Earth rotation excitation mechanisms derived from geodetic space observations

Science.gov (United States)

Göttl, F.; Schmidt, M.

2009-04-01

Earth rotation variations are caused by mass displacements and motions in the subsystems of the Earth. Via the satellite Gravity and Climate Experiment (GRACE) gravity field variations can be identified which are caused by mass redistribution in the Earth system. Therefore time variable gravity field models (GFZ RL04, CSR RL04, JPL RL04, ITG-Grace03, GRGS, ...) can be used to derive different impacts on Earth rotation. Furthermore satellite altimetry provides accurate information on sea level anomalies (AVISO, DGFI) which are caused by mass and volume changes of seawater. Since Earth rotation is solely affected by mass variations and motions the volume (steric) effect has to be reduced from the altimetric observations in order to infer oceanic contributions to Earth rotation variations. Therefore the steric effect is estimated from physical ocean parameters such as temperature and salinity changes in the oceans (WOA05, Ishii). In this study specific individual geophysical contributions to Earth rotation variations are identified by means of a multitude of accurate geodetic space observations in combination with a realistic error propagation. It will be shown that due to adjustment of altimetric and/or gravimetric solutions the results for polar motion excitations can be improved.

National Geodetic Survey (NGS) Geodetic Control Stations, (Horizontal and/or Vertical Control), March 2009

Data.gov (United States)

Earth Data Analysis Center, University of New Mexico — This data contains a set of geodetic control stations maintained by the National Geodetic Survey. Each geodetic control station in this dataset has either a precise...

Interseismic and coseismic surface deformation deduced from space geodetic observations : with inferences on seismic hazard, tectonic processes, earthquake complexity, and slip distribution

NARCIS (Netherlands)

Bos, A.G. (Annemarie Gerredina)

2003-01-01

In this thesis I am concerned with modeling the kinematics of surface deformation using space geodetic observations in order to advance insight in both interseismic and coseismic surface response. To model the surface deformation field I adopt the method of Spakman and Nyst (2002) which resolves the

National Geodetic Control Stations, Geographic NAD83, NGS (2004) [geodetic_ctrl_point_la_NGS_2004

Data.gov (United States)

Louisiana Geographic Information Center — This data contains a set of geodetic control stations maintained by the National Geodetic Survey. Each geodetic control station in this dataset has either a precise...

Current status of the EPOS WG4 - GNSS and Other Geodetic Data

Science.gov (United States)

Fernandes, Rui; Bastos, Luisa; Bruyninx, Carine; D'Agostino, Nicola; Dousa, Jan; Ganas, Athanassios; Lidberg, Martin; Nocquet, Jean-Mathieu

2014-05-01

WG4 - "EPOS Geodetic Data and Other Geodetic Data" is the Working Group of the EPOS project in charge of defining and preparing the integration of the existing Pan-European Geodetic Infrastructures that will support European Geosciences, which is the ultimate goal of the EPOS project. The WG4 is formed by representatives of the participating EPOS countries (23) but it is also open to the entire geodetic community. In fact, WG4 also already includes members from countries that formally are not integrating EPOS in this first step. The geodetic component of EPOS (WG4) is dealing essentially with Research Infrastructures focused on continuous operating GNSS (cGNSS) in the current phase. The option of concentrating the efforts on the presently most generalized geodetic tool supporting research on Solid Earth was decided in order to optimize the existing resources. Nevertheless, WG4 will continue to pursue the development of tools and methodologies that permit the access of the EPOS community to other geodetic information (e.g., gravimetry). Furthermore, although the focus is on Solid Earth applications, other research and technical applications (e.g., reference frames, meteorology, space weather) can also benefit from the efforts of WG4 EPOS towards the optimization of the geodetic resources in Europe. We will present and discuss the plans for the implementation of the thematic and core services (TCS) for geodetic data within EPOS and the related business plan. We will focus on strategies towards the implementation of the best solutions that will permit to the end-users, and in particular geo-scientists, to access the geodetic data, derived solutions, and associated metadata using transparent and uniform processes. Five pillars have been defined proposed for the TCS: Dissemination, Preservation, Monitoring, and Analysis of geodetic data plus the Support and Governance Infrastructure. Current proposals and remaining open questions will be discussed.

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

Science.gov (United States)

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.

Application of space geodetic techniques for the determination of intraplate deformations and movements in relation with the postglacial rebound of Fennoscandia

Energy Technology Data Exchange (ETDEWEB)

Scherneck, H G; Johansson, J M; Elgered, G [Chalmers Univ. of Technology, Goeteborg (Sweden). Onsala Space Observatory

1996-04-01

This report introduces into space geodetic measurements of relative positions over distances ranging from tens to thousands of kilometers. Such measurements can routinely be carried out with repeatabilities on the order of a few millimeters. The techniques presented are Very Long Baseline Interferometry (VLBI), employing observations of radio-astronomical objects in the distant universe, and ranging measurements to satellites of the GPS, the Global Positioning System. These techniques have helped to trace plate tectonic motions. More recently, deformations within continents have been detected. We present the SWEPOS system of permanently operating GPS stations as one of the major geoscience investments starting in 1993. BIFROST (Baseline Interference for Fennoscandian Rebound Observations, Sea level, and Tectonics) is a project within SWEPOS with main purpose to detect crustal movements in Fennoscandia. First results are presented, indicating movements which generally support the notion of a dominating displacement pattern due to the postglacial rebound of Fennoscandia. However deviations exist. densification is indicated in those areas which are notable for an increased seismicity. 148 refs.

Application of space geodetic techniques for the determination of intraplate deformations and movements in relation with the postglacial rebound of Fennoscandia

International Nuclear Information System (INIS)

Scherneck, H.G.; Johansson, J.M.; Elgered, G.

1996-04-01

This report introduces into space geodetic measurements of relative positions over distances ranging from tens to thousands of kilometers. Such measurements can routinely be carried out with repeatabilities on the order of a few millimeters. The techniques presented are Very Long Baseline Interferometry (VLBI), employing observations of radio-astronomical objects in the distant universe, and ranging measurements to satellites of the GPS, the Global Positioning System. These techniques have helped to trace plate tectonic motions. More recently, deformations within continents have been detected. We present the SWEPOS system of permanently operating GPS stations as one of the major geoscience investments starting in 1993. BIFROST (Baseline Interference for Fennoscandian Rebound Observations, Sea level, and Tectonics) is a project within SWEPOS with main purpose to detect crustal movements in Fennoscandia. First results are presented, indicating movements which generally support the notion of a dominating displacement pattern due to the postglacial rebound of Fennoscandia. However deviations exist. densification is indicated in those areas which are notable for an increased seismicity. 148 refs

Geodetic Control Information on Passive Marks: Horizontal and Vertical Geodetic Control Data for the United States - National Geospatial Data Asset (NGDA) Geodetic Control Information on Passive Marks

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This data contains a set of geodetic control stations maintained by the National Geodetic Survey. Each geodetic control station in this dataset has either a precise...

A new velocity field for Africa from combined GPS and DORIS space geodetic Solutions: Contribution to the definition of the African reference frame (AFREF)

Science.gov (United States)

Saria, E.; Calais, E.; Altamimi, Z.; Willis, P.; Farah, H.

2013-04-01

We analyzed 16 years of GPS and 17 years of Doppler orbitography and radiopositioning integrated by satellite (DORIS) data at continuously operating geodetic sites in Africa and surroundings to describe the present-day kinematics of the Nubian and Somalian plates and constrain relative motions across the East African Rift. The resulting velocity field describes horizontal and vertical motion at 133 GPS sites and 9 DORIS sites. Horizontal velocities at sites located on stable Nubia fit a single plate model with a weighted root mean square residual of 0.6 mm/yr (maximum residual 1 mm/yr), an upper bound for plate-wide motions and for regional-scale deformation in the seismically active southern Africa and Cameroon volcanic line. We confirm significant southward motion ( ˜ 1.5 mm/yr) in Morocco with respect to Nubia, consistent with earlier findings. We propose an updated angular velocity for the divergence between Nubia and Somalia, which provides the kinematic boundary conditions to rifting in East Africa. We update a plate motion model for the East African Rift and revise the counterclockwise rotation of the Victoria plate and clockwise rotation of the Rovuma plate with respect to Nubia. Vertical velocities range from - 2 to +2 mm/yr, close to their uncertainties, with no clear geographic pattern. This study provides the first continent-wide position/velocity solution for Africa, expressed in International Terrestrial Reference Frame (ITRF2008), a contribution to the upcoming African Reference Frame (AFREF). Except for a few regions, the African continent remains largely under-sampled by continuous space geodetic data. Efforts are needed to augment the geodetic infrastructure and openly share existing data sets so that the objectives of AFREF can be fully reached.

Geodynamical behavior of some active area in Egypt, as deduced from geodetic and gravity data

Science.gov (United States)

Issawy, E.; Mrlina, J.; Radwan, A.; Mahmoud, S.; Rayan, A.

2009-04-01

Temporal gravity variation in parallel with the space geodetic technique (GPS) had been started in Egypt for real campaigns in 1997. The geodetic networks around the High Dam, Aswan area was the first net to be measured. More than five measurement epochs were performed. The results had a considerable limit of coincidence between gravity and GPS observations. The trend of gravity changes indicated a positive stress and had the vertical displacement observed for leveling points. The lowest gravity changes along Kalabsha fault reflect extensional and/or strike component of the stress field. Also, the areas around Cairo (Greater Cairo) and due to the occurrence of an earthquake of 1992, such type of measurements were useful for monitoring the recent activity. The data of the geodetic network around Cairo after 5 campaigns showed that, the estimated horizontal velocities for almost all points are 5.5± mm/year in approximately NW-SE direction. The non-tidal changes can explain the dynamic process within the upper crust related to the development of local stress conditions. The trends of gravity changes are more or less coincident with that deduced from GPS deformation analysis and the occurrence of the main shocks in the area. In additions, in 2005 the geodetic network around the southern part of Sinai and the Gulf of Suez were established. One campaign of measurements had been performed and the gravity values were obtained.

Geodetic Volcano Monitoring Research in Canary Islands: Recent Results

Science.gov (United States)

Fernandez, J.; Gonzalez, P. J.; Arjona, A.; Camacho, A. G.; Prieto, J. F.; Seco, A.; Tizzani, P.; Manzo, M. R.; Lanari, R.; Blanco, P.; Mallorqui, J. J.

2009-05-01

The Canarian Archipelago is an oceanic island volcanic chain with a long-standing history of volcanic activity (> 40 Ma). It is located off the NW coast of the African continent, lying over a transitional crust of the Atlantic African passive margin. At least 12 eruptions have been occurred on the islands of Lanzarote, Tenerife and La Palma in the last 500 years. Volcanism manifest predominantly as basaltic strombolian monogenetic activity (whole archipelago) and central felsic volcanism (active only in Tenerife Island). We concentrate our studies in the two most active islands, Tenerife and La Palma. In these islands, we tested different methodologies of geodetic monitoring systems. We use a combination of ground- and space-based techniques. At Tenerife Island, a differential interferometric study was performed to detect areas of deformation. DInSAR detected two clear areas of deformation, using this results a survey-based GPS network was designed and optimized to control those deformations and the rest of the island. Finally, using SBAS DInSAR results weak spatial long- wavelength subsidence signals has been detected. At La Palma, the first DInSAR analysis have not shown any clear deformation, so a first time series analysis was performed detecting a clear subsidence signal at Teneguia volcano, as for Tenerife a GPS network was designed and optimized taking into account stable and deforming areas. After several years of activities, geodetic results served to study ground deformations caused by a wide variety of sources, such as changes in groundwater levels, volcanic activity, volcano-tectonics, gravitational loading, etc. These results proof that a combination of ground-based and space-based techniques is suitable tool for geodetic volcano monitoring in Canary Islands. Finally, we would like to strength that those results could have serious implications on the continuous geodetic monitoring system design and implementation for the Canary Islands which is under

Geodetic Survey Water Level Observations

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Over one million images of National Coast & Geodetic Survey (now NOAA's National Geodetic Survey/NGS) forms captured from microfiche. Tabular forms and charts...

Geodetic refraction effects of electromagnetic wave propagation through the atmosphere

CERN Document Server

1984-01-01

With very few exceptions, geodetic measurements use electro­ magnetic radiation in order to measure directions, distances, time delays, and Doppler frequency shifts, to name the main ter­ restrial and space observables. Depending on the wavelength of the radiation and the purpose of the measurements, the follow­ ing parameters of the electromagnetic wave are measured: ampli­ tude, phase, angle-of-arrival, polarisation and frequency. Ac­ curate corrections have to be applied to the measurements in order to take into account the effects of the intervening medium between transmitter and receiver. The known solutions use at­ mospheric models, special observation programs, remote sensing techniques and instrumental methods. It has been shown that the effects of the earth's atmospheric envelope present a fundamental limitation to the accuracy and precision of geodetic measurements. This applies equally to ter­ restrial and space applications. Instrumental accuracies are al­ ready below the atmospherically i...

NASA's Contribution to Global Space Geodesy Networks

Science.gov (United States)

Bosworth, John M.

1999-01-01

The NASA Space Geodesy program continues to be a major provider of space geodetic data for the international earth science community. NASA operates high performance Satellite Laser Ranging (SLR), Very Long Baseline Interferometry (VLBI) and Global Positioning System (GPS) ground receivers at well over 30 locations around the world and works in close cooperation with space geodetic observatories around the world. NASA has also always been at the forefront in the quest for technical improvement and innovation in the space geodesy technologies to make them even more productive, accurate and economical. This presentation will highlight the current status of NASA's networks; the plans for partnerships with international groups in the southern hemisphere to improve the geographic distribution of space geodesy sites and the status of the technological improvements in SLR and VLBI that will support the new scientific thrusts proposed by interdisciplinary earth scientists. In addition, the expanding role of the NASA Space geodesy data archive, the CDDIS will be described.

Global Positioning System (GPS) survey of Augustine Volcano, Alaska, August 3-8, 2000: data processing, geodetic coordinates and comparison with prior geodetic surveys

Science.gov (United States)

Pauk, Benjamin A.; Power, John A.; Lisowski, Mike; Dzurisin, Daniel; Iwatsubo, Eugene Y.; Melbourne, Tim

2001-01-01

Between August 3 and 8,2000,the Alaska Volcano Observatory completed a Global Positioning System (GPS) survey at Augustine Volcano, Alaska. Augustine is a frequently active calcalkaline volcano located in the lower portion of Cook Inlet (fig. 1), with reported eruptions in 1812, 1882, 1909?, 1935, 1964, 1976, and 1986 (Miller et al., 1998). Geodetic measurements using electronic and optical surveying techniques (EDM and theodolite) were begun at Augustine Volcano in 1986. In 1988 and 1989, an island-wide trilateration network comprising 19 benchmarks was completed and measured in its entirety (Power and Iwatsubo, 1998). Partial GPS surveys of the Augustine Island geodetic network were completed in 1992 and 1995; however, neither of these surveys included all marks on the island.Additional GPS measurements of benchmarks A5 and A15 (fig. 2) were made during the summers of 1992, 1993, 1994, and 1996. The goals of the 2000 GPS survey were to:1) re-measure all existing benchmarks on Augustine Island using a homogeneous set of GPS equipment operated in a consistent manner, 2) add measurements at benchmarks on the western shore of Cook Inlet at distances of 15 to 25 km, 3) add measurements at an existing benchmark (BURR) on Augustine Island that was not previously surveyed, and 4) add additional marks in areas of the island thought to be actively deforming. The entire survey resulted in collection of GPS data at a total of 24 sites (fig. 1 and 2). In this report we describe the methods of GPS data collection and processing used at Augustine during the 2000 survey. We use this data to calculate coordinates and elevations for all 24 sites surveyed. Data from the 2000 survey is then compared toelectronic and optical measurements made in 1988 and 1989. This report also contains a general description of all marks surveyed in 2000 and photographs of all new marks established during the 2000 survey (Appendix A).

Seismology and space-based geodesy

Science.gov (United States)

Tralli, David M.; Tajima, Fumiko

1993-01-01

The potential of space-based geodetic measurement of crustal deformation in the context of seismology is explored. The achievements of seismological source theory and data analyses, mechanical modeling of fault zone behavior, and advances in space-based geodesy are reviewed, with emphasis on realizable contributions of space-based geodetic measurements specifically to seismology. The fundamental relationships between crustal deformation associated with an earthquake and the geodetically observable data are summarized. The response and spatial and temporal resolution of the geodetic data necessary to understand deformation at various phases of the earthquake cycle is stressed. The use of VLBI, SLR, and GPS measurements for studying global geodynamics properties that can be investigated to some extent with seismic data is discussed. The potential contributions of continuously operating strain monitoring networks and globally distributed geodetic observatories to existing worldwide modern digital seismographic networks are evaluated in reference to mutually addressable problems in seismology, geophysics, and tectonics.

National Geodetic Survey's Airport Aerial Photography

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The National Geodetic Survey (NGS), formerly part of the U.S. Coast and Geodetic Survey, has been performing Aeronautical surveys since the 1920's. NGS, in...

Misbheaving Faults: The Expanding Role of Geodetic Imaging in Unraveling Unexpected Fault Slip Behavior

Science.gov (United States)

Barnhart, W. D.; Briggs, R.

2015-12-01

Geodetic imaging techniques enable researchers to "see" details of fault rupture that cannot be captured by complementary tools such as seismology and field studies, thus providing increasingly detailed information about surface strain, slip kinematics, and how an earthquake may be transcribed into the geological record. For example, the recent Haiti, Sierra El Mayor, and Nepal earthquakes illustrate the fundamental role of geodetic observations in recording blind ruptures where purely geological and seismological studies provided incomplete views of rupture kinematics. Traditional earthquake hazard analyses typically rely on sparse paleoseismic observations and incomplete mapping, simple assumptions of slip kinematics from Andersonian faulting, and earthquake analogs to characterize the probabilities of forthcoming ruptures and the severity of ground accelerations. Spatially dense geodetic observations in turn help to identify where these prevailing assumptions regarding fault behavior break down and highlight new and unexpected kinematic slip behavior. Here, we focus on three key contributions of space geodetic observations to the analysis of co-seismic deformation: identifying near-surface co-seismic slip where no easily recognized fault rupture exists; discerning non-Andersonian faulting styles; and quantifying distributed, off-fault deformation. The 2013 Balochistan strike slip earthquake in Pakistan illuminates how space geodesy precisely images non-Andersonian behavior and off-fault deformation. Through analysis of high-resolution optical imagery and DEMs, evidence emerges that a single fault map slip as both a strike slip and dip slip fault across multiple seismic cycles. These observations likewise enable us to quantify on-fault deformation, which account for ~72% of the displacements in this earthquake. Nonetheless, the spatial distribution of on- and off-fault deformation in this event is highly spatially variable- a complicating factor for comparisons

Time Biases in laser ranging measurements; impacts on geodetic products (Reference Frame and Orbitography)

Science.gov (United States)

Belli, A.; Exertier, P.; Lemoine, F. G.; Chinn, D. S.; Zelensky, N. P.

2017-12-01

The GGOS objectives are to maintain a geodetic network with an accuracy of 1 mm and a stability of 0.1 mm per year. For years, the laser ranging technique, which provide very accurate absolute distances to geodetic targets enable to determine the scale factor as well as coordinates of the geocenter. In order to achieve this goal, systematic errors appearing in the laser ranging measurements must be considered and solved. In addition to Range Bias (RB), which is the primary source of uncertainty of the technique, Time Bias (TB) has been recently detected by using the Time Transfer by Laser Link (T2L2) space instrument capability on-board the satellite Jason-2. Instead of determining TB through the precise orbit determination that is applied to commonly used geodetic targets like LAGEOS to estimate global geodetic products, we have developed, independently, a dedicated method to transfer time between remote satellite laser ranging stations. As a result, the evolving clock phase shift to UTC of around 30 stations has been determined under the form of time series of time bias per station from 2008 to 2016 with an accuracy of 3-4 ns. It demonstrated the difficulty, in terms of Time & Frequency used technologies, to locally maintain accuracy and long term stability at least in the range of 100 ns that is the current requirement for time measurements (UTC) for the laser ranging technique. Because some laser ranging stations oftently exceed this limit (from 100 ns to a few μs) we have been studying these effects first on the precision orbit determination itself, second on the station positioning. We discuss the impact of TB on LAGEOS and Jason-2 orbits, which appears to affect the along-track component essentially. We also investigate the role of TB in global geodetic parameters as the station coordinates. Finally, we propose to provide the community with time series of time bias of laser ranging stations, under the form of a data- handling-file in order to be included in

Identifying and Allocating Geodetic Systems to historical oil gas wells by using high-resolution satellite imagery

Science.gov (United States)

Alvarez, Gabriel O.

2018-05-01

Hydrocarbon exploration in Argentina started long before the IGM created a single, high-precision geodetic reference network for the whole country. Several geodetic surveys were conducted in every producing basin, which have ever since then supported well placement. Currently, every basin has a huge amount of information referenced to the so-called "local" geodetic systems, such as Chos Malal - Quiñi Huao in the Neuquén Basin, and Pampa del Castillo in the San Jorge Basin, which differ to a greater or lesser extent from the national Campo Inchauspe datum established by the IGM in 1969 as the official geodetic network. However, technology development over the last few years and the expansion of satellite positioning systems such as GPS resulted in a new world geodetic order. Argentina rapidly joined this new geodetic order through the implementation of a new national geodetic system by the IGM: POSGAR network, which replaced the old national Campo Inchauspe system. However, this only helped to worsen the data georeferencing issue for oil companies, as a third reference system was added to each basin. Now every basin has a local system, the national system until 1997 (Campo Inchauspe), and finally the newly created POSGAR network national satellite system, which is geocentric unlike the former two planimetric datums. The purpose of this paper is to identify and allocate geodetic systems of coordinates to historical wells, whose geodetic system is missing or has been erroneously allocated, by using currently available technological resources such as geographic information systems and high-resolution satellite imagery.

Agile Big Data Analytics of High-Volume Geodetic Data Products for Improving Science and Hazard Response

Data.gov (United States)

National Aeronautics and Space Administration — Geodetic imaging is revolutionizing geophysics, but the scope of discovery has been limited by labor-intensive technological implementation of the analyses. The...

Three-dimensional stochastic adjustment of volcano geodetic network in Arenal volcano, Costa Rica

Science.gov (United States)

Muller, C.; van der Laat, R.; Cattin, P.-H.; Del Potro, R.

2009-04-01

Volcano geodetic networks are a key instrument to understanding magmatic processes and, thus, forecasting potentially hazardous activity. These networks are extensively used on volcanoes worldwide and generally comprise a number of different traditional and modern geodetic surveying techniques such as levelling, distances, triangulation and GNSS. However, in most cases, data from the different methodologies are surveyed, adjusted and analysed independently. Experience shows that the problem with this procedure is the mismatch between the excellent correlation of position values within a single technique and the low cross-correlation of such values within different techniques or when the same network is surveyed shortly after using the same technique. Moreover one different independent network for each geodetic surveying technique strongly increase logistics and thus the cost of each measurement campaign. It is therefore important to develop geodetic networks which combine the different geodetic surveying technique, and to adjust geodetic data together in order to better quantify the uncertainties associated to the measured displacements. In order to overcome the lack of inter-methodology data integration, the Geomatic Institute of the University of Applied Sciences of Western Switzerland (HEIG-VD) has developed a methodology which uses a 3D stochastic adjustment software of redundant geodetic networks, TRINET+. The methodology consists of using each geodetic measurement technique for its strengths relative to other methodologies. Also, the combination of the measurements in a single network allows more cost-effective surveying. The geodetic data are thereafter adjusted and analysed in the same referential frame. The adjustment methodology is based on the least mean square method and links the data with the geometry. Trinet+ also allows to run a priori simulations of the network, hence testing the quality and resolution to be expected for a determined network even

Space geodetic observations of repeating slow slip events beneath the Bonin Islands

Science.gov (United States)

Arisa, Deasy; Heki, Kosuke

2017-09-01

The Pacific Plate subducts beneath the Philippine Sea Plate along the Izu-Bonin Trench. We investigated crustal movements at the Bonin Islands, using Global Navigation Satellite System and geodetic Very Long Baseline Interferometry data to reveal how the two plates converge in this subduction zone. These islands are located ∼100 km from the trench, just at the middle between the volcanic arc and the trench, making these islands suitable for detecting signatures of episodic deformation such as slow slip events (SSEs). During 2007-2016, we found five SSEs repeating quasi-periodically with similar displacement patterns. In estimating their fault parameters, we assumed that the fault lies on the prescribed plate boundary, and optimized the size, shape and position of the fault and dislocation vectors. Average fault slip was ∼5 cm, and the average moment magnitude was ∼6.9. We also found one SSE occurred in 2008 updip of the repeating SSE in response to an M6 class interplate earthquake. In spite of the frequent occurrence of SSEs, there is no evidence for long-term strain accumulation in the Bonin Islands that may lead to future megathrust earthquakes. Plate convergence in Mariana-type subduction zones may occur, to a large extent, episodically as repeating SSEs.

Modified geodetic brane cosmology

International Nuclear Information System (INIS)

Cordero, Rubén; Cruz, Miguel; Molgado, Alberto; Rojas, Efraín

2012-01-01

We explore the cosmological implications provided by the geodetic brane gravity action corrected by an extrinsic curvature brane term, describing a codimension-1 brane embedded in a 5D fixed Minkowski spacetime. In the geodetic brane gravity action, we accommodate the correction term through a linear term in the extrinsic curvature swept out by the brane. We study the resulting geodetic-type equation of motion. Within a Friedmann–Robertson–Walker metric, we obtain a generalized Friedmann equation describing the associated cosmological evolution. We observe that, when the radiation-like energy contribution from the extra dimension is vanishing, this effective model leads to a self-(non-self)-accelerated expansion of the brane-like universe in dependence on the nature of the concomitant parameter β associated with the correction, which resembles an analogous behaviour in the DGP brane cosmology. Several possibilities in the description for the cosmic evolution of this model are embodied and characterized by the involved density parameters related in turn to the cosmological constant, the geometry characterizing the model, the introduced β parameter as well as the dark-like energy and the matter content on the brane. (paper)

An Autonomous, Low Cost Platform for Seafloor Geodetic Observations

Science.gov (United States)

Ericksen, T.; Foster, J. H.; Bingham, B. S.

2013-12-01

The high cost of acquiring geodetic data from the sea floor has limited the observations available to help us understand and model the behavior of seafloor geodetic processes. To address this problem, the Pacific GPS Facility at the University of Hawaii is developing a cost effective approach for accurately measuring short-term vertical motions of the seafloor and maintaining a continuous long-term record of seafloor pressure without the requirement for costly ship time. There is a recognized need to vastly increase our underwater geodetic observing capacity. Most of the largest recorded earthquakes and most devastating tsunamis are generated at subduction zones underwater. Similarly, many volcanoes are partly (e.g. Santorini) or completely (e.g. Loihi) submerged, and are not well observed and understood. Furthermore, landslide features ring many ocean basins, and huge debris deposits surround many volcanic oceanic islands. Our approach will lower the cost of collecting sea-floor geodetic data, reducing the barriers preventing us from acquiring the information we need to observe and understand these types of structures and provide a direct societal benefit in improving hazard assessment. The capability is being developed by equipping one of the University of Hawaii Wave Gliders with an integrated acoustic telemetry package, a dual frequency geodetic-grade Global Positioning System (GPS) receiver, processing unit, and cellular communications. The Wave Glider will interrogate high accuracy pressure sensors on the sea floor to maintain a near-continuous stream of pressure and temperature data, but seafloor pressure data includes contribution from a variety of sources and on its own may not provide the accuracy required for geodetic investigations. Independent measurements of sea surface pressure and sea surface height can be used to remove these contributions from the observed sea floor pressure timeseries. We will integrate our seafloor pressure measurements with air

NASA's Next Generation Space Geodesy Network

Science.gov (United States)

Desai, S. D.; Gross, R. S.; Hilliard, L.; Lemoine, F. G.; Long, J. L.; Ma, C.; McGarry, J. F.; Merkowitz, S. M.; Murphy, D.; Noll, C. E.;

Next Generation NASA Initiative for Space Geodesy

Science.gov (United States)

Merkowitz, S. M.; Desai, S.; Gross, R. S.; Hilliard, L.; Lemoine, F. G.; Long, J. L.; Ma, C.; McGarry J. F.; Murphy, D.; Noll, C. E.;

Leveraging geodetic data to reduce losses from earthquakes

Science.gov (United States)

Murray, Jessica R.; Roeloffs, Evelyn A.; Brooks, Benjamin A.; Langbein, John O.; Leith, William S.; Minson, Sarah E.; Svarc, Jerry L.; Thatcher, Wayne R.

2018-04-23

Seismic hazard assessments that are based on a variety of data and the best available science, coupled with rapid synthesis of real-time information from continuous monitoring networks to guide post-earthquake response, form a solid foundation for effective earthquake loss reduction. With this in mind, the Earthquake Hazards Program (EHP) of the U.S. Geological Survey (USGS) Natural Hazards Mission Area (NHMA) engages in a variety of undertakings, both established and emergent, in order to provide high quality products that enable stakeholders to take action in advance of and in response to earthquakes. Examples include the National Seismic Hazard Model (NSHM), development of tools for improved situational awareness such as earthquake early warning (EEW) and operational earthquake forecasting (OEF), research about induced seismicity, and new efforts to advance comprehensive subduction zone science and monitoring. Geodetic observations provide unique and complementary information directly relevant to advancing many aspects of these efforts (fig. 1). EHP scientists have long leveraged geodetic data for a range of influential studies, and they continue to develop innovative observation and analysis methods that push the boundaries of the field of geodesy as applied to natural hazards research. Given the ongoing, rapid improvement in availability, variety, and precision of geodetic measurements, considering ways to fully utilize this observational resource for earthquake loss reduction is timely and essential. This report presents strategies, and the underlying scientific rationale, by which the EHP could achieve the following outcomes: The EHP is an authoritative source for the interpretation of geodetic data and its use for earthquake loss reduction throughout the United States and its territories.The USGS consistently provides timely, high quality geodetic data to stakeholders.Significant earthquakes are better characterized by incorporating geodetic data into USGS

Multi-geodetic characterization of the seasonal signal at the CERGA geodetic reference, France

Science.gov (United States)

Memin, A.; Viswanathan, V.; Fienga, A.; Santamaría-Gómez, A.; Boy, J. P.

2016-12-01

Crustal deformations due to surface-mass loading account for a significant part of the variability in geodetic time series. A perfect understanding of the loading signal observed by geodetic techniques should help in improving terrestrial reference frame (TRF) realizations. Yet, discrepancies between crustal motion estimates from models of surface-mass loading and observations are still too large so that no model is currently recommended by the IERS for reducing the data. We investigate the discrepancy observed in the seasonal variations of the CERGA station, South of France.We characterize the seasonal motions of the reference geodetic station CERGA from GNSS, SLR and LLR. We compare the station motion observed with GNSS and SLR and we estimate changes in the station-to-the-moon distance using an improved processing strategy. We investigate the consistency between these geodetic techniques and compare the observed station motion with that estimated using models of surface-mass change. In that regard, we compute atmospheric loading effects using surface pressure fields from ECMWF, assuming an ocean response according to the classical inverted barometer (IB) assumption, considered to be valid for periods typically exceeding a week. We also used general circulation ocean models (ECCO and GLORYS) forced by wind, heat and fresh water fluxes. The continental water storage is described using GLDAS/Noah and MERRA-land models.Using the surface-mass models, we estimate the amplitude of the seasonal vertical motion of the CERGA station ranging between 5 and 10 mm with a maximum reached in August, mostly due to hydrology. The horizontal seasonal motion of the station may reach up to 3 mm. Such a station motion should induce a change in the distance to the moon reaching up to 10 mm, large enough to be detected in LLR time series and compared to GNSS- and SLR-derived motion.

GOZCARDS Source Data for Temperature Monthly Zonal Averages on a Geodetic Latitude and Pressure Grid V1.00

Data.gov (United States)

National Aeronautics and Space Administration — The GOZCARDS Source Data for Temperature Monthly Zonal Averages on a Geodetic Latitude and Pressure Grid product (GozSmlpT) contains zonal means and related...

Added-value joint source modelling of seismic and geodetic data

Science.gov (United States)

Sudhaus, Henriette; Heimann, Sebastian; Walter, Thomas R.; Krueger, Frank

2013-04-01

In tectonically active regions earthquake source studies strongly support the analysis of the current faulting processes as they reveal the location and geometry of active faults, the average slip released or more. For source modelling of shallow, moderate to large earthquakes often a combination of geodetic (GPS, InSAR) and seismic data is used. A truly joint use of these data, however, usually takes place only on a higher modelling level, where some of the first-order characteristics (time, centroid location, fault orientation, moment) have been fixed already. These required basis model parameters have to be given, assumed or inferred in a previous, separate and highly non-linear modelling step using one of the these data sets alone. We present a new earthquake rupture model implementation that realizes a fully combined data integration of surface displacement measurements and seismic data in a non-linear optimization of simple but extended planar ruptures. The model implementation allows for fast forward calculations of full seismograms and surface deformation and therefore enables us to use Monte Carlo global search algorithms. Furthermore, we benefit from the complementary character of seismic and geodetic data, e. g. the high definition of the source location from geodetic data and the sensitivity of the resolution of the seismic data on moment releases at larger depth. These increased constraints from the combined dataset make optimizations efficient, even for larger model parameter spaces and with a very limited amount of a priori assumption on the source. A vital part of our approach is rigorous data weighting based on the empirically estimated data errors. We construct full data error variance-covariance matrices for geodetic data to account for correlated data noise and also weight the seismic data based on their signal-to-noise ratio. The estimation of the data errors and the fast forward modelling opens the door for Bayesian inferences of the source

Low degree Earth's gravity coefficients determined from different space geodetic observations and climate models

Science.gov (United States)

Wińska, Małgorzata; Nastula, Jolanta

2017-04-01

Large scale mass redistribution and its transport within the Earth system causes changes in the Earth's rotation in space, gravity field and Earth's ellipsoid shape. These changes are observed in the ΔC21, ΔS21, and ΔC20 spherical harmonics gravity coefficients, which are proportional to the mass load-induced Earth rotational excitations. In this study, linear trend, decadal, inter-annual, and seasonal variations of low degree spherical harmonics coefficients of Earth's gravity field, determined from different space geodetic techniques, Gravity Recovery and Climate Experiment (GRACE), satellite laser ranging (SLR), Global Navigation Satellite System (GNSS), Earth rotation, and climate models, are examined. In this way, the contribution of each measurement technique to interpreting the low degree surface mass density of the Earth is shown. Especially, we evaluate an usefulness of several climate models from the Coupled Model Intercomparison Project phase 5 (CMIP5) to determine the low degree Earth's gravity coefficients using GRACE satellite observations. To do that, Terrestrial Water Storage (TWS) changes from several CMIP5 climate models are determined and then these simulated data are compared with the GRACE observations. Spherical harmonics ΔC21, ΔS21, and ΔC20 changes are calculated as the sum of atmosphere and ocean mass effect (GAC values) taken from GRACE and a land surface hydrological estimate from the selected CMIP5 climate models. Low degree Stokes coefficients of the surface mass density determined from GRACE, SLR, GNSS, Earth rotation measurements and climate models are compared to each other in order to assess their consistency. The comparison is done by using different types of statistical and signal processing methods.

The combined geodetic network adjusted on the reference ellipsoid – a comparison of three functional models for GNSS observations

Directory of Open Access Journals (Sweden)

Kadaj Roman

2016-12-01

Full Text Available The adjustment problem of the so-called combined (hybrid, integrated network created with GNSS vectors and terrestrial observations has been the subject of many theoretical and applied works. The network adjustment in various mathematical spaces was considered: in the Cartesian geocentric system on a reference ellipsoid and on a mapping plane. For practical reasons, it often takes a geodetic coordinate system associated with the reference ellipsoid. In this case, the Cartesian GNSS vectors are converted, for example, into geodesic parameters (azimuth and length on the ellipsoid, but the simple form of converted pseudo-observations are the direct differences of the geodetic coordinates. Unfortunately, such an approach may be essentially distorted by a systematic error resulting from the position error of the GNSS vector, before its projection on the ellipsoid surface. In this paper, an analysis of the impact of this error on the determined measures of geometric ellipsoid elements, including the differences of geodetic coordinates or geodesic parameters is presented. Assuming that the adjustment of a combined network on the ellipsoid shows that the optimal functional approach in relation to the satellite observation, is to create the observational equations directly for the original GNSS Cartesian vector components, writing them directly as a function of the geodetic coordinates (in numerical applications, we use the linearized forms of observational equations with explicitly specified coefficients. While retaining the original character of the Cartesian vector, one avoids any systematic errors that may occur in the conversion of the original GNSS vectors to ellipsoid elements, for example the vector of the geodesic parameters. The problem is theoretically developed and numerically tested. An example of the adjustment of a subnet loaded from the database of reference stations of the ASG-EUPOS system was considered for the preferred functional

GOZCARDS Source Data for Ozone Monthly Zonal Means on a Geodetic Latitude and Pressure Grid V1.01

Data.gov (United States)

National Aeronautics and Space Administration — The GOZCARDS Source Data for Ozone Monthly Zonal Averages on a Geodetic Latitude and Pressure Grid product (GozSmlpO3) contains zonal means and related information...

GOZCARDS Merged Data for Ozone Monthly Zonal Means on a Geodetic Latitude and Pressure Grid V1.01

Data.gov (United States)

National Aeronautics and Space Administration — The GOZCARDS Merged Data for Ozone Monthly Zonal Averages on a Geodetic Latitude and Pressure Grid product (GozMmlpO3) contains zonal means and related information...

Space-geodetic Constraints on GIA Models with 3D Viscosity

Science.gov (United States)

Van Der Wal, W.; Xu, Z.

2012-12-01

Models for Glacial Isostatic Adjustment (GIA) are an important correction to observations of mass change in the polar regions. Inputs for GIA models include past ice thickness and deformation parameters of the Earth's mantle, both of which are imperfectly known. Here we focus on the latter by investigating GIA models with 3D viscosity and composite (linear and non-linear) flow laws. It was found recently that GIA models with a composite flow law result in a better fit to historic sea level data, but they predict too low present-day uplift rates and gravity rates. Here GIA models are fit to space-geodetic constraints in Fennoscandia and North America. The preferred models are used to calculate the magnitude of the GIA correction on mass change estimates in Greenland and Antarctica. The observations used are GRACE Release 4 solutions from CSR and GFZ and published GPS solutions for North America and Fennoscandia, as well as historic sea level data. The GIA simulations are performed with a finite element model of a spherical, self-gravitating, incompressible Earth with 2x2 degree elements. Parameters in the flow laws are taken from seismology, heatflow measurements and experimental constraints and the ice loading history is prescribed by ICE-5G. It was found that GRACE and GPS derived uplift rates agree at the level of 1 mm/year in North America and at a level of 0.5 mm/year in Fennoscandia, the difference between the two regions being due to larger GPS errors and under sampling in North America. It can be concluded that both GPS and GRACE see the same process and the effects of filtering, noise and non-GIA processes such as land hydrology are likely to be small. Two GIA models are found that bring present-day uplift rate close to observed values in North America and Fennoscandia. These models result in a GIA correction of -17 Gt/year and -26 Gt/year on Greenland mass balance estimates from GRACE.

GOZCARDS Merged Data for Hydrogen Chloride Monthly Zonal Means on a Geodetic Latitude and Pressure Grid V1.01

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National Aeronautics and Space Administration — The GOZCARDS Merged Data for Hydrogen Chloride Monthly Zonal Averages on a Geodetic Latitude and Pressure Grid product (GozMmlpHCl) contains zonal means and related...

GOZCARDS Source Data for Nitric Acid Monthly Zonal Means on a Geodetic Latitude and Pressure Grid V1.01

Data.gov (United States)

National Aeronautics and Space Administration — The GOZCARDS Source Data for Nitric Acid Monthly Zonal Averages on a Geodetic Latitude and Pressure Grid product (GozSmlpHNO3) contains zonal means and related...

GOZCARDS Merged Data for Nitric Acid Monthly Zonal Means on a Geodetic Latitude and Pressure Grid V1.01

Data.gov (United States)

National Aeronautics and Space Administration — The GOZCARDS Merged Data for Nitric Acid Monthly Zonal Averages on a Geodetic Latitude and Pressure Grid product (GozMmlpHNO3) contains zonal means and related...

GOZCARDS Source Data for Nitrous Oxide Monthly Zonal Means on a Geodetic Latitude and Pressure Grid V1.01

Data.gov (United States)

National Aeronautics and Space Administration — The GOZCARDS Source Data for Nitrous Oxide Monthly Zonal Averages on a Geodetic Latitude and Pressure Grid product (GozSmlpN2O) contains zonal means and related...

GOZCARDS Merged Data for Nitrous Oxide Monthly Zonal Means on a Geodetic Latitude and Pressure Grid V1.01

Data.gov (United States)

National Aeronautics and Space Administration — The GOZCARDS Merged Data for Nitrous Oxide Monthly Zonal Averages on a Geodetic Latitude and Pressure Grid product (GozMmlpN2O) contains zonal means and related...

GOZCARDS Merged Data for Water Vapor Monthly Zonal Means on a Geodetic Latitude and Pressure Grid V1.01

Data.gov (United States)

National Aeronautics and Space Administration — The GOZCARDS Merged Data for Water Vapor Monthly Zonal Averages on a Geodetic Latitude and Pressure Grid product (GozMmlpH2O) contains zonal means and related...

Geodetic achievement and avoidance games for graphs | Haynes ...

African Journals Online (AJOL)

Let G = (V,E) be a nontrivial connected graph. For a subset S ⊆ V, the geodesic closure (S) of S is the set of all vertices on geodesics (shortest paths) between two vertices of S. We study the geodetic achievement and avoidance games defined by Buckley and Harary (Geodetic games for graphs, Quaestiones Math.

The Morse oscillator in position space, momentum space, and phase space

DEFF Research Database (Denmark)

Dahl, Jens Peder; Springborg, Michael

1988-01-01

We present a unified description of the position-space wave functions, the momentum-space wave functions, and the phase-space Wigner functions for the bound states of a Morse oscillator. By comparing with the functions for the harmonic oscillator the effects of anharmonicity are visualized....... Analytical expressions for the wave functions and the phase space functions are given, and it is demonstrated how a numerical problem arising from the summation of an alternating series in evaluating Laguerre functions can be circumvented. The method is applicable also for other problems where Laguerre...... functions are to be calculated. The wave and phase space functions are displayed in a series of curves and contour diagrams. An Appendix discusses the calculation of the modified Bessel functions of real, positive argument and complex order, which is required for calculating the phase space functions...

The Global Geodetic Observing System: Recent Activities and Accomplishments

Science.gov (United States)

Gross, R. S.

2017-12-01

The Global Geodetic Observing System (GGOS) of the International Association of Geodesy (IAG) provides the basis on which future advances in geosciences can be built. By considering the Earth system as a whole (including the geosphere, hydrosphere, cryosphere, atmosphere and biosphere), monitoring Earth system components and their interactions by geodetic techniques and studying them from the geodetic point of view, the geodetic community provides the global geosciences community with a powerful tool consisting mainly of high-quality services, standards and references, and theoretical and observational innovations. The mission of GGOS is: (a) to provide the observations needed to monitor, map and understand changes in the Earth's shape, rotation and mass distribution; (b) to provide the global frame of reference that is the fundamental backbone for measuring and consistently interpreting key global change processes and for many other scientific and societal applications; and (c) to benefit science and society by providing the foundation upon which advances in Earth and planetary system science and applications are built. The goals of GGOS are: (1) to be the primary source for all global geodetic information and expertise serving society and Earth system science; (2) to actively promote, sustain, improve, and evolve the integrated global geodetic infrastructure needed to meet Earth science and societal requirements; (3) to coordinate with the international geodetic services that are the main source of key parameters and products needed to realize a stable global frame of reference and to observe and study changes in the dynamic Earth system; (4) to communicate and advocate the benefits of GGOS to user communities, policy makers, funding organizations, and society. In order to accomplish its mission and goals, GGOS depends on the IAG Services, Commissions, and Inter-Commission Committees. The Services provide the infrastructure and products on which all contributions

The impacts of source structure on geodetic parameters demonstrated by the radio source 3C371

Science.gov (United States)

Xu, Ming H.; Heinkelmann, Robert; Anderson, James M.; Mora-Diaz, Julian; Karbon, Maria; Schuh, Harald; Wang, Guang L.

2017-07-01

Closure quantities measured by very-long-baseline interferometry (VLBI) observations are independent of instrumental and propagation instabilities and antenna gain factors, but are sensitive to source structure. A new method is proposed to calculate a structure index based on the median values of closure quantities rather than the brightness distribution of a source. The results are comparable to structure indices based on imaging observations at other epochs and demonstrate the flexibility of deriving structure indices from exactly the same observations as used for geodetic analysis and without imaging analysis. A three-component model for the structure of source 3C371 is developed by model-fitting closure phases. It provides a real case of tracing how the structure effect identified by closure phases in the same observations as the delay observables affects the geodetic analysis, and investigating which geodetic parameters are corrupted to what extent by the structure effect. Using the resulting structure correction based on the three-component model of source 3C371, two solutions, with and without correcting the structure effect, are made. With corrections, the overall rms of this source is reduced by 1 ps, and the impacts of the structure effect introduced by this single source are up to 1.4 mm on station positions and up to 4.4 microarcseconds on Earth orientation parameters. This study is considered as a starting point for handling the source structure effect on geodetic VLBI from geodetic sessions themselves.

Dynamic rupture modeling of the M7.2 2010 El Mayor-Cucapah earthquake: Comparison with a geodetic model

Science.gov (United States)

Kyriakopoulos, Christos; Oglesby, David D.; Funning, Gareth J.; Ryan, Kenneth

2017-01-01

The 2010 Mw 7.2 El Mayor-Cucapah earthquake is the largest event recorded in the broader Southern California-Baja California region in the last 18 years. Here we try to analyze primary features of this type of event by using dynamic rupture simulations based on a multifault interface and later compare our results with space geodetic models. Our results show that starting from homogeneous prestress conditions, slip heterogeneity can be achieved as a result of variable dip angle along strike and the modulation imposed by step over segments. We also considered effects from a topographic free surface and find that although this does not produce significant first-order effects for this earthquake, even a low topographic dome such as the Cucapah range can affect the rupture front pattern and fault slip rate. Finally, we inverted available interferometric synthetic aperture radar data, using the same geometry as the dynamic rupture model, and retrieved the space geodetic slip distribution that serves to constrain the dynamic rupture models. The one to one comparison of the final fault slip pattern generated with dynamic rupture models and the space geodetic inversion show good agreement. Our results lead us to the following conclusion: in a possible multifault rupture scenario, and if we have first-order geometry constraints, dynamic rupture models can be very efficient in predicting large-scale slip heterogeneities that are important for the correct assessment of seismic hazard and the magnitude of future events. Our work contributes to understanding the complex nature of multifault systems.

Explicitly computing geodetic coordinates from Cartesian coordinates

Science.gov (United States)

Zeng, Huaien

2013-04-01

This paper presents a new form of quartic equation based on Lagrange's extremum law and a Groebner basis under the constraint that the geodetic height is the shortest distance between a given point and the reference ellipsoid. A very explicit and concise formulae of the quartic equation by Ferrari's line is found, which avoids the need of a good starting guess for iterative methods. A new explicit algorithm is then proposed to compute geodetic coordinates from Cartesian coordinates. The convergence region of the algorithm is investigated and the corresponding correct solution is given. Lastly, the algorithm is validated with numerical experiments.

Research in Application of Geodetic GPS Receivers in Time Synchronization

Science.gov (United States)

Zhang, Q.; Zhang, P.; Sun, Z.; Wang, F.; Wang, X.

2018-04-01

2 common-view satellites for each tracking period when the elevation angle is 30°. Data processing used precise GPS satellite ephemeris, double-frequency P-code combination observations without ionosphere effects and the correction of the Black troposphere Delay Model. the weighted average of all common-viewed GPS satellites in the same tracking period is taken by weighting the root-mean-square error of each satellite, finally a time comparison data between two stations is obtained, and then the time synchronization result between the two stations (PTB and USNO) is obtained. It can be seen from the analysis of time synchronization result that the root mean square error of REFSV (the difference between the local frequency standard at the mid-point of the actual tracking length and the tracked satellite time in unit of 0.1 ns) shows a linear change within one day, However the jump occurs when jumping over the day which is mainly caused by satellites position being changed due to the interpolation of two-day precise satellite ephemeris across the day. the overall trend of time synchronization result is declining and tends to be stable within a week-long time. We compared the time synchronization results (without considering the hardware delay correction) with those published by the International Bureau of Weights and Measures (BIPM), and the comparing result from a week earlier shows that the trend is same but there is a systematic bias which was mainly caused by hardware delays of geodetic GPS receiver. Regardless of the hardware delay, the comparing result is about between 102 ns and 106 ns. the vast majority of the difference within 2 ns but the difference of individual moment does not exceed 4ns when taking into account the systemic bias which mainly caused by hardware delay. Therefore, it is feasible to use the geodetic GPS receiver to achieve the time synchronization result in nanosecond order between two stations which separated by thousands kilometers, and

RESEARCH IN APPLICATION OF GEODETIC GPS RECEIVERS IN TIME SYNCHRONIZATION

Directory of Open Access Journals (Sweden)

Q. Zhang

2018-04-01

there will be at least 2 common-view satellites for each tracking period when the elevation angle is 30°. Data processing used precise GPS satellite ephemeris, double-frequency P-code combination observations without ionosphere effects and the correction of the Black troposphere Delay Model. the weighted average of all common-viewed GPS satellites in the same tracking period is taken by weighting the root-mean-square error of each satellite, finally a time comparison data between two stations is obtained, and then the time synchronization result between the two stations (PTB and USNO is obtained. It can be seen from the analysis of time synchronization result that the root mean square error of REFSV (the difference between the local frequency standard at the mid-point of the actual tracking length and the tracked satellite time in unit of 0.1 ns shows a linear change within one day, However the jump occurs when jumping over the day which is mainly caused by satellites position being changed due to the interpolation of two-day precise satellite ephemeris across the day. the overall trend of time synchronization result is declining and tends to be stable within a week-long time. We compared the time synchronization results (without considering the hardware delay correction with those published by the International Bureau of Weights and Measures (BIPM, and the comparing result from a week earlier shows that the trend is same but there is a systematic bias which was mainly caused by hardware delays of geodetic GPS receiver. Regardless of the hardware delay, the comparing result is about between 102 ns and 106 ns. the vast majority of the difference within 2 ns but the difference of individual moment does not exceed 4ns when taking into account the systemic bias which mainly caused by hardware delay. Therefore, it is feasible to use the geodetic GPS receiver to achieve the time synchronization result in nanosecond order between two stations which separated by

NASA Space Geodesy Program: GSFC data analysis, 1993. VLBI geodetic results 1979 - 1992

Science.gov (United States)

Ma, Chopo; Ryan, James W.; Caprette, Douglas S.

1994-01-01

The Goddard VLBI group reports the results of analyzing Mark 3 data sets acquired from 110 fixed and mobile observing sites through the end of 1992 and available to the Space Geodesy Program. Two large solutions were used to obtain site positions, site velocities, baseline evolution for 474 baselines, earth rotation parameters, nutation offsets, and radio source positions. Site velocities are presented in both geocentric Cartesian and topocentric coordinates. Baseline evolution is plotted for the 89 baselines that were observed in 1992 and positions at 1988.0 are presented for all fixed stations and mobile sites. Positions are also presented for quasar radio sources used in the solutions.

Development of web tools to disseminate space geodesy data-related products

Science.gov (United States)

Soudarin, Laurent; Ferrage, Pascale; Mezerette, Adrien

2015-04-01

In order to promote the products of the DORIS system, the French Space Agency CNES has developed and implemented on the web site of the International DORIS Service (IDS) a set of plot tools to interactively build and display time series of site positions, orbit residuals and terrestrial parameters (scale, geocenter). An interactive global map is also available to select sites, and to get access to their information. Besides the products provided by the CNES Orbitography Team and the IDS components, these tools allow comparing time evolutions of coordinates for collocated DORIS and GNSS stations, thanks to the collaboration with the Terrestrial Frame Combination Center of the International GNSS Service (IGS). A database was created to improve robustness and efficiency of the tools, with the objective to propose a complete web service to foster data exchange with the other geodetic services of the International Association of Geodesy (IAG). The possibility to visualize and compare position time series of the four main space geodetic techniques DORIS, GNSS, SLR and VLBI is already under way at the French level. A dedicated version of these web tools has been developed for the French Space Geodesy Research Group (GRGS). It will give access to position time series provided by the GRGS Analysis Centers involved in DORIS, GNSS, SLR and VLBI data processing for the realization of the International Terrestrial Reference Frame. In this presentation, we will describe the functionalities of these tools, and we will address some aspects of the time series (content, format).

NASA's Next Generation Space Geodesy Program

Science.gov (United States)

Merkowitz, S. M.; Desai, S. D.; Gross, R. S.; Hillard, L. M.; Lemoine, F. G.; Long, J. L.; Ma, C.; McGarry, J. F.; Murphy, D.; Noll, C. E.;

GEOdetic Data assimilation and EStimation of references for climate change InvEstigation. An overall presentation of the French GEODESIE project

Science.gov (United States)

Nahmani, S.; Coulot, D.; Biancale, R.; Bizouard, C.; Bonnefond, P.; Bouquillon, S.; Collilieux, X.; Deleflie, F.; Garayt, B.; Lambert, S. B.; Laurent-Varin, S.; Marty, J. C.; Mercier, F.; Metivier, L.; Meyssignac, B.; Pollet, A.; Rebischung, P.; Reinquin, F.; Richard, J. Y.; Tertre, F.; Woppelmann, G.

2017-12-01

Many major indicators of climate change are monitored with space observations. This monitoring is highly dependent on references that only geodesy can provide. The current accuracy of these references does not permit to fully support the challenges that the constantly evolving Earth system gives rise to, and can consequently limit the accuracy of these indicators. Thus, in the framework of the GGOS, stringent requirements are fixed to the International Terrestrial Reference Frame (ITRF) for the next decade: an accuracy at the level of 1 mm and a stability at the level of 0.1 mm/yr. This means an improvement of the current quality of ITRF by a factor of 5-10. Improving the quality of the geodetic references is an issue which requires a thorough reassessment of the methodologies involved. The most relevant and promising method to improve this quality is the direct combination of the space-geodetic measurements used to compute the official references of the IERS. The GEODESIE project aims at (i) determining highly-accurate global and consistent references and (ii) providing the geophysical and climate research communities with these references, for a better estimation of geocentric sea level rise, ice mass balance and on-going climate changes. Time series of sea levels computed from altimetric data and tide gauge records with these references will also be provided. The geodetic references will be essential bases for Earth's observation and monitoring to support the challenges of the century. The geocentric time series of sea levels will permit to better apprehend (i) the drivers of the global mean sea level rise and of regional variations of sea level and (ii) the contribution of the global climate change induced by anthropogenic greenhouse gases emissions to these drivers. All the results and computation and quality assessment reports will be available at geodesie_anr.ign.fr.This project, supported by the French Agence Nationale de la Recherche (ANR) for the period

Relativistic positioning in Schwarzschild space-time

International Nuclear Information System (INIS)

Puchades, Neus; Sáez, Diego

2015-01-01

In the Schwarzschild space-time created by an idealized static spherically symmetric Earth, two approaches -based on relativistic positioning- may be used to estimate the user position from the proper times broadcast by four satellites. In the first approach, satellites move in the Schwarzschild space-time and the photons emitted by the satellites follow null geodesics of the Minkowski space-time asymptotic to the Schwarzschild geometry. This assumption leads to positioning errors since the photon world lines are not geodesics of any Minkowski geometry. In the second approach -the most coherent one- satellites and photons move in the Schwarzschild space-time. This approach is a first order one in the dimensionless parameter GM/R (with the speed of light c=1). The two approaches give different inertial coordinates for a given user. The differences are estimated and appropriately represented for users located inside a great region surrounding Earth. The resulting values (errors) are small enough to justify the use of the first approach, which is the simplest and the most manageable one. The satellite evolution mimics that of the GALILEO global navigation satellite system. (paper)

Angular Positioning Sensor for Space Mechanisms

Science.gov (United States)

Steiner, Nicolas; Chapuis, Dominique

2013-09-01

Angular position sensors are used on various rotating mechanisms such as solar array drive mechanisms, antenna pointing mechanisms, scientific instruments, motors or actuators.Now a days, potentiometers and encoders are mainly used for angular measurement purposes. Both of them have their own pros and cons.As alternative, Ruag Space Switzerland Nyon (RSSN) is developing and qualifying two innovative technologies of angular position sensors which offer easy implementation, medium to very high lifetime and high flexibility with regards to the output signal shape/type.The Brushed angular position sensor uses space qualified processes which are already flying on RSSN's sliprings for many years. A large variety of output signal shape can be implemented to fulfill customer requirements (digital, analog, customized, etc.).The contactless angular position sensor consists in a new radiation hard Application Specific Integrated Circuit (ASIC) based on the Hall effect and providing the angular position without complex processing algorithm.

COORDINATE TRANSFORMATION USING FEATHERSTONE AND VANÍČEK PROPOSED APPROACH - A CASE STUDY OF GHANA GEODETIC REFERENCE NETWORK

Directory of Open Access Journals (Sweden)

Yao Yevenyo Ziggah

2017-03-01

Full Text Available Most developing countries like Ghana are yet to adopt the geocentric datum for its surveying and mapping purposes. It is well known and documented that non-geocentric datums based on its establishment have more distortions in height compared with satellite datums. Most authors have argued that combining such height with horizontal positions (latitude and longitude in the transformation process could introduce unwanted distortions to the network. This is because the local geodetic height in most cases is assumed to be determined to a lower accuracy compared with the horizontal positions. In the light of this, a transformation model was proposed by Featherstone and Vaníček (1999 which avoids the use of height in both global and local datums in coordinate transformation. It was confirmed that adopting such a method reduces the effect of distortions caused by geodetic height on the transformation parameters estimated. Therefore, this paper applied Featherstone and Vaníček (FV model for the first time to a set of common points coordinates in Ghana geodetic reference network. The FV model was used to transform coordinates from global datum (WGS84 to local datum (Accra datum. The results obtained based on the Root Mean Square Error (RMSE and Mean Absolute Error (MAE in both Eastings and Northings were satisfactory. Thus, a RMSE value of 0.66 m and 0.96 m were obtained for the Eastings and Northings while 0.76 m and 0.73 m were the MAE values achieved. Also, the FV model attained a transformation accuracy of 0.49 m. Hence, this study will serve as a preliminary investigation in avoiding the use of height in coordinate transformation within Ghana’s geodetic reference network.

Evaluation on the performance of single and dual frequency low cost GPS module observation using geodetic antenna

Directory of Open Access Journals (Sweden)

Dedi Atunggal

2018-06-01

Full Text Available GPS modules have been used for various applications in recent years. Its early development came in parallel with the advancement of Unmanned Aerial Vehicle (UAV technology. Nowadays, it is also used in in geographic information system (GIS data acquisition/census, mapping surveys, structure stability monitoring systems and many other applications. GPS modules generally have several positioning features, including standard positioning service (SPS, static positioning, precise point positioning (PPP, post processing kinematic (PPK and real time kinematic (RTK GPS. GPS modules in general are only equipped with a microstrip-type antenna or better known as patch antenna. Results from related research show that GPS module with this type of antenna has sub meter accuracy when used for PPK or RTK GPS method. The use of geodetic antennas is very potential to increase GPS position accuracy by up to centimeter level. This paper discusses the evaluation of GPS module measurements with geodetic type antennas for precise positioning using RTK GPS. This paper is focused on the resolution of GPS cycle ambiguity that is often expressed by the term fixing ratio and the accuracy of measurement results obtained. To provide a comprehensive description of the performance of GPS module, in this research two types of GPS module were used; single and dual frequency. Both types of GPS modules were used to conduct simultaneous observation on an open and obstructed observation location.

Multi-scale model of the ionosphere from the combination of modern space-geodetic satellite techniques - project status and first results

Science.gov (United States)

Schmidt, M.; Hugentobler, U.; Jakowski, N.; Dettmering, D.; Liang, W.; Limberger, M.; Wilken, V.; Gerzen, T.; Hoque, M.; Berdermann, J.

2012-04-01

Near real-time high resolution and high precision ionosphere models are needed for a large number of applications, e.g. in navigation, positioning, telecommunications or astronautics. Today these ionosphere models are mostly empirical, i.e., based purely on mathematical approaches. In the DFG project 'Multi-scale model of the ionosphere from the combination of modern space-geodetic satellite techniques (MuSIK)' the complex phenomena within the ionosphere are described vertically by combining the Chapman electron density profile with a plasmasphere layer. In order to consider the horizontal and temporal behaviour the fundamental target parameters of this physics-motivated approach are modelled by series expansions in terms of tensor products of localizing B-spline functions depending on longitude, latitude and time. For testing the procedure the model will be applied to an appropriate region in South America, which covers relevant ionospheric processes and phenomena such as the Equatorial Anomaly. The project connects the expertise of the three project partners, namely Deutsches Geodätisches Forschungsinstitut (DGFI) Munich, the Institute of Astronomical and Physical Geodesy (IAPG) of the Technical University Munich (TUM) and the German Aerospace Center (DLR), Neustrelitz. In this presentation we focus on the current status of the project. In the first year of the project we studied the behaviour of the ionosphere in the test region, we setup appropriate test periods covering high and low solar activity as well as winter and summer and started the data collection, analysis, pre-processing and archiving. We developed partly the mathematical-physical modelling approach and performed first computations based on simulated input data. Here we present information on the data coverage for the area and the time periods of our investigations and we outline challenges of the multi-dimensional mathematical-physical modelling approach. We show first results, discuss problems

How well can online GPS PPP post-processing services be used to establish geodetic survey control networks?

Science.gov (United States)

Ebner, R.; Featherstone, W. E.

2008-09-01

Establishing geodetic control networks for subsequent surveys can be a costly business, even when using GPS. Multiple stations should be occupied simultaneously and post-processed with scientific software. However, the free availability of online GPS precise point positioning (PPP) post-processing services offer the opportunity to establish a whole geodetic control network with just one dual-frequency receiver and one field crew. To test this idea, we compared coordinates from a moderate-sized (~550 km by ~440 km) geodetic network of 46 points over part of south-western Western Australia, which were processed both with the Bernese v5 scientific software and with the CSRS (Canadian Spatial Reference System) PPP free online service. After rejection of five stations where the antenna type was not recognised by CSRS, the PPP solutions agreed on average with the Bernese solutions to 3.3 mm in east, 4.8 mm in north and 11.8 mm in height. The average standard deviations of the Bernese solutions were 1.0 mm in east, 1.2 mm in north and 6.2 mm in height, whereas for CSRS they were 3.9 mm in east, 1.9 mm in north and 7.8 mm in height, reflecting the inherently lower precision of PPP. However, at the 99% confidence level, only one CSRS solution was statistically different to the Bernese solution in the north component, due to a data interruption at that site. Nevertheless, PPP can still be used to establish geodetic survey control, albeit with a slightly lower quality because of the larger standard deviations. This approach may be of particular benefit in developing countries or remote regions, where geodetic infrastructure is sparse and would not normally be established without this approach.

Global tectonics and space geodesy

Science.gov (United States)

Gordon, Richard G.; Stein, Seth

1992-01-01

Much of the success of plate tectonics can be attributed to the near rigidity of tectonic plates and the availability of data that describe the rates and directions of motion across narrow plate boundaries of about 1 to 60 kilometers. Nonetheless, many plate boundaries in both continental and oceanic lithosphere are not narrow but are hundreds to thousands of kilometers wide. Wide plate boundary zones cover approximately 15 percent of earth's surface area. Space geodesy, which includes very long baseline radio interferometry, satellite laser ranging, and the global positioning system, provides the accurate long-distance measurements needed to estimate the present motion across and within wide plate boundary zones. Space geodetic data show that plate velocities averaged over years are remarkably similar to velocities avaraged over millions of years.

Geodetic precession or dragging of inertial frames?

International Nuclear Information System (INIS)

Ashby, N.; Shahid-Saless, B.

1990-01-01

In metric theories of gravity the principle of general covariance allows one to describe phenomena by means of any convenient choice of coordinate system. In this paper it is shown that in an appropriately chosen coordinate system, geodetic precession of a gyroscope orbiting a spherically symmetric, spinning mass can be recast as a Lense-Thirring frame-dragging effect without invoking spatial curvature. The origin of this reference frame moves around the source but the frame axes point in fixed directions. The drag can be interpreted to arise from the orbital angular momentum of the source around the origin of the reference frame. In this reference frame the effects of geodetic precession and Lense-Thirring drag due to intrinsic angular momentum of the source have the same origin, namely, gravitomagnetism

Comparison of direct and geodetic mass balances on a multi-annual time scale

Directory of Open Access Journals (Sweden)

A. Fischer

2011-02-01

Full Text Available The geodetic mass balances of six Austrian glaciers over 19 periods between 1953 and 2006 are compared to the direct mass balances over the same periods. For two glaciers, Hintereisferner and Kesselwandferner, case studies showing possible reasons for discrepancies between the geodetic and the direct mass balance are presented. The mean annual geodetic mass balance for all periods is −0.5 m w.e. a⁻¹, the mean annual direct mass balance −0.4 m w.e. a⁻¹. The mean cumulative difference is −0.6 m w.e., the minimum −7.3 m w.e., and the maximum 5.6 m w.e. The accuracy of geodetic mass balance may depend on the accuracy of the DEMs, which ranges from 2 m w.e. for photogrammetric data to 0.02 m w.e. for airborne laser scanning (LiDAR data. Basal melt, seasonal snow cover, and density changes of the surface layer also contribute up to 0.7 m w.e. to the difference between the two methods over the investigated period of 10 yr. On Hintereisferner, the fraction of area covered by snow or firn has been changing within 1953–2006. The accumulation area is not identical with the firn area, and both are not coincident with areas of volume gain. Longer periods between the acquisition of the DEMs do not necessarily result in a higher accuracy of the geodetic mass balance. Trends in the difference between the direct and the geodetic data vary from glacier to glacier and can differ systematically for specific glaciers under specific types of climate forcing. Ultimately, geodetic and direct mass balance data are complementary, and great care must be taken when attempting to combine them.

Operational production of Geodetic Excitation Functions from EOP estimated values at ASI-CGS

Science.gov (United States)

Sciarretta, C.; Luceri, V.; Bianco, G.

2009-04-01

ASI-CGS is routinely providing geodetic excitation functions from its own estimated EOP values (at present SLR and VLBI; the current use of GPS EOP's is also planned as soon as this product will be fully operational) on the ASI geodetic web site (http://geodaf.mt.asi.it). This product has been generated and monitored (for ASI internal use only) in a long pre-operational phase (more than two years), including validation and testing. The daily geodetic excitation functions are now weekly updated along with the operational ASI SLR and VLBI EOP solutions and compared, whenever possible, with the atmospheric excitation functions available at the IERS SBAAM, under the IB and not-IB assumption, including the "wind" term. The work will present the available estimated geodetic function time series and its comparison with the relevant atmospheric excitation functions, deriving quantitative indicators on the quality of the estimates. The similarities as well as the discrepancies among the atmospheric and geodetic series will be analysed and commented, evaluating in particular the degree of correlation among the two estimated time series and the likelihood of a linear dependence hypothesis.

Determination of Geometric Parameters of Space Steel Constructions

Directory of Open Access Journals (Sweden)

Jitka Suchá

2005-06-01

Full Text Available The paper contains conclusions of the PhD thesis „Accuracy of determination of geometric parameters of space steel construction using geodetic methods“. Generally it is a difficult task with high requirements for the accuracy and reliability of results, i.e. space coordinates of assessed points on a steel construction. A solution of this task is complicated by the effects of atmospheric influences to begin with the temperature, which strongly affects steel constructions. It is desirable to eliminate the influence of the temperature for the evaluation of the geometric parameters. A choice of an efficient geodetic method, which fulfils demanding requirements, is often affected with a constrained place in an immediate neighbourhood of the measured construction. These conditions disable the choice of efficient points configuration of a geodetic micro network, e.g. the for forward intersection. In addition, points of a construction are often hardly accessible and therefore marking is difficult. The space polar method appears efficient owing to the mentioned reasons and its advantages were increased with the implementation of self-adhesive reflex targets for the distance measurement which enable the ermanent marking of measured points already in the course of placing the construction.

Enhanced three-dimensional stochastic adjustment for combined volcano geodetic networks

Science.gov (United States)

Del Potro, R.; Muller, C.

2009-12-01

Volcano geodesy is unquestionably a necessary technique in studies of physical volcanology and for eruption early warning systems. However, as every volcano geodesist knows, obtaining measurements of the required resolution using traditional campaigns and techniques is time consuming and requires a large manpower. Moreover, most volcano geodetic networks worldwide use a combination of data from traditional techniques; levelling, electronic distance measurements (EDM), triangulation and Global Navigation Satellite Systems (GNSS) but, in most cases, these data are surveyed, analysed and adjusted independently. This then leaves it to the authors’ criteria to decide which technique renders the most realistic results in each case. Herein we present a way of solving the problem of inter-methodology data integration in a cost-effective manner following a methodology were all the geodetic data of a redundant, combined network (e.g. surveyed by GNSS, levelling, distance, angular data, INSAR, extensometers, etc.) is adjusted stochastically within a single three-dimensional referential frame. The adjustment methodology is based on the least mean square method and links the data with its geometrical component providing combined, precise, three-dimensional, displacement vectors, relative to external reference points as well as stochastically-quantified, benchmark-specific, uncertainty ellipsoids. Three steps in the adjustment allow identifying, and hence dismissing, flagrant measurement errors (antenna height, atmospheric effects, etc.), checking the consistency of external reference points and a final adjustment of the data. Moreover, since the statistical indicators can be obtained from expected uncertainties in the measurements of the different geodetic techniques used (i.e. independent of the measured data), it is possible to run a priori simulations of a geodetic network in order to constrain its resolution, and reduce logistics, before the network is even built. In this

Geodetic alignment of laser power installations

International Nuclear Information System (INIS)

Shtorm, V.V.; Gostev, A.M.; Drobikov, A.V.

1989-01-01

Main problems occuring in applied geodesy under initial alignment of laser power installation optical channel are considered. Attention is paid to alignment of lens beamguide telescopic pairs and alignment quality control. Methods and means of geodetic measurements under alignment are indicated. Conclusions are made about the degree of working through certain aspects of the problem

Geodetic Control Points - Multi-State Control Point Database

Data.gov (United States)

NSGIC State | GIS Inventory — The Multi-State Control Point Database (MCPD) is a database of geodetic and mapping control covering Idaho and Montana. The control were submitted by registered land...

GBIS (Geodetic Bayesian Inversion Software): Rapid Inversion of InSAR and GNSS Data to Estimate Surface Deformation Source Parameters and Uncertainties

Science.gov (United States)

Bagnardi, M.; Hooper, A. J.

2017-12-01

Inversions of geodetic observational data, such as Interferometric Synthetic Aperture Radar (InSAR) and Global Navigation Satellite System (GNSS) measurements, are often performed to obtain information about the source of surface displacements. Inverse problem theory has been applied to study magmatic processes, the earthquake cycle, and other phenomena that cause deformation of the Earth's interior and of its surface. Together with increasing improvements in data resolution, both spatial and temporal, new satellite missions (e.g., European Commission's Sentinel-1 satellites) are providing the unprecedented opportunity to access space-geodetic data within hours from their acquisition. To truly take advantage of these opportunities we must become able to interpret geodetic data in a rapid and robust manner. Here we present the open-source Geodetic Bayesian Inversion Software (GBIS; available for download at http://comet.nerc.ac.uk/gbis). GBIS is written in Matlab and offers a series of user-friendly and interactive pre- and post-processing tools. For example, an interactive function has been developed to estimate the characteristics of noise in InSAR data by calculating the experimental semi-variogram. The inversion software uses a Markov-chain Monte Carlo algorithm, incorporating the Metropolis-Hastings algorithm with adaptive step size, to efficiently sample the posterior probability distribution of the different source parameters. The probabilistic Bayesian approach allows the user to retrieve estimates of the optimal (best-fitting) deformation source parameters together with the associated uncertainties produced by errors in the data (and by scaling, errors in the model). The current version of GBIS (V1.0) includes fast analytical forward models for magmatic sources of different geometry (e.g., point source, finite spherical source, prolate spheroid source, penny-shaped sill-like source, and dipping-dike with uniform opening) and for dipping faults with uniform

Stability of Global Geodetic Results

Science.gov (United States)

Herring, T.

The precision of global geodetic techniques has reached unprecedented levels. Sys- tems capable of millimeter level horizontal and several millimeter vertical precisions are now deployed. The Global Positioning System (GPS) has the most deployed continuously-operating receivers with several hundred providing data through the in- ternet for analysis. However, the satellite system used with GPS evolves with time as new generations of GPS satellites are launched. During the 1990's, the constellation evolved from Block I to Block II and IIA with the most recent generation being Block IIR. There are considerable differences in the size and antenna configurations in the different generations of satellites. The antenna configuration specifically could cause systematic changes in the terrestrial reference system. Results from the ITRF2000 combinations suggest that there are significant time variations in the scale of GPS system possibly due to phase center variations in GPS transmission antennas. These variations could result in height changes of up to 3 mm/yr. We will investigate the stability of the GPS system through combination of GPS results with results from VLBI and SLR. All components of the transformation between the systems, rotation, translation and scale will be investigated.

Results from the Geodetic Observatory TIGO due to the Mw 8.8 Earthquake

Science.gov (United States)

Hase, H.; Böer, A.; Sierk, B.; Ihde, J.; Weber, G.; Wilmes, H.; Falk, R.; Hessels, U.; Neumaier, P.; Söhne, W.; Wziontek, H.; Engelhard, G.; Sobarzo, S.; Cifuentes, O.; Guaitiao, C.; Cona, I.; Avendaño, M.; Herrera, C.; Mora, V.; Fernandez, A.; Oñate, E.; Zaror, P.; Pedreros, F.; Zapata, O.

2010-12-01

The Geodetic Observatory TIGO is unique in Latin America. With its sensors and instruments it defines a reference point in the time, space and gravity field domain. Its operation started in 2002, for which reason data series documented the preseismic situation very well. With the Mw 8.8 earthquake on February 27, 2010, the entire observatory was exposed to strong motions due to its closeness to the epicenter. Since then the postseismic behaviour of the subduction zone can be studied and compared with the preseismic situation. TIGO provided continuous GPS/GLONASS data with 1s samples which give an insight to the mechanism of the decoupling of the Nazca and the South-American plate. The displacement of more than 3m had a duration of 30s at the beginning of the 147s duration of the earthquake. The displacement could be confirmed afterwards with VLBI and SLR methods. TIGO used its absolute gravity meter in an unusual way with weekly measurements on the same monument. These data show an irregularity during the last 3 weeks before the earthquake. Finally the postseismic movement to the west triggered by the earthquake and registered by geodetic space techniques indicate that the western expansion of the South-American plate did not stop yet. The pre- and post-seismic displacement vectors differ by less than 180° which might be explained by a fractional strike slip in the mega thrust. The coincidence of the epicenter with one of the keystations for global reference frames showed deficiencies by the linear modelling of tectonical movements in terrestial reference frames. This problem calls for near-real time reference frames.

Convexity Of Inversion For Positive Operators On A Hilbert Space

International Nuclear Information System (INIS)

Sangadji

2001-01-01

This paper discusses and proves three theorems for positive invertible operators on a Hilbert space. The first theorem gives a comparison of the generalized arithmetic mean, generalized geometric mean, and generalized harmonic mean for positive invertible operators on a Hilbert space. For the second and third theorems each gives three inequalities for positive invertible operators on a Hilbert space that are mutually equivalent

The current state of the creation and modernization of national geodetic and cartographic resources in Poland

Directory of Open Access Journals (Sweden)

Doskocz Adam

2016-01-01

Full Text Available All official data are currently integrated and harmonized in a spatial reference system. This paper outlines a national geodetic and cartographic resources in Poland. The national geodetic and cartographic resources are an important part of the spatial information infrastructure in the European Community. They also provide reference data for other resources of Spatial Data Infrastructure (SDI, including: main and detailed geodetic control networks, base maps, land and buildings registries, geodetic registries of utilities and topographic maps. This paper presents methods of producing digital map data and technical standards for field surveys, and in addition paper also presents some aspects of building Global and Regional SDI.

Geodetic analysis of disputed accurate qibla direction

Science.gov (United States)

Saksono, Tono; Fulazzaky, Mohamad Ali; Sari, Zamah

2018-04-01

Muslims perform the prayers facing towards the correct qibla direction would be the only one of the practical issues in linking theoretical studies with practice. The concept of facing towards the Kaaba in Mecca during the prayers has long been the source of controversy among the muslim communities to not only in poor and developing countries but also in developed countries. The aims of this study were to analyse the geodetic azimuths of qibla calculated using three different models of the Earth. The use of ellipsoidal model of the Earth could be the best method for determining the accurate direction of Kaaba from anywhere on the Earth's surface. A muslim cannot direct himself towards the qibla correctly if he cannot see the Kaaba due to setting out process and certain motions during the prayer this can significantly shift the qibla direction from the actual position of the Kaaba. The requirement of muslim prayed facing towards the Kaaba is more as spiritual prerequisite rather than physical evidence.

Geodetic Slip Solution for the Mw=7.4 Champerico (Guatemala) Earthquake of 07 November 2012

Science.gov (United States)

Ellis, A. P.; DeMets, C.; Briole, P.; Molina, E.; Flores, O.; Rivera, J.; Lasserre, C.; Lyon-Caen, H.; Lord, N. E.

2014-12-01

As the first large subduction thrust earthquake off the coast of western Guatemala in the past several decades, the 07 November 2012 Mw=7.4 earthquake offers the first opportunity for a geodetic study of coseismic and postseismic behavior for a segment of the Middle America trench where frictional coupling makes a transition from weak coupling off the coast of El Salvador to strong coupling in southern Mexico. We use measurements at 19 continuous GPS sites in Guatemala, El Salvador, and Mexico to estimate the coseismic slip and post-seismic deformation of the November 2012 Champerico (Guatemala) earthquake. Coseismic offsets range from ~47 mm near the epicenter to El Salvador. An inversion of the geodetic data indicate that that up to ~2 m of coseismic slip occurred on a ~30 km by 30 km rupture area between ~10 and 30 km depth, encouragingly close to the global CMT epicenter. The geodetic moment of 13 x 1019 N·m and corresponding magnitude of 7.4 both agree well with independent seismological estimates. An inversion for the postseismic fault afterslip shows that the transient postseismic motions recorded at 11 GPS sites are well fit with a logarithmically decaying function. More than 70 per cent of the postseismic slip occurred at the same depth or directly downdip from the main shock epicenter. At the upper limit, afterslip that occurred within 6 months of the earthquake released energy equivalent to only ~20 per cent of the coseismic moment. The seismologically derived slip solution from Ye et al. (2012), which features more highly concentrated slip than our own, fits our GPS offsets reasonably well provided that we translate their slip centroid ~51 km to the west to a position close to our own slip centroid. The geodetic and seismologic slip solutions thus suggest bounds of 2-5 m for the peak slip along a region of the interface no larger than 30 x 30 km and possibly much smaller.

Error Propagation in Geodetic Networks Studied by FEMLAB

DEFF Research Database (Denmark)

Borre, Kai

2009-01-01

Geodetic networks can be described by discrete models. The observations may be height differences, distances, and directions. Geodesists always make more observations than necessary and estimate the solution by using the principle of least squares. Contemporary networks often contain several thou...

An Overview of Geodetic Volcano Research in the Canary Islands

Science.gov (United States)

Fernández, José; González, Pablo J.; Camacho, Antonio G.; Prieto, Juan F.; Brú, Guadalupe

2015-11-01

The Canary Islands are mostly characterized by diffuse and scattered volcanism affecting a large area, with only one active stratovolcano, the Teide-Pico Viejo complex (Tenerife). More than 2 million people live and work in the 7,447 km2 of the archipelago, resulting in an average population density three times greater than the rest of Spain. This fact, together with the growth of exposure during the past 40 years, increases volcanic risk with respect previous eruptions, as witnessed during the recent 2011-2012 El Hierro submarine eruption. Therefore, in addition to purely scientific reasons there are economic and population-security reasons for developing and maintaining an efficient volcano monitoring system. In this scenario geodetic monitoring represents an important part of the monitoring system. We describe volcano geodetic monitoring research carried out in the Canary Islands and the results obtained. We consider for each epoch the two main existing constraints: the level of volcanic activity in the archipelago, and the limitations of the techniques available at the time. Theoretical and observational aspects are considered, as well as the implications for operational volcano surveillance. Current challenges of and future perspectives in geodetic volcano monitoring in the Canaries are also presented.

GeoSEA: Geodetic Earthquake Observatory on the Seafloor

Science.gov (United States)

Kopp, Heidrun; Lange, Dietrich; Flueh, Ernst R.; Petersen, Florian; Behrmann, Jan-Hinrich; Devey, Colin

2014-05-01

Space geodetic observations of crustal deformation have contributed greatly to our understanding of plate tectonic processes in general, and plate subduction in particular. Measurements of interseismic strain have documented the active accumulation of strain, and subsequent strain release during earthquakes. However, techniques such as GPS cannot be applied below the water surface because the electromagnetic energy is strongly attenuated in the water column. Evidence suggests that much of the elastic strain build up and release (and particularly that responsible for both tsunami generation and giant earthquakes) occurs offshore. To quantify strain accumulation and assess the resultant hazard potential we urgently need systems to resolve seafloor crustal deformation. Here we report on first results of sea trials of a newly implemented seafloor geodesy array. The GeoSEA (Geodetic Earthquake Observatory on the Seafloor) array consists of a seafloor transponder network comprising 35 units and a wave glider acting as a surface unit (GeoSURF) to ensure satellite correspondence, data transfer and monitor system health. Seafloor displacement occurs in the horizontal (x,y) and vertical direction (z). The vertical displacement is measured by monitoring pressure variations at the seafloor. Horizontal seafloor displacement can be measured either using an acoustic/GPS combination to provide absolute positioning (requiring a suitably equipped vessel to perform repeated cruises to provide the GPS fixes) or by long-term acoustic telemetry between different beacons fixed on the seafloor to determine relative distances by using the travel time observations to each other, which is the technique tested during our short sea trials. For horizontal direct path measurements, the system utilizes acoustic ranging techniques with a ranging precision better than 15 mm and long term stability over 2 km distances. Vertical motion is obtained from pressure gauges. Integrated inclinometers

Propagation of uncertainty by Monte Carlo simulations in case of basic geodetic computations

Directory of Open Access Journals (Sweden)

Wyszkowska Patrycja

2017-12-01

Full Text Available The determination of the accuracy of functions of measured or adjusted values may be a problem in geodetic computations. The general law of covariance propagation or in case of the uncorrelated observations the propagation of variance (or the Gaussian formula are commonly used for that purpose. That approach is theoretically justified for the linear functions. In case of the non-linear functions, the first-order Taylor series expansion is usually used but that solution is affected by the expansion error. The aim of the study is to determine the applicability of the general variance propagation law in case of the non-linear functions used in basic geodetic computations. The paper presents errors which are a result of negligence of the higher-order expressions and it determines the range of such simplification. The basis of that analysis is the comparison of the results obtained by the law of propagation of variance and the probabilistic approach, namely Monte Carlo simulations. Both methods are used to determine the accuracy of the following geodetic computations: the Cartesian coordinates of unknown point in the three-point resection problem, azimuths and distances of the Cartesian coordinates, height differences in the trigonometric and the geometric levelling. These simulations and the analysis of the results confirm the possibility of applying the general law of variance propagation in basic geodetic computations even if the functions are non-linear. The only condition is the accuracy of observations, which cannot be too low. Generally, this is not a problem with using present geodetic instruments.

Propagation of uncertainty by Monte Carlo simulations in case of basic geodetic computations

Science.gov (United States)

Wyszkowska, Patrycja

2017-12-01

The determination of the accuracy of functions of measured or adjusted values may be a problem in geodetic computations. The general law of covariance propagation or in case of the uncorrelated observations the propagation of variance (or the Gaussian formula) are commonly used for that purpose. That approach is theoretically justified for the linear functions. In case of the non-linear functions, the first-order Taylor series expansion is usually used but that solution is affected by the expansion error. The aim of the study is to determine the applicability of the general variance propagation law in case of the non-linear functions used in basic geodetic computations. The paper presents errors which are a result of negligence of the higher-order expressions and it determines the range of such simplification. The basis of that analysis is the comparison of the results obtained by the law of propagation of variance and the probabilistic approach, namely Monte Carlo simulations. Both methods are used to determine the accuracy of the following geodetic computations: the Cartesian coordinates of unknown point in the three-point resection problem, azimuths and distances of the Cartesian coordinates, height differences in the trigonometric and the geometric levelling. These simulations and the analysis of the results confirm the possibility of applying the general law of variance propagation in basic geodetic computations even if the functions are non-linear. The only condition is the accuracy of observations, which cannot be too low. Generally, this is not a problem with using present geodetic instruments.

Geodetic Control Points, Benchmarks; Vertical elevation bench marks for monumented geodetic survey control points for which mean sea level elevations have been determined., Published in 1995, 1:24000 (1in=2000ft) scale, Rhode Island and Providence Plantations.

Data.gov (United States)

NSGIC State | GIS Inventory — Geodetic Control Points dataset current as of 1995. Benchmarks; Vertical elevation bench marks for monumented geodetic survey control points for which mean sea level...

Geodetic Imaging: Expanding the Boundaries of Geodesy in the 21st Century

Science.gov (United States)

Fernandez Diaz, J. C.; Carter, W. E.; Shrestha, R. L.; Glennie, C. L.

2013-12-01

High resolution (sub-meter) geodetic images covering tens to thousands of square kilometers have extended the boundaries of geodesy into related areas of the earth sciences, such as geomorphology and geodynamics, during the past decade, to archaeological exploration and site mapping during the past few years, and are now poised to transform studies of flora and fauna in the more remote regions of the world. Geodetic images produced from airborne laser scanning (ALS), a.k.a. airborne light detection and ranging (LiDAR) have proven transformative to the modern practice of geomorphology where researchers have used decimeter resolution digital elevation models (DEMs) to determine the spatial frequencies of evenly spaced features in terrain, and developed models and mathematical equations to explain how the terrain evolved to its present state and how it is expected to change in the future (Perron et al., 2009). In geodynamics researchers have used ';before' and ';after' geodetic images of the terrain near earthquakes, such as the 2010 El Mayor-Cucapah Earthquake, to quantify surface displacements and suggest models to explain the observed deformations (Oskin et. al., 2012). In archaeology, the ability of ALS to produce ';bare earth' DEMs of terrain covered with dense vegetation, including even tropical rain forests, has revolutionized the study of archaeology in highly forested areas, finding ancient structures and human modifications of landscapes not discovered by archaeologists working at sites for decades (Chase et al., 2011 & Evans et al., 2013), and finding previously unknown ruins in areas that ground exploration has not been able to penetrate since the arrival of the conquistadors in the new world in the 17th century (Carter et al., 2012). The improved spatial resolution and ability of the third generation ALS units to obtain high resolution bare earth DEMs and canopy models in areas covered in dense forests, brush, and even shallow water (steams, lakes, and

Deducing the reachable space from fingertip positions.

Science.gov (United States)

Hai-Trieu Pham; Pathirana, Pubudu N

2015-01-01

The reachable space of the hand has received significant interests in the past from relevant medical researchers and health professionals. The reachable space was often computed from the joint angles acquired from a motion capture system such as gloves or markers attached to each bone of the finger. However, the contact between the hand and device can cause difficulties particularly for hand with injuries, burns or experiencing certain dermatological conditions. This paper introduces an approach to find the reachable space of the hand in a non-contact measurement form utilizing the Leap Motion Controller. The approach is based on the analysis of each position in the motion path of the fingertip acquired by the Leap Motion Controller. For each position of the fingertip, the inverse kinematic problem was solved under the physiological multiple constraints of the human hand to find a set of all possible configurations of three finger joints. Subsequently, all the sets are unified to form a set of all possible configurations specific for that motion. Finally, a reachable space is computed from the configuration corresponding to the complete extension and the complete flexion of the finger joint angles in this set.

First-order design of geodetic networks using the simulated annealing method

Science.gov (United States)

Berné, J. L.; Baselga, S.

2004-09-01

The general problem of the optimal design for a geodetic network subject to any extrinsic factors, namely the first-order design problem, can be dealt with as a numeric optimization problem. The classic theory of this problem and the optimization methods are revised. Then the innovative use of the simulated annealing method, which has been successfully applied in other fields, is presented for this classical geodetic problem. This method, belonging to iterative heuristic techniques in operational research, uses a thermodynamical analogy to crystalline networks to offer a solution that converges probabilistically to the global optimum. Basic formulation and some examples are studied.

Characterization of Ground Displacement Sources from Variational Bayesian Independent Component Analysis of Space Geodetic Time Series

Science.gov (United States)

Gualandi, Adriano; Serpelloni, Enrico; Elina Belardinelli, Maria; Bonafede, Maurizio; Pezzo, Giuseppe; Tolomei, Cristiano

2015-04-01

A critical point in the analysis of ground displacement time series, as those measured by modern space geodetic techniques (primarly continuous GPS/GNSS and InSAR) is the development of data driven methods that allow to discern and characterize the different sources that generate the observed displacements. A widely used multivariate statistical technique is the Principal Component Analysis (PCA), which allows to reduce the dimensionality of the data space maintaining most of the variance of the dataset explained. It reproduces the original data using a limited number of Principal Components, but it also shows some deficiencies, since PCA does not perform well in finding the solution to the so-called Blind Source Separation (BSS) problem. The recovering and separation of the different sources that generate the observed ground deformation is a fundamental task in order to provide a physical meaning to the possible different sources. PCA fails in the BSS problem since it looks for a new Euclidean space where the projected data are uncorrelated. Usually, the uncorrelation condition is not strong enough and it has been proven that the BSS problem can be tackled imposing on the components to be independent. The Independent Component Analysis (ICA) is, in fact, another popular technique adopted to approach this problem, and it can be used in all those fields where PCA is also applied. An ICA approach enables us to explain the displacement time series imposing a fewer number of constraints on the model, and to reveal anomalies in the data such as transient deformation signals. However, the independence condition is not easy to impose, and it is often necessary to introduce some approximations. To work around this problem, we use a variational bayesian ICA (vbICA) method, which models the probability density function (pdf) of each source signal using a mix of Gaussian distributions. This technique allows for more flexibility in the description of the pdf of the sources

Comparison between geodetic and oceanographic approaches to estimate mean dynamic topography for vertical datum unification: evaluation at Australian tide gauges

Science.gov (United States)

Filmer, M. S.; Hughes, C. W.; Woodworth, P. L.; Featherstone, W. E.; Bingham, R. J.

2018-04-01

The direct method of vertical datum unification requires estimates of the ocean's mean dynamic topography (MDT) at tide gauges, which can be sourced from either geodetic or oceanographic approaches. To assess the suitability of different types of MDT for this purpose, we evaluate 13 physics-based numerical ocean models and six MDTs computed from observed geodetic and/or ocean data at 32 tide gauges around the Australian coast. We focus on the viability of numerical ocean models for vertical datum unification, classifying the 13 ocean models used as either independent (do not contain assimilated geodetic data) or non-independent (do contain assimilated geodetic data). We find that the independent and non-independent ocean models deliver similar results. Maximum differences among ocean models and geodetic MDTs reach >150 mm at several Australian tide gauges and are considered anomalous at the 99% confidence level. These differences appear to be of geodetic origin, but without additional independent information, or formal error estimates for each model, some of these errors remain inseparable. Our results imply that some ocean models have standard deviations of differences with other MDTs (using geodetic and/or ocean observations) at Australian tide gauges, and with levelling between some Australian tide gauges, of ˜ ± 50 mm . This indicates that they should be considered as an alternative to geodetic MDTs for the direct unification of vertical datums. They can also be used as diagnostics for errors in geodetic MDT in coastal zones, but the inseparability problem remains, where the error cannot be discriminated between the geoid model or altimeter-derived mean sea surface.

An attempt to evaluate horizontal crustal movement by geodetic and geological approach in the Horonobe area, Northern Hokkaido, Japan

International Nuclear Information System (INIS)

Tokiwa, Tetsuya; Niizato, Tadafumi; Nohara, Tsuyoshi; Asamori, Koichi; Matsuura, Yuki; Kosaka, Hideki

2011-01-01

In this study, we present the preliminary results for the estimation of a horizontal crustal movement by using geodetic and geological approach in the Horonobe area, northern Hokkaido, Japan. The estimations have been carried out by using a GPS data and a geological cross section obtained by applying balanced-section method. As results of this study, both of the shortening rates estimated by GPS data and balanced-section method indicate several millimeters per year. Namely, there is no contradiction between geodetic and geological data, and it is considered that Horonobe area is still situated similar tendency and magnitude of a crustal movement. It is seemingly considered that geodetic data is unhelpful for estimating the long-term crustal movement, because period of geodetic observations is a very short. However, the result of this study indicates that geodetic data provide valuable information for estimating the long-term crustal movement in the area, and it is considered that geodetic approach play an important role in improvement of the credibility of evaluation for prediction of long-term stability. (author)

Aftershock distribution as a constraint on the geodetic model of coseismic slip for the 2004 Parkfield earthquake

Science.gov (United States)

Bennington, Ninfa; Thurber, Clifford; Feigl, Kurt; ,

2011-01-01

Several studies of the 2004 Parkfield earthquake have linked the spatial distribution of the event’s aftershocks to the mainshock slip distribution on the fault. Using geodetic data, we find a model of coseismic slip for the 2004 Parkfield earthquake with the constraint that the edges of coseismic slip patches align with aftershocks. The constraint is applied by encouraging the curvature of coseismic slip in each model cell to be equal to the negative of the curvature of seismicity density. The large patch of peak slip about 15 km northwest of the 2004 hypocenter found in the curvature-constrained model is in good agreement in location and amplitude with previous geodetic studies and the majority of strong motion studies. The curvature-constrained solution shows slip primarily between aftershock “streaks” with the continuation of moderate levels of slip to the southeast. These observations are in good agreement with strong motion studies, but inconsistent with the majority of published geodetic slip models. Southeast of the 2004 hypocenter, a patch of peak slip observed in strong motion studies is absent from our curvature-constrained model, but the available GPS data do not resolve slip in this region. We conclude that the geodetic slip model constrained by the aftershock distribution fits the geodetic data quite well and that inconsistencies between models derived from seismic and geodetic data can be attributed largely to resolution issues.

Operational space weather service for GNSS precise positioning

Directory of Open Access Journals (Sweden)

N. Jakowski

2005-11-01

Full Text Available The ionospheric plasma can significantly influence the propagation of radio waves and the ionospheric disturbances are capable of causing range errors, rapid phase and amplitude fluctuations (radio scintillations of satellite signals that may lead to degradation of the system performance, its accuracy and reliability. The cause of such disturbances should be sought in the processes originating in the Sun. Numerous studies on these phenomena have been already carried out at a broad international level, in order to measure/estimate these space weather induced effects, to forecast them, and to understand and mitigate their impact on present-day technological systems. SWIPPA (Space Weather Impact on Precise Positioning Applications is a pilot project jointly supported by the German Aerospace Centre (DLR and the European Space Agency (ESA. The project aims at establishing, operating, and evaluating a specific space-weather monitoring service that can possibly lead to improving current positioning applications based on Global Navigation Satellite Systems (GNSS. This space weather service provides GNSS users with essential expert information delivered in the form of several products - maps of TEC values, TEC spatial and temporal gradients, alerts for ongoing/oncoming ionosphere disturbances, etc.

Operational space weather service for GNSS precise positioning

Directory of Open Access Journals (Sweden)

N. Jakowski

2005-11-01

Full Text Available The ionospheric plasma can significantly influence the propagation of radio waves and the ionospheric disturbances are capable of causing range errors, rapid phase and amplitude fluctuations (radio scintillations of satellite signals that may lead to degradation of the system performance, its accuracy and reliability. The cause of such disturbances should be sought in the processes originating in the Sun. Numerous studies on these phenomena have been already carried out at a broad international level, in order to measure/estimate these space weather induced effects, to forecast them, and to understand and mitigate their impact on present-day technological systems.

SWIPPA (Space Weather Impact on Precise Positioning Applications is a pilot project jointly supported by the German Aerospace Centre (DLR and the European Space Agency (ESA. The project aims at establishing, operating, and evaluating a specific space-weather monitoring service that can possibly lead to improving current positioning applications based on Global Navigation Satellite Systems (GNSS. This space weather service provides GNSS users with essential expert information delivered in the form of several products - maps of TEC values, TEC spatial and temporal gradients, alerts for ongoing/oncoming ionosphere disturbances, etc.

NEAR REAL-TIME DETERMINATION OF EARTHQUAKE SOURCE PARAMETERS FOR TSUNAMI EARLY WARNING FROM GEODETIC OBSERVATIONS

Directory of Open Access Journals (Sweden)

S. Manneela

2016-06-01

Full Text Available Exemplifying the tsunami source immediately after an earthquake is the most critical component of tsunami early warning, as not every earthquake generates a tsunami. After a major under sea earthquake, it is very important to determine whether or not it has actually triggered the deadly wave. The near real-time observations from near field networks such as strong motion and Global Positioning System (GPS allows rapid determination of fault geometry. Here we present a complete processing chain of Indian Tsunami Early Warning System (ITEWS, starting from acquisition of geodetic raw data, processing, inversion and simulating the situation as it would be at warning center during any major earthquake. We determine the earthquake moment magnitude and generate the centroid moment tensor solution using a novel approach which are the key elements for tsunami early warning. Though the well established seismic monitoring network, numerical modeling and dissemination system are currently capable to provide tsunami warnings to most of the countries in and around the Indian Ocean, the study highlights the critical role of geodetic observations in determination of tsunami source for high-quality forecasting.

Uvođenje novih geodetskih referentnih sistema u Bosni i Hercegovini : Introduction of a new geodetic reference systems in Bosnia and Herzegovina

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Šeho Zimić

2017-12-01

Full Text Available The introduction of a new reference system in Bosnia and Herzegovina is not only a necessity, but an obligation imposed by the United Nations (UN and the European Union (EU. At the General Assembly on February 26, 2015, the UN has adopted a resolution titled "Global Geodetic Reference Frame for Sustainable Development - GGRF", which for the first time raise the geodetic issue as a political issue at such a high level. The resolution highlights the strong need for more precise positioning and navigation from the use of smartphones to the study of climate changes, population migrations and other scientific researches of relevance to the whole world (http://www.unggrf.org/. All this is not possible without a global exchange of geodata and a common global geodetic reference system. Through the Inspire Directive, the EU has clearly specified which coordinate and heights systems are being applied in Europe. The countries in the region have adopted the European terrestrial reference system ETRS89 as a new reference system in their legislation. Through the EUREF campaign BALKAN98 and the introduction of the Network of permanent GNSS stations Bosnia and Herzegovina has joined the famil

3D geodetic monitoring slope deformations

Directory of Open Access Journals (Sweden)

Weiss Gabriel

1996-06-01

Full Text Available For plenty of slope failures that can be found in Slovakia is necessary and very important their geodetic monitoring (because of their activity, reactivisations, checks. The paper gives new methodologies for these works, using 3D terrestrial survey technologies for measurements in convenient deformation networks. The design of an optimal type of deformation model for various kinds of landslides and their exact processing with an efficient testing procedure to determine the kinematics of the slope deformations are presented too.

Seismic and Geodetic Monitoring of the Nicoya, Costa Rica, Seismic Gap

Science.gov (United States)

Protti, M.; Gonzalez, V.; Schwartz, S.; Dixon, T.; Kato, T.; Kaneda, Y.; Simila, G.; Sampson, D.

2007-05-01

The Nicoya segment of the Middle America Trench has been recognized as a mature seismic gap with potential to generate a large earthquake in the near future (it ruptured with large earthquakes in 1853, 1900 and 1950). Low level of background seismicity and fast crustal deformation of the forearc are indicatives of strong coupling along the plate interface. Given its high seismic potential, the available data and especially the fact that the Nicoya peninsula extends over large part of the rupture area, this gap was selected as one of the two sites for a MARGINS-SEIZE experiment. With the goal of documenting the evolution of loading and stress release along this seismic gap, an international effort involving several institutions from Costa Rica, the United States and Japan is being carried out for over a decade in the region. This effort involves the installation of temporary and permanent seismic and geodetic networks. The seismic network includes short period, broad band and strong motion instruments. The seismic monitoring has provided valuable information on the geometry and characteristics of the plate interface. The geodetic network includes temporary and permanent GPS stations as well as surface and borehole tiltmeters. The geodetic networks have helped quantify the extend and degree of coupling. A continuously recording, three- station GPS network on the Nicoya Peninsula, Costa Rica, recorded what we believe is the first slow slip event observed along the plate interface of the Costa Rica subduction zone. We will present results from these monitoring networks. Collaborative international efforts are focused on expanding these seismic and geodetic networks to provide improved resolution of future creep events, to enhanced understanding of the mechanical behavior of the Nicoya subduction segment of the Middle American Trench and possibly capture the next large earthquake and its potential precursor deformation.

Establishment of 2000 National Geodetic Control Network of China and It’s Technological Progress

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CHEN Junyong

2007-02-01

Full Text Available Objectives: 2000’ National Geodetic Control Network of China is an important fundamental scientific engineering project in China. It consists of three parts which are establishment of 2000 National GPS Geodetic Network, its combination adjustment with national astro-geodetic network and 2000 National Gravity Fundamental network. It provides the high precise coordinate reference and gravity reference for three dimensional geo-center national coordinates system and gravity system, respectively. Additionally, it provides precise unified geometric and physical geodesy information for the economic construction, the national defense and the scientific research. Methods: 1. The larger number of data are processed in triple networks adjustment of 2000 National GPS Geodetic Network, which are chosen from the GPS monitoring stations, such as grade A, B of national GPS network , grade 1st and 2nd of national GPS network, crustal movement observation network of China, and others crustal deformation monitoring stations. Finally, the data of 2666 GPS stations are used in the data processing of 2000 National GPS Geodetic Network, including 124 external stations and 2542 internal stations. In order to the results of triple networks adjustment are corresponding to that of three dimensional geo-center coordinates system, ITRF 97 and epoch 2000.0 are chosen as the coordinate reference frame and epoch reference, respectively. The methods of “strong reference” and “weak reference” are combined used in the control data selection of triple networks adjustment. The scale and rotation scales are adopted for each sub network. The least square adjustment is firstly adopted in each sub network adjustment. The data of obvious abnormal baselines are found and rejected firstly. And the method of double factor robust estimation is adopted in the data processing. 2. The combined adjustment of 2000 National GPS Geodetic Network and national astro-geodetic network is

An Investigation on the Use of Different Centroiding Algorithms and Star Catalogs in Astro-Geodetic Observations

Science.gov (United States)

Basoglu, Burak; Halicioglu, Kerem; Albayrak, Muge; Ulug, Rasit; Tevfik Ozludemir, M.; Deniz, Rasim

2017-04-01

In the last decade, the importance of high-precise geoid determination at local or national level has been pointed out by Turkish National Geodesy Commission. The Commission has also put objective of modernization of national height system of Turkey to the agenda. Meanwhile several projects have been realized in recent years. In Istanbul city, a GNSS/Levelling geoid was defined in 2005 for the metropolitan area of the city with an accuracy of ±3.5cm. In order to achieve a better accuracy in this area, "Local Geoid Determination with Integration of GNSS/Levelling and Astro-Geodetic Data" project has been conducted in Istanbul Technical University and Bogazici University KOERI since January 2016. The project is funded by The Scientific and Technological Research Council of Turkey. With the scope of the project, modernization studies of Digital Zenith Camera System are being carried on in terms of hardware components and software development. Accentuated subjects are the star catalogues, and centroiding algorithm used to identify the stars on the zenithal star field. During the test observations of Digital Zenith Camera System performed between 2013-2016, final results were calculated using the PSF method for star centroiding, and the second USNO CCD Astrograph Catalogue (UCAC2) for the reference star positions. This study aims to investigate the position accuracy of the star images by comparing different centroiding algorithms and available star catalogs used in astro-geodetic observations conducted with the digital zenith camera system.

Contribution of SELENE-2 geodetic measurements to constrain the lunar internal structure

Science.gov (United States)

Matsumoto, K.; Kikuchi, F.; Yamada, R.; Iwata, T.; Kono, Y.; Tsuruta, S.; Hanada, H.; Goossens, S. J.; Ishihara, Y.; Kamata, S.; Sasaki, S.

2012-12-01

anticipated k2 accuracy. With the assumed mission duration of about 3 months and the arc length of 14 days, the k2 accuracy is estimated to be better than 1 %, where the uncertainty is evaluated as 10 times the formal error considering the errors in the non-conservative force modeling and in the lander position. We carried out a feasibility study using Bayesian inversion on how well we can constrain the lunar internal structure by the geodetic data to be improved by SELENE-2. It will be shown that such improved geodetic data contribute to narrow the range of the plausible internal structure models, but there are still trade-offs among crust, mantle, and core structures. Preliminary simulation results will be presented to show that the accuracy of core structure estimation will be improved in consequence of better determination of the mantle structure by combining the geodetic data with the seismic data. References [1] Weber et al. (2011), Science, 331, 309-312, doi:10.1126/science.1199375 [2] Garcia eta l. (2011), PEPI, doi:10.1016/j.pepi.2011.06.015 [3] Williams et al. (2001), JGR, 106, E11, 27,933-27,968 [4] Khan and Mosegaard (2005), GRL, 32, L22203, doi:10.1029/2005GL023985

A position-dependent mass harmonic oscillator and deformed space

Science.gov (United States)

da Costa, Bruno G.; Borges, Ernesto P.

2018-04-01

We consider canonically conjugated generalized space and linear momentum operators x^ q and p^ q in quantum mechanics, associated with a generalized translation operator which produces infinitesimal deformed displacements controlled by a deformation parameter q. A canonical transformation (x ^ ,p ^ ) →(x^ q,p^ q ) leads the Hamiltonian of a position-dependent mass particle in usual space to another Hamiltonian of a particle with constant mass in a conservative force field of the deformed space. The equation of motion for the classical phase space (x, p) may be expressed in terms of the deformed (dual) q-derivative. We revisit the problem of a q-deformed oscillator in both classical and quantum formalisms. Particularly, this canonical transformation leads a particle with position-dependent mass in a harmonic potential to a particle with constant mass in a Morse potential. The trajectories in phase spaces (x, p) and (xq, pq) are analyzed for different values of the deformation parameter. Finally, we compare the results of the problem in classical and quantum formalisms through the principle of correspondence and the WKB approximation.

MOONLIGHT: A NEW LUNAR LASER RANGING RETROREFLECTOR AND THE LUNAR GEODETIC PRECESSION

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M. Martini

2013-12-01

Full Text Available Since the 1970s Lunar Laser Ranging (LLR to the Apollo Cube Corner Retroreflector (CCR arrays (developed by the University of Maryland, UMD supplied almost all significant tests of General Relativity (Alley et al., 1970; Chang et al., 1971; Bender et al.,1973: possible changes in the gravitational constant, gravitational self-energy, weak equivalence principle, geodetic precession, inverse-square force-law. The LNF group, in fact, has just completed a new measurement of the lunar geodetic precession with Apollo array, with accuracy of 9 × 10−3, comparable to the best measurement to date. LLR has also provided significant information on the composition and origin of the moon. This is the only Apollo experiment still in operation. In the 1970s Apollo LLR arrays contributed a negligible fraction of the ranging error budget. Since the ranging capabilities of ground stations improved by more than two orders of magnitude, now, because of the lunar librations, Apollo CCR arrays dominate the error budget. With the project MoonLIGHT (Moon Laser Instrumentation for General relativity High-accuracy Tests, in 2006 INFN-LNF joined UMD in the development and test of a new-generation LLR payload made by a single, large CCR (100mm diameter unaffected by the effect of librations. With MoonLIGHT CCRs the accuracy of the measurement of the lunar geodetic precession can be improved up to a factor 100 compared to Apollo arrays. From a technological point of view, INFN-LNF built and is operating a new experimental apparatus (Satellite/lunar laser ranging Characterization Facility, SCF and created a new industry-standard test procedure (SCF-Test to characterize and model the detailed thermal behavior and the optical performance of CCRs in accurately laboratory-simulated space conditions, for industrial and scientific applications. Our key experimental innovation is the concurrent measurement and modeling of the optical Far Field Diffraction Pattern (FFDP and the

POSITION DETERMINATION OF CLOSELY SPACED BUNCHES USING CAVITY BPMs

CERN Document Server

Joshi, N; Cullinan, F; Lyapin, A

2011-01-01

Radio Frequency (RF) Cavity Beam Position Monitor (BPM) systems form a major part of precision position measurement diagnostics for linear accelerators with low emittance beams. Using cavity BPMs, a position resolution of less than 100 nm has been demonstrated in single bunch mode operation. In the case of closely spaced bunches, where the decay time of the cavity is comparable to the time separation between bunches, the BPM signal from a bunch is polluted by the signal induced by the previous bunches in the same bunch-train. This paper discusses our ongoing work to develop the methods to extract the position of closely spaced bunches using cavity BPMs. A signal subtraction code is being developed to remove the signal pollution from previous bunches and to determine the individual bunch position. Another code has been developed to simulate the BPM data for the cross check. Performance of the code is studied on the experimental and simulated data. Application of the analysis techniques to the linear colliders,...

Assessment of the possible contribution of space ties on-board GNSS satellites to the terrestrial reference frame

Science.gov (United States)

Bruni, Sara; Rebischung, Paul; Zerbini, Susanna; Altamimi, Zuheir; Errico, Maddalena; Santi, Efisio

2018-04-01

The realization of the international terrestrial reference frame (ITRF) is currently based on the data provided by four space geodetic techniques. The accuracy of the different technique-dependent materializations of the frame physical parameters (origin and scale) varies according to the nature of the relevant observables and to the impact of technique-specific errors. A reliable computation of the ITRF requires combining the different inputs, so that the strengths of each technique can compensate for the weaknesses of the others. This combination, however, can only be performed providing some additional information which allows tying together the independent technique networks. At present, the links used for that purpose are topometric surveys (local/terrestrial ties) available at ITRF sites hosting instruments of different techniques. In principle, a possible alternative could be offered by spacecrafts accommodating the positioning payloads of multiple geodetic techniques realizing their co-location in orbit (space ties). In this paper, the GNSS-SLR space ties on-board GPS and GLONASS satellites are thoroughly examined in the framework of global reference frame computations. The investigation focuses on the quality of the realized physical frame parameters. According to the achieved results, the space ties on-board GNSS satellites cannot, at present, substitute terrestrial ties in the computation of the ITRF. The study is completed by a series of synthetic simulations investigating the impact that substantial improvements in the volume and quality of SLR observations to GNSS satellites would have on the precision of the GNSS frame parameters.

DETECTION OF COASTLINE DEFORMATION USING REMOTE SENSING AND GEODETIC SURVEYS

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A. Sabuncu

2016-06-01

Full Text Available The coastal areas are being destroyed due to the usage that effect the natural balance. Unconsciously sand mining from the sea for nearshore nourishment and construction uses are the main ones. Physical interferences for mining of sand cause an ecologic threat to the coastal environment. However, use of marine sand is inevitable because of economic reasons or unobtainable land-based sand resources. The most convenient solution in such a protection–usage dilemma is to reduce negative impacts of sand production from marine. This depends on the accurate determination of criteriaon production place, style, and amount of sand. With this motivation, nearshore geodedic surveying studies performed on Kilyos Campus of Bogazici University located on the Black Sea coast, north of Istanbul, Turkey between 2001-2002. The study area extends 1 km in the longshore. Geodetic survey was carried out in the summer of 2001 to detect the initial condition for the shoreline. Long-term seasonal changes in shoreline positions were determined biannually. The coast was measured with post-processed kinematic GPS. Besides, shoreline change has studied using Landsat imagery between the years 1986-2015. The data set of Landsat 5 imageries were dated 05.08.1986 and 31.08.2007 and Landsat 7 imageries were dated 21.07.2001 and 28.07.2015. Landcover types in the study area were analyzed on the basis of pixel based classification method. Firstly, unsupervised classification based on ISODATA (Iterative Self Organizing Data Analysis Technique has been applied and spectral clusters have been determined that gives prior knowledge about the study area. In the second step, supervised classification was carried out by using the three different approaches which are minimum-distance, parallelepiped and maximum-likelihood. All pixel based classification processes were performed with ENVI 4.8 image processing software. Results of geodetic studies and classification outputs will be

Field Installation and Real-Time Data Processing of the New Integrated SeismoGeodetic System with Real-Time Acceleration and Displacement Measurements for Earthquake Characterization Based on High-Rate Seismic and GPS Data

Science.gov (United States)

Zimakov, Leonid; Jackson, Michael; Passmore, Paul; Raczka, Jared; Alvarez, Marcos; Barrientos, Sergio

2015-04-01

We will discuss and show the results obtained from an integrated SeismoGeodetic System, model SG160-09, installed in the Chilean National Network. The SG160-09 provides the user high rate GNSS and accelerometer data, full epoch-by-epoch measurement integrity and, using the Trimble Pivot™ SeismoGeodetic App, the ability to create combined GNSS and accelerometer high-rate (200Hz) displacement time series in real-time. The SG160-09 combines seismic recording with GNSS geodetic measurement in a single compact, ruggedized package. The system includes a low-power, 220-channel GNSS receiver powered by the latest Trimble-precise Maxwell™6 technology and supports tracking GPS, GLONASS and Galileo signals. The receiver incorporates on-board GNSS point positioning using Real-Time Precise Point Positioning (PPP) technology with satellite clock and orbit corrections delivered over IP networks. The seismic recording element includes an ANSS Class A, force balance triaxial accelerometer with the latest, low power, 24-bit A/D converter, which produces high-resolution seismic data. The SG160-09 processor acquires and packetizes both seismic and geodetic data and transmits it to the central station using an advanced, error-correction protocol with back fill capability providing data integrity between the field and the processing center. The SG160-09 has been installed in the seismic station close to the area of the Iquique earthquake of April 1, 2014, in northern Chile, a seismically prone area at the current time. The hardware includes the SG160-09 system, external Zephyr Geodetic-2 GNSS antenna, and high-speed Internet communication media. Both acceleration and displacement data was transmitted in real-time to the National Seismological Center in Santiago for real-time data processing using Earthworm / Early Bird software. Command/Control of the field station and real-time GNSS position correction are provided via the Pivot software suite. Data from the SG160-09 system was

Geodetic determinations for the NuMI project at Fermilab

International Nuclear Information System (INIS)

Bocean, V.

1999-01-01

As a part of the Neutrinos at the Main Injector (NuMI) project, the MINOS (Main Injector Neutrino Oscillation Search) experiment will search for neutrino mass by looking for neutrino oscillations. The project plans to direct a beam of muon neutrinos from the Main Injector towards both nearby and far-off detectors capable of counting all three types of neutrinos. The beam will travel 735 km through the Earth towards a remote iron mine in northern Minnesota where, 710 m below surface, a massive 5400 metric tons detector will be built. For the neutrino energy spectrum physics test to work properly, the primary proton beam must be within ± 12 m from its ideal position at Soudan, MN, corresponding to ± 1.63 x 10-5 radians, i.e. 3.4 arc-seconds. Achieving this tolerance requires a rather exact knowledge of the geometry of the beam, expressed in terms of the azimuth and the slope of the vector joining the two sites. This paper summarizes the concepts, the methodology, the implementation, and the results of the geodetic surveying efforts made up to date for determining the absolute positions of the Fermilab and the Soudan underground mine sites, from which the beam orientation parameters are computed. (author)

A comparative study for the estimation of geodetic point velocity by ...

Indian Academy of Sciences (India)

Geodetic point velocity; artificial neural networks; back propagation; radial basis function; Kriging. J. Earth Syst. Sci. ...... The employment of BPANN is an alternative tool to KRIG for .... Computational Intelligence and Multimedia Applications.

Geodetic and seismological investigation in the Ionian area

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F. Riguzzi

1997-06-01

Full Text Available Geodetic and seismic evidence of crustal deformations in the Ionian area are shown in this paper. The Ionian GPS network, composed of nine sites crossing the Ionian Sea from Calabria, Southern Italy, to Northwestern Greece, was established and surveyed in 1991, 1994, 1995 within the framework of the TYRGEONET project (Anzidei et al., 1996. In 1996 a return campaign was carried out after the occurrence of seismic activity in 1995. The displacement pattern obtained for the Greek side of the network agrees well with those previously displayed, both in magnitude and direction, confirming a mean displacement rate of about 1-2 cm1/yr. The same agreement is not found for the Italian side of the network, where no significant deformations were detected between 1994 and 1996. Seismic deformation was also studied for the same area, starting from the moment tensors of events which occurred in the last 20 years with magnitude greater than 5.0; evident similarity with the displacement field exhibited by the Greek side of the Ionian Sea by geodetic surveys was inferred. On the contrary, the motion detected for the Italian area cannot be simply related to seismic activity.

The Impact of Sea Level Rise on Geodetic Vertical Datum of Peninsular Malaysia

Science.gov (United States)

Din, A. H. M.; Abazu, I. C.; Pa'suya, M. F.; Omar, K. M.; Hamid, A. I. A.

2016-09-01

Sea level rise is rapidly turning into major issues among our community and all levels of the government are working to develop responses to ensure these matters are given the uttermost attention in all facets of planning. It is more interesting to understand and investigate the present day sea level variation due its potential impact, particularly on our national geodetic vertical datum. To determine present day sea level variation, it is vital to consider both in-situ tide gauge and remote sensing measurements. This study presents an effort to quantify the sea level rise rate and magnitude over Peninsular Malaysia using tide gauge and multi-mission satellite altimeter. The time periods taken for both techniques are 32 years (from 1984 to 2015) for tidal data and 23 years (from 1993 to 2015) for altimetry data. Subsequently, the impact of sea level rise on Peninsular Malaysia Geodetic Vertical Datum (PMGVD) is evaluated in this study. the difference between MSL computed from 10 years (1984 - 1993) and 32 years (1984 - 2015) tidal data at Port Kelang showed that the increment of sea level is about 27mm. The computed magnitude showed an estimate of the long-term effect a change in MSL has on the geodetic vertical datum of Port Kelang tide gauge station. This will help give a new insight on the establishment of national geodetic vertical datum based on mean sea level data. Besides, this information can be used for a wide variety of climatic applications to study environmental issues related to flood and global warming in Malaysia.

THE IMPACT OF SEA LEVEL RISE ON GEODETIC VERTICAL DATUM OF PENINSULAR MALAYSIA

Directory of Open Access Journals (Sweden)

A. H. M. Din

2016-09-01

Full Text Available Sea level rise is rapidly turning into major issues among our community and all levels of the government are working to develop responses to ensure these matters are given the uttermost attention in all facets of planning. It is more interesting to understand and investigate the present day sea level variation due its potential impact, particularly on our national geodetic vertical datum. To determine present day sea level variation, it is vital to consider both in-situ tide gauge and remote sensing measurements. This study presents an effort to quantify the sea level rise rate and magnitude over Peninsular Malaysia using tide gauge and multi-mission satellite altimeter. The time periods taken for both techniques are 32 years (from 1984 to 2015 for tidal data and 23 years (from 1993 to 2015 for altimetry data. Subsequently, the impact of sea level rise on Peninsular Malaysia Geodetic Vertical Datum (PMGVD is evaluated in this study. the difference between MSL computed from 10 years (1984 – 1993 and 32 years (1984 – 2015 tidal data at Port Kelang showed that the increment of sea level is about 27mm. The computed magnitude showed an estimate of the long-term effect a change in MSL has on the geodetic vertical datum of Port Kelang tide gauge station. This will help give a new insight on the establishment of national geodetic vertical datum based on mean sea level data. Besides, this information can be used for a wide variety of climatic applications to study environmental issues related to flood and global warming in Malaysia.

Demonstration of the Cascadia G‐FAST geodetic earthquake early warning system for the Nisqually, Washington, earthquake

Science.gov (United States)

Crowell, Brendan; Schmidt, David; Bodin, Paul; Vidale, John; Gomberg, Joan S.; Hartog, Renate; Kress, Victor; Melbourne, Tim; Santillian, Marcelo; Minson, Sarah E.; Jamison, Dylan

2016-01-01

A prototype earthquake early warning (EEW) system is currently in development in the Pacific Northwest. We have taken a two‐stage approach to EEW: (1) detection and initial characterization using strong‐motion data with the Earthquake Alarm Systems (ElarmS) seismic early warning package and (2) the triggering of geodetic modeling modules using Global Navigation Satellite Systems data that help provide robust estimates of large‐magnitude earthquakes. In this article we demonstrate the performance of the latter, the Geodetic First Approximation of Size and Time (G‐FAST) geodetic early warning system, using simulated displacements for the 2001Mw 6.8 Nisqually earthquake. We test the timing and performance of the two G‐FAST source characterization modules, peak ground displacement scaling, and Centroid Moment Tensor‐driven finite‐fault‐slip modeling under ideal, latent, noisy, and incomplete data conditions. We show good agreement between source parameters computed by G‐FAST with previously published and postprocessed seismic and geodetic results for all test cases and modeling modules, and we discuss the challenges with integration into the U.S. Geological Survey’s ShakeAlert EEW system.

Evidences of the expanding Earth from space-geodetic data over solid land and sea level rise in recent two decades

Directory of Open Access Journals (Sweden)

Wenbin Shen

2015-07-01

Full Text Available According to the space-geodetic data recorded at globally distributed stations over solid land spanning a period of more than 20-years under the International Terrestrial Reference Frame 2008, our previous estimate of the average-weighted vertical variation of the Earth's solid surface suggests that the Earth's solid part is expanding at a rate of 0.24 ± 0.05 mm/a in recent two decades. In another aspect, the satellite altimetry observations spanning recent two decades demonstrate the sea level rise (SLR rate 3.2 ± 0.4 mm/a, of which 1.8 ± 0.5 mm/a is contributed by the ice melting over land. This study shows that the oceanic thermal expansion is 1.0 ± 0.1 mm/a due to the temperature increase in recent half century, which coincides with the estimate provided by previous authors. The SLR observation by altimetry is not balanced by the ice melting and thermal expansion, which is an open problem before this study. However, in this study we infer that the oceanic part of the Earth is expanding at a rate about 0.4 mm/a. Combining the expansion rates of land part and oceanic part, we conclude that the Earth is expanding at a rate of 0.35 ± 0.47 mm/a in recent two decades. If the Earth expands at this rate, then the altimetry-observed SLR can be well explained.

Using geodetic data to infer the kinematic and mechanical properties of deformation sources on Kilauea Volcano, Hawaii

Science.gov (United States)

Cervelli, Peter Francis

2002-09-01

Paradoxically, one of the greatest hazards associated with oceanic volcanoes is not volcanic. Rather, it is the potential for catastrophic flank failure resulting in devastating tsunamis, which threaten not just the immediate vicinity, but coastal cities along the entire rim of an ocean basin. Kilauea volcano on the Island of Hawaii, USA, a potential source of such flank failures, is monitored by a network of continuously recording geodetic instruments, including Global Positioning System (GPS) receivers, tiltmeters, and strainmeters. In this thesis, methodology is developed for using these geodetic data to estimate the geometry and type of active deformation sources, such as dikes, magma chambers, and faults. The methodology is then applied to two episodes of deformation that occurred at Kilauea Volcano in 1999 and 2000. First, the deformation associated with an earthquake swarm on September 12, 1999 in the Upper East Rift Zone of Kilauea Volcano, which was recorded by continuous GPS receivers, tiltmeters, campaign GPS, leveling, and InSAR, is analyzed and interpreted as a west to east propagating dike intrusion. Lack of premonitory inflation of Kilauea's summit suggests that the immediate cause of the intrusion was probably tensile failure in the shallow crust of the Upper East Rift, rather than forceful magma injection. Second, in early November 2000, the geodetic network recorded transient southeastward displacements, which we interpret as an episode of aseismic fault slip. The duration of the event was about 36 hours; it had an equivalent moment magnitude of M5.7, and a maximum slip velocity of about 6 cm/day. Inversion of the GPS data images a shallowly dipping thrust at a depth of 4.5 km that we interpret as the down dip extension of the Hilina Pali fault system. Thus it is demonstrated that continuous geodetic networks can detect accelerating slip, potentially leading to warnings of imminent volcanic flank collapse. Finally, in the last chapter of the

Sun position calculator (SPC) for Landsat imagery with geodetic latitudes

Science.gov (United States)

Seong, Jeong C.

2015-12-01

Landsat imagery comes with sun position information such as azimuth and sun elevation, but they are available only at the center of a scene. To aid in the use of Landsat imagery for various solar radiation applications such as topographic correction, solar power, urban heat island, agriculture, climate and vegetation, it is necessary to calculate the sun position information at every pixel. This research developed a PC application that creates sun position data layers in ArcGIS at every pixel in a Landsat scene. The SPC program is composed of two major routines - converting universal transverse Mercator (UTM) projection coordinates to geographic longitudes and latitudes, and calculating sun position information based on the Meeus' routine. For the latter, an innovative method was also implemented to account for the Earth's flattening on an ellipsoid. The Meeus routine implemented in this research showed about 0.2‧ of mean absolute difference from the National Renewable Energy Laboratory (NREL) Solar Position Algorithm (SPA) routine when solar zenith and azimuth angles were tested with every 30 min data at four city locations (Fairbanks, Atlanta, Sydney and Rio Grande) on June 30, 2014. The Meeus routine was about ten times faster than the SPA routine. Professionals who need the Sun's position information for Landsat imagery will benefit from the SPC application.

A Comparison of Geodetic and Geologic Rates Prior to Large Strike-Slip Earthquakes: A Diversity of Earthquake-Cycle Behaviors?

Science.gov (United States)

Dolan, James F.; Meade, Brendan J.

2017-12-01

Comparison of preevent geodetic and geologic rates in three large-magnitude (Mw = 7.6-7.9) strike-slip earthquakes reveals a wide range of behaviors. Specifically, geodetic rates of 26-28 mm/yr for the North Anatolian fault along the 1999 MW = 7.6 Izmit rupture are ˜40% faster than Holocene geologic rates. In contrast, geodetic rates of ˜6-8 mm/yr along the Denali fault prior to the 2002 MW = 7.9 Denali earthquake are only approximately half as fast as the latest Pleistocene-Holocene geologic rate of ˜12 mm/yr. In the third example where a sufficiently long pre-earthquake geodetic time series exists, the geodetic and geologic rates along the 2001 MW = 7.8 Kokoxili rupture on the Kunlun fault are approximately equal at ˜11 mm/yr. These results are not readily explicable with extant earthquake-cycle modeling, suggesting that they may instead be due to some combination of regional kinematic fault interactions, temporal variations in the strength of lithospheric-scale shear zones, and/or variations in local relative plate motion rate. Whatever the exact causes of these variable behaviors, these observations indicate that either the ratio of geodetic to geologic rates before an earthquake may not be diagnostic of the time to the next earthquake, as predicted by many rheologically based geodynamic models of earthquake-cycle behavior, or different behaviors characterize different fault systems in a manner that is not yet understood or predictable.

Extending Resolution of Fault Slip With Geodetic Networks Through Optimal Network Design

Science.gov (United States)

Sathiakumar, Sharadha; Barbot, Sylvain Denis; Agram, Piyush

2017-12-01

Geodetic networks consisting of high precision and high rate Global Navigation Satellite Systems (GNSS) stations continuously monitor seismically active regions of the world. These networks measure surface displacements and the amount of geodetic strain accumulated in the region and give insight into the seismic potential. SuGar (Sumatra GPS Array) in Sumatra, GEONET (GNSS Earth Observation Network System) in Japan, and PBO (Plate Boundary Observatory) in California are some examples of established networks around the world that are constantly expanding with the addition of new stations to improve the quality of measurements. However, installing new stations to existing networks is tedious and expensive. Therefore, it is important to choose suitable locations for new stations to increase the precision obtained in measuring the geophysical parameters of interest. Here we describe a methodology to design optimal geodetic networks that augment the existing system and use it to investigate seismo-tectonics at convergent and transform boundaries considering land-based and seafloor geodesy. The proposed network design optimization would be pivotal to better understand seismic and tsunami hazards around the world. Land-based and seafloor networks can monitor fault slip around subduction zones with significant resolution, but transform faults are more challenging to monitor due to their near-vertical geometry.

Ostrogradski Hamiltonian approach for geodetic brane gravity

International Nuclear Information System (INIS)

Cordero, Ruben; Molgado, Alberto; Rojas, Efrain

2010-01-01

We present an alternative Hamiltonian description of a branelike universe immersed in a flat background spacetime. This model is named geodetic brane gravity. We set up the Regge-Teitelboim model to describe our Universe where such field theory is originally thought as a second order derivative theory. We refer to an Ostrogradski Hamiltonian formalism to prepare the system to its quantization. This approach comprize the manage of both first- and second-class constraints and the counting of degrees of freedom follows accordingly.

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

Science.gov (United States)

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.

Relativistic quantum similarities in atoms in position and momentum spaces

International Nuclear Information System (INIS)

Maldonado, P.; Sarsa, A.; Buendia, E.; Galvez, F.J.

2011-01-01

A study of different quantum similarity measures and their corresponding quantum similarity indices is carried out for the atoms from H to Lr (Z=1-103). Relativistic effects in both position and momentum spaces have been studied by comparing the relativistic values to the non-relativistic ones. We have used the atomic electron density in both position and momentum spaces obtained within relativistic and non-relativistic numerical-parameterized optimized effective potential approximations. -- Highlights: → Quantum similarity measures and indices in electronic structure of atoms. → Position and momentum electronic densities. → Similarity of relativistic and non-relativistic densities. → Similarity of core and valence regions of different atoms. → Dependence with Z along the Periodic Table.

GeoNetGIS: a Geodetic Network Geographical Information System to manage GPS networks in seismic and volcanic areas

Science.gov (United States)

Cristofoletti, P.; Esposito, A.; Anzidei, M.

2003-04-01

This paper presents the methodologies and issues involved in the use of GIS techniques to manage geodetic information derived from networks in seismic and volcanic areas. Organization and manipulation of different geodetical, geological and seismic database, give us a new challenge in interpretation of information that has several dimensions, including spatial and temporal variations, also the flexibility and brand range of tools available in GeoNetGIS, make it an attractive platform for earthquake risk assessment. During the last decade the use of geodetic networks based on the Global Positioning System, devoted to geophysical applications, especially for crustal deformation monitoring in seismic and volcanic areas, increased dramatically. The large amount of data provided by these networks, combined with different and independent observations, such as epicentre distribution of recent and historical earthquakes, geological and structural data, photo interpretation of aerial and satellite images, can aid for the detection and parameterization of seismogenic sources. In particular we applied our geodetic oriented GIS to a new GPS network recently set up and surveyed in the Central Apennine region: the CA-GeoNet. GeoNetGIS is designed to analyze in three and four dimensions GPS sources and to improve crustal deformation analysis and interpretation related with tectonic structures and seismicity. It manages many database (DBMS) consisting of different classes, such as Geodesy, Topography, Seismicity, Geology, Geography and Raster Images, administrated according to Thematic Layers. GeoNetGIS represents a powerful research tool allowing to join the analysis of all data layers to integrate the different data base which aid for the identification of the activity of known faults or structures and suggesting the new evidences of active tectonics. A new approach to data integration given by GeoNetGIS capabilities, allow us to create and deliver a wide range of maps, digital

RTX Correction Accuracy and Real-Time Data Processing of the New Integrated SeismoGeodetic System with Real-Time Acceleration and Displacement Measurements for Earthquake Characterization Based on High-Rate Seismic and GPS Data

Science.gov (United States)

Zimakov, L. G.; Raczka, J.; Barrientos, S. E.

2016-12-01

We will discuss and show the results obtained from an integrated SeismoGeodetic System, model SG160-09, installed in the Chile (Chilean National Network), Italy (University of Naples Network), and California. The SG160-09 provides the user high rate GNSS and accelerometer data, full epoch-by-epoch measurement integrity and the ability to create combined GNSS and accelerometer high-rate (200Hz) displacement time series in real-time. The SG160-09 combines seismic recording with GNSS geodetic measurement in a single compact, ruggedized case. The system includes a low-power, 220-channel GNSS receiver powered by the latest Trimble-precise Maxwell™6 technology and supports tracking GPS, GLONASS and Galileo signals. The receiver incorporates on-board GNSS point positioning using Real-Time Precise Point Positioning (PPP) technology with satellite clock and orbit corrections delivered over IP networks. The seismic recording includes an ANSS Class A, force balance accelerometer with the latest, low power, 24-bit A/D converter, producing high-resolution seismic data. The SG160-09 processor acquires and packetizes both seismic and geodetic data and transmits it to the central station using an advanced, error-correction protocol providing data integrity between the field and the processing center. The SG160-09 has been installed in three seismic stations in different geographic locations with different Trimble global reference stations coverage The hardware includes the SG160-09 system, external Zephyr Geodetic-2 GNSS antenna, both radio and high-speed Internet communication media. Both acceleration and displacement data was transmitted in real-time to the centralized Data Acquisition Centers for real-time data processing. Command/Control of the field station and real-time GNSS position correction are provided via the Pivot platform. Data from the SG160-09 system was used for seismic event characterization along with data from traditional seismic and geodetic stations

Approximation by Müntz spaces on positive intervals

KAUST Repository

Ait-Haddou, Rachid

2013-11-01

The so-called Bernstein operators were introduced by S.N. Bernstein in 1912 to give a constructive proof of Weierstrass\\' theorem. We show how to extend his result to Müntz spaces on positive intervals. © 2013 Académie des sciences.

Approximation by Müntz spaces on positive intervals

KAUST Repository

Ait-Haddou, Rachid; Mazure, Marie Laurence

2013-01-01

The so-called Bernstein operators were introduced by S.N. Bernstein in 1912 to give a constructive proof of Weierstrass' theorem. We show how to extend his result to Müntz spaces on positive intervals. © 2013 Académie des sciences.

Wavelet based comparison of high frequency oscillations in the geodetic and fluid excitation functions of polar motion

Science.gov (United States)

Kosek, W.; Popinski, W.; Niedzielski, T.

2011-10-01

It has been already shown that short period oscillations in polar motion, with periods less than 100 days, are very chaotic and are responsible for increase in short-term prediction errors of pole coordinates data. The wavelet technique enables to compare the geodetic and fluid excitation functions in the high frequency band in many different ways, e.g. by looking at the semblance function. The waveletbased semblance filtering enables determination the common signal in both geodetic and fluid excitation time series. In this paper the considered fluid excitation functions consist of the atmospheric, oceanic and land hydrology excitation functions from ECMWF atmospheric data produced by IERS Associated Product Centre Deutsches GeoForschungsZentrum, Potsdam. The geodetic excitation functions have been computed from the combined IERS pole coordinates data.

Positioning with stationary emitters in a two-dimensional space-time

International Nuclear Information System (INIS)

Coll, Bartolome; Ferrando, Joan Josep; Morales, Juan Antonio

2006-01-01

The basic elements of the relativistic positioning systems in a two-dimensional space-time have been introduced in a previous work [Phys. Rev. D 73, 084017 (2006)] where geodesic positioning systems, constituted by two geodesic emitters, have been considered in a flat space-time. Here, we want to show in what precise senses positioning systems allow to make relativistic gravimetry. For this purpose, we consider stationary positioning systems, constituted by two uniformly accelerated emitters separated by a constant distance, in two different situations: absence of gravitational field (Minkowski plane) and presence of a gravitational mass (Schwarzschild plane). The physical coordinate system constituted by the electromagnetic signals broadcasting the proper time of the emitters are the so called emission coordinates, and we show that, in such emission coordinates, the trajectories of the emitters in both situations, the absence and presence of a gravitational field, are identical. The interesting point is that, in spite of this fact, particular additional information on the system or on the user allows us not only to distinguish both space-times, but also to complete the dynamical description of emitters and user and even to measure the mass of the gravitational field. The precise information under which these dynamical and gravimetric results may be obtained is carefully pointed out

Stress coupling in the seismic cycle indicated from geodetic measurements

Science.gov (United States)

Wang, L.; Hainzl, S.; Zoeller, G.; Holschneider, M.

2012-12-01

The seismic cycle includes several phases, the interseismic, coseismic and postseismic phase. In the interseismic phase, strain gradually builds up around the overall locked fault in tens to thousands of years, while it is coseismically released in seconds. In the postseismic interval, stress relaxation lasts months to years, indicated by evident aseismic deformations which have been indicated to release comparable or even higher strain energy than the main shocks themselves. Benefiting from the development of geodetic observatory, e.g., Global Positioning System (GPS) and Interferometric Synthetic Aperture Radar (InSAR) in the last two decades, the measurements of surface deformation have been significantly improved and become valuable information for understanding the stress evolution on the large fault plane. In this study, we utilize the GPS/InSAR data to investigate the slip deficit during the interseismic phase, the coseismic slip and the early postseismic creep on the fault plane. However, it is already well-known that slip inversions based only on the surface measurements are typically non-unique and subject to large uncertainties. To reduce the ambiguity, we utilize the assumption of stress coupling between interseismic and coseismic phases, and between coseismic and postseismic phases. We use a stress constrained joint inversion in Bayesian approach (Wang et al., 2012) to invert simultaneously for (1) interseismic slip deficit and coseismic slip, and (2) coseismic slip and postseismic creep. As case studies, we analyze earthquakes occurred in well-instrumented regions such as the 2004 M6.0 Parkfield earthquake, the 2010 M8.7 earthquake and the 2011 M9.1 Tohoku-Oki earthquake. We show that the inversion with the stress-coupling constraint leads to better constrained slip distributions. Meanwhile, the results also indicate that the assumed stress coupling is reasonable and can be well reflected from the available geodetic measurements. Reference: Lifeng

Incorporating Geodetic Technologies in to Field and Campus Courses at the University of Michigan: Best Practices and Lessons Learned

Science.gov (United States)

Niemi, N. A.; Clark, M. K.

2017-12-01

For the past 6 years, the University of Michigan has implemented geodetic techniques into both summer field courses and on-campus courses. The primary means for incorporating these technologies has been a partnership with UNAVCO to introduce terrestrial laser scanning (TLS) at summer field courses, although employing Structure from Motion(SfM), ArcCollector for iPads and RTK GPS surveying have also been explored. The nature of these types of data lend themselves readily to geomorphology, environmental, and natural hazards-based projects, and we have developed field projects or labs around neotectonics (fault-scarp scanning and diffusion analysis), change detection (braided stream evolution, landslide and rock glacier motion, coastal change) and mass wasting processes (rock avalanche scanning and analysis). While we have primarily developed multi-day projects that use these tools in a field camp setting, we have also developed weekend field trip projects and traditional afternoon lab exercises associated with on-campus courses. The use of geodetic technology is generally well received by students. Reasons for this are the use of somewhat different skill sets from traditional geologic mapping problems, including research survey design, real-time data acquisition, and quantitative data analysis. Students also perceive that they are engaged in learning technology which they may use in their future employment. Challenges encountered, particularly in the field, include managing large student groups with a finite pool of equipment, rapid data processing pressures, variable student experience with analysis software and limited technical support for field-based computational resources. We will describe the positive attributes of incorporating geodetic technologies into undergraduate courses and elaborate on some best practices learned from our experiences.

Slow Earthquake Hunters: A New Citizen Science Project to Identify and Catalog Slow Slip Events in Geodetic Data

Science.gov (United States)

Bartlow, N. M.

2017-12-01

Slow Earthquake Hunters is a new citizen science project to detect, catalog, and monitor slow slip events. Slow slip events, also called "slow earthquakes", occur when faults slip too slowly to generate significant seismic radiation. They typically take between a few days and over a year to occur, and are most often found on subduction zone plate interfaces. While not dangerous in and of themselves, recent evidence suggests that monitoring slow slip events is important for earthquake hazards, as slow slip events have been known to trigger damaging "regular" earthquakes. Slow slip events, because they do not radiate seismically, are detected with a variety of methods, most commonly continuous geodetic Global Positioning System (GPS) stations. There is now a wealth of GPS data in some regions that experience slow slip events, but a reliable automated method to detect them in GPS data remains elusive. This project aims to recruit human users to view GPS time series data, with some post-processing to highlight slow slip signals, and flag slow slip events for further analysis by the scientific team. Slow Earthquake Hunters will begin with data from the Cascadia subduction zone, where geodetically detectable slow slip events with a duration of at least a few days recur at regular intervals. The project will then expand to other areas with slow slip events or other transient geodetic signals, including other subduction zones, and areas with strike-slip faults. This project has not yet rolled out to the public, and is in a beta testing phase. This presentation will show results from an initial pilot group of student participants at the University of Missouri, and solicit feedback for the future of Slow Earthquake Hunters.

Geodetic and geophysical observations in Antarctica an overview in the IPY perspective

CERN Document Server

Capra, Alessandro

2008-01-01

This book is a collection of papers on various aspects of the geodetic and geophysical investigation and observation techniques. It includes material from the Arctic and Antarctica, as well as covering work from both temporary and permanent observatories.

Research on Geometric Positioning Algorithm of License Plate in Multidimensional Parameter Space

Directory of Open Access Journals (Sweden)

Yinhua Huan

2014-05-01

Full Text Available Considering features of vehicle license plate location method which commonly used, in order to search a consistent location for reference images with license plates feature in multidimensional parameter space, a new algorithm of geometric location is proposed. Geometric location algorithm main include model training and real time search. Which not only adapt the gray-scale linearity and the gray non-linear changes, but also support changes of scale and angle. Compared with the mainstream locating software, numerical results shows under the same test conditions that the position deviation of geometric positioning algorithm is less than 0.5 pixel. Without taking into account the multidimensional parameter space, Geometric positioning algorithm position deviation is less than 1.0 pixel and angle deviation is less than 1.0 degree taking into account the multidimensional parameter space. This algorithm is robust, simple, practical and is better than the traditional method.

The State of GPS Vertical Positioning Precision : Separation of Earth Processes by Space Geodesy

CERN Document Server

2003-01-01

Observed signals in GPS data are the sum of noise and real crustal motions. Interpretation of the data depends on our ability to extract a signal of interest from the total signal. This workshop will highlight the difficulties associated with extracting a signal such as post-glacial rebound, plate tectonics or loading, from vertical geodetic data.

Geodetic contributions to IWRM-projects in middle Java, Indonesia

Science.gov (United States)

Schmitt, Günter

2010-12-01

The district of Gunung Kidul in middle Java is one of the poorest regions in Indonesia. The essential reason is the acute water scarcity in this karst region during the months of the dry season. As a consequence of the poor living conditions many people have migrated away and therefore the development of the region is stagnating. During the last few years two projects have been initiated under the theme “Integrated Water Resources Management” in order to improve the water supply situation, both funded by the German Federal Ministry of Education and Research, and realized essentially by institutes of the University of Karlsruhe. Geodetic sub-projects are integrated into both projects. Special surveying activities had been, and have still to be, carried out to realise the geometrical basis for several other sub-projects. The particular contributions are 3D cave measurements for visualisation and planning, staking out of drilling points and construction axes, the definition of a common reference system, the surveying of the water distribution network and its technical facilities, the setting up and the management of a geographical information system (GIS), as well as special measurements such as dam monitoring or controlling of a vertical drilling machine. The paper reviews these projects and describes the geodetic activities.

Deformation offshore Northern Chile monitored by a seafloor geodetic network (GeoSEA)

Science.gov (United States)

Hannemann, Katrin; Lange, Dietrich; Kopp, Heidrun; Petersen, Florian; Contreras-Reyes, Eduardo

2017-04-01

The Nazca-South American plate boundary around 21°S has last ruptured in an earthquake in 1877 and was identified as a seismic gap prior to the 2014 Iquique earthquake (Mw=8.1). The southern portion of this segment is still unbroken. The geodetic monitoring of the Chilean subduction zone is crucial to understand the deformation processes in this area. Most geodetic measurements rely on GPS and are therefore limited to onshore campaigns. In December 2015, we installed the GeoSEA (Geodetic Earthquake Observatory on the SEAfloor) array around 21°S of the Nazca-South American plate boundary with RV SONNE to extend the geodetic observations to the offshore areas. The GeoSEA array consists of autonomous acoustic seafloor transponders mounted on 4 m high tripods. These transponders are able to continuously measure the two-way travel time of acoustic signals between station pairs (baselines) and the properties of the sea water (sound speed, temperature and pressure) at each transponder. These measurements are used to retrieve the distances between the transponders and give insights into the deformation of the seafloor. At the Chilean subduction zone, we installed in total 23 transponders in 3 subarrays with interstation distances of up to 2500 m. On the middle continental slope in 2300 m water depth, an array consisting of 8 transponders measures across crustal faults seen in AUV mapping. A second array of 5 stations located on the outer rise monitors extension across normal plate-bending faults. The deepest deployment in 5000 m water depth located on the lower continental slope with 10 stations is designed to measure diffuse strain build-up. The transponders are intended to monitor the seafloor deformation for 3.5 years. In November 2016 during a cruise of RV Langseth, the first 11 months of data were successfully uploaded via an acoustic modem. Furthermore, an additional component of the network, GeoSURF, a self-steering autonomous vehicle (wave glider), was

Monitoring Coral Growth - the Dichotomy Between Underwater Photogrammetry and Geodetic Control Network

Science.gov (United States)

Neyer, F.; Nocerino, E.; Gruen, A.

2018-05-01

Creating 3-dimensional (3D) models of underwater scenes has become a common approach for monitoring coral reef changes and its structural complexity. Also in underwater archeology, 3D models are often created using underwater optical imagery. In this paper, we focus on the aspect of detecting small changes in the coral reef using a multi-temporal photogrammetric modelling approach, which requires a high quality control network. We show that the quality of a good geodetic network limits the direct change detection, i.e., without any further registration process. As the photogrammetric accuracy is expected to exceed the geodetic network accuracy by at least one order of magnitude, we suggest to do a fine registration based on a number of signalized points. This work is part of the Moorea Island Digital Ecosystem Avatar (IDEA) project that has been initiated in 2013 by a group of international researchers (https://mooreaidea.ethz.ch/).

Resolution testing and limitations of geodetic and tsunami datasets for finite fault inversions along subduction zones

Science.gov (United States)

Williamson, A.; Newman, A. V.

2017-12-01

Finite fault inversions utilizing multiple datasets have become commonplace for large earthquakes pending data availability. The mixture of geodetic datasets such as Global Navigational Satellite Systems (GNSS) and InSAR, seismic waveforms, and when applicable, tsunami waveforms from Deep-Ocean Assessment and Reporting of Tsunami (DART) gauges, provide slightly different observations that when incorporated together lead to a more robust model of fault slip distribution. The merging of different datasets is of particular importance along subduction zones where direct observations of seafloor deformation over the rupture area are extremely limited. Instead, instrumentation measures related ground motion from tens to hundreds of kilometers away. The distance from the event and dataset type can lead to a variable degree of resolution, affecting the ability to accurately model the spatial distribution of slip. This study analyzes the spatial resolution attained individually from geodetic and tsunami datasets as well as in a combined dataset. We constrain the importance of distance between estimated parameters and observed data and how that varies between land-based and open ocean datasets. Analysis focuses on accurately scaled subduction zone synthetic models as well as analysis of the relationship between slip and data in recent large subduction zone earthquakes. This study shows that seafloor deformation sensitive datasets, like open-ocean tsunami waveforms or seafloor geodetic instrumentation, can provide unique offshore resolution for understanding most large and particularly tsunamigenic megathrust earthquake activity. In most environments, we simply lack the capability to resolve static displacements using land-based geodetic observations.

Influence of bad measurements in properties of GeodeticNnetwork

Directory of Open Access Journals (Sweden)

Vincent Jakub

2008-12-01

Full Text Available In establishment of LGS (Local geodetic Net some given coordinated points from the relevant area are used, new points areestablished and the required distances and angles among the points are measured. If some measurements are defective, the netadjustment with the obtained values is depreciated, unacceptable. In the paper there is given an identification method of incorrectmeasurement results. The faulty results are eliminated in a new adjustment or the relevant defective measurements are repeated forobtaining correct values.

Relativistic space-time positioning: principles and strategies

Science.gov (United States)

Tartaglia, Angelo

2013-11-01

Starting from the description of space- time as a curved four-dimensional manifold, null Gaussian coordinates systems as appropriate for relativistic positioning will be discussed. Different approaches and strategies will be reviewed, implementing the null coordinates with both continuous and pulsating electromagnetic signals. In particular, methods based on purely local measurements of proper time intervals between pulses will be expounded and the various possible sources of uncertainty will be analyzed. As sources of pulses both artificial and natural emitters will be considered. The latter will concentrate on either radio- or X ray-emitting pulsars, discussing advantages and drawbacks. As for artificial emitters, various solutions will be presented, from satellites orbiting the Earth to broadcasting devices carried both by spacecrafts and celestial bodies of the solar system. In general the accuracy of the positioning is expected to be limited, besides the instabilities and drift of the sources, by the precision of the local clock, but in any case in long journeys systematic cumulated errors will tend to become dominant. The problem can be kept under control properly using a high level of redundancy in the procedure for the calculation of the coordinates of the receiver and by mixing a number of different and complementary strategies. Finally various possibilities for doing fundamental physics experiments by means of space-time topography techniques will shortly be presented and discussed.

Preserving the nuclear option: The AIAA position paper on space nuclear power

International Nuclear Information System (INIS)

Allen, D.M.; Bennett, G.L.; El-Genk, M.S.; Newhouse, A.R.; Rose, M.F.; Rovang, R.D.

1996-01-01

In response to published reports about the decline in funding for space nuclear power, the Board of Directors of the American Institute of Aeronautics and Astronautics (AIAA) approved a position paper in March 1995 that recommends (1) development and support of an integrated space nuclear power program by DOE, NASA and DoD; (2) Congressional support for the program; (3) advocacy of the program by government and industry leaders; and (4) continuation of cooperation between the U.S. and other countries to advance nuclear power source technology and to promote safety. This position paper has been distributed to various people having oversight of the U.S. space nuclear power program. copyright 1996 American Institute of Physics

NASA space geodesy program: Catalogue of site information

Science.gov (United States)

Bryant, M. A.; Noll, C. E.

1993-01-01

This is the first edition of the NASA Space Geodesy Program: Catalogue of Site Information. This catalogue supersedes all previous versions of the Crustal Dynamics Project: Catalogue of Site Information, last published in May 1989. This document is prepared under the direction of the Space Geodesy and Altimetry Projects Office (SGAPO), Code 920.1, Goddard Space Flight Center. SGAPO has assumed the responsibilities of the Crustal Dynamics Project, which officially ended December 31, 1991. The catalog contains information on all NASA supported sites as well as sites from cooperating international partners. This catalog is designed to provde descriptions and occupation histories of high-accuracy geodetic measuring sites employing space-related techniques. The emphasis of the catalog has been in the past, and continues to be with this edition, station information for facilities and remote locations utilizing the Satellite Laser Ranging (SLR), Lunar Laser Ranging (LLR), and Very Long Baseline Interferometry (VLBI) techniques. With the proliferation of high-quality Global Positioning System (GPS) receivers and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) transponders, many co-located at established SLR and VLBI observatories, the requirement for accurate station and localized survey information for an ever broadening base of scientists and engineers has been recognized. It is our objective to provide accurate station information to scientific groups interested in these facilities.

Azimuth selection for sea level measurements using geodetic GPS receivers

Science.gov (United States)

Wang, Xiaolei; Zhang, Qin; Zhang, Shuangcheng

2018-03-01

Based on analysis of Global Positioning System (GPS) multipath signals recorded by a geodetic GPS receiver, GPS Reflectometry (GPS-R) has demonstrated unique advantages in relation to sea level monitoring. Founded on multipath reflectometry theory, sea level changes can be measured by GPS-R through spectral analysis of recorded signal-to-noise ratio data. However, prior to estimating multipath parameters, it is necessary to define azimuth and elevation angle mask to ensure the reflecting zones are on water. Here, a method is presented to address azimuth selection, a topic currently under active development in the field of GPS-R. Data from three test sites: the Kachemak Bay GPS site PBAY in Alaska (USA), Friday Harbor GPS site SC02 in the San Juan Islands (USA), and Brest Harbor GPS site BRST in Brest (France) are analyzed. These sites are located in different multipath environments, from a rural coastal area to a busy harbor, and they experience different tidal ranges. Estimates by the GPS tide gauges at azimuths selected by the presented method are compared with measurements from physical tide gauges and acceptable correspondence found for all three sites.

GPS Users Positioning Errors during Disturbed Near-Earth Space Conditions

National Research Council Canada - National Science Library

Afraimovich, E. L; Demyanov, V. V; Tatarinov, P. V; Astafieva, E. I; Zhivetiev, I. V

2006-01-01

.... (GPS Solutions, 2003, V7, N2, 109) showed, that during geomagnetic disturbances in the near space deterioration of GNSS operation quality is appeared and, as consequence, reduction of positioning accuracy and occurrence of failures...

The University, the Market, and the Geodetic Engineer or

DEFF Research Database (Denmark)

Stubkjær, Erik

2002-01-01

In Europe, universities have existed for more than 800 years. The university is the place in society for higher learning and related research. Through the ages, the universities have enjoyed a remarkably freedom relative to religious and secular powers. In recent years, the objectives and practises...... project, which concerned the education of geodetic engineers in Slovenia. The body of the paper presents a selection of ideas that shaped the university through the centuries, with a view to balance the present interest in advancing market-directed behaviour....

Characteristics of eye-position gain field populations determine geometry of visual space

Directory of Open Access Journals (Sweden)

Sidney R Lehky

2016-01-01

Full Text Available We have previously demonstrated differences in eye-position spatial maps for anterior inferotemporal cortex (AIT in the ventral stream and lateral intraparietal cortex (LIP in the dorsal stream, based on population decoding of gaze angle modulations of neural visual responses (i.e., eye-position gain fields. Here we explore the basis of such spatial encoding differences through modeling of gain field characteristics. We created a population of model neurons, each having a different eye-position gain field. This population was used to reconstruct eye-position visual space using multidimensional scaling. As gain field shapes have never been well established experimentally, we examined different functions, including planar, sigmoidal, elliptical, hyperbolic, and mixtures of those functions. All functions successfully recovered positions, indicating weak constraints on allowable gain field shapes. We then used a genetic algorithm to modify the characteristics of model gain field populations until the recovered spatial maps closely matched those derived from monkey neurophysiological data in AIT and LIP. The primary differences found between model AIT and LIP gain fields were that AIT gain fields were more foveally dominated. That is, gain fields in AIT operated on smaller spatial scales and smaller dispersions than in LIP. Thus we show that the geometry of eye-position visual space depends on the population characteristics of gain fields, and that differences in gain field characteristics for different cortical areas may underlie differences in the representation of space.

Rapid Ice-Sheet Changes and Mechanical Coupling to Solid-Earth/Sea-Level and Space Geodetic Observation

Science.gov (United States)

Adhikari, S.; Ivins, E. R.; Larour, E. Y.

2015-12-01

Perturbations in gravitational and rotational potentials caused by climate driven mass redistribution on the earth's surface, such as ice sheet melting and terrestrial water storage, affect the spatiotemporal variability in global and regional sea level. Here we present a numerically accurate, computationally efficient, high-resolution model for sea level. Unlike contemporary models that are based on spherical-harmonic formulation, the model can operate efficiently in a flexible embedded finite-element mesh system, thus capturing the physics operating at km-scale yet capable of simulating geophysical quantities that are inherently of global scale with minimal computational cost. One obvious application is to compute evolution of sea level fingerprints and associated geodetic and astronomical observables (e.g., geoid height, gravity anomaly, solid-earth deformation, polar motion, and geocentric motion) as a companion to a numerical 3-D thermo-mechanical ice sheet simulation, thus capturing global signatures of climate driven mass redistribution. We evaluate some important time-varying signatures of GRACE inferred ice sheet mass balance and continental hydrological budget; for example, we identify dominant sources of ongoing sea-level change at the selected tide gauge stations, and explain the relative contribution of different sources to the observed polar drift. We also report our progress on ice-sheet/solid-earth/sea-level model coupling efforts toward realistic simulation of Pine Island Glacier over the past several hundred years.

Positioning Space Solar Power (SSP) as the Next Logical Step after the International Space Station (ISS)

Science.gov (United States)

Charania, A.

2002-01-01

At the end of the first decade of the 21st century, the International Space Station (ISS) will stand as a testament of the engineering capabilities of the international community. The choices for the next logical step for this community remain vast and conflicting: a Mars mission, moon colonization, Space Solar Power (SSP), etc. This examination focuses on positioning SSP as one such candidate for consideration. A marketing roadmap is presented that reveals the potential benefits of SSP to both the space community and the global populace at large. Recognizing that scientific efficiency itself has no constituency large enough to persuade entities to outlay funds for such projects, a holistic approach is taken to positioning SSP. This includes the scientific, engineering, exploratory, economic, political, and development capabilities of the system. SSP can be seen as both space exploration related and a resource project for undeveloped nations. Coupling these two non-traditional areas yields a broader constituency for the project that each one alone could generate. Space exploration is many times seen as irrelevant to the condition of the populace of the planet from which the money comes for such projects. When in this new century, billions of people on the planet still have never made a phone call or even have access to clean water, the origins of this skepticism can be understandable. An area of concern is the problem of not living up to the claims of overeager program marketers. Just as the ISS may never live up to the claims of its advocates in terms of space research, any SSP program must be careful in not promising utopian global solutions to any future energy starved world. Technically, SSP is a very difficult problem, even harder than creating the ISS, yet the promise it can hold for both space exploration and Earth development can lead to a renaissance of the relevance of space to the lives of the citizens of the world.

Precise Orbital and Geodetic Parameter Estimation using SLR Observations for ILRS AAC

Directory of Open Access Journals (Sweden)

Young-Rok Kim

2013-12-01

Full Text Available In this study, we present results of precise orbital geodetic parameter estimation using satellite laser ranging (SLR observations for the International Laser Ranging Service (ILRS associate analysis center (AAC. Using normal point observations of LAGEOS-1, LAGEOS-2, ETALON-1, and ETALON-2 in SLR consolidated laser ranging data format, the NASA/ GSFC GEODYN II and SOLVE software programs were utilized for precise orbit determination (POD and finding solutions of a terrestrial reference frame (TRF and Earth orientation parameters (EOPs. For POD, a weekly-based orbit determination strategy was employed to process SLR observations taken from 20 weeks in 2013. For solutions of TRF and EOPs, loosely constrained scheme was used to integrate POD results of four geodetic SLR satellites. The coordinates of 11 ILRS core sites were determined and daily polar motion and polar motion rates were estimated. The root mean square (RMS value of post-fit residuals was used for orbit quality assessment, and both the stability of TRF and the precision of EOPs by external comparison were analyzed for verification of our solutions. Results of post-fit residuals show that the RMS of the orbits of LAGEOS-1 and LAGEOS-2 are 1.20 and 1.12 cm, and those of ETALON-1 and ETALON-2 are 1.02 and 1.11 cm, respectively. The stability analysis of TRF shows that the mean value of 3D stability of the coordinates of 11 ILRS core sites is 7.0 mm. An external comparison, with respect to International Earth rotation and Reference systems Service (IERS 08 C04 results, shows that standard deviations of polar motion Xp and Yp are 0.754 milliarcseconds (mas and 0.576 mas, respectively. Our results of precise orbital and geodetic parameter estimation are reasonable and help advance research at ILRS AAC.

Geodetic reanalysis of annual glaciological mass balances (2001-2011) of Hintereisferner, Austria

Science.gov (United States)

Klug, Christoph; Bollmann, Erik; Galos, Stephan Peter; Nicholson, Lindsey; Prinz, Rainer; Rieg, Lorenzo; Sailer, Rudolf; Stötter, Johann; Kaser, Georg

2018-03-01

This study presents a reanalysis of the glaciologically obtained annual glacier mass balances at Hintereisferner, Ötztal Alps, Austria, for the period 2001-2011. The reanalysis is accomplished through a comparison with geodetically derived mass changes, using annual high-resolution airborne laser scanning (ALS). The grid-based adjustments for the method-inherent differences are discussed along with associated uncertainties and discrepancies of the two methods of mass balance measurements. A statistical comparison of the two datasets shows no significant difference for seven annual, as well as the cumulative, mass changes over the 10-year record. Yet, the statistical view hides significant differences in the mass balance years 2002/03 (glaciological minus geodetic records = +0.92 m w.e.), 2005/06 (+0.60 m w.e.), and 2006/07 (-0.45 m w.e.). We conclude that exceptional meteorological conditions can render the usual glaciological observational network inadequate. Furthermore, we consider that ALS data reliably reproduce the annual mass balance and can be seen as validation or calibration tools for the glaciological method.

A Community-based Partnership for a Sustainable GNSS Geodetic Network

Science.gov (United States)

Dokka, R. K.

2009-12-01

Geodetic networks offer unparalleled opportunities to monitor and understand many of the rhythms of the Earth most vital to the sustainability of modern and future societies, i.e., crustal motions, sea-level, and the weather. For crustal deformation studies, the advantage is clear. Modern measurements allow us to document not only the permanent strains incurred over a seismic cycle, for example, but also the ephemeral strains that are critical for understanding the underlying physical mechanism. To be effective for science, however, geodetic networks must be properly designed, capitalized, and maintained over sufficient time intervals to fully capture the processes in action. Unfortunately, most networks lack interoperability and lack a business plan to ensure long term sustainability. The USA, for example, lacks a unified nation-wide GNSS network that can sustain its self over the coming years, decades, and century. Current federal priorities do not yet envision such a singular network. Publicly and privately funded regional networks exist, but tend to be parochial in scope, and optimized for a special user community, e.g., surveying, crustal motions, etc. Data sharing is common, but the lack of input at the beginning limits the functionality of the system for non-primary users. Funding for private networks depend heavily on the user demand, business cycle, and regulatory requirements. Agencies funding science networks offer no guarantee of sustained support. An alternative model (GULFNet) developed in Louisiana is meeting user needs, is sustainable, and is helping engineers, surveyors, and geologists become more spatially enabled. The common denominator among all participants is the view that accurate, precise, and timely geodetic data have tangible value for all segments of society. Although operated by a university (LSU), GULFNet is a community-based partnership between public and private sectors. GULFNet simultaneously achieves scientific goals by providing

New Antarctic Gravity Anomaly Grid for Enhanced Geodetic and Geophysical Studies in Antarctica.

Science.gov (United States)

Scheinert, M; Ferraccioli, F; Schwabe, J; Bell, R; Studinger, M; Damaske, D; Jokat, W; Aleshkova, N; Jordan, T; Leitchenkov, G; Blankenship, D D; Damiani, T M; Young, D; Cochran, J R; Richter, T D

2016-01-28

Gravity surveying is challenging in Antarctica because of its hostile environment and inaccessibility. Nevertheless, many ground-based, airborne and shipborne gravity campaigns have been completed by the geophysical and geodetic communities since the 1980s. We present the first modern Antarctic-wide gravity data compilation derived from 13 million data points covering an area of 10 million km 2 , which corresponds to 73% coverage of the continent. The remove-compute-restore technique was applied for gridding, which facilitated levelling of the different gravity datasets with respect to an Earth Gravity Model derived from satellite data alone. The resulting free-air and Bouguer gravity anomaly grids of 10 km resolution are publicly available. These grids will enable new high-resolution combined Earth Gravity Models to be derived and represent a major step forward towards solving the geodetic polar data gap problem. They provide a new tool to investigate continental-scale lithospheric structure and geological evolution of Antarctica.

New Antarctic Gravity Anomaly Grid for Enhanced Geodetic and Geophysical Studies in Antarctica

Science.gov (United States)

Scheinert, M.; Ferraccioli, F.; Schwabe, J.; Bell, R.; Studinger, M.; Damaske, D.; Jokat, W.; Aleshkova, N.; Jordan, T.; Leitchenkov, G.; Blankenship, D. D.; Damiani, T. M.; Young, D.; Cochran, J. R.; Richter, T. D.

2018-01-01

Gravity surveying is challenging in Antarctica because of its hostile environment and inaccessibility. Nevertheless, many ground-based, airborne and shipborne gravity campaigns have been completed by the geophysical and geodetic communities since the 1980s. We present the first modern Antarctic-wide gravity data compilation derived from 13 million data points covering an area of 10 million km2, which corresponds to 73% coverage of the continent. The remove-compute-restore technique was applied for gridding, which facilitated levelling of the different gravity datasets with respect to an Earth Gravity Model derived from satellite data alone. The resulting free-air and Bouguer gravity anomaly grids of 10 km resolution are publicly available. These grids will enable new high-resolution combined Earth Gravity Models to be derived and represent a major step forward towards solving the geodetic polar data gap problem. They provide a new tool to investigate continental-scale lithospheric structure and geological evolution of Antarctica. PMID:29326484

Spaces of positive and negative frequency solutions of field equations in curved space--times. I. The Klein--Gordon equation in stationary space--times

International Nuclear Information System (INIS)

Moreno, C.

1977-01-01

In stationary space--times V/sub n/ x R with compact space-section manifold without boundary V/sub n/, the Klein--Gordon equation is solved by the one-parameter group of unitary operators generated by the energy operator i -1 T -1 in the Sobolev spaces H/sup l/(V/sub n/) x H/sup l/(V/sub n/). The canonical symplectic and complex structures of the associated dynamical system are calculated. The existence and the uniqueness of the Lichnerowicz kernel are established. The Hilbert spaces of positive and negative frequency-part solutions defined by means of this kernel are constructed

Introducing a New Software for Geodetic Analysis

Science.gov (United States)

Hjelle, Geir Arne; Dähnn, Michael; Fausk, Ingrid; Kirkvik, Ann-Silje; Mysen, Eirik

2017-04-01

At the Norwegian Mapping Authority, we are currently developing Where, a new software for geodetic analysis. Where is built on our experiences with the Geosat software, and will be able to analyse and combine data from VLBI, SLR, GNSS and DORIS. The software is mainly written in Python which has proved very fruitful. The code is quick to write and the architecture is easily extendable and maintainable, while at the same time taking advantage of well-tested code like the SOFA and IERS libraries. This presentation will show some of the current capabilities of Where, including benchmarks against other software packages, and outline our plans for further progress. In addition we will report on some investigations we have done experimenting with alternative weighting strategies for VLBI.

Unification of Quantum and Gravity by Non Classical Information Entropy Space

Directory of Open Access Journals (Sweden)

Davide Fiscaletti

2013-09-01

Full Text Available A quantum entropy space is suggested as the fundamental arena describing the quantum effects. In the quantum regime the entropy is expressed as the superposition of many different Boltzmann entropies that span the space of the entropies before any measure. When a measure is performed the quantum entropy collapses to one component. A suggestive reading of the relational interpretation of quantum mechanics and of Bohm’s quantum potential in terms of the quantum entropy are provided. The space associated with the quantum entropy determines a distortion in the classical space of position, which appears as a Weyl-like gauge potential connected with Fisher information. This Weyl-like gauge potential produces a deformation of the moments which changes the classical action in such a way that Bohm’s quantum potential emerges as consequence of the non classical definition of entropy, in a non-Euclidean information space under the constraint of a minimum condition of Fisher information (Fisher Bohm- entropy. Finally, the possible quantum relativistic extensions of the theory and the connections with the problem of quantum gravity are investigated. The non classical thermodynamic approach to quantum phenomena changes the geometry of the particle phase space. In the light of the representation of gravity in ordinary phase space by torsion in the flat space (Teleparallel gravity, the change of geometry in the phase space introduces quantum phenomena in a natural way. This gives a new force to F. Shojai’s and A. Shojai’s theory where the geometry of space-time is highly coupled with a quantum potential whose origin is not the Schrödinger equation but the non classical entropy of a system of many particles that together change the geometry of the phase space of the positions (entanglement. In this way the non classical thermodynamic changes the classical geodetic as a consequence of the quantum phenomena and quantum and gravity are unified. Quantum

Draft position paper on knowledge management in space activities

Science.gov (United States)

Holm, Jeanne; Moura, Denis

2003-01-01

As other fields of industry, space activities are facing the challenge of Knowledge Management and the International Academy of Astronautics decided to settle in 2002 a Study Group to analyse the problem and issue general guidelines. This communication presents the draft position paper of this group in view to be discussed during the 2003 IAF Congress.

Positive definite functions and dual pairs of locally convex spaces

Directory of Open Access Journals (Sweden)

Daniel Alpay

2018-01-01

Full Text Available Using pairs of locally convex topological vector spaces in duality and topologies defined by directed families of sets bounded with respect to the duality, we prove general factorization theorems and general dilation theorems for operator-valued positive definite functions.

Automated and dynamic scheduling for geodetic VLBI - A simulation study for AuScope and global networks

Science.gov (United States)

Iles, E. J.; McCallum, L.; Lovell, J. E. J.; McCallum, J. N.

2018-02-01

As we move into the next era of geodetic VLBI, the scheduling process is one focus for improvement in terms of increased flexibility and the ability to react with changing conditions. A range of simulations were conducted to ascertain the impact of scheduling on geodetic results such as Earth Orientation Parameters (EOPs) and station coordinates. The potential capabilities of new automated scheduling modes were also simulated, using the so-called 'dynamic scheduling' technique. The primary aim was to improve efficiency for both cost and time without losing geodetic precision, particularly to maximise the uses of the Australian AuScope VLBI array. We show that short breaks in observation will not significantly degrade the results of a typical 24 h experiment, whereas simply shortening observing time degrades precision exponentially. We also confirm the new automated, dynamic scheduling mode is capable of producing the same standard of result as a traditional schedule, with close to real-time flexibility. Further, it is possible to use the dynamic scheduler to augment the 3 station Australian AuScope array and thereby attain EOPs of the current global precision with only intermittent contribution from 2 additional stations. We thus confirm automated, dynamic scheduling bears great potential for flexibility and automation in line with aims for future continuous VLBI operations.

Position space analysis of the AdS (in)stability problem

Science.gov (United States)

Dimitrakopoulos, Fotios V.; Freivogel, Ben; Lippert, Matthew; Yang, I.-Sheng

2015-08-01

We investigate whether arbitrarily small perturbations in global AdS space are generically unstable and collapse into black holes on the time scale set by gravitational interactions. We argue that current evidence, combined with our analysis, strongly suggests that a set of nonzero measure in the space of initial conditions does not collapse on this time scale. We perform an analysis in position space to study this puzzle, and our formalism allows us to directly study the vanishing-amplitude limit. We show that gravitational self-interaction leads to tidal deformations which are equally likely to focus or defocus energy, and we sketch the phase diagram accordingly. We also clarify the connection between gravitational evolution in global AdS and holographic thermalization.

Position space analysis of the AdS (in)stability problem

Energy Technology Data Exchange (ETDEWEB)

Dimitrakopoulos, Fotios V.; Freivogel, Ben; Lippert, Matthew; Yang, I-Sheng [ITFA and GRAPPA, Universiteit van Amsterdam,Science Park 904, 1090 GL Amsterdam (Netherlands)

2015-08-17

We investigate whether arbitrarily small perturbations in global AdS space are generically unstable and collapse into black holes on the time scale set by gravitational interactions. We argue that current evidence, combined with our analysis, strongly suggests that a set of nonzero measure in the space of initial conditions does not collapse on this time scale. We perform an analysis in position space to study this puzzle, and our formalism allows us to directly study the vanishing-amplitude limit. We show that gravitational self-interaction leads to tidal deformations which are equally likely to focus or defocus energy, and we sketch the phase diagram accordingly. We also clarify the connection between gravitational evolution in global AdS and holographic thermalization.

The Importance of Geodetically Controlled Data Sets: THEMIS Controlled Mosaics of Mars, a Case Study

Science.gov (United States)

Fergason, R. L.; Weller, L.

2018-04-01

Accurate image registration is necessary to answer questions that are key to addressing fundamental questions about our universe. To provide such a foundational product for Mars, we have geodetically controlled and mosaicked THEMIS IR images.

Cooperative research in space geodesy and crustal dynamics

Science.gov (United States)

1994-01-01

This research grant, which covered the period of July 1991 to August 1994, was concerned with a variety of topics within the geodesy and crustal dynamics fields. The specific topics of this grant included satellite tracking and gravity field determinations and crustal dynamics (this concentrated of space geodetic site stability for VLBI sites). Summaries of the specific research projects are included along with a list of publications and presentations supported by this research grant.

Gravity Probe B: final results of a space experiment to test general relativity.

Science.gov (United States)

Everitt, C W F; DeBra, D B; Parkinson, B W; Turneaure, J P; Conklin, J W; Heifetz, M I; Keiser, G M; Silbergleit, A S; Holmes, T; Kolodziejczak, J; Al-Meshari, M; Mester, J C; Muhlfelder, B; Solomonik, V G; Stahl, K; Worden, P W; Bencze, W; Buchman, S; Clarke, B; Al-Jadaan, A; Al-Jibreen, H; Li, J; Lipa, J A; Lockhart, J M; Al-Suwaidan, B; Taber, M; Wang, S

2011-06-03

Gravity Probe B, launched 20 April 2004, is a space experiment testing two fundamental predictions of Einstein's theory of general relativity (GR), the geodetic and frame-dragging effects, by means of cryogenic gyroscopes in Earth orbit. Data collection started 28 August 2004 and ended 14 August 2005. Analysis of the data from all four gyroscopes results in a geodetic drift rate of -6601.8±18.3  mas/yr and a frame-dragging drift rate of -37.2±7.2  mas/yr, to be compared with the GR predictions of -6606.1  mas/yr and -39.2  mas/yr, respectively ("mas" is milliarcsecond; 1  mas=4.848×10(-9)  rad).

Exploring deformation scenarios in Timanfaya volcanic area (Lanzarote, Canary Islands) from GNSS and ground based geodetic observations

Science.gov (United States)

Riccardi, U.; Arnoso, J.; Benavent, M.; Vélez, E.; Tammaro, U.; Montesinos, F. G.

2018-05-01

We report on a detailed geodetic continuous monitoring in Timanfaya volcanic area (TVA), where the most intense geothermal anomalies of Lanzarote Island are located. We analyze about three years of GNSS data collected on a small network of five permanent stations, one of which at TVA, deployed on the island, and nearly 20 years of tiltmeter and strainmeter records acquired at Los Camelleros site settled in the facilities of the Geodynamics Laboratory of Lanzarote within TVA. This study is intended to contribute to understanding the active tectonics on Lanzarote Island and its origin, mainly in TVA. After characterizing and filtering out the seasonal periodicities related to "non-tectonic" sources from the geodetic records, a tentative ground deformation field is reconstructed through the analysis of both tilt, strain records and the time evolution of the baselines ranging the GNSS stations. The joint interpretation of the collected geodetic data show that the area of the strongest geothermal anomaly in TVA is currently undergoing a SE trending relative displacement at a rate of about 3 mm/year. This area even experiences a significant subsidence with a maximum rate of about 6 mm/year. Moreover, we examine the possible relation between the observed deformations and atmospheric effects by modelling the response functions of temperature and rain recorded in the laboratory. Finally, from the retrieval of the deformation patterns and the joint analysis of geodetic and environmental observations, we propose a qualitative model of the interplaying role between the hydrological systems and the geothermal anomalies. Namely, we explain the detected time correlation between rainfall and ground deformation because of the enhancement of the thermal transfer from the underground heat source driven by the infiltration of meteoric water.

76 FR 65540 - National Space-Based Positioning, Navigation, and Timing (PNT) Advisory Board; Meeting

Science.gov (United States)

2011-10-21

.... L. 92-463, as amended), and the President's 2004 U.S. Space-Based Positioning, Navigation, and...-Based Positioning, Navigation and Timing Policy and Global Positioning System (GPS) modernization. Explore opportunities for enhancing the interoperability of GPS with other emerging international Global...

Retroreflector field tracker. [noncontact optical position sensor for space application

Science.gov (United States)

Wargocki, F. E.; Ray, A. J.; Hall, G. E.

1984-01-01

An electrooptical position-measuring instrument, the Retroreflector Field Tracker or RFT, is described. It is part of the Dynamic Augmentation Experiment - a part of the payload of Space Shuttle flight 41-D in Summer 1984. The tracker measures and outputs the position of 23 reflective targets placed on a 32-m solar array to provide data for determination of the dynamics of the lightweight structure. The sensor uses a 256 x 256 pixel CID detector; the processor electronics include three Z-80 microprocessors. A pulsed laser diode illuminator is used.

POSITIVE SOLUTIONS TO SEMI-LINEAR SECOND-ORDER ORDINARY DIFFERENTIAL EQUATIONS IN BANACH SPACE

Institute of Scientific and Technical Information of China (English)

无

2008-01-01

In this paper,we study the existence of positive periodic solution to some second- order semi-linear differential equation in Banach space.By the fixed point index theory, we prove that the semi-linear differential equation has two positive periodic solutions.

A Comparative Study of the Applied Methods for Estimating Deflection of the Vertical in Terrestrial Geodetic Measurements

Directory of Open Access Journals (Sweden)

Luca Vittuari

2016-04-01

Full Text Available This paper compares three different methods capable of estimating the deflection of the vertical (DoV: one is based on the joint use of high precision spirit leveling and Global Navigation Satellite Systems (GNSS, a second uses astro-geodetic measurements and the third gravimetric geoid models. The working data sets refer to the geodetic International Terrestrial Reference Frame (ITRF co-location sites of Medicina (Northern, Italy and Noto (Sicily, these latter being excellent test beds for our investigations. The measurements were planned and realized to estimate the DoV with a level of precision comparable to the angular accuracy achievable in high precision network measured by modern high-end total stations. The three methods are in excellent agreement, with an operational supremacy of the astro-geodetic method, being faster and more precise than the others. The method that combines leveling and GNSS has slightly larger standard deviations; although well within the 1 arcsec level, which was assumed as threshold. Finally, the geoid model based method, whose 2.5 arcsec standard deviations exceed this threshold, is also statistically consistent with the others and should be used to determine the DoV components where local ad hoc measurements are lacking.

Clinical Positioning Space

DEFF Research Database (Denmark)

Williams, Lars Peter Hedegaard; Christensen, Mette Krogh; Rytter, Carsten

2014-01-01

In this article, we present a case study of residents’ clinical experiences and communication in outpatient oncology consultations. We apply positioning theory, a dynamic alternative to role theory, to investigate how oncology residents and patients situate themselves as persons with rights...... and duties. Drawing from seven qualitative interviews and six days of observation, we investigate the residents’ social positioning and their conversations with patients or supervisors. Our focus is on how (a) relational shifts in authority depend on each situation and its participants; (b) storylines...... establish acts and positions and narratively frame what participants can expect from a medical consultation viewed as a social episode; and (c) the positioning of rights and duties can lead to misunderstandings and frustrations. We conclude that residents and patients locate themselves in outpatient...

Infrared Sensor System for Mobile-Robot Positioning in Intelligent Spaces

Directory of Open Access Journals (Sweden)

Luis Pallarés Puerto

2011-05-01

Full Text Available The aim of this work was to position a Mobile Robot in an Intelligent Space, and this paper presents a sensorial system for measuring differential phase-shifts in a sinusoidally modulated infrared signal transmitted from the robot. Differential distances were obtained from these phase-shifts, and the position of the robot was estimated by hyperbolic trilateration. Due to the extremely severe trade-off between SNR, angle (coverage and real-time response, a very accurate design and device selection was required to achieve good precision with wide coverage and acceptable robot speed. An I/Q demodulator was used to measure phases with one-stage synchronous demodulation to DC. A complete set of results from real measurements, both for distance and position estimations, is provided to demonstrate the validity of the system proposed, comparing it with other similar indoor positioning systems.

Geodetic Measurements and Mechanical Models of Cyclic Deformation at Okmok Volcano, Alaska

Science.gov (United States)

Feigl, K.; Masterlark, T.; Lu, Z.; Ohlendorf, S. J.; Thurber, C. H.; Sigmundsson, F.

2009-12-01

The 1997 and 2008 eruptions of Okmok volcano, Alaska, provide a rare opportunity for conducting a rheological experiment to unravel the complex processes associated with magma migration, storage, and eruption in an active volcano. In this experiment, the magma flux during the eruption provides the “impulse” and the subsequent, transient deformation, the “response”. By simulating the impulse, measuring the response, and interpreting the constitutive relations between the two, one can infer the rheology. Okmok is an excellent natural laboratory for such an experiment because a complete cycle of deformation has been monitored using geodetic and seismic means, including: (a) geodetic time series from Interferometric Synthetic Aperture Radar (InSAR) and the Global Positioning System (GPS), (b) earthquake locations; and (c) seismic tomography. We are developing quantitative models using the Finite Element Method (FEM) to simulate the timing and location of the observed seismicity and deformation by accounting for: (a) the geometry and loading of the magma chamber and lava flow, (b) the spatial distribution of material properties; and (c) the constitutive (rheological) relations between stress and strain. Here, we test the hypothesis that the deformation following the 1997 eruption did not reach a steady state before the eruption in 2008. To do so, we iteratively confront the FEM models with the InSAR measurements using the General Inversion of Phase Technique (GIPhT). This approach models the InSAR phase data directly, without unwrapping, as developed, validated, and applied by Feigl and Thurber [Geophys. J. Int., 2009]. By minimizing a cost function that quantifies the misfit between observed and modeled values in terms of “wrapped” phase (with values ranging from -1/2 to +1/2 cycles), GIPhT can estimate parameters in a geophysical model. By avoiding the pitfalls of phase-unwrapping approaches, GIPhT allows the analysis, interpretation and modeling of more

Crustal Deformation across the Jericho Valley Section of the Dead Sea Fault as Resolved by Detailed Field and Geodetic Observations

Science.gov (United States)

Hamiel, Yariv; Piatibratova, Oksana; Mizrahi, Yaakov; Nahmias, Yoav; Sagy, Amir

2018-04-01

Detailed field and geodetic observations of crustal deformation across the Jericho Fault section of the Dead Sea Fault are presented. New field observations reveal several slip episodes that rupture the surface, consist with strike slip and extensional deformation along a fault zone width of about 200 m. Using dense Global Positioning System measurements, we obtain the velocities of new stations across the fault. We find that this section is locked for strike-slip motion with a locking depth of 16.6 ± 7.8 km and a slip rate of 4.8 ± 0.7 mm/year. The Global Positioning System measurements also indicate asymmetrical extension at shallow depths of the Jericho Fault section, between 0.3 and 3 km. Finally, our results suggest the vast majority of the sinistral slip along the Dead Sea Fault in southern Jorden Valley is accommodated by the Jericho Fault section.

ALGORITHMS VARIANTS OF ELABORATION OF THE PRECISE GNSS NETWORK ESTABLISHED FOR GEODETIC SERVICE OF BUILDING OF THE MINING FACILITY

Directory of Open Access Journals (Sweden)

Ryszard MIELIMĄKA

2014-10-01

Full Text Available The article presents the problem of the usage of post‐processing services of the ASG‐EUPOS system on the example of GNSS network established for geodetic service of building of the inclined drift, to make coal deposit accessible, and also building associated objects. For the purpose of geodetic service of construction realization network was established outside the planned objects. The network consists of six new ground points and four control points belonging to ASG‐EUPOS network. Simultaneous, static measurements of the network were performed in three‐hour observation session, using multi‐frequency and multi‐system satellite receivers – Trimble R8. The paper presents three variants of post‐processing of the observation results. Calculations were performed using POZGEO‐D service and geodetic software package GEONET. The results of the calculation process revealed, that homogeneous vector networks should be adjusted on the ellipsoid or in the geocentric system. Model of adjustment of the vector network on the plane adopted in the GEONET software package should not be applied for elaboration of this type of network (long reference vectors more than 50km.

Cansiglio Karst Plateau: 10 Years of Geodetic-Hydrological Observations in Seismically Active Northeast Italy

Science.gov (United States)

Grillo, Barbara; Braitenberg, Carla; Nagy, Ildikó; Devoti, Roberto; Zuliani, David; Fabris, Paolo

2018-04-01

Ten years' geodetic observations (2006-2016) in a natural cave of the Cansiglio Plateau (Bus de la Genziana), a limestone karstic area in northeastern Italy, are discussed. The area is of medium-high seismic risk: a strong earthquake in 1936 below the plateau (M m = 6.2) and the 1976 disastrous Friuli earthquake (M m = 6.5) are recent events. At the foothills of the karstic massif, three springs emerge, with average flow from 5 to 10 m3/s, and which are the sources of a river. The tiltmeter station is set in a natural cavity that is part of a karstic system. From March 2013, a multiparametric logger (temperature, stage, electrical conductivity) was installed in the siphon at the bottom of the cave to discover the underground hydrodynamics. The tilt records include signals induced by hydrologic and tectonic effects. The tiltmeter signals have a clear correlation to the rainfall, the discharge series of the river and the data recorded by multiparametric loggers. Additionally, the data of a permanent GPS station located on the southern slopes of the Cansiglio Massif (CANV) show also a clear correspondence with the river level. The fast water infiltration into the epikarst, closely related to daily rainfall, is distinguished in the tilt records from the characteristic time evolution of the karstic springs, which have an impulsive level increase with successive exponential decay. It demonstrates the usefulness of geodetic measurements to reveal the hydrological response of the karst. One outcome of the work is that the tiltmeters can be used as proxies for the presence of flow channels and the pressure that builds up due to the water flow. With 10 years of data, a new multidisciplinary frontier was opened between the geodetic studies and the karstic hydrogeology to obtain a more complete geologic description of the karst plateau.

Application of Geodetic VLBI Data to Obtaining Long-Term Light Curves for Astrophysics

Science.gov (United States)

Kijima, Masachika

2010-01-01

The long-term light curve is important to research on binary black holes and disk instability in AGNs. The light curves have been drawn mainly using single dish data provided by the University of Michigan Radio Observatory and the Metsahovi Radio Observatory. Hence, thus far, we have to research on limited sources. I attempt to draw light curves using VLBI data for those sources that have not been monitored by any observatories with single dish. I developed software, analyzed all geodetic VLBI data available at the IVS Data Centers, and drew the light curves at 8 GHz. In this report, I show the tentative results for two AGNs. I compared two light curves of 4C39.25, which were drawn based on single dish data and on VLBI data. I confirmed that the two light curves were consistent. Furthermore, I succeeded in drawing the light curve of 0454-234 with VLBI data, which has not been monitored by any observatory with single dish. In this report, I suggest that the geodetic VLBI archive data is useful to obtain the long-term light curves at radio bands for astrophysics.

Development of Magneto-Resistive Angular Position Sensors for Space Applications

Science.gov (United States)

Hahn, Robert; Langendorf, Sven; Seifart, Klaus; Slatter, Rolf; Olberts, Bastian; Romera, Fernando

2015-09-01

Magnetic microsystems in the form of magneto- resistive (MR) sensors are firmly established in automobiles and industrial applications. They measure path, angle, electrical current, or magnetic fields. MR technology opens up new sensor possibilities in space applications and can be an enabling technology for optimal performance, high robustness and long lifetime at reasonable costs. In a recent assessment study performed by HTS GmbH and Sensitec GmbH under ESA Contract a market survey has confirmed that space industry has a very high interest in novel, contactless position sensors based on MR technology. Now, a detailed development stage is pursued, to advance the sensor design up to Engineering Qualification Model (EQM) level and to perform qualification testing for a representative pilot space application.The paper briefly reviews the basics of magneto- resistive effects and possible sensor applications and describes the key benefits of MR angular sensors with reference to currently operational industrial and space applications. The results of the assessment study are presented and potential applications and uses of contactless magneto-resistive angular sensors for spacecraft are identified. The baseline mechanical and electrical sensor design will be discussed. An outlook on the EQM development and qualification tests is provided.

Modeling and Analysis of Integrated Bathymetric and Geodetic Data for Inventory Surveys of Mining Water Reservoirs

Science.gov (United States)

Ochałek, Agnieszka; Lipecki, Tomasz; Jaśkowski, Wojciech; Jabłoński, Mateusz

2018-03-01

The significant part of the hydrography is bathymetry, which is the empirical part of it. Bathymetry is the study of underwater depth of waterways and reservoirs, and graphic presentation of measured data in form of bathymetric maps, cross-sections and three-dimensional bottom models. The bathymetric measurements are based on using Global Positioning System and devices for hydrographic measurements - an echo sounder and a side sonar scanner. In this research authors focused on introducing the case of obtaining and processing the bathymetrical data, building numerical bottom models of two post-mining reclaimed water reservoirs: Dwudniaki Lake in Wierzchosławice and flooded quarry in Zabierzów. The report includes also analysing data from still operating mining water reservoirs located in Poland to depict how bathymetry can be used in mining industry. The significant issue is an integration of bathymetrical data and geodetic data from tachymetry, terrestrial laser scanning measurements.

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

Science.gov (United States)

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.

Slip deficit on the san andreas fault at parkfield, california, as revealed by inversion of geodetic data.

Science.gov (United States)

Segall, P; Harris, R

1986-09-26

A network of geodetic lines spanning the San Andreas fault near the rupture zone of the 1966 Parkfield, California, earthquake (magnitude M = 6) has been repeatedly surveyed since 1959. In the study reported here the average rates of line-length change since 1966 were inverted to determine the distribution of interseismic slip rate on the fault. These results indicate that the Parkfield rupture surface has not slipped significantly since 1966. Comparison of the geodetically determined seismic moment of the 1966 earthquake with the interseismic slip-deficit rate suggests that the strain released by the latest shock will most likely be restored between 1984 and 1989, although this may not occur until 1995. These results lend independent support to the earlier forecast of an M = 6 earthquake near Parkfield within 5 years of 1988.

Intensity position modulation for free-space laser communication system

Science.gov (United States)

Jangjoo, Alireza; Faghihi, F.

2004-12-01

In this research a novel modulation technique for free-space laser communication system called Intensity Position Modulation (IPM) is carried out. According to TEM00 mode of a laser beam and by linear fitting on the Gaussian function as an approximation, the variation of linear part on the reverse biased pn photodiode produced alternating currents which contain the information. Here, no characteristic property of the beam as intensity or frequency is changed and only the beam position moves laterally. We demonstrated that in this method no bandwidth is required, so it is possible to reduce the background radiation noise by narrowband filtering of the carrier. The fidelity of the analog voice communication system which is made upon the IPM is satisfactory and we are able to transmit the audio signals up to 1Km.

Evaluation of a New Prototype Geodetic Astrolabe for Measuring Deflections of the Vertical

Science.gov (United States)

Slater, J. A.; Thompson, N.; Angell, L. E.; Belenkii, M. S.; Bruns, D. G.; Johnson, D. O.

2009-12-01

plate model is fitted to the topocentric coordinates of the stars, and then used to solve for the astronomical latitude and longitude of the vertical reference point on the CCD. The average of 100-150 individual image solutions (10-15 minutes) defines the astronomical position for the observation session. In order to remove an azimuthal orientation bias, the astrolabe is rotated 180°, a new observation session solution is produced for that orientation and then averaged with the first solution to get the final astronomical position of the site. By combining these coordinates with GPS-derived geodetic latitude and longitude, one obtains the DoV. Initial testing of the prototype at a known astronomic position has been completed. The tests evaluated the session-to-session and day-to-day repeatability of the solutions, the number of observations required for a solution, the accuracy with respect to the known position, and the operational robustness of the hardware and software. Based on the field tests, Trex will make improvements to the prototype hardware and software and then produce operational units for use by NGA.

Extended space expectation values of position related operators for hydrogen-like quantum system evolutions

International Nuclear Information System (INIS)

Kalay, Berfin; Demiralp, Metin

2014-01-01

The expectation value definitions over an extended space from the considered Hilbert space of the system under consideration is given in another paper of the second author in this symposium. There, in that paper, the conceptuality rather than specification is emphasized on. This work uses that conceptuality to investigate the time evolutions of the position related operators' expectation values not in its standard meaning but rather in a new version of the definition over not the original Hilbert space but in the space obtained by extensions via introducing the images of the given initial wave packet under the positive integer powers of the system Hamiltonian. These images may not be residing in the same space of the initial wave packet when certain singularities appear in the structure of the system Hamiltonian. This may break down the existence of the integrals in the definitions of the expectation values. The cure is the use of basis functions in the abovementioned extended space and the sandwiching of the target operator whose expectation value is under questioning by an appropriately chosen operator guaranteeing the existence of the relevant integrals. Work specifically focuses on the hydrogen-like quantum systems whose Hamiltonians contain a polar singularity at the origin

Global geodetic observing system meeting the requirements of a global society on a changing planet in 2020

CERN Document Server

Plag, Hans-Peter

2009-01-01

Geodesy plays a key role in geodynamics, geohazards, the global water cycle, global change, atmosphere and ocean dynamics. This book covers geodesy's contribution to science and society and identifies user needs regarding geodetic observations and products.

Binocular Vision-Based Position and Pose of Hand Detection and Tracking in Space

Science.gov (United States)

Jun, Chen; Wenjun, Hou; Qing, Sheng

After the study of image segmentation, CamShift target tracking algorithm and stereo vision model of space, an improved algorithm based of Frames Difference and a new space point positioning model were proposed, a binocular visual motion tracking system was constructed to verify the improved algorithm and the new model. The problem of the spatial location and pose of the hand detection and tracking have been solved.

Sustaining Air Force Space Systems: A Model for the Global Positioning System

National Research Council Canada - National Science Library

Snyder, Don; Mills, Patrick; Comanor, Katherine; Roll, Jr, Charles R

2007-01-01

... and sustainment affect the performance of space systems. In this monograph, we develop a pilot framework for analyzing these and related questions in the ground segment of the Global Positioning System and recommend steps for implementing this framework...

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

Directory of Open Access Journals (Sweden)

Slavomír Labant

2011-12-01

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

A new system to quantify uncertainties in LEO satellite position determination due to space weather events

Data.gov (United States)

National Aeronautics and Space Administration — We propose to develop a new system for quantitative assessment of uncertainties in LEO satellite position caused by storm time changes in space environmental...

Modeling and Analysis of Integrated Bathymetric and Geodetic Data for Inventory Surveys of Mining Water Reservoirs

Directory of Open Access Journals (Sweden)

Ochałek Agnieszka

2018-01-01

Full Text Available The significant part of the hydrography is bathymetry, which is the empirical part of it. Bathymetry is the study of underwater depth of waterways and reservoirs, and graphic presentation of measured data in form of bathymetric maps, cross-sections and three-dimensional bottom models. The bathymetric measurements are based on using Global Positioning System and devices for hydrographic measurements – an echo sounder and a side sonar scanner. In this research authors focused on introducing the case of obtaining and processing the bathymetrical data, building numerical bottom models of two post-mining reclaimed water reservoirs: Dwudniaki Lake in Wierzchosławice and flooded quarry in Zabierzów. The report includes also analysing data from still operating mining water reservoirs located in Poland to depict how bathymetry can be used in mining industry. The significant issue is an integration of bathymetrical data and geodetic data from tachymetry, terrestrial laser scanning measurements.

Covariant loops and strings in a positive definite Hilbert space

International Nuclear Information System (INIS)

Rohrlich, F.

1977-01-01

Relativistic loops and strings are defined in the conventional way as solutions of a one-dimensional wave equation with certain boundary conditions and satisfying the orthogonal gauge conditions. Conventional pseudo-Cartesian co-ordinates (rather than null-plane co-ordinates) are used. The creation and annihilation operator four-vector αsub(μ)sup(+) and αsub(m) are required to be spacelike (orthogonal to the total momentum Psup(μ), so that the resulting Fock space is positive definite. This requirements is shown to be mathematically consistent with Poincare' invariance and to impose no additional physical constraints on the system. It can be implemented in a canonical realization of the Poincare' algebra as a condition on a state vectors, or in a noncanonical realization as an operator equation, as is done here. The space is further restricted by the Virasoro conditions to a physical subspace PHI which is of course also positive definite. In this way there arises no critical-dimension problem and Poincare' invariance holds also in 3+1 dimensions. The energy and spin spectra are the same as usual, leading to linear Regge trajectories, except that there are no tachyons and no zero mass states. The leading Regge trajectory has negative intercept

Feasibility of Construction of the Continuously Operating Geodetic GPS Network of Sinaloa, Mexico

Science.gov (United States)

Vazquez, G. E.; Jacobo, C.

2011-12-01

This research is based on the study and analysis of feasibility for the construction of the geodetic network for GPS continuous operation for Sinaloa, hereafter called (RGOCSIN). A GPS network of continuous operation is defined as that materialized structure physically through permanent monuments where measurements to the systems of Global Positioning (GPS) is performed continuously throughout a region. The GPS measurements in this network are measurements of accuracy according to international standards to define its coordinates, thus constituting the basic structure of geodetic referencing for a country. In this context is that in the near future the RGOCSIN constitutes a system state only accurate and reliable georeferencing in real-time (continuous and permanent operation) and will be used for different purposes; i.e., in addition to being fundamental basis for any lifting topographic or geodetic survey, and other areas such as: (1) Different construction processes (control and monitoring of engineering works); (2) Studies of deformation of the Earth's crust (before and after a seismic event); (3) GPS meteorology (weather forecasting); (4) Demarcation projects (natural and political); (5) Establishment of bases to generate mapping (necessary for the economic and social development of the state); (6) Precision agriculture (optimization of economic resources to the various crops); (7) Geographic information systems (Organization and planning activities associated with the design and construction of public services); (8) Urban growth (possible settlements in the appropriate form and taking care of the environmental aspect), among others. However there are criteria and regulations according to the INEGI (Instituto Nacional de Estadística y Geografía, http://www.inegi.org.mx/) that must be met; even for this stage of feasibility of construction that sees this project as a first phase. The fundamental criterion to be taken into account according to INEGI is a

Positivity-preserving space-time CE/SE scheme for high speed flows

KAUST Repository

Shen, Hua

2017-03-02

We develop a space-time conservation element and solution element (CE/SE) scheme using a simple slope limiter to preserve the positivity of the density and pressure in computations of inviscid and viscous high-speed flows. In general, the limiter works with all existing CE/SE schemes. Here, we test the limiter on a central Courant number insensitive (CNI) CE/SE scheme implemented on hybrid unstructured meshes. Numerical examples show that the proposed limiter preserves the positivity of the density and pressure without disrupting the conservation law; it also improves robustness without losing accuracy in solving high-speed flows.

Positivity-preserving space-time CE/SE scheme for high speed flows

KAUST Repository

Shen, Hua; Parsani, Matteo

2017-01-01

We develop a space-time conservation element and solution element (CE/SE) scheme using a simple slope limiter to preserve the positivity of the density and pressure in computations of inviscid and viscous high-speed flows. In general, the limiter works with all existing CE/SE schemes. Here, we test the limiter on a central Courant number insensitive (CNI) CE/SE scheme implemented on hybrid unstructured meshes. Numerical examples show that the proposed limiter preserves the positivity of the density and pressure without disrupting the conservation law; it also improves robustness without losing accuracy in solving high-speed flows.

A few properties of a certain class of degenerate space-times

International Nuclear Information System (INIS)

Kowalczynski, J.K.; Plebanski, J.F.

1977-01-01

The properties are studied of a class of space-times determined by assuming the shape of the metric form ds 2 including disposable coordinate functions. It has been found that this class includes degenerate space-times with geodetic, null, shear-free congruence with nonvanishing expansion. The theorem has been proved that this class of solutions of the Einstein equations can easily be expanded to solutions of Einstein-Maxwell equations with a fairly general electromagnetic field. For a selected subclass relations are given between the functions determining the metric form, and two new explicit solutions with arbitrary functions of the Einstein-Maxwell equations with a cosmological constant are found. (author)

The effect of body position on the 'hanging drop' method for identifying the extradural space in anaesthetized dogs.

Science.gov (United States)

Naganobu, Kiyokazu; Hagio, Mitsuyoshi

2007-01-01

To assess the accuracy of the 'hanging drop method' for identifying the extradural space in anaesthetized dogs positioned in sternal or lateral recumbency. Prospective randomized-experimental study. Seventeen clinically healthy adult dogs, 10 females and seven males weighing 8.4-26.2 kg. Dogs were positioned in either sternal (n = 8) or lateral (n = 9) recumbency under general anaesthesia. A 20 SWG spinal needle pre-filled with 0.9% saline was advanced through the skin into the lumbosacral extradural space and the response of the saline drop recorded, i.e. whether it: 1) was aspirated from the hub into the needle; 2) remained within the hub, or 3) moved synchronously with i) spontaneous respiration, ii) heart beat or iii) manual lung inflation. The position of the needle tip was ultimately determined by positive contrast radiography. One dog positioned in lateral recumbency was excluded from the study because bleeding occurred from the needle hub. Saline was aspirated into the needle in seven of eight dogs held in sternal recumbency but in none of the dogs positioned in lateral recumbency. Accurate needle tip placement in the extradural space was confirmed by positive contrast radiography in all dogs. The 'hanging drop' method, when performed with a spinal needle, appears to be a useful technique for identifying the location of the extradural space in anaesthetized medium-sized dogs positioned in sternal, but not in lateral recumbency. The technique may yield 'false negative' results when performed in dogs positioned in sternal recumbency.

A dynamic programming algorithm for the space allocation and aisle positioning problem

DEFF Research Database (Denmark)

Bodnar, Peter; Lysgaard, Jens

2014-01-01

The space allocation and aisle positioning problem (SAAPP) in a material handling system with gravity flow racks is the problem of minimizing the total number of replenishments over a period subject to practical constraints related to the need for aisles granting safe and easy access to storage...

Use of Geodetic Surveys of Leveling Lines and Dry Tilt Arrays to Study Faults and Volcanoes in Undergraduate Field Geophysics Classes

Science.gov (United States)

Polet, J.; Alvarez, K.; Elizondo, K.

2017-12-01

In the early 1980's and 1990's numerous leveling lines and dry tilt arrays were installed throughout Central and Southern California by United States Geological Survey scientists and other researchers (e.g. Sylvester, 1985). These lines or triangular arrays of geodetic monuments commonly straddle faults or have been installed close to volcanic areas, where significant motion is expected over relatively short time periods. Over the past year, we have incorporated geodetic surveys of these arrays as part of our field exercises in undergraduate and graduate level classes on topics such as shallow subsurface geophysics and field geophysics. In some cases, the monuments themselves first had to be located based on only limited information, testing students' Brunton use and map reading skills. Monuments were then surveyed using total stations and global navigation satellite system (GNSS) receivers, using a variety of experimental procedures. The surveys were documented with tables, photos, maps and graphs in field reports, as well as in wiki pages created by student groups for a geophysics field class this June. The measurements were processed by the students and compared with similar data from surveys conducted soon after installation of the arrays, to analyze the deformation that occurred over the last few decades. The different geodetic techniques were also compared and an error analysis was conducted. The analysis and processing of these data challenged and enhanced students' quantitative literacy and technology skills. The final geodetic measurements are being incorporated into several senior and MSc thesis projects. Further surveys are planned for additional classes, in topics that could include seismology, geodesy, volcanology and global geophysics. We are also considering additional technologies, such as structure from motion (SfM) photogrammetry.

Accuracy improvement techniques in Precise Point Positioning method using multiple GNSS constellations

Science.gov (United States)

Vasileios Psychas, Dimitrios; Delikaraoglou, Demitris

2016-04-01

The future Global Navigation Satellite Systems (GNSS), including modernized GPS, GLONASS, Galileo and BeiDou, offer three or more signal carriers for civilian use and much more redundant observables. The additional frequencies can significantly improve the capabilities of the traditional geodetic techniques based on GPS signals at two frequencies, especially with regard to the availability, accuracy, interoperability and integrity of high-precision GNSS applications. Furthermore, highly redundant measurements can allow for robust simultaneous estimation of static or mobile user states including more parameters such as real-time tropospheric biases and more reliable ambiguity resolution estimates. This paper presents an investigation and analysis of accuracy improvement techniques in the Precise Point Positioning (PPP) method using signals from the fully operational (GPS and GLONASS), as well as the emerging (Galileo and BeiDou) GNSS systems. The main aim was to determine the improvement in both the positioning accuracy achieved and the time convergence it takes to achieve geodetic-level (10 cm or less) accuracy. To this end, freely available observation data from the recent Multi-GNSS Experiment (MGEX) of the International GNSS Service, as well as the open source program RTKLIB were used. Following a brief background of the PPP technique and the scope of MGEX, the paper outlines the various observational scenarios that were used in order to test various data processing aspects of PPP solutions with multi-frequency, multi-constellation GNSS systems. Results from the processing of multi-GNSS observation data from selected permanent MGEX stations are presented and useful conclusions and recommendations for further research are drawn. As shown, data fusion from GPS, GLONASS, Galileo and BeiDou systems is becoming increasingly significant nowadays resulting in a position accuracy increase (mostly in the less favorable East direction) and a large reduction of convergence

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

Science.gov (United States)

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.

Improvements in Space Geodesy Data Discovery at the CDDIS

Science.gov (United States)

Noll, C.; Pollack, N.; Michael, P.

2011-01-01

The Crustal Dynamics Data Information System (CDDIS) supports data archiving and distribution activities for the space geodesy and geodynamics community. The main objectives of the system are to store space geodesy and geodynamics related data products in a central data bank. to maintain information about the archival of these data, and to disseminate these data and information in a timely manner to a global scientific research community. The archive consists of GNSS, laser ranging, VLBI, and DORIS data sets and products derived from these data. The CDDIS is one of NASA's Earth Observing System Data and Information System (EOSDIS) distributed data centers; EOSDIS data centers serve a diverse user community and arc tasked to provide facilities to search and access science data and products. Several activities are currently under development at the CDDIS to aid users in data discovery, both within the current community and beyond. The CDDIS is cooperating in the development of Geodetic Seamless Archive Centers (GSAC) with colleagues at UNAVCO and SIO. TIle activity will provide web services to facilitate data discovery within and across participating archives. In addition, the CDDIS is currently implementing modifications to the metadata extracted from incoming data and product files pushed to its archive. These enhancements will permit information about COOlS archive holdings to be made available through other data portals such as Earth Observing System (EOS) Clearinghouse (ECHO) and integration into the Global Geodetic Observing System (GGOS) portal.

The impact of using jason-1 and cryosat-2 geodetic mission altimetry for gravity field modeling

DEFF Research Database (Denmark)

Andersen, Ole Baltazar; Jain, Maulik; Knudsen, Per

2016-01-01

Since the release of the Danish Technical University DTU10 global marine gravity field in 2010, the amount of geodetic mission altimetry data has nearly tripled. The Cryosat-2 satellite have provided data along its 369 day near repeat since 2010 and as of May 2012 the Jason-1 satellite has been o...

Positional control of space robot manipulator

Science.gov (United States)

Kurochkin, Vladislav; Shymanchuk, Dzmitry

2018-05-01

In this article the mathematical model of a planar space robot manipulator is under study. The space robot manipulator represents a solid body with attached manipulators. The system of equations of motion is determined using the Lagrange's equations. The control problem concerning moving the robot to a given point and return it to a given trajectory in the phase space is solved. Changes of generalized coordinates and necessary control actions are plotted for a specific model.

Accuracy assessment of Precise Point Positioning with multi-constellation GNSS data under ionospheric scintillation effects

Directory of Open Access Journals (Sweden)

Marques Haroldo Antonio

2018-01-01

Full Text Available GPS and GLONASS are currently the Global Navigation Satellite Systems (GNSS with full operational capacity. The integration of GPS, GLONASS and future GNSS constellations can provide better accuracy and more reliability in geodetic positioning, in particular for kinematic Precise Point Positioning (PPP, where the satellite geometry is considered a limiting factor to achieve centimeter accuracy. The satellite geometry can change suddenly in kinematic positioning in urban areas or under conditions of strong atmospheric effects such as for instance ionospheric scintillation that may degrade satellite signal quality, causing cycle slips and even loss of lock. Scintillation is caused by small scale irregularities in the ionosphere and is characterized by rapid changes in amplitude and phase of the signal, which are more severe in equatorial and high latitudes geomagnetic regions. In this work, geodetic positioning through the PPP method was evaluated with integrated GPS and GLONASS data collected in the equatorial region under varied scintillation conditions. The GNSS data were processed in kinematic PPP mode and the analyses show accuracy improvements of up to 60% under conditions of strong scintillation when using multi-constellation data instead of GPS data alone. The concepts and analyses related to the ionospheric scintillation effects, the mathematical model involved in PPP with GPS and GLONASS data integration as well as accuracy assessment with data collected under ionospheric scintillation effects are presented.

Accuracy assessment of Precise Point Positioning with multi-constellation GNSS data under ionospheric scintillation effects

Science.gov (United States)

Marques, Haroldo Antonio; Marques, Heloísa Alves Silva; Aquino, Marcio; Veettil, Sreeja Vadakke; Monico, João Francisco Galera

2018-02-01

GPS and GLONASS are currently the Global Navigation Satellite Systems (GNSS) with full operational capacity. The integration of GPS, GLONASS and future GNSS constellations can provide better accuracy and more reliability in geodetic positioning, in particular for kinematic Precise Point Positioning (PPP), where the satellite geometry is considered a limiting factor to achieve centimeter accuracy. The satellite geometry can change suddenly in kinematic positioning in urban areas or under conditions of strong atmospheric effects such as for instance ionospheric scintillation that may degrade satellite signal quality, causing cycle slips and even loss of lock. Scintillation is caused by small scale irregularities in the ionosphere and is characterized by rapid changes in amplitude and phase of the signal, which are more severe in equatorial and high latitudes geomagnetic regions. In this work, geodetic positioning through the PPP method was evaluated with integrated GPS and GLONASS data collected in the equatorial region under varied scintillation conditions. The GNSS data were processed in kinematic PPP mode and the analyses show accuracy improvements of up to 60% under conditions of strong scintillation when using multi-constellation data instead of GPS data alone. The concepts and analyses related to the ionospheric scintillation effects, the mathematical model involved in PPP with GPS and GLONASS data integration as well as accuracy assessment with data collected under ionospheric scintillation effects are presented.

Uncertainty assessment in geodetic network adjustment by combining GUM and Monte-Carlo-simulations

Science.gov (United States)

Niemeier, Wolfgang; Tengen, Dieter

2017-06-01

In this article first ideas are presented to extend the classical concept of geodetic network adjustment by introducing a new method for uncertainty assessment as two-step analysis. In the first step the raw data and possible influencing factors are analyzed using uncertainty modeling according to GUM (Guidelines to the Expression of Uncertainty in Measurements). This approach is well established in metrology, but rarely adapted within Geodesy. The second step consists of Monte-Carlo-Simulations (MC-simulations) for the complete processing chain from raw input data and pre-processing to adjustment computations and quality assessment. To perform these simulations, possible realizations of raw data and the influencing factors are generated, using probability distributions for all variables and the established concept of pseudo-random number generators. Final result is a point cloud which represents the uncertainty of the estimated coordinates; a confidence region can be assigned to these point clouds, as well. This concept may replace the common concept of variance propagation and the quality assessment of adjustment parameters by using their covariance matrix. It allows a new way for uncertainty assessment in accordance with the GUM concept for uncertainty modelling and propagation. As practical example the local tie network in "Metsähovi Fundamental Station", Finland is used, where classical geodetic observations are combined with GNSS data.

Geodetic slip solutions for the Mw=7.4 Champerico (Guatemala) subduction earthquake of November 7 2012

Science.gov (United States)

Ellis, Andria; DeMets, Charles; Briole, Pierre; Molina, Enrique; Flores, Omar; Rivera, Jeffrey; Lasserre, Cécile; Lyon-Caen, Hélène; Lord, Neal

2014-05-01

As the first large subduction thrust earthquake off the coast of western Guatemala in the past 50 years, the 7 November 2012 Mw=7.4 earthquake offers the first opportunity for a geodetic study of coseismic and postseismic behavior for a segment of the Middle America trench where frictional coupling makes a transition from weak coupling off the coast of El Salvador to strong coupling in southern Mexico. Processing of continuous GPS measurements at 19 stations in Guatemala, El Salvador, and southern Mexico, and at 7 campaign points in Guatemala defines a highly consistent pattern of coseismic offsets during the earthquake, ranging from 47±5 mm of SW movement just inland from the earthquake epicenter to a few mm at sites located in northern Guatemala. Inversions of these offsets to find their best-fitting fault-slip solution in an elastic half space give a geodetic earthquake moment ranging between 0.75 and 1.1 x 1020 Nm, slightly smaller than the seismic estimates that range between 1.2 and 1.45 x 1020 Nm. Slip inversion using a constant slip model, assuming 293° and 29° for the fault azimuth and dip angle, indicates a nearly reverse slip of 2.8 m (rake 78°) on a fault plane 42 km-long and 20 km-wide, centered at 26 km depth. A variable slip inversion indicates that slip concentrated above depths of 40 km may have extended updip to the trench and reached a maximum of only 0.8 m, less than one-sixth the maximum slip indicated by a recent slip solution (5.3 m) obtained from waveform inversion of seismological data. Detailed model comparisons will be discussed. Transient postseismic displacements have been recorded at the nearby continuous GPS sites with amplitudes reaching 20-25 mm at some stations. The duration of the phenomenon is short: using an exponential-decay model, the estimated decay time is 90 ± 10 days. This postseismic signal is consistent with afterslip along a significantly broader area (+50%) of the subduction interface than ruptured coseismically

78 FR 23598 - National Space-Based Positioning, Navigation, and Timing (PNT) Advisory Board; Meeting

Science.gov (United States)

2013-04-19

..., Public Law 92-463, as amended, and the President's 2004 U.S. Space-Based Positioning, Navigation, and...: The Melrose Hotel, 2430 Pennsylvania Ave NW., Washington, DC 20037. FOR FURTHER INFORMATION CONTACT...

LibHalfSpace: A C++ object-oriented library to study deformation and stress in elastic half-spaces

Science.gov (United States)

Ferrari, Claudio; Bonafede, Maurizio; Belardinelli, Maria Elina

2016-11-01

The study of deformation processes in elastic half-spaces is widely employed for many purposes (e.g. didactic, scientific investigation of real processes, inversion of geodetic data, etc.). We present a coherent programming interface containing a set of tools designed to make easier and faster the study of processes in an elastic half-space. LibHalfSpace is presented in the form of an object-oriented library. A set of well known and frequently used source models (Mogi source, penny shaped horizontal crack, inflating spheroid, Okada rectangular dislocation, etc.) are implemented to describe the potential usage and the versatility of the library. The common interface given to library tools enables us to switch easily among the effects produced by different deformation sources that can be monitored at the free surface. Furthermore, the library also offers an interface which simplifies the creation of new source models exploiting the features of object-oriented programming (OOP). These source models can be built as distributions of rectangular boundary elements. In order to better explain how new models can be deployed some examples are included in the library.

Precision Measurement of the Position-Space Wave Functions of Gravitationally Bound Ultracold Neutrons

Directory of Open Access Journals (Sweden)

Y. Kamiya

2014-01-01

Full Text Available Gravity is the most familiar force at our natural length scale. However, it is still exotic from the view point of particle physics. The first experimental study of quantum effects under gravity was performed using a cold neutron beam in 1975. Following this, an investigation of gravitationally bound quantum states using ultracold neutrons was started in 2002. This quantum bound system is now well understood, and one can use it as a tunable tool to probe gravity. In this paper, we review a recent measurement of position-space wave functions of such gravitationally bound states and discuss issues related to this analysis, such as neutron loss models in a thin neutron guide, the formulation of phase space quantum mechanics, and UCN position sensitive detectors. The quantum modulation of neutron bound states measured in this experiment shows good agreement with the prediction from quantum mechanics.

78 FR 65006 - National Space-Based Positioning, Navigation, and Timing (PNT) Advisory Board; Meeting

Science.gov (United States)

2013-10-30

..., Public Law 92-463, as amended, and the President's 2004 U.S. Space-Based Positioning, Navigation, and.... ADDRESSES: The Omni Shoreham Hotel, 2500 Calvert Street NW., Washington, DC 20008. FOR FURTHER INFORMATION...

Building resilience of the Global Positioning System to space weather

Science.gov (United States)

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.

Isotropic oscillator in the space of constant positive curvature. Interbasis expansions

International Nuclear Information System (INIS)

Akopyan, E.M.; Pogosyan, G.S.; Sisakyan, A.N.; Vinitskij, S.I.

1997-01-01

The Schroedinger equation is thoroughly analysed for the isotropic oscillator in the three-dimensional space of constant positive curvature in the spherical and cylindrical systems of coordinates. The expansion coefficients between the spherical and cylindrical bases of the oscillator are calculated. It is shown that the relevant coefficients are expressed through the generalised hypergeometric functions 4 F 3 of the unit argument or 6j Racah symbols extended over their indices to the region of real values. Limiting transitions to a free motion and flat space are considered in detail. Elliptic bases of the oscillator are constructed in the form of expansion over the spherical and cylindrical bases. The corresponding expansion coefficients are shown to obey the three-term recurrence relations expansion coefficients are shown to obey the three-term recurrence relations

Space Environment Effects on Materials at Different Positions and Operational Periods of ISS

Science.gov (United States)

Kimoto, Yugo; Ichikawa, Shoichi; Miyazaki, Eiji; Matsumoto, Koji; Ishizawa, Junichiro; Shimamura, Hiroyuki; Yamanaka, Riyo; Suzuki, Mineo

2009-01-01

A space materials exposure experiment was condcuted on the exterior of the Russian Service Module (SM) of the International Space Station (ISS) using the Micro-Particles Capturer and Space Environment Exposure Device (MPAC&SEED) of the Japan Aerospace Exploration Agency (JAXA). Results reveal artificial environment effects such as sample contamination, attitude change effects on AO fluence, and shading effects of UV on ISS. The sample contamination was coming from ISS components. The particles attributed to micrometeoroids and/or debris captured by MPAC might originate from the ISS solar array. Another MPAC&SEED will be aboard the Exposure Facility of the Japanese Experiment Module, KIBO Exposure Facility (EF) on ISS. The JEM/MPAC&SEED is attached to the Space Environment Data Acquisition Equipment-Attached Payload (SEDA-AP) and is exposed to space. Actually, SEDA-AP is a payload on EF to be launched by Space Shuttle flight 2J/A. In fact, SEDA-AP has space environment monitors such as a high-energy particle monitor, atomic oxygen monitor, and plasma monitor to measure in-situ natural space environment data during JEM/MPAC&SEED exposure. Some exposure samples for JEM/MPAC&SEED are identical to SM/MPAC&SEED samples. Consequently, effects on identical materials at different positions and operation periods of ISS will be evaluated. This report summarizes results from space environment monitoring samples for atomic oxygen analysis on SM/MPAC&SEED, along with experimental plans for JEM/MPAC&SEED.

Conference at Caltech on Riesz Spaces, Positive Operators, and their Applications to Economics

CERN Document Server

Aliprantis, Charalambos D; Luxemburg, Wilhelmus A J

1991-01-01

Over the last fifty years advanced mathematical tools have become an integral part in the development of modern economic theory. Economists continue to invoke sophisticated mathematical techniques and ideas in order to understand complex economic and social problems. In the last ten years the theory of Riesz spaces (vector lattices) has been successfully applied to economic theory. By now it is understood relatively well that the lattice structure of Riesz spaces can be employed to capture and interpret several economic notions. On April 16-20, 1990, a small conference on Riesz Spaces, Positive Opera­ tors, and their Applications to Economics took place at the California Institute of Technology. The purpose of the conference was to bring mathematicians special­ ized in Riesz Spaces and economists specialized in General Equilibrium together to exchange ideas and advance the interdisciplinary cooperation between math­ ematicians and economists. This volume is a collection of papers that represent the talks a...

A case for inherent geometric and geodetic accuracy in remotely sensed VNIR and SWIR imaging products

Science.gov (United States)

Driver, J. M.

1982-01-01

Significant aberrations can occur in acquired images which, unless compensated on board the spacecraft, can seriously impair throughput and timeliness for typical Earth observation missions. Conceptual compensations options are advanced to enable acquisition of images with inherent geometric and geodetic accuracy. Research needs are identified which, when implemented, can provide inherently accurate images. Agressive pursuit of these research needs is recommended.

Thin-plate spline quadrature of geodetic integrals

Science.gov (United States)

Vangysen, Herman

1989-01-01

Thin-plate spline functions (known for their flexibility and fidelity in representing experimental data) are especially well-suited for the numerical integration of geodetic integrals in the area where the integration is most sensitive to the data, i.e., in the immediate vicinity of the evaluation point. Spline quadrature rules are derived for the contribution of a circular innermost zone to Stoke's formula, to the formulae of Vening Meinesz, and to the recursively evaluated operator L(n) in the analytical continuation solution of Molodensky's problem. These rules are exact for interpolating thin-plate splines. In cases where the integration data are distributed irregularly, a system of linear equations needs to be solved for the quadrature coefficients. Formulae are given for the terms appearing in these equations. In case the data are regularly distributed, the coefficients may be determined once-and-for-all. Examples are given of some fixed-point rules. With such rules successive evaluation, within a circular disk, of the terms in Molodensky's series becomes relatively easy. The spline quadrature technique presented complements other techniques such as ring integration for intermediate integration zones.

Positive-definite functions and unitary representations of locally compact groups in a Hilbert space

International Nuclear Information System (INIS)

Gali, I.M.; Okb el-Bab, A.S.; Hassan, H.M.

1977-08-01

It is proved that the necessary and sufficient condition for the existence of an integral representation of a group of unitary operators in a Hilbert space is that it is positive-definite and continuous in some topology

New superintegrable models with position-dependent mass from Bertrand's Theorem on curved spaces

Energy Technology Data Exchange (ETDEWEB)

Ballesteros, A; Herranz, F J [Departamento de Fisica, Universidad de Burgos, E-09001 Burgos (Spain); Enciso, A [Departamento de Fisica Teorica II, Universidad Complutense, E-28040 Madrid (Spain); Ragnisco, O; Riglioni, D, E-mail: angelb@ubu.es, E-mail: aenciso@fis.ucm.es, E-mail: fjherranz@ubu.es, E-mail: ragnisco@fis.uniroma3.it, E-mail: riglioni@fis.uniroma3.it [Dipartimento di Fisica, Universita di Roma Tre and Instituto Nazionale di Fisica Nucleare sezione di Roma Tre, Via Vasca Navale 84, I-00146 Roma (Italy)

2011-03-01

A generalized version of Bertrand's theorem on spherically symmetric curved spaces is presented. This result is based on the classification of (3+1)-dimensional (Lorentzian) Bertrand spacetimes, that gives rise to two families of Hamiltonian systems defined on certain 3-dimensional (Riemannian) spaces. These two systems are shown to be either the Kepler or the oscillator potentials on the corresponding Bertrand spaces, and both of them are maximally superintegrable. Afterwards, the relationship between such Bertrand Hamiltonians and position-dependent mass systems is explicitly established. These results are illustrated through the example of a superintegrable (nonlinear) oscillator on a Bertrand-Darboux space, whose quantization and physical features are also briefly addressed.

An improved evaluation of the seismic/geodetic deformation-rate ratio for the Zagros Fold-and-Thrust collisional belt

Science.gov (United States)

Palano, Mimmo; Imprescia, Paola; Agnon, Amotz; Gresta, Stefano

2018-04-01

We present an improved picture of the ongoing crustal deformation field for the Zagros Fold-and-Thrust Belt continental collision zone by using an extensive combination of both novel and published GPS observations. The main results define the significant amount of oblique Arabia-Eurasia convergence currently being absorbed within the Zagros: right-lateral shear along the NW trending Main Recent fault in NW Zagros and accommodated between fold-and-thrust structures and NS right-lateral strike-slip faults on Southern Zagros. In addition, taking into account the 1909-2016 instrumental seismic catalogue, we provide a statistical evaluation of the seismic/geodetic deformation-rate ratio for the area. On Northern Zagros and on the Turkish-Iranian Plateau, a moderate to large fraction (˜49 and >60 per cent, respectively) of the crustal deformation occurs seismically. On the Sanandaj-Sirjan zone, the seismic/geodetic deformation-rate ratio suggests that a small to moderate fraction (<40 per cent) of crustal deformation occurs seismically; locally, the occurrence of large historic earthquakes (M ≥ 6) coupled with the high geodetic deformation, could indicate overdue M ≥ 6 earthquakes. On Southern Zagros, aseismic strain dominates crustal deformation (the ratio ranges in the 15-33 per cent interval). Such aseismic deformation is probably related to the presence of the weak evaporitic Hormuz Formation which allows the occurrence of large aseismic motion on both subhorizontal faults and surfaces of décollement. These results, framed into the seismotectonic framework of the investigated region, confirm that the fold-and-thrust-dominated deformation is driven by buoyancy forces; by contrast, the shear-dominated deformation is primary driven by plate stresses.

CDDIS: NASA's Archive of Space Geodesy Data and Products Supporting GGOS

Science.gov (United States)

Noll, Carey; Michael, Patrick

2016-01-01

The Crustal Dynamics Data Information System (CDDIS) supports data archiving and distribution activities for the space geodesy and geodynamics community. The main objectives of the system are to store space geodesy and geodynamics related data and products in a central archive, to maintain information about the archival of these data,to disseminate these data and information in a timely manner to a global scientific research community, and provide user based tools for the exploration and use of the archive. The CDDIS data system and its archive is a key component in several of the geometric services within the International Association of Geodesy (IAG) and its observing systemthe Global Geodetic Observing System (GGOS), including the IGS, the International DORIS Service (IDS), the International Laser Ranging Service (ILRS), the International VLBI Service for Geodesy and Astrometry (IVS), and the International Earth Rotation and Reference Systems Service (IERS). The CDDIS provides on-line access to over 17 Tbytes of dataand derived products in support of the IAG services and GGOS. The systems archive continues to grow and improve as new activities are supported and enhancements are implemented. Recently, the CDDIS has established a real-time streaming capability for GNSS data and products. Furthermore, enhancements to metadata describing the contents ofthe archive have been developed to facilitate data discovery. This poster will provide a review of the improvements in the system infrastructure that CDDIS has made over the past year for the geodetic community and describe future plans for the system.

Application of ray-traced tropospheric slant delays to geodetic VLBI analysis

Science.gov (United States)

Hofmeister, Armin; Böhm, Johannes

2017-08-01

The correction of tropospheric influences via so-called path delays is critical for the analysis of observations from space geodetic techniques like the very long baseline interferometry (VLBI). In standard VLBI analysis, the a priori slant path delays are determined using the concept of zenith delays, mapping functions and gradients. The a priori use of ray-traced delays, i.e., tropospheric slant path delays determined with the technique of ray-tracing through the meteorological data of numerical weather models (NWM), serves as an alternative way of correcting the influences of the troposphere on the VLBI observations within the analysis. In the presented research, the application of ray-traced delays to the VLBI analysis of sessions in a time span of 16.5 years is investigated. Ray-traced delays have been determined with program RADIATE (see Hofmeister in Ph.D. thesis, Department of Geodesy and Geophysics, Faculty of Mathematics and Geoinformation, Technische Universität Wien. http://resolver.obvsg.at/urn:nbn:at:at-ubtuw:1-3444, 2016) utilizing meteorological data provided by NWM of the European Centre for Medium-Range Weather Forecasts (ECMWF). In comparison with a standard VLBI analysis, which includes the tropospheric gradient estimation, the application of the ray-traced delays to an analysis, which uses the same parameterization except for the a priori slant path delay handling and the used wet mapping factors for the zenith wet delay (ZWD) estimation, improves the baseline length repeatability (BLR) at 55.9% of the baselines at sub-mm level. If no tropospheric gradients are estimated within the compared analyses, 90.6% of all baselines benefit from the application of the ray-traced delays, which leads to an average improvement of the BLR of 1 mm. The effects of the ray-traced delays on the terrestrial reference frame are also investigated. A separate assessment of the RADIATE ray-traced delays is carried out by comparison to the ray-traced delays from the

Encouraging Deep Approach to Learning in Civil and Geodetic Engineering

Directory of Open Access Journals (Sweden)

Gašper Mrak

2016-10-01

Full Text Available This paper presents activities and changes applied to the teaching process within selected courses offered by Faculty of civil and geodetic engineering, University of Ljubljana, Slovenia. Theoretical background, evaluated from the point of the technical education needs, is presented. It can be seen that special focus has to be made to the students' motivation for deep learning which guarantees optimal balance between acquisition of concepts and skills, information processing and integration of fragmented pieces of knowledge into complex structures. Three case studies used to test theoretical points of departure are presented. Results of the introduced novelties and changes have been evaluated through the assessment of knowledge, students' satisfaction and teaching staff evaluations. For conclusive results, monitoring over a longer period of time should be conducted.

Relativistic effects on complexity indexes in atoms in position and momentum spaces

International Nuclear Information System (INIS)

Maldonado, P.; Sarsa, A.; Buendia, E.; Galvez, F.J.

2010-01-01

Three different statistical measures of complexity are explored for the atoms He to Ra. The measures are analysed in both position and momentum spaces. Relativistic effects on the complexity indexes are systematically studied. These effects are discussed in terms of the information content factor and the disorder terms of the complexity indexes. Relativistic and non-relativistic complexity indexes are calculated from Optimized Effective Potential densities.

Single-frequency receivers as master permanent stations in GNSS networks: precision and accuracy of the positioning in mixed networks

Science.gov (United States)

Dabove, Paolo; Manzino, Ambrogio Maria

2015-04-01

The use of GPS/GNSS instruments is a common practice in the world at both a commercial and academic research level. Since last ten years, Continuous Operating Reference Stations (CORSs) networks were born in order to achieve the possibility to extend a precise positioning more than 15 km far from the master station. In this context, the Geomatics Research Group of DIATI at the Politecnico di Torino has carried out several experiments in order to evaluate the achievable precision obtainable with different GNSS receivers (geodetic and mass-market) and antennas if a CORSs network is considered. This work starts from the research above described, in particular focusing the attention on the usefulness of single frequency permanent stations in order to thicken the existing CORSs, especially for monitoring purposes. Two different types of CORSs network are available today in Italy: the first one is the so called "regional network" and the second one is the "national network", where the mean inter-station distances are about 25/30 and 50/70 km respectively. These distances are useful for many applications (e.g. mobile mapping) if geodetic instruments are considered but become less useful if mass-market instruments are used or if the inter-station distance between master and rover increases. In this context, some innovative GNSS networks were developed and tested, analyzing the performance of rover's positioning in terms of quality, accuracy and reliability both in real-time and post-processing approach. The use of single frequency GNSS receivers leads to have some limits, especially due to a limited baseline length, the possibility to obtain a correct fixing of the phase ambiguity for the network and to fix the phase ambiguity correctly also for the rover. These factors play a crucial role in order to reach a positioning with a good level of accuracy (as centimetric o better) in a short time and with an high reliability. The goal of this work is to investigate about the

X-cephalometric study of different parts of the upper airway space and changes in hyoid position following mandibular fractures.

Science.gov (United States)

Chen, L-J; Zhao, M-C; Pan, X-F; Wei, Y-Q; Wang, D-Y

2013-09-01

This study analyses the different parts of the upper airway space and the changes in hyoid position. The results provide a clinical reference for developing timely and effective treatment programmes for patients with mandibular fractures caused by maxillofacial trauma. Standard X-cephalometric measurements of the lateral skull of 210 subjects were taken. The subjects were divided into four fracture groups: condylar, mandibular angle, mandibular body, and parasymphyseal. The radiographs of the mandibular fracture groups were compared with the normal occlusion group to analyse the upper airway space and the changes in hyoid position. Different types of fractures have different effects on the upper airway space. Bilateral mandibular body fracture and the parasymphyseal fracture have a significant influence on the lower oropharyngeal and laryngopharyngeal airway spaces, with serious obstructions severely restricting the ventilatory function of patients. Fractures at different parts of the mandibular structure are closely related to the upper airway and hyoid position.

Study of electric field distorted by space charges under positive lightning impulse voltage

Science.gov (United States)

Wang, Zezhong; Geng, Yinan

2018-03-01

Actually, many insulation problems are related to electric fields. And measuring electric fields is an important research topic of high-voltage engineering. In particular, the electric field distortion caused by space charge is the basis of streamer theory, and thus quantitatively measuring the Poisson electric field caused by space charge is significant to researching the mechanism of air gap discharge. In this paper, we used our photoelectric integrated sensor to measure the electric field distribution in a 1-m rod-plane gap under positive lightning impulse voltage. To verify the reliability of this quantitative measurement, we compared the measured results with calculated results from a numerical simulation. The electric-field time domain waveforms on the axis of the 1-m rod-plane out of the space charge zone were measured with various electrodes. The Poisson electric fields generated by space charge were separated from the Laplace electric field generated by applied voltages, and the amplitudes and variations were measured for various applied voltages and at various locations. This work also supplies the feasible basis for directly measuring strong electric field under high voltage.

A Kalman Filter Implementation for Precision Improvement in Low-Cost GPS Positioning of Tractors

Science.gov (United States)

Gomez-Gil, Jaime; Ruiz-Gonzalez, Ruben; Alonso-Garcia, Sergio; Gomez-Gil, Francisco Javier

2013-01-01

Low-cost GPS receivers provide geodetic positioning information using the NMEA protocol, usually with eight digits for latitude and nine digits for longitude. When these geodetic coordinates are converted into Cartesian coordinates, the positions fit in a quantization grid of some decimeters in size, the dimensions of which vary depending on the point of the terrestrial surface. The aim of this study is to reduce the quantization errors of some low-cost GPS receivers by using a Kalman filter. Kinematic tractor model equations were employed to particularize the filter, which was tuned by applying Monte Carlo techniques to eighteen straight trajectories, to select the covariance matrices that produced the lowest Root Mean Square Error in these trajectories. Filter performance was tested by using straight tractor paths, which were either simulated or real trajectories acquired by a GPS receiver. The results show that the filter can reduce the quantization error in distance by around 43%. Moreover, it reduces the standard deviation of the heading by 75%. Data suggest that the proposed filter can satisfactorily preprocess the low-cost GPS receiver data when used in an assistance guidance GPS system for tractors. It could also be useful to smooth tractor GPS trajectories that are sharpened when the tractor moves over rough terrain. PMID:24217355

Multiple positive solutions for second order impulsive boundary value problems in Banach spaces

Directory of Open Access Journals (Sweden)

Zhi-Wei Lv

2010-06-01

Full Text Available By means of the fixed point index theory of strict set contraction operators, we establish new existence theorems on multiple positive solutions to a boundary value problem for second-order impulsive integro-differential equations with integral boundary conditions in a Banach space. Moreover, an application is given to illustrate the main result.

Data Records derived from GEOSAT Geodetic Mission (GM) and Exact Repeat Mission (ERM) data from 30 March 1985 to 31 December 1989

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This collection contains Sensor Data Records (SDRs), Geodetic Data Records (GDRs), Waveform Data Records (WDRs), and Crossover Difference data Records (XDRs) from...

Geodetic, Geologic and Seismic Interdisciplinary Research of Tectonically Caused Movements in the Wider Area of the City of Zagreb

Science.gov (United States)

Dapo, A.; Pribicevic, B.; Herak, M.; Prelogovic, E.

2012-04-01

Since the last great earthquake in 1880 which shook the Zagreb area with IX° MCS, tectonic movements and models of numerous Zagreb faults have been the focal point of Croatian geologists, seismologists and in the last 15 years also geodetic scientists, who all have been working in the scope of their scientific branches on bringing the light to the tectonic mechanisms in the wider Zagreb area. Since it is tectonically very active area and being the Capitol city of the Croatia with very high population density it is of utmost importance to understand those mechanisms and to according to them find the best possible measures for protecting people and valuables. Best results are certainly going to be achieved through the interdisciplinary approach. That is why this paper presents first interdisciplinary results from geodetic, geologic and seismic researches and their contribution to the collective knowledge about tectonic movements in the wider area of the City of Zagreb.

Evaluating Commercial and Private Cloud Services for Facility-Scale Geodetic Data Access, Analysis, and Services

Science.gov (United States)

Meertens, C. M.; Boler, F. M.; Ertz, D. J.; Mencin, D.; Phillips, D.; Baker, S.

2017-12-01

UNAVCO, in its role as a NSF facility for geodetic infrastructure and data, has succeeded for over two decades using on-premises infrastructure, and while the promise of cloud-based infrastructure is well-established, significant questions about suitability of such infrastructure for facility-scale services remain. Primarily through the GeoSciCloud award from NSF EarthCube, UNAVCO is investigating the costs, advantages, and disadvantages of providing its geodetic data and services in the cloud versus using UNAVCO's on-premises infrastructure. (IRIS is a collaborator on the project and is performing its own suite of investigations). In contrast to the 2-3 year time scale for the research cycle, the time scale of operation and planning for NSF facilities is for a minimum of five years and for some services extends to a decade or more. Planning for on-premises infrastructure is deliberate, and migrations typically take months to years to fully implement. Migrations to a cloud environment can only go forward with similar deliberate planning and understanding of all costs and benefits. The EarthCube GeoSciCloud project is intended to address the uncertainties of facility-level operations in the cloud. Investigations are being performed in a commercial cloud environment (Amazon AWS) during the first year of the project and in a private cloud environment (NSF XSEDE resource at the Texas Advanced Computing Center) during the second year. These investigations are expected to illuminate the potential as well as the limitations of running facility scale production services in the cloud. The work includes running parallel equivalent cloud-based services to on premises services and includes: data serving via ftp from a large data store, operation of a metadata database, production scale processing of multiple months of geodetic data, web services delivery of quality checked data and products, large-scale compute services for event post-processing, and serving real time data

Direction for the Future - Successive Acceleration of Positive and Negative Ions Applied to Space Propulsion

CERN Document Server

Aanesland, A.; Popelier, L.; Chabert, P.

2013-12-16

Electrical space thrusters show important advantages for applications in outer space compared to chemical thrusters, as they allow a longer mission lifetime with lower weight and propellant consumption. Mature technologies on the market today accelerate positive ions to generate thrust. The ion beam is neutralized by electrons downstream, and this need for an additional neutralization system has some drawbacks related to stability, lifetime and total weight and power consumption. Many new concepts, to get rid of the neutralizer, have been proposed, and the PEGASES ion-ion thruster is one of them. This new thruster concept aims at accelerating both positive and negative ions to generate thrust, such that additional neutralization is redundant. This chapter gives an overview of the concept of electric propulsion and the state of the development of this new ion-ion thruster.

Digital Levelling in Subterranean Spaces

Directory of Open Access Journals (Sweden)

Tomáš Jiřikovský

2007-06-01

Full Text Available For precision levelling works are now more often used digital levels and code-scale staffs. Advantages in (and problems with their application to the regular line-levelling are well known and described. However, when using the digital levelling for measurements in specific local geodetic networks, monitoring networks and inside of buildings and underground spaces, new problems appear with the signalisation of the observed points, readability of the code (non-uniform illumination, temperature changes etc. The article informs about the application of two types of digital levels (Sokkia SDL-2, Trimble Zeiss DiNi 12T in the experimental subterranean levelling network for the basement settlement monitoring of a ten-floor building; the solution of marking of the points, field calibration and the system calibration of digital levels.

Geostatistical Investigations of Displacements on the Basis of Data from the Geodetic Monitoring of a Hydrotechnical Object

Science.gov (United States)

Namysłowska-Wilczyńska, Barbara; Wynalek, Janusz

2017-12-01

Geostatistical methods make the analysis of measurement data possible. This article presents the problems directed towards the use of geostatistics in spatial analysis of displacements based on geodetic monitoring. Using methods of applied (spatial) statistics, the research deals with interesting and current issues connected to space-time analysis, modeling displacements and deformations, as applied to any large-area objects on which geodetic monitoring is conducted (e.g., water dams, urban areas in the vicinity of deep excavations, areas at a macro-regional scale subject to anthropogenic influences caused by mining, etc.). These problems are very crucial, especially for safety assessment of important hydrotechnical constructions, as well as for modeling and estimating mining damage. Based on the geodetic monitoring data, a substantial basic empirical material was created, comprising many years of research results concerning displacements of controlled points situated on the crown and foreland of an exemplary earth dam, and used to assess the behaviour and safety of the object during its whole operating period. A research method at a macro-regional scale was applied to investigate some phenomena connected with the operation of the analysed big hydrotechnical construction. Applying a semivariogram function enabled the spatial variability analysis of displacements. Isotropic empirical semivariograms were calculated and then, theoretical parameters of analytical functions were determined, which approximated the courses of the mentioned empirical variability measure. Using ordinary (block) kriging at the grid nodes of an elementary spatial grid covering the analysed object, the values of the Z* estimated means of displacements were calculated together with the accompanying assessment of uncertainty estimation - a standard deviation of estimation σk. Raster maps of the distribution of estimated averages Z* and raster maps of deviations of estimation σk (in perspective

The analysis of spatial relationship between the rotator cuff and the subacromial space in different arm positions

International Nuclear Information System (INIS)

Zou Yuefen; Wang Dehang; Wang Xiaoning; Li Shener

2003-01-01

Objective: To explore the distance between the acromion and the humerus head at different arm abduction to observe whether it changes or not, to determine at which position the distance is smallest, and to evaluate the relationship between the subacromial space and the rotator cuff. Methods: Fifteen normal volunteers were examined with MRI in six arm positions, and the coronal thin images were obtained with a spin echo sequence. Using a special positioning device, the arm was placed at 0 degree, 30 degree, 60 degree, 90 degree, 120 degree and 150 degree arm abduction, respectively. Of them, 0 degree-90 degree positions were not rotated, while 120 degree and 150 degree positions were slight internal rotated. The minimal distance of acromion-humerus (A-H) and clavicle-humerus (C-H), and the spatial relationship between the rotator cuff and the subacromial space were measured and observed. Results: The values of A-H and C-H at 60 degree - 150 degree arm abduction were obviously smaller than those at 0 degree-30 degree arm abduction (P 0.05). The rotator cuff (mainly supraspinatus tendon) just went through between the acromion and the humerus at 60 degree - 120 degree arm positions but not at 0 degree, 30 degree and 150 degree arm positions. So at 60 degree - 120 degree arm positions, rotator cuff between the humerus and the acromion was often impinged. Conclusion: The closest contact between the supraspinatus tendon and subacromial space occurs at 60 degree - 120 degree abduction. The findings testify that the patients with impingement syndrome have shoulder pain at 60 degree - 120 degree abduction in clinic from etiology and pathology. In the future, MRI-based analyses should allow investigating the morphological basis of the impingement syndrome, choosing the appropriate therapy, and minimizing failure rates of surgery

Positive Emotional Effects of Leisure in Green Spaces in Alleviating Work–Family Spillover in Working Mothers

Directory of Open Access Journals (Sweden)

Po-Ju Chang

2017-07-01

Full Text Available Studies have shown that family and work spillover affects well-being and that leisure activities can alleviate the negative effects of work-related stress on health. However, few studies have focused on investigating the effects of specific leisure activities among specific populations. To examine whether leisure activities in green spaces can promote individual recovery processes and alleviate the effects of work and family spillover on positive emotions, this study applied the effort-recovery model to a population of working mothers. Through online and paper questionnaires, sample data were collected from 221 working mothers in Taiwan. Structural equation modeling was used to test the experimental hypothesis, and mediation analysis was used to determine whether leisure in green spaces is a mediating factor. The results indicated that leisure in green spaces is a mediator of the relationship of negative work and family spillover with positive emotions. In addition, strolls and park visits were found to provide greater psychological benefits to working mothers, compared with picnics.

Positive Emotional Effects of Leisure in Green Spaces in Alleviating Work–Family Spillover in Working Mothers

Science.gov (United States)

Chang, Po-Ju; Bae, So Young

2017-01-01

Studies have shown that family and work spillover affects well-being and that leisure activities can alleviate the negative effects of work-related stress on health. However, few studies have focused on investigating the effects of specific leisure activities among specific populations. To examine whether leisure activities in green spaces can promote individual recovery processes and alleviate the effects of work and family spillover on positive emotions, this study applied the effort-recovery model to a population of working mothers. Through online and paper questionnaires, sample data were collected from 221 working mothers in Taiwan. Structural equation modeling was used to test the experimental hypothesis, and mediation analysis was used to determine whether leisure in green spaces is a mediating factor. The results indicated that leisure in green spaces is a mediator of the relationship of negative work and family spillover with positive emotions. In addition, strolls and park visits were found to provide greater psychological benefits to working mothers, compared with picnics. PMID:28696388

Positive Emotional Effects of Leisure in Green Spaces in Alleviating Work-Family Spillover in Working Mothers.

Science.gov (United States)

Chang, Po-Ju; Bae, So Young

2017-07-11

Studies have shown that family and work spillover affects well-being and that leisure activities can alleviate the negative effects of work-related stress on health. However, few studies have focused on investigating the effects of specific leisure activities among specific populations. To examine whether leisure activities in green spaces can promote individual recovery processes and alleviate the effects of work and family spillover on positive emotions, this study applied the effort-recovery model to a population of working mothers. Through online and paper questionnaires, sample data were collected from 221 working mothers in Taiwan. Structural equation modeling was used to test the experimental hypothesis, and mediation analysis was used to determine whether leisure in green spaces is a mediating factor. The results indicated that leisure in green spaces is a mediator of the relationship of negative work and family spillover with positive emotions. In addition, strolls and park visits were found to provide greater psychological benefits to working mothers, compared with picnics.

Precision positioning of SuperKamiokande with GPS for a long-baseline neutrino oscillation experiment

International Nuclear Information System (INIS)

Noumi, H.; Ieiri, M.; Ishii, H.; Katoh, Y.; Minakawa, M.; Nakamura, K.; Nishikawa, K.; Suzuki, Y.; Takasaki, M.; Tanaka, K.H.; Yamanoi, Y.; Kurodai, M.; Kasa, H.; Yoshimura, K.

1997-01-01

A positioning of the neutrino detector superkamiokande (SK) was made for a long-baseline neutrino oscillation experiment planned at KEK. For positioning, global positioning system (GPS) was employed. It has been demonstrated that GPS is of practical use for measuring the positions of SK and KEK, being 250 km distance from each other, to a better resolution. The geodetic coordinates at the SK center were obtained to be Lat. 36 25'32.5862'' N., Long. 137 18'37.1241'' E., H. 371.839 m in the global ellipsoidal coordinate system, WGS-84. The obtained coordinates are based on the coordinates given at a triangulation point at the KEK site. The present work will be fed back for constructing the neutrino beam line. (orig.)

Public green spaces and positive mental health - investigating the relationship between access, quantity and types of parks and mental wellbeing.

Science.gov (United States)

Wood, Lisa; Hooper, Paula; Foster, Sarah; Bull, Fiona

2017-11-01

Associations between parks and mental health have typically been investigated in relation to the presence or absence of mental illness. This study uses a validated measure of positive mental health and data from RESIDential Environments (RESIDE) Project to investigate the association between the presence, amount and attributes of public green space in new greenfield neighbourhood developments and the mental health of local residents (n = 492). Both the overall number and total area of public green spaces were significantly associated with greater mental wellbeing, and findings support a dose-response relationship. Positive mental health was not only associated with parks with a nature focus, but also with green spaces characterised by recreational and sporting activity. The study demonstrates that adequate provision of public green space in local neighbourhoods and within walking distance is important for positive mental health. Copyright © 2017. Published by Elsevier Ltd.

Robust independent modal space control of a coupled nano-positioning piezo-stage

Science.gov (United States)

Zhu, Wei; Yang, Fufeng; Rui, Xiaoting

2018-06-01

In order to accurately control a coupled 3-DOF nano-positioning piezo-stage, this paper designs a hybrid controller. In this controller, a hysteresis observer based on a Bouc-Wen model is established to compensate the hysteresis nonlinearity of the piezoelectric actuator first. Compared to hysteresis compensations using Preisach model and Prandt-Ishlinskii model, the compensation method using the hysteresis observer is computationally lighter. Then, based on the proposed dynamics model, by constructing the modal filter, a robust H∞ independent modal space controller is designed and utilized to decouple the piezo-stage and deal with the unmodeled dynamics, disturbance, and hysteresis compensation error. The effectiveness of the proposed controller is demonstrated experimentally. The experimental results show that the proposed controller can significantly achieve the high-precision positioning.

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

Science.gov (United States)

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.

Monitoring jonosfere i svemirskog vremena u Bosni i Hercegovini : Monitoring of ionosphere and space weather in Bosnia and Herzegovina

Directory of Open Access Journals (Sweden)

Džana Horozović

2015-12-01

Full Text Available Zbog svoje disperzivne prirode, jonosfera uzrokuje kašnjenje koda, odnosno ubrzanje faze signala Globalnih navigacijskih satelitskih sistema - GNSS. Usprkos napretku metoda GNSS pozicioniranja, jonosferska refrakcija je još uvijek jedan od najvećih izvora pogrešaka geodetskog pozicioniranja i navigacije. Različiti fenomeni svemirskog vremena, kao: solarni vjetar, geomagnetna oluja, solarna radijacija, može oštetiti GNSS satelite, dalekovode i elektrodistributivnu mrežu, itd. Zato je važno ustanoviti metode istraživanja i monitoringa svemirskog vremena. Istraživanje jonosfere i svemirskog vremena je predmet ovog rada. Opisan je postupak konstruiranja SID (engl. sudden ionospheric disturbances – iznenadne jonosferske smetnje monitora. Analiza je pokazala da je jonosferska monitoring stanica u Sarajevu SRJV_ION 0436 sposobna otkriti pojačano zračenje. : Due to its dispersive nature, ionosphere causes a group delay or phase acceleration of the signals from Global navigation satellite systems - GNSS. Despite the progress of GNSS positioning methods, the ionospheric refraction is still one of the greatest source of the errors in the geodetic positioning and navigation. Different phenomenons oft he space weather: solar wind, geomagnetic storm, solar radiation, can damage GNSS, and electric power distribution networks but That is why it's important to establish research and monitoring methods of the space weather. The subject of this paper is the investigation of ionosphere and space weather. Procedure of constructing a SID (engl. Sudden ionospheric disturbances monitor station are described. The analysis showed that ionosphere monitoring station in Sarajevo, SRJV_ION 0436, was able to detect increased solar radiation.

MIVIS image geocoding experience on merging position attitude system data and public domain GPS stream (ASI-GeoDAF

Directory of Open Access Journals (Sweden)

S. Pignatti

2006-06-01

Full Text Available The use of airborne scanners involves geo-referencing problems, which are difficult because of the need to know the exact platform position and attitude for each scan line. The errors of the onboard navigation system are normally corrected using ground control point on the image. This post-processing correction procedure is too long in case of multiple flight campaigns, and besides it implies the need to have available 1:10000 orthophotoimages or maps in digital format. To optimize the above procedure a new method to correct MIVIS navigational data in the post-processing phase has been implemented. The procedure takes into consideration the GPS stream in Rinex format of common knowledge and findable on the web, acquired at the ground stations of the Geodetic Data Archiving Facilities provided by ASI. The application of this correction entails the assumption that the environmental variables affecting both onboard and geodetic GPS equally affect the position measurements. The airborne data correction was carried out merging the two data sets (onboard and ground station GPS to achieve a more precise aircraft trajectory. The present study compares the geo-coded images obtained by means of the two post-processing methods.

Three-point Green's function of massless QED in position space to lowest order

International Nuclear Information System (INIS)

Mitra, Indrajit

2009-01-01

The transverse part of the three-point Green's function of massless QED is determined to the lowest order in position space. Taken together with the evaluation of the longitudinal part in Mitra (2008) (J. Phys. A: Math. Theor. 41 315401), this gives a relation for QED which is analogous to the star-triangle relation. We relate our result to conformal-invariant three-point functions

Geodetic slip solutions for the Mw = 7.4 Champerico (Guatemala) earthquake of 2012 November 7 and its postseismic deformation

Science.gov (United States)

Ellis, Andria P.; DeMets, Charles; Briole, Pierre; Molina, Enrique; Flores, Omar; Rivera, Jeffrey; Lasserre, Cécile; Lyon-Caen, Hélène; Lord, Neal

2015-05-01

As the first large subduction thrust earthquake off the coast of western Guatemala in the past several decades, the 2012 November 7 Mw = 7.4 earthquake offers the first opportunity to study coseismic and postseismic behaviour along a segment of the Middle America trench where frictional coupling makes a transition from weak coupling off the coast of El Salvador to strong coupling in southern Mexico. We use measurements at 19 continuous GPS sites in Guatemala, El Salvador and Mexico to estimate the coseismic slip and postseismic deformation of the November 2012 Champerico (Guatemala) earthquake. An inversion of the coseismic offsets, which range up to ˜47 mm at the surface near the epicentre, indicates that up to ˜2 m of coseismic slip occurred on a ˜30 × 30 km rupture area between ˜10 and 30 km depth, which is near the global CMT centroid. The geodetic moment of 13 × 1019 N m and corresponding magnitude of 7.4 both agree well with independent seismological estimates. Transient postseismic deformation that was recorded at 11 GPS sites is attributable to a combination of fault afterslip and viscoelastic flow in the lower crust and/or mantle. Modelling of the viscoelastic deformation suggests that it constituted no more than ˜30 per cent of the short-term postseismic deformation. GPS observations that extend six months after the earthquake are well fit by a model in which most afterslip occurred at the same depth or directly downdip from the rupture zone and released energy equivalent to no more than ˜20 per cent of the coseismic moment. An independent seismological slip solution that features more highly concentrated coseismic slip than our own fits the GPS offsets well if its slip centroid is translated ˜50 km to the west to a position close to our slip centroid. The geodetic and seismologic slip solutions thus suggest bounds of 2-7 m for the peak slip along a region of the interface no larger than 30 × 30 km.

Analysis of ILRS Site Ties

Science.gov (United States)

Husson, V. S.; Long, J. L.; Pearlman, M.

2001-12-01

By the end of 2000, 94% of ILRS stations had completed station and site information forms (i.e. site logs). These forms contain six types of information. These six categories include site identifiers, contact information, approximate coordinates, system configuration history, system ranging capabilities, and local survey ties. The ILRS Central Bureau, in conjunction with the ILRS Networks and Engineering Working Group, has developed procedures to quality control site log contents. Part of this verification entails data integrity checks of local site ties and is the primary focus of this paper. Local survey ties are critical to the combination of space geodetic network coordinate solutions (i.e. GPS, SLR, VLBI, DORIS) of the International Terrestrial Reference Frame (ITRF). Approximately 90% of active SLR sites are collocated with at least one other space geodetic technique. The process used to verify these SLR ties, at collocated sites, is identical to the approach used in ITRF2000. Local vectors (X, Y, Z) from each ILRS site log are differenced from its corresponding ITRF2000 position vectors (i.e. no transformations). These X, Y, and Z deltas are converted into North, East, and Up. Any deltas, in any component, larger than 5 millimeter is flagged for investigation. In the absence of ITRF2000 SLR positions, CSR positions were used. To further enhance this comparison and to fill gaps in information, local ties contained in site logs from the other space geodetic services (i.e. IGS, IVS, IDS) were used in addition to ITRF2000 ties. Case studies of two collocated sites (McDonald/Ft. Davis and Hartebeeshtoek) will be explored in-depth. Recommendations on how local site surveys should be conducted and how this information should be managed will also be presented.

Geodetic constraints on continental rifting along the Red Sea

Science.gov (United States)

Reilinger, R.; McClusky, S.; Arrajehi, A.; Mahmoud, S.; Rayan, A.; Ghebreab, W.; Ogubazghi, G.; Al-Aydrus, A.

2006-12-01

We are using the Global Positioning System (GPS) to monitor and quantify patterns and rates of tectonic and magmatic deformation associated with active rifting of the continental lithosphere and the transition to sea floor spreading in the Red Sea. Broad-scale motions of the Nubian and Arabian plates indicate coherent plate motion with internal deformation below the current resolution of our measurements (~ 1-2 mm/yr). The GPS-determined Euler vector for Arabia-Nubia is indistinguishable from the geologic Euler vector determined from marine magnetic anomalies, and Arabia-Eurasia relative motion from GPS is equal within uncertainties to relative motion determined from plate reconstructions, suggesting that Arabia plate motion has remained constant (±10%) during at least the past ~10 Ma. The approximate agreement between broad-scale GPS rates of extension (i.e., determined from relative plate motions) and those determined from magnetic anomalies along the Red Sea rift implies that spreading in the central Red Sea is primarily confined to the central rift (±10-20%). Extension appears to be more broadly distributed in the N Red Sea and Gulf of Suez where comparisons with geologic data also indicate a relatively recent (between 500 and 125 kyr BP) change in the motion of the Sinai block that is distinct from both Nubia and Arabia. In the southern Red Sea, GPS results are beginning to define the motion of the "Danakil micro-plate". We investigate and report on a model involving CCW rotation of the Danakil micro-plate relative to Nubia and magmatic inflation below the Afar Triple Junction that is consistent with available geodetic constraints. Running the model back in time suggests that the Danakil micro-plate has been an integral part of rifting/triple junction processes throughout the history of separation of the Arabian and Nubian plates. On the scale of Nubia-Arabia-Eurasia plate interactions, we show that new area formed at spreading centers roughly equals that

Implementing a C++ Version of the Joint Seismic-Geodetic Algorithm for Finite-Fault Detection and Slip Inversion for Earthquake Early Warning

Science.gov (United States)

Smith, D. E.; Felizardo, C.; Minson, S. E.; Boese, M.; Langbein, J. O.; Guillemot, C.; Murray, J. R.

2015-12-01

The earthquake early warning (EEW) systems in California and elsewhere can greatly benefit from algorithms that generate estimates of finite-fault parameters. These estimates could significantly improve real-time shaking calculations and yield important information for immediate disaster response. Minson et al. (2015) determined that combining FinDer's seismic-based algorithm (Böse et al., 2012) with BEFORES' geodetic-based algorithm (Minson et al., 2014) yields a more robust and informative joint solution than using either algorithm alone. FinDer examines the distribution of peak ground accelerations from seismic stations and determines the best finite-fault extent and strike from template matching. BEFORES employs a Bayesian framework to search for the best slip inversion over all possible fault geometries in terms of strike and dip. Using FinDer and BEFORES together generates estimates of finite-fault extent, strike, dip, preferred slip, and magnitude. To yield the quickest, most flexible, and open-source version of the joint algorithm, we translated BEFORES and FinDer from Matlab into C++. We are now developing a C++ Application Protocol Interface for these two algorithms to be connected to the seismic and geodetic data flowing from the EEW system. The interface that is being developed will also enable communication between the two algorithms to generate the joint solution of finite-fault parameters. Once this interface is developed and implemented, the next step will be to run test seismic and geodetic data through the system via the Earthworm module, Tank Player. This will allow us to examine algorithm performance on simulated data and past real events.

Green Schoolyards in Low-Income Urban Neighborhoods: Natural Spaces for Positive Youth Development Outcomes

Directory of Open Access Journals (Sweden)

Carolyn R. Bates

2018-05-01

Full Text Available Children from low-income families are increasingly growing up in urban areas with limited access to nature. In these environments, strategies that promote access to natural outdoor spaces, such as green schoolyards, may enhance positive youth development outcomes by promoting physical activity (PA and prosocial behavior, as well as increasing perceptions of safety. The current study examines children’s PA and social interactions, as well as caregiver and teacher perceptions of safety, injuries, teasing/bullying, and gang activity on three newly renovated green schoolyards in low-income urban neighborhoods. A multi-method strategy, including behavioral mapping and caregiver- and teacher-reported surveys, was utilized at three time points to examine positive youth development outcomes and maintenance of effects over time. Analyses revealed that children evidenced a range of PA on the green schoolyards and demonstrated significant decreases in sedentary activity over time. The majority of children were engaged in social interactions with peers on the green schoolyards when observed. Less than 3% of interactions were negative and follow-up analyses found significant increases in positive interactions on the green schoolyards up to 24 months post-renovation. Caregivers and teachers reported increased perceptions of safety, fewer injuries, less teasing/bullying, and less gang-related activity on the renovated green schoolyards in comparison to the pre-renovation schoolyards, and these effects were maintained up to 32 months post-renovation. Overall, the study suggests that green schoolyards may promote positive development outcomes among youth living in urban, low-income neighborhoods by providing natural and safe spaces for PA and prosocial behavior.

Displaced squeezed number states: Position space representation, inner product, and some applications

DEFF Research Database (Denmark)

Møller, Klaus Braagaard; Jørgensen, Thomas Godsk; Dahl, Jens Peder

1996-01-01

For some applications the overall phase of a quantum state is crucial. For the so-called displaced squeezed number state (DSN), which is a generalization of the well-known squeezed coherent state, we obtain the position space representation with the correct overall phase, from the dynamics...... in a harmonic potential. The importance of the overall phase is demonstrated in the context of characteristic or moment generating functions. For two special cases the characteristic function is shown to be computable from the inner product of two different DSNs....

Precise GNSS Positioning Using Smart Devices

Directory of Open Access Journals (Sweden)

Eugenio Realini

2017-10-01

Full Text Available The recent access to GNSS (Global Navigation Satellite System phase observations on smart devices, enabled by Google through its Android operating system, opens the possibility to apply precise positioning techniques using off-the-shelf, mass-market devices. The target of this work is to evaluate whether this is feasible, and which positioning accuracy can be achieved by relative positioning of the smart device with respect to a base station. Positioning of a Google/HTC Nexus 9 tablet was performed by means of batch least-squares adjustment of L1 phase double-differenced observations, using the open source goGPS software, over baselines ranging from approximately 10 m to 8 km, with respect to both physical (geodetic or low-cost and virtual base stations. The same positioning procedure was applied also to a co-located u-blox low-cost receiver, to compare the performance between the receiver and antenna embedded in the Nexus 9 and a standard low-cost single-frequency receiver with external patch antenna. The results demonstrate that with a smart device providing raw GNSS phase observations, like the Nexus 9, it is possible to reach decimeter-level accuracy through rapid-static surveys, without phase ambiguity resolution. It is expected that sub-centimeter accuracy could be achieved, as demonstrated for the u-blox case, if integer phase ambiguities were correctly resolved.

Precise GNSS Positioning Using Smart Devices.

Science.gov (United States)

Realini, Eugenio; Caldera, Stefano; Pertusini, Lisa; Sampietro, Daniele

2017-10-24

The recent access to GNSS (Global Navigation Satellite System) phase observations on smart devices, enabled by Google through its Android operating system, opens the possibility to apply precise positioning techniques using off-the-shelf, mass-market devices. The target of this work is to evaluate whether this is feasible, and which positioning accuracy can be achieved by relative positioning of the smart device with respect to a base station. Positioning of a Google/HTC Nexus 9 tablet was performed by means of batch least-squares adjustment of L1 phase double-differenced observations, using the open source goGPS software, over baselines ranging from approximately 10 m to 8 km, with respect to both physical (geodetic or low-cost) and virtual base stations. The same positioning procedure was applied also to a co-located u-blox low-cost receiver, to compare the performance between the receiver and antenna embedded in the Nexus 9 and a standard low-cost single-frequency receiver with external patch antenna. The results demonstrate that with a smart device providing raw GNSS phase observations, like the Nexus 9, it is possible to reach decimeter-level accuracy through rapid-static surveys, without phase ambiguity resolution. It is expected that sub-centimeter accuracy could be achieved, as demonstrated for the u-blox case, if integer phase ambiguities were correctly resolved.

On a possibility of creation of positive space charge cloud in a system with magnetic insulation of electrons

International Nuclear Information System (INIS)

Goncharov, A.A.; Dobrovol'skii, A.M.; Dunets, S.P.; Evsyukov, A.N.; Protsenko, I.M.

2009-01-01

We describe a new approach for creation an effective, low-cost, low-maintenance axially symmetric plasma optical tools for focusing and manipulating high-current beams of negatively charged particles, electrons and negative ions. This approach is based on fundamental plasma optical concept of magnetic insulation of electrons and non-magnetized positive ions providing creation of controlled uncompensated cloud of the space charge. The axially symmetric electrostatic plasma optical lens is well-known and well developed tool where this concept is used successfully. This provides control and focusing high-current positive ion beams in wide range of parameters. Here for the first time we present optimistic experimental results describing the application of an idea of magnetic insulation of electrons for generation of the stable cloud of positive space charge by focusing onto axis the converging stream of heavy ions produced by circular accelerator with closed electron drift. The estimations of a maximal concentration of uncompensated cloud of positive ions are also made

Positioning Reduction of Deep Space Probes Based on VLBI Tracking

Science.gov (United States)

Qiao, S. B.

2011-11-01

) Investigate the application of Kalman filter to the positioning reduction of deep space probes and develop related software systems. In summary, the progress in this dissertation is made in the positioning reduction of deep space probes tracked by VLBI concerning the algorithm study, software development, real observation processing and so on, while a further study is still urgent and arduous.

Polarised Multiangular Reflectance Measurements Using the Finnish Geodetic Institute Field Goniospectrometer

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Jouni Peltoniemi

2009-05-01

Full Text Available The design, operation, and properties of the Finnish Geodetic Institute Field Goniospectrometer (FIGIFIGO are presented. FIGIFIGO is a portable instrument for the measurement of surface Bidirectional Reflectance Factor (BRF for samples with diameters of 10 – 50 cm. A set of polarising optics enable the measurement of linearly polarised BRF over the full solar spectrum (350 – 2,500 nm. FIGIFIGO is designed mainly for field operation using sunlight, but operation in a laboratory environment is also possible. The acquired BRF have an accuracy of 1 – 5% depending on wavelength, sample properties, and measurement conditions. The angles are registered at accuracies better than 2°. During 2004 – 2008, FIGIFIGO has been used in the measurement of over 150 samples, all around northern Europe. The samples concentrate mostly on boreal forest understorey, snow, urban surfaces, and reflectance calibration surfaces.

Positioning in a flat two-dimensional space-time: The delay master equation

International Nuclear Information System (INIS)

Coll, Bartolome; Ferrando, Joan Josep; Morales-Lladosa, Juan Antonio

2010-01-01

The basic theory on relativistic positioning systems in a two-dimensional space-time has been presented in two previous papers [B. Coll, J. J. Ferrando, and J. A. Morales, Phys. Rev. D 73, 084017 (2006); ibid.74, 104003 (2006)], where the possibility of making relativistic gravimetry with these systems has been analyzed by considering specific examples. Here, generic relativistic positioning systems in the Minkowski plane are studied. The information that can be obtained from the data received by a user of the positioning system is analyzed in detail. In particular, it is shown that the accelerations of the emitters and of the user along their trajectories are determined by the sole knowledge of the emitter positioning data and of the acceleration of only one of the emitters. Moreover, as a consequence of the so-called master delay equation, the knowledge of this acceleration is only required during an echo interval, i.e., the interval between the emission time of a signal by an emitter and its reception time after being reflected by the other emitter. These results are illustrated with the obtention of the dynamics of the emitters and of the user from specific sets of data received by the user.

Asymptotic structure of space-time with a positive cosmological constant

Science.gov (United States)

Kesavan, Aruna

In general relativity a satisfactory framework for describing isolated systems exists when the cosmological constant Lambda is zero. The detailed analysis of the asymptotic structure of the gravitational field, which constitutes the framework of asymptotic flatness, lays the foundation for research in diverse areas in gravitational science. However, the framework is incomplete in two respects. First, asymptotic flatness provides well-defined expressions for physical observables such as energy and momentum as 'charges' of asymptotic symmetries at null infinity, [special character omitted] +. But the asymptotic symmetry group, called the Bondi-Metzner-Sachs group is infinite-dimensional and a tensorial expression for the 'charge' integral of an arbitrary BMS element is missing. We address this issue by providing a charge formula which is a 2-sphere integral over fields local to the 2-sphere and refers to no extraneous structure. The second, and more significant shortcoming is that observations have established that Lambda is not zero but positive in our universe. Can the framework describing isolated systems and their gravitational radiation be extended to incorporate this fact? In this dissertation we show that, unfortunately, the standard framework does not extend from the Lambda = 0 case to the Lambda > 0 case in a physically useful manner. In particular, we do not have an invariant notion of gravitational waves in the non-linear regime, nor an analog of the Bondi 'news tensor', nor positive energy theorems. In addition, we argue that the stronger boundary condition of conformal flatness of intrinsic metric on [special character omitted]+, which reduces the asymptotic symmetry group from Diff([special character omitted]) to the de Sitter group, is insufficient to characterize gravitational fluxes and is physically unreasonable. To obtain guidance for the full non-linear theory with Lambda > 0, linearized gravitational waves in de Sitter space-time are analyzed in

Monitoring ground deformation of cultural heritage sites using UAVs and geodetic techniques: the case study of Choirokoitia, JPI PROTHEGO project

Science.gov (United States)

Themistocleous, Kyriacos; Danezis, Chris; Mendonidis, Evangelos; Lymperopoulou, Efstathia

2017-10-01

This paper presents the integrated methods using UAVs and geodetic techniques to monitor ground deformation within the Choirokoitia UNESCO World Heritage Site in Cyprus. The Neolithic settlement of Choirokoitia, occupied from the 7th to the 4th millennium B.C., is one of the most important prehistoric sites in the eastern Mediterranean. The study is conducted under the PROTHEGO (PROTection of European Cultural HEritage from GeO-hazards) project, which is a collaborative research project funded in the framework of the Joint Programming Initiative on Cultural Heritage and Global Change (JPICH) - Heritage Plus in 2015-2018 (www.prothego.eu) and through the Cyprus Research Promotion Foundation. PROTHEGO aims to make an innovative contribution towards the analysis of geo-hazards in areas of cultural heritage, and uses novel space technology based on radar interferometry to retrieve information on ground stability and motion in the 400+ UNESCO's World Heritage List monuments and sites of Europe. The field measurements collected at the Choirokoitia site will be later compared with SAR data to verify micro-movements in the area to monitor potential geo-hazards. The site is located on a steep hill, which makes it vulnerable to rock falls and landslides.

Design considerations for an astronaut monorail system for large space structures and the structural characterization of its positioning arm

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Watson, Judith J.

1992-08-01

An astronaut monorail system (AMS) is presented as a vehicle to transport and position EVA astronauts along large space truss structures. The AMS is proposed specifically as an alternative to the crew and equipment transfer aid for Space Station Freedom. Design considerations for the AMS were discussed and a reference configuration was selected for the study. Equations were developed to characterize the stiffness and frequency behavior of the AMS positioning arm. Experimental data showed that these equations gave a fairly accurate representation of the stiffness and frequency behavior of the arm. A study was presented to show trends for the arm behavior based on varying parameters of the stiffness and frequency equations. An ergonomics study was conducted to provide boundary conditions for tolerable frequency and deflection to be used in developing a design concept for the positioning arm. The feasibility of the AMS positioning arm was examined using equations and working curves developed in this study. It was found that a positioning arm of a length to reach all interior points of the space station truss structure could not be designed to satisfy frequency and deflection constraints. By relaxing the design requirements and the ergonomic boundaries, an arm could be designed which would provide a stable work platform for the EVA astronaut and give him access to over 75 percent of the truss interior.

Establishing a Modern Ground Network for Space Geodesy Applications

Science.gov (United States)

Pearlman, M.; Pavlis, E.; Altamimi, Z.; Noll, C.

2010-01-01

Ground-based networks of co-located space-geodesy techniques (VLBI, SLR, GLASS, DORIS) are the basis for the development and maintenance of the :International Terrestrial deference Frame (ITRE), which is the basis for our metric measurements of global change. The Global Geodetic Observing System (GGOS) within the International Association of Geodesy has established a task to develop a strategy to design, integrate and maintain the fundamental geodetic network and supporting infrastructure in a sustainable way to satisfy the long-term requirements for the reference frame. The GGOS goal is an origin definition at I mm or better and a temporal stability on the order of 0.1 mm/y, with similar numbers for the scale and orientation components. These goals are based on scientific requirements to address sea level rise with confidence. As a first step, simulations focused on establishing the optimal global SLR and VLBI network, since these two techniques alone are sufficient to define the reference frame. The GLASS constellations will then distribute the reference frame to users anywhere on the Earth. Using simulated data to be collected by the future networks, we investigated various designs and the resulting accuracy in the origin, scale and orientation of the resulting ITRF. We present here the results of extensive simulation studies aimed at designing optimal global geodetic networks to support GGOS science products. Current estimates are the network will require 24 - 32 globally distributed co-location sites. Stations in the near global network will require geologically stable sites witla good weather, established infrastructure, and local support and personnel. EGOS will seek groups that are interested in participation. GGOS intends to issues a Call for Participation of groups that would like to take part in the network implementation and operation_ Some examples of integrated stations currently in operation or under development will be presented. We will examine

An Approach for High-precision Stand-alone Positioning in a Dynamic Environment

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Halis Saka, M.; Metin Alkan, Reha; Ozpercin, Alişir

2015-04-01

In this study, an algorithm is developed for precise positioning in dynamic environment utilizing a single geodetic GNSS receiver using carrier phase data. In this method, users should start the measurement on a known point near the project area for a couple of seconds making use of a single dual-frequency geodetic-grade receiver. The technique employs iono-free carrier phase observations with precise products. The equation of the algorithm is given below; Sm(t(i+1))=SC(ti)+[ΦIF (t(i+1) )-ΦIF (ti)] where, Sm(t(i+1)) is the phase-range between satellites and the receiver, SC(ti) is the initial range computed from the initial known point coordinates and the satellite coordinates and ΦIF is the ionosphere-free phase measurement (in meters). Tropospheric path delays are modelled using the standard tropospheric model. To accomplish the process, an in-house program was coded and some functions were adopted from Easy-Suite available at http://kom.aau.dk/~borre/easy. In order to assess the performance of the introduced algorithm in a dynamic environment, a dataset from a kinematic test measurement was used. The data were collected from a kinematic test measurement in Istanbul, Turkey. In the test measurement, a geodetic dual-frequency GNSS receiver, Ashtech Z-Xtreme, was set up on a known point on the shore and a couple of epochs were recorded for initialization. The receiver was then moved to a vessel and data were collected for approximately 2.5 hours and the measurement was finalized on a known point on the shore. While the kinematic measurement on the vessel were carried out, another GNSS receiver was set up on a geodetic point with known coordinates on the shore and data were collected in static mode to calculate the reference trajectory of the vessel using differential technique. The coordinates of the vessel were calculated for each measurement epoch with the introduced method. With the purpose of obtaining more robust results, all coordinates were calculated

Geodetic Measurements and Numerical Modeling of the Deformation Cycle for Okmok Volcano, Alaska: 1993-2008

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Ohlendorf, S. J.; Feigl, K.; Thurber, C. H.; Lu, Z.; Masterlark, T.

2011-12-01

Okmok Volcano is an active caldera located on Umnak Island in the Aleutian Island arc. Okmok, having recently erupted in 1997 and 2008, is well suited for multidisciplinary studies of magma migration and storage because it hosts a good seismic network and has been the subject of synthetic aperture radar (SAR) images that span the recent eruption cycle. Interferometric SAR can characterize surface deformation in space and time, while data from the seismic network provides important information about the interior processes and structure of the volcano. We conduct a complete time series analysis of deformation of Okmok with images collected by the ERS and Envisat satellites on more than 100 distinct epochs between 1993 and 2008. We look for changes in inter-eruption inflation rates, which may indicate inelastic rheologic effects. For the time series analysis, we analyze the gradient of phase directly, without unwrapping, using the General Inversion of Phase Technique (GIPhT) [Feigl and Thurber, 2009]. This approach accounts for orbital and atmospheric effects and provides realistic estimates of the uncertainties of the model parameters. We consider several models for the source, including the prolate spheroid model and the Mogi model, to explain the observed deformation. Using a medium that is a homogeneous half space, we estimate the source depth to be centered at about 4 km below sea level, consistent with the findings of Masterlark et al. [2010]. As in several other geodetic studies, we find the source to be approximately centered beneath the caldera. To account for rheologic complexity, we next apply the Finite Element Method to simulate a pressurized cavity embedded in a medium with material properties derived from body wave seismic tomography. This approach allows us to address the problem of unreasonably large pressure values implied by a Mogi source with a radius of about 1 km by experimenting with larger sources. We also compare the time dependence of the

Discoveries and Controversies in Geodetic Imaging of Deformation Before and After the M=9 Tohoku-oki Earthquake

Science.gov (United States)

Wang, K.; Sun, T.; Hino, R.; Iinuma, T.; Tomita, F.; Kido, M.

2017-12-01

Numerous observations pertaining to the M=9.0 2011 Tohoku-oki earthquake have led to new understanding of subduction zone earthquakes. By synthesizing published research results and our own findings, we explore what has been learned about fault behavior and Earth rheology from geodetic imaging of crustal deformation before and after the earthquake. Before the earthquake, megathrust locking models based on land-based geodetic observations correctly outlined the along-strike location of the future rupture zone, showing that land-based observations are capable of resolving along-strike variations in locking and creep at wavelengths comparable to distances from the network. But they predicted a locked zone that was much deeper than the actual rupture in 2011. The incorrect definition of the locking pattern in the dip direction demonstrates not only the need for seafloor geodesy but also the importance of modeling interseismic viscoelastic stress relaxation and stress shadowing. The discovery of decade-long accelerated slip downdip of the future rupture zone raises new questions on fault mechanics. After the earthquake, seafloor geodetic discovery of opposing motion offshore provided unambiguous evidence for the dominance of viscoelastic relaxation in short-term postseismic deformation. There is little deep afterslip in the fault area where the decade-long pre-earthquake slip acceleration is observed. The complementary spatial distribution of pre-slip and afterslip calls for new scientific research. However, the near absence of deep afterslip directly downdip of the main rupture is perceived to be controversial because some viscoelastic models do predict large afterslip here, although less than predicted by purely elastic models. We show that the large afterslip in these models is largely an artefact due to the use of a layered Earth model without a subducting slab. The slab acts as an "anchor" in the mantle and retards landward motion following a subduction earthquake

Undergraduate teaching modules featuring geodesy data applied to critical social topics (GETSI: GEodetic Tools for Societal Issues)

Science.gov (United States)

Pratt-Sitaula, B. A.; Walker, B.; Douglas, B. J.; Charlevoix, D. J.; Miller, M. M.

2015-12-01

The GETSI project, funded by NSF TUES, is developing and disseminating teaching and learning materials that feature geodesy data applied to critical societal issues such as climate change, water resource management, and natural hazards (serc.carleton.edu/getsi). It is collaborative between UNAVCO (NSF's geodetic facility), Mt San Antonio College, and Indiana University. GETSI was initiated after requests by geoscience faculty for geodetic teaching resources for introductory and majors-level students. Full modules take two weeks but module subsets can also be used. Modules are developed and tested by two co-authors and also tested in a third classroom. GETSI is working in partnership with the Science Education Resource Center's (SERC) InTeGrate project on the development, assessment, and dissemination to ensure compatibility with the growing number of resources for geoscience education. Two GETSI modules are being published in October 2015. "Ice mass and sea level changes" includes geodetic data from GRACE, satellite altimetry, and GPS time series. "Imaging Active Tectonics" has students analyzing InSAR and LiDAR data to assess infrastructure earthquake vulnerability. Another three modules are in testing during fall 2015 and will be published in 2016. "Surface process hazards" investigates mass wasting hazard and risk using LiDAR data. "Water resources and geodesy" uses GRACE, vertical GPS, and reflection GPS data to have students investigating droughts in California and the High Great Plains. "GPS, strain, and earthquakes" helps students learn about infinitesimal and coseismic strain through analysis of horizontal GPS data and includes an extension module on the Napa 2014 earthquake. In addition to teaching resources, the GETSI project is compiling recommendations on successful development of geodesy curricula. The chief recommendations so far are the critical importance of including scientific experts in the authorship team and investing significant resources in

The RMI Space Weather and Navigation Systems (SWANS) Project

Science.gov (United States)

Warnant, Rene; Lejeune, Sandrine; Wautelet, Gilles; Spits, Justine; Stegen, Koen; Stankov, Stan

precision for several GPS stations in Belgium. The service assesses the effect of small-scale ionospheric irregularities by monitoring the high-frequency TEC rate of change at any given station. This assessment results in a (colour) code assigned to each station, code ranging from "quiet" (green) to "extreme" (red) and referring to the local ionospheric conditions. Alerts via e-mail are sent to subscribed users when disturbed conditions are observed. SoDIPE (Software for Determining the Ionospheric Positioning Error) estimates the position-ing error due to the ionospheric conditions only (called "ionospheric error") in high-precision positioning applications (RTK in particular). For each of the Belgian Active Geodetic Network (AGN) baselines, SoDIPE computes the ionospheric error and its median value (every 15 min-utes). Again, a (colour) code is assigned to each baseline, ranging from "nominal" (green) to "extreme" (red) error level. Finally, all available baselines (drawn in colour corresponding to error level) are displayed on a map of Belgium. The future SWANS work will focus on regional ionospheric monitoring and developing various other nowcast and forecast services.

THE ROLE OF ASTRO-GEODETIC IN PRECISE GUIDANCE OF LONG TUNNELS

Directory of Open Access Journals (Sweden)

M. Mirghasempour

2015-12-01

Full Text Available One of prime aspects of surveying projects is guidance of paths of a long tunnel from different directions and finally ending all paths in a specific place. This kind of underground surveying, because of particular condition, has some different points in relation to the ground surveying, including Improper geometry in underground transverse, low precise measurement in direction and length due to condition such as refraction, distinct gravity between underground point and corresponding point on the ground (both value and direction of gravity and etc. To solve this problems, astro-geodetic that is part of geodesy science, can help surveying engineers. In this article, the role of astronomy is defined in two subjects: 1- Azimuth determination of directions from entrance and exit nets of tunnel and also calibration of gyro-theodolite to use them in Underground transvers: By astronomical methods, azimuth of directions can be determine with an accuracy of 0.5 arcsecond, whereas, nowadays, no gyroscope can measure the azimuth in this accuracy; For instance, accuracy of the most precise gyroscope (Gyromat 5000 is 1.2 cm over a distance of one kilometre (2.4 arcsecond. Furthermore, the calibration methods that will be mention in this article, have significance effects on underground transverse. 2- Height relation between entrance point and exit point is problematic and time consuming; For example, in a 3 km long tunnel ( in Arak- Khoram Abad freeway, to relate entrance point to exit point, it is necessary to perform levelling about 90 km. Other example of this boring and time consuming levelling is in Kerman tunnel. This tunnel is 36 km length, but to transfer the entrance point height to exit point, 150 km levelling is needed. According to this paper, The solution for this difficulty is application of astro-geodetic and determination of vertical deflection by digital zenith camera system TZK2-D. These two elements make possible to define geoid profile

UNAVCO Geodetic HIgh-Rate and Real-Time Products and Services: A next generation geodetic network

Science.gov (United States)

Mattioli, G. S.; Mencin, D.; Meertens, C. M.; Feaux, K.; Looney, S.

2012-12-01

Recent advances in GPS technology and data processing are providing position estimates with centimeter-level precision at high-rate (1 Hz) and low latency (transforming rapid event characterization, early warning, as well as hazard mitigation and response. Other scientific and operational applications for high-rate GPS also include glacier and ice sheet motions, tropospheric modeling, and better constraints on the dynamics of space weather. UNAVCO, through community input and the recent Plate Boundary Observatory (PBO) NSF-ARRA Cascadia initiative, has nearly completed the process of upgrading a total of 373 PBO GPS sites to real-time high-rate capability and these streams are now being archived in our data center. In addition, UNAVCO hosted an NSF funded workshop in Boulder, CO on March 26-28, which brought together 70 participants representing a spectrum of research fields with a goal to develop a community plan for the use of real-time GPS data products within the UNAVCO and EarthScope communities. These data products are expected to improve and expand the use of real-time GPS data over the next decade. Additionally, in collaboration with NOAA, 74 of these stations will provide meteorological data in real-time, primarily to support watershed and flood analyses for regional early-warning systems related to NOAA's work with California Department of Water Resources. As part of this upgrade UNAVCO is also exploring making the 75 PBO borehole strainmeter sites, whose data are now collected with a latency of 24 hours, available in SEED format in real-time in the near future, providing an opportunity to combine high-rate surface positioning and strain data together.

The potential role of real-time geodetic observations in tsunami early warning

Science.gov (United States)

Tinti, Stefano; Armigliato, Alberto

2016-04-01

experimental or testing stage and haven't been implemented yet in any standard TWS operations. Nonetheless, this is seen to be the future and the natural TWS evolving enhancement. In this context, improvement of the real-time estimates of tsunamigenic earthquake focal mechanism is of fundamental importance to trigger the appropriate computational chain. Quick discrimination between strike-slip and thrust-fault earthquakes, and equally relevant, quick assessment of co-seismic on-fault slip distribution, are exemplary cases to which a real-time geodetic monitoring system can contribute significantly. Robust inversion of geodetic data can help to reconstruct the sea floor deformation pattern especially if two conditions are met: the source is not too far from network stations and is well covered azimuthally. These two conditions are sometimes hard to satisfy fully, but in certain regions, like the Mediterranean and the Caribbean sea, this is quite possible due to the limited size of the ocean basins. Close cooperation between the Global Geodetic Observing System (GGOS) community, seismologists, tsunami scientists and TWS operators is highly recommended to obtain significant progresses in the quick determination of the earthquake source, which can trigger a timely estimation of the ensuing tsunami and a more reliable and detailed assessment of the tsunami size at the coast.

Serial position markers in space: visuospatial priming of serial order working memory retrieval.

Directory of Open Access Journals (Sweden)

Maya De Belder

Full Text Available Most general theories on serial order working memory (WM assume the existence of position markers that are bound to the to-be-remembered items to keep track of the serial order. So far, the exact cognitive/neural characteristics of these markers have remained largely underspecified, while direct empirical evidence for their existence is mostly lacking. In the current study we demonstrate that retrieval from verbal serial order WM can be facilitated or hindered by spatial cuing: begin elements of a verbal WM sequence are retrieved faster after cuing the left side of space, while end elements are retrieved faster after cuing the right side of space. In direct complement to our previous work--where we showed the reversed impact of WM retrieval on spatial processing--we argue that the current findings provide us with a crucial piece of evidence suggesting a direct and functional involvement of space in verbal serial order WM. We outline the idea that serial order in verbal WM is coded within a spatial coordinate system with spatial attention being involved when searching through WM, and we discuss how this account can explain several hallmark observations related to serial order WM.

Space Geodesy: The Cross-Disciplinary Earth science (Vening Meinesz Medal Lecture)

Science.gov (United States)

Shum, C. K.

2012-04-01

Geodesy during the onset of the 21st Century is evolving into a transformative cross-disciplinary Earth science field. The pioneers before or after the discipline Geodesy was defined include Galileo, Descartes, Kepler, Newton, Euler, Bernoulli, Kant, Laplace, Airy, Kelvin, Jeffreys, Chandler, Meinesz, Kaula, and others. The complicated dynamic processes of the Earth system manifested by interactions between the solid Earth and its fluid layers, including ocean, atmosphere, cryosphere and hydrosphere, and their feedbacks are linked with scientific problems such as global sea-level rise resulting from natural and anthropogenic climate change. Advances in the precision and stability of geodetic and fundamental instrumentations, including clocks, satellite or quasar tracking sensors, altimetry and lidars, synthetic aperture radar interferometry (InSAR), InSAR altimetry, gravimetry and gradiometry, have enabled accentuate and transformative progress in cross-disciplinary Earth sciences. In particular, advances in the measurement of the gravity with modern free-fall methods have reached accuracies of 10-9 g (~1 μGal or 10 nm/s2) or better, allowing accurate measurements of height changes at ~3 mm relative to the Earth's center of mass, and mass transports within the Earth interior or its geophysical fluids, enabling global quantifications of climate-change signals. These contemporary space geodetic and in situ sensors include, but not limited to, satellite radar and laser altimetry/lidars, GNSS/SLR/VLBI/DORIS, InSAR, spaceborne gravimetry from GRACE (Gravity Recovery And Climate Experiment twin-satellite mission) and gradiometry from GOCE (Global Ocean Circulation Experiment), tide gauges, and hydrographic data (XBT/MBT/Argo). The 2007 Intergovernmental Panel for Climate Change (IPCC) study, the Fourth Assessment Report (AR4), substantially narrowed the discrepancy between observation and the known geophysical causes of sea-level rise, but significant uncertainties

A geodetic matched-filter search for slow slip with application to the Mexico subduction zone

Science.gov (United States)

Rousset, B.; Campillo, M.; Lasserre, C.; Frank, W.; Cotte, N.; Walpersdorf, A.; Socquet, A.; Kostoglodov, V.

2017-12-01

Since the discovery of slow slip events, many methods have been successfully applied to model obvious transient events in geodetic time series, such as the widely used network strain filter. Independent seismological observations of tremors or low frequency earthquakes and repeating earthquakes provide evidence of low amplitude slow deformation but do not always coincide with clear occurrences of transient signals in geodetic time series. Here, we aim to extract the signal corresponding to slow slips hidden in the noise of GPS time series, without using information from independent datasets. We first build a library of synthetic slow slip event templates by assembling a source function with Green's functions for a discretized fault. We then correlate the templates with post-processed GPS time series. Once the events have been detected in time, we estimate their duration T and magnitude Mw by modelling a weighted stack of GPS time series. An analysis of synthetic time series shows that this method is able to resolve the correct timing, location, T and Mw of events larger than Mw 6.0 in the context of the Mexico subduction zone. Applied on a real data set of 29 GPS time series in the Guerrero area from 2005 to 2014, this technique allows us to detect 28 transient events from Mw 6.3 to 7.2 with durations that range from 3 to 39 days. These events have a dominant recurrence time of 40 days and are mainly located at the down dip edges of the Mw > 7.5 SSEs.

A geodetic matched filter search for slow slip with application to the Mexico subduction zone

Science.gov (United States)

Rousset, B.; Campillo, M.; Lasserre, C.; Frank, W. B.; Cotte, N.; Walpersdorf, A.; Socquet, A.; Kostoglodov, V.

2017-12-01

Since the discovery of slow slip events, many methods have been successfully applied to model obvious transient events in geodetic time series, such as the widely used network strain filter. Independent seismological observations of tremors or low-frequency earthquakes and repeating earthquakes provide evidence of low-amplitude slow deformation but do not always coincide with clear occurrences of transient signals in geodetic time series. Here we aim to extract the signal corresponding to slow slips hidden in the noise of GPS time series, without using information from independent data sets. We first build a library of synthetic slow slip event templates by assembling a source function with Green's functions for a discretized fault. We then correlate the templates with postprocessed GPS time series. Once the events have been detected in time, we estimate their duration T and magnitude Mw by modeling a weighted stack of GPS time series. An analysis of synthetic time series shows that this method is able to resolve the correct timing, location, T, and Mw of events larger than Mw 6 in the context of the Mexico subduction zone. Applied on a real data set of 29 GPS time series in the Guerrero area from 2005 to 2014, this technique allows us to detect 28 transient events from Mw 6.3 to 7.2 with durations that range from 3 to 39 days. These events have a dominant recurrence time of 40 days and are mainly located at the downdip edges of the Mw>7.5 slow slip events.

Positioning and tracking control system analysis for mobile free space optical network

Science.gov (United States)

Li, Yushan; Refai, Hazem; Sluss, , James J., Jr.; Verma, Pramode; LoPresti, Peter

2005-08-01

Free Space Optical (FSO) communication has evolved to be applied to the mobile network, because it can provide up to 2.5Gbps or higher data rate wireless communication. One of the key challenges with FSO systems is to maintain the Line of Sight (LOS) between transmitter and receiver. In this paper, the feasibility and performance of applying the FSO technology to the mobile network is explored, and the design plan of the attitude positioning and tracking control system of the FSO transceiver is investigated. First, the system architecture is introduced, the requirements for the control system are analyzed, the involved reference frames and frame transformation are presented. Second, the control system bandwidth is used to evaluate the system performance in controlling a positioning system consisting of a gimbal and a steering mirror, some definitions to describe the positioning accuracy and tracking capacity are given. The attitude control of a FSO transceiver is split into 2 similar channels: pitch and yaw. Using an equivalent linear control system model, the simulations are carried out, with and without the presence of uncertainties that includes GPS data errors and sensor measurement errors. Finally, based on the simulation results in the pitch channel, the quantitative evaluation on the performance of the control system is given, including positioning accuracy, tracking capability and uncertainty tolerance.

GPS-based satellite tracking system for precise positioning

Science.gov (United States)

Yunck, T. P.; Melbourne, W. G.; Thornton, C. L.

1985-01-01

NASA is developing a Global Positioning System (GPS) based measurement system to provide precise determination of earth satellite orbits, geodetic baselines, ionospheric electron content, and clock offsets between worldwide tracking sites. The system will employ variations on the differential GPS observing technique and will use a network of nine fixed ground terminals. Satellite applications will require either a GPS flight receiver or an on-board GPS beacon. Operation of the system for all but satellite tracking will begin by 1988. The first major satellite application will be a demonstration of decimeter accuracy in determining the altitude of TOPEX in the early 1990's. By then the system is expected to yield long-baseline accuracies of a few centimeters and instantaneous time synchronization to 1 ns.

A Unified Geodetic Vertical Velocity Field (UGVVF), Version 1.0

Science.gov (United States)

Schmalzle, G.; Wdowinski, S.

2014-12-01

Tectonic motion, volcanic inflation or deflation, as well as oil, gas and water pumping can induce vertical motion. In southern California these signals are inter-mingled. In tectonics, properly identifying regions that are contaminated by other signals can be important when estimating fault slip rates. Until recently vertical deformation rates determined by high precision Global Positioning Systems (GPS) had large uncertainties compared to horizontal components and were rarely used to constrain tectonic models of fault motion. However, many continuously occupied GPS stations have been operating for ten or more years, often delivering uncertainties of ~1 mm/yr or less, providing better constraints for tectonic modeling. Various processing centers produced GPS time series and estimated vertical velocity fields, each with their own set of processing techniques and assumptions. We compare vertical velocity solutions estimated by seven data processing groups as well as two combined solutions (Figure 1). These groups include: Central Washington University (CWU) and New Mexico Institute of Technology (NMT), and their combined solution provided by the Plate Boundary Observatory (PBO) through the UNAVCO website. Also compared are the Jet Propulsion Laboratory (JPL) and Scripps Orbit and Permanent Array Center (SOPAC) and their combined solution provided as part of the NASA MEaSUREs project. Smaller velocity fields included are from Amos et al., 2014, processed at the Nevada Geodetic Laboratory, Shen et al., 2011, processed by UCLA and called the Crustal Motion Map 4.0 (CMM4) dataset, and a new velocity field provided by the University of Miami (UM). Our analysis includes estimating and correcting for systematic vertical velocity and uncertainty differences between groups. Our final product is a unified velocity field that contains the median values of the adjusted velocity fields and their uncertainties. This product will be periodically updated when new velocity fields

Aspects Regarding the Establishment of the Scale Coefficient in the Case of Distances Measurements in an Geodetic Network

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Mircea Ortelecan

2016-11-01

Full Text Available The paper analyzes the possibility to establish the coefficient of scale towards the total station scale triangulation network in the conduct of geodetic and topographic observations in the points with known coordinates (old points or points whose coordinates we want to determine (new points. The purpose of the study is undertaken to simplify computing operations to reduce distances measured from the topographic surface to the Stereo 70 projection plan.

Optimization of observation plan based on the stochastic characteristics of the geodetic network

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Pachelski Wojciech

2016-06-01

Full Text Available Optimal design of geodetic network is a basic subject of many engineering projects. An observation plan is a concluding part of the process. Any particular observation within the network has through adjustment a different contribution and impact on values and accuracy characteristics of unknowns. The problem of optimal design can be solved by means of computer simulation. This paper presents a new method of simulation based on sequential estimation of individual observations in a step-by-step manner, by means of the so-called filtering equations. The algorithm aims at satisfying different criteria of accuracy according to various interpretations of the covariance matrix. Apart of them, the optimization criterion is also amount of effort, defined as the minimum number of observations required.

Fast Estimation Method of Space-Time Two-Dimensional Positioning Parameters Based on Hadamard Product

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Haiwen Li

2018-01-01

Full Text Available The estimation speed of positioning parameters determines the effectiveness of the positioning system. The time of arrival (TOA and direction of arrival (DOA parameters can be estimated by the space-time two-dimensional multiple signal classification (2D-MUSIC algorithm for array antenna. However, this algorithm needs much time to complete the two-dimensional pseudo spectral peak search, which makes it difficult to apply in practice. Aiming at solving this problem, a fast estimation method of space-time two-dimensional positioning parameters based on Hadamard product is proposed in orthogonal frequency division multiplexing (OFDM system, and the Cramer-Rao bound (CRB is also presented. Firstly, according to the channel frequency domain response vector of each array, the channel frequency domain estimation vector is constructed using the Hadamard product form containing location information. Then, the autocorrelation matrix of the channel response vector for the extended array element in frequency domain and the noise subspace are calculated successively. Finally, by combining the closed-form solution and parameter pairing, the fast joint estimation for time delay and arrival direction is accomplished. The theoretical analysis and simulation results show that the proposed algorithm can significantly reduce the computational complexity and guarantee that the estimation accuracy is not only better than estimating signal parameters via rotational invariance techniques (ESPRIT algorithm and 2D matrix pencil (MP algorithm but also close to 2D-MUSIC algorithm. Moreover, the proposed algorithm also has certain adaptability to multipath environment and effectively improves the ability of fast acquisition of location parameters.

Datum maintenance of the main Egyptian geodetic control networks by utilizing Precise Point Positioning “PPP” technique

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Mostafa Rabah

2016-06-01

To see how non-performing maintenance degrading the values of the HARN and NACN, the available HARN and NACN stations in the Nile Delta were observed. The Processing of the tested part was done by CSRS-PPP Service based on utilizing Precise Point Positioning “PPP” and Trimble Business Center “TBC”. The study shows the feasibility of Precise Point Positioning in updating the absolute positioning of the HARN network and its role in updating the reference frame (ITRF. The study also confirmed the necessity of the absent role of datum maintenance of Egypt networks.

A new laser-ranged satellite for General Relativity and space geodesy. III. De Sitter effect and the LARES 2 space experiment

Energy Technology Data Exchange (ETDEWEB)

Ciufolini, Ignazio [Universita del Salento, Dipt. Ingegneria dell' Innovazione, Lecce (Italy); Centro Fermi, Rome (Italy); Matzner, Richard [University of Texas, Theory Group, Austin (United States); Gurzadyan, Vahe [Alikhanian National Laboratory and Yerevan State University, Center for Cosmology and Astrophysics, Yerevan (Armenia); Penrose, Roger [University of Oxford, Mathematical Institute, Oxford (United Kingdom)

2017-12-15

In two previous papers we presented the LARES 2 space experiment aimed at a very accurate test of frame-dragging and at other tests of fundamental physics and measurements of space geodesy and geodynamics. We presented the error sources of the LARES 2 experiment, its error budget and Monte Carlo simulations and covariance analyses confirming an accuracy of a few parts in one thousand in the test of frame-dragging. Here we discuss the impact of the orbital perturbation known as the de Sitter effect, or geodetic precession, in the error budget of the LARES 2 frame-dragging experiment. We show that the uncertainty in the de Sitter effect has a negligible impact in the final error budget because of the very accurate results now available for the test of the de Sitter precession and because of its very nature. The total error budget in the LARES 2 test of frame-dragging remains at a level of the order of 0.2%, as determined in the first two papers of this series. (orig.)

A new laser-ranged satellite for General Relativity and space geodesy. III. De Sitter effect and the LARES 2 space experiment

International Nuclear Information System (INIS)

Ciufolini, Ignazio; Matzner, Richard; Gurzadyan, Vahe; Penrose, Roger

2017-01-01

In two previous papers we presented the LARES 2 space experiment aimed at a very accurate test of frame-dragging and at other tests of fundamental physics and measurements of space geodesy and geodynamics. We presented the error sources of the LARES 2 experiment, its error budget and Monte Carlo simulations and covariance analyses confirming an accuracy of a few parts in one thousand in the test of frame-dragging. Here we discuss the impact of the orbital perturbation known as the de Sitter effect, or geodetic precession, in the error budget of the LARES 2 frame-dragging experiment. We show that the uncertainty in the de Sitter effect has a negligible impact in the final error budget because of the very accurate results now available for the test of the de Sitter precession and because of its very nature. The total error budget in the LARES 2 test of frame-dragging remains at a level of the order of 0.2%, as determined in the first two papers of this series. (orig.)

Processing of a geodetic network determined in ETRS-89 with application of different cofactors

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Slavomír Labant

2012-12-01

Full Text Available At present, manufacturers characterize the accuracy of vectors measured by the static method of GNSS technology usingrelationship 5 mm + 1⋅ D ppm . The advantage of the GNSS system over other terrestrial technologies is that it is not affectedby uncertainties in the ground layers of the atmosphere. The paper presents experimental measurement of the 3D geodetic network usingthe technology of global navigation satellite systems, processing and analysis of measurements taken at the Čierny Váh pumping hydropowerstation. Observations were carried out in July 2008. The aim of the paper is to assess parameters used in the model to estimateparameters of the first and second order of the network structures.

A new planetary mapping for future space missions

Science.gov (United States)

Karachevtseva, Irina; Kokhanov, Alexander; Rodionova, Janna; Zubarev, Anatoliy; Nadezhdina, Irina; Kreslavsky, Mikhail; Oberst, Jürgen

2015-04-01

The wide studies of Solar system, including different planetary bodies, were announced by new Russian space program. Their geodesy and cartography support provides by MIIGAiK Extraterrestrial Laboratory (http://mexlab.miigaik.ru/eng) in frames of the new project "Studies of Fundamental Geodetic Parameters and Topography of Planets and Satellites". The objects of study are satellites of the outer planets (satellites of Jupiter - Europa, Calisto and Ganymede; Saturnine satellite Enceladus), some planets (Mercury and Mars) and the satellites of the terrestrial planets - Phobos (Mars) and the Moon (Earth). The new research project, which started in 2014, will address the following important scientific and practical tasks: - Creating new three-dimensional geodetic control point networks of satellites of the outer planets using innovative photogrammetry techniques; - Determination of fundamental geodetic parameters and study size, shape, and spin parameters and to create the basic framework for research of their surfaces; - Studies of relief of planetary bodies and comparative analysis of general surface characteristics of the Moon, Mars, and Mercury, as well as studies of morphometric parameters of volcanic formations on the Moon and Mars; - Modeling of meteoritic bombardment of celestial bodies and the study of the dynamics of particle emissions caused by a meteorite impacts; - Development of geodatabase for studies of planetary bodies, including creation of object catalogues, (craters and volcanic forms, etc.), and thematic mapping using GIS technology. The significance of the project is defined both by necessity of obtaining fundamental characteristics of the Solar System bodies, and practical tasks in preparation for future Russian and international space missions to the Jupiter system (Laplace-P and JUICE), the Moon (Luna-Glob and Luna-Resource), Mars (Exo-Mars), Mercury (Bepi-Colombo), and possible mission to Phobos (project Boomerang). For cartographic support of

Seismicity and seismic hazard in Sabah, East Malaysia from earthquake and geodetic data

Science.gov (United States)

Gilligan, A.; Rawlinson, N.; Tongkul, F.; Stephenson, R.

2017-12-01

While the levels of seismicity are low in most of Malaysia, the state of Sabah in northern Borneo has moderate levels of seismicity. Notable earthquakes in the region include the 1976 M6.2 Lahad Datu earthquake and the 2015 M6 Ranau earthquake. The recent Ranau earthquake resulted in the deaths of 18 people on Mt Kinabalu, an estimated 100 million RM ( US$23 million) damage to buildings, roads, and infrastructure from shaking, and flooding, reduced water quality, and damage to farms from landslides. Over the last 40 years the population of Sabah has increased to over four times what it was in 1976, yet seismic hazard in Sabah remains poorly understood. Using seismic and geodetic data we hope to better quantify the hazards posed by earthquakes in Sabah, and thus help to minimize risk. In order to do this we need to know about the locations of earthquakes, types of earthquakes that occur, and faults that are generating them. We use data from 15 MetMalaysia seismic stations currently operating in Sabah to develop a region-specific velocity model from receiver functions and a pre-existing surface wave model. We use this new velocity model to (re)locate earthquakes that occurred in Sabah from 2005-2016, including a large number of aftershocks from the 2015 Ranau earthquake. We use a probabilistic nonlinear earthquake location program to locate the earthquakes and then refine their relative locations using a double difference method. The recorded waveforms are further used to obtain moment tensor solutions for these earthquakes. Earthquake locations and moment tensor solutions are then compared with the locations of faults throughout Sabah. Faults are identified from high-resolution IFSAR images and subsequent fieldwork, with a particular focus on the Lahad Datau and Ranau areas. Used together, these seismic and geodetic data can help us to develop a new seismic hazard model for Sabah, as well as aiding in the delivery of outreach activities regarding seismic hazard

Assessing joint space and condylar position in the people with normal function of temporomandibular joint with cone-beam computed tomography

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Zahra Dalili

2012-01-01

Conclusion: The assessment of joint spaces in right and left sides should be done independently. Overall, the measured joint spaces except Sjs are not different in two sexes. The data from this study could be a useful and comparable reference for the clinical assessment of condylar position in patients with normal functional joints.

Study of Robust Position Recognition System of a Mobile Robot Using Multiple Cameras and Absolute Space Coordinates

Energy Technology Data Exchange (ETDEWEB)

Mo, Se Hyun [Amotech, Seoul (Korea, Republic of); Jeon, Young Pil [Samsung Electronics Co., Ltd. Suwon (Korea, Republic of); Park, Jong Ho [Seonam Univ., Namwon (Korea, Republic of); Chong, Kil To [Chon-buk Nat' 1 Univ., Junju (Korea, Republic of)

2017-07-15

With the development of ICT technology, the indoor utilization of robots is increasing. Research on transportation, cleaning, guidance robots, etc., that can be used now or increase the scope of future use will be advanced. To facilitate the use of mobile robots in indoor spaces, the problem of self-location recognition is an important research area to be addressed. If an unexpected collision occurs during the motion of a mobile robot, the position of the mobile robot deviates from the initially planned navigation path. In this case, the mobile robot needs a robust controller that enables the mobile robot to accurately navigate toward the goal. This research tries to address the issues related to self-location of the mobile robot. A robust position recognition system was implemented; the system estimates the position of the mobile robot using a combination of encoder information of the mobile robot and the absolute space coordinate transformation information obtained from external video sources such as a large number of CCTVs installed in the room. Furthermore, vector field histogram method of the pass traveling algorithm of the mobile robot system was applied, and the results of the research were confirmed after conducting experiments.

Study of Robust Position Recognition System of a Mobile Robot Using Multiple Cameras and Absolute Space Coordinates

International Nuclear Information System (INIS)

Mo, Se Hyun; Jeon, Young Pil; Park, Jong Ho; Chong, Kil To

2017-01-01

With the development of ICT technology, the indoor utilization of robots is increasing. Research on transportation, cleaning, guidance robots, etc., that can be used now or increase the scope of future use will be advanced. To facilitate the use of mobile robots in indoor spaces, the problem of self-location recognition is an important research area to be addressed. If an unexpected collision occurs during the motion of a mobile robot, the position of the mobile robot deviates from the initially planned navigation path. In this case, the mobile robot needs a robust controller that enables the mobile robot to accurately navigate toward the goal. This research tries to address the issues related to self-location of the mobile robot. A robust position recognition system was implemented; the system estimates the position of the mobile robot using a combination of encoder information of the mobile robot and the absolute space coordinate transformation information obtained from external video sources such as a large number of CCTVs installed in the room. Furthermore, vector field histogram method of the pass traveling algorithm of the mobile robot system was applied, and the results of the research were confirmed after conducting experiments.

Geodetic measurement of deformation east of the San Andreas Fault in Central California

Science.gov (United States)

Sauber, Jeanne; Solomon, Sean C.; Lisowski, Michael

1988-01-01

The shear strain rates in the Diablo Range of California have been calculated, and the slip rate along the Calaveras and Paicines faults in Central California have been estimated, on the basis of triangulation and trilateration data from two geodetic networks located between the western edge of the Great Valley and the San Andreas Fault. The orientation of the principal compressive strain predicted from the azimuth of the major structures in the region is N 25 deg E, leading to an average shear strain value that corresponds to a relative shortening rate of 4.5 + or - 2.4 mm/yr. It is inferred that the measured strain is due to compression across the fold of this area. The hypothesized uniform, fault-normal compression within the Coast Ranges is not supported by these results.

Installation of a seafloor geodetic network offshore northern Chile (GeoSEA)

Science.gov (United States)

Kopp, Heidrun; Lange, Dietrich; Hannemann, Katrin; Petersen, Florian; Contreras-Reyes, Eduardo

2016-04-01

The seafloor stores crucial information on sub-seafloor processes, including stress, elastic strain, and earthquake and tsunami generation. This information may be extracted through the nascent scientific field of seafloor geodesy. The target of the recently installed GeoSEA array (Geodetic Earthquake Observatory on the SEAfloor) is to measure crustal deformation in mm-scale on the marine forearc and outer rise of the South American subduction system around 21°S. This segment of the Nazca-South American plate boundary has last ruptured in an earthquake in 1877 and was identified as a seismic gap prior to the 2014 Iquique/Pisagua earthquake (Mw=8.1). The southern portion of the segment remains unbroken by a recent earthquake. Seafloor geodetic measurements provide a way to monitor crustal deformation at high resolution comparable to the satellite-based GPS technique upon which terrestrial geodesy is largely based. The GeoSEA Network consists of autonomous seafloor transponders installed on 4 m high tripods, which were lowered to the seabed on the deep-sea cable of RV SONNE in December 2015. The transponders within an array intercommunicate via acoustic signals for a period of up to 3.5 years and measure acoustic distance, tilt and pressure. An additional component of the network is GeoSURF, a self-steering autonomous surface vehicle (Wave Glider), which monitors system health and is capable to upload the seafloor data to the sea surface and to transfer it via satellite. We have chosen three areas on the middle and lower slope and the outer rise for the set-up of three sub-arrays. The array in Area 1 on the middle continental slope consists of 8 transponders located in pairs on four topographic ridges, which are surface expressions of faults at depth. Area 2 is located on the outer rise seaward of the trench where 5 stations monitor extension across plate-bending related normal faults. The third area is located at water depth >5000 m on the lower continental slope

NASA Space Geodesy Program: GSFC data analysis, 1992. Crustal Dynamics Project VLBI geodetic results, 1979 - 1991

Science.gov (United States)

Ryan, J. W.; Ma, C.; Caprette, D. S.

1993-01-01

The Goddard VLBI group reports the results of analyzing 1648 Mark 3 data sets acquired from fixed and mobile observing sites through the end of 1991, and available to the Crustal Dynamics Project. Two large solutions were used to obtain Earth rotation parameters, nutation offsets, radio source positions, site positions, site velocities, and baseline evolution. Site positions are tabulated on a yearly basis for 1979 to 1995, inclusive. Site velocities are presented in both geocentric Cartesian and topocentric coordinates. Baseline evolution is plotted for 200 baselines, and individual length determinations are presented for an additional 356 baselines. This report includes 155 quasar radio sources, 96 fixed stations and mobile sites, and 556 baselines.

Displacement response of a concrete arch dam to seasonal temperature fluctuations and reservoir level rise during the first filling period: evidence from geodetic data

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Cemal Ozer Yigit

2016-07-01

Full Text Available The present study evaluates the dynamic behaviour of the Ermenek Dam, the second highest dam in Turkey, based on conventional geodetic measurements and Finite Element Model (FEM analyses during its first filling period. In total, eight periods of measured deformation are considered from the end of construction until the reservoir reached its full capacity. The displacement response of the dam to the reservoir level and to seasonal temperature variations is examined in detail. Time series of apparent total displacements at the middle of the crest of the dam exhibits periodicity and linear trends. Correlation analysis revealed that periodic and linear displacement responses of the dam are related to variations of seasonal temperature and linearly increased reservoir level, respectively, indicating a relation between temperature, water load and dam deformation. It is also concluded that measured deformations based on geodetic data show good agreement with the predicted deformation obtained by the FEM analysis.

Development of position measuring technology by GPS; GPS ni yoru sokui gijutsu no kaihatsu

Energy Technology Data Exchange (ETDEWEB)

Ishizaki, T [Ministry of Transportation, Tokyo (Japan)

1994-07-25

With regard to the GPS (global positioning system) which uses the satellites launched and administered by the U.S.A. and has been utilized worldwide for ships, automobiles and geodetic surveys in recent years, Ministry of Transport started investigation and research on the application of its position measuring system from FY 1989. In this fiscal year, a study on position measuring methods and selection of the position measuring system to be developed were made, in FY 1991, the real-time functioning and track display were developed, in FY 1992, the initialization aboard the ship, the measure to prevent cycle slip, and the radio data communication technology were developed, and in FY 1993, a long term demonstration experiment presuming its practical use was conducted attaining the expected purpose. In this article, the developed real-time kinematic position measuring system is introduced. Regarding the position measuring methods by the GPS, there are the one point position measuring method and the relative position measuring method. Regarding this newly developed position measuring device, its application to work ships and structures can be considered in various ways. 4 figs.

The astro-geodetic use of CCD for gravity field refinement

Science.gov (United States)

Gerstbach, G.

1996-07-01

The paper starts with a review of geoid projects, where vertical deflections are more effective than gravimetry. In alpine regions the economy of astrogeoids is at least 10 times higher, but many countries do not make use of this fact - presumably because the measurements are not fully automated up to now. Based upon the experiences of astrometry of high satellites and own tests the author analyses the use of CCD for astro-geodetic measurements. Automation and speeding up will be possible in a few years, the latter depending on the observation scheme. Sensor characteristics, cooling and reading out of the devices should be harmonized. Using line sensors in small prism astrolabes, the CCD accuracy will reach the visual one (±0.2″) within 5-10 years. Astrogeoids can be combined ideally with geological data, because vertical variation of rock densities does not cause systematic effects (contrary to gravimetry). So a geoid of ±5 cm accuracy (achieved in Austria and other alpine countries by 5-10 points per 1000 km 2) can be improved to ±2 cm without additional observations and border effects.

Improving deformation models by discounting transient signals in geodetic data: 2. Geodetic data, stress directions, and long-term strain rates in Italy

Science.gov (United States)

Carafa, Michele M. C.; Bird, Peter

2016-07-01

The lithosphere of Italy is exposed to a number of different short-term strain transients, including but not limited to landslides, postseismic relaxation, and volcanic inflation/deflation. These transients affect GPS velocities and complicate the assessment of the long-term tectonic component of the surface deformation. In a companion paper we present a method for anticipating the principal patterns of nontectonic, short-term strains and building this information into the covariance matrix of the geodetic velocities. In this work we apply this method to Italian GPS velocities to build an augmented covariance matrix that characterizes all expected discrepancies between short- and long-term velocities. We find that formal uncertainties usually reported for GPS measurements are smaller than the variability of the same benchmarks across a geologic time span. Furthermore, we include in our modeling the azimuths of most compressive horizontal principal stresses (SHmax) because GPS data cannot resolve the active kinematics of coastal and offshore areas. We find that the final tectonic model can be made relatively insensitive to short-term interfering processes if the augmented covariance matrix and SHmax data records are used in the objective function. This results in a preferred neotectonic model that is also in closer agreement with independent geologic and seismological constraints and has the advantage of reducing short-term biases in forecasts of long-term seismicity.

Archiving Space Geodesy Data for 20+ Years at the CDDIS

Science.gov (United States)

Noll, Carey E.; Dube, M. P.

2004-01-01

Since 1982, the Crustal Dynamics Data Information System (CDDIS) has supported the archive and distribution of geodetic data products acquired by NASA programs. These data include GPS (Global Positioning System), GLONASS (GLObal NAvigation Satellite System), SLR (Satellite Laser Ranging), VLBI (Very Long Baseline Interferometry), and DORIS (Doppler Orbitography and Radiolocation Integrated by Satellite). The data archive supports NASA's space geodesy activities through the Solid Earth and Natural Hazards (SENH) program. The CDDIS data system and its archive have become increasingly important to many national and international programs, particularly several of the operational services within the International Association of Geodesy (IAG), including the International GPS Service (IGS), the International Laser Ranging Service (ILRS), the International VLBI Service for Geodesy and Astrometry (IVS), the International DORIS Service (IDS), and the International Earth Rotation Service (IERS). The CDDIS provides easy and ready access to a variety of data sets, products, and information about these data. The specialized nature of the CDDIS lends itself well to enhancement and thus can accommodate diverse data sets and user requirements. All data sets and metadata extracted from these data sets are accessible to scientists through ftp and the web; general information about each data set is accessible via the web. The CDDIS, including background information about the system and its user communities, the computer architecture, archive contents, available metadata, and future plans will be discussed.

Rupture history of the 2008 Mw 7.9 Wenchuan, China, earthquake: Evaluation of separate and joint inversions of geodetic, teleseismic, and strong-motion data

Science.gov (United States)

Hartzell, Stephen; Mendoza, Carlos; Ramírez-Guzmán, Leonardo; Zeng, Yuesha; Mooney, Walter

2013-01-01

An extensive data set of teleseismic and strong-motion waveforms and geodetic offsets is used to study the rupture history of the 2008 Wenchuan, China, earthquake. A linear multiple-time-window approach is used to parameterize the rupture. Because of the complexity of the Wenchuan faulting, three separate planes are used to represent the rupturing surfaces. This earthquake clearly demonstrates the strengths and limitations of geodetic, teleseismic, and strong-motion data sets. Geodetic data (static offsets) are valuable for determining the distribution of shallower slip but are insensitive to deeper faulting and reveal nothing about the timing of slip. Teleseismic data in the distance range 30°–90° generally involve no modeling difficulties because of simple ray paths and can distinguish shallow from deep slip. Teleseismic data, however, cannot distinguish between different slip scenarios when multiple fault planes are involved because steep takeoff angles lead to ambiguity in timing. Local strong-motion data, on the other hand, are ideal for determining the direction of rupture from directivity but can easily be over modeled with inaccurate Green’s functions, leading to misinterpretation of the slip distribution. We show that all three data sets are required to give an accurate description of the Wenchuan rupture. The moment is estimated to be approximately 1.0 × 1021 N · m with the slip characterized by multiple large patches with slips up to 10 m. Rupture initiates on the southern end of the Pengguan fault and proceeds unilaterally to the northeast. Upon reaching the cross-cutting Xiaoyudong fault, rupture of the adjacent Beichuan fault starts at this juncture and proceeds bilaterally to the northeast and southwest.

Separation of atmospheric, oceanic and hydrological polar motion excitation mechanisms based on a combination of geometric and gravimetric space observations

Science.gov (United States)

Göttl, F.; Schmidt, M.; Seitz, F.; Bloßfeld, M.

2015-04-01

The goal of our study is to determine accurate time series of geophysical Earth rotation excitations to learn more about global dynamic processes in the Earth system. For this purpose, we developed an adjustment model which allows to combine precise observations from space geodetic observation systems, such as Satellite Laser Ranging (SLR), Global Navigation Satellite Systems, Very Long Baseline Interferometry, Doppler Orbit determination and Radiopositioning Integrated on Satellite, satellite altimetry and satellite gravimetry in order to separate geophysical excitation mechanisms of Earth rotation. Three polar motion time series are applied to derive the polar motion excitation functions (integral effect). Furthermore we use five time variable gravity field solutions from Gravity Recovery and Climate Experiment to determine not only the integral mass effect but also the oceanic and hydrological mass effects by applying suitable filter techniques and a land-ocean mask. For comparison the integral mass effect is also derived from degree 2 potential coefficients that are estimated from SLR observations. The oceanic mass effect is also determined from sea level anomalies observed by satellite altimetry by reducing the steric sea level anomalies derived from temperature and salinity fields of the oceans. Due to the combination of all geodetic estimated excitations the weaknesses of the individual processing strategies can be reduced and the technique-specific strengths can be accounted for. The formal errors of the adjusted geodetic solutions are smaller than the RMS differences of the geophysical model solutions. The improved excitation time series can be used to improve the geophysical modeling.

How Well do we Know Near-Surface Density When Determining Mass Balance by the Geodetic Method?

Science.gov (United States)

Kuhn, M. H.; Matzi, E.

2005-12-01

From a data set of firn pits in the accumulation area of Hintereisferner in the years 1964 - 2002 the behavior of density and water equivalent was analyzed with a view to estimating the potential errors in the application of the geodetic method. Since annual specific balance ranged from 100 to 3300 mm w.e. the profiles were scaled to total depth. For the uppermost 10% of the annual deposit at a typical location the 1964-2002 mean density would be 350 kg/m-3 with a standard deviation of 110 kg/m-3; for the 10% layer at the base of the annual snowpack the respective figures are 510 +- 30 kg/m-3. The normalized long term means of an ensemble of 9 pits ranged from 310 to 380 kg/m-3 in the top layer and from 510 to 540 kg/m-3 in the bottom layer. When one outlier is removed the the range in the bottom layer reduces to 525 to 540 kg/m-3. This small local variance encourages the use of the geodetic method. The comparison of elevation models of 1969 and 1997 yields a mass change that agrees very well with the results of the glaciological method provided the volume change is converted to mass with a density of 900 kg/m-3. While this may be true for the entire glacier on long terms, it will fail for individual years in the accumulation area. Possible errors are calculated from the data set emphasizing the role of year to year changes of specific balance and accumulation area ratio.

Application of median-equation approach for outlier detection in geodetic networks

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Serif Hekimoglu

Full Text Available In geodetic measurements some outliers may occur sometimes in data sets, depending on different reasons. There are two main approaches to detect outliers as Tests for outliers (Baarda's and Pope's Tests and robust methods (Danish method, Huber method etc.. These methods use the Least Squares Estimation (LSE. The outliers affect the LSE results, especially it smears the effects of the outliers on the good observations and sometimes wrong results may be obtained. To avoid these effects, a method that does not use LSE should be preferred. The median is a high breakdown point estimator and if it is applied for the outlier detection, reliable results can be obtained. In this study, a robust method which uses median with or as a treshould value on median residuals that are obtained from median equations is proposed. If the a priori variance of the observations is known, the reliability of the new approch is greater than the one in the case where the a priori variance is unknown.

Regional Crustal Deformation and Lithosphere Thickness Observed with Geodetic Techniques

Science.gov (United States)

Vermeer, M.; Poutanen, M.; Kollo, K.; Koivula, H.; Ahola, J.

2009-04-01

The solid Earth, including the lithosphere, interacts in many ways with other components of the Earth system, oceans, atmosphere and climate. Geodesy is a key provider of data needed for global and environmental research. Geodesy provides methods and accurate measurements of contemporary deformation, sea level and gravity change. The importance of the decades-long stability and availability of reference frames must be stressed for such studies. In the future, the need to accurately monitor 3-D crustal motions will grow, both together with increasingly precise GNSS (Global Navigation Satellite System) positioning, demands for better follow-up of global change, and local needs for crustal motions, especially in coastal areas. These demands cannot yet be satisfied. The project described here is a part of a larger entity: Upper Mantle Dynamics and Quaternary Climate in Cratonic Areas, DynaQlim, an International Lithosphere Project (ILP) -sponsored initiative. The aims of DynaQlim are to understand the relations between upper mantle dynamics, mantle composition, physical properties, temperature and rheology, to study the postglacial uplift and ice thickness models, sea level change and isostatic response, Quaternary climate variations and Weichselian (Laurentian and other) glaciations during the late Quaternary. We aim at studying various aspects of lithospheric motion within the Finnish and Fennoscandian area, but within a global perspective, by the newest geodetic techniques in a multidisciplinary setting. The studies involve observations of three-dimensional motions and gravity change in a multidisciplinary context on a range of spatial scales: the whole of Fennoscandia, Finland, a regional test area of Satakunta, and the local test site Olkiluoto. Objectives of the research include improving our insight into the 3-D motion of a thick lithosphere, and into the gravity effect of the uplift, using novel approaches; improving the kinematic 3-D models in the

The Space Geodesy Project and Radio Frequency Interference Characterization and Mitigation

Science.gov (United States)

Lawrence, Hilliard M.; Beaudoin, C.; Corey, B. E.; Tourain, C. L.; Petrachenko, B.; Dickey, John

2013-01-01

The Space Geodesy Project (SGP) development by NASA is an effort to co-locate the four international geodetic techniques Satellite Laser Ranging (SLR) and Lunar Laser Ranging (LLR), Very Long Baseline Interferometry (VLBI), Global Navigation Satellite System (GNSS), and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) into one tightly referenced campus and coordinated reference frame analysis. The SGP requirement locates these stations within a small area to maintain line-of-sight and frequent automated survey known as the vector tie system. This causes a direct conflict with the new broadband VLBI technique. Broadband means 2-14 GHz, and RFI susceptibility at -80 dBW or higher due to sensitive RF components in the front end of the radio receiver.

Ergodic channel capacity of spatial correlated multiple-input multiple-output free space optical links using multipulse pulse-position modulation

Science.gov (United States)

Wang, Huiqin; Wang, Xue; Cao, Minghua

2017-02-01

The spatial correlation extensively exists in the multiple-input multiple-output (MIMO) free space optical (FSO) communication systems due to the channel fading and the antenna space limitation. Wilkinson's method was utilized to investigate the impact of spatial correlation on the MIMO FSO communication system employing multipulse pulse-position modulation. Simulation results show that the existence of spatial correlation reduces the ergodic channel capacity, and the reception diversity is more competent to resist this kind of performance degradation.

Dimensional regularization in position space and a forest formula for regularized Epstein-Glaser renormalization

Energy Technology Data Exchange (ETDEWEB)

Keller, Kai Johannes

2010-04-15

The present work contains a consistent formulation of the methods of dimensional regularization (DimReg) and minimal subtraction (MS) in Minkowski position space. The methods are implemented into the framework of perturbative Algebraic Quantum Field Theory (pAQFT). The developed methods are used to solve the Epstein-Glaser recursion for the construction of time-ordered products in all orders of causal perturbation theory. A solution is given in terms of a forest formula in the sense of Zimmermann. A relation to the alternative approach to renormalization theory using Hopf algebras is established. (orig.)

Dimensional regularization in position space and a forest formula for regularized Epstein-Glaser renormalization

International Nuclear Information System (INIS)

Keller, Kai Johannes

2010-04-01

The present work contains a consistent formulation of the methods of dimensional regularization (DimReg) and minimal subtraction (MS) in Minkowski position space. The methods are implemented into the framework of perturbative Algebraic Quantum Field Theory (pAQFT). The developed methods are used to solve the Epstein-Glaser recursion for the construction of time-ordered products in all orders of causal perturbation theory. A solution is given in terms of a forest formula in the sense of Zimmermann. A relation to the alternative approach to renormalization theory using Hopf algebras is established. (orig.)

Evidences of Episodic Crustal Magmatic Diapir and Shallow Volcanic Activity at Uturuncu, Central Andes, from Geodetic Observations between 2014 - 2017

Science.gov (United States)

Lau, H. N.; Tymofyeyeva, E.; Fialko, Y. A.

2017-12-01

Previous space geodetic studies using ERS-1/2 and Envisat Interferometric Synthetic Aperture Radar (InSAR) data revealed a broad uplift of 10 mm/yr within the Altiplano-Puna Volcanic Complex (APVC), centered at the Uturuncu volcano, surrounded by a ring of subsidence at a rate of a few millimeters per year. This pattern was attributed to formation of a diapir in the middle of the Altiplano-Puna Magma Body (APMB), at depth of 15-19 km. We use new data from the Sentinel-1 InSAR mission, collected between 2014-2017, to produce high-resolution maps of surface displacements in the satellite's line of sight (LOS) from 4 satellite tracks. We estimated random propagation effects (e.g. due to atmospheric turbulence) using a common-point stacking method by Tymofyeyeva and Fialko [2015] and estimated temporally-correlated propagation effects (e.g. due to seasonal variations in atmospheric moisture) using a regression of the residual phase against topography. The estimated atmospheric artifacts were removed from the interferograms prior to computing the time series of the LOS displacements. The data indicate that the uplift above the APMB has considerably slowed down compared to the 1992-2010 epoch. The observed variations in the uplift rate suggest that the "ballooning" of the mid-crustal diapir is episodic on time scales of year to decades, possibly due to variations in melt supply from the partially molten APMB to the incipient diapir. We also find a previously undiscovered localized uplift 11 km south of Uturuncu's peak with maximum LOS velocities of 10 - 15 mm/yr. Joint inversions of data from different satellite tracks for a point source of inflation in an elastic half space constrain the source depth to be at 2 km, suggestive of a shallow magma chamber or a hydrothermal system.

Geodezija od Mesopotamije do Globalnog geodetskog opažačkog sistema : Geodesy from Mesopotamie to Global Geodetic Observing System

Directory of Open Access Journals (Sweden)

Medžida Mulić

2015-12-01

Full Text Available Tokom šest milenijuma postojanja civilizacije na Zemlji, geodetske tehnike su doživjele teško sagledive promjene. Definicija i uloga geodezije su se mijenjale u skladu s tim promijenila. Geodezija (viša je evoluirala od svoje originalne klasične definicije da „proučava kretanja nebeskih tijela, oblik i dimenzije Zemlje“ u „znanost koja osim naprijed rečenog, proučava njene promjene i kompleksne dinamičke procese, koji djeluju unutar Zemlje, na njenoj površini i iznad njene površine, kao i u svemiru koji je okružuje. Rad predstavlja detaljan pregled geodetskih tehnika, instrumenata, katastra i kartografije kod starih civilizacija: Mesopotamije, starog Egipta, antičke Grčke, starog Rima, pa sve do Evropljana, između 17. stoljeća do modernog doba. Posebno su opisani geodetski radovi u Bosni i Hercegovini, od doba osmanlija, austro-ugarskog premjera, do savremenih dostignuća u polju premjera i primjene satelitskih modernih tehnika. Globalni geodetski opažački sistem-GGOS, glavna komponenta Internacionalne asocijacije za geodeziju, kao projekat za buduće generacije geodeta, opisan je na kraju. : During the six millennia of the existence of the civilization on the Earth, surveying techniques have been experienced difficult foreseeable changes. The definition and role of geodesy have been changing accordingly. Geodesy has evolved from its original classic definition that "studying the movements of celestial bodies, the shape and dimensions of the Earth" in the "science which, beside it noted above, studies its changes and complex dynamic processes that ongoing inside the Earth, on the surface, above its surfaces, and evironment. The paper is overview of the geodetic techniques and the surveying instruments, cadastre and cartography in the ancien civilizations: Mesopotamia, ancient Egypt, antic Greece, ancient Rome, to the Europeans, from the 17th century to modern times. A detailed description devoted to surveying and geodetic

Volcano-tectonic deformation in the Kivu Region, Central Africa: Results from six years of continuous GNSS observations of the Kivu Geodetic Network (KivuGNet)

Science.gov (United States)

Geirsson, Halldor; d'Oreye, Nicolas; Mashagiro, Niche; Syauswa, Muhindo; Celli, Gilles; Kadufu, Benjamin; Smets, Benoît; Kervyn, François

2017-10-01

We present an overview of the installation, operation, and initial results of the 15-station KivuGNet (Kivu Geodetic Network) in the Kivu Region, Central Africa. The network serves primarily as a research and monitoring tool for active volcanic, earthquake, and plate boundary processes in the region. Continuous operation of in-situ measurement networks in naturally and politically harsh environments is challenging, but has proven fruitful in this case. During the operation of the network since 2009, KivuGNet has captured: co-eruptive deformation from two eruptions of Nyamulagira (in 2010 and 2011-2012); inter-eruptive deformation, which we interpret as a combination of plate motion across the Western - East Africa Rift, and decreasing deep-seated magma accumulation under the Nyiragongo-Nyamulagira region; co-seismic deformation from the Mw5.8 August 7, 2015 Lwiro earthquake at the western border of Lake Kivu. We hope that this study will serve as a motivation for further implementation of in-situ geodetic networks in under-monitored and under-studied sections of the East African Rift.

Appropriation and dispossession by space

DEFF Research Database (Denmark)

Larsen, Troels Schultz

distinctions between place and position this paper outlines an empirical model analyzing 87 neglected housing estates in Denmark using (S)MCA. The analysis casts light on a number of homologies between physical space and social space. That enables us to comprehend physical space as a multidimensional space...... of peoples and assets (capital, resources, goods, services, facilities) in this space in and around the specific place. Position must be understood relationally as position in social space, which the given site occupies. That is as rank in the social order. Position can be defined by the properties...... of the people occupying the given site that situates them in social space vis-a-vis other positions. This way any site also becomes a more or less spontaneous fuzzy dual reading or symbolization of both its physicality and the people occupying the given site. Based on his relational thinking and the above...

Analytic-graphic testing of deformities at the waterworks Pod Bukovcom

Directory of Open Access Journals (Sweden)

Jeèný Miloš

2001-09-01

Full Text Available The paper presents some geodetic measurement results in a frame of deformity survey of the bulk dam at the waterworks Pod Bukovcom nearby Košice. Periodic geodetic position and levelling measurement are realized on the dam since 1999. Testing statistics are applied into the deformity survey. Geodetic data obtained from individual measurements in the geodetic network on the bulk dam at the waterworks Pod Bukovcom are adjusted using Gauss-Markov model. Accuracy analysis by means of using relative and confidence ellipses is complemented to geodetic measurements.

Geodetic Insights into the Earthquake Cycle in a Fold and Thrust Belt

Science.gov (United States)

Ingleby, T. F.; Wright, T. J.; Butterworth, V.; Weiss, J. R.; Elliott, J.

2017-12-01

Geodetic measurements are often sparse in time (e.g. individual interferograms) and/or space (e.g. GNSS stations), adversely affecting our ability to capture the spatiotemporal detail required to study the earthquake cycle in complex tectonic systems such as subaerial fold and thrust belts. In an effort to overcome these limitations we combine 3 generations of SAR satellite data (ERS 1/2, Envisat & Sentinel-1a/b) to obtain a 25 year, high-resolution surface displacement time series over the frontal portion of an active fold and thrust belt near Quetta, Pakistan where a Mw 7.1 earthquake doublet occurred in 1997. With these data we capture a significant portion of the seismic cycle including the interseismic, coseismic and postseismic phases. Each satellite time series has been referenced to the first ERS-1 SAR epoch by fitting a ground deformation model to the data. This allows us to separate deformation associated with each phase and to examine their relative roles in accommodating strain and creating topography, and to explore the relationship between the earthquake cycle and critical taper wedge mechanics. Modeling of the coseismic deformation suggests a long, thin rupture with rupture length 7 times greater than rupture width. Rupture was confined to a 20-30 degree north-northeast dipping reverse fault or ramp at depth, which may be connecting two weak decollements at approximately 8 km and 13 km depth. Alternatively, intersections between the coseismic fault plane and pre-existing steeper splay faults underlying folds may have played a significant role in inhibiting rupture, as evidenced by intersection points bordering the rupture. These fault intersections effectively partition the fault system down-dip and enable long, thin ruptures. Postseismic deformation is manifest as uplift across short-wavelength folds at the thrust front, with displacement rates decreasing with time since the earthquake. Broader patterns of postseismic uplift are also observed

Geodetic Infrastructure in the Ibiza and Barcelona Harbours for Sea Level Monitoring

Science.gov (United States)

Martinez-Benjamin, J. J.; Gili, J.; Lopez, R.; Tapia, A.; Perez, B.; Pros, F.

2013-12-01

The presentation is directed to the description of the actual situation and relevant information of the geodetic infrastructure of Ibiza and Barcelona sites for sea level determination and contribution to regional sea level rise. Time series are being analysed for mean sea level variations www.puertos.es. .In the framework of a Spanish Space Project, the instrumentation of sea level measurements has been improved by providing the Barcelona site with a radar tide gauge Datamar 2000C from Geonica s.l. near an acoustic tide gauge. Puertos del Estado installed in 2007 a MIROS radar tide gauge and the Barcelona Harbour Authority a GPS referente station in the roof of the new Control Tower situated in the Energy Pier. The radar sensor is over the water surface, on a L-shaped structure which elevates it a few meters above the quay shelf. 1-min data are transmitted to the ENAGAS Control Center by cable and then sent each 1 min to Puertos del Estado by e-mail. There is a GPS station Leica Geosystems GRX1200 GG Pro and antenna 1202. Precision levelling has been made several times in the last two years because the tower is founded in reclaimed land. The measured settlement rate is about 1cm/year that may be could mask the values registered by the tide gauge. A description of the actual infrastructure at Ibiza harbour at Marina de Botafoch, is presented and its applications to sea level monitoring and altimeter calibration in support of the main CGPS at Ibiza harbour. It is described the geometrical precision levelling made in June 2013 between the radar tide gauge and the GPS station. In particular, the CGPS located at Ibiza harbour is essential for its application to the marine campaign Baleares 2013, near Ibiza island. The main objective is to determine the altimeter bias for Jason-2, about 9:09 UTC September 15, 2013, and Saral/AltiKa, about 05:30 UTC September 16, UTC. These activities has been received funding of the Ministerio de Ciencia e Innovacion under Spanish

Learned Compact Local Feature Descriptor for Tls-Based Geodetic Monitoring of Natural Outdoor Scenes

Science.gov (United States)

Gojcic, Z.; Zhou, C.; Wieser, A.

2018-05-01

The advantages of terrestrial laser scanning (TLS) for geodetic monitoring of man-made and natural objects are not yet fully exploited. Herein we address one of the open challenges by proposing feature-based methods for identification of corresponding points in point clouds of two or more epochs. We propose a learned compact feature descriptor tailored for point clouds of natural outdoor scenes obtained using TLS. We evaluate our method both on a benchmark data set and on a specially acquired outdoor dataset resembling a simplified monitoring scenario where we successfully estimate 3D displacement vectors of a rock that has been displaced between the scans. We show that the proposed descriptor has the capacity to generalize to unseen data and achieves state-of-the-art performance while being time efficient at the matching step due the low dimension.

How the geometric calculus resolves the ordering ambiguity of quantum theory in curved space

International Nuclear Information System (INIS)

Pavsic, Matej

2003-01-01

The long standing problem of the ordering ambiguity in the definition of the Hamilton operator for a point particle in curved space is naturally resolved by using the powerful geometric calculus based on Clifford algebra. The momentum operator is defined to be the vector derivative (the gradient) multiplied by -i; it can be expanded in terms of basis vectors γ μ as p = -iγ μ ∂ μ . The product of two such operators is unambiguous, and such is the Hamiltonian which is just the d'Alembert operator in curved space; the curvature scalar term is not present in the Hamiltonian if we confine our consideration to scalar wavefunctions only. It is also shown that p is Hermitian and a self-adjoint operator: the presence of the basis vectors γ μ compensates the presence of √|g| in the matrix elements and in the scalar product. The expectation value of such an operator follows the classical geodetic line

Geodetic infrastructure at the Barcelona harbour for sea level monitoring

Science.gov (United States)

Martinez-Benjamin, Juan Jose; Gili, Josep; Lopez, Rogelio; Tapia, Ana; Pros, Francesc; Palau, Vicenc; Perez, Begona

2015-04-01

The presentation is directed to the description of the actual geodetic infrastructure of Barcelona harbour with three tide gauges of different technologies for sea level determination and contribution to regional sea level rise and understanding past and present sea level rise in the Barcelona harbour. It is intended that the overall system will constitute a CGPS Station of the ESEAS (European Sea Level) and TIGA (GPS Tide Gauge Benchmark Monitoring) networks. At Barcelona harbour there is a MIROS radar tide gauge belonging to Puertos del Estado (Spanish Harbours).The radar sensor is over the water surface, on a L-shaped structure which elevates it a few meters above the quay shelf. 1-min data are transmitted to the ENAGAS Control Center by cable and then sent each 1 min to Puertos del Estado by e-mail. The information includes wave forescast (mean period, significant wave height, sea level, etc.This sensor also measures agitation and sends wave parameters each 20 min. There is a GPS station Leica Geosystems GRX1200 GG Pro and antenna AX 1202 GG. The Control Tower of the Port of Barcelona is situated in the North dike of the so-called Energy Pier in the Barcelona harbor (Spain). This tower has different kind of antennas for navigation monitoring and a GNSS permanent station. As the tower is founded in reclaimed land, and because its metallic structure, the 50 m building is subjected to diverse movements, including periodic fluctuations due to temperature changes. In this contribution the 2009, 2011, 2012, 2013 and 2014 the necessary monitoring campaigns are described. In the framework of a Spanish Space Project, the instrumentation of sea level measurements has been improved by providing the Barcelona site with a radar tide gauge Datamar 2000C from Geonica S.L. in June 2014 near an acoustic tide gauge from the Barcelona Harbour installed in 2013. Precision levelling has been made several times in the last two years because the tower is founded in reclaimed land and

NChina16: A stable geodetic reference frame for geological hazard studies in North China

Science.gov (United States)

Wang, Guoquan; Bao, Yan; Gan, Weijun; Geng, Jianghui; Xiao, Gengru; Shen, Jack S.

2018-04-01

We have developed a stable North China Reference Frame 2016 (NChina16) using five years of continuous GPS observations (2011.8-2016.8) from 12 continuously operating reference stations (CORS) fixed to the North China Craton. Applications of NChina16 in landslide and subsidence studies are illustrated in this article. A method for realizing a regional geodetic reference frame is introduced. The primary result of this study is the seven parameters for transforming Cartesian ECEF (Earth-Centered, Earth-Fixed) coordinates X, Y, and Z from the International GNSS Service Reference Frame 2008 (IGS08) to NChina16. The seven parameters include the epoch that is used to align the regional reference frame to IGS08 and the time derivatives of three translations and three rotations. The GIPSY-OASIS (V6.4) software package was used to obtain the precise point positioning (PPP) daily solutions with respect to IGS08. The frame stability of NChina16 is approximately 0.5 mm/year in both horizontal and vertical directions. This study also developed a regional model for correcting seasonal motions superimposed into the vertical component of the GPS-derived displacement time series. Long-term GPS observations (1999-2016) from five CORS in North China were used to develop the seasonal model. According to this study, the PPP daily solutions with respect to NChina16 could achieve 2-3 mm horizontal accuracy and 4-5 mm vertical accuracy after being modified by the regional model. NChina16 will be critical to study geodynamic problems in North China, such as earthquakes, faulting, subsidence, and landslides. The regional reference frame will be periodically updated every few years to mitigate degradation of the frame with time and be synchronized with the update of IGS reference frame.

Viking telecommunication effects of GEOS satellite interference based on testing at the Madrid deep space station

Science.gov (United States)

Stuhr, F. V.; Kent, S. S.; Galvez, J. L.; Luaces, B. G.; Pasero, G. R.; Urech, J. M.

1976-01-01

In support of the ongoing NASA-European Space Agency (ESA) effort to understand and control possible interference between missions, testing was conducted at the Madrid Deep Space Station from July 1975 to February 1976 to characterize the effect on Viking 1975 telecommunication link performance of Geodetic Earth-Orbiting Satellite (GEOS) downlink signals. The prime use of the data was to develop a capability to predict GEOS interference effects for evaluation of Viking 1975 mission impacts and possible temporary GEOS shutdown. Also, the data would serve as a basis for assessment of the GEOS impact on missions other than Viking as well as for more general interference applications. Performances of the reference receiver, telemetry, and planetary ranging were measured in the presence of various types of GEOS-related interference, including an unmodulated GEOS carrier and simulation of the actual spectrum by an ESA-supplied GEOS suitcase model.

Ubiquitous positioning

CERN Document Server

Mannings, Robin

2008-01-01

This groundbreaking resource offers a practical, in-depth understanding of Ubiquitous Positioning - positioning systems that identify the location and position of people, vehicles and objects in time and space in the digitized networked economy. The future and growth of ubiquitous positioning will be fueled by the convergence of many other areas of technology, from mobile telematics, Internet technology, and location systems, to sensing systems, geographic information systems, and the semantic web. This first-of-its-kind volume explores ubiquitous positioning from a convergence perspective, of

Global positioning system theory and practice

CERN Document Server

Hofmann-Wellenhof, Bernhard; Collins, James

2001-01-01

This book is dedicated to Dr. Benjamin William Remondi for many reasons. The project of writing a Global Positioning System (GPS) book was con­ ceived in April 1988 at a GPS meeting in Darmstadt, Germany. Dr. Remondi discussed with me the need for an additional GPS textbook and suggested a possible joint effort. In 1989, I was willing to commit myself to such a project. Unfortunately, the timing was less than ideal for Dr. Remondi. Therefore, I decided to start the project with other coauthors. Dr. Remondi agreed and indicated his willingness to be a reviewer. I selected Dr. Herbert Lichtenegger, my colleague from the Technical University Graz, Austria, and Dr. James Collins from Rockville, Maryland, U.S.A. In my opinion, the knowledge ofthe three authors should cover the wide spectrum of GPS. Dr. Lichtenegger is a geodesist with broad experience in both theory and practice. He has specialized his research to geodetic astron­ omy including orbital theory and geodynamical phenomena. Since 1986, Dr. Lichteneg...

Spaces on sets

International Nuclear Information System (INIS)

Triebel, Hans

2005-01-01

This paper deals with spaces B s pq and F s pq of positive smoothness s>0, based on L p -spaces with 0< p≤∞ and reproducing formulae for smooth functions. These spaces are compared with other B-spaces and F-spaces obtained by different means

Geodetic Mass Balance of the Northern Patagonian Icefield from 2000 to 2012 Using Two Independent Methods

Directory of Open Access Journals (Sweden)

Inés Dussaillant

2018-02-01

Full Text Available We compare two independent estimates of the rate of elevation change and geodetic mass balance of the Northern Patagonian Icefield (NPI between 2000 (3,856 km2 and 2012 (3,740 km2 from space-borne data. The first is obtained by differencing the Shuttle Radar Topography Mission (SRTM digital elevation model (DEM from February 2000 and a Satellite pour l'Observation de la Terre 5 (SPOT5 DEM from March 2012. The second is deduced by fitting pixel-based linear elevation trends over 118 DEMs calculated from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER stereo images acquired between 2000 and 2012. Both methods lead to similar and strongly negative icefield-wide mass balance rates of −1.02 ± 0.21 and −1.06 ± 0.14 m w.e. yr−1 respectively, which is in agreement with earlier studies. Contrasting glacier responses are observed, with individual glacier mass balance rates ranging from −0.15 to −2.30 m w.e. yr−1 (standard deviation = 0.49 m w.e. yr−1; N = 38. For individual glaciers, the two methods agree within error bars, except for small glaciers poorly sampled in the SPOT5 DEM due to clouds. Importantly, our study confirms the lack of penetration of the C-band SRTM radar signal into the NPI snow and firn except for a region above 2,900 m a.s.l. covering <1% of the total area. Ignoring penetration would bias the mass balance by only 0.005 m w.e. yr−1. A strong advantage of the ASTER method is that it relies only on freely available data and can thus be extended to other glacierized areas.

Use of Geodetic Laser Scanning to Evaluate the Curvature of Bedrock Surfaces in an Investigation of Sheeting Joint Formation

Science.gov (United States)

Martel, S. J.; Mitchell, K.

2007-12-01

We are using aerial and tripod-mounted geodetic laser scanning (GLS) data, together with photography and large-scale geologic mapping, to investigate the formation of sheeting joints in Yosemite National Park. Sheeting joints are opening-mode fractures that form subparallel to the topography, and over broad areas in Yosemite they define the bedrock surface. Rock slabs bounded by sheeting joints superficially resemble the layers of an onion. Our hypothesis is that sheeting joints form where a tensile stress normal to the topographic surface exists in the shallow subsurface. This condition is met where k2 P22 + k3 P33 > γ cosβ, where k2 and k3 are the principal curvatures of the bedrock surface, P22 and P33 are the corresponding normal stresses parallel to the principal stresses, γ is the unit weight of the rock, and β is the slope angle. Sheeting joints are predicted where at least one of the principal curvatures is sufficiently convex (negative) and the corresponding normal stress is sufficiently compressive (negative). We use aerial GLS data with a vertical resolution of ~10 cm and a point spacing of ~1 m to measure the slope and curvature of the bedrock surface at the scale of a ridge or valley. We use tripod-mounted GLS data with a point spacing of ~5 cm, large-scale geologic mapping, and photographs to detect steps between consecutive sheeting joints, with the step height giving the sheet joint spacing. Outcrops hosting sheeting joints have a stair-step appearance with a distinctive curvature signature: high convex curvature at the top of a step, and high concave curvature at the step bottom. Steps between sheeting joints with a spacing of less than a meter or so are difficult to detect using the aerial GLS data. Apparently the interpolation of aerial data onto a grid, necessary for our curvature codes, and the smoothing of gridded data to filter out trees compromises the value of the aerial GLS data in detecting the step edges, even though the vertical

Single-baseline RTK GNSS Positioning for Hydrographic Surveying

Science.gov (United States)

Metin Alkan, Reha; Murat Ozulu, I.; Ilçi, Veli; Kahveci, Muzaffer

2015-04-01

Positioning with GNSS technique can be carried out in two ways, absolute and relative. It has been possible to reach a few meters absolute point positioning accuracies in real time after disabling SA permanently in May 2000. Today, accuracies obtainable from absolute point positioning using code observations are not sufficient for most surveying applications. Thus to meet higher accuracy requirements, differential methods using single or dual frequency geodetic-grade GNSS receivers that measure carrier phase have to be used. However, this method requires time-cost field and office works and if the measurement is not carried out with conventional RTK method, user needs a GNSS data processing software to estimate the coordinates. If RTK is used, at least two or more GNSS receivers are required, one as a reference and the other as a rover. Moreover, the distance between the receivers must not exceed 15-20 km in order to be able to rapidly and reliably resolve the carrier phase ambiguities. On the other hand, based on the innovations and improvements in satellite geodesy and GNSS modernization studies occurred within the last decade, many new positioning methods and new approaches have been developed. One of them is Network-RTK (or commonly known as CORS) and the other is Single-baseline RTK. These methods are widely used for many surveying applications in many countries. The user of the system can obtain his/her position within a few cm level of accuracy in real-time with only a single GNSS receiver that has Network RTK (CORS) capability. When compared with the conventional differential and RTK methods, this technique has several significant advantages as it is easy to use and it produces accurate, cost-effective and rapid solutions. In Turkey, establishment of a multi-base RTK network was completed and opened for civilian use in 2009. This network is called CORS-TR and consists of 146 reference stations having about 80-100 km interstation distances. It is possible

Pleural effusion adenosine deaminase: a candidate biomarker to discriminate between Gram-negative and Gram-positive bacterial infections of the pleural space

Directory of Open Access Journals (Sweden)

Ruolin Li

2016-05-01

Full Text Available OBJECTIVES: Delay in the treatment of pleural infection may contribute to its high mortality. In this retrospective study, we aimed to evaluate the diagnostic accuracy of pleural adenosine deaminase in discrimination between Gram-negative and Gram-positive bacterial infections of the pleural space prior to selecting antibiotics. METHODS: A total of 76 patients were enrolled and grouped into subgroups according to Gram staining: 1 patients with Gram-negative bacterial infections, aged 53.2±18.6 years old, of whom 44.7% had empyemas and 2 patients with Gram-positive bacterial infections, aged 53.5±21.5 years old, of whom 63.1% had empyemas. The pleural effusion was sampled by thoracocentesis and then sent for adenosine deaminase testing, biochemical testing and microbiological culture. The Mann-Whitney U test was used to examine the differences in adenosine deaminase levels between the groups. Correlations between adenosine deaminase and specified variables were also quantified using Spearman’s correlation coefficient. Moreover, receiver operator characteristic analysis was performed to evaluate the diagnostic accuracy of pleural effusion adenosine deaminase. RESULTS: Mean pleural adenosine deaminase levels differed significantly between Gram-negative and Gram-positive bacterial infections of the pleural space (191.8±32.1 U/L vs 81.0±16.9 U/L, p<0.01. The area under the receiver operator characteristic curve was 0.689 (95% confidence interval: 0.570, 0.792, p<0.01 at the cutoff value of 86 U/L. Additionally, pleural adenosine deaminase had a sensitivity of 63.2% (46.0-78.2%; a specificity of 73.7% (56.9-86.6%; positive and negative likelihood ratios of 2.18 and 0.50, respectively; and positive and negative predictive values of 70.6% and 66.7%, respectively. CONCLUSIONS: Pleural effusion adenosine deaminase is a helpful alternative biomarker for early and quick discrimination of Gram-negative from Gram-positive bacterial infections of the

Salpeter equation in position space: Numerical solution for arbitrary confining potentials

International Nuclear Information System (INIS)

Nickisch, L.J.; Durand, L.; Durand, B.

1984-01-01

We present and test two new methods for the numerical solution of the relativistic wave equation [(-del 2 +m 1 2 )/sup 1/2/+(-del 2 +m 2 2 )/sup 1/2/+V(r)-M]psi( r ) = 0, which appears in the theory of relativistic quark-antiquark bound states. Our methods work directly in position space, and hence have the desirable features that we can vary the potential V(r) locally in fitting the qq-bar mass spectrum, and can easily build in the expected behavior of V for r→0,infinity. Our first method converts the nonlocal square-root operators to mildly singular integral operators involving hyperbolic Bessel functions. The resulting integral equation can be solved numerically by matrix techniques. Our second method approximates the square-root operators directly by finite matrices. Both methods converge rapidly with increasing matrix size (the square-root matrix method more rapidly) and can be used in fast-fitting routines. We present some tests for oscillator and Coulomb interactions, and for the realistic Coulomb-plus-linear potential used in qq-bar phenomenology

Existence of positive solutions for nonlocal second-order boundary value problem with variable parameter in Banach spaces

Directory of Open Access Journals (Sweden)

Zhang Peiguo

2011-01-01

Full Text Available Abstract By obtaining intervals of the parameter λ, this article investigates the existence of a positive solution for a class of nonlinear boundary value problems of second-order differential equations with integral boundary conditions in abstract spaces. The arguments are based upon a specially constructed cone and the fixed point theory in cone for a strict set contraction operator. MSC: 34B15; 34B16.

VLBI TRF Combination Using GNSS Software

Directory of Open Access Journals (Sweden)

Younghee Kwak

2013-12-01

Full Text Available Space geodetic techniques can be used to obtain precise shape and rotation information of the Earth. To achieve this, the representative combination solution of each space geodetic technique has to be produced, and then those solutions need to be combined. In this study, the representative combination solution of very long baseline interferometry (VLBI, which is one of the space geodetic techniques, was produced, and the variations in the position coordinate of each station during 7 years were analyzed. Products from five analysis centers of the International VLBI Service for Geodesy and Astrometry (IVS were used as the input data, and Bernese 5.0, which is the global navigation satellite system (GNSS data processing software, was used. The analysis of the coordinate time series for the 43 VLBI stations indicated that the latitude component error was about 15.6 mm, the longitude component error was about 37.7 mm, and the height component error was about 30.9 mm, with respect to the reference frame, International Terrestrial Reference Frame 2008 (ITRF2008. The velocity vector of the 42 stations excluding the YEBES station showed a magnitude difference of 7.3 mm/yr (30.2% and a direction difference of 13.8° (3.8%, with respect to ITRF2008. Among these, the 10 stations in Europe showed a magnitude difference of 7.8 mm/yr (30.3% and a direction difference of 3.7° (1.0%, while the 14 stations in North America showed a magnitude difference of 2.7 mm/yr (15.8% and a direction difference of 10.3° (2.9%.

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

Science.gov (United States)

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.

Geodesy and the UNAVCO Consortium: Three Decades of Innovations

Science.gov (United States)

Rowan, L. R.; Miller, M. M.; Meertens, C. M.; Mattioli, G. S.

2015-12-01

UNAVCO, a non-profit, university consortium that supports geoscience research using geodesy, began with the ingenious recognition that the nascent Global Positioning System constellation (GPS) could be used to investigate earth processes. The consortium purchased one of the first commercially available GPS receivers, Texas Instrument's TI-4100 NAVSTAR Navigator, in 1984 to measure plate deformation. This early work was highlighted in a technology magazine, GPSWorld, in 1990. Over a 30-year period, UNAVCO and the community have helped advance instrument design for mobility, flexibility, efficiency and interoperability, so research could proceed with higher precision and under ever challenging conditions. Other innovations have been made in data collection, processing, analysis, management and archiving. These innovations in tools, methods and data have had broader impacts as they have found greater utility beyond research for timing, precise positioning, safety, communication, navigation, surveying, engineering and recreation. Innovations in research have expanded the utility of geodetic tools beyond the solid earth science through creative analysis of the data and the methods. For example, GPS sounding of the atmosphere is now used for atmospheric and space sciences. GPS reflectrometry, another critical advance, supports soil science, snow science and ecological research. Some research advances have had broader impacts for society by driving innovations in hazards risk reduction, hazards response, resource management, land use planning, surveying, engineering and other uses. Furthermore, the geodetic data is vital for the design of space missions, testing and advancing communications, and testing and dealing with interference and GPS jamming. We will discuss three decades (and counting) of advances by the National Science Foundation's premiere geodetic facility, consortium and some of the many geoscience principal investigators that have driven innovations in

STRUCTURAL MONITORING WITH GEODETIC SURVEY OF QUADRIFOGLIO CONDOMINIUM (LECCE

Directory of Open Access Journals (Sweden)

D. Costantino

2014-01-01

Full Text Available Monitoring buildings for moving elements has been always a problem of great importance for their conservation and preservation, as well as for risk mitigation. In particular, topographic surveying allows, through the use of the principles and instruments of the geodetic survey, to control moving points which have been identified and measured. In this study case, twelve survey campaigns were done for monitoring a building located in the city of Lecce. The condominium was built five years ago on an old quarry filled with debris to allow construction. Later in time, obviously, cracks started to appear on walls within the property, and for this legal actions were taken. The survey schema adopted has been that of triangulation/trilateration, from two vertices with known coordinates. With this methodologies four cornerstones have been identified, established with forced centering on pillars with anchor plates, connected to same number of framework points, considered stable. From these, 23 control points located on the structure with rotating prisms anchored at the same manner have been surveyed. The elaboration has been carried out by generating redundancy of the measures and compensating the values with least mean squares. The results obtained by the activity of survey and elaboration have confirmed the existence of ongoing phenomena. The causes that have generated the phenomenon have been, subsequently, investigated and have been considered attributable to the existence of a sewer pipeline and a water pipeline not properly put in place and consequently broke down due to the geological characteristics of the site.

On the assimilation of absolute geodetic dynamic topography in a global ocean model: impact on the deep ocean state

Science.gov (United States)

Androsov, Alexey; Nerger, Lars; Schnur, Reiner; Schröter, Jens; Albertella, Alberta; Rummel, Reiner; Savcenko, Roman; Bosch, Wolfgang; Skachko, Sergey; Danilov, Sergey

2018-05-01

General ocean circulation models are not perfect. Forced with observed atmospheric fluxes they gradually drift away from measured distributions of temperature and salinity. We suggest data assimilation of absolute dynamical ocean topography (DOT) observed from space geodetic missions as an option to reduce these differences. Sea surface information of DOT is transferred into the deep ocean by defining the analysed ocean state as a weighted average of an ensemble of fully consistent model solutions using an error-subspace ensemble Kalman filter technique. Success of the technique is demonstrated by assimilation into a global configuration of the ocean circulation model FESOM over 1 year. The dynamic ocean topography data are obtained from a combination of multi-satellite altimetry and geoid measurements. The assimilation result is assessed using independent temperature and salinity analysis derived from profiling buoys of the AGRO float data set. The largest impact of the assimilation occurs at the first few analysis steps where both the model ocean topography and the steric height (i.e. temperature and salinity) are improved. The continued data assimilation over 1 year further improves the model state gradually. Deep ocean fields quickly adjust in a sustained manner: A model forecast initialized from the model state estimated by the data assimilation after only 1 month shows that improvements induced by the data assimilation remain in the model state for a long time. Even after 11 months, the modelled ocean topography and temperature fields show smaller errors than the model forecast without any data assimilation.

Topological inversion for solution of geodesy-constrained geophysical problems

Science.gov (United States)

Saltogianni, Vasso; Stiros, Stathis

2015-04-01

Geodetic data, mostly GPS observations, permit to measure displacements of selected points around activated faults and volcanoes, and on the basis of geophysical models, to model the underlying physical processes. This requires inversion of redundant systems of highly non-linear equations with >3 unknowns; a situation analogous to the adjustment of geodetic networks. However, in geophysical problems inversion cannot be based on conventional least-squares techniques, and is based on numerical inversion techniques (a priori fixing of some variables, optimization in steps with values of two variables each time to be regarded fixed, random search in the vicinity of approximate solutions). Still these techniques lead to solutions trapped in local minima, to correlated estimates and to solutions with poor error control (usually sampling-based approaches). To overcome these problems, a numerical-topological, grid-search based technique in the RN space is proposed (N the number of unknown variables). This technique is in fact a generalization and refinement of techniques used in lighthouse positioning and in some cases of low-accuracy 2-D positioning using Wi-Fi etc. The basic concept is to assume discrete possible ranges of each variable, and from these ranges to define a grid G in the RN space, with some of the gridpoints to approximate the true solutions of the system. Each point of hyper-grid G is then tested whether it satisfies the observations, given their uncertainty level, and successful grid points define a sub-space of G containing the true solutions. The optimal (minimal) space containing one or more solutions is obtained using a trial-and-error approach, and a single optimization factor. From this essentially deterministic identification of the set of gridpoints satisfying the system of equations, at a following step, a stochastic optimal solution is computed corresponding to the center of gravity of this set of gridpoints. This solution corresponds to a

Hydrogen maser clocks in space for solid-Earth research and time-transfer applications: Experiment overview and evaluation of Russian miniature sapphire loaded cavity

Science.gov (United States)

Busca, G.; Bernier, L. G.; Silvestrin, P.; Feltham, S.; Gaygerov, B. A.; Tatarenkov, V. M.

1994-05-01

The Observatoire Cantonal de Neuchatel (ON) is developing for ESTEC a compact H-maser for space use based upon a miniature sapphire loaded microwave cavity, a technique pioneered at VNIIFTRI. Various contacts between West-European parties, headed by ESA, and the Russian parties, headed by ESA, led to the proposal for flying two H-masers on Meteor 3M, a Russian meteorology satellite in low polar orbit. The experiment will include two masers, one provided by ON and the other by VNIIFTRI. T/F transfer and precise positioning will be performed by both a microwave link, using PRARE equipment, and an optical link, using LASSO-like equipment. The main objectives of the experiment are precise orbit determination and point positioning for geodetic/geophysical research, ultra-accurate time comparison and dissemination as well as in-orbit demonstration of operation and performance of H-masers. Within the scope of a preliminary space H-maser development phase performed for ESTEC at ON in preparation to the joint experiment, a Russian miniature sapphire loaded microwave cavity, on loan from VNIIFTRI, was evaluated in a full-size EFOS hydrogen maser built by ON. The experimental evaluation confirmed the theoretical expectation that with a hydrogen storage volume of only 0.65 liter an atomic quality factor of 1.5 x 10(exp 9) can be obtained for a -105 dBm output power. This represents a theoretical Allan deviation of 1.7 x 10(exp -15) averaged on a 1000 s time interval. From a full-size design to a compact one, therefore, the sacrifice in performance due to the reduction of the storage volume is very small.

Need for denser geodetic network to get real constrain on the fault behavior along the Main Marmara Sea segments of the NAF, toward an optimized GPS network.

Science.gov (United States)

Klein, E.; Masson, F.; Duputel, Z.; Yavasoglu, H.; Agram, P. S.

2016-12-01

Over the last two decades, the densification of GPS networks and the development of new radar satellites offered an unprecedented opportunity to study crustal deformation due to faulting. Yet, submarine strike slip fault segments remain a major issue, especially when the landscape appears unfavorable to the use of SAR measurements. It is the case of the North Anatolian fault segments located in the Main Marmara Sea, that remain unbroken ever since the Mw7.4 earthquake of Izmit in 1999, which ended a eastward migrating seismic sequence of Mw > 7 earthquakes. Located directly offshore Istanbul, evaluation of seismic hazard appears capital. But a strong controversy remains over whether these segments are accumulating strain and are likely to experience a major earthquake, or are creeping, resulting both from the simplicity of current geodetic models and the scarcity of geodetic data. We indeed show that 2D infinite fault models cannot account for the complexity of the Marmara fault segments. But current geodetic data in the western region of Istanbul are also insufficient to invert for the coupling using a 3D geometry of the fault. Therefore, we implement a global optimization procedure aiming at identifying the most favorable distribution of GPS stations to explore the strain accumulation. We present here the results of this procedure that allows to determine both the optimal number and location of the new stations. We show that a denser terrestrial survey network can indeed locally improve the resolution on the shallower part of the fault, even more efficiently with permanent stations. But data closer from the fault, only possible by submarine measurements, remain necessary to properly constrain the fault behavior and its potential along strike coupling variations.

Studying Space: Improving Space Planning with User Studies

Science.gov (United States)

Pierard, Cindy; Lee, Norice

2011-01-01

How can libraries best assess and improve user space, even if they are not in a position to undertake new construction or a major renovation? Staff at New Mexico State University used a variety of ethnographic methods to learn how our spaces were being used as well as what our users considered to be ideal library space. Our findings helped us make…

14 CFR 99.15 - Position reports.

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Position reports. 99.15 Section 99.15 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES SECURITY CONTROL OF AIR TRAFFIC General § 99.15 Position reports. (a) The...

Do lightning positive leaders really "step"?

Science.gov (United States)

Petersen, D.

2015-12-01

It has been known for some time that positive leaders exhibit impulsive charge motion and optical emissions as they extend. However, laboratory and field observations have not produced any evidence of a process analogous to the space leader mechanism of negative leader extension. Instead, observations have suggested that the positive leader tip undergoes a continuous to intermittent series of corona streamer bursts, each burst resulting in a small forward extension of the positive leader channel. Traditionally, it has been held that lightning positive leaders extend in a continuous or quasi-continuous fashion. Lately, however, many have become concerned that this position is incongruous with observations of impulsive activity during lightning positive leader extension. It is increasingly suggested that this impulsive activity is evidence that positive leaders also undergo "stepping". There are two issues that must be addressed. The first issue concerns whether or not the physical processes underlying impulsive extension in negative and positive leaders are distinct. We argue that these processes are in fact physically distinct, and offer new high-speed video evidence to support this position. The second issue regards the proper use of the term "step" as an identifier for the impulsive forward extension of a leader. Traditional use of this term has been applied only to negative leaders, due primarily to their stronger impulsive charge motions and photographic evidence of clearly discontinuous forward progression of the luminous channel. Recently, due to the increasing understanding of the distinct "space leader" process of negative leader extension, the term "step" has increasingly come to be associated with the space leader process itself. Should this emerging association, "step" = space leader attachment, be canonized? If not, then it seems reasonable to use the term "step" to describe impulsive positive leader extension. If, however, we do wish to associate the

Geodetic antenna calibration test in the Antarctic environment

Science.gov (United States)

Grejner-Brzezinska, A.; Vazquez, E.; Hothem, L.

2006-01-01

TransAntarctic Mountain DEFormation (TAMDEF) Monitoring Network is the NSF-sponsored OSU and USGS project, aimed at measuring crustal motion in the Transantarctic Mountains of Victoria Land using GPS carrier phase measurements. Station monumentation, antenna mounts, antenna types, and data processing strategies were optimized to achieve mm-level estimates for the rates of motion. These data contributes also to regional Antarctic frame definition. Significant amount of data collected over several years allow the investigation of unique aspects of GPS geodesy in Antarctica, to determine how the error spectrum compares to the mid-latitude regions, and to identify the optimum measurement and data processing schemes for Antarctic conditions, in order to test the predicted rates of motion (mm-level w.r.t. time). The data collection for the TAMDEF project was initiated in 1996. The primary antenna used has been the Ashtech L1/L2 Dorne Margolin (D/M) choke ring. A few occupations involved the use of a Trimble D/M choke ring. The data were processed using the antenna calibration data available from the National Geodetic Survey (NGS). The recent developments in new antenna designs that are lighter in weight and lower in cost are being considered as a possible alternative to the bulkier and more expensive D/M choke ring design. In November 2003, in situ testing of three alternative models of L1/L2 antennas was conducted at a site located in the vicinity of McMurdo Station, Antarctica (S77.87, E166.56). The antenna models used in this test were: Ashtech D/M choke ring, Trimble D/M choke ring, Trimble Zephyr, and the NovAtel GPS-702. Two stations, spaced within 30 meters, were used in the test. Both had the characteristics similar to the stations of the TAMDEF network, i.e., the UNAVCO fixed-height, force-centered level mounts with a constant antenna offset were used, ensuring extreme stability of the antenna/ mount/pin set up. During each of the four 3-day test data collection

Evaluation of the space scattered dose according to the position of the radiation workers in mammography room

Energy Technology Data Exchange (ETDEWEB)

Lee, Dong Yeon [Dept. of Radiation Oncology, Dongnam Inst. of Radiological and Medical Science, Busan (Korea, Republic of); Lee, Jin Soo [Dept. of Radiology, Inje University Heaundae Paik Hospital, Busan (Korea, Republic of)

2016-09-15

This study was conducted to evaluate the dose of the space to the controller located within the mammography room conducted a research on ways to the reduction exposure to the radiation workers. Results, the dose of 6.18 mGy/year was measured when there is no difference in the hilar area of the controller position, the dose of 2.35E-11 mGy/year was measured when installing the Shielding door. In addition, when the direction of the X-ray tube anode be heading this direction controller, low average level measured was 0.30 mGy/year. Based on this study, the mammography should be considered when installing the anode and cathod directions. And, by installing the shielding door, it must be able to completely separate shooting space and control room. This is the best way radiation protection method in radiation workers.

Relationship between neighbourhood socioeconomic position and neighbourhood public green space availability: An environmental inequality analysis in a large German city applying generalized linear models.

Science.gov (United States)

Schüle, Steffen Andreas; Gabriel, Katharina M A; Bolte, Gabriele

2017-06-01

The environmental justice framework states that besides environmental burdens also resources may be social unequally distributed both on the individual and on the neighbourhood level. This ecological study investigated whether neighbourhood socioeconomic position (SEP) was associated with neighbourhood public green space availability in a large German city with more than 1 million inhabitants. Two different measures were defined for green space availability. Firstly, percentage of green space within neighbourhoods was calculated with the additional consideration of various buffers around the boundaries. Secondly, percentage of green space was calculated based on various radii around the neighbourhood centroid. An index of neighbourhood SEP was calculated with principal component analysis. Log-gamma regression from the group of generalized linear models was applied in order to consider the non-normal distribution of the response variable. All models were adjusted for population density. Low neighbourhood SEP was associated with decreasing neighbourhood green space availability including 200m up to 1000m buffers around the neighbourhood boundaries. Low neighbourhood SEP was also associated with decreasing green space availability based on catchment areas measured from neighbourhood centroids with different radii (1000m up to 3000 m). With an increasing radius the strength of the associations decreased. Social unequally distributed green space may amplify environmental health inequalities in an urban context. Thus, the identification of vulnerable neighbourhoods and population groups plays an important role for epidemiological research and healthy city planning. As a methodical aspect, log-gamma regression offers an adequate parametric modelling strategy for positively distributed environmental variables. Copyright © 2017 Elsevier GmbH. All rights reserved.

A New Neurocognitive Interpretation of Shoulder Position Sense during Reaching: Unexpected Competence in the Measurement of Extracorporeal Space

Directory of Open Access Journals (Sweden)

Teresa Paolucci

2016-01-01

Full Text Available Background. The position sense of the shoulder joint is important during reaching. Objective. To examine the existence of additional competence of the shoulder with regard to the ability to measure extracorporeal space, through a novel approach, using the shoulder proprioceptive rehabilitation tool (SPRT, during reaching. Design. Observational case-control study. Methods. We examined 50 subjects: 25 healthy and 25 with impingement syndrome with a mean age [years] of 64.52 +/− 6.98 and 68.36 +/− 6.54, respectively. Two parameters were evaluated using the SPRT: the integration of visual information and the proprioceptive afferents of the shoulder (Test 1 and the discriminative proprioceptive capacity of the shoulder, with the subject blindfolded (Test 2. These tasks assessed the spatial error (in centimeters by the shoulder joint in reaching movements on the sagittal plane. Results. The shoulder had proprioceptive features that allowed it to memorize a reaching position and reproduce it (error of 1.22 cm to 1.55 cm in healthy subjects. This ability was lower in the impingement group, with a statistically significant difference compared to the healthy group (p<0.05 by Mann–Whitney test. Conclusions. The shoulder has specific expertise in the measurement of the extracorporeal space during reaching movements that gradually decreases in impingement syndrome.

Spheroidal Integral Equations for Geodetic Inversion of Geopotential Gradients

Science.gov (United States)

Novák, Pavel; Šprlák, Michal

2018-03-01

The static Earth's gravitational field has traditionally been described in geodesy and geophysics by the gravitational potential (geopotential for short), a scalar function of 3-D position. Although not directly observable, geopotential functionals such as its first- and second-order gradients are routinely measured by ground, airborne and/or satellite sensors. In geodesy, these observables are often used for recovery of the static geopotential at some simple reference surface approximating the actual Earth's surface. A generalized mathematical model is represented by a surface integral equation which originates in solving Dirichlet's boundary-value problem of the potential theory defined for the harmonic geopotential, spheroidal boundary and globally distributed gradient data. The mathematical model can be used for combining various geopotential gradients without necessity of their re-sampling or prior continuation in space. The model extends the apparatus of integral equations which results from solving boundary-value problems of the potential theory to all geopotential gradients observed by current ground, airborne and satellite sensors. Differences between spherical and spheroidal formulations of integral kernel functions of Green's kind are investigated. Estimated differences reach relative values at the level of 3% which demonstrates the significance of spheroidal approximation for flattened bodies such as the Earth. The observation model can be used for combined inversion of currently available geopotential gradients while exploring their spectral and stochastic characteristics. The model would be even more relevant to gravitational field modelling of other bodies in space with more pronounced spheroidal geometry than that of the Earth.

Insights into the 3D architecture of an active caldera ring-fault at Tendürek volcano through modeling of geodetic data

KAUST Repository

Vasyura-Bathke, Hannes

2015-04-28

The three-dimensional assessment of ring-fault geometries and kinematics at active caldera volcanoes is typically limited by sparse field, geodetic or seismological data, or by only partial ring-fault rupture or slip. Here we use a novel combination of spatially dense InSAR time-series data, numerical models and sand-box experiments to determine the three-dimensional geometry and kinematics of a sub-surface ring-fault at Tendürek volcano in Turkey. The InSAR data reveal that the area within the ring-fault not only subsides, but also shows substantial westward-directed lateral movement. The models and experiments explain this as a consequence of a ‘sliding-trapdoor’ ring-fault architecture that is mostly composed of outward-inclined reverse segments, most markedly so on the volcano\\'s western flanks but includes inward-inclined normal segments on its eastern flanks. Furthermore, the model ring-fault exhibits dextral and sinistral strike-slip components that are roughly bilaterally distributed onto its northern and southern segments, respectively. Our more complex numerical model describes the deformation at Tendürek better than an analytical solution for a single rectangular dislocation in a half-space. Comparison to ring-faults defined at Glen Coe, Fernandina and Bárðarbunga calderas suggests that ‘sliding-trapdoor’ ring-fault geometries may be common in nature and should therefore be considered in geological and geophysical interpretations of ring-faults at different scales worldwide.

Positioning consumption

DEFF Research Database (Denmark)

Halkier, Bente; Keller, Margit

2014-01-01

positionings emerges based on empirical examples of research in parent–children consumption. Positionings are flexible discursive fixations of the relationship between the performances of the practitioner, other practitioners, media discourse and consumption activities. The basic positioning types...... are the practice maintenance and the practice change position, with different sorts of adapting in between. Media discourse can become a resource for a resistant position against social control or for an appropriating position in favour of space for action. Regardless of the current relation to a particular media......This article analyses the ways in which media discourses become a part of contested consumption activities. We apply a positioning perspective with practice theory to focus on how practitioners relate to media discourse as a symbolic resource in their everyday practices. A typology of performance...

An Adaptive Regulator for Space Teleoperation System in Task Space

Directory of Open Access Journals (Sweden)

Chao Ge

2014-01-01

Full Text Available The problem of the gravity information which can not be obtained in advance for bilateral teleoperation is studied. In outer space exploration, the gravity term changes with the position changing of the slave manipulator. So it is necessary to design an adaptive regulator controller to compensate for the unknown gravity signal. Moreover, to get a more accurate position tracking performance, the controller is designed in the task space instead of the joint space. Additionally, the time delay considered in this paper is not only time varying but also unsymmetrical. Finally, simulations are presented to show the effectiveness of the proposed approach.

Creating Inclusive Physical Activity Spaces: The Case of Body-Positive Yoga.

Science.gov (United States)

Pickett, Andrew C; Cunningham, George B

2017-09-01

Within the modern cultural climate, those in larger bodies face high levels of weight stigma, particularly in sport and physical activity spaces, which serves as a strong barrier to their participation. However, given the strong link between physical activity and general health and well-being for participants, it is important to explore strategies that encourage participation of these individuals. Thus, the current research examined strategies that physical activity instructors use to develop inclusive exercise spaces for all body sizes. This study employed a series of semistructured qualitative interviews (n = 9) with instructors of body-inclusive yoga classes to explore the ways in which they encourage participation for those in larger bodies. Emergent themes from the current study suggested support for 6 factors for creating body-inclusive physical activity spaces: authentic leadership, a culture of inclusion, a focus on health, inclusive language, leader social activism, and a sense of community. This study revealed that leaders must intentionally cultivate inclusion in their spaces to encourage those in nonconforming bodies to participate. These findings have important health and management implications for the sport and physical activity context and provide a basic outline of practical strategies that practitioners can use to foster inclusion in their spaces.

Geodetic Finite-Fault-based Earthquake Early Warning Performance for Great Earthquakes Worldwide

Science.gov (United States)

Ruhl, C. J.; Melgar, D.; Grapenthin, R.; Allen, R. M.

2017-12-01

GNSS-based earthquake early warning (EEW) algorithms estimate fault-finiteness and unsaturated moment magnitude for the largest, most damaging earthquakes. Because large events are infrequent, algorithms are not regularly exercised and insufficiently tested on few available datasets. The Geodetic Alarm System (G-larmS) is a GNSS-based finite-fault algorithm developed as part of the ShakeAlert EEW system in the western US. Performance evaluations using synthetic earthquakes offshore Cascadia showed that G-larmS satisfactorily recovers magnitude and fault length, providing useful alerts 30-40 s after origin time and timely warnings of ground motion for onshore urban areas. An end-to-end test of the ShakeAlert system demonstrated the need for GNSS data to accurately estimate ground motions in real-time. We replay real data from several subduction-zone earthquakes worldwide to demonstrate the value of GNSS-based EEW for the largest, most damaging events. We compare predicted ground acceleration (PGA) from first-alert-solutions with those recorded in major urban areas. In addition, where applicable, we compare observed tsunami heights to those predicted from the G-larmS solutions. We show that finite-fault inversion based on GNSS-data is essential to achieving the goals of EEW.

New insights into the magma chamber activity under Mauna Loa inferred from SBAS-InSAR and geodetic inversion modelling

Science.gov (United States)

Varugu, B. K.; Amelung, F.

2017-12-01

Mauna Loa volcano, located on the Big Island, Hawaii, is the largest volcano on the earth and historically been one of the most active volcanoes on the earth. Since its last eruption in 1984, there was a decrease in the magmatic activity, yet episodic inflations with increased seismicity sparks interests in the scientific community and there is strong need to monitor the volcano with growing infrastructure close to the flanks of the volcano. Geodetic modelling of the previous inflations illustrate that the magma activity is due to inflation of hydraulically connected dike and magma chamber located from 4-8km beneath the summit (Amelung et al. 2007). Most of the seismicity observed on Mauna Loa is due to the movement along a decollement fault situated at the base of the volcano. Magma inflation under Mauna Loa has started again during the last quarter of 2013 and is continuing still with an increased seismicity. In this study, we used 140 images form COSMO SkyMED between 2013-2017 to derive and model the ground deformation. We carried out time series InSAR analysis using Small Baseline (SB) approach. While the deformation pattern seems similar in many ways to the previous inflation periods, geodetic modelling for inversion of source parameters indicate a significant propagation of the dike ( 1 km) into the South West Rift Zone(SWRZ) and a decreased depth of the dike top from summit, compared to the previous inflations. Such propagation needs to be studied further in view of the steep slope of SWRZ. In understanding the dynamics of this propagating dike, we also observed an increased seismic activity since 2014 in the vicinity of the modelled dike. Here in this study we attempt to characterize the stresses induced by the propagating dike and seaward slipping movement along the basal decollement, to explain the increased seismicity using a finite element model.

A physicalist reinterpretation of ‘phenomenal’ spaces

NARCIS (Netherlands)

Decock, L.B.

2006-01-01

This paper argues that phenomenal or internal metrical spaces are redundant posits. It is shown that we need not posit an internal space-time frame, as the physical space-time suffices to explain geometrical perception, memory and planning. More than the internal space-time frame, the idea of a

Positive-Operator Valued Measure (POVM Quantization

Directory of Open Access Journals (Sweden)

Jean Pierre Gazeau

2014-12-01

Full Text Available We present a general formalism for giving a measure space paired with a separable Hilbert space a quantum version based on a normalized positive operator-valued measure. The latter are built from families of density operators labeled by points of the measure space. We especially focus on various probabilistic aspects of these constructions. Simple ormore elaborate examples illustrate the procedure: circle, two-sphere, plane and half-plane. Links with Positive-Operator Valued Measure (POVM quantum measurement and quantum statistical inference are sketched.

Self-force correction to geodetic spin precession in Kerr spacetime

Science.gov (United States)

Akcay, Sarp

2017-08-01

We present an expression for the gravitational self-force correction to the geodetic spin precession of a spinning compact object with small, but non-negligible mass in a bound, equatorial orbit around a Kerr black hole. We consider only conservative backreaction effects due to the mass of the compact object (m1), thus neglecting the effects of its spin s1 on its motion; i.e., we impose s1≪G m12/c and m1≪m2, where m2 is the mass parameter of the background Kerr spacetime. We encapsulate the correction to the spin precession in ψ , the ratio of the accumulated spin-precession angle to the total azimuthal angle over one radial orbit in the equatorial plane. Our formulation considers the gauge-invariant O (m1) part of the correction to ψ , denoted by Δ ψ , and is a generalization of the results of Akcay et al. [Classical Quantum Gravity 34, 084001 (2017), 10.1088/1361-6382/aa61d6] to Kerr spacetime. Additionally, we compute the zero-eccentricity limit of Δ ψ and show that this quantity differs from the circular orbit Δ ψcirc by a gauge-invariant quantity containing the gravitational self-force correction to general relativistic periapsis advance in Kerr spacetime. Our result for Δ ψ is expressed in a manner that readily accommodates numerical/analytical self-force computations, e.g., in the radiation gauge, and paves the way for the computation of a new eccentric-orbit Kerr gauge invariant beyond the generalized redshift.

Development of AN Open-Source Automatic Deformation Monitoring System for Geodetical and Geotechnical Measurements

Science.gov (United States)

Engel, P.; Schweimler, B.

2016-04-01

The deformation monitoring of structures and buildings is an important task field of modern engineering surveying, ensuring the standing and reliability of supervised objects over a long period. Several commercial hardware and software solutions for the realization of such monitoring measurements are available on the market. In addition to them, a research team at the Neubrandenburg University of Applied Sciences (NUAS) is actively developing a software package for monitoring purposes in geodesy and geotechnics, which is distributed under an open source licence and free of charge. The task of managing an open source project is well-known in computer science, but it is fairly new in a geodetic context. This paper contributes to that issue by detailing applications, frameworks, and interfaces for the design and implementation of open hardware and software solutions for sensor control, sensor networks, and data management in automatic deformation monitoring. It will be discussed how the development effort of networked applications can be reduced by using free programming tools, cloud computing technologies, and rapid prototyping methods.

Congruence analysis of geodetic networks - hypothesis tests versus model selection by information criteria

Science.gov (United States)

Lehmann, Rüdiger; Lösler, Michael

2017-12-01

Geodetic deformation analysis can be interpreted as a model selection problem. The null model indicates that no deformation has occurred. It is opposed to a number of alternative models, which stipulate different deformation patterns. A common way to select the right model is the usage of a statistical hypothesis test. However, since we have to test a series of deformation patterns, this must be a multiple test. As an alternative solution for the test problem, we propose the p-value approach. Another approach arises from information theory. Here, the Akaike information criterion (AIC) or some alternative is used to select an appropriate model for a given set of observations. Both approaches are discussed and applied to two test scenarios: A synthetic levelling network and the Delft test data set. It is demonstrated that they work but behave differently, sometimes even producing different results. Hypothesis tests are well-established in geodesy, but may suffer from an unfavourable choice of the decision error rates. The multiple test also suffers from statistical dependencies between the test statistics, which are neglected. Both problems are overcome by applying information criterions like AIC.

Determination of recent horizontal crustal movements and deformations of African and Eurasian plates in western Mediterranean region using geodetic-GPS computations extended to 2006 (from 1997) related to NAFREF and AFREF frames.

Science.gov (United States)

Azzouzi, R.

2009-04-01

Western Mediterranean and especially on Morocco. Exploiting parameters of positions and dispersions of these stations within the 1997-2003 period, the motion and the interaction types of interaction between African and Eurasian tectonic plates can be estimated. Similarly, the crustal dynamic parameters of tension of these sites will be computed. The time occupation on repeated observations sites is at least 72 hours. The measurements are continuous on permanent stations. The precise ephemerides are used in GPS computations. The post-treatments are done using commercial and scientific softwares. The coordinates obtained for two consecutive periods to and t within a period of 8 years will be used by programs established for this purpose to estimate crustal dynamic parameters of tension as well as to evaluate the appropriate movements. Even crustal dynamic parameters will be determined on each sites of the GPS-Geodynamics network, whose interest of seismic investigations is very important. This will allow best knowledge of substantial seismic activities of the surrounding zones. It can be deduced by measuring the motions and their parameter tensions using GPS. These estimations will contribute on the earthquake prediction by supervising the strain accumulation and its release in the active areas. For the geodetically aspect the GPS-Geodynamics sites computed in the ITRF frame can be used with other similar ounces' of Africa country and some well selected and convenient IGS, EUREF stations..to determine first the NAFREF and the AFRER frames.

Dual joint space arthrography in temporomandibular joint disorders: Comparison with single inferior joint space arthrography

Energy Technology Data Exchange (ETDEWEB)

Choi, Hyung Sik; Chang, Duk Soo; Lee, Kyung Soo; Kim, Woo Sun; Sung, Jung Ho; Jun, Young Hwan [Capital Armed Forces General Hospital, Seoul (Korea, Republic of)

1989-02-15

The temporomandibular joint(TMJ) is really a complex of two synovial space separated by fibrocartilaginous disc. Single inferior joint space arthrography is commonly performed for evaluation of TMJ disorders, which is known to be superior in demonstrating joint dynamics. But it reveals only the inferior surface of the disc. Therefore, dual space arthrography is superior to demonstrate the soft tissue anatomic feature of the joint such as disc position and shape. Authors performed 83 TMJ arthrograms in TMJ problems. Initially, the inferior joint space was done and then the superior space was sequentially contrasted. The follow results were noted: 1. In all cases, dual space arthrography revealed accurate disc shape and positions. 2. Concordant findings between the two techniques: 68 cases (82%). Discordance between the two techniques: 15 cases (18%) 3. Possible causes of discordance between inferior and dual space arthrography. a) Normal varians of anterior recess: 3 cases b) Posterior disc displacement: 4 cases c) Influence of the patient's head position change :4 cases d) False perforation: 2 cases e) Reduction change: 2 cases 4. In 5 cases with anterior displacement, dual space arthrography gave additional findings such as adhesion within the superior space, which could not be evaluated by single inferior space.

Ergonomic Evaluation of Space Shuttle Light-Weight Seat Lever Position and Operation

Science.gov (United States)

Maida, J.; Rajulu, Sudhakar L.; Bond, Robert L. (Technical Monitor)

2000-01-01

During a Shuttle flight in the early part of 1999, one of the crewmembers was unable to operate the backrest lever for the light-weight seat in microgravity. It is essential that the crewmembers are able to adjust this back-rest lever, which is titled forward 2 degrees from vertical during launch and then moved backwards to 10 degrees aft of vertical upon reaching orbit. This adjustment is needed to cushion the crewmembers during an inadvertent crash landing situation. The original Shuttle seats, which had seat controls located on the front left and right sides of the seat, were replaced recently with the new light-weight seats. The controls for these new, seats were moved to the night side with one control at the front and the other at the back. While it was uncertain whether the problem encountered was unique to that crewmember or not it was clear to the personnel responsible for maintaining the Shuttle seats that not knowing the cause of the problem posed a safety concern for NASA. Hence the Anthropometry and Biomechanics Facility (ABF) of the Johnson Space Center was requested to perform an evaluation of the seat controls and provide NASA with appropriate recommendations on whether the seat lever positions and operations should be modified. The ABF designed an experiment to investigate the amount of pull force exerted by subjects, wearing an unpressurized or pressurized crew launch escape suit, when controls were placed in the front and back (on the right side) of the light-weight seat. Single-axis load cells were attached to the seat levers, which measured the maximum static pull forces that were exerted by the subjects. Twelve subjects, six male and six female, participated in this study. Each subject was asked to perform the pull test at least three times for each combination of lever position and suit pressure conditions. The results from this study showed that as a whole (or in general), the subjects were able to pull on the lever at the back position with

Integrating Remote Sensing Data, Hybrid-Cloud Computing, and Event Notifications for Advanced Rapid Imaging & Analysis (Invited)

Science.gov (United States)

Hua, H.; Owen, S. E.; Yun, S.; Lundgren, P.; Fielding, E. J.; Agram, P.; Manipon, G.; Stough, T. M.; Simons, M.; Rosen, P. A.; Wilson, B. D.; Poland, M. P.; Cervelli, P. F.; Cruz, J.

2013-12-01

Space-based geodetic measurement techniques such as Interferometric Synthetic Aperture Radar (InSAR) and Continuous Global Positioning System (CGPS) are now important elements in our toolset for monitoring earthquake-generating faults, volcanic eruptions, hurricane damage, landslides, reservoir subsidence, and other natural and man-made hazards. Geodetic imaging's unique ability to capture surface deformation with high spatial and temporal resolution has revolutionized both earthquake science and volcanology. Continuous monitoring of surface deformation and surface change before, during, and after natural hazards improves decision-making from better forecasts, increased situational awareness, and more informed recovery. However, analyses of InSAR and GPS data sets are currently handcrafted following events and are not generated rapidly and reliably enough for use in operational response to natural disasters. Additionally, the sheer data volumes needed to handle a continuous stream of InSAR data sets also presents a bottleneck. It has been estimated that continuous processing of InSAR coverage of California alone over 3-years would reach PB-scale data volumes. Our Advanced Rapid Imaging and Analysis for Monitoring Hazards (ARIA-MH) science data system enables both science and decision-making communities to monitor areas of interest with derived geodetic data products via seamless data preparation, processing, discovery, and access. We will present our findings on the use of hybrid-cloud computing to improve the timely processing and delivery of geodetic data products, integrating event notifications from USGS to improve the timely processing for response, as well as providing browse results for quick looks with other tools for integrative analysis.

Contribution of GNSS CORS Infrastructure to the Mission of Modern Geodesy and Status of GNSS CORS in Thailand

Directory of Open Access Journals (Sweden)

Chalermchon Satirapod

2011-01-01

Full Text Available Geodesy is the science of measuring and mapping the geometry, orientation and gravity field of the Earth including the associated variations with time. Geodesy has also provided the foundation for high accuracy surveying and mapping. Modern Geodesy involves a range of space and terrestrial technologies that contribute to our knowledge of the solid earth, atmosphere and oceans. These technologies include: Global Positioning System/Global Navigation Satellite Systems (GPS/GNSS, Satellite Laser Ranging (SLR, Very Long Baseline Interferometry (VLBI, Satellite Altimetry, Gravity Mapping Missions such as GRACE, CHAMP and GOCE, satelliteborne Differential Interferometric Synthetic Aperture Radar (DInSAR, Absolute and Relative Gravimetry, and Precise Terrestrial Surveying (Levelling and Traversing. A variety of services have been established in recent years to ensure high accuracy and reliable geodetic products to support geoscientific research. The reference frame defined by Modern Geodesy is now the basis for most national and regional datums. Furthermore, the GPS/GNSS technology is a crucial geopositioning tool for both Geodesy and Surveying. There is therefore a blurring of the distinction between geodetic and surveying GPS/GNSS techniques, and increasingly the ground infrastructure of continuously operating reference stations (CORS receivers attempts to address the needs of both geodesists and other positioning professionals. Yet Geodesy is also striving to increase the level of accuracy by a factor of ten over the next decade in order to address the demands of “global change” studies. The Global Geodetic Observing System (GGOS is an important component of the International Association of Geodesy. GGOS aims to integrate all geodetic observations in order to generate a consistent high quality set of geodetic parameters for monitoring the phenomena and processes within the “System Earth”. Integration implies the inclusion of all relevant

Global Geodesy Using GPS Without Fiducial Sites

Science.gov (United States)

Heflin, Michael B.; Blewitt, Geoffrey

1994-01-01

Global Positioning System, GPS, used to make global geodetic measurements without use of fiducial site coordinates. Baseline lengths and geocentric radii for each site determined without having to fix any site coordinates. Given n globally distributed sites, n baseline lengths and n geocentric radii form polyhedron with each site at vertex and with geocenter at intersection of all radii. Geodetic information derived from structure of polyhedron and its change with time. Approach applied to any global geodetic technique.

Twenty-five years of geodetic measurements along the Tadjoura-Asal rift system, Djibouti, East Africa

Science.gov (United States)

Vigny, Christophe; de Chabalier, Jean-Bernard; Ruegg, Jean-Claude; Huchon, Philippe; Feigl, Kurt L.; Cattin, Rodolphe; Asfaw, Laike; Kanbari, Khaled

2007-06-01

Since most of Tadjoura-Asal rift system sits on dry land in the Afar depression near the triple junction between the Arabia, Somalia, and Nubia plates, it is an ideal natural laboratory for studying rifting processes. We analyze these processes in light of a time series of geodetic measurements from 1978 through 2003. The surveys used triangulation (1973), trilateration (1973, 1979, and 1981-1986), leveling (1973, 1979, 1984-1985, and 2000), and the Global Positioning System (GPS, in 1991, 1993, 1995, 1997, 1999, 2001, and 2003). A network of about 30 GPS sites covers the Republic of Djibouti. Additional points were also measured in Yemen and Ethiopia. Stations lying in the Danakil block have almost the same velocity as Arabian plate, indicating that opening near the southern tip of the Red Sea is almost totally accommodated in the Afar depression. Inside Djibouti, the Asal-Ghoubbet rift system accommodates 16 ± 1 mm/yr of opening perpendicular to the rift axis and exhibits a pronounced asymmetry with essentially null deformation on its southwestern side and significant deformation on its northeastern side. This rate, slightly higher than the large-scale Arabia-Somalia motion (13 ± 1 mm/yr), suggests transient variations associated with relaxation processes following the Asal-Ghoubbet seismovolcanic sequence of 1978. Inside the rift, the deformation pattern exhibits a clear two-dimensional pattern. Along the rift axis, the rate decreases to the northwest, suggesting propagation in the same direction. Perpendicular to the rift axis, the focus of the opening is clearly shifted to the northeast, relative to the topographic rift axis, in the "Petit Rift," a rift-in-rift structure, containing most of the active faults and the seismicity. Vertical motions, measured by differential leveling, show the same asymmetric pattern with a bulge of the northeastern shoulder. Although the inner floor of the rift is subsiding with respect to the shoulders, all sites within the

An accuracy assessment of realtime GNSS time series toward semi- real time seafloor geodetic observation

Science.gov (United States)

Osada, Y.; Ohta, Y.; Demachi, T.; Kido, M.; Fujimoto, H.; Azuma, R.; Hino, R.

2013-12-01

Large interplate earthquake repeatedly occurred in Japan Trench. Recently, the detail crustal deformation revealed by the nation-wide inland GPS network called as GEONET by GSI. However, the maximum displacement region for interplate earthquake is mainly located offshore region. GPS/Acoustic seafloor geodetic observation (hereafter GPS/A) is quite important and useful for understanding of shallower part of the interplate coupling between subducting and overriding plates. We typically conduct GPS/A in specific ocean area based on repeated campaign style using research vessel or buoy. Therefore, we cannot monitor the temporal variation of seafloor crustal deformation in real time. The one of technical issue on real time observation is kinematic GPS analysis because kinematic GPS analysis based on reference and rover data. If the precise kinematic GPS analysis will be possible in the offshore region, it should be promising method for real time GPS/A with USV (Unmanned Surface Vehicle) and a moored buoy. We assessed stability, precision and accuracy of StarFireTM global satellites based augmentation system. We primarily tested for StarFire in the static condition. In order to assess coordinate precision and accuracy, we compared 1Hz StarFire time series and post-processed precise point positioning (PPP) 1Hz time series by GIPSY-OASIS II processing software Ver. 6.1.2 with three difference product types (ultra-rapid, rapid, and final orbits). We also used difference interval clock information (30 and 300 seconds) for the post-processed PPP processing. The standard deviation of real time StarFire time series is less than 30 mm (horizontal components) and 60 mm (vertical component) based on 1 month continuous processing. We also assessed noise spectrum of the estimated time series by StarFire and post-processed GIPSY PPP results. We found that the noise spectrum of StarFire time series is similar pattern with GIPSY-OASIS II processing result based on JPL rapid orbit

Critical Dynamics of the Xy-Model on the One-Dimensional Superlattice by Position Space Renormalization Group

Science.gov (United States)

Lima, J. P. De; Gonçalves, L. L.

The critical dynamics of the isotropic XY-model on the one-dimensional superlattice is considered in the framework of the position space renormalization group theory. The decimation transformation is introduced by considering the equations of motion of the operators associated to the excitations of the system, and it corresponds to an extension of the procedure introduced by Stinchcombe and dos Santos (J. Phys. A18, L597 (1985)) for the homogeneous lattice. The dispersion relation is obtained exactly and the static and dynamic scaling forms are explicitly determined. The dynamic critical exponent is also obtained and it is shown that it is identical to the one of the XY-model on the homogeneous chain.

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

Science.gov (United States)

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.

Position requirements for space station personnel and linkages to portable microcomputer performance assessment

Science.gov (United States)

Jeanneret, P. R.

1988-01-01

The development and use of a menu of performance tests that can be self-administered on a portable microcomputer are investigated. In order to identify, develop, or otherwise select the relevant human capabilities/attributes to measure and hence include in the performance battery, it is essential that an analysis be conducted of the jobs or functions that will be performed throughout a space shuttle mission. The primary job analysis instrument, the Position Analysis Questionnaire (PAQ), is discussed in detail so the reader will have sufficient background for understanding the application of the instrument to the various work activities included within the scope of the study, and the derivation of the human requirements (abilities/attributes) from the PAQ analyses. The research methodology is described and includes the procedures used for gathering the PAQ data. The results are presented in detail with specific emphasis on identifying critical requirements that can be measured with a portable computerized assessment battery. A discussion of the results is given with implications for future research.

The Earth isn't flat: The (large) influence of topography on geodetic fault slip imaging.

Science.gov (United States)

Thompson, T. B.; Meade, B. J.

2017-12-01

While earthquakes both occur near and generate steep topography, most geodetic slip inversions assume that the Earth's surface is flat. We have developed a new boundary element tool, Tectosaur, with the capability to study fault and earthquake problems including complex fault system geometries, topography, material property contrasts, and millions of elements. Using Tectosaur, we study the model error induced by neglecting topography in both idealized synthetic fault models and for the cases of the MW=7.3 Landers and MW=8.0 Wenchuan earthquakes. Near the steepest topography, we find the use of flat Earth dislocation models may induce errors of more than 100% in the inferred slip magnitude and rake. In particular, neglecting topographic effects leads to an inferred shallow slip deficit. Thus, we propose that the shallow slip deficit observed in several earthquakes may be an artefact resulting from the systematic use of elastic dislocation models assuming a flat Earth. Finally, using this study as an example, we emphasize the dangerous potential for forward model errors to be amplified by an order of magnitude in inverse problems.

Geodetic proof of vertical recent movements at the seism generating zone of Acambay, Mexico

Directory of Open Access Journals (Sweden)

Luis Miguel Espinosa-Rodríguez

2016-12-01

Full Text Available The central territorial belt oriented west-east and located along the parallel 19 in the Mexican Republic, is composed of a complex system of faults, that respond to the consequent morphology of a tension arched system, which has been erected to the Volcanic Transmexican or Transversal Belt. This region evidences the dynamics and evolution of a graben and horst tectonic system, as well as volcanic manifestations characterized by stratovolcanoes, monogenetic fields and fisural flows, among others. In particular, in the center of the Mexican regional complex, the fault system which delimits the region of Acambay in the state of Mexico, had showed evidences of seismogenerating activity during a century until the present time. According to the above and based on the geomorphological analysis and the geodetic measurements, the dynamic presented by these morphostructures in a multitemporal comparative study (1998/2003 o 2011 is showed. The rates of vertical tectonic movements reflect recent rise values ranging from + 7,3 to 12,8 mm/year in the northern horst of Santa María Tixmadejé, while in the central graben of Acambay are very weak, of the order of + 0,4 to + 0,5 mm/year.

Geodetic Control Points, Chippewa County has been working on tightening up their control network over the years. The first network was constructed in 1993, with densification done from 2008-2011., Published in 2011, Not Applicable scale, Chippewa County Government.

Data.gov (United States)

NSGIC Local Govt | GIS Inventory — Geodetic Control Points dataset current as of 2011. Chippewa County has been working on tightening up their control network over the years. The first network was...

SIRGAS: the core geodetic infrastructure in Latin America and the Caribbean

Science.gov (United States)

Sanchez, L.; Brunini, C.; Drewes, H.; Mackern, V.; da Silva, A.

2013-05-01

Studying, understanding, and modelling geophysical phenomena, such as global change and geodynamics, require geodetic reference frames with (1) an order of accuracy higher than the magnitude of the effects we want to study, (2) consistency and reliability worldwide (the same accuracy everywhere), and (3) a long-term stability (the same order of accuracy at any time). The definition, realisation, maintenance, and wide-utilisation of the International Terrestrial Reference System (ITRS) are oriented to guarantee a globally unified geometric reference frame with reliability at the mm-level, i.e. the International Terrestrial Reference Frame (ITRF). The densification of the global ITRF in Latin America and The Caribbean is given by SIRGAS (Sistema de Referencia Geocéntrico para Las Américas), primary objective of which is to provide the most precise coordinates in the region. Therefore, SIRGAS is the backbone for all regional projects based on the generation, use, and analysis of geo-referenced data at national as well as at international level. Besides providing the reference for a wide range of scientific applications such as the monitoring of Earth's crust deformations, vertical movements, sea level variations, atmospheric studies, etc., SIRGAS is also the platform for practical applications such as engineering projects, digital administration of geographical data, geospatial data infrastructures, etc. According to this, the present contribution describes the main features of SIRGAS, giving special care to those challenges faced to continue providing the best possible, long-term stable and high-precise reference frame for Latin America and the Caribbean.

Space commerce in a global economy - Comparison of international approaches to commercial space

Science.gov (United States)

Stone, Barbara A.; Kleber, Peter

1992-01-01

A historical perspective, current status, and comparison of national government/commercial space industry relationships in the United States and Europe are presented. It is noted that space technology has been developed and used primarily to meet the needs of civil and military government initiatives. Two future trends of space technology development include new space enterprises, and the national drive to achieve a more competitive global economic position.

Large earthquake rates from geologic, geodetic, and seismological perspectives

Science.gov (United States)

Jackson, D. D.

2017-12-01

Earthquake rate and recurrence information comes primarily from geology, geodesy, and seismology. Geology gives the longest temporal perspective, but it reveals only surface deformation, relatable to earthquakes only with many assumptions. Geodesy is also limited to surface observations, but it detects evidence of the processes leading to earthquakes, again subject to important assumptions. Seismology reveals actual earthquakes, but its history is too short to capture important properties of very large ones. Unfortunately, the ranges of these observation types barely overlap, so that integrating them into a consistent picture adequate to infer future prospects requires a great deal of trust. Perhaps the most important boundary is the temporal one at the beginning of the instrumental seismic era, about a century ago. We have virtually no seismological or geodetic information on large earthquakes before then, and little geological information after. Virtually all-modern forecasts of large earthquakes assume some form of equivalence between tectonic- and seismic moment rates as functions of location, time, and magnitude threshold. That assumption links geology, geodesy, and seismology, but it invokes a host of other assumptions and incurs very significant uncertainties. Questions include temporal behavior of seismic and tectonic moment rates; shape of the earthquake magnitude distribution; upper magnitude limit; scaling between rupture length, width, and displacement; depth dependence of stress coupling; value of crustal rigidity; and relation between faults at depth and their surface fault traces, to name just a few. In this report I'll estimate the quantitative implications for estimating large earthquake rate. Global studies like the GEAR1 project suggest that surface deformation from geology and geodesy best show the geography of very large, rare earthquakes in the long term, while seismological observations of small earthquakes best forecasts moderate earthquakes

Determining astronomical seeing conditions at Matjiesfontein by optical and turbulence methods

Energy Technology Data Exchange (ETDEWEB)

Nickola, M [Hartebeesthoek Radio Astronomy Observatory (HartRAO) Space Geodesy Programme, PO Box 443, Krugersdorp 1740 (South Africa); Esau, I [G.C. Rieber Climate Institute of the Nansen Environmental and Remote Sensing Center (NERSC), Thoermohlensgate 47, N-5006 Bergen (Norway); Djolov, G [University of Pretoria, Department of Geography, Geoinformatics and Meteorology, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria 0002 (South Africa)

2010-08-15

Matjiesfontein in the Karoo has been proposed as a suitable location for a new fundamental space geodetic observatory. On-site geodetic equipment will include a Lunar Laser Ranger (LLR). LLR requires sub-arcsecond optical seeing conditions for delivery of high quality and quantity data. Seeing conditions at the Matjiesfontein site will be evaluated by making use of an automated seeing monitor and by modelling atmospheric turbulence with Large Eddy Simulation Nansen Center Improved Code (LESNIC).

CDDIS_VLBI_products_positions

Data.gov (United States)

National Aeronautics and Space Administration — Station positions and velocity solutions in Software INdependent EXchange (SINEX) format derived from analysis of Very Long Baseline Interferometry (VLBI) data....

Research Article. Geodesic equations and their numerical solutions in geodetic and Cartesian coordinates on an oblate spheroid

Directory of Open Access Journals (Sweden)

Panou G.

2017-02-01

Full Text Available The direct geodesic problem on an oblate spheroid is described as an initial value problem and is solved numerically using both geodetic and Cartesian coordinates. The geodesic equations are formulated by means of the theory of differential geometry. The initial value problem under consideration is reduced to a system of first-order ordinary differential equations, which is solved using a numerical method. The solution provides the coordinates and the azimuths at any point along the geodesic. The Clairaut constant is not used for the solution but it is computed, allowing to check the precision of the method. An extensive data set of geodesics is used, in order to evaluate the performance of the method in each coordinate system. The results for the direct geodesic problem are validated by comparison to Karney’s method. We conclude that a complete, stable, precise, accurate and fast solution of the problem in Cartesian coordinates is accomplished.

A novel method for estimating the initial rotor position of PM motors without the position sensor

International Nuclear Information System (INIS)

Rostami, Alireza; Asaei, Behzad

2009-01-01

Permanent magnet (PM) motors have been used widely in the industrial applications. However, a need of the position sensor is a drawback of their control system. The sensorless methods using the back-EMF (electromotive force) cannot detect the rotor position at a standstill; recently, a few methods proposed to detect the initial rotor position, but they have high estimation error which reduces starting torque of the motor. Therefore, in this paper, a novel method to detect the initial rotor position of the PM motors is proposed, first, by using a space vector model, response of the stator current space vector to the saturation of the stator core is analyzed; then a novel method based on the saturation effect is presented that estimates the initial rotor position and the maximum estimation error is less than 3.8 deg. Simulation results confirm this method is effective and precise, and variation of the motor parameters does not affect its precision.

A novel method for estimating the initial rotor position of PM motors without the position sensor

Energy Technology Data Exchange (ETDEWEB)

Rostami, Alireza; Asaei, Behzad [School of Electrical and Computer Engineering, Faculty of Engineering, University of Tehran, Tehran (Iran)

2009-08-15

Permanent magnet (PM) motors have been used widely in the industrial applications. However, a need of the position sensor is a drawback of their control system. The sensorless methods using the back-EMF (electromotive force) cannot detect the rotor position at a standstill; recently, a few methods proposed to detect the initial rotor position, but they have high estimation error which reduces starting torque of the motor. Therefore, in this paper, a novel method to detect the initial rotor position of the PM motors is proposed, first, by using a space vector model, response of the stator current space vector to the saturation of the stator core is analyzed; then a novel method based on the saturation effect is presented that estimates the initial rotor position and the maximum estimation error is less than 3.8. Simulation results confirm this method is effective and precise, and variation of the motor parameters does not affect its precision. (author)

Geodetic parametrisation of the CNGS project

International Nuclear Information System (INIS)

Jones, Mark; Mayoud, Michel; Wiart, Aude

2003-01-01

The CNGS (CERN Neutrinos to Gran Sasso) project aims to investigate the oscillation' of neutrinos. A beam extracted from the CERN SPS accelerator will produce a beam consisting uniquely of muon-type neutrinos that will be directed underground to their destination, the Gran Sasso National Laboratory (LNGS) in Italy, 730 km from CERN. For the CNGS project it is evident that our knowledge of the relative position of the two Laboratories, indeed the relative position of the neutrino target at CERN and the detector at Gran Sasso, is essential. Up until the CNGS Project the position of the CERN accelerators on a global scale has not been critical. Two GPS campaigns carried out in 1998, have now resolved this question to a high degree of accuracy, and a GPS survey campaign at Gran Sasso has provided us with the relative position. The parameters for the civil engineering work that started in September 2000 are all based upon the information from these two GPS campaigns. However, consultation with the national surveying bodies in France (IGN) and Switzerland (OFT) showed that the geoid model used for the LEP would probably need to be updated for the alignment of the CNGS accelerator components. Based upon the 1998 Swiss geoid model (CHGEO98) a new model of the geoid and technique for its exploitation has been implemented at CERN (CG2000). The parameters establishing the position of the CERN Laboratory together with those of the CNGS beam line have now been refined again. This new geoid model is currently being incorporated into our various algorithms. (author)

Short-Term and Long-Term Forecasting for the 3D Point Position Changing by Using Artificial Neural Networks

Directory of Open Access Journals (Sweden)

Eleni-Georgia Alevizakou

2018-03-01

Full Text Available Forecasting is one of the most growing areas in most sciences attracting the attention of many researchers for more extensive study. Therefore, the goal of this study is to develop an integrated forecasting methodology based on an Artificial Neural Network (ANN, which is a modern and attractive intelligent technique. The final result is to provide short-term and long-term forecasts for point position changing, i.e., the displacement or deformation of the surface they belong to. The motivation was the combination of two thoughts, the insertion of the forecasting concept in Geodesy as in the most scientific disciplines (e.g., Economics, Medicine and the desire to know the future position of any point on a construction or on the earth’s crustal. This methodology was designed to be accurate, stable and general for different kind of geodetic data. The basic procedure consists of the definition of the forecasting problem, the preliminary data analysis (data pre-processing, the definition of the most suitable ANN, its evaluation using the proper criteria and finally the production of forecasts. The methodology gives particular emphasis on the stages of the pre-processing and the evaluation. Additionally, the importance of the prediction intervals (PI is emphasized. A case study, which includes geodetic data from the year 2003 to the year 2016—namely X, Y, Z coordinates—is implemented. The data were acquired by 1000 permanent Global Navigation Satellite System (GNSS stations. During this case study, 2016 ANNs—with different hyper-parameters—are trained and tested for short-term forecasting and 2016 for long-term forecasting, for each of the GNSS stations. In addition, other conventional statistical forecasting methods are used for the same purpose using the same data set. Finally the most appropriate Non-linear Autoregressive Recurrent network (NAR or Non-linear Autoregressive with eXogenous inputs (NARX for the forecasting of 3D point

FSH: fast spaced seed hashing exploiting adjacent hashes.

Science.gov (United States)

Girotto, Samuele; Comin, Matteo; Pizzi, Cinzia

2018-01-01

Patterns with wildcards in specified positions, namely spaced seeds , are increasingly used instead of k -mers in many bioinformatics applications that require indexing, querying and rapid similarity search, as they can provide better sensitivity. Many of these applications require to compute the hashing of each position in the input sequences with respect to the given spaced seed, or to multiple spaced seeds. While the hashing of k -mers can be rapidly computed by exploiting the large overlap between consecutive k -mers, spaced seeds hashing is usually computed from scratch for each position in the input sequence, thus resulting in slower processing. The method proposed in this paper, fast spaced-seed hashing (FSH), exploits the similarity of the hash values of spaced seeds computed at adjacent positions in the input sequence. In our experiments we compute the hash for each positions of metagenomics reads from several datasets, with respect to different spaced seeds. We also propose a generalized version of the algorithm for the simultaneous computation of multiple spaced seeds hashing. In the experiments, our algorithm can compute the hashing values of spaced seeds with a speedup, with respect to the traditional approach, between 1.6[Formula: see text] to 5.3[Formula: see text], depending on the structure of the spaced seed. Spaced seed hashing is a routine task for several bioinformatics application. FSH allows to perform this task efficiently and raise the question of whether other hashing can be exploited to further improve the speed up. This has the potential of major impact in the field, making spaced seed applications not only accurate, but also faster and more efficient. The software FSH is freely available for academic use at: https://bitbucket.org/samu661/fsh/overview.

Inversion of the Earth spherical albedo from radiation-pressure

Science.gov (United States)

Wilkman, Olli; Herranen, Joonas; Näränen, Jyri; Virtanen, Jenni; Koivula, Hannu; Poutanen, Markku; Penttilä, Antti; Gritsevich, Maria; Muinonen, Karri

2017-04-01

We are studying the retrieval of the spherical albedo and net radiation of the Earth from the perturbations caused by the planet's radiation on the dynamics of its satellites. The spherical or Bond albedo gives the ratio of the fluxes incident on and scattered by the planet. The net radiation represents the net heat input into the planet's climate system and drives changes in its atmospheric, surface, and ocean temperatures. The ultimate aim of the study is inverting the problem and estimating the Earth albedo based on observations of satellites, simultaneously improving the space-geodetic positioning accuracy. Here we investigate the effect of the spherical albedo on satellite orbits with the help of a simplified model. We simulate the propagation of satellite orbits using a new simulation software. The simulation contains the main perturbing forces on medium and high Earth orbits, used by, e.g., navigation satellites, including the radiation pressure of reflected sunlight from the Earth. An arbitrary satellite shape model can be used, and the rotation of the satellite is modeled. In this first study, we use a box-wing satellite model with a simple surface BRDF. We also assume a diffusely reflecting Earth with a single global albedo value. We vary the Earth albedo and search for systematic effects on different orbits. Thereafter, we estimate the dependence of the albedo accuracy on the satellite positioning and timing data available. We show that the inversion of the spherical albedo with reasonable accuracy is feasible from the current space-geodetic measurements.

Applications of Voronoi and Delaunay Diagrams in the solution of the geodetic boundary value problem

Directory of Open Access Journals (Sweden)

C. A. B. Quintero

Full Text Available Voronoi and Delaunay structures are presented as discretization tools to be used in numerical surface integration aiming the computation of geodetic problems solutions, when under the integral there is a non-analytical function (e. g., gravity anomaly and height. In the Voronoi approach, the target area is partitioned into polygons which contain the observed point and no interpolation is necessary, only the original data is used. In the Delaunay approach, the observed points are vertices of triangular cells and the value for a cell is interpolated for its barycenter. If the amount and distribution of the observed points are adequate, gridding operation is not required and the numerical surface integration is carried out by point-wise. Even when the amount and distribution of the observed points are not enough, the structures of Voronoi and Delaunay can combine grid with observed points in order to preserve the integrity of the original information. Both schemes are applied to the computation of the Stokes' integral, the terrain correction, the indirect effect and the gradient of the gravity anomaly, in the State of Rio de Janeiro, Brazil area.

Deformation analysis of the repeated positional surveys in the undermined localities using web applications and WMS map services

Directory of Open Access Journals (Sweden)

Milan Talich

2007-06-01

Full Text Available The XML web application for on-line calculations of deformation analysis from the repeated positional surveys using Internet service and data is described. Parameters of deformation field (strain tensors, total dilatations are determined in a grid network covering the zone of interest. Displacement vectors from repeated measurements at given points of a geodetic network represent the imput data of calculation. The calculation is based on application of the theory of continuum mechanics and its fundamental prerequisite is homogeneity of the researched territory.The application currently utilizes the Web Map Services - WMS for the graphic presentation of calculated results as GIS. This service for example enables on-line thematic map composition as defined by the user in the window of Internet explorer based on data given by servers of WMS service. Thus the user does not need to own any geographic data to create his/her GIS.Furthermore there are also given application examples of the repeated geodetic surveys used in the field at localities in the forefront of ČSA giant quarry at Komořany and in the undermined territory in Ostrava region. The examples show the independence of calculated values of tensors from rotation and translation of the coordinate systems in practise. This fact gives the evidence that the deformation analysis is more objective dynamic indicator in the researched area and not only the calculus and representation of point displacement vectors. After registration this application is at all interested persons disposal to on-line calculations via the Internet.

States in the Hilbert space formulation and in the phase space formulation of quantum mechanics

International Nuclear Information System (INIS)

Tosiek, J.; Brzykcy, P.

2013-01-01

We consider the problem of testing whether a given matrix in the Hilbert space formulation of quantum mechanics or a function considered in the phase space formulation of quantum theory represents a quantum state. We propose several practical criteria for recognising states in these two versions of quantum physics. After minor modifications, they can be applied to check positivity of any operators acting in a Hilbert space or positivity of any functions from an algebra with a ∗-product of Weyl type. -- Highlights: ► Methods of testing whether a given matrix represents a quantum state. ► The Stratonovich–Weyl correspondence on an arbitrary symplectic manifold. ► Criteria for checking whether a function on a symplectic space is a Wigner function

Gravitational instantons in H-spaces

International Nuclear Information System (INIS)

Hacyan, S.

1979-01-01

A spin coefficient method valid for spaces with positive definite metric is presented, together with a Petrov-Penrosetype classification. The theory of H-spaces is applied to self-dual gravitational instantons. (orig.)

Position space analysis of the AdS (in)stability problem

NARCIS (Netherlands)

Dimitrakopoulos, F.V.; Freivogel, B.; Lippert, M.; Yang, I.S.

2015-01-01

We investigate whether arbitrarily small perturbations in global AdS space are generically unstable and collapse into black holes on the time scale set by gravitational interactions. We argue that current evidence, combined with our analysis, strongly suggests that a set of nonzero measure in the

Smart Device-Supported BDS/GNSS Real-Time Kinematic Positioning for Sub-Meter-Level Accuracy in Urban Location-Based Services.

Science.gov (United States)

Wang, Liang; Li, Zishen; Zhao, Jiaojiao; Zhou, Kai; Wang, Zhiyu; Yuan, Hong

2016-12-21

Using mobile smart devices to provide urban location-based services (LBS) with sub-meter-level accuracy (around 0.5 m) is a major application field for future global navigation satellite system (GNSS) development. Real-time kinematic (RTK) positioning, which is a widely used GNSS-based positioning approach, can improve the accuracy from about 10-20 m (achieved by the standard positioning services) to about 3-5 cm based on the geodetic receivers. In using the smart devices to achieve positioning with sub-meter-level accuracy, a feasible solution of combining the low-cost GNSS module and the smart device is proposed in this work and a user-side GNSS RTK positioning software was developed from scratch based on the Android platform. Its real-time positioning performance was validated by BeiDou Navigation Satellite System/Global Positioning System (BDS/GPS) combined RTK positioning under the conditions of a static and kinematic (the velocity of the rover was 50-80 km/h) mode in a real urban environment with a SAMSUNG Galaxy A7 smartphone. The results show that the fixed-rates of ambiguity resolution (the proportion of epochs of ambiguities fixed) for BDS/GPS combined RTK in the static and kinematic tests were about 97% and 90%, respectively, and the average positioning accuracies (RMS) were better than 0.15 m (horizontal) and 0.25 m (vertical) for the static test, and 0.30 m (horizontal) and 0.45 m (vertical) for the kinematic test.

Weighted Differentiation Composition Operator from Logarithmic Bloch Spaces to Zygmund-Type Spaces

Directory of Open Access Journals (Sweden)

Huiying Qu

2014-01-01

Full Text Available Let H( denote the space of all holomorphic functions on the unit disk of ℂ, u∈H( and let  n be a positive integer, φ a holomorphic self-map of , and μ a weight. In this paper, we investigate the boundedness and compactness of a weighted differentiation composition operator φ,unf(z=u(zf(n(φ(z,f∈H(, from the logarithmic Bloch spaces to the Zygmund-type spaces.

FAST INTEGER AMBIGUITY RESOLUTION IN GPS KINEMATIC POSITIONING USING LEFT NULL SPACE AND MULTI-TIME (INVERSE PAIRED CHOLESKY DECORRELATION

Directory of Open Access Journals (Sweden)

Rong Duan

Full Text Available Aiming at the problems that huge amount of computation in ambiguity resolution with multiple epochs and high-order matrix inversion occurred in the GPS kinematic relative positioning, a modified algorithm for fast integer ambiguity resolution is proposed. Firstly, Singular Value Decomposition (SVD is applied to construct the left null space matrix in order to eliminate the baselines components, which is able to separate ambiguity parameters from the position parameters efficiently. Kalman filter is applied only to estimate the ambiguity parameters so that the real-time ambiguity float solution is obtained. Then, sorting and multi-time (inverse paired Cholesky decomposition are adopted for decorrelation of ambiguity. After diagonal elements preprocessing and diagonal elements sorting according to the results of Cholesky decomposition, the efficiency of decomposition and decorrelation is improved. Lastly, the integer search algorithm implemented in LAMBDA method is used for searching the integer ambiguity. To verify the validity and efficacy of the proposed algorithm, static and kinematic tests are carried out. Experimental results show that this algorithm has good performance of decorrelation and precision of float solution, with computation speed also increased effectively. The final positioning accuracy result with static baseline error less than 1 cm and kinematic error less than 2 cm, which indicates that it can be used for fast kinematic positioning of high precision carrier.

Bistable Mechanisms for Space Applications.

Science.gov (United States)

Zirbel, Shannon A; Tolman, Kyler A; Trease, Brian P; Howell, Larry L

2016-01-01

Compliant bistable mechanisms are monolithic devices with two stable equilibrium positions separated by an unstable equilibrium position. They show promise in space applications as nonexplosive release mechanisms in deployment systems, thereby eliminating friction and improving the reliability and precision of those mechanical devices. This paper presents both analytical and numerical models that are used to predict bistable behavior and can be used to create bistable mechanisms in materials not previously feasible for compliant mechanisms. Materials compatible with space applications are evaluated for use as bistable mechanisms and prototypes are fabricated in three different materials. Pin-puller and cutter release mechanisms are proposed as potential space applications.

Frictionless segmented mechanics for controlled space closure

OpenAIRE

Andrade Jr, Ildeu

2017-01-01

ABSTRACT Extraction spaces may be needed to achieve specific orthodontic goals of positioning the dentition in harmony with the craniofacial complex. However, the fundamental reality that determines the occlusion final position is the control exerted by the orthodontist while closing the extraction spaces. A specific treatment objective may require the posterior teeth to remain in a constant position anteroposteriorly as well as vertically, while the anterior teeth occupy the entire extractio...

Position of cytogenetic examination of cosmonauts for the space radiation exposure estimate

Science.gov (United States)

Snigiryova, Galina; Novitskaya, Natalia; Fedorenko, Boris

The cytogenetic monitoring was carried out to evaluate of radiation induced stable and un-stable chromosome aberration frequency in peripheral blood lymphocytes of cosmonauts who participated in flights on Mir Orbital Station and ISS (International Space Station). In the period of 1992 -2008 chromosome aberrations in 202 blood samples from 48 cosmonauts were analyzed using the conventional method. In addition 23 blood samples from 12 cosmonauts were analyzed using FISH (fluorescence in situ hybridization) technique. Whole chromosome painting probes for chromosomes 1, 4 and 12 were used simultaneously with a pancentromeric probe. Samples taken before and after the flights were analyzed. Long-term space flights led to an increase of stable (FISH method) and unstable (conventional method) chromosome aber-ration frequencies. The frequencies of dicentrics and centric rings depend on the space flight duration and accumulated dose value. Extravehicular activity also adds to chromosome aber-ration frequency in blood lymphocytes of cosmonauts. Several years after the space flight the increased level of unstable chromosome aberrations is still apparent. The radiation load was decreased for cosmonauts after taking ISS over from MIR station. The cytogenetic results were in agreement with data of physical dosimetry. The dose interval after the first flight, estimated by the frequency of dicentrics, was 113-227 mSv for long-term flights (73 -199 days) and 53-107 mSv for short-term flights (1 -21 days). According to the frequency of FISH translocations, the average dose after the first long-term flight was 186 mSv, which is comparable with estimates made from the dicentric assay. Cytogenetic examination of cosmonauts, including analysis of dicentrics (conventional method) and translocations (FISH method) should find wider applica-tion to assessment of radiation effects associated with long-term space flights such as flights to Mars.

Disintegration of positive isometric group representations on L^p-spaces

NARCIS (Netherlands)

Jeu, de M.F.E.; Rozendaal, J.

2017-01-01

Let G be a Polish locally compact group acting on a Polish space X" role="presentation">X with a G-invariant probability measure μ" role="presentation">μ. We factorize the integral with respect to μ" role="presentation">μ in terms of the integrals with respect to the ergodic measures on X, and show

The Crustal Dynamics Data Information System: A Resource to Support Scientific Analysis Using Space Geodesy

Science.gov (United States)

Noll. Carey E.

2010-01-01

Since 1982. the Crustal Dynamics Data Information System (CDDIS) has supported the archive and distribution of geodetic data products acquired by the National Aeronautics and Space Administration (NASA) as well as national and international programs. The CDDIS provides easy, timely, and reliable access to a variety of data sets, products, and information about these data. These measurements. obtained from a global network of nearly 650 instruments at more than 400 distinct sites, include DORIS (Doppler Orbitography and Radiopositioning Integrated by Satellite), GNSS (Global Navigation Satellite System), SLR and LLR (Satellite and Lunar Laser Ranging), and VLBI (Very Long Baseline Interferometry). The CDDIS data system and its archive have become increasingly important to many national and international science communities, particularly several of the operational services within the International Association of Geodesy (IAG) and its observing system the Global Geodetic Observing System (GGOS), including the International DORIS Service (IDS), the International GNSS Service (IGS). the International Laser Ranging Service (ILRS), the International VLBI Service for Geodesy and Astrometry (IVS). and the International Earth rotation and Reference frame Service (IERS), Investigations resulting from the data and products available through the CDDIS support research in many aspects of Earth system science and global change. Each month, the CDDIS archives more than one million data and derived product files totaling over 90 Gbytes in volume. In turn. the global user community downloads nearly 1.2 TBytes (over 10.5 million files) of data and products from the CDDIS each month. The requirements of analysts have evolved since the start of the CDDIS; the specialized nature of the system accommodates the enhancements required to support diverse data sets and user needs. This paper discusses the CDDIS. including background information about the system and its. user communities

14 CFR 31.65 - Position lights.

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Position lights. 31.65 Section 31.65 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS...; and z is not greater than 0.002. (2) Aviation white— x is not less than 0.300 and not greater than 0...

An Inequality Constrained Least-Squares Approach as an Alternative Estimation Procedure for Atmospheric Parameters from VLBI Observations

Science.gov (United States)

Halsig, Sebastian; Artz, Thomas; Iddink, Andreas; Nothnagel, Axel

2016-12-01

On its way through the atmosphere, radio signals are delayed and affected by bending and attenuation effects relative to a theoretical path in vacuum. In particular, the neutral part of the atmosphere contributes considerably to the error budget of space-geodetic observations. At the same time, space-geodetic techniques become more and more important in the understanding of the Earth's atmosphere, because atmospheric parameters can be linked to the water vapor content in the atmosphere. The tropospheric delay is usually taken into account by applying an adequate model for the hydrostatic component and by additionally estimating zenith wet delays for the highly variable wet component. Sometimes, the Ordinary Least Squares (OLS) approach leads to negative estimates, which would be equivalent to negative water vapor in the atmosphere and does, of course, not reflect meteorological and physical conditions in a plausible way. To cope with this phenomenon, we introduce an Inequality Constrained Least Squares (ICLS) method from the field of convex optimization and use inequality constraints to force the tropospheric parameters to be non-negative allowing for a more realistic tropospheric parameter estimation in a meteorological sense. Because deficiencies in the a priori hydrostatic modeling are almost fully compensated by the tropospheric estimates, the ICLS approach urgently requires suitable a priori hydrostatic delays. In this paper, we briefly describe the ICLS method and validate its impact with regard to station positions.

Integration of the Shuttle RMS/CBM Positioning Virtual Environment Simulation

Science.gov (United States)

Dumas, Joseph D.

1996-01-01

Constructing the International Space Station, or other structures, in space presents a number of problems. In particular, payload restrictions for the Space Shuttle and other launch mechanisms prohibit assembly of large space-based structures on Earth. Instead, a number of smaller modules must be boosted into orbit separately and then assembled to form the final structure. The assembly process is difficult, as docking interfaces such as Common Berthing Mechanisms (CBMS) must be precisely positioned relative to each other to be within the "capture envelope" (approximately +/- 1 inch and +/- 0.3 degrees from the nominal position) and attach properly. In the case of the Space Station, the docking mechanisms are to be positioned robotically by an astronaut using the 55-foot-long Remote Manipulator System (RMS) robot arm. Unfortunately, direct visual or video observation of the placement process is difficult or impossible in many scenarios. One method that has been tested for aligning the CBMs uses a boresighted camera mounted on one CBM to view a standard target on the opposing CBM. While this method might be sufficient to achieve proper positioning with considerable effort, it does not provide a high level of confidence that the mechanisms have been placed within capture range of each other. It also does nothing to address the risk of inadvertent contact between the CBMS, which could result in RMS control software errors. In general, constraining the operator to a single viewpoint with few, if any, depth cues makes the task much more difficult than it would be if the target could be viewed in three-dimensional space from various viewpoints. The actual work area could be viewed by an astronaut during EVA; however, it would be extremely impractical to have an astronaut control the RMS while spacewalking. On the other hand, a view of the RMS and CBMs to be positioned in a virtual environment aboard the Space Shuttle orbiter or Space Station could provide similar benefits

Employing Tropospheric Numerical Weather Prediction Model for High-Precision GNSS Positioning

Science.gov (United States)

Alves, Daniele; Gouveia, Tayna; Abreu, Pedro; Magário, Jackes

2014-05-01

In the past few years is increasing the necessity of realizing high accuracy positioning. In this sense, the spatial technologies have being widely used. The GNSS (Global Navigation Satellite System) has revolutionized the geodetic positioning activities. Among the existent methods one can emphasize the Precise Point Positioning (PPP) and network-based positioning. But, to get high accuracy employing these methods, mainly in real time, is indispensable to realize the atmospheric modeling (ionosphere and troposphere) accordingly. Related to troposphere, there are the empirical models (for example Saastamoinen and Hopfield). But when highly accuracy results (error of few centimeters) are desired, maybe these models are not appropriated to the Brazilian reality. In order to minimize this limitation arises the NWP (Numerical Weather Prediction) models. In Brazil the CPTEC/INPE (Center for Weather Prediction and Climate Studies / Brazilian Institute for Spatial Researches) provides a regional NWP model, currently used to produce Zenithal Tropospheric Delay (ZTD) predictions (http://satelite.cptec.inpe.br/zenital/). The actual version, called eta15km model, has a spatial resolution of 15 km and temporal resolution of 3 hours. In this paper the main goal is to accomplish experiments and analysis concerning the use of troposphere NWP model (eta15km model) in PPP and network-based positioning. Concerning PPP it was used data from dozens of stations over the Brazilian territory, including Amazon forest. The results obtained with NWP model were compared with Hopfield one. NWP model presented the best results in all experiments. Related to network-based positioning it was used data from GNSS/SP Network in São Paulo State, Brazil. This network presents the best configuration in the country to realize this kind of positioning. Actually the network is composed by twenty stations (http://www.fct.unesp.br/#!/pesquisa/grupos-de-estudo-e-pesquisa/gege//gnss-sp-network2789/). The

GLAS/ICESat L2 Global Land Surface Altimetry Data V033

Data.gov (United States)

National Aeronautics and Space Administration — GLA14 contains the land elevation and elevation distribution corrected for geodetic and atmospheric affects calculated from algorithms fine-tuned for over land...

GLAS/ICESat L2 Global Land Surface Altimetry Data (HDF5) V034

Data.gov (United States)

National Aeronautics and Space Administration — GLAH14 contains the land elevation and elevation distribution corrected for geodetic and atmospheric affects calculated from algorithms fine-tuned for over land...

Reflection Positive Stochastic Processes Indexed by Lie Groups

Science.gov (United States)

Jorgensen, Palle E. T.; Neeb, Karl-Hermann; Ólafsson, Gestur

2016-06-01

Reflection positivity originates from one of the Osterwalder-Schrader axioms for constructive quantum field theory. It serves as a bridge between euclidean and relativistic quantum field theory. In mathematics, more specifically, in representation theory, it is related to the Cartan duality of symmetric Lie groups (Lie groups with an involution) and results in a transformation of a unitary representation of a symmetric Lie group to a unitary representation of its Cartan dual. In this article we continue our investigation of representation theoretic aspects of reflection positivity by discussing reflection positive Markov processes indexed by Lie groups, measures on path spaces, and invariant gaussian measures in spaces of distribution vectors. This provides new constructions of reflection positive unitary representations.

Space engineering

Science.gov (United States)

Alexander, Harold L.

1991-01-01

Human productivity was studied for extravehicular tasks performed in microgravity, particularly including in-space assembly of truss structures and other large objects. Human factors research probed the anthropometric constraints imposed on microgravity task performance and the associated workstation design requirements. Anthropometric experiments included reach envelope tests conducted using the 3-D Acoustic Positioning System (3DAPS), which permitted measuring the range of reach possible for persons using foot restraints in neutral buoyancy, both with and without space suits. Much neutral buoyancy research was conducted using the support of water to simulate the weightlessness environment of space. It became clear over time that the anticipated EVA requirement associated with the Space Station and with in-space construction of interplanetary probes would heavily burden astronauts, and remotely operated robots (teleoperators) were increasingly considered to absorb the workload. Experience in human EVA productivity led naturally to teleoperation research into the remote performance of tasks through human controlled robots.

Lunar Topography: Results from the Lunar Orbiter Laser Altimeter

Science.gov (United States)

Neumann, Gregory; Smith, David E.; Zuber, Maria T.; Mazarico, Erwan

2012-01-01

The Lunar Orbiter Laser Altimeter (LOLA) onboard the Lunar Reconnaissance Orbiter (LRO) has been operating nearly continuously since July 2009, accumulating over 6 billion measurements from more than 2 billion in-orbit laser shots. LRO's near-polar orbit results in very high data density in the immediate vicinity of the lunar poles, with full coverage at the equator from more than 12000 orbital tracks averaging less than 1 km in spacing at the equator. LRO has obtained a global geodetic model of the lunar topography with 50-meter horizontal and 1-m radial accuracy in a lunar center-of-mass coordinate system, with profiles of topography at 20-m horizontal resolution, and 0.1-m vertical precision. LOLA also provides measurements of reflectivity and surface roughness down to its 5-m laser spot size. With these data LOLA has measured the shape of all lunar craters 20 km and larger. In the proposed extended mission commencing late in 2012, LOLA will concentrate observations in the Southern Hemisphere, improving the density of the polar coverage to nearly 10-m pixel resolution and accuracy to better than 20 m total position error. Uses for these data include mission planning and targeting, illumination studies, geodetic control of images, as well as lunar geology and geophysics. Further improvements in geodetic accuracy are anticipated from the use of re ned gravity fields after the successful completion of the Gravity Recovery and Interior Laboratory (GRAIL) mission in 2012.

High-accuracy local positioning network for the alignment of the Mu2e experiment.

Energy Technology Data Exchange (ETDEWEB)

Hejdukova, Jana B. [Czech Technical Univ., Prague (Czech Republic)

2017-06-01

This Diploma thesis describes the establishment of a high-precision local positioning network and accelerator alignment for the Mu2e physics experiment. The process of establishing new network consists of few steps: design of the network, pre-analysis, installation works, measurements of the network and making adjustments. Adjustments were performed using two approaches. First is a geodetic approach of taking into account the Earth’s curvature and the metrological approach of a pure 3D Cartesian system on the other side. The comparison of those two approaches is performed and evaluated in the results and compared with expected differences. The effect of the Earth’s curvature was found to be significant for this kind of network and should not be neglected. The measurements were obtained with Absolute Tracker AT401, leveling instrument Leica DNA03 and gyrotheodolite DMT Gyromat 2000. The coordinates of the points of the reference network were determined by the Least Square Meth od and the overall view is attached as Annexes.

Facilitating open global data use in earthquake source modelling to improve geodetic and seismological approaches

Science.gov (United States)

Sudhaus, Henriette; Heimann, Sebastian; Steinberg, Andreas; Isken, Marius; Vasyura-Bathke, Hannes

2017-04-01

In the last few years impressive achievements have been made in improving inferences about earthquake sources by using InSAR (Interferometric Synthetic Aperture Radar) data. Several factors aided these developments. The open data basis of earthquake observations has expanded vastly with the two powerful Sentinel-1 SAR sensors up in space. Increasing computer power allows processing of large data sets for more detailed source models. Moreover, data inversion approaches for earthquake source inferences are becoming more advanced. By now data error propagation is widely implemented and the estimation of model uncertainties is a regular feature of reported optimum earthquake source models. Also, more regularly InSAR-derived surface displacements and seismological waveforms are combined, which requires finite rupture models instead of point-source approximations and layered medium models instead of homogeneous half-spaces. In other words the disciplinary differences in geodetic and seismological earthquake source modelling shrink towards common source-medium descriptions and a source near-field/far-field data point of view. We explore and facilitate the combination of InSAR-derived near-field static surface displacement maps and dynamic far-field seismological waveform data for global earthquake source inferences. We join in the community efforts with the particular goal to improve crustal earthquake source inferences in generally not well instrumented areas, where often only the global backbone observations of earthquakes are available provided by seismological broadband sensor networks and, since recently, by Sentinel-1 SAR acquisitions. We present our work on modelling standards for the combination of static and dynamic surface displacements in the source's near-field and far-field, e.g. on data and prediction error estimations as well as model uncertainty estimation. Rectangular dislocations and moment-tensor point sources are exchanged by simple planar finite

Glacier Mass Changes of Lake-Terminating Grey and Tyndall Glaciers at the Southern Patagonia Icefield Derived From Geodetic Observations and Energy and Mass Balance Modeling

Directory of Open Access Journals (Sweden)

Stephanie S. Weidemann

2018-06-01

Full Text Available In this study we demonstrate how energy and mass fluxes vary in space and time for Grey and Tyndall glaciers at the Southern Patagonia Icefield (SPI. Despite the overall glacier retreat of most Patagonian glaciers, a recent increase in mass loss has been observed, but individual glaciers respond differently in terms of spatial and temporal changes. In this context, the detailed investigation of the effect of mass balance processes on recent glacier response to climate forcing still needs refinement. We therefore quantify surface energy-fluxes and climatic mass balance of the two neighboring glaciers, Grey and Tyndall. The COupled Snow and Ice energy and MAss balance model COSIMA is applied to assess recent surface energy and climatic mass balance variability with a high temporal and spatial resolution for a 16-year period between April 2000 and March 2016. The model is driven by downscaled 6-hourly atmospheric data derived from ERA-Interim reanalysis and MODIS/Terra Snow Cover and validated against ablation measurements made in single years. High resolution precipitation fields are determined by using an analytical orographic precipitation model. Frontal ablation is estimated as residual of climatic mass balance and geodetic mass balance derived from TanDEM-X/SRTM between 2000 and 2014. We simulate a positive glacier-wide mean annual climatic mass balance of +1.02 ± 0.52 m w.e. a−1 for Grey Glacier and of +0.68 ± 0.54 m w.e. a−1 for Tyndall Glacier between 2000 and 2014. Climatic mass balance results show a high year to year variability. Comparing climatic mass balance results with previous studies underlines the high uncertainty in climatic mass balance modeling with respect to accumulation on the SPI. Due to the lack of observations accumulation estimates differ from previous studies based on the methodological approaches. Mean annual ice loss by frontal ablation is estimated to be 2.07 ± 0.70 m w.e. a−1 for Grey Glacier and 3.26 ± 0

GLAS/ICESat L2 Ocean Altimetry Data V033

Data.gov (United States)

National Aeronautics and Space Administration — GLA15 contains the ocean elevation and small-scale roughness corrected for geodetic and atmospheric affects, calculated from algorithms fine-tuned for ocean returns....

Map projections cartographic information systems

CERN Document Server

Grafarend, Erik W; Syffus, Rainer

2014-01-01

This book offers a timely review of map projections including sphere, ellipsoid, rotational surfaces, and geodetic datum transformations. Coverage includes computer vision, and remote sensing space projective mappings in photogrammetry.

The crustal velocity field mosaic of the Alpine Mediterranean area (Italy): Insights from new geodetic data

Science.gov (United States)

Farolfi, Gregorio; Del Ventisette, Chiara

2016-04-01

A new horizontal crustal velocity field of Alpine Mediterranean area was determined by continuous long time series (6.5 years) of 113 Global Navigation Satellite System (GNSS) permanent stations. The processing was performed using state-of-the-art absolute antenna phase center correction model and recomputed precise IGS orbits available since April 2014. Moreover, a new more accurate tropospheric mapping function for geodetic applications was adopted. Results provide a new detailed map of the kinematics throughout the entire study area. This area is characterized by a complex tectonic setting driven by the interaction of Eurasian and African plates. The eastern Alps, Corsica, Sardinia and the Tyrrhenian Sea (which is covered only by interpolation data) show small velocity residuals with respect to the Eurasian plate. The whole Apennines axis discriminates two different velocity patterns, the Adriatic and the Tyrrhenian area. The area around Messina Strait, which separates peninsular Italy and Sicily, represents a poorly understood region. Results identify an important boundary zone between two different domains, Calabria and Sicily, which are characterized by different crustal motions. The northeastern part of Sicily and Calabria move like Adriatic area, whilst the rest of Sicily, Malta and Lampedusa are dominated by African motion.

Synchronized Position and Hold Reorient Experimental Satellites - International Space Station (SPHERES-ISS), Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Payload Systems Inc. (PSI) and the MIT Space Systems Laboratory (MIT-SSL) propose an innovative research program entitled SPHERES-ISS that uses their satellite...

Using GPS and leveling data in local precise geoid determination and case study

Science.gov (United States)

Erol, B.; Çelik, R. N.; Erol, S.

2003-04-01

As an important result of developments in high technology, satellite based positioning system has become to use in geodesy and surveying professions. These developments made the measurement works more accurate, more practical and more economic. Today, one of the most recent used satellite based positioning system is GPS (Global Positioning System) and it serves to a very wide range of geodetic applications from monitoring earth crustal deformations till building the basis for a GIS (Geographical Information Systems). The most efficient way to utilize GPS measurement system for mentioned aims is having a reliable geodetic infrastructure in working area. Geodetic infrastructure is a extraterrestrial and time system and involved 4D geodetic reference networks. The forth element of mentioned geodetic reference system is time because having an accurate and reliable geodetic infrastructure is needed to up-date according to physical realities of the region. By the help of a well designed geodetic infrastructure accurate and reliable coordinates of a point can be generated economically every time in a global and up-to-date system. Geoid is one of the important parts of a geodetic infrastructure. As it is well known, geoid is the equipotential surface of the Earth's gravity field which best fits, in a least squares sense, global mean sea level and it is reference for physical height systems like orthometric and normal heights. In the most of the applications, vertical position of a point is expressed with orthometric or normal height. Orthometric or normal height is a physical concept and gives vertical position of a point uniquely. On the other hand, vertical position of a point is derived in a geometrical system according to GPS measurements. GPS datum is WGS84 and in this system, an ellipsoidal height of a point is calculated according to WGS84 ellipsoid. So, it is an necessity to transform the ellipsoidal heights to orthometric heights and this procedure is managed with

Smart Device-Supported BDS/GNSS Real-Time Kinematic Positioning for Sub-Meter-Level Accuracy in Urban Location-Based Services

Directory of Open Access Journals (Sweden)

Liang Wang

2016-12-01

Full Text Available Using mobile smart devices to provide urban location-based services (LBS with sub-meter-level accuracy (around 0.5 m is a major application field for future global navigation satellite system (GNSS development. Real-time kinematic (RTK positioning, which is a widely used GNSS-based positioning approach, can improve the accuracy from about 10–20 m (achieved by the standard positioning services to about 3–5 cm based on the geodetic receivers. In using the smart devices to achieve positioning with sub-meter-level accuracy, a feasible solution of combining the low-cost GNSS module and the smart device is proposed in this work and a user-side GNSS RTK positioning software was developed from scratch based on the Android platform. Its real-time positioning performance was validated by BeiDou Navigation Satellite System/Global Positioning System (BDS/GPS combined RTK positioning under the conditions of a static and kinematic (the velocity of the rover was 50–80 km/h mode in a real urban environment with a SAMSUNG Galaxy A7 smartphone. The results show that the fixed-rates of ambiguity resolution (the proportion of epochs of ambiguities fixed for BDS/GPS combined RTK in the static and kinematic tests were about 97% and 90%, respectively, and the average positioning accuracies (RMS were better than 0.15 m (horizontal and 0.25 m (vertical for the static test, and 0.30 m (horizontal and 0.45 m (vertical for the kinematic test.

GLAS/ICESat L2 Sea Ice Altimetry Data (HDF5) V034

Data.gov (United States)

National Aeronautics and Space Administration — GLAH13 contains sea ice and open ocean elevations corrected for geodetic and atmospheric affects, calculated from algorithms fine-tuned for sea ice returns. Granules...

GLAS/ICESat L2 Sea Ice Altimetry Data V033

Data.gov (United States)

National Aeronautics and Space Administration — GLA13 contains sea ice and open ocean elevations corrected for geodetic and atmospheric affects, calculated from algorithms fine-tuned for sea ice returns. Granules...

Yoga Communities and Eating Disorders: Creating Safe Space for Positive Embodiment.

Science.gov (United States)

Cook-Cottone, Catherine; Douglass, Laura Lee

2017-11-01

With adequate education and guidance, yoga communities, as part of the therapeutic landscape in the 21st century, can play a significant role promoting positive embodiment for those with, and at-risk for, eating disorders (EDs). To do this, yoga teachers need to know how to create a body-positive community and be able to recognize and respond to those at risk and struggling with EDs in their communities. In order to address yoga teaching methods associated with EDs and ED risk, broader conceptual approaches and specific practices associated with positive embodiment are offered. These include the broader conceptual approaches of: intentional inclusion and acceptance, experiential emphasis, supporting positive embodiment and inquiry. Studio pragmatics are also detailed as related to the body, breath, emotions, and community. Assessment, referral, and community engagement are also addressed.

Forecasting Space Weather-Induced GPS Performance Degradation Using Random Forest

Science.gov (United States)

Filjar, R.; Filic, M.; Milinkovic, F.

2017-12-01

Space weather and ionospheric dynamics have a profound effect on positioning performance of the Global Satellite Navigation System (GNSS). However, the quantification of that effect is still the subject of scientific activities around the world. In the latest contribution to the understanding of the space weather and ionospheric effects on satellite-based positioning performance, we conducted a study of several candidates for forecasting method for space weather-induced GPS positioning performance deterioration. First, a 5-days set of experimentally collected data was established, encompassing the space weather and ionospheric activity indices (including: the readings of the Sudden Ionospheric Disturbance (SID) monitors, components of geomagnetic field strength, global Kp index, Dst index, GPS-derived Total Electron Content (TEC) samples, standard deviation of TEC samples, and sunspot number) and observations of GPS positioning error components (northing, easting, and height positioning error) derived from the Adriatic Sea IGS reference stations' RINEX raw pseudorange files in quiet space weather periods. This data set was split into the training and test sub-sets. Then, a selected set of supervised machine learning methods based on Random Forest was applied to the experimentally collected data set in order to establish the appropriate regional (the Adriatic Sea) forecasting models for space weather-induced GPS positioning performance deterioration. The forecasting models were developed in the R/rattle statistical programming environment. The forecasting quality of the regional forecasting models developed was assessed, and the conclusions drawn on the advantages and shortcomings of the regional forecasting models for space weather-caused GNSS positioning performance deterioration.

A System to Produce Precise Global GPS Network Solutions for all Geodetic GPS Stations in the World

Science.gov (United States)

Blewitt, G.; Kreemer, C. W.

2010-12-01

We have developed an end-to-end system that automatically seeks and routinely retrieves geodetic GPS data from ~5000 stations (currently) around the globe, reduces the data into unique, daily global network solutions, and produces high precision time series for station coordinates ready for time-series analysis, geophysical modeling and interpretation. Moreover, “carrier range” data are produced for all stations, enabling epoch-by-epoch tracking of individual station motions by precise point positioning for investigation of sub-daily processes, such as post-seismic after-slip and ocean tidal loading. Solutions are computed in a global reference frame aligned to ITRF, and optionally in user-specified continental-scale reference frames that can filter out common-mode signals to enhance regional strain anomalies. We describe the elements of this system, the underlying signal processing theory, the products, operational statistics, and scientific applications of our system. The system is fundamentally based on precise point positioning using JPL's GIPSY OASIS II software, coupled with ambiguity resolution and a global network adjustment of ~300,000 parameters per day using our newly developed Ambizap3 software. The system is designed to easily and efficiently absorb stations that deliver data very late, by recycling prior computations in the network adjustment, such that the resulting network solution is identical to starting from scratch. Thus, it becomes possible to trawl continuously the Internet for late arriving data, or for newly discovered data, and seamlessly update all GPS station time series using the new information content. As new stations are added to the processing archive, automated e-mail requests are made to H.-G. Scherneck's server at Chalmers University to compute ocean loading coefficients used by the station motion model. Rinex file headers are parsed and compared with alias tables in order to infer the correct receiver type and antenna

The International GPS Service (IGS) as a Continuous Reference System for Precise GPS Positioning

Science.gov (United States)

Neilan, Ruth; Heflin, Michael; Watkins, Michael; Zumberge, James

1996-01-01

The International GPS Service for Geodynamics (IGS) is an organization which operates under the auspices of the International Association of Geodesy (IAG) and has been operational since January 1994. The primary objective of the IGS is to provide precise GPS data and data products to support geodetic and geophysical research activities.

Self-calibrating solar position sensor

Science.gov (United States)

Maxey, Lonnie Curt

2018-01-30

A sun positioning sensor and method of accurately tracking the sun are disclosed. The sensor includes a position sensing diode and a disk having a body defining an aperture for accepting solar light. An extension tube having a body that defines a duct spaces the position sensing diode from the disk such that the solar light enters the aperture in the disk, travels through the duct in the extension tube and strikes the position sensing diode. The extension tube has a known length that is fixed. Voltage signals indicative of the location and intensity of the sun are generated by the position sensing diode. If it is determined that the intensity values are unreliable, then historical position values are used from a table. If the intensity values are deemed reliable, then actual position values are used from the position sensing diode.

Web-site of the UGKK. The core of national spatial infrastructure

International Nuclear Information System (INIS)

Lacena, M.; Klobusiak, M.

2005-01-01

Geodetic and Cartographic Institute Bratislava (GKU) as an executive organization of government department Geodesy, Cartography and Cadastre Authority of the Slovak Republic (Urad geodezie, kartografie a katastra na Slovensku UGKK SR) is a provider and administrator of geodetic fundamentals and basic database of reference data of GIS. It creates one of most important elements of space data infrastructure of the Slovak Republic. The Open Source software UMN MapServer was selected for creating of web-application. The web site of the UGKK SR, its structure, services and perspective are discussed

Quantifying the short- and long-term controls exerted by the basal and lateral boundaries of the Slumgullion Landslide from creepmeters and 3-D surface deformation

Science.gov (United States)

Delbridge, B. G.; Bilham, R. G.; Wang, T.; Fielding, E. J.; Burgmann, R.

2017-12-01

The Slumgullion landslide is 3.9 km long, moves persistently with peak rates of up to 2 cm/day, and exhibits daily, seasonal, and decadal accelerations. In this study, we provide geodetic observations needed to test whether the short- and long-term variations are governed by the same physical mechanisms. Specific focus is placed on disentangling the roles played by the lateral and basal landslide surfaces. In order to provide surface geodetic measurements with dense spatial resolution (pixel spacing Hall effect sensor, resulting in resolution of 8 microns and with a 5 m range.

Monitoring of Volcanic Activity by Sub-mm Geodetic Analyses

Science.gov (United States)

Miura, S.; Mare, Y.; Ichiki, M.; Demachi, T.; Tachibana, K.; Nishimura, T.

2017-12-01

Volcanic earthquakes have been occurring beneath Zao volcano in northern Honshu, Japan since 2013, following the increase of deep low frequency earthquakes from 2012. On account of a burst of seismicity initiated in April 2015, the JMA announced a warning of eruption, however, the seismicity gradually decreased for the next two months and the warning was canceled in June. In the same time period, minor expansive deformation was observed by GNSS. Small earthquakes are still occurring, and low-freq. earthquakes (LPE) occur sometimes accompanied by static tilt changes. In this study, we try to extract the sub-mm displacements from the LPE waveforms observed by broadband seismometers (BBS) and utilize them for geodetic inversion to monitor volcanic activities. Thun et al. (2015, 2016) devised an efficient method using a running median filter (RMF) to remove LP noises, which contaminate displacement waveforms. They demonstrated the reproducibility of the waveforms corresponding to the experimentally given sub-mm displacements in the laboratory. They also apply the method to the field LPE data obtained from several volcanoes to show static displacements. The procedure is outlined as follows: (1) Unfiltered removal of the instrument response, (2) LP noise estimate by LPF with a corner frequency of 5/M, where M (seconds) is the time window of the RMF and should be at least three times the length of the rise time. (3) Subtract the noise estimated from step (2). (4) Integrate to obtain displacement waveforms. We apply the method to the BBS waveform at a distance of about 1.5 km ESE from the summit crater of Zao Volcano associated with a LPE on April 1, 2017. Assuming the time window M as 300 seconds, we successfully obtained the displacement history: taking the rise time of about 2 minutes, the site was gradually uplifted with the amount of about 50-60 µm and then subsided with HF displacements in the next 2 minutes resulting about 20-30 µm static upheaval. Comparing the

Time biases in laser ranging observations: A concerning issue of Space Geodesy

Science.gov (United States)

Exertier, Pierre; Belli, A.; Lemoine, J. M.

2017-09-01

Time transfer by Laser Ranging (LR) recently demonstrated a remarkable stability (a few ps over ∼1000 s) and accuracy (synchronizing both space and ground clocks over distances from a few thousands to tens of thousands kilometers. Given its potential role in navigation, fundamental physics and metrology, it is crucial that synergy between laser ranging and Time&Frequency (T/F) technologies improves to meet the present and future space geodesy requirements. In this article, we examine the behavior of T/F systems that are used in LR tracking stations of the international laser ranging service. The approach we investigate is to compute time synchronization between clocks used at LR stations using accurate data of the Time Transfer by Laser Link (T2L2) experiment onboard the satellite Jason-2 (Samain et al., 2014). Systematic time biases are estimated against the UTC time scale for a set of 22 observing stations in 2013, in the range of zero to a few μ s. Our results suggest that the ILRS network suffers from accuracy issues, due to time biases in the laser ranging observations. We discuss how these systematic effects impact the precise orbit determination of LAGEOS geodetic satellites over a 1-year analysis, and additionally give a measure of the local effect into station coordinates, regarding in particular the effect in the east-west component that is of 2-6 mm for a typical systematic time bias of one μ s.

Solitons in dusty plasmas with positive dust grains

International Nuclear Information System (INIS)

Baluku, T. K.; Hellberg, M. A.; Mace, R. L.

2008-01-01

Although ''typical'' micrometer-sized dust grains in a space or laboratory plasma are often negatively charged because of collisions with the mobile electrons, there are environments in which grains may take on a positive charge. We consider a dusty plasma composed of electrons, positive ions and positive dust grains, and use the fluid dynamic paradigm to identify existence domains in parameter space for both dust-acoustic (DA) and dust-modified ion-acoustic (DIA) solitons. Only positive potential DA solitons are found. This represents an expected antisymmetry with the case of negative dust, where previously only negative solitons were reported. However, whereas for negative dust DIA solitons of either sign of potential may exist, we find that for the case of positive dust, DIA solitons are restricted to positive potentials only. The results for both positive and negative dust are consistent with an hypothesis that, in the absence of flows, the sign(s) of the soliton potential coincide(s) with the sign(s) of the species whose inertia is included in the calculation; i.e., the cold, supersonic species present in the plasma

Open Problem: Kernel methods on manifolds and metric spaces

DEFF Research Database (Denmark)

Feragen, Aasa; Hauberg, Søren

2016-01-01

Radial kernels are well-suited for machine learning over general geodesic metric spaces, where pairwise distances are often the only computable quantity available. We have recently shown that geodesic exponential kernels are only positive definite for all bandwidths when the input space has strong...... linear properties. This negative result hints that radial kernel are perhaps not suitable over geodesic metric spaces after all. Here, however, we present evidence that large intervals of bandwidths exist where geodesic exponential kernels have high probability of being positive definite over finite...... datasets, while still having significant predictive power. From this we formulate conjectures on the probability of a positive definite kernel matrix for a finite random sample, depending on the geometry of the data space and the spread of the sample....

Rethinking humanitarian space

OpenAIRE

Ahmad, Sana

2016-01-01

This study looks at the humanitarian space in Myanmar which includes not just the humanitarian operations in the country, the access to volatile zones by the humanitarian organisations, the humanitarian principles, but also a space which permits a complementary arrangement of diverse actors holding different positions and skill sets and deliver to those in need. The study is based on the practical experiences and reflections of these different actors on field and their operations in different...

Positive projections of symmetric matrices and Jordan algebras

DEFF Research Database (Denmark)

Fuglede, Bent; Jensen, Søren Tolver

2013-01-01

An elementary proof is given that the projection from the space of all symmetric p×p matrices onto a linear subspace is positive if and only if the subspace is a Jordan algebra. This solves a problem in a statistical model.......An elementary proof is given that the projection from the space of all symmetric p×p matrices onto a linear subspace is positive if and only if the subspace is a Jordan algebra. This solves a problem in a statistical model....

String cohomology groups of complex projective spaces

DEFF Research Database (Denmark)

Ottosen, Iver; Bökstedt, Marcel

2007-01-01

Let X be a space and write LX for its free loop space equipped with the action of the circle group T given by dilation. The equivariant cohomology H*(LXhT;Z/p) is a module over H*(BT;Z/p). We give a computation of this module when X=CPr for any positive integer r and any prime number p. The compu......Let X be a space and write LX for its free loop space equipped with the action of the circle group T given by dilation. The equivariant cohomology H*(LXhT;Z/p) is a module over H*(BT;Z/p). We give a computation of this module when X=CPr for any positive integer r and any prime number p...

Monitoring deep geodynamic processes within Vrancea intermediate-depth seismic zone by geodetic means

Science.gov (United States)

Besutiu, Lucian; Zlagnean, Luminita

2015-04-01

Background Located in the bending zone of East Carpathians, the so-called Vrancea zone is one of the most active seismic regions in Europe. Despite many years of international research, its intermediate-depth seismicity within full intra-continental environment still represents a challenge of the 21st century. Infrastructure In the attempt to join the above-mentioned efforts, the Solid Earth Dynamics Department (SEDD) in the Institute of Geodynamics of the Romanian Academy has developed a special research infrastructure, mainly devoted to gravity and space geodesy observations. A geodetic network covering the epicentre area of the intermediate-depth earthquakes has been designed and implemented for monitoring deep geodynamic processes and their surface echoes. Within each base-station of the above-mentioned network, a still-reinforced concrete pillar allows for high accuracy repeated gravity and GPS determinations. Results Starting from some results of the previously run CERGOP and UNIGRACE European programmes, to which additional SEDD repeated field campaigns were added, an unusual geodynamic behaviour has been revealed in the area. 1) Crust deformation: unlike the overall uprising of East Carpathians, as a result of denudation followed by erosion, their SE bending zone, with Vrancea epicentre area exhibits a slight subsidence. 2) Gravity change: more than 200 microgals non-tidal gravity decrease over a 20 years time-span has been noticed within the subsiding area. Extended observations showed the gravity lowering as a nowadays continuing process. Interpretation This strange combination of topography subsidence and gravity lowering has been interpreted in terms of crust stretching in the Vrancea epicentre zone due to the gravity pull created by densification of the lower crust as a result of phase-transform processes taking place in the lithospheric compartment sunken into the upper mantle. The occurrence of crust earthquakes with vertical-extension focal

Integrating Geological and Geodetic Surveying Techniques for Landslide Deformation Monitoring: Istanbul Case

Science.gov (United States)

Menteşe, E. Y.; Kilic, O.; BAS, M.; Tarih, A.; Duran, K.; Gumus, S.; Yapar, E. R.; Karasu, M. E.; Mehmetoğlu, H.; Karaman, A.; Edi˙ger, V.; Kosma, R. C.; Ozalaybey, S.; Zor, E.; Arpat, E.; Polat, F.; Dogan, U.; Cakir, Z.; Erkan, B.

2017-12-01

There are several methods that can be utilized for describing the landslide mechanisms. While some of them are commonly used, there are relatively new methods that have been proven to be useful. Obviously, each method has its own limitations and thus integrated use of these methods contributes to obtaining a realistic landslide model. The slopes of Küçükçekmece and Büyükçekmece Lagoons located at the Marmara Sea coast of İstanbul, Turkey, are among most specific examples of complex type landslides. The landslides in the area started developing at low sea level, and appears to ceased or at least slowed down to be at minimum after the sea level rise, as oppose to the still-active landslides that continue to cause damage especially in the valley slopes above the recent sea level between the two lagoons. To clarify the characteristics of these slope movements and classify them in most accurate way, Directorate of Earthquake and Ground Research of Istanbul Metropolitan Municipality launched a project in cooperation with Marmara Research Center of The Scientific and Technological Research Council of Turkey (TÜBİTAK). The project benefits the utility of the techniques of different disciplines such as geology, geophysics, geomorphology, hydrogeology, geotechnics, geodesy, remote sensing and meteorology. Specifically, this study focuses on two main axes of these techniques, namely: geological and geodetic. The reason for selecting these disciplines is because of their efficiency and power to understand the landslide mechanism in the area. Main approaches used in these studies are comprised of geological drills, inclinometer measurements, GPS surveys and SAR (both satellite and ground based) techniques. Integration of the results gathered from these techniques led the project team to comprehend critical aspects of landslide phenomenon in the area and produce precise landslide hazard maps that are basic instruments for a resilient urban development.

Geodetic data support trapping of ethane in Titan's polar crust

Science.gov (United States)

Sotin, Christophe; Rambaux, Nicolas

2016-04-01

Titan's surface is characterized by polar depressions that strongly influence interpretations of the gravity data. This study investigates several geodynamical models that can explain these depressions. For each model, the values of the three moments of inertia are computed numerically by discretizing the interior in spherical coordinates. The study shows that a Pratt model where the polar subsurface is made of ethane clathrates can explain the polar depression, the abrupt jump in altitude at about 60 degrees latitude, and the values of the degree 2 gravity coefficients. This model, proposed by Choukroun and Sotin [1], is based on the stability of ethane clathrate hydrates relative to methane clathrate hydrates. In addition to fitting the geodetic data, it explains the absence of ethane in Titan's atmosphere although ethane is the main product of the photolysis of methane. Other geophysical models based on latitudinal variations in the tidal heating production or in the heat flux at the base of the icy crust do not provide such a good match to the gravity and topographic observations. The ethane-clathrate model predicts that all the ethane produced by photolysis of methane at the present rate during the last billion years could be stored in the polar subsurface. It is consistent with the age of Titan's surface and that of Titan's atmospheric methane inferred from geological and geochemical observations by the Cassini/Huygens mission. The present study also emphasizes the role of mass anomalies on the interpretation of the degree 2 gravity coefficients. It shows that for Titan, a slow rotator, the values of the two equatorial moments of inertia (MoI) are largely affected by the polar depressions whereas the value of polar MoI is not. Therefore, as pointed out by previous calculations [2], calculating the moment of inertia (MoI) factor from the value of J2 could lead to major errors. This is not the case for our preferred Titan's model for which the negative polar

Strings from position-dependent noncommutativity

International Nuclear Information System (INIS)

Fring, Andreas; Gouba, Laure; Scholtz, Frederik G

2010-01-01

We introduce a new set of noncommutative spacetime commutation relations in two space dimensions. The space-space commutation relations are deformations of the standard flat noncommutative spacetime relations taken here to have position-dependent structure constants. Some of the new variables are non-Hermitian in the most natural choice. We construct their Hermitian counterparts by means of a Dyson map, which also serves to introduce a new metric operator. We propose PT-like symmetries, i.e. antilinear involutory maps, respected by these deformations. We compute minimal lengths and momenta arising in this space from generalized versions of Heisenberg's uncertainty relations and find that any object in this two-dimensional space is string like, i.e. having a fundamental length in one direction beyond which a resolution is impossible. Subsequently, we formulate and partly solve some simple models in these new variables, the free particle, its PT-symmetric deformations and the harmonic oscillator.

Geodetic Networks, This is udated by the use of GPS and updated weekely. It consist of interstate highways, state highways, major roads and local roads as well as private streets with address range, speed limit and elevation data associated to each segement., Published in 2007, Johnson County Government.

Data.gov (United States)

NSGIC Local Govt | GIS Inventory — Geodetic Networks dataset current as of 2007. This is udated by the use of GPS and updated weekely. It consist of interstate highways, state highways, major roads...

BIOGAS PLANT AS AN ELEMENT THAT HAS A POSITIVE INFLUENCE ON THE ENVIRONMENTAL CHANGES OF RURAL SPACE

Directory of Open Access Journals (Sweden)

Wojciech Pawłowski

2017-10-01

Full Text Available In the contemporary rural landscape, an agricultural biogas plant is becoming an increasingly frequent element of agricultural installations. There is a need to ask an important question: is a new technology, such as biogas plants with medium power of 1MW, listed as investments which can have significant environmental impacts? This question is becoming an integral part of rural space as a new form of village buildings. The inevitable changes in the rural landscape and the way of carrying out farming have both a positive and negative impact on the rural environment. Biogas plants, as new objects in developing country industries, are undoubtedly an important element in the way of obtaining green energy. Location is the most important factor for the success of the establishment and operation of the biogas plant, which is important not only for economic reasons, but also socio-environmental and landscape reasons.

On Uniformly finitely extensible Banach spaces

OpenAIRE

Castillo, Jesús M. F.; Ferenczi, Valentin; Moreno, Yolanda

2013-01-01

We continue the study of Uniformly Finitely Extensible Banach spaces (in short, UFO) initiated in Moreno-Plichko, \\emph{On automorphic Banach spaces}, Israel J. Math. 169 (2009) 29--45 and Castillo-Plichko, \\emph{Banach spaces in various positions.} J. Funct. Anal. 259 (2010) 2098-2138. We show that they have the Uniform Approximation Property of Pe\\l czy\\'nski and Rosenthal and are compactly extensible. We will also consider their connection with the automorphic space problem of Lindenstraus...

On the use of one-dimensional position sensitive detector for x-ray diffraction reciprocal space mapping: Data quality and limitations

International Nuclear Information System (INIS)

Masson, Olivier; Boulle, Alexandre; Guinebretiere, Rene; Lecomte, Andre; Dauger, Alain

2005-01-01

A homemade x-ray diffractometer using one-dimensional position sensitive detector (PSD) and well suited to the study of thin epitaxial layer systems is presented. It is shown how PSDs can be advantageously used to allow fast reciprocal space mapping, which is especially interesting when analyzing poor crystalline and defective layers as usually observed with oxides and ceramics films. The quality of the data collected with such a setup and the limitations of PSDs in comparison with the use of analyzer crystals are discussed. In particular, the effects of PSD on angular precision, instrument resolution and corrections that must be applied to raw data are presented

Using DORIS measurements for ionosphere modeling

Science.gov (United States)

Dettmering, Denise; Schmidt, Michael; Limberger, Marco

2013-04-01

Nowadays, most of the ionosphere models used in geodesy are based on terrestrial GNSS measurements and describe the Vertical Total Electron Content (VTEC) depending on longitude, latitude, and time. Since modeling the height distribution of the electrons is difficult due to the measurement geometry, the VTEC maps are based on the the assumption of a single-layer ionosphere. Moreover, the accuracy of the VTEC maps is different for different regions of the Earth, because the GNSS stations are unevenly distributed over the globe and some regions (especially the ocean areas) are not very well covered by observations. To overcome the unsatisfying measurement geometry of the terrestrial GNSS measurements and to take advantage of the different sensitivities of other space-geodetic observation techniques, we work on the development of multi-dimensional models of the ionosphere from the combination of modern space-geodetic satellite techniques. Our approach consists of a given background model and an unknown correction part expanded in terms of B-spline functions. Different space-geodetic measurements are used to estimate the unknown model coefficients. In order to take into account the different accuracy levels of the observations, a Variance Component Estimation (VCE) is applied. We already have proven the usefulness of radio occultation data from space-borne GPS receivers and of two-frequency altimetry data. Currently, we test the capability of DORIS observations to derive ionospheric parameters such as VTEC. Although DORIS was primarily designed for precise orbit computation of satellites, it can be used as a tool to study the Earth's ionosphere. The DORIS ground beacons are almost globally distributed and the system is on board of various Low Earth Orbiters (LEO) with different orbit heights, such as Jason-2, Cryosat-2, and HY-2. The last generation of DORIS receivers directly provides phase measurements on two frequencies. In this contribution, we test the DORIS

Sciences of geodesy II innovations and future developments

CERN Document Server

Xu, Guochang

2014-01-01

This series of reference books describes the sciences of different fields in and around geodesy. Each chapter, is written by experts in the respective fields and covers an individual field and describes the history, theory, the objective, the technology, and the development, the highlight of the research, the applications, the problems, as well as future directions. Contents of Volume II include: Geodetic LEO Satellite Missions, Satellite Altimetry, Airborne Lidar, GNSS Software Receiver, Geodetic Boundary Problem, GPS and INS, VLBI, Geodetic Reference Systems, Spectral Analysis, Earth Tide and Ocean Loading Tide, Remote Sensing, Photogrammetry, Occultation, Geopotential Determination, Geoid Determination, Local Gravity Field, Geopotential Determination, Magnet Field, Mobile Mapping, General Relativity, Wide-area Precise Positioning etc.

Global height datum unification: a new approach in gravity potential space

Science.gov (United States)

Ardalan, A. A.; Safari, A.

2005-12-01

The problem of “global height datum unification” is solved in the gravity potential space based on: (1) high-resolution local gravity field modeling, (2) geocentric coordinates of the reference benchmark, and (3) a known value of the geoid’s potential. The high-resolution local gravity field model is derived based on a solution of the fixed-free two-boundary-value problem of the Earth’s gravity field using (a) potential difference values (from precise leveling), (b) modulus of the gravity vector (from gravimetry), (c) astronomical longitude and latitude (from geodetic astronomy and/or combination of (GNSS) Global Navigation Satellite System observations with total station measurements), (d) and satellite altimetry. Knowing the height of the reference benchmark in the national height system and its geocentric GNSS coordinates, and using the derived high-resolution local gravity field model, the gravity potential value of the zero point of the height system is computed. The difference between the derived gravity potential value of the zero point of the height system and the geoid’s potential value is computed. This potential difference gives the offset of the zero point of the height system from geoid in the “potential space”, which is transferred into “geometry space” using the transformation formula derived in this paper. The method was applied to the computation of the offset of the zero point of the Iranian height datum from the geoid’s potential value W 0=62636855.8 m2/s2. According to the geometry space computations, the height datum of Iran is 0.09 m below the geoid.

Optimal Detection Range of RFID Tag for RFID-based Positioning System Using the k-NN Algorithm

Directory of Open Access Journals (Sweden)

Joon Heo

2009-06-01

Full Text Available Positioning technology to track a moving object is an important and essential component of ubiquitous computing environments and applications. An RFID-based positioning system using the k-nearest neighbor (k-NN algorithm can determine the position of a moving reader from observed reference data. In this study, the optimal detection range of an RFID-based positioning system was determined on the principle that tag spacing can be derived from the detection range. It was assumed that reference tags without signal strength information are regularly distributed in 1-, 2- and 3-dimensional spaces. The optimal detection range was determined, through analytical and numerical approaches, to be 125% of the tag-spacing distance in 1-dimensional space. Through numerical approaches, the range was 134% in 2-dimensional space, 143% in 3-dimensional space.

Thermal expansion of an amorphous alloy. Reciprocal-space versus real-space distribution functions

International Nuclear Information System (INIS)

Louzguine-Luzgin, Dmitri V.; Inoue, Akihisa

2007-01-01

This paper describes the relation between the change in the position of the first X-ray diffraction maximum in reciprocal space and the first maximum of the distribution function in real space for the Ge 50 Al 40 Cr 10 amorphous alloy. It is also shown that the first diffraction maximum of the interference function carries the most significant information about the interatomic distances in real space while the subsequent peaks of the interference function are responsible for the shoulders of the main peak of the real-space distribution function. The results are used to support validity of the method previously used to monitor thermal expansion of the glassy alloys using an X-ray diffraction profile

Bundles over Quantum RealWeighted Projective Spaces

Directory of Open Access Journals (Sweden)

Tomasz Brzeziński

2012-09-01

Full Text Available The algebraic approach to bundles in non-commutative geometry and the definition of quantum real weighted projective spaces are reviewed. Principal U(1-bundles over quantum real weighted projective spaces are constructed. As the spaces in question fall into two separate classes, the negative or odd class that generalises quantum real projective planes and the positive or even class that generalises the quantum disc, so do the constructed principal bundles. In the negative case the principal bundle is proven to be non-trivial and associated projective modules are described. In the positive case the principal bundles turn out to be trivial, and so all the associated modules are free. It is also shown that the circle (coactions on the quantum Seifert manifold that define quantum real weighted projective spaces are almost free.

Space dosimetry measurement results using the Pille instrument during the EUROMIR/NASAMIR space flights

International Nuclear Information System (INIS)

Hejja, I.; Apathy, J.; Deme, S.

1997-01-01

The Pille dosimeter developed in Hungary for space applications is described briefly, and its two versions are presented for the two space flights. The results of the EUROMIR mission in 1995-1996 are discussed for positional dosimetric applications. The characteristic dose rates at various space stations in the Salyut range are displayed. The NASAMIR4 mission between January 1997 and September 1998 are also discussed from the dosimetric point of view. The results of the measurements are presented and a preliminary analysis is reported. (R.P.)

EPOS-IP WP10: services and data provision for the GNSS community

Science.gov (United States)

Fernandes, Rui

2016-04-01

The EPOS-IP WP10 - "GNSS Data & Products" is the Working Package of the EPOS-IP project in charge of implementing the necessary services in order that the geo-sciences community can access the existing Pan-European Geodetic Infrastructures. The WP10 is formed by representatives of the participating institutions (10) but it is also open to the entire geodetic community. In fact, WP10 also includes members from other institutions/countries that formally are not participating in the EPOS-IP. During the EPOS-IP project, the geodetic component of EPOS (WP10) is dealing essentially with Research Infrastructures focused on continuous operating GNSS (cGNSS). The option of concentrating the efforts on the presently most generalized geodetic tool supporting research on Solid Earth was decided in order to optimize the existing resources. Furthermore, although the focus is on Solid Earth applications, other research and technical applications (e.g., reference frames, meteorology, space weather) can also benefit from the efforts of WP10 towards the optimization of the geodetic resources in Europe. We will present and discuss the plans for the implementation of the thematic and core services (TCS) for GNSS data within EPOS and the related business plan. We will focus on strategies towards the implementation of the best solutions that will permit to the end-users, and in particular geo-scientists, to access the geodetic data, derived solutions, and associated metadata using transparent and uniform processes. The collaboration with EUREF is also an essential component of the implementation plan.

Estimation of position and velocity for a low dynamic vehicle in near space using nonresolved photometric and astrometric data.

Science.gov (United States)

Jing, Nan; Li, Chuang; Chong, Yaqin

2017-01-20

An estimation method for indirectly observable parameters for a typical low dynamic vehicle (LDV) is presented. The estimation method utilizes apparent magnitude, azimuth angle, and elevation angle to estimate the position and velocity of a typical LDV, such as a high altitude balloon (HAB). In order to validate the accuracy of the estimated parameters gained from an unscented Kalman filter, two sets of experiments are carried out to obtain the nonresolved photometric and astrometric data. In the experiments, a HAB launch is planned; models of the HAB dynamics and kinematics and observation models are built to use as time update and measurement update functions, respectively. When the HAB is launched, a ground-based optoelectronic detector is used to capture the object images, which are processed using aperture photometry technology to obtain the time-varying apparent magnitude of the HAB. Two sets of actual and estimated parameters are given to clearly indicate the parameter differences. Two sets of errors between the actual and estimated parameters are also given to show how the estimated position and velocity differ with respect to the observation time. The similar distribution curve results from the two scenarios, which agree within 3σ, verify that nonresolved photometric and astrometric data can be used to estimate the indirectly observable state parameters (position and velocity) for a typical LDV. This technique can be applied to small and dim space objects in the future.

Generalized space-charge limited current and virtual cathode behaviors in one-dimensional drift space

International Nuclear Information System (INIS)

Yang, Zhanfeng; Liu, Guozhi; Shao, Hao; Chen, Changhua; Sun, Jun

2013-01-01

This paper reports the space-charge limited current (SLC) and virtual cathode behaviors in one-dimensional grounded drift space. A simple general analytical solution and an approximate solution for the planar diode are given. Through a semi-analytical method, a general solution for SLC in one-dimensional drift space is obtained. The behaviors of virtual cathode in the drift space, including dominant frequency, electron transit time, position, and transmitted current, are yielded analytically. The relationship between the frequency of the virtual cathode oscillation and the injected current presented may explain previously reported numerical works. Results are significant in facilitating estimations and further analytical studies

Analysis of web-based online services for GPS relative and precise point positioning techniques

Directory of Open Access Journals (Sweden)

Taylan Ocalan

Full Text Available Nowadays, Global Positioning System (GPS has been used effectively in several engineering applications for the survey purposes by multiple disciplines. Web-based online services developed by several organizations; which are user friendly, unlimited and most of them are free; have become a significant alternative against the high-cost scientific and commercial software on achievement of post processing and analyzing the GPS data. When centimeter (cm or decimeter (dm level accuracies are desired, that can be obtained easily regarding different quality engineering applications through these services. In this paper, a test study was conducted at ISKI-CORS network; Istanbul-Turkey in order to figure out the accuracy analysis of the most used web based online services around the world (namely OPUS, AUSPOS, SCOUT, CSRS-PPP, GAPS, APPS, magicGNSS. These services use relative and precise point positioning (PPP solution approaches. In this test study, the coordinates of eight stations were estimated by using of both online services and Bernese 5.0 scientific GPS processing software from 24-hour GPS data set and then the coordinate differences between the online services and Bernese processing software were computed. From the evaluations, it was seen that the results for each individual differences were less than 10 mm regarding relative online service, and less than 20 mm regarding precise point positioning service. The accuracy analysis was gathered from these coordinate differences and standard deviations of the obtained coordinates from different techniques and then online services were compared to each other. The results show that the position accuracies obtained by associated online services provide high accurate solutions that may be used in many engineering applications and geodetic analysis.

Locating and defining underground goaf caused by coal mining from space-borne SAR interferometry

Science.gov (United States)

Yang, Zefa; Li, Zhiwei; Zhu, Jianjun; Yi, Huiwei; Feng, Guangcai; Hu, Jun; Wu, Lixin; Preusse, Alex; Wang, Yunjia; Papst, Markus

2018-01-01

It is crucial to locate underground goafs (i.e., mined-out areas) resulting from coal mining and define their spatial dimensions for effectively controlling the induced damages and geohazards. Traditional geophysical techniques for locating and defining underground goafs, however, are ground-based, labour-consuming and costly. This paper presents a novel space-based method for locating and defining the underground goaf caused by coal extraction using Interferometric Synthetic Aperture Radar (InSAR) techniques. As the coal mining-induced goaf is often a cuboid-shaped void and eight critical geometric parameters (i.e., length, width, height, inclined angle, azimuth angle, mining depth, and two central geodetic coordinates) are capable of locating and defining this underground space, the proposed method reduces to determine the eight geometric parameters from InSAR observations. Therefore, it first applies the Probability Integral Method (PIM), a widely used model for mining-induced deformation prediction, to construct a functional relationship between the eight geometric parameters and the InSAR-derived surface deformation. Next, the method estimates these geometric parameters from the InSAR-derived deformation observations using a hybrid simulated annealing and genetic algorithm. Finally, the proposed method was tested with both simulated and two real data sets. The results demonstrate that the estimated geometric parameters of the goafs are accurate and compatible overall, with averaged relative errors of approximately 2.1% and 8.1% being observed for the simulated and the real data experiments, respectively. Owing to the advantages of the InSAR observations, the proposed method provides a non-contact, convenient and practical method for economically locating and defining underground goafs in a large spatial area from space.

Asympotics with positive cosmological constant

Science.gov (United States)

Bonga, Beatrice; Ashtekar, Abhay; Kesavan, Aruna

2014-03-01

Since observations to date imply that our universe has a positive cosmological constant, one needs an extension of the theory of isolated systems and gravitational radiation in full general relativity from the asymptotically flat to asymptotically de Sitter space-times. In current definitions, one mimics the boundary conditions used in asymptotically AdS context to conclude that the asymptotic symmetry group is the de Sitter group. However, these conditions severely restricts radiation and in fact rules out non-zero flux of energy, momentum and angular momentum carried by gravitational waves. Therefore, these formulations of asymptotically de Sitter space-times are uninteresting beyond non-radiative spacetimes. The situation is compared and contrasted with conserved charges and fluxes at null infinity in asymptotically flat space-times.

UNAVCO: A Decade Supporting EarthScope - Three Decades of Supporting Geodesy for Science Innovation

Science.gov (United States)

Miller, M.

2013-12-01

UNAVCO supports research that establishes Earth's reference frame, enabling mapping of the planet's shape and mass; determines changes in the distribution of ice, water resources, and sea level; characterizes processes that contribute to natural and man-made hazards; and recognizes land-use changes (including subsidence, soil moisture, and health of wetlands). UNAVCO began as an investigator cooperative in 1984 - with the goal of sharing equipment and technologies that were expensive, rapidly changing, and extraordinarily powerful. Today as NSF's National Earth Science Geodetic Facility, on the eve of our 30th anniversary, we are excited to highlight a decade of support for major components of EarthScope, especially the Plate Boundary Observatory (PBO). Innovations by UNAVCO and the UNAVCO community have supported steady advancement towards millimeter-level global geodesy. Modern space geodesy provides new observational capability for contemporary deformation and magmatism in active convergent margin systems that operate over a spectrum of temporal and spatial scales, especially the PBO. Time scales vary from seconds to millennia, and spatial scales from borehole nanostrains to the global plate circuit. High-precision strain or 3-D point observations with borehole strainmeter or Global Positioning System (GPS) observations and geodetic imaging with SAR and LiDAR are used in combination to reveal these complex systems. GPS now combines with strong ground motion accelerometer time series to provide important enhancements to conventional seismology. The resulting 3-D fully georeferenced dynamic positioning time series are free of ambiguities associated with seismometer tilt and displacement. Geodesy constrains plate kinematics for convergence rate and direction, co-seismic deformation during great and moderate earthquakes, episodic tremor and slip events and related transient deformation, tectono-magmatic interactions, and the possible triggering effects of

Analyticity spaces of self-adjoint operators subjected to perturbations with applications to Hankel invariant distribution spaces

NARCIS (Netherlands)

Eijndhoven, van S.J.L.; Graaf, de J.

1986-01-01

A new theory of generalized functions has been developed by one of the authors (de Graaf). In this theory the analyticity domain of each positive self-adjoint unbounded operator $\\mathcal{A}$ in a Hilbert space $X$ is regarded as a test space denoted by $\\mathcal{S}_{x,\\mathcal{A}} $. In the first

An advanced complex analysis problem book topological vector spaces, functional analysis, and Hilbert spaces of analytic functions

CERN Document Server

Alpay, Daniel

2015-01-01

This is an exercises book at the beginning graduate level, whose aim is to illustrate some of the connections between functional analysis and the theory of functions of one variable. A key role is played by the notions of positive definite kernel and of reproducing kernel Hilbert space. A number of facts from functional analysis and topological vector spaces are surveyed. Then, various Hilbert spaces of analytic functions are studied.

The geometry of plane waves in spaces of constant curvature

International Nuclear Information System (INIS)

Tran, H.V.

1988-01-01

We examined the geometry of possible plane wave fronts in spaces of constant curvature for three cases in which the cosmological constant is positive, zero, or negative. The cosmological constant and a second-order invariant determined by a congruence of null rays were used in the investigation. We embedded the spaces under investigation in a flat five-dimensional space, and studied the null hyperplanes passing through the origin of the flat five-dimensional space. The embedded spaces are represented by quadrics in the five-dimensional space. The plane wave fronts are represented by the intersection of the quadric with null hyperplanes passing through the origin of the five-dimensional space. We concluded that in Minkowski spaces (zero cosmological constant), the plane-fronted waves will intersect if and only if the second-order invariant mentioned above is non-zero. For deSitter spaces (positive cosmological constant), plane-fronted waves will always intersect. For anti-deSitter spaces (negative cosmological constant), plane-fronted waves may but need not intersect

Economic consequences of commercial space operations

Science.gov (United States)

Stone, Barbara A.; Wood, Peter W.

1990-01-01

The potential economic benefits generated from increased industry involvement and investment in space activities and the subsequent cost implications are discussed. A historical overview of commercial industry involvement in space is given and sources of new economic growth in space are discussed. These include communications satellites, small satellites, positioning and navigation services, space transportation and infrastructure, remote sensing, and materials processing in space such as the manufacturing of protein crystals and zeolites. Macroeconomic trends and principles such as limits on technology trade, eased restrictions on international joint ventures, foreign investments in U.S. firms, and increased foreign competition are discussed. Earth observations and mapping are considered. Opportunities for private sector involvement in building space infrastructure and space transportation are highlighted.

Relativistic positioning systems: perspectives and prospects

Science.gov (United States)

Coll Bartolomé

2013-11-01

Relativistic positioning systems are interesting technical objects for applications around the Earth and in the Solar system. But above all else, they are basic scientific objects allowing developing relativity from its own concepts. Some past and future features of relativistic positioning sys- tems, with special attention to the developments that they suggest for an epistemic relativity (relativistic experimental approach to physics), are analyzed. This includes relativistic stereometry, which, together with relativistic positioning systems, allows to introduce the general relativistic notion of (finite) laboratory (space-time region able to perform experiments of finite size).

Humans in space the psychological hurdles

CERN Document Server

Kanas, Nick

2015-01-01

Using anecdotal reports from astronauts and cosmonauts, and the results from studies conducted in space analog environments on Earth and in the actual space environment, this book broadly reviews the various psychosocial issues that affect space travelers.  Unlike other books that are more technical in format, this text is targeted for the general public.  With the advent of space tourism and the increasing involvement of private enterprise in space, there is now a need to explore the impact of space missions on the human psyche and on the interpersonal relationships of the crewmembers. Separate chapters of the book deal with psychosocial stressors in space and in space analog environments; psychological, psychiatric, interpersonal, and cultural issues pertaining to space missions; positive growth-enhancing aspects of space travel; the crew-ground interaction; space tourism; countermeasures for dealing with space; and unique aspects of a trip to Mars, the outer solar system, and interstellar travel. .

Robust Path Planning for Space Exploration Rovers

Data.gov (United States)

National Aeronautics and Space Administration — Motion planning considers the problem of moving a system from a starting position to a desired goal position. This problem has been shown to be a computationally...

Dynamic trapping of electrons in space plasmas

International Nuclear Information System (INIS)

Brenning, N.; Bohm, M.; Faelthammar, C.G.

1989-12-01

The neutralization of positive space charge is studied in a case where heavy positive ions are added to a limited region of length L in a collisionfree magnetized plasma. It is found that electrons which become accelerated towards the positive space charge can only achieve a partial neutralization: they overshoot, and the positive region becomes surrounded by negative space charges which screen the electric field from the surroundings. The process is studied both analytically and by computer simulations with consistent results: large positive potentials (U>>kT e /e) can be built up with respect to the surrounding plasma. In the process of growth, the potential maximum traps electrons in transit so that quasineutrality is maintained. The potential U is proportional to the ambient electron temperature and the square of the plasma density increase, but independent of both the ion injection rate and the length L. The process explains several features of the Porcupinge xenon beam injection experiment. It could also have importance for the electrodynamic coupling between plasmas of different densities, e.g. the injection of neutral clouds in the ionosphere of species that becomes rapidly photoionized, or penetration of dense plasma clouds from the solar wind into the magnetosphere. (31 refs.) (authors)

Geodetically resolved slip distribution of the 27 August 2012 Mw=7.3 El Salvador earthquake

Science.gov (United States)

Geirsson, H.; La Femina, P. C.; DeMets, C.; Hernandez, D. A.; Mattioli, G. S.; Rogers, R.; Rodriguez, M.

2013-12-01

On 27 August 2012 a Mw=7.3 earthquake occurred offshore of Central America causing a small tsunami in El Salvador and Nicaragua but little damage otherwise. This is the largest magnitude earthquake in this area since 2001. We use co-seismic displacements estimated from episodic and continuous GPS station time series to model the magnitude and spatial variability of slip for this event. The estimated surface displacements are small (earthquake. We use TDEFNODE to model the displacements using two different modeling approaches. In the first model, we solve for homogeneous slip on free rectangular fault(s), and in the second model we solve for distributed slip on the main thrust, realized using different slab models. The results indicate that we can match the seismic moment release, with models indicating rupture of a large area, with a low magnitude of slip. The slip is at shallow-to-intermediate depths on the main thrust off the coast of El Salvador. Additionally, we observe a deeper region of slip to the east, that reaches towards the Gulf of Fonseca between El Salvador and Nicaragua. The observed tsunami additionally indicates near-trench rupture off the coast of El Salvador. The duration of the rupturing is estimated from seismic data to be 70 s, which indicates a slow rupture process. Since the geodetic moment we obtain agrees with the seismic moment, this indicates that the earthquake was not associated with aseismic slip.

Fourier-positivity constraints on QCD dipole models

Directory of Open Access Journals (Sweden)

Bertrand G. Giraud

2016-09-01

Full Text Available Fourier-positivity (F-positivity, i.e. the mathematical property that a function has a positive Fourier transform, can be used as a constraint on the parametrization of QCD dipole-target cross-sections or Wilson line correlators in transverse position space r. They are Bessel transforms of positive transverse momentum dependent gluon distributions. Using mathematical F-positivity constraints on the limit r→0 behavior of the dipole amplitudes, we identify the common origin of the violation of F-positivity for various, however phenomenologically convenient, dipole models. It is due to the behavior r2+ϵ, ϵ>0 softer, even slightly, than color transparency. F-positivity seems thus to conflict with the present dipole formalism when it includes a QCD running coupling constant α(r.

Structural control on the Tohoku earthquake rupture process investigated by 3D FEM, tsunami and geodetic data.

Science.gov (United States)

Romano, F; Trasatti, E; Lorito, S; Piromallo, C; Piatanesi, A; Ito, Y; Zhao, D; Hirata, K; Lanucara, P; Cocco, M

2014-07-09

The 2011 Tohoku earthquake (Mw = 9.1) highlighted previously unobserved features for megathrust events, such as the large slip in a relatively limited area and the shallow rupture propagation. We use a Finite Element Model (FEM), taking into account the 3D geometrical and structural complexities up to the trench zone, and perform a joint inversion of tsunami and geodetic data to retrieve the earthquake slip distribution. We obtain a close spatial correlation between the main deep slip patch and the local seismic velocity anomalies, and large shallow slip extending also to the North coherently with a seismically observed low-frequency radiation. These observations suggest that the friction controlled the rupture, initially confining the deeper rupture and then driving its propagation up to the trench, where it spreads laterally. These findings are relevant to earthquake and tsunami hazard assessment because they may help to detect regions likely prone to rupture along the megathrust, and to constrain the probability of high slip near the trench. Our estimate of ~40 m slip value around the JFAST (Japan Trench Fast Drilling Project) drilling zone contributes to constrain the dynamic shear stress and friction coefficient of the fault obtained by temperature measurements to ~0.68 MPa and ~0.10, respectively.

GPS observations of coseismic deformation following the 2016, August 24, Mw 6 Amatrice earthquake (central Italy: data, analysis and preliminary fault model

Directory of Open Access Journals (Sweden)

Daniele Cheloni

2016-11-01

Full Text Available We used continuous Global Positioning System (GPS measurements to infer the fault geometry and the amount of coseismic slip associated to the August 24, 2016 Mw 6 Amatrice earthquake. We realized a three dimensional coseismic displacement field by combining different geodetic solutions generated by three independent analyses of the raw GPS observations. The coseismic deformation field described in this work aims at representing a consensus solution that minimizes the systematic biases potentially present in the individual geodetic solutions. Because of the limited number of stations available we modeled the measured coseismic displacements using a uniform slip model, deriving the geometry and kinematics of the causative fault, finding good agreement between our geodetically derived fault plane and other seismological and geological observations.

Phase Space Exchange in Thick Wedge Absorbers

Energy Technology Data Exchange (ETDEWEB)

Neuffer, David [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

2017-01-01

The problem of phase space exchange in wedge absorbers with ionization cooling is discussed. The wedge absorber exchanges transverse and longitudinal phase space by introducing a position-dependent energy loss. In this paper we note that the wedges used with ionization cooling are relatively thick, so that single wedges cause relatively large changes in beam phase space. Calculation methods adapted to such “thick wedge” cases are presented, and beam phase-space transformations through such wedges are discussed.

Mappings with closed range and finite dimensional linear spaces

International Nuclear Information System (INIS)

Iyahen, S.O.

1984-09-01

This paper looks at two settings, each of continuous linear mappings of linear topological spaces. In one setting, the domain space is fixed while the range space varies over a class of linear topological spaces. In the second setting, the range space is fixed while the domain space similarly varies. The interest is in when the requirement that the mappings have a closed range implies that the domain or range space is finite dimensional. Positive results are obtained for metrizable spaces. (author)

Application of dead space fraction to titrate optimal positive end-expiratory pressure in an ARDS swine model.

Science.gov (United States)

Bian, Weishuai; Chen, Wei; Chao, Yangong; Wang, Lan; Li, Liming; Guan, Jian; Zang, Xuefeng; Zhen, Jie; Sheng, Bo; Zhu, Xi

2017-04-01

This study aimed to apply the dead space fraction [ratio of dead space to tidal volume (VD/VT)] to titrate the optimal positive end-expiratory pressure (PEEP) in a swine model of acute respiratory distress syndrome (ARDS). Twelve swine models of ARDS were constructed. A lung recruitment maneuver was then conducted and the PEEP was set at 20 cm H 2 O. The PEEP was reduced by 2 cm H 2 O every 10 min until 0 cm H 2 O was reached, and VD/VT was measured after each decrement step. VD/VT was measured using single-breath analysis of CO 2 , and calculated from arterial CO 2 partial pressure (PaCO 2 ) and mixed expired CO 2 (PeCO 2 ) using the following formula: VD/VT = (PaCO 2 - PeCO 2 )/PaCO 2 . The optimal PEEP was identified by the lowest VD/VT method. Respiration and hemodynamic parameters were recorded during the periods of pre-injury and injury, and at 4 and 2 cm H 2 O below and above the optimal PEEP (Po). The optimal PEEP in this study was found to be 13.25±1.36 cm H 2 O. During the Po period, VD/VT decreased to a lower value (0.44±0.08) compared with that during the injury period (0.68±0.10) (P<0.05), while the intrapulmonary shunt fraction reached its lowest value. In addition, a significant change of dynamic tidal respiratory compliance and oxygenation index was induced by PEEP titration. These results indicate that minimal VD/VT can be used for PEEP titration in ARDS.

Geodetic mass balance measurements on debris and clean-ice tropical glaciers in Ecuador

Science.gov (United States)

La Frenierre, J.; Decker, C. R.; Jordan, E.; Wigmore, O.; Hodge, B. E.; Niederriter, C.; Michels, A.

2017-12-01

Glaciers are recognized as highly sensitive indicators of climate change in high altitude, low latitude environments. In the tropical Andes, various analyses of glacier surface area change have helped illuminate the manifestation of climate change in this region, however, information about actual glacier mass balance behavior is much more limited given the relatively small glaciers, difficult access, poor weather, and/or limited local resources common here. Several new technologies, including aerial and terrestrial LIDAR and structure-from-motion photogrammetry using small unmanned aerial vehicles (UAVs), make mass balance measurements using geodetic approaches increasingly feasible in remote mountain locations, which can both further our understanding of changing climatic conditions, and improve our ability to evaluate the downstream hydrologic impacts of ice loss. At Volcán Chimborazo, Ecuador, these new technologies, combined with a unique, 5-meter resolution digital elevation model derived from 1997 aerial imagery, make possible an analysis of the magnitude and spatial patterns of mass balance behavior over the past two decades. Here, we evaluate ice loss between 1997 and 2017 at the tongues of two adjacent glaciers, one debris-covered and detached from its accumulation area (Reschreiter Glacier), and one debris-free and intact (Hans Meyer Glacier). Additionally, we incorporate data from 2012 and 2013 terrestrial LIDAR surveys to evaluate the behavior of the Reschreiter at a finer temporal resolution. We find that on the Hans Meyer, the mean surface deflation rate since 1997 at the present-day tongue has been nearly 3 m yr-1, while on the lower-elevation Reschreiter, the mean deflation rate has been approximately 1 m yr-1. However, the processes by which debris-covered ice becomes exposed results in highly heterogeneous patterns of ice loss, with some areas experiencing surface deflation rates approaching 15 m yr-1 when energy absorption is unimpeded.

Geodetic integration of Sentinel-1A IW data using PSInSAR in Hungary

Science.gov (United States)

Farkas, Péter; Hevér, Renáta; Grenerczy, Gyula

2015-04-01

ESA's latest Synthetic Aperture Radar (SAR) mission Sentinel-1 is a huge step forward in SAR interferometry. With its default acquisition mode called the Interferometric Wide Swath Mode (IW) areas through all scales can be mapped with an excellent return time of 12 days (while only the Sentinel-1A is in orbit). Its operational data policy is also a novelty, it allows scientific users free and unlimited access to data. It implements a new type of ScanSAR mode called Terrain Observation with Progressive Scan (TOPS) SAR. It has the same resolution as ScanSAR but with better signal-to-noise ratio distribution. The bigger coverage is achieved by rotation of the antenna in the azimuth direction, therefore it requires very precise co-registration because even errors under a pixel accuracy can introduce azimuth phase variations caused by differences in Doppler-centroids. In our work we will summarize the benefits and the drawbacks of the IW mode. We would like to implement the processing chain of GAMMA Remote Sensing of such data for mapping surface motion with special attention to the co-registration step. Not only traditional InSAR but the advanced method of Persistent Scatterer InSAR (PSInSAR) will be performed and presented as well. PS coverage, along with coherence, is expected to be good due to the small perpendicular and temporal baselines. We would also like to integrate these measurements into national geodetic networks using common reference points. We have installed trihedral corner reflectors at some selected sites to aid precise collocation. Thus, we aim to demonstrate that Sentinel-1 can be effectively used for surface movement detection and monitoring and it can also provide valuable information for the improvement of our networks.

The eigenvalue problem in phase space.

Science.gov (United States)

Cohen, Leon

2018-06-30

We formulate the standard quantum mechanical eigenvalue problem in quantum phase space. The equation obtained involves the c-function that corresponds to the quantum operator. We use the Wigner distribution for the phase space function. We argue that the phase space eigenvalue equation obtained has, in addition to the proper solutions, improper solutions. That is, solutions for which no wave function exists which could generate the distribution. We discuss the conditions for ascertaining whether a position momentum function is a proper phase space distribution. We call these conditions psi-representability conditions, and show that if these conditions are imposed, one extracts the correct phase space eigenfunctions. We also derive the phase space eigenvalue equation for arbitrary phase space distributions functions. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Position indication apparatus

Energy Technology Data Exchange (ETDEWEB)

Masuda, T

1964-02-24

A plurality of magnetically operated switches are spaced equally in the hollow tube of a control rod actuating mechanism. One side of each switch is connected, via a low resistance, to a corresponding tap of a low resistance voltage divider network consisting of an equivalent number of low resistance sections with the opposite side of each switch connected to a common conducting wire A. To both ends of the voltage dividing network are connected, respectively, conducting wires B and C. Wires A, B, and C are further coupled to a fuel rod position indicator comprising a voltmeter and power source external to the control rod actuating member. The control rod actuating member is adapted to slide in the hollow tube so that switches passing a position facing a magnet secured to the lower end of the actuating member are rendered closed. Hence, the position of the control rod may be read by reading the voltage off the meter.

Map projections cartographic information systems

CERN Document Server

Grafarend, Erik W

2006-01-01

In the context of Geographical Information Systems (GIS) the book offers a timely review of map projections (sphere, ellipsoid, rotational surfaces) and geodetic datum transformations. For the needs of photogrammetry, computer vision, and remote sensing space projective mappings are reviewed.

How to spy on your neighbor's water consumption from space

Science.gov (United States)

Neely, W.; Borsa, A. A.; Burney, J. A.

2017-12-01

Dependence on groundwater has increased in the agricultural production regions of California's Central Valley due to recent and persistent droughts. To protect the long-term reliability of groundwater resources in California, the state passed the Sustainable Groundwater Management Act (SGMA) in September 2014. In situ observation of subsurface reservoir levels is ideal for monitoring aquifer health at a water district scale, but is limited by the low density of monitoring wells and temporal gaps between measurements. An alternative to well measurements relies on the fact that groundwater extraction may lead to surface subsidence due to the compaction of the aquifer at depth. Such surface displacements can be resolved using geodetic techniques. We present an integrative approach using Interferometric Synthetic Aperture Radar (InSAR) and continuous Global Positioning System (cGPS) station observations to characterize surface deformation related to extensive pumping at a farm-level resolution every 12-24 days. We demonstrate our technique in the southern Central Valley where we observe subsidence upwards of 25 cm/yr from late 2014 to early 2017. Our methods offer an inexpensive supplement to in situ measurements that allows for the detection and deterrence of water mismanagement.

Urban Spaces and Safety

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Rosa Grazia De Paoli

2012-11-01

Full Text Available The concept of vulnerability understood in the traditional sense as a “single manufactured good” is insufficient when it comes to describing the real conditions of an urban system’s vulnerability within which an indefinite variable of factors interact with one another thereby determining the damage caused by an earthquake. These interacting factors constitute so-called “urban vulnerability” which town planners use in order to contribute to the field in the form of analysis definition and interventions in the mitigation of seismic risk on an urban scale. The research paper “Relational Spaces as Safe Places” positions itself firmly in the vein of town planning research which focuses on the mitigation of seismic risk, and which intends to blaze a new methodological trail that aims to identify safety traits in urban spaces. The research paper’s starting point is the assumption that empty urban spaces, given the indications provided by the principal organs for Civic Protection, have come to be seen as the spaces designed to accommodate the public in cases of emergency. This can generate new thought regarding town planning by reviewing early post-earthquake urban designs where the rules were laid out for earthquake-proof cities: a “chessboard” plan with wide streets, both straight and perpendicular, empty spaces like squares and markets positioned along the longitudinal streets, and buildings with regular layouts all at right-angles. These simple guidelines, which are often disregarded and distorted in modern towns, are extraordinarily relevant and oriented towards new definitions of the urban traits of quality and security.

Noncommutative Phase Spaces by Coadjoint Orbits Method

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Ancille Ngendakumana

2011-12-01

Full Text Available We introduce noncommutative phase spaces by minimal couplings (usual one, dual one and their mixing. We then realize some of them as coadjoint orbits of the anisotropic Newton-Hooke groups in two- and three-dimensional spaces. Through these constructions the positions and the momenta of the phase spaces do not commute due to the presence of a magnetic field and a dual magnetic field.

Wiener-Hopf operators on spaces of functions on R+ with values in a Hilbert space