large differences (ES; -5.69 - 0.26) in the number of accelerations when minimum duration was <0.7 s. There was an exponential decline in the number of all efforts as minimum duration increased, regardless of filtering method, with the largest declines in acceleration efforts. Conclusions Filtering techniques and minimum durations substantially affect the number of high-speed running, sprint and acceleration efforts detected with GPS. Changes to how high-intensity efforts are defined affect reported data. Therefore, consistency in data processing is advised.

  18. Assessing the contribution of parks to physical activity using global positioning system and accelerometry.

    PubMed

    Evenson, Kelly R; Wen, Fang; Hillier, Amy; Cohen, Deborah A

    2013-10-01

    Parks offer a free option for physical activity in many communities. How much time people spend using parks and the contribution that parks makes to their physical activity is not known. This study describes patterns of park use and physical activity among a diverse adult sample. From five US states, 248 adults enrolled in or near 31 study parks. Participants wore a global positioning system (GPS) monitor (Qstarz BT-Q1000X) and an ActiGraph accelerometer (GT1M) concurrently for 3 wk. Parks were mapped from local and national park shape files. Park visits and travel to and from the parks were derived from the objective data. Participants visited parks a median of 2.3 times per week, and park visits lasted a median of 42.0 min. Overall, participants engaged in a median of 21.7 min·d-1 of moderate activity and 0.1 min·d-1 of vigorous activity, with an average of 8.2% of all moderate and 9.4% of all vigorous activity occurring within the parks. Among those with at least one park visit (n = 218), counts per minute, moderate, moderate-to-vigorous physical activity (MVPA), number and time in MVPA bouts per day, and sedentary behavior were all higher on days when a park was visited compared with days when a park was not visited. Considering several definitions of active travel, walking or bicycling to and from the park added an additional 3.7-6.6 mean minutes of MVPA per park visit. Parks contributed as a place and destination for physical activity but were underused. One of the next steps in this line of inquiry is to understand characteristics of parks used more often as a place and destination for physical activity.

  19. 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.

  20. 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.

  1. Use of global positioning system for physical activity research in youth: ESPAÇOS Adolescentes, Brazil.

    PubMed

    Alberico, Claudia Oliveira; Schipperijn, Jasper; Reis, Rodrigo S

    2016-12-23

    The built environment is an important factor associated with physical activity and sedentary behavior (SB) during adolescence. This study presents the methods for objective assessment of context-specific moderate to vigorous physical activity (MVPA) and SB, as well as describes results from the first project using such methodology in adolescents from a developing country. An initial sample of 381 adolescents was recruited from 32 census tracts in Curitiba, Brazil (2013); 80 had their homes geocoded and wore accelerometer and GPS devices for seven days. Four domains were defined as important contexts: home, school, transport and leisure. The majority of participants (n=80) were boys (46; 57.5%), with a normal BMI (52; 65.0%) and a mean age (SD) of 14.5 (5.5) years. Adolescents spent most of their time at home, engaging in SB. Overall, the largest proportion of MVPA was while in transport (17.1% of time spent in this context) and SB while in leisure (188.6min per day). Participants engaged in MVPA for a median of 28.7 (IQR 18.2-43.2) and 17.9 (IQR 9.2-32.1) minutes during week and weekend days, respectively. Participants spent most of their day in the leisure and home domains. The use of Geographic Information System (GIS), Global Positioning System (GPS) and accelerometer data allowed objective identification of the amount of time spent in MVPA and SB in four different domains. Though the combination of objective measures is still an emerging methodology, this is a promising and feasible approach to understanding interactions between people and their environments in developing countries.

  2. 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.

  3. 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

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

    PubMed

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

    2015-01-01

    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). 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. 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). 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 genders, although infrequently visited during

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Development of a wearable global positioning system for place and health research

    PubMed Central

    Rainham, Daniel; Krewski, Daniel; McDowell, Ian; Sawada, Mike; Liekens, Brian

    2008-01-01

    Background An increasing number of studies suggest that characteristics of context, or the attributes of the places within which we live, work and socialize, are associated with variations in health-related behaviours and outcomes. The challenge for health research is to ensure that these places are accurately represented spatially, and to identify those aspects of context that are related to variations in health and amenable to modification. This study focuses on the design of a wearable global positioning system (GPS) data logger for the purpose of objectively measuring the temporal and spatial features of human activities. Person-specific GPS data provides a useful source of information to operationalize the concept of place. Results We designed and tested a lightweight, wearable GPS receiver, capable of logging location information for up to 70 hours continuously before recharging. The device is accurate to within 7 m in typical urban environments and performs well across a range of static and dynamic conditions. Discussion Rather than rely on static areal units as proxies for places, wearable GPS devices can be used to derive a more complete picture of the different places that influence an individual's wellbeing. The measures are objective and are less subject to biases associated with recall of location or misclassification of contextual attributes. This is important for two reasons. First, it brings a dynamic perspective to place and health research. The influence of place on health is dynamic in that certain places are more or less relevant to wellbeing as determined by the length of time in any location and by the frequency of activity in the location. Second, GPS data can be used to assess whether the characteristics of places at specific times are useful to explaining variations in health and wellbeing. PMID:19032783

  10. Global positioning systems (GPS) and microtechnology sensors in team sports: a systematic review.

    PubMed

    Cummins, Cloe; Orr, Rhonda; O'Connor, Helen; West, Cameron

    2013-10-01

    Use of Global positioning system (GPS) technology in team sport permits measurement of player position, velocity, and movement patterns. GPS provides scope for better understanding of the specific and positional physiological demands of team sport and can be used to design training programs that adequately prepare athletes for competition with the aim of optimizing on-field performance. The objective of this study was to conduct a systematic review of the depth and scope of reported GPS and microtechnology measures used within individual sports in order to present the contemporary and emerging themes of GPS application within team sports. A systematic review of the application of GPS technology in team sports was conducted. We systematically searched electronic databases from earliest record to June 2012. Permutations of key words included GPS; male and female; age 12-50 years; able-bodied; and recreational to elite competitive team sports. The 35 manuscripts meeting the eligibility criteria included 1,276 participants (age 11.2-31.5 years; 95 % males; 53.8 % elite adult athletes). The majority of manuscripts reported on GPS use in various football codes: Australian football league (AFL; n = 8), soccer (n = 7), rugby union (n = 6), and rugby league (n = 6), with limited representation in other team sports: cricket (n = 3), hockey (n = 3), lacrosse (n = 1), and netball (n = 1). Of the included manuscripts, 34 (97 %) detailed work rate patterns such as distance, relative distance, speed, and accelerations, with only five (14.3 %) reporting on impact variables. Activity profiles characterizing positional play and competitive levels were also described. Work rate patterns were typically categorized into six speed zones, ranging from 0 to 36.0 km·h⁻¹, with descriptors ranging from walking to sprinting used to identify the type of activity mainly performed in each zone. With the exception of cricket, no standardized speed zones or definitions were observed within or

  11. 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.

  12. Indirect field-oriented control of induction motors is globally asymptotically stable when used to regulate position in rigid robots

    NASA Astrophysics Data System (ADS)

    Hernández-Guzmán, Victor M.; Santibáñez, Victor; Silva-Ortigoza, Ramón

    2010-10-01

    In this note we prove, for the first time, that indirect field-oriented control of voltage-fed induction motors achieves global asymptotic stability when used to regulate position in rigid robots. This results in the simplest controller proposed until now to solve this problem. Our stability analysis considers inner current loops driven by linear PI controllers and an external position loop driven by a saturated PD controller.

  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

    2016-12-01

    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. 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…

  15. 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…

  16. 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'…

  17. 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)

  18. 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.

  19. 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'…

  20. Augmenting the Global Positioning System with Foreign Navigation Systems and Alternative Sensors

    DTIC Science & Technology

    2012-03-01

    17 GLONASS Global Navigation Satellite System . . . . . . . . . . . . . . . . . . . . 18 FDMA Frequency Division Multiple... FDMA ). The frequency spectrum is broken down into two sub-bands from which the GLONASS channels derive their specific frequencies. The channels are

  1. Predicting ambulance time of arrival to the emergency department using global positioning system and Google maps.

    PubMed

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

    2013-01-01

    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.

  2. 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

  3. 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

  4. Global Positioning System (GPS) Determination of Motions, Neotectonics, and Seismic Risk in Trinidad and Tobago

    NASA Astrophysics Data System (ADS)

    Rodriguez, A. B.; Weber, J. C.; Schmalzle, G. M.

    2008-12-01

    The twin island nation of Trinidad and Tobago is located in the actively deforming Caribbean-South American (Ca-SA) plate boundary zone. Recent GPS (Global Positioning System) studies have accurately determined the relative plate motion between the Caribbean plate and South American plates: ~east-west, dextral motion at 20 mm/yr. Earthquakes do not clearly mark many of the active faults in Trinidad. A low-precision triangulation-to-GPS comparison at 23 sites and paleoseismology showed that significant strike-slip faulting is probably occurring on the Central Range Fault (CRF). The lack of recent seismic activity on the CRF may indicate that it is elastically locked and storing motion. We study Trinidad's neotectonics using new GPS data from 19 high-stability campaign sites that were built and measured in 2005, then measured again in 2007; for a few additional sites we have data that go back from 2007 to 1994. These new data will allow us to test and refine the previous lower-precision geodetic results to better quantify the rate of slip across the CRF and its mechanical behavior. We compiled, and then processed the data using GIPSY/OASIS II (Release 5.0) software at the University of Miami RSMAS Geodesy Lab. We find that, in a South American reference frame, sites north of the CRF move at about 20 (±1-5) mm/yr; sites south of the CRF are stationary (±1-8 mm/yr). Tobago site velocities are slightly oblique to overall Caribbean plate motion due to a major (Magnitude 6.7) earthquake that occurred off Tobago's south coast in 1997. Our new results support the hypotheses that the CRF is the principal active strike-slip fault in Trinidad (i.e., is the current Ca-SA plate boundary). We are fitting locked fault (elastic dislocation half-space) models to the data which will allow us to look more closely at the mechanical behavior of the CRF to further test whether it is locked or creeping to help evaluate its seismic risk.

  5. 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

  6. Crustal deformation in the central California coast region inferred from Global Positioning System data

    NASA Astrophysics Data System (ADS)

    Murray-Moraleda, J. R.; Thatcher, W. R.; Onishi, C. T.; Svarc, J. L.

    2011-12-01

    The Central California Coast Region (CCCR), defined here as the area from north of Point Piedras Blancas (36°N) south to Point Arguello (34.6°N) and west of the Rinconada and East Huasna faults, is a structurally complex region cut by several subparallel, late Quaternary faults. Despite relatively low rates of deformation inferred from geologic studies of the CCCR, the occurrence of the 2003 Mw 6.5 San Simeon earthquake southeast of Point Piedras Blancas highlights the need to better understand the ongoing patterns of deformation here as a means for assessing the seismic hazard. Geological and geophysical data from this region have been interpreted as evidence for ongoing transpression due to the clockwise rotation of the Transverse Ranges which would predict crustal contraction normal to the plate boundary. However an alternative interpretation concludes that the region instead experiences the active westward transfer of right-lateral strike-slip motion in a left-stepping fashion which would result in northwest-southeast contraction. Geodetic data can be used to elucidate how strain is currently partitioned between shear parallel to the San Andreas Fault (SAF) and contraction within the CCCR and to identify actively deforming structures. We use a newly compiled Global Positioning System (GPS) secular velocity field for the CCCR as well as GPS velocities for the greater southern California region from the SCEC Crustal Motion Map v.4 and the EarthScope Plate Boundary Observatory velocity solution to constrain block models of deformation. We solve for the rotation of fault-bounded blocks, fault slip rates, and internal strain within blocks. Results thus far indicate that the data do not require substantial slip on the Rinconada fault (for which the estimated slip rate is ~2 mm/yr) or on the Oceanic and West Huasna faults that bound the eastern edge of the CCCR in an alternative block configuration (for which the estimated slip rate is <1 mm/yr). The data also do

  7. 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

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

    PubMed

    Wu, Jun; Jiang, Chengsheng; Jaimes, Guillermo; Bartell, Scott; Dang, Andy; Baker, Dean; Delfino, Ralph J

    2013-10-09

    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. 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. 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. 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 higher education attainment, higher income

  9. 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

  10. 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.

  11. A Biological Global Positioning System: Considerations for Tracking Stem Cell Behaviors in the Whole Body

    PubMed Central

    Tachiki, Lisa May Ling; Luo, Jane; Dethlefs, Brent A.; Chen, Zhongping; Loudon, William G.

    2010-01-01

    Many recent research studies have proposed stem cell therapy as a treatment for cancer, spinal cord injuries, brain damage, cardiovascular disease, and other conditions. Some of these experimental therapies have been tested in small animals and, in rare cases, in humans. Medical researchers anticipate extensive clinical applications of stem cell therapy in the future. The lack of basic knowledge concerning basic stem cell biology-survival, migration, differentiation, integration in a real time manner when transplanted into damaged CNS remains an absolute bottleneck for attempt to design stem cell therapies for CNS diseases. A major challenge to the development of clinical applied stem cell therapy in medical practice remains the lack of efficient stem cell tracking methods. As a result, the fate of the vast majority of stem cells transplanted in the human central nervous system (CNS), particularly in the detrimental effects, remains unknown. The paucity of knowledge concerning basic stem cell biology—survival, migration, differentiation, integration in real-time when transplanted into damaged CNS remains a bottleneck in the attempt to design stem cell therapies for CNS diseases. Even though excellent histological techniques remain as the gold standard, no good in vivo techniques are currently available to assess the transplanted graft for migration, differentiation, or survival. To address these issues, herein we propose strategies to investigate the lineage fate determination of derived human embryonic stem cells (hESC) transplanted in vivo into the CNS. Here, we describe a comprehensive biological Global Positioning System (bGPS) to track transplanted stem cells. But, first, we review, four currently used standard methods for tracking stem cells in vivo: magnetic resonance imaging (MRI), bioluminescence imaging (BLI), positron emission tomography (PET) imaging and fluorescence imaging (FLI) with quantum dots. We summarize these modalities and propose criteria

  12. 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

  13. 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

  14. Automated time activity classification based on global positioning system (GPS) tracking data

    PubMed Central

    2011-01-01

    Background Air pollution epidemiological studies are increasingly using global positioning system (GPS) to collect time-location data because they offer continuous tracking, high temporal resolution, and minimum reporting burden for participants. However, substantial uncertainties in the processing and classifying of raw GPS data create challenges for reliably characterizing time activity patterns. We developed and evaluated models to classify people's major time activity patterns from continuous GPS tracking data. Methods We developed and evaluated two automated models to classify major time activity patterns (i.e., indoor, outdoor static, outdoor walking, and in-vehicle travel) based on GPS time activity data collected under free living conditions for 47 participants (N = 131 person-days) from the Harbor Communities Time Location Study (HCTLS) in 2008 and supplemental GPS data collected from three UC-Irvine research staff (N = 21 person-days) in 2010. Time activity patterns used for model development were manually classified by research staff using information from participant GPS recordings, activity logs, and follow-up interviews. We evaluated two models: (a) a rule-based model that developed user-defined rules based on time, speed, and spatial location, and (b) a random forest decision tree model. Results Indoor, outdoor static, outdoor walking and in-vehicle travel activities accounted for 82.7%, 6.1%, 3.2% and 7.2% of manually-classified time activities in the HCTLS dataset, respectively. The rule-based model classified indoor and in-vehicle travel periods reasonably well (Indoor: sensitivity > 91%, specificity > 80%, and precision > 96%; in-vehicle travel: sensitivity > 71%, specificity > 99%, and precision > 88%), but the performance was moderate for outdoor static and outdoor walking predictions. No striking differences in performance were observed between the rule-based and the random forest models. The random forest model was fast and easy to execute

  15. Global mRNA decay analysis at single nucleotide resolution reveals segmental and positional degradation patterns in a Gram-positive bacterium

    PubMed Central

    2012-01-01

    Background Recent years have shown a marked increase in the use of next-generation sequencing technologies for quantification of gene expression (RNA sequencing, RNA-Seq). The expression level of a gene is a function of both its rate of transcription and RNA decay, and the influence of mRNA decay rates on gene expression in genome-wide studies of Gram-positive bacteria is under-investigated. Results In this work, we employed RNA-Seq in a genome-wide determination of mRNA half-lives in the Gram-positive bacterium Bacillus cereus. By utilizing a newly developed normalization protocol, RNA-Seq was used successfully to determine global mRNA decay rates at the single nucleotide level. The analysis revealed positional degradation patterns, with mRNAs being degraded from both ends of the molecule, indicating that both 5' to 3' and 3' to 5' directions of RNA decay are present in B. cereus. Other operons showed segmental degradation patterns where specific ORFs within polycistrons were degraded at variable rates, underlining the importance of RNA processing in gene regulation. We determined the half-lives for more than 2,700 ORFs in B. cereus ATCC 10987, ranging from less than one minute to more than fifteen minutes, and showed that mRNA decay rate correlates globally with mRNA expression level, GC content, and functional class of the ORF. Conclusions To our knowledge, this study presents the first global analysis of mRNA decay in a bacterium at single nucleotide resolution. We provide a proof of principle for using RNA-Seq in bacterial mRNA decay analysis, revealing RNA processing patterns at the single nucleotide level. PMID:22537947

  16. 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.

  17. 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

  18. 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…

  19. 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…

  20. 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…

  1. 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…

  2. 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…

  3. Interferometric attitude determination using the global positioning system - A new gyrotheodolite

    NASA Astrophysics Data System (ADS)

    Brown, A. K.; Thorvaldsen, T. P.; Bowles, W. M.

    A GPS receiver can measure absolute position to 5 meters. However, it is possible to measure relative position more accurately by using interferometry on the GPS carrier to measure heading. Simulation has shown that a dynamically aided, three antennae, short baselength GPS interferometer can measure heading to an accuracy of 50 microrad. Relative position can be determined from this heading measurement by sighting onto control stations with a theodolite mounted on the interferometer. If the control stations were 1 km distant it would be possible to measure relative position, using a GPS interferometer, to within 5 cm.

  4. Invited review: A position on the Global Livestock Environmental Assessment Model (GLEAM).

    PubMed

    MacLeod, M J; Vellinga, T; Opio, C; Falcucci, A; Tempio, G; Henderson, B; Makkar, H; Mottet, A; Robinson, T; Steinfeld, H; Gerber, P J

    2017-08-09

    The livestock sector is one of the fastest growing subsectors of the agricultural economy and, while it makes a major contribution to global food supply and economic development, it also consumes significant amounts of natural resources and alters the environment. In order to improve our understanding of the global environmental impact of livestock supply chains, the Food and Agriculture Organization of the United Nations has developed the Global Livestock Environmental Assessment Model (GLEAM). The purpose of this paper is to provide a review of GLEAM. Specifically, it explains the model architecture, methods and functionality, that is the types of analysis that the model can perform. The model focuses primarily on the quantification of greenhouse gases emissions arising from the production of the 11 main livestock commodities. The model inputs and outputs are managed and produced as raster data sets, with spatial resolution of 0.05 decimal degrees. The Global Livestock Environmental Assessment Model v1.0 consists of five distinct modules: (a) the Herd Module; (b) the Manure Module; (c) the Feed Module; (d) the System Module; (e) the Allocation Module. In terms of the modelling approach, GLEAM has several advantages. For example spatial information on livestock distributions and crops yields enables rations to be derived that reflect the local availability of feed resources in developing countries. The Global Livestock Environmental Assessment Model also contains a herd model that enables livestock statistics to be disaggregated and variation in livestock performance and management to be captured. Priorities for future development of GLEAM include: improving data quality and the methods used to perform emissions calculations; extending the scope of the model to include selected additional environmental impacts and to enable predictive modelling; and improving the utility of GLEAM output.

  5. 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.

  6. Non-Differentiable Exact Solutions for the Nonlinear Odes Defined on Fractal Sets

    NASA Astrophysics Data System (ADS)

    Yang, Xiao-Jun; Gao, Feng; Srivastava, H. M.

    In the present paper, a family of the special functions via the celebrated Mittag-Leffler function defined on the Cantor sets is investigated. The nonlinear local fractional ODEs (NLFODEs) are presented by following the rules of local fractional derivative (LFD). The exact solutions for these problems are also discussed with the aid of the non-differentiable charts on Cantor sets. The obtained results are important for describing the characteristics of the fractal special functions.

  7. 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.

  8. Dialogical Self Theory and the increasing multiplicity of I-positions in a globalizing society: an introduction.

    PubMed

    Hermans, Hubert J M

    2012-01-01

    Dialogical Self Theory is a recent development in the social sciences, based on a conception of the self as a society of mind. In this conception, the self is considered as extended to significant others in the environment, who populate the self as a dynamic multiplicity of I-positions between which dialogical or monological relationships may emerge. While from a spatial perspective the self is engaged in a process of positioning and counterpositioning in a globalizing society, from a temporal point of view the self is part of a process of positioning and repositioning in collective history and personal development. Some phenomena that are necessary for the understanding of the dialogical self are discussed: dominance and social power, the processes of globalization and localization, the experience of uncertainty and possible reactions to uncertainty in a globalizing world. Finally, the different contributions of this special issue are placed in the context of the presented conceptual framework. Copyright © 2012 Wiley Periodicals, Inc., A Wiley Company.

  9. Geoscience Australia Continuous Global Positioning System (CGPS) Station Field Campaign Report

    SciTech Connect

    Ruddick, R.; Twilley, B.

    2016-03-01

    This station formed part of the Australian Regional GPS Network (ARGN) and South Pacific Regional GPS Network (SPRGN), which is a network of continuous GPS stations operating within Australia and its Territories (including Antarctica) and the Pacific. These networks support a number of different science applications including maintenance of the Geospatial Reference Frame, both national and international, continental and tectonic plate motions, sea level rise, and global warming.

  10. 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.

  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; 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. 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

  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

    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 δ(15)N 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 δ(15)N values of individual amino acids are nearly uniform within both families of these fishes across five global regions despite great variability in bulk tissue δ(15)N values. Regional differences in the δ(15)N values of phenylalanine confirmed that bulk tissue δ(15)N values reflect region-specific water mass biogeochemistry controlling δ(15)N 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.

  15. Framework For A Software-defined Global Positioning System (GPS) Receiver For Precision Munitions Applications

    DTIC Science & Technology

    2012-04-01

    radio (SDR) approach is used for the development of global navigation satellite systems ( GNSS ) receivers. This approach provides an evaluation...antenna gain) of the generated C/A signal is broadcast from the satellite through the atmosphere to the receiver. This loss can be approximated to be...the sum of the free space path loss , approximately 182.4 dB, atmospheric loss , 2–3 dB, and receiver antenna gain, +1 dB to < −40 dB (9), which will

  16. Ionospheric Slant Total Electron Content Analysis Using Global Positioning System Based Estimation

    NASA Technical Reports Server (NTRS)

    Sparks, Lawrence C. (Inventor); Mannucci, Anthony J. (Inventor); Komjathy, Attila (Inventor)

    2017-01-01

    A method, system, apparatus, and computer program product provide the ability to analyze ionospheric slant total electron content (TEC) using global navigation satellite systems (GNSS)-based estimation. Slant TEC is estimated for a given set of raypath geometries by fitting historical GNSS data to a specified delay model. The accuracy of the specified delay model is estimated by computing delay estimate residuals and plotting a behavior of the delay estimate residuals. An ionospheric threat model is computed based on the specified delay model. Ionospheric grid delays (IGDs) and grid ionospheric vertical errors (GIVEs) are computed based on the ionospheric threat model.

  17. 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.

  18. 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

  19. 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.

  20. Integration of the B-52G Offensive Avionics System (OAS) with the Global Positioning System (GPS)

    NASA Astrophysics Data System (ADS)

    Foote, A. L.; Pluntze, S. C.

    Integration of the B-52G OAS with the GPS has been accomplished by modification of existing OAS software. GPS derived position and velocity data are used to enhance the quality of the OAS inertial and dead reckoning navigation systems. The engineering design and the software development process used to implement this design are presented.

  1. Global Distribution of Panton-Valentine Leukocidin–positive Methicillin-resistant Staphylococcus aureus, 2006

    PubMed Central

    Bes, Michele; Meugnier, Helene; Lina, Gerard; Bozdogan, Bülent; Courvalin, Patrice; Reverdy, Marie-Elisabeth; Enright, Mark C.; Vandenesch, François; Etienne, Jerome

    2007-01-01

    We determined the agr type, multilocus sequence type, protein A gene type (spa typing), toxin gene profile, and antimicrobial drug resistance profile of 469 isolates of Panton-Valentine leukocidin–positive community-acquired methicillin-resistant Staphylococcus aureus isolates (PVL-positive CA-MRSA). The isolates had been collected from around the world from 1999 through 2005 by the French National Reference Center for Staphylococci. We found that some continent-specific clones described in 2003, such as clone ST8, have now spread all over the world. Likewise, some PVL-positive CA-MRSA have spread to several countries on various continents. New clones have emerged (e.g., ST377) on new genetic backgrounds. PVL-positive CA-MRSA that were usually susceptible to most antistaphylococcal antimicrobial agents have acquired new resistance determinants (e.g., to gentamicin) in certain countries. The major trait shared by all these clones is a short staphylococcal chromosomal cassette mec element of type IV or V. PMID:17553275

  2. 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.

  3. Global Failure Criteria for SOFC Positive/Electrolyte/Negative (PEN) Structure

    SciTech Connect

    Liu, Wenning N.; Sun, Xin; Khaleel, Mohammad A.; Qu, Jianmin

    2007-04-01

    Due to the mismatch of thermal expansion coefficients (TEC) of the various layer materials in SOFC, the internal stresses are unavoidable under temperature differential. In order to create the reliable cell and stack of solid oxide fuel cell (SOFC), it is necessary to develop a failure criterion for SOFC PEN structures for the initial failures occurred during cell/stack assembly. In this paper, a global failure criterion is developed for the initial design against mechanical failure of the PEN structure in high temperature SOFCs. The relationship of the critical energy release rate and critical curvature and maximum displacement of the warpage of the cells caused by the temperature differential is established so that the failure reliability of SOFC PEN structures may be determined by the measurement of the curvature and displacement of the warpaged cells.

  4. Global RNA Half-Life Analysis in Escherichia coli Reveals Positional Patterns of Transcript Degradation

    PubMed Central

    Selinger, Douglas W.; Saxena, Rini Mukherjee; Cheung, Kevin J.; Church, George M.; Rosenow, Carsten

    2003-01-01

    Subgenic-resolution oligonucleotide microarrays were used to study global RNA degradation in wild-type Escherichia coli MG1655. RNA chemical half-lives were measured for 1036 open reading frames (ORFs) and for 329 known and predicted operons. The half-life of total mRNA was 6.8 min under the conditions tested. We also observed significant relationships between gene functional assignments and transcript stability. Unexpectedly, transcription of a single operon (tdcABCDEFG) was relatively rifampicin-insensitive and showed significant increases 2.5 min after rifampicin addition. This supports a novel mechanism of transcription for the tdc operon, whose promoter lacks any recognizable ς binding sites. Probe by probe analysis of all known and predicted operons showed that the 5′ ends of operons degrade, on average, more quickly than the rest of the transcript, with stability increasing in a 3′ direction, supporting and further generalizing the current model of a net 5′ to 3′ directionality of degradation. Hierarchical clustering analysis of operon degradation patterns revealed that this pattern predominates but is not exclusive. We found a weak but highly significant correlation between the degradation of adjacent operon regions, suggesting that stability is determined by a combination of local and operon-wide stability determinants. The 16 ORF dcw gene cluster, which has a complex promoter structure and a partially characterized degradation pattern, was studied at high resolution, allowing a detailed and integrated description of its abundance and degradation. We discuss the application of subgenic resolution DNA microarray analysis to study global mechanisms of RNA transcription and processing. PMID:12566399

  5. 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.

  6. A hand-held 3D laser scanning with global positioning system of subvoxel precision

    NASA Astrophysics Data System (ADS)

    Arias, Néstor; Meneses, Néstor; Meneses, Jaime; Gharbi, Tijani

    2011-01-01

    In this paper we propose a hand-held 3D laser scanner composed of an optical head device to extract 3D local surface information and a stereo vision system with subvoxel precision to measure the position and orientation of the 3D optical head. The optical head is manually scanned over the surface object by the operator. The orientation and position of the 3D optical head is determined by a phase-sensitive method using a 2D regular intensity pattern. This phase reference pattern is rigidly fixed to the optical head and allows their 3D location with subvoxel precision in the observation field of the stereo vision system. The 3D resolution achieved by the stereo vision system is about 33 microns at 1.8 m with an observation field of 60cm x 60cm.

  7. GPS (Global Positioning System) User Equipment Evaluation Techniques Using a Rotor Mounted Antenna

    DTIC Science & Technology

    1988-08-01

    MEASUREMENT PROCEDURE 5 6. RECOMMENDATIONS 6 REFERENCES 8 LIST OF FIGURES 1. Rotor induced Kalman filtr arror in reported position 9 2. Grid representing...centre will depend on Kalman filter characteristics and will tend to increase with rotor speed. GPS system noise was observed to obey Rayleigh...delayed difference measurement of reported diameter of antenna path to an accuracy of better than 0.5 m over 30 min. This method of Kalman error

  8. Study of the Impact of the Global Positioning System on Army Survey

    DTIC Science & Technology

    1976-09-01

    information with rela- tively low cost user equipment. It is a universal positioning system with the following characteristics: * Accurate three-dimensional...the universal surveying instru- ment. It can be used for all categories of low order survey to include measurement or horizontal and vertical angles...party consists of four men. The second method is slope taping wherein the tape may lie supported on its entire length and parellel to the ground. An

  9. On the local fractional derivative of everywhere non-differentiable continuous functions on intervals

    NASA Astrophysics Data System (ADS)

    Liu, Cheng-shi

    2017-01-01

    We first prove that for a continuous function f(x) defined on an open interval, the Kolvankar-Gangal's (or equivalently Chen-Yan-Zhang's) local fractional derivative f(α)(x) is not continuous, and then prove that it is impossible that the KG derivative f(α)(x) exists everywhere on the interval and satisfies f(α)(x) ≠ 0 in the same time. In addition, we give a criterion of the nonexistence of the local fractional derivative of everywhere non-differentiable continuous functions. Furthermore, we construct two simple nowhere differentiable continuous functions on (0, 1) and prove that they have no the local fractional derivatives everywhere.

  10. 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.

  11. Validation study of arm positions for evaluation of global spinal balance in EOS imaging.

    PubMed

    Kaneko, Kanichiro; Aota, Yoichi; Sekiya, Tatsuhiro; Yamada, Katsutaka; Saito, Tomoyuki

    2016-10-01

    The sagittal vertical axis (SVA) is important in the evaluation of spinal sagittal balance. Although the "fists-on-clavicles" (FOC) position has been widely used in radiographic examinations, it does not define shoulder flexion in detail. Meanwhile, in EOS imaging, the "hands-on-cheeks" (HOC) position is widely used but has not been well investigated. The purpose of this study was to investigate the relative usefulness of FOC and HOC in investigating SVA. Mean SVA was measured by EOS imaging using standing lateral radiographs of 34 volunteers in four different positions: relaxed (RLX), shoulder flexion at 90° with FOC (FOC90), elbows touching the trunk with FOC (FOCET), and HOC. The mean SVA was 2.0 ± 2.1 cm in RLX; -1.4 ± 3.2 cm in FOC90; -0.5 ± 3.0 cm in FOCET; and -0.2 ± 2.9 cm in HOC. The negative shift from RLX was significantly greater in FOC90 than in FOCET (-3.4 ± 2.2 vs -2.5 ± 2.4 cm; p = 0.0182). The negative shift from RLX in HOC was almost equal to that in FOCET; the difference was 0.3 cm (-2.2 ± 2.2 vs -2.5 ± 2.4 cm; p = 0.2560). FOC90 showed a negative SVA shift in comparison with FOCET. The difference in the mean SVA between HOC and FOCET was 0.3 cm, a clinically small difference.

  12. Chronic kidney disease as a global public health problem: approaches and initiatives - a position statement from Kidney Disease Improving Global Outcomes.

    PubMed

    Levey, A S; Atkins, R; Coresh, J; Cohen, E P; Collins, A J; Eckardt, K-U; Nahas, M E; Jaber, B L; Jadoul, M; Levin, A; Powe, N R; Rossert, J; Wheeler, D C; Lameire, N; Eknoyan, G

    2007-08-01

    Chronic kidney disease (CKD) is increasingly recognized as a global public health problem. There is now convincing evidence that CKD can be detected using simple laboratory tests, and that treatment can prevent or delay complications of decreased kidney function, slow the progression of kidney disease, and reduce the risk of cardiovascular disease (CVD). Translating these advances to simple and applicable public health measures must be adopted as a goal worldwide. Understanding the relationship between CKD and other chronic diseases is important to developing a public health policy to improve outcomes. The 2004 Kidney Disease Improving Global Outcomes (KDIGO) Controversies Conference on 'Definition and Classification of Chronic Kidney Disease' represented an important endorsement of the Kidney Disease Outcome Quality Initiative definition and classification of CKD by the international community. The 2006 KDIGO Controversies Conference on CKD was convened to consider six major topics: (1) CKD classification, (2) CKD screening and surveillance, (3) public policy for CKD, (4) CVD and CVD risk factors as risk factors for development and progression of CKD, (5) association of CKD with chronic infections, and (6) association of CKD with cancer. This report contains the recommendations from the meeting. It has been reviewed by the conference participants and approved as position statement by the KDIGO Board of Directors. KDIGO will work in collaboration with international and national public health organizations to facilitate implementation of these recommendations.

  13. Global position analysis of the Pseudomonas aeruginosa quorum-sensing transcription factor LasR.

    PubMed

    Gilbert, Kerrigan B; Kim, Tae Hoon; Gupta, Rashmi; Greenberg, E Peter; Schuster, Martin

    2009-09-01

    In Pseudomonas aeruginosa quorum sensing (QS), the transcriptional regulator LasR controls the expression of more than 300 genes. Several of these genes are activated indirectly via a second, subordinate QS regulator, RhlR. Conserved sequence elements upstream of individual other genes have been shown to bind LasR in vitro. To comprehensively identify all regions that are bound by LasR in vivo, we employed chromatin immunoprecipitation in conjunction with microarray analysis. We identified 35 putative promoter regions that direct the expression of up to 74 genes. In vitro DNA binding studies allowed us to distinguish between cooperative and non-cooperative LasR binding sites, and allowed us to build consensus sequences according to the mode of binding. Five promoter regions were not previously recognized as QS-controlled. Two of the associated transcript units encode proteins involved in the cold-shock response and in Psl exopolysaccharide synthesis respectively. The LasR regulon includes seven genes encoding transcriptional regulators, while secreted factors and secretion machinery are the most over-represented functional categories overall. This supports the notion that the core function of LasR is to co-ordinate the production of extracellular factors, although many of its effects on global gene expression are likely mediated indirectly by regulatory genes under its control.

  14. 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.

  15. 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

  16. 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.

  17. Global positioning system network analysis with phase ambiguity resolution applied to crustal deformation studies in California

    NASA Technical Reports Server (NTRS)

    Dong, Da-Nan; Bock, Yehuda

    1989-01-01

    An efficient algorithm is developed for multisession adjustment of GPS data with simultaneous orbit determination and ambiguity resolution. Application of the algorithm to the analysis of data from a five-year campaign in progress in southern and central California to monitor tectonic motions using observations by GPS satellites, demonstrates improvements in estimates of station position and satellite orbits when the phase ambiguities are resolved. Most of the phase ambiguities in the GPS network were resolved, particularly for all the baselines of geophysical interest in California.

  18. 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.

  19. 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

  20. 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

  1. High-precision orbit determination for high-earth elliptical orbiters using the Global Positioning System

    NASA Technical Reports Server (NTRS)

    Lichten, S. M.; Estefan, J. A.

    1990-01-01

    Orbit covariance analyses pertaining to the Japanese VLBI Space Observatory Program (VSOP) MUSES-B satellite and to the International VLBI Satellite are presented. It is determined that a combination of Doppler and GPS measurements can provide the orbit accuracy required to support advanced radio interferometric experiments. For the VSOP, the required orbit accuracy of 130 m is easily met with two-way Doppler as the primary type of data; the 0.4 cm/s VSOP velocity requirement is also feasible provided that precise ground calibrations of tropospheric delays and station coordinates are available. It is concluded that combining the data from a VSOP GPS flight instrument with the ground GPS and two-way Doppler data will significantly enhance orbit determination accuracy in position and velocity.

  2. Return to play in elite rugby union: application of global positioning system technology in return-to-running programs.

    PubMed

    Reid, Laura C; Cowman, Jason R; Green, Brian S; Coughlan, Garrett F

    2013-05-01

    Global positioning systems (GPS) are widely used in sport settings to evaluate the physical demands on players in training and competition. The use of these systems in the design and implementation of rehabilitation and return-to-running programs has not yet been elucidated. To demonstrate the application of GPS technology in the management of return to play in elite-club Rugby Union. Case series. Professional Rugby Union club team. 8 elite Rugby Union players (age 27.86 ± 4.78 y, height 1.85 ± 0.08 m, weight 99.14 ± 9.96 kg). Players wore GPS devices for the entire duration of a club game. Variables of locomotion speed and distance were measured. Differences in physical demands between playing positions were observed for all variables. An analysis of the position-specific physical demands measured by GPS provides key information regarding the level and volume of loads sustained by a player in a game environment. Using this information, sports-medicine practitioners can develop rehabilitation and return-to-running protocols specific to the player position to optimize safe return to play.

  3. Global positioning system measurements over a strain monitoring network in the eastern two-thirds of the United States

    SciTech Connect

    Strange, W.E.

    1991-09-01

    A 45-station geodetic network was established in 1987 using global positioning system (GPS) technology to provide a means of monitoring strain and deformation in the central and eastern United States. Reduction of the initial epoch data showed that accuracies of 1 to 3 cm can be achieved for horizontal position, provided sufficient observations are available and there are four or more fiducial stations whose positions are known a priori, for example from Very Long Baseline Interferometry measurements. Accuracies obtained provide the ability to determine strain at the 1:10{sup 7} to 1:10{sup 8} level. Vertical positions are less accurate because of problems in modeling refraction and are determined at the 5 to 7 cm level. It is planned to remeasure this network at regular intervals in the coming years to place bounds on the strain occurring in the central and eastern United States. This network is also expected to serve as a reference network for more detailed monitoring networks in areas of high risk such as the New Madrid area. Future measurements are expected to provide more accurate results because of increased numbers of GPS satellites available and improved computation software. The improved software will also allow future upgrading of the accuracy of the 1987 observations. 3 figs., 5 tabs.

  4. 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.

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

    PubMed Central

    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. PMID:23761772

  6. Use of global positioning systems to study physical activity and the environment: a systematic review.

    PubMed

    Krenn, Patricia J; Titze, Sylvia; Oja, Pekka; Jones, Andrew; Ogilvie, David

    2011-11-01

    The GPS represents an innovative way to objectively assess the spatial locations of physical activity behavior. The aim of this systematic review was to determine the capability of GPS to collect high-quality data on the location of activities in research on the relationship between physical activity and the environment. Published and unpublished articles identified from seven electronic databases, reference lists, bibliographies, and websites up to March 2010 were systematically searched for, appraised, and analyzed in summer 2010. Included studies used GPS to measure the spatial locations of physical activity and some form of environmental analysis related to the GPS data. The capability of GPS was expressed in terms of data quality, which in turn was defined as the proportion of GPS data lost in each study. 24 studies met the inclusion criteria. Data loss was positively correlated with the measurement period for which participants were asked to wear the GPS device (r=0.81, p<0.001). Major reasons for data loss included signal drop-outs, loss of device battery power, and poor adherence of participants to measurement protocols. Data loss did not differ significantly between children and adults or by study sample size, year of publication, or GPS device manufacturer. GPS is a promising tool for improving understanding of the spatial context of physical activity. The current findings suggest that the choice of an appropriate device and efforts to maximize participant adherence are key to improving data quality, especially over longer study periods. Copyright © 2011 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.

  7. Aircraft landing using a modernized global positioning system and the wide area augmentation system

    NASA Astrophysics Data System (ADS)

    Jan, Shau-Shiun

    This research investigates the performance of an airborne GPS receiver using differential corrections and associated error bounds from the WAAS when three civil GPS signals become available. There are three ways to take advantage of the multiple frequencies. First, one can measure ionospheric delay directly in the airplane. This would replace the grid of ionosphere delay corrections currently broadcast by the WAAS. This direct use of multiple frequencies would be more accurate, and offer higher availability. Second, one can use the additional GPS frequencies to mitigate unintentional radio frequency interference (RFI). Even if two frequencies are lost, the user could revert to the WAAS grid. Third, one can take advantage of stronger civil signal power of the modernized GPS to acquire a low elevation satellite before using it for the position solution. Earlier acquisition would allow for longer carrier-aided smoothing of multipath. This research evaluates the performance of a multiple-frequency GPS landing system that depends on the number of available GPS frequencies and includes the following scenarios: Case 1. All three GPS frequencies are available, Case 2. Two of three GPS frequencies are available, Case 3. One of three GPS frequencies is available. This research also presents a solution to sustain multiple frequency performance when an aircraft descends into an RFI field and loses all but one of the frequencies. There are three available techniques. First, one can use the code-carrier divergence to continue ionospheric delay estimation. Second, one can use the WAAS ionospheric threat model to bound the error. Third, one can use the maximum ionospheric delay gradient model to bound the ionospheric delay during the ionosphere storm period. These three techniques all provide the ability to continue operation for more than 10 minutes after the onset of RFI. This research provides the first three-frequency GPS/WAAS LPV coverage predictions for CONUS. The current L1

  8. Evolution of the Global Aurora During Positive IMF B(sub z) and Varying IMF B(sub y) Conditions

    NASA Technical Reports Server (NTRS)

    Cumnock, J. A.; Sharber, J. A.; Heelis, R. A.; Hairston, M. R.; Craven, 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 (IMF) 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 B(sub y) during northward Interplanetary Magnetic Field. Theta aurora are formed both from expanded duskside emission regions (B(sub y) changes from positive to negative) and dawnside emission regions (B(sub y) 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.

  9. A compact non-differential approach for modeling laser ablation plasma dynamics

    NASA Astrophysics Data System (ADS)

    Irimiciuc, S. A.; Gurlui, S.; Nica, P.; Focsa, C.; Agop, M.

    2017-02-01

    Various differentiable physical models are frequently used to describe the dynamics of laser-produced plasma plumes (e.g., kinetic models, two-fluid models, etc.). Given the complexity of all the phenomena involved in the laser-matter interactions, it is required to introduce the laser ablation plasma dynamic variable dependencies both on the space-time coordinates and on the resolution scales. Therefore, an adequate theoretical approach may be the use of non-differentiable physical models (fractal models). Continuing our previous work on the fractal hydrodynamic model for laser ablation plasma dynamics, we propose here a compact version for the analysis of the spatial and temporal evolution of some plasma dynamic variables, such as velocities, currents, number densities, or temperatures. Moreover, the influence of external factors on the ablation plasma dynamics is considered. The predictions of this model are compared with the experimental data obtained by using a Langmuir probe on an Aluminum laser-produced plasma.

  10. Non-differentiable minimax fractional programming with generalized [alpha]-univexity

    NASA Astrophysics Data System (ADS)

    Jayswal, Anurag

    2008-04-01

    In this paper, we study a non-differentiable minimax fractional programming problem under the assumption of generalized [alpha]-univex function. In this paper we extend the concept of [alpha]-invexity [M.A. Noor, On generalized preinvex functions and monotonicities, J. Inequalities Pure Appl. Math. 5 (2004) 1-9] and pseudo [alpha]-invexity [S.K. Mishra, M.A. Noor, On vector variational-like inequality problems, J. Math. Anal. Appl. 311 (2005) 69-75] to [alpha]-univexity and pseudo [alpha]-univexity from a view point of generalized convexity. We also introduce the concept of strict pseudo [alpha]-univex and quasi [alpha]-univex functions. We derive Karush-Kuhn-Tucker-type sufficient optimality conditions and establish weak, strong and converse duality theorems for the problem and its three different form of dual problems. The results in this paper extend a few known results in the literature.

  11. 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.

  12. Maintenance of time and frequency in the Jet Propulsion Laboratory's Deep Space Network using the Global Positioning System

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

    The Deep Space Network (DSN), managed by the Jet Propulsion Laboratory for NASA, must maintain time and frequency within specified limits in order to accurately track the spacecraft engaged in deep space exploration. Various methods are used to coordinate the clocks among the three tracking complexes. These methods include Loran-C, TV Line 10, Very Long Baseline Interferometry (VLBI), and the Global Positioning System (GPS). 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). Areas of discussion are: (1) a brief history of the GPS timing receivers in the DSN, (2) a description of the data and information flow, (3) data on the performance of the DSN master clocks and GPS measurement system, and (4) a description of hydrogen maser frequency steering using these data.

  13. Accuracy of time comparison derived from reception of LORAN-C and Global Positioning System time signals

    NASA Astrophysics Data System (ADS)

    Horiai, Koji

    1992-10-01

    The accuracy of time comparison by means of the reception of common time signals, namely, LORAN-C and Global Positioning System (GPS), is examined. Differences of UTC from the emission times of these two radio wave signals measured at four Japanese stations and one U.S. station are analyzed and compared with the clock comparison reports published by the Bureau International des Poids et Mesures. The accuracy of the time comparison via LORAN-C signals of the northwest Pacific chain is about 3.61 microns and that via GPS is 0.14 microns. The accuracy analysis reveals the existence of systematic errors at the individual stations. In LORAN-C, the most serious error comes from those in the delay time calibration of receiving instruments and estimation of the propagation delay over land. Calibration of the clocks by a portable clock improves the accuracy of the GPS method to the accuracy of the GPS signals.

  14. 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.

  15. Use of handheld computers with global positioning systems for probability sampling and data entry in household surveys.

    PubMed

    Vanden Eng, Jodi L; Wolkon, Adam; Frolov, Anatoly S; Terlouw, Dianne J; Eliades, M James; Morgah, Kodjo; Takpa, Vincent; Dare, Aboudou; Sodahlon, Yao K; Doumanou, Yao; Hawley, William A; Hightower, Allen W

    2007-08-01

    We introduce an innovative method that uses personal digital assistants (PDAs) equipped with global positioning system (GPS) units in household surveys to select a probability-based sample and perform PDA-based interviews. Our approach uses PDAs with GPS to rapidly map all households in selected areas, choose a random sample, and navigate back to the sampled households to conduct an interview. We present recent field experience in two large-scale nationally representative household surveys to assess insecticide-treated bed net coverage as part of malaria control efforts in Africa. The successful application of this method resulted in statistically valid samples; quality-controlled data entry; and rapid aggregation, analyses, and availability of preliminary results within days of completing the field work. We propose this method as an alternative to the Expanded Program on Immunization cluster sample method when a fast, statistically valid survey is required in an environment with little census information at the enumeration area level.

  16. The precise computation of geoid undulation differences with comparison to results obtained from the global positioning system

    NASA Technical Reports Server (NTRS)

    Engelis, T.; Rapp, R. H.; Tscherning, C. C.

    1984-01-01

    Ellipsoidal height differences have been determined for 13 station pairs in the central Ohio region using measurements made with the Global Positioning System. This information was used to compute geoid undulation differences based on known orthometric heights. These differences were compared to gravimetrically-computed undulations (using a Stokes integration procedure, and least squares collocation having an internal r.m.s. agreement of plus or minus 1 cm in undulation differences). The two sets of undulation differences have an r.m.s. discrepancy of plus or minus 5 cm while the average station separation is of the order of 14 km. This good agreement suggests that gravimetric data can be used to compute accurate geoid undulation differences that can be used to convert ellipsoidal height differences obtained from GPS to orthometric height differences.

  17. GATA2 provides an early anterior bias and uncovers a global positioning system for polarity in the amniote embryo

    PubMed Central

    Bertocchini, Federica; Stern, Claudio D.

    2013-01-01

    The first axis to be specified during vertebrate development is that between the site where gastrulation will begin and the opposite pole of the embryo (dorso-ventral axis in amphibians and fish, anterior-posterior in amniotes). This relies on Nodal activity, but different vertebrates differ in how this activity is positioned. In chick, the earliest known asymmetry is posterior expression of the TGFβ-related factor Vg1, close to the future Nodal expression domain. Here we show that the transcription factor GATA2 is expressed anteriorly before this stage. GATA2 influences the site of primitive streak formation and its role is independent from, and upstream of, Vg1 and Wnt. However while Vg1 is required for streak formation, GATA2 does not act as an absolute anterior specifier, but provides an anterior bias. These findings point to previously unsuspected global determinants of polarity of the early amniote embryo. PMID:23093427

  18. Gata2 provides an early anterior bias and uncovers a global positioning system for polarity in the amniote embryo.

    PubMed

    Bertocchini, Federica; Stern, Claudio D

    2012-11-01

    The first axis to be specified during vertebrate development is that between the site where gastrulation will begin and the opposite pole of the embryo (dorsoventral axis in amphibians and fish, anteroposterior in amniotes). This relies on Nodal activity, but different vertebrates differ in how this activity is positioned. In chick, the earliest known asymmetry is posterior expression of the TGFβ-related factor Vg1, close to the future Nodal expression domain. Here we show that the transcription factor Gata2 is expressed anteriorly before this stage. Gata2 influences the site of primitive streak formation and its role is independent from, and upstream of, Vg1 and Wnt. However, although Vg1 is required for streak formation, Gata2 does not act as an absolute anterior specifier, but provides an anterior bias. These findings point to previously unsuspected global determinants of polarity of the early amniote embryo.

  19. 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.

  20. 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.

  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. Estimating the position and orientation of a mobile robot with respect to a trajectory using omnidirectional imaging and global appearance.

    PubMed

    Payá, Luis; Reinoso, Oscar; Jiménez, Luis M; Juliá, Miguel

    2017-01-01

    Along the past years, mobile robots have proliferated both in domestic and in industrial environments to solve some tasks such as cleaning, assistance, or material transportation. One of their advantages is the ability to operate in wide areas without the necessity of introducing changes into the existing infrastructure. Thanks to the sensors they may be equipped with and their processing systems, mobile robots constitute a versatile alternative to solve a wide range of applications. When designing the control system of a mobile robot so that it carries out a task autonomously in an unknown environment, it is expected to take decisions about its localization in the environment and about the trajectory that it has to follow in order to arrive to the target points. More concisely, the robot has to find a relatively good solution to two crucial problems: building a model of the environment, and estimating the position of the robot within this model. In this work, we propose a framework to solve these problems using only visual information. The mobile robot is equipped with a catadioptric vision sensor that provides omnidirectional images from the environment. First, the robot goes along the trajectories to include in the model and uses the visual information captured to build this model. After that, the robot is able to estimate its position and orientation with respect to the trajectory. Among the possible approaches to solve these problems, global appearance techniques are used in this work. They have emerged recently as a robust and efficient alternative compared to landmark extraction techniques. A global description method based on Radon Transform is used to design mapping and localization algorithms and a set of images captured by a mobile robot in a real environment, under realistic operation conditions, is used to test the performance of these algorithms.

  4. Estimating the position and orientation of a mobile robot with respect to a trajectory using omnidirectional imaging and global appearance

    PubMed Central

    2017-01-01

    Along the past years, mobile robots have proliferated both in domestic and in industrial environments to solve some tasks such as cleaning, assistance, or material transportation. One of their advantages is the ability to operate in wide areas without the necessity of introducing changes into the existing infrastructure. Thanks to the sensors they may be equipped with and their processing systems, mobile robots constitute a versatile alternative to solve a wide range of applications. When designing the control system of a mobile robot so that it carries out a task autonomously in an unknown environment, it is expected to take decisions about its localization in the environment and about the trajectory that it has to follow in order to arrive to the target points. More concisely, the robot has to find a relatively good solution to two crucial problems: building a model of the environment, and estimating the position of the robot within this model. In this work, we propose a framework to solve these problems using only visual information. The mobile robot is equipped with a catadioptric vision sensor that provides omnidirectional images from the environment. First, the robot goes along the trajectories to include in the model and uses the visual information captured to build this model. After that, the robot is able to estimate its position and orientation with respect to the trajectory. Among the possible approaches to solve these problems, global appearance techniques are used in this work. They have emerged recently as a robust and efficient alternative compared to landmark extraction techniques. A global description method based on Radon Transform is used to design mapping and localization algorithms and a set of images captured by a mobile robot in a real environment, under realistic operation conditions, is used to test the performance of these algorithms. PMID:28464032

  5. 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

  6. 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.

  7. An accuracy assessment of positions obtained using survey- and recreational-grade Global Positioning System receivers across a range of forest conditions within the Tanana Valley of interior Alaska

    Treesearch

    Hans-Erik Andersen; Tobey Clarkin; Ken Winterberger; Jacob. Strunk

    2009-01-01

    The accuracy of recreational- and survey-grade global positioning system (GPS) receivers was evaluated across a range of forest conditions in the Tanana Valley of interior Alaska. High-accuracy check points, established using high-order instruments and closed-traverse surveying methods, were then used to evaluate the accuracy of positions acquired in different forest...

  8. Global Positioning System Bibliography

    DTIC Science & Technology

    1992-03-01

    01-280-5500 Standard Porn 298 (Rev 2-891 P-i"ritrlld bv ANSi 5d 3𔃻q-18 296 102 PREFACE This bibliography was prepared under Work Unit 32479, Dynamic...34 Presented at: ASCE Specialty Conference, GPS-88 Engineering Applications of GPS Satellite Surveying Technology, 11-14 May, Nashville, Tenn ., 27 pp. 4 Beck...Conference, GPS-83 Engineering Applications of GPS Satellite Surveying Technology, 11-14 May, Nashville, Tenn ., 9 pp. To be published in Journal of

  9. 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.

  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. Global positive expectancies in adolescence and health-related behaviours: longitudinal models of latent growth and cross-lagged effects.

    PubMed

    Carvajal, Scott C

    2012-01-01

    Constructs representative of global positive expectancies (GPE) such as dispositional optimism and hope have been theoretically and empirically linked to many positive mental and physical health outcomes. However such expectancies' health implications for adolescents, as well as their trajectory over time, are less well understood than for adult populations. This study tested whether GPE predict the key indicators of adolescents' future physical health status, their health-related behaviours. A prospective longitudinal study design was employed whereby a diverse population-based cohort (N = 744; mean age at baseline = 12) completed three surveys over approximately 18 months. Rigorous tests of causal predominance and reciprocal effects were conducted through latent growth and cross-panel structural equation models. Results showed GPE systematically decreased during the course of the study, yet higher initial levels of GPE predicted less alcohol drinking, healthier food choice and greater physical activity over time. GPE's protective relationships towards health protective behaviours (vs. health risk behaviours that also included tobacco smoking) appear more independent from depressive symptomatology, and the primary findings were robust across socio-demographic groups.

  13. A Flexible Binding Site Architecture Provides New Insights into CcpA Global Regulation in Gram-Positive Bacteria

    PubMed Central

    Yang, Yunpeng; Zhang, Lu; Huang, He; Yang, Chen; Yang, Sheng

    2017-01-01

    ABSTRACT Catabolite control protein A (CcpA) is the master regulator in Gram-positive bacteria that mediates carbon catabolite repression (CCR) and carbon catabolite activation (CCA), two fundamental regulatory mechanisms that enable competitive advantages in carbon catabolism. It is generally regarded that CcpA exerts its regulatory role by binding to a typical 14- to 16-nucleotide (nt) consensus site that is called a catabolite response element (cre) within the target regions. However, here we report a previously unknown noncanonical flexible architecture of the CcpA-binding site in solventogenic clostridia, providing new mechanistic insights into catabolite regulation. This novel CcpA-binding site, named crevar, has a unique architecture that consists of two inverted repeats and an intervening spacer, all of which are variable in nucleotide composition and length, except for a 6-bp core palindromic sequence (TGTAAA/TTTACA). It was found that the length of the intervening spacer of crevar can affect CcpA binding affinity, and moreover, the core palindromic sequence of crevar is the key structure for regulation. Such a variable architecture of crevar shows potential importance for CcpA’s diverse and fine regulation. A total of 103 potential crevar sites were discovered in solventogenic Clostridium acetobutylicum, of which 42 sites were picked out for electrophoretic mobility shift assays (EMSAs), and 30 sites were confirmed to be bound by CcpA. These 30 crevar sites are associated with 27 genes involved in many important pathways. Also of significance, the crevar sites are found to be widespread and function in a great number of taxonomically different Gram-positive bacteria, including pathogens, suggesting their global role in Gram-positive bacteria. PMID:28119470

  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. 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

  16. 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

  17. 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

  18. Performance analysis of professional, semiprofessional, and junior elite rugby league match-play using global positioning systems.

    PubMed

    McLellan, Christopher P; Lovell, Dale I

    2013-12-01

    The aim of the present study was to examine the positional differences in physical performance measures of professional, semiprofessional, and junior elite rugby league match-play using portable Global Positioning Systems (GPSs). Twelve professional, 12 semiprofessional, and 18 junior elite male rugby league players were monitored during 5 regular-season competition matches using portable GPS software. The mean total distance traveled during professional (8,371 ± 897 m) and semiprofessional (7,277 ± 734 m) match-play was significantly (p < 0.05) greater than that traveled during elite junior (4,646 ± 978 m) match-play. Position-specific total distance traveled and distance traveled per minute of playing time were significantly (p < 0.05) less for junior elite backs (5,768 ± 765 m; 74 ± 11 m·min) and forwards (4,774 ± 564 m; 82 ± 5 m·min) in comparison to those in professional (backs: 8,158 ± 673 m; 101 ± 8 m·min and forwards: 8,442 ± 812 m; 98 ± 12 m·min) and semiprofessional (backs: 7,505 ± 765 m; 94 ± 8 m·min and forwards: 6,701 ± 678 m; 89 ± 8 m·min) match-play. Maximum running speed, maximum sprints, and total sprint distance traveled by professional players were all significantly (p < 0.05) greater than those traveled by junior elite players but not semiprofessional players during match-play. Professional backs and forwards performed significantly (p < 0.05) more maximum sprints and traveled greater total distance during match-play in comparison to semiprofessional and junior elite players. The present findings demonstrate minimal differences in the physical performance measures of professional and semiprofessional rugby league match-play. The position-specific performance characteristics of junior elite match-play indicate that current junior elite player-development pathways may not provide adequate preparation for players transitioning into professional competition.

  19. 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.

  20. 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

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

    SciTech Connect

    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, we 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.

  2. 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

  3. 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.

  4. 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.; ...

    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

  5. Performances of different global positioning system devices for time-location tracking in air pollution epidemiological studies.

    PubMed

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

    2010-11-23

    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. 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. 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. All the tested GPS devices had limitations, but we identified several devices which showed promising performance for tracking subjects' time

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

    NASA Astrophysics Data System (ADS)

    Wagner, Chad R.; Mueller, David S.

    2011-05-01

    SummaryA 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.

  7. 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.

  8. Comparison of global positioning and computer-based tracking systems for measuring player movement distance during Australian football.

    PubMed

    Edgecomb, S J; Norton, K I

    2006-05-01

    Sports scientists require a thorough understanding of the energy demands of sports and physical activities so that optimal training strategies and game simulations can be constructed. A range of techniques has been used to both directly assess and estimate the physiological and biochemical changes during competition. A fundamental approach to understanding the contribution of the energy systems in physical activity has involved the use of time-motion studies. A number of tools have been used from simple pen and paper methods, the use of video recordings, to sophisticated electronic tracking devices. Depending on the sport, there may be difficulties in using electronic tracking devices because of concerns of player safety. This paper assesses two methods currently used to measure player movement patterns during competition: (1) global positioning technology (GPS) and (2) a computer-based tracking (CBT) system that relies on a calibrated miniaturised playing field and mechanical movements of the tracker. A range of ways was used to determine the validity and reliability of these methods for tracking Australian footballers for distance covered during games. Comparisons were also made between these methods. The results indicate distances measured using CBT overestimated the actual values (measured with a calibrated trundle wheel) by an average of about 5.8%. The GPS system overestimated the actual values by about 4.8%. Distances measured using CBT in experienced hands were as accurate as the GPS technology. Both systems showed relatively small errors in true distances.

  9. Accuracy of time comparison derived from reception of LORAN-C and Global Positioning System time signals.

    NASA Astrophysics Data System (ADS)

    Horiai, K.

    1992-10-01

    The accuracy of time comparison by means of the reception of common time signals, namely, LORAN-C and Global Positioning System (GPS), is examined. Differences of UTC from the emission times of these two radio wave signals measured at four Japanese stations and one U.S. station are analyzed and compared with the clock comparison reports published by the Bureau International des Poids et Mesures. The accuracy of the time comparison via LORAN-C signals of the northwest Pacific chain is about 3.61 μs and that via GPS is 0.14 μs. The accuracy analysis reveals the existence of systematic errors at the individual stations. In LORAN-C, the most serious error comes from those in the delay time calibration of receiving instruments and estimation of the propagation delay over land. Calibration of the clocks by a portable clock improves the accuracy of the GPS method to the accuracy of the GPS signals.

  10. Enhanced 911/global position system wizard: a telemedicine application for the prevention of severe hypoglycemia--monitor, alert, and locate.

    PubMed

    Dassau, Eyal; Jovanovic, Lois; Doyle, Francis J; Zisser, Howard C

    2009-11-01

    Intensive insulin therapy has an inherent risk of hypoglycemia that can lead to loss of consciousness, cardiac arrhythmia, seizure, and death ("dead-in-bed syndrome"). This risk of hypoglycemia is a major concern for patients, families, and physicians. The need for an automated system that can alert in the event of severe hypoglycemia is evident. In engineering systems, where there is a risk of malfunction of the primary control system, alert and safety mechanisms are implemented in layers of protection. This concept has been adopted in the proposed system that integrates a hypoglycemia prediction algorithm with a global position system (GPS) locator and short message service such that the current glucose value with the rate of change (ROC) and the location of the subject can be communicated to a predefined list. Furthermore, if the system is linked to the insulin pump, it can suspend the pump or decrease the basal insulin infusion rate to prevent the pending event. The system was evaluated on clinical datasets of glucose tracings from the DexCom Seven system. Glucose tracings were analyzed for hypoglycemia events and then a text message was broadcast to a predefined list of people who were notified with the glucose value, ROC, GPS coordinates, and a Google map of the location. In addition to providing a safety layer to a future artificial pancreas, this system also can be easily implemented in current continuous glucose monitors to help provide information and alerts to people with diabetes.

  11. 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.

  12. Physical game demands in elite rugby union: a global positioning system analysis and possible implications for rehabilitation.

    PubMed

    Coughlan, Garrett F; Green, Brian S; Pook, Paul T; Toolan, Eoin; O'Connor, Sean P

    2011-08-01

    Descriptive. To evaluate the physical demands of an international Rugby Union-level game using a global positioning system (GPS). Elite Rugby Union teams currently employ the latest technology to monitor and evaluate physical demands of training and games on their players. GPS data from 2 players, a back and a forward, were collected during an international Rugby Union game. Locomotion speed, total body load, and body load sustained in tackles and scrums were analyzed. Players completed an average distance of 6715 m and spent the major portion of the game standing or walking, interspersed with medium- and high-intensity running activities. The back performed a higher number of high-intensity sprints and reached a greater maximal speed. Body load data revealed that high levels of gravitational force are sustained in tackling and scrum tasks. The current study provides a detailed GPS analysis of the physical demands of international Rugby Union players. These data, when combined with game video footage, may assist sports medicine professionals in understanding the demands of the game and mechanism of injury, as well as improving injury rehabilitation.

  13. The application of geographic information systems and global positioning systems in humanitarian emergencies: lessons learned, programme implications and future research.

    PubMed

    Kaiser, Reinhard; Spiegel, Paul B; Henderson, Alden K; Gerber, Michael L

    2003-06-01

    Geographic information systems (GIS), global positioning systems and remote sensing have been increasingly used in public health settings since the 1990s, but application of these methods in humanitarian emergencies has been less documented. Recent areas of application of GIS methods in humanitarian emergencies include hazard, vulnerability, and risk assessments; rapid assessment and survey methods; disease distribution and outbreak investigations; planning and implementation of health information systems; data and programme integration; and programme monitoring and evaluation. The main use of GIS in these areas is to provide maps for decision-making and advocacy, which allow overlaying types of information that may not normally be linked. GIS is also used to improve data collection in the field (for example, for rapid health assessments or mortality surveys). Development of GIS methods requires further research. Although GIS methods may save resources and reduce error, initial investment in equipment and capacity building may be substantial. Especially in humanitarian emergencies, equipment and methodologies must be practical and appropriate for field use. Add-on software to process GIS data needs to be developed and modified. As equipment becomes more user-friendly and costs decrease, GIS will become more of a routine tool for humanitarian aid organisations in humanitarian emergencies, and new and innovative uses will evolve.

  14. Upper limit on the amplitude of gravitational waves around 0.1Â Hz from the Global Positioning System

    NASA Astrophysics Data System (ADS)

    Aoyama, Shohei; Tazai, Rina; Ichiki, Kiyotomo

    2014-03-01

    The global positioning system (GPS) is composed of 31 satellites having atomic clocks with 10-15 accuracy on board and enables one to calibrate the primary standard for frequency on the ground. Using the fact that oscillators on the ground have been successfully stabilized with high accuracy by receiving radio waves emitted from the GPS satellites, we set a constraint on the strain amplitude of the gravitational wave background hc. We find that the GPS has already placed a meaningful constraint, and the constraint on the continuous component of gravitational waves is given as hc<4.8×10-12(1/f) at 10-2≲f ≲100 Hz for stabilized oscillators with Δν /ν≃10-12. Thanks to the advantage of the Doppler tracking method, seismic oscillations do not affect the current constraint. Constraints on hc in the same frequency range from the velocity measurements by the lunar explorers in the Apollo mission are also derived.

  15. 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.

  16. 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.

  17. Position-independent geometric error identification and global sensitivity analysis for the rotary axes of five-axis machine tools

    NASA Astrophysics Data System (ADS)

    Guo, Shijie; Jiang, Gedong; Zhang, Dongsheng; Mei, Xuesong

    2017-04-01

    Position-independent geometric errors (PIGEs) are the fundamental errors of a five-axis machine tool. In this paper, to identify ten PIGEs peculiar to the rotary axes of five-axis machine tools with a tilting head, the mathematic model of the ten PIGEs is deduced and four measuring patterns are proposed. The measuring patterns and identifying method are validated on a five-axis machine tool with a tilting head, and the ten PIGEs of the machine tool are obtained. The sensitivities of the four adjustable PIGEs of the machine tool in different measuring patterns are analyzed by the Morris global sensitivity analysis method and the modifying method, and the procedure of the four adjustable PIGEs of the machine tool is given accordingly. Experimental results show that after and before modifying the four adjustable PIGEs, the average compensate rate reached 52.7%. It is proved that the proposed measuring, identifying, analyzing and modifying method are effective for error measurement and precision improvement of the five-axis machine tool.

  18. Analysis of performance in orienteering with treadmill tests and physiological field tests using a differential global positioning system.

    PubMed

    Larsson, Peter; Burlin, Lennart; Jakobsson, Erkki; Henriksson-Larsén, Karin

    2002-07-01

    The aim of this study was to determine the physiological responses to orienteering by examining the interrelationships between the information provided by a differential global positioning system (dGPS) about an orienteer's route, speed and orienteering mistakes, portable metabolic gas analyser data during orienteering and data from incremental treadmill tests. Ten male orienteers completed a treadmill threshold test and a field test; the latter was performed on a 4.3 km course on mixed terrain with nine checkpoints. The anaerobic threshold, threshold of decompensated metabolic acidosis, respiratory exchange ratio, onset of blood lactate accumulation and peak oxygen uptake (VO2peak) were determined from the treadmill test. Time to complete the course, total distance covered, mean speed, distance and timing of orienteering mistakes, mean oxygen uptake, mean relative heart rate, mean respiratory exchange ratio and mean running economy were computed from the dGPS data and metabolic gas analyser data. Correlation analyses showed a relationship between a high anaerobic threshold and few orienteering mistakes (r = - 0.64, P < 0.05). A high threshold of decompensated metabolic acidosis and VO2peak were related to a fast overall time (r = -0.70 to -0.72, P < 0.05) and high running speed (r = 0.64 to 0.79, P < 0.05 and P < 0.01, respectively), and were thus the best predictors of performance.

  19. 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.

  20. 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).

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

    NASA Astrophysics Data System (ADS)

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

    1992-04-01

    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.

  2. Positioning of ground-based Global Light System stations around the World for the JEM-EUSO mission

    NASA Astrophysics Data System (ADS)

    Norman, Zachary

    2013-04-01

    The astrophysical origins of the Extreme Energy Cosmic Rays (EECRs - E >10^20 eV) remain a matter of debate. Data obtained on EECRs is sparse, due to the very low flux reaching the Earth. The Extreme Universe Space Observatory on board the Japanese Experiment Module (JEM-EUSO) on the International Space Station (ISS) will measure the properties of EECRs by recording the UV light produced by the air showers in Earth's atmosphere from space. At these extremely high energies, there is no way to calibrate the detector and test its operation with man-made accelerators. However, it is possible to induce the detector to see a similar amount of light by using an array of Global Light System (GLS) stations, which will use xenon flashers and lasers. The GLS locations need to be representative of the different climates around the World, because the development of the air showers depends upon the general properties of the atmosphere where it occurs. In this context, a program was developed to predict when a given GLS station is able to fire test shots within the field of view of the JEM-EUSO detector as the ISS flies over. This program takes into account the trajectory of the ISS, the relative positions of the Sun and the Moon, as well as the average cloud cover over the candidate sites.

  3. 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).

  4. 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.

  5. 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.

  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. Re-examining the general positivity model of subjective well-being: the discrepancy between specific and global domain satisfaction.

    PubMed

    Oishi, S; Diener, E

    2001-08-01

    Three studies were conducted to examine the role of global life satisfaction in the discrepancy between specific and global domain satisfaction. Participants rated both global (e.g., education) and the corresponding, specific domain (e.g., professors, textbooks) satisfactions. In 3 studies, we found that individuals with higher life satisfaction evaluated global domain as a whole as more satisfying than those with lower life satisfaction, given the same level of satisfaction with specific domains. In Study 3, we also found that, given the same level of satisfaction during the previous 2 weeks, individuals with higher life satisfaction rated the global domains in general as more satisfying than those with lower life satisfaction. Overall, the association between globallife satisfaction and evaluative enhancement of global domains was most consistent in "self" and "social relationships." Finally, the effect of global life satisfaction on evaluative enhancement remained significant, controlling for extraversion and neuroticism.

  8. “His” and “Her” Marriage? The Role of Positive and Negative Marital Characteristics in Global Marital Satisfaction Among Older Adults

    PubMed Central

    Jopp, Daniela S.; Carr, Deborah; Sosinsky, Laura; Kim, Se-Kang

    2014-01-01

    Objectives. We explore gender differences in older adults’ appraisals of positive and negative aspects of their marriages, examine how these appraisals relate to global marital satisfaction, and identify distinctive marital profiles associated with global satisfaction in men and women. Method. Data are from the Changing Lives of Older Couples Study (n = 1,110). We used a variant of principal components analysis to generate marital quality profiles, based on one’s endorsement of positive and negative marital characteristics. OLS regression was used to detect associations between marital profiles and global marital satisfaction. Results. Men offered more positive marital assessments than women, particularly on items reflecting positive treatment by one’s wife. Three marital quality profiles emerged: Positive, Positive–Negative, and Negative. Although marital satisfaction was best explained by positive appraisals in both genders, they were less important for men than for women. The negative profile showed a tendency for a stronger prediction in men. Discussion. Prior studies show small differences in men’s and women’s global marital satisfaction. Our work provides evidence that the presence and magnitude of such gender differences may vary based on the specific marital component considered. We discuss ways that gender shapes marital interactions, expectations, and perceptions, and the implications of our results for the well-being of married older adults. PMID:24742399

  9. 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

  10. 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.

  11. Time-location analysis for exposure assessment studies of children using a novel global positioning system instrument.

    PubMed

    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.

  12. 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.

  13. 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

  14. Measurement of walking distance and speed in patients with peripheral arterial disease: a novel method using a global positioning system.

    PubMed

    Le Faucheur, Alexis; Abraham, Pierre; Jaquinandi, Vincent; Bouyé, Philippe; Saumet, Jean Louis; Noury-Desvaux, Bénédicte

    2008-02-19

    The maximal walking distance (MWD) performed on a treadmill test remains the "gold standard" in estimating the walking capacity of patients who have peripheral arterial disease with intermittent claudication, although treadmills are not accessible to most physicians. We hypothesized that global positioning system (GPS) recordings could monitor community-based outdoor walking and provide valid information on walking capacity in patients with peripheral arterial disease. We studied 24 patients (6 women) with arterial claudication (median [25th to 75th percentile] values: 57 years old [48 to 67 years], 169 cm tall [164 to 172 cm], weight 81 kg [71 to 86 kg], and ankle-brachial index 0.64 [0.56 to 0.74]). MWD on the treadmill was 184 m (144 to 246 m), which was compared with the results of self-reported MWD, the distance score from the Walking Impairment Questionnaire, MWD observed during a 6-minute walking test, and MWD measured over a GPS-recorded unconstrained outdoor walk in a public park. Self-reported MWD, Walking Impairment Questionnaire distance score, 6-minute walking test score, and GPS-measured MWD were 300 m (163 to 500 m), 28% (15% to 47%), 405 m (338 to 441 m), and 609 m (283 to 1287 m), respectively. The best correlation with MWD on the treadmill test was obtained with the MWD measured by the GPS (Spearman r=0.81, P<0.001). Outdoor walking capacity measured by a low-cost GPS is a potentially innovative way to study the walking capacity of patients with peripheral arterial disease. It opens new perspectives in the study of walking capacity for vascular patients with claudication under free-living conditions or for physicians who do not have a treadmill.

  15. 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.

  16. 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

  17. 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.

  18. Metabolic Power Method: Underestimation of Energy Expenditure in Field-Sport Movements Using a Global Positioning System Tracking System.

    PubMed

    Brown, Darcy M; Dwyer, Dan B; Robertson, Samuel J; Gastin, Paul B

    2016-11-01

    The purpose of this study was to assess the validity of a global positioning system (GPS) tracking system to estimate energy expenditure (EE) during exercise and field-sport locomotor movements. Twenty-seven participants each completed a 90-min exercise session on an outdoor synthetic futsal pitch. During the exercise session, they wore a 5-Hz GPS unit interpolated to 15 Hz and a portable gas analyzer that acted as the criterion measure of EE. The exercise session was composed of alternating 5-minute exercise bouts of randomized walking, jogging, running, or a field-sport circuit (×3) followed by 10 min of recovery. One-way analysis of variance showed significant (P < .01) and very large underestimations between GPS metabolic power- derived EE and oxygen-consumption (VO2) -derived EE for all field-sport circuits (% difference ≈ -44%). No differences in EE were observed for the jog (7.8%) and run (4.8%), whereas very large overestimations were found for the walk (43.0%). The GPS metabolic power EE over the entire 90-min session was significantly lower (P < .01) than the VO2 EE, resulting in a moderate underestimation overall (-19%). The results of this study suggest that a GPS tracking system using the metabolic power model of EE does not accurately estimate EE in field-sport movements or over an exercise session consisting of mixed locomotor activities interspersed with recovery periods; however, is it able to provide a reasonably accurate estimation of EE during continuous jogging and running.

  19. Estimation of crustal movements using the Global Positioning System (GPS) measurements along Nile Valley area, Egypt from 2007 to 2012

    NASA Astrophysics Data System (ADS)

    Sakr, Kamal; Radwan, Ali M.; Rashwan, Mohamed; Gomaa, Mahmoud

    2015-06-01

    The Nile Valley in Egypt is located to the west of the Red Sea Rift and to the south of the Mediterranean Sea. Recently, some moderate earthquakes were occurred along the Nile Valley at the eastern and western side. Tectonically, the Nile Valley is controlled by NW-SE, NE-SW, E-W and N-S tectonic trends due to the exerted forces and stresses. A program of studying the recent crustal movements in Egypt has been started since 1984 to cover some areas which are characterized by the occurrence of felt Earthquakes. One of these areas is the Nile Valley. About 6 moderate earthquakes with magnitudes more than 4 were occurred on both sides of River Nile. The present study aimed to determine the recent crustal movement parameters along the Nile Valley using the Global Positioning System (GPS) measurements. To achieve this mission, a GPS network consisting of ten geodetic stations has been established on both sides along the Nile Valley area. GPS measurements have been collected from 2007 to 2012. The collected data were processed using Bernese 5.0 Software. The result of the data analysis indicates that the rate of local velocity is small ranging from 1 to 4 mm/year. This rate is consistent with the low rate of occurrence of recent earthquakes activity along the Nile Valley area. But, the results obtained from the calculation of the regional velocity indicated that the velocity of the GPS stations including the African Plate motion is about 25 mm/year in the northeast direction which is consistent with the African Plate motion direction.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. The use of global positional satellite location in dementia: a feasibility study for a randomised controlled trial.

    PubMed

    Milne, Heather; van der Pol, Marjon; McCloughan, Lucy; Hanley, Janet; Mead, Gillian; Starr, John; Sheikh, Aziz; McKinstry, Brian

    2014-05-30

    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). 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. 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. Our data suggest that a RCT

  5. 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

  6. 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…

  7. 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…

  8. Global Positioning System (GPS) and Geographic Information System (GIS) analysis of mobile harvesting equipment and sediment delivery to streams during forest harvest operations on steep terrain: Experimental design

    Treesearch

    Daniel Bowker; Jeff Stringer; Chris Barton; Songlin. Fei

    2011-01-01

    Sediment mobilized by forest harvest machine traffic contributes substantially to the degradation of headwater stream systems. This study monitored forest harvest machine traffic to analyze how it affects sediment delivery to stream channels. Harvest machines were outfitted with global positioning system (GPS) dataloggers, recording machine movements and working status...

  9. 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

  10. 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

  11. Can positive matrix factorization help to understand patterns of organic trace gases at the continental Global Atmosphere Watch site Hohenpeissenberg?

    NASA Astrophysics Data System (ADS)

    Leuchner, M.; Gubo, S.; Schunk, C.; Wastl, C.; Kirchner, M.; Menzel, A.; Plass-Dülmer, C.

    2015-02-01

    From the rural Global Atmosphere Watch (GAW) site Hohenpeissenberg in the pre-alpine area of southern Germany, a data set of 24 C2-C8 non-methane hydrocarbons over a period of 7 years was analyzed. Receptor modeling was performed by positive matrix factorization (PMF) and the resulting factors were interpreted with respect to source profiles and photochemical aging. Differing from other studies, no direct source attribution was intended because, due to chemistry along transport, mass conservation from source to receptor is not given. However, at remote sites such as Hohenpeissenberg, the observed patterns of non-methane hydrocarbons can be derived from combinations of factors determined by PMF. A six-factor solution showed high stability and the most plausible results. In addition to a biogenic and a background factor of very stable compounds, four additional anthropogenic factors were resolved that could be divided into two short- and two long-lived patterns from evaporative sources/natural gas leakage and incomplete combustion processes. The volume or mass contribution at the site over the entire period was, in decreasing order, from the following factor categories: background, gas leakage and long-lived evaporative, residential heating and long-lived combustion, short-lived evaporative, short-lived combustion, and biogenic. The importance with respect to reactivity contribution was generally in reverse order, with the biogenic and the short-lived combustion factors contributing most. The seasonality of the factors was analyzed and compared to results of a simple box model using constant emissions and the photochemical decay calculated from the measured annual cycles of OH radicals and ozone. Two of the factors, short-lived combustion and gas leakage/long-lived evaporative, showed winter/summer ratios of about 9 and 7, respectively, as expected from constant source estimations. Contrarily, the short-lived evaporative emissions were about 3 times higher in summer

  12. 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.

  13. Mapping Tomorrow's Resources: A symposium on the uses of remote sensing, Geographic Information Systems (GIS), and Global Positioning Systems (GPS) for natural resources management

    SciTech Connect

    Falconer, A.

    1993-01-01

    The College of Natural Resources recognizes the important role it has in educating natural resources managers and leaders who can provide the guidance and knowledge needed to increase the production of the earth's renewable resources while sustaining and enhancing the global environment and the natural resource base. The College's teaching, research, extension, and service efforts focus on the many aspects of sustained multiple-natural-resources management and their relationship to man. Through its many programs, the College of Natural Resources focuses on solving local, state, national, and global problems to enhance a more efficient and contemporary use of the world's natural resources. Natural Resources and Environmental Issues (NREI) which began publication in 1993, is a technical series that addresses current topics relevant to natural resources and to the environment. The journal is published as a series of volumes, with at least one being issued each year as the proceedings of the Natural Resources Week Symposium. In the issue on Mapping Tommorrow's Resources, the following topics are discussed: Natural Resource Information from Monopoly to Competition; Global Resources and Mission to Planet Earth; Geographic Information Systems (GIS) Systems and Data Management for Global Data Sets in Natural Resources; the Global Resource Information Database; Overview of GIS Technology in Utah State Government; Politically Correct Global Mapping and Monitoring; Integrating Satellite Imagery and GIS into Natural Resources Management; Forest Service Applications of Remote Sensing and the National Training Program; the Position of the Global Positioning System (GPS) in Wildlife and Habitat Mapping; and the Bureau of Land Management's (BLM's) Remote Sensing Program in Utah.

  14. 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…

  15. 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…

  16. Choosing a survey sample when data on the population are limited: a method using Global Positioning Systems and aerial and satellite photographs.

    PubMed

    Shannon, Harry S; Hutson, Royce; Kolbe, Athena; Stringer, Bernadette; Haines, Ted

    2012-09-11

    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. 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. 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.

  17. 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.

  18. 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

  19. Antimicrobial susceptibility among Gram-positive organisms collected from pediatric patients globally between 2004 and 2011: results from the Tigecycline Evaluation and Surveillance Trial.

    PubMed

    Brandon, Michael; Dowzicky, Michael J

    2013-07-01

    The Tigecycline Evaluation and Surveillance Trial (TEST) was designed to monitor global longitudinal changes in bacterial susceptibility to a panel of antimicrobial agents, including tigecycline. In this study, we examine susceptibility among Gram-positive isolates collected from pediatric patients globally between 2004 and 2011. A total of 9,422 Gram-positive isolates were contributed by 1,255 centers, predominantly from Europe and North America. One-third of Staphylococcus aureus isolates were methicillin resistant, peaking in prevalence in 2007. All S. aureus isolates (n = 3,614) were susceptible to linezolid, tigecycline, and vancomycin; minocycline, imipenem, and meropenem were also highly active (>92% susceptibility). Ampicillin and penicillin susceptibility increased significantly during the study period (P < 0.0001 for both). Streptococcus pneumoniae isolates (n = 3,373) were highly susceptible to vancomycin (100%), linezolid (>99%), and levofloxacin and tigecycline (both >96%); imipenem susceptibility was low (32%) in Africa while minocycline susceptibility was low in Asia-Pacific Rim (38%). Penicillin resistance occurred in one-fifth of all S. pneumoniae isolates, with penicillin susceptibility ranging from 14% in Africa to 65% in Europe. Streptococcus agalactiae isolates (n = 1,056) were highly susceptible to most antimicrobials, although only 16% were susceptible to minocycline. Enterococcus faecalis isolates (n = 1,112) were highly susceptible (>97%) to ampicillin, linezolid, penicillin, tigecycline, and vancomycin globally, but only 34% were minocycline susceptible; minocycline susceptibility decreased significantly from 2004 to 2011 (P < 0.001). Tigecycline and linezolid were highly active against Enterococcus faecium (n = 267) globally (100% and 98% susceptible, respectively). Tigecycline and linezolid were highly active against Gram-positive pathogens from pediatric patients in TEST 2004 to 2011, with vancomycin and the carbapenems performing well

  20. Examination of the Locus of Positional Effects on Children's Production of Plural -s: Considerations From Local and Global Speech Planning.

    PubMed

    Theodore, Rachel M; Demuth, Katherine; Shattuck-Hufnagel, Stefanie

    2015-06-01

    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 investigations of plural -s, utterance-medial plurals were followed by a stop consonant (e.g., dogsbark), inducing high articulatory complexity. We examined whether the positional effect would be observed if the utterance-medial context were simplified to a following vowel. An elicited imitation task was used to collect productions of plural nouns from 2-year-old children. Nouns were elicited utterance-medially and utterance-finally, with the medial plural followed by either a stressed or an unstressed vowel. Acoustic analysis was used to identify evidence of morpheme production. The positional effect was absent when the morpheme was followed by a vowel (e.g., dogseat). However, it returned when the vowel-initial word contained 2 syllables (e.g., dogsarrive), suggesting that the increased processing load in the latter condition negated the facilitative effect of the easy articulatory context. Children's productions of grammatical morphemes reflect a rich interaction between emerging levels of linguistic competence, raising considerations for diagnosis and rehabilitation of language disorders.