Performance Analysis of Several GPS/Galileo Precise Point Positioning Models.

Science.gov (United States)

Afifi, Akram; El-Rabbany, Ahmed

2015-06-19

This paper examines the performance of several precise point positioning (PPP) models, which combine dual-frequency GPS/Galileo observations in the un-differenced and between-satellite single-difference (BSSD) modes. These include the traditional un-differenced model, the decoupled clock model, the semi-decoupled clock model, and the between-satellite single-difference model. We take advantage of the IGS-MGEX network products to correct for the satellite differential code biases and the orbital and satellite clock errors. Natural Resources Canada's GPSPace PPP software is modified to handle the various GPS/Galileo PPP models. A total of six data sets of GPS and Galileo observations at six IGS stations are processed to examine the performance of the various PPP models. It is shown that the traditional un-differenced GPS/Galileo PPP model, the GPS decoupled clock model, and the semi-decoupled clock GPS/Galileo PPP model improve the convergence time by about 25% in comparison with the un-differenced GPS-only model. In addition, the semi-decoupled GPS/Galileo PPP model improves the solution precision by about 25% compared to the traditional un-differenced GPS/Galileo PPP model. Moreover, the BSSD GPS/Galileo PPP model improves the solution convergence time by about 50%, in comparison with the un-differenced GPS PPP model, regardless of the type of BSSD combination used. As well, the BSSD model improves the precision of the estimated parameters by about 50% and 25% when the loose and the tight combinations are used, respectively, in comparison with the un-differenced GPS-only model. Comparable results are obtained through the tight combination when either a GPS or a Galileo satellite is selected as a reference.

GPS measurements in Satakunta area

International Nuclear Information System (INIS)

Poutanen, M.; Nyberg, S.; Ahola, J.

2010-10-01

The Finnish Geodetic Institute, the Geological Survey of Finland, Posiva Ltd and municipalities in the district of Satakunta launched the GeoSatakunta research program in 2002 to carry out interdisciplinary studies on regional bedrock stress field and to apply the results e.g. in land use planning in the Satakunta area. The area was chosen for many reasons. Its geological diversity, extensive multi-disciplinary data coverage, and various interests of participants made the area suitable for the project. The purpose of the GPS observations is to get detailed information on recent crustal deformations in the area. The Finnish Geodetic Institute maintains e.g. national GPS network, FinnRef, and since 1995 a local research network in the Olkiluoto area. The Satakunta network differs from these, and this is the first time to obtain such detailed information of a regional network in Finland. The Satakunta GPS network consists of 13 concrete pillars for episodic GPS campaigns and the Olkiluoto permanent GPS station in the FinnRef network. The distances between the concrete pillars are 10-15 km, and the sites were chosen in a co-operation with the Geological Survey of Finland taking into account the geological structures in the area. The City of Pori made the final reconnaissance in the field and constructed eight pillars in 2003. The original network was expanded in 2005-2006 in Eurajoki and Rauma, and at the City of Rauma joined the co-operation. The five new pillars join the previous Olkiluoto network into the Satakunta network. There have been three annual GPS campaigns in 2003-2008. Time series of the Satakunta network are shorter than in the Olkiluoto network, and also the distances are longer. Therefore, the same accuracy than in Olkiluoto has not yet achieved. However, mm-sized movements can be excluded. Estimated velocities were small (0.2 mm/a) and mostly statistically insignificant because of relatively short time series. In this publication we describe the

Forsmark site investigation. A deformation analysis of the Forsmark GPS monitoring network from 2005 to 2009

Energy Technology Data Exchange (ETDEWEB)

Gustafson, Lars; Ljungberg, Annika (Caliterra AB (Sweden))

2010-10-15

The objective of the study is to identify possible movements in the bedrock within and outside the candidate area at Forsmark. Seven physically stable stations were built in the Forsmark area in the autumn of 2005. Stations were established within a ten-kilometer radius. The stations were placed in three different areas separated by regional deformation zones: NE of the Singoe zone, within the candidate area, and SW of the Forsmark zone. Data have been collected in eighteen campaigns, each with a duration of about five days, from November 2005 to December 2009. Stations consist of a stainless steel rod fixed in the bedrock on which the GPS antenna mounts. Each station has dedicated GPS equipment only used at the specific site. Sets consist of a GPS receiver collecting raw GPS data and a choke ring antenna linked to the receiver using a coaxial cable. The receivers and antennas are dual frequency high precision geodetic grade. During each campaign the GPS receiver saves a reading every second for the duration of the five days campaign. The antennas remain mounted on the stations during the entire project, whereas all other equipment is in place at the station only during the campaigns. The measurements were related to the SWEPOS network stations Lovoe, Uppsala and Maartsbo that are defined as stations with stable fundaments by the National Land Survey of Sweden (Lantmaeteriet). This report deals with altogether 18 campaigns. The first 13 campaigns were performed during the period November 2005 to August 2008. However, the number of campaigns has been extended by adding a fourth year to the project. Optimization of the data processing depends on the properties of the entire data set comprising a period of four years. We divided the data into periods of 24 hours with each period processed as a separate session in the Bernese post processing software, after which we analyzed the residuals to conclude that data are of the expected quality. The entire data set from four

A Demonstration of GPS Landslide Monitoring Using Online Positioning User Service (OPUS)

Science.gov (United States)

Wang, G.

2011-12-01

Global Positioning System (GPS) technologies have been frequently applied to landslide study, both as a complement, and as an alternative to conventional surveying methods. However, most applications of GPS for landslide monitoring have been limited to the academic community for research purposes. High-accuracy GPS has not been widely equipped in geotechnical companies and used by technicians. The main issue that limits the applications of GPS in the practice of high-accuracy landslide monitoring is the complexity of GPS data processing. This study demonstrated an approach using the Online Positioning User Service (OPUS) (http://www.ngs.noaa.gov/OPUS) provided by the National Geodetic Survey (NGS) of National Oceanic and Atmospheric Administration (NOAA) to process GPS data and conduct long-term landslide monitoring in the Puerto Rico and Virgin Islands Region. Continuous GPS data collected at a creeping landslide site during two years were used to evaluate different scenarios for landslide surveying: continuous or campaign, long duration or short duration, morning or afternoon (different weather conditions). OPUS uses Continuously Operating Reference Station (CORS) managed by NGS (http://www.ngs.noaa.giv/CORS/) as references and user data as a rover to solve a position. There are 19 CORS permanent GPS stations in the Puerto Rico and Virgin Islands region. The dense GPS network provides a precise and reliable reference frame for subcentimeter-accuracy landslide monitoring in this region. Our criterion for the accuracy was the root-mean-square (RMS) of OPUS solutions over a 2-year period with respect to true landslide displacement time series overt the same period. The true landslide displacements were derived from a single-baseline (130 m) GPS processing by using 24-hour continuous data. If continuous GPS surveying is performed in the field, then OPUS static processing can provide 0.6 cm horizontal and 1.1 cm vertical precision with few outliers. If repeated

Quality analysis of the campaign GPS stations observation in Northeast and North China

Directory of Open Access Journals (Sweden)

Yaxuan Hu

2016-03-01

Full Text Available TEQC is used to check the observations quality of 173 GPS campaign stations in the Northeast and North China. Each station was observed with an occupation of 4 days. The quality of the 692 data files is analyzed by the ratio of overall observations to possible observations, MP1, MP2 and the ratio of observations to slips. The reasons for multipath and cycle slips can be derived from the photos taken in the field. The results show that the coverage of trees and buildings/structures, and the interference of high-voltage power lines near the stations are the main reasons. In a small area, the horizontal velocity field in the period 2011–2013 is exemplified, where the magnitudes and directions of the 4 stations' rates are clearly different with that of other stations. It seems that the error caused by the worse environment cannot be mitigated through post processing. Therefore, these conclusions can help the establishment of GNSS stations, measurements, data processing and formulating standards in future.

Using GPS to evaluate productivity and performance of forest machine systems

Science.gov (United States)

Steven E. Taylor; Timothy P. McDonald; Matthew W. Veal; Ton E. Grift

2001-01-01

This paper reviews recent research and operational applications of using GPS as a tool to help monitor the locations, travel patterns, performance, and productivity of forest machines. The accuracy of dynamic GPS data collected on forest machines under different levels of forest canopy is reviewed first. Then, the paper focuses on the use of GPS for monitoring forest...

GPS operations at Olkiluoto in 2009

Energy Technology Data Exchange (ETDEWEB)

Kallio, U.; Nyberg, S.; Koivula, H.; Jokela, J.; Poutanen, M.; Ahola, J. (Finnish Geodetic Institute, Masala (Finland))

2010-06-15

The GPS based deformation studies have been made at the investigation areas of Posiva since 1995, when the network of ten GPS pillars was established at Olkiluoto. One pillar in the investigation area belongs to the Finnish permanent GPS network, FinnRef. 28 GPS measurement campaigns have been carried out at Olkiluoto since 1995. According to the time series of the GPS results 1/3 of the baselines at Olkiluoto have statistically significant change rates. However, the observed movements are smaller than +-0.20 mm/a. There are five pillars, which have statistically significant horizontal velocities at Olkiluoto. These local velocity components are small but taking into account the standard deviations the largest velocity components seems to be reliably determined. At Olkiluoto a baseline for electronic distance measurements (EDM) was built in 2002. The baseline has been measured using EDM instruments in connection to the GPS observations. Changes in he difference between the GPS and EDM results indicate the systematic change in GPS results. No corrections based on only one baseline were not applied to GPS vectors. The GPS network at Olkiluoto was extended in 2003. The new pillars were built close to Kuivalahti village and on a small island of Iso Pyrekari. According to the geological evidence it is expected that a fracture zone is located between the new stations, thus enabling the determination of possible deformations along the fracture zone. The new pillars have been observed since 2003 and now we have computed the first deformation analysis from the six years data. Four new permanent stations will be established in summer 2010 at Olkiluoto. We have automated the processing of the campaign data by using the Bernese processing engine (BPE) together with our own Perl scripts. The local crustal deformations have been studied in GeoSatakunta project, too. This GPS network is located in Cities of Pori and Rauma and their neighbouring municipalities. Two new pillars

GPS operations at Olkiluoto in 2009

International Nuclear Information System (INIS)

Kallio, U.; Nyberg, S.; Koivula, H.; Jokela, J.; Poutanen, M.; Ahola, J.

2010-06-01

The GPS based deformation studies have been made at the investigation areas of Posiva since 1995, when the network of ten GPS pillars was established at Olkiluoto. One pillar in the investigation area belongs to the Finnish permanent GPS network, FinnRef. 28 GPS measurement campaigns have been carried out at Olkiluoto since 1995. According to the time series of the GPS results 1/3 of the baselines at Olkiluoto have statistically significant change rates. However, the observed movements are smaller than ±0.20 mm/a. There are five pillars, which have statistically significant horizontal velocities at Olkiluoto. These local velocity components are small but taking into account the standard deviations the largest velocity components seems to be reliably determined. At Olkiluoto a baseline for electronic distance measurements (EDM) was built in 2002. The baseline has been measured using EDM instruments in connection to the GPS observations. Changes in he difference between the GPS and EDM results indicate the systematic change in GPS results. No corrections based on only one baseline were not applied to GPS vectors. The GPS network at Olkiluoto was extended in 2003. The new pillars were built close to Kuivalahti village and on a small island of Iso Pyrekari. According to the geological evidence it is expected that a fracture zone is located between the new stations, thus enabling the determination of possible deformations along the fracture zone. The new pillars have been observed since 2003 and now we have computed the first deformation analysis from the six years data. Four new permanent stations will be established in summer 2010 at Olkiluoto. We have automated the processing of the campaign data by using the Bernese processing engine (BPE) together with our own Perl scripts. The local crustal deformations have been studied in GeoSatakunta project, too. This GPS network is located in Cities of Pori and Rauma and their neighbouring municipalities. Two new pillars

Evaluation of the crustal deformations in the northern region of Lake Nasser (Egypt) derived from 8 years of GPS campaign observations

Science.gov (United States)

Rayan, A.; Fernandes, R. M. S.; Khalil, H. A.; Mahmoud, S.; Miranda, J. M.; Tealab, A.

2010-04-01

The proper evaluation of crustal deformations in the Aswan (Egypt) region is crucial due to the existence of one major artificial structure: the Aswan High Dam. This construction induced the creation of one of the major artificial lakes: Lake Nasser, which has a surface area of about 5200 km 2 with a maximum capacity of 165 km 3. The lake is nearly 550 km long (more than 350 km within Egypt and the remainder in Sudan) and 35 km across at its widest point. Great attention has focused on this area after the November 14, 1981 earthquake ( ML = 5.7), with its epicenter southwest of the High Dam. In order to evaluate the present-day kinematics of the region, its relationship with increasing seismicity, and the possible influence of the Aswan High Dam operation, a network of 11 GPS sites was deployed in the area. This network has been reobserved every year since 2000 in campaign style. We present here the results of the analysis of the GPS campaign time-series. These time-series are already long enough to derive robust solutions for the motions of these stations. The computed trends are analyzed within the framework of the geophysical and geological settings of this region. We show that the observed displacements are significant, pointing to a coherent intraplate extensional deformation pattern, where some of the major faults (e.g., dextral strike-slip Kalabsha fault and normal Dabud fault) correspond to gradients of the surface deformation field. We also discuss the possible influence of the water load on the long-term deformation pattern.

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.

GPS water vapor project associated to the ESCOMPTE programme: description and first results of the field experiment

Science.gov (United States)

Bock, O.; Doerflinger, E.; Masson, F.; Walpersdorf, A.; Van-Baelen, J.; Tarniewicz, J.; Troller, M.; Somieski, A.; Geiger, A.; Bürki, B.

A dense network of 17 dual frequency GPS receivers has been operated for two weeks during June 2001 within a 20 km × 20 km area around Marseille, France, as part of the ESCOMPTE field campaign ([Cros et al., 2004. The ESCOMPTE program: an overview. Atmos. Res. 69, 241-279]; http://medias.obs-mip.fr/escompte). The goal of this GPS experiment was to provide GPS data allowing for tomographic inversions and their validation within a well-documented observing period (the ESCOMPTE campaign). Simultaneous water vapor radiometer, solar spectrometer, Raman lidar and radiosonde data are used for comparison and validation. In this paper, we highlight the motivation, issues and describe the GPS field experiment. Some first results of integrated water vapor retrievals from GPS and the other sensing techniques are presented. The strategies for GPS data processing and tomographic inversions are discussed.

Campaigned GPS on Present-Day Crustal Deformation in Northernmost Longitudinal Valley Preliminary Results, Hualien Taiwan

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Chia-Yu Chen

2014-01-01

Full Text Available The Longitudinal Valley in Eastern Taiwan sits at the collision suture between the Eurasian and Philippine Sea plates. Based on repeated GPS campaigned measurements from 25 stations six times in 2007 - 2009, we characterize the surface deformation in the northernmost Longitudinal Valley where the Coastal Range of the Philippine Sea plate turns northward diving under the Eurasian plate producing two major active faults: the Milun fault and the Longitudinal Valley fault. We reconstructed a GPS velocity field and conducted strain analyses and elastic block modeling. Our results suggest a rapid clockwise rotation of 33° Myr-1 and an eastward tectonic escape in the small Hualien City block (HUAL area of ~10 × 10 km, which is apparently detached from the regional rotating RYUK block defined by previous studies. We interpret it as being initiated locally by the northwest indentation of the Coastal Range, which pushed the HUAL block to move upward and eastward. According to our strain analyses, the HUAL block shows a significant internal elastic strain inside the Milun Tableland, the hanging wall of the Milun fault. No significant deformation was observed across the surface trace of the fault, indicating that the Milun fault is now probably locked in the near surface. The deformation in the footwall of the fault was accommodated by pure-shear strain with a major NNW-compression and a minor ENE-extension. The deformation in the hanging wall is characterized by simple-shear strain with ENE-extension in its northern part and little deformation in the southern part, separated by a little known NW-trending active fault zone (Dongmingyi fault, which needs further investigation.

GPS radio collar 3D performance as influenced by forest structure and topography

Science.gov (United States)

R. Scott Gamo; Mark A. Rumble; Fred Lindzey; Matt Stefanich

2000-01-01

Global Positioning System (GPS) telemetry enables biologists to obtain accurate and systematic locations of animals. Vegetation can block signals from satellites to GPS radio collars. Therefore, a vegetation dependent bias to telemetry data may occur which if quantified, could be accounted for. We evaluated the performance of GPS collars in 6 structural stage...

GPS Operations at Olkiluoto, Kivetty and Romuvaara in 2005

International Nuclear Information System (INIS)

Ahola, J.; Ollikainen, M.; Koivula, H.; Jokela, J.

2006-07-01

The GPS based deformation studies has been made at the investigation areas of Posiva since 1995, when the network of ten GPS pillars was established at Olkiluoto. The network of seven GPS pillars was built at Kivetty and Romuvaara during the year 1996. One pillar in each investigation area belongs to the Finnish permanent GPS network, FinnRef. Twenty GPS measurement campaigns have been carried out at Olkiluoto since 1995, and fourteen campaigns at Kivetty and Romuvaara. According to the time series of the GPS results 1/3 of the baselines at Olkiluoto have statistically significant change rates. However, the observed movements are smaller than ± 0.22 mm/a. There are no statistically signicant movements at Kivetty and Romuvaara expect one pillar at Romuvaara. There are five pillars, which have statistically significant horizontal velocities at Olkiluoto. The local velocity components are small but taking into account the standard deviations the largest velocity components seems to be reliable (maximum velocity is - 0.25 mm/a ± 0.025 mm/a). The uniform scale for the GPS measurements made in different years is the basic condition for reliable results in the deformation analyses. At Olkiluoto a baseline for electronic distance measurements (EDM) was built in 2002. The baseline has been measured using EDM instruments simultaneously with the GPS observations. The comparison between the GPS and EDM results to show a possible scale error of the GPS. The GPS network at Olkiluoto was enlarged in 2003. The new pillars were built close to Kuivalahti village and on a small island of Iso Pyrekari, both north from Olkiluoto. According to the geological evidence it is expected that a fracture zone is located between the new stations, thus enabling the determination of possible deformations along the fracture zone. The new pillars have been observed five times since 2003, but the time series are still too short for reliable deformation studies. Including the new pillars the local

Quality control of GPS deformation data from Forsmark and analysis of crustal deformation in the local scale

International Nuclear Information System (INIS)

Ekman, Lennart; Ekman, Mats

2013-03-01

A network comprising seven GPS stations was established at Forsmark, Sweden, within about 10 km radius from the centre of the investigation area for a final repository for spent nuclear fuel with the purpose of monitoring slow rock motion. During the period November 2005 to December 2009, GPS data were collected in eighteen intermittent measurement campaigns, each with a duration of between three and seven days. As shown in Gustafson and Ljungberg (2010), the data expose a considerable scatter, indicating a non-linear variability of the GPS baseline velocities. However, the commission narrated in Gustafson and Ljungberg (2010) was restricted to account only for the field performance of the GPS measurement campaign and to present the resulting measurement data per se, merely supplemented with a linear regression solution for the baseline motions. The preliminary interpretation of GPS data in Gustafson and Ljungberg (2010) was in the present report followed by a closer examination where the non-linear variability is modelled as sinusoidal. Evidence for sinusoidal variations were also found in resulting data from GPS measurements at the Aespoe/Laxemar area at Oskarshamn (Sjoeberg et al. 2004), as well as in GPS data from several sites in western, middle and north-eastern Finland (Ollikainen et al. 2004, Ahola et al. 2008, Poutanen et al. 2010). We here postulate that the baseline velocities are characterized by a long-term linear drift superposed by a non-linear sinusoidal motion. This was modelled in two steps. Initially an Auto Regressive (AR) model was applied and the linear trends between the GPS stations were estimated. In a second step, an Auto Regressive Moving Average (ARMA) model was estimated for (almost) all baselines. The residuals between the original data and the one-step predictor for the ARMA model were then used to estimate new linear trends for the baselines. Our analysis of the Forsmark GPS data indicates relative motions more than 10 times slower

Quality control of GPS deformation data from Forsmark and analysis of crustal deformation in the local scale

Energy Technology Data Exchange (ETDEWEB)

Ekman, Lennart; Ekman, Mats [LE Geokonsult AB, Baelinge (Sweden)

2013-03-15

A network comprising seven GPS stations was established at Forsmark, Sweden, within about 10 km radius from the centre of the investigation area for a final repository for spent nuclear fuel with the purpose of monitoring slow rock motion. During the period November 2005 to December 2009, GPS data were collected in eighteen intermittent measurement campaigns, each with a duration of between three and seven days. As shown in Gustafson and Ljungberg (2010), the data expose a considerable scatter, indicating a non-linear variability of the GPS baseline velocities. However, the commission narrated in Gustafson and Ljungberg (2010) was restricted to account only for the field performance of the GPS measurement campaign and to present the resulting measurement data per se, merely supplemented with a linear regression solution for the baseline motions. The preliminary interpretation of GPS data in Gustafson and Ljungberg (2010) was in the present report followed by a closer examination where the non-linear variability is modelled as sinusoidal. Evidence for sinusoidal variations were also found in resulting data from GPS measurements at the Aespoe/Laxemar area at Oskarshamn (Sjoeberg et al. 2004), as well as in GPS data from several sites in western, middle and north-eastern Finland (Ollikainen et al. 2004, Ahola et al. 2008, Poutanen et al. 2010). We here postulate that the baseline velocities are characterized by a long-term linear drift superposed by a non-linear sinusoidal motion. This was modelled in two steps. Initially an Auto Regressive (AR) model was applied and the linear trends between the GPS stations were estimated. In a second step, an Auto Regressive Moving Average (ARMA) model was estimated for (almost) all baselines. The residuals between the original data and the one-step predictor for the ARMA model were then used to estimate new linear trends for the baselines. Our analysis of the Forsmark GPS data indicates relative motions more than 10 times slower

Performance evaluation of GPS receiver under equatorial scintillation

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Alison de Oliveira Moraes

2009-06-01

Full Text Available Equatorial scintillation is a phenomenon that occurs daily in the equatorial region after the sunset and affects radio signals that propagate through the ionosphere. Depending on the temporal and spatial situation, equatorial scintillation can represent a problem in the availability and precision of the Global Positioning System (GPS. This work is concerned with evaluating the impact of equatorial scintillation on the performance of GPS receivers. First, the morphology and statistical model of equatorial scintillation is briefly presented. A numerical model that generates synthetic scintillation data to simulate the effects of equatorial scintillation is presented. An overview of the main theoretical principles on GPS receivers is presented. The analytical models that describe the effects of scintillation at receiver level are presented and compared with numerical simulations using a radio software receiver and synthetic data. The results achieved by simulation agreed quite well with those predicted by the analytical models. The only exception is for links with extreme levels of scintillation and when weak signals are received.

Study of the active deformation of Mitidja (Tell Atlas, Algeria) by GPS

Science.gov (United States)

Bacha, Wahab; Masson, Frederic; Yelles-Chaouche, Abdelkrim; Lammali, Kamel; Bellik, Amar; Hamai, Lamine

2013-04-01

A network was created in the Mitidja region around the capital Algiers (Algeria). It has been established to study the deformation of the region and the slow operation of flaws in it. The network was installed by a distribution of GPS stations according to structural domains existing in the region. Twelve bases spread across the study area, have been installed. The measurements were acquired by performing four measurement campaigns in 2006, 2007, 2009 and 2010, with sessions over a month of action. This work allowed the installation of a geodetic network of regional monitoring by methodology GPS in the zone of Mitidja (Tellian Atlas, Algeria). Four observation campaigns were carried out on this area with session's superiors in one month of measurements. The treatment was carried out with software GAMIT-GLOBK, the network is attached to several world stations IGS treated between 2000-2010, indexed in a precise frame of reference ITRF05. The results presented in this memory show a deformation in shortening ≤ 0.5 mm/an in the plain of Mitidja and the surrounding Solid masses.

Combined GPS/GLONASS Precise Point Positioning with Fixed GPS Ambiguities

Science.gov (United States)

Pan, Lin; Cai, Changsheng; Santerre, Rock; Zhu, Jianjun

2014-01-01

Precise point positioning (PPP) technology is mostly implemented with an ambiguity-float solution. Its performance may be further improved by performing ambiguity-fixed resolution. Currently, the PPP integer ambiguity resolutions (IARs) are mainly based on GPS-only measurements. The integration of GPS and GLONASS can speed up the convergence and increase the accuracy of float ambiguity estimates, which contributes to enhancing the success rate and reliability of fixing ambiguities. This paper presents an approach of combined GPS/GLONASS PPP with fixed GPS ambiguities (GGPPP-FGA) in which GPS ambiguities are fixed into integers, while all GLONASS ambiguities are kept as float values. An improved minimum constellation method (MCM) is proposed to enhance the efficiency of GPS ambiguity fixing. Datasets from 20 globally distributed stations on two consecutive days are employed to investigate the performance of the GGPPP-FGA, including the positioning accuracy, convergence time and the time to first fix (TTFF). All datasets are processed for a time span of three hours in three scenarios, i.e., the GPS ambiguity-float solution, the GPS ambiguity-fixed resolution and the GGPPP-FGA resolution. The results indicate that the performance of the GPS ambiguity-fixed resolutions is significantly better than that of the GPS ambiguity-float solutions. In addition, the GGPPP-FGA improves the positioning accuracy by 38%, 25% and 44% and reduces the convergence time by 36%, 36% and 29% in the east, north and up coordinate components over the GPS-only ambiguity-fixed resolutions, respectively. Moreover, the TTFF is reduced by 27% after adding GLONASS observations. Wilcoxon rank sum tests and chi-square two-sample tests are made to examine the significance of the improvement on the positioning accuracy, convergence time and TTFF. PMID:25237901

Combined GPS/GLONASS Precise Point Positioning with Fixed GPS Ambiguities

Directory of Open Access Journals (Sweden)

Lin Pan

2014-09-01

Full Text Available Precise point positioning (PPP technology is mostly implemented with an ambiguity-float solution. Its performance may be further improved by performing ambiguity-fixed resolution. Currently, the PPP integer ambiguity resolutions (IARs are mainly based on GPS-only measurements. The integration of GPS and GLONASS can speed up the convergence and increase the accuracy of float ambiguity estimates, which contributes to enhancing the success rate and reliability of fixing ambiguities. This paper presents an approach of combined GPS/GLONASS PPP with fixed GPS ambiguities (GGPPP-FGA in which GPS ambiguities are fixed into integers, while all GLONASS ambiguities are kept as float values. An improved minimum constellation method (MCM is proposed to enhance the efficiency of GPS ambiguity fixing. Datasets from 20 globally distributed stations on two consecutive days are employed to investigate the performance of the GGPPP-FGA, including the positioning accuracy, convergence time and the time to first fix (TTFF. All datasets are processed for a time span of three hours in three scenarios, i.e., the GPS ambiguity-float solution, the GPS ambiguity-fixed resolution and the GGPPP-FGA resolution. The results indicate that the performance of the GPS ambiguity-fixed resolutions is significantly better than that of the GPS ambiguity-float solutions. In addition, the GGPPP-FGA improves the positioning accuracy by 38%, 25% and 44% and reduces the convergence time by 36%, 36% and 29% in the east, north and up coordinate components over the GPS-only ambiguity-fixed resolutions, respectively. Moreover, the TTFF is reduced by 27% after adding GLONASS observations. Wilcoxon rank sum tests and chi-square two-sample tests are made to examine the significance of the improvement on the positioning accuracy, convergence time and TTFF.

Positioning performance of the NTCM model driven by GPS Klobuchar model parameters

Science.gov (United States)

Hoque, Mohammed Mainul; Jakowski, Norbert; Berdermann, Jens

2018-03-01

Users of the Global Positioning System (GPS) utilize the Ionospheric Correction Algorithm (ICA) also known as Klobuchar model for correcting ionospheric signal delay or range error. Recently, we developed an ionosphere correction algorithm called NTCM-Klobpar model for single frequency GNSS applications. The model is driven by a parameter computed from GPS Klobuchar model and consecutively can be used instead of the GPS Klobuchar model for ionospheric corrections. In the presented work we compare the positioning solutions obtained using NTCM-Klobpar with those using the Klobuchar model. Our investigation using worldwide ground GPS data from a quiet and a perturbed ionospheric and geomagnetic activity period of 17 days each shows that the 24-hour prediction performance of the NTCM-Klobpar is better than the GPS Klobuchar model in global average. The root mean squared deviation of the 3D position errors are found to be about 0.24 and 0.45 m less for the NTCM-Klobpar compared to the GPS Klobuchar model during quiet and perturbed condition, respectively. The presented algorithm has the potential to continuously improve the accuracy of GPS single frequency mass market devices with only little software modification.

Purex process operation and performance: 1970 thoria campaign

International Nuclear Information System (INIS)

Walser, R.L.

1978-02-01

The Hanford Purex Plant has demonstrated suitability for reprocessing irradiated thoria (ThO 2 ) target elements on a campaign basis. A 1965 process test and major production campaigns conducted in 1966 and 1970 recovered nitrate solution form products totaling approximately 565 tons of thorium and 820 kilograms of 233 U. The overall recoveries for the 1970 campaign based on reactor input data were 94.9 percent for thorium and 95.2 percent for uranium. The primary function of the Hanford Purex Plant is reprocessing of irradiated uranium fuel elements to separate and purify uranium, plutonium and neptunium. Converting the plant to thoria reprocessing required major process development work and equipment modifications. The operation and performance of the Plant during the 1970 thoria reprocessing campaign is discussed in this report. The discussion includes background information on the process and equipment, problems encountered, and changes recommended for future campaigns

Hacking GPS

CERN Document Server

Kingsley-Hughes, Kathie

2005-01-01

* This is the "user manual" that didn't come with any of the 30 million GPS receivers currently in use, showing readers how to modify, tweak, and hack their GPS to take it to new levels!* Crazy-cool modifications include exploiting secret keycodes, revealing hidden features, building power cords and cables, hacking the battery and antenna, protecting a GPS from impact and falls, making a screen protector, and solar-powering a GPS* Potential power users will take the function and performance of their GPS to a whole new level by hacking into the firmware and hacking into a PC connection with a GPS* Fear not! Any potentially dangerous mod (to the device) is clearly labeled, with precautions listed that should be taken* Game time! Readers can check out GPS games, check into hacking geocaching, and even use a GPS as a metal detector

Developing a GPS-based truck freight performance measure platform.

Science.gov (United States)

2010-05-01

Although trucks move the largest volume and value of goods in urban areas, relatively little is known about their travel : patterns and how the roadway network performs for trucks. Global positioning systems (GPS) used by trucking : companies to mana...

GPS operations at Olkiluoto, Kivetty and Romuvaara in 2008

International Nuclear Information System (INIS)

Kallio, U.; Ahola, J.; Koivula, H.; Jokela, J.; Poutanen, M.

2009-09-01

The GPS based deformation studies have been made at the investigation areas of Posiva since 1995, when the network of ten GPS pillars was established at Olkiluoto. The network of seven GPS pillars was built at Kivetty and Romuvaara during the year 1996. One pillar in each investigation area belongs to the Finnish permanent GPS network, FinnRef. A total of 26 GPS measurement campaigns have been carried out at Olkiluoto since 1995, and 17 campaigns at Kivetty and Romuvaara. According to the time series of the GPS results 1/3 of the baselines at Olkiluoto have statistically significant change rates. However, the observed movements are smaller than 0.20 mm/a. The networks of Kivetty and Romuvaara are quite stable expect one pillar at Romuvaara. There are seven pillars, which have statistically significant horizontal velocities at Olkiluoto. These local velocity components are small but taking into account the standard deviations the largest velocity components seems to be reliably determined. The uniform scale for the GPS measurements made in different years is the basic condition for reliable results in the deformation analyses. At Olkiluoto a baseline for electronic distance measurements (EDM) was built in 2002. The baseline has been measured using EDM instruments in connection to the GPS observations. The comparison between the GPS and EDM results can help to fix a possible scale error of the GPS measurements. The GPS network at Olkiluoto was extended in 2003. The new pillars were built close to Kuivalahti village and on a small island of Iso Pyrekari. According to the geological evidence it is expected that a fracture zone is located between the new stations, thus enabling the determination of possible deformations along the fracture zone. The new pillars have been observed since 2003 and now we have computed the first deformation analysis from the six years data. The local crustal deformations have been studied in GeoSatakunta project, too. This GPS network is

GPS operations at Olkiluoto, Kivetty and Romuvaara in 2007

International Nuclear Information System (INIS)

Ahola, J.; Koivula, H.; Jokela, J.

2008-05-01

The GPS based deformation studies have been made at the investigation areas of Posiva since 1995, when the network of ten GPS pillars was established at Olkiluoto. The network of seven GPS pillars was built at Kivetty and Romuvaara during the year 1996. One pillar in each investigation area belongs to the Finnish permanent GPS network, FinnRef. 24 GPS measurement campaigns have been carried out at Olkiluoto since 1995, and 16 campaigns at Kivetty and Romuvaara. According to the time series of the GPS results 1/3 of the baselines at Olkiluoto have statistically significant change rates. However, the observed movements are smaller than ± 0.20 mm/a. The networks of Kivetty and Romuvaara are quite stabile expect one pillar at Romuvaara. There are five pillars, which have statistically significant horizontal velocities at Olkiluoto. These local velocity components are small but taking into account the standard deviations the largest velocity components seems to be reliably determined (maximum velocity is -0.22 mm/a ± 0.02 mm/a). The uniform scale for the GPS measurements made in different years is the basic condition for reliable results in the deformation analyses. At Olkiluoto a baseline for electronic distance measurements (EDM) was built in 2002. The baseline has been measured using EDM instruments simultaneously with the GPS observations. The comparison between the GPS and EDM results can solve a possible scale error of the GPS. The GPS network at Olkiluoto was extended in 2003. The new pillars were built close to Kuivalahti village and on a small island of Iso Pyrekari. According to the geological evidence it is expected that a fracture zone is located between the new stations, thus enabling the determination of possible deformations along the fracture zone. The new pillars have been observed since 2003, but the time series are still too short for reliable deformation studies. The local crustal deformations have been studied in GeoSatakunta project, too. This

GPS operations at Olkiluoto, Kivetty and Romuvaara in 2006

International Nuclear Information System (INIS)

Ahola, J.; Koivula, H.; Poutanen, M.; Jokela, J.

2007-05-01

The GPS based deformation studies have been made at the investigation areas of Posiva since 1995, when the network of ten GPS pillars was established at Olkiluoto. The network of seven GPS pillars was built at Kivetty and Romuvaara during the year 1996. One pillar in each investigation area belongs to the Finnish permanent GPS network, FinnRef. 22 GPS measurement campaigns have been carried out at Olkiluoto since 1995, and 15 campaigns at Kivetty and Romuvaara. According to the time series of the GPS results 1/3 of the baselines at Olkiluoto have statistically significant change rates. However, the observed movements are smaller than ± 0.22 mm/a. The networks of Kivetty and Romuvaara are quite stabile expect one pillar at Romuvaara. There are five pillars, which have statistically significant horizontal velocities at Olkiluoto. These local velocity components are small but taking into account the standard deviations the largest velocity components seems to be reliably determined (maximum velocity is -0.23 mm/a ± 0.023 mm/a). The uniform scale for the GPS measurements made in different years is the basic condition for reliable results in the deformation analyses. At Olkiluoto a baseline for electronic distance measurements (EDM) was built in 2002. The baseline has been measured using EDM instruments simultaneously with the GPS observations. The comparison between the GPS and EDM results can solve a possible scale error of the GPS. The GPS network at Olkiluoto was extended in 2003. The new pillars were built close to Kuivalahti village and on a small island of Iso Pyrekari. According to the geological evidence it is expected that a fracture zone is located between the new stations, thus enabling the determination of possible deformations along the fracture zone. The new pillars have been observed since 2003, but the time series are still too short for reliable deformation studies. The local crustal deformations have been studied in GeoSatakunta project, too. This

Precise levelling campaigns at Olkiluoto in 2006 - 2007

International Nuclear Information System (INIS)

Lehmuskoski, P.

2008-04-01

The GPS observation network of Olkiluoto was constructed in 1994 for monitoring crustal deformations in the investigation area. To fulfil a better vertical control of the GPS network, precise levellings were started in the area in autumn 2003. The GPS network was first connected at Lapijoki to the precise levelling network of Finland to control the vertical movements of the whole island of Olkiluoto. Then the GPS network was levelled. It consisted of the reserve marks of eight GPS pillars and five levelling bench marks, two of which constituted the nodal bench mark pair. The second precise levelling campaign on the area was carried out in autumn 2005. Now only the GPS network added with the antenna platforms of nine GPS pillars were levelled. Compared to the other points, the elevation difference of two reserve mark pairs had changed significantly during two years, about one millimetre. The reason may be the blasting of the rock in the neighbourhood of these points and deformation of the rock after the blasting. Inspired by the observed elevation changes in 2005, micro loops were established and levelled onto the ONKALO and the VLJ Repository in autumn 2006. The micro loops consisted of seven and five bench marks the mean interval being about 300 metres. The campaign in autumn 2007 consisted of the levellings of all measured and undestroyed points of the earlier campaigns. The most interesting results were: (1) Compared to the mean theoretical land uplift the nodal bench mark 03216 near the crossing of Olkiluodontie and Satamatie had risen in four years 2.6 mm more than the nodal bench mark of Lapijoki and 1.9 mm of this occurred within the 0.8 mm long interval which separates the island and the continent. (2) During four years the northern part of the island had risen about one millimetre more than the middle part, where the before mentioned 03216 is located. (3) The elevation differences between the bench marks of the ONKALO micro loop were changed even one

Tectonic Model of Bali Island Inferred from GPS Data

OpenAIRE

Cecep Sulaeman; Sri Hidayati; Amalfi Omang; Imam Catur Priambodo

2018-01-01

DOI: 10.17014/ijog.5.1.81-91Seven periods of GPS campaign have been conducted for three years since March 2013 - October 2015 on fourteen GPS sites across Bali Island. The GAMIT/GLOBK 10.6 version was used to compute data with respect for thirteen reference sites of International Terrestrial Reference Frame (ITRF) 2008 surrounding Bali. The result shows that horizontal displacement varies between 1.93 and 22.53 mm/yr dominantly northeastward. Vertical displacement ranges at -184.34 to 33.79 m...

Performance Enhancement of Land Vehicle Positioning Using Multiple GPS Receivers in an Urban Area

Directory of Open Access Journals (Sweden)

Jong-Hwa Song

2016-10-01

Full Text Available The Global Positioning System (GPS is the most widely used navigation system in land vehicle applications. In urban areas, the GPS suffers from insufficient signal strength, multipath propagation and non-line-of-sight (NLOS errors, so it thus becomes difficult to obtain accurate and reliable position information. In this paper, an integration algorithm for multiple receivers is proposed to enhance the positioning performance of GPS for land vehicles in urban areas. The pseudoranges of multiple receivers are integrated based on a tightly coupled approach, and erroneous measurements are detected by testing the closeness of the pseudoranges. In order to fairly compare the pseudoranges, GPS errors and terms arising due to the differences between the positions of the receivers need to be compensated. The double-difference technique is used to eliminate GPS errors in the pseudoranges, and the geometrical distance is corrected by projecting the baseline vector between pairs of receivers. In order to test and analyze the proposed algorithm, an experiment involving live data was performed. The positioning performance of the algorithm was compared with that of the receiver autonomous integrity monitoring (RAIM-based integration algorithm for multiple receivers. The test results showed that the proposed algorithm yields more accurate position information in urban areas.

FY17 NIF Performance Quad Campaign: laser performance results and conclusions

Energy Technology Data Exchange (ETDEWEB)

Di Nicola, J. M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Mennerat, G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Widmayer, G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2017-10-09

The FY17 NIF Performance Quad Campaign exercised a single quad of NIF (Q45T) at elevated energy to assess the impact of recent improvements to the infrared (1ω) and ultraviolet (3ω) section of the laser on integrated performance.

Performance Enhancement of Land Vehicle Positioning Using Multiple GPS Receivers in an Urban Area

OpenAIRE

Song, Jong-Hwa; Jee, Gyu-In

2016-01-01

The Global Positioning System (GPS) is the most widely used navigation system in land vehicle applications. In urban areas, the GPS suffers from insufficient signal strength, multipath propagation and non-line-of-sight (NLOS) errors, so it thus becomes difficult to obtain accurate and reliable position information. In this paper, an integration algorithm for multiple receivers is proposed to enhance the positioning performance of GPS for land vehicles in urban areas. The pseudoranges of multi...

Re-investigation of slip rate along the southern part of the Sumatran Fault Zone using SuMo GPS network

Science.gov (United States)

Hermawan, I.; Lubis, A. M.; Sahputra, R.; Hill, E.; Sieh, K.; Feng, L.; Salman, R.; Hananto, N.

2015-12-01

The Sumatran Fault Zone (SFZ) accommodates a significant component of the strike-slip motion of oblique convergence along the Sumatra subduction zone. Previous studies have suggested that the slip rates of the SFZ increase from south to north. However, recent work shows that the slip rates may not vary along the SFZ [Bradley et al., 2015]. New data are needed to help confirm these results, and to assess slip-rate variability and fault segmentation in more detail. This information is vital for seismic hazard assessment for the region. We have therefore installed and operated the SuMo (Sumatran Fault Monitoring) network, a dense GPS campaign network focused around the SFZ. From 2013-2015 we selected and installed 32 GPS monuments over the southern part of the SFZ. The network comprises of three transects. The first transect is around the location of the great 1900 earthquake, at the Musi segment. Two transects cover the Manna segment, which saw its last great earthquake in 1893, and the Kumering segment, which saw two great earthquakes in 1933 (M 7.5) and 1994 (M 7.0). We have now conducted three GPS campaign surveys for these stations (3-4 days of measurement for each occupation site), and established 5 semi-permanent cGPS stations in the area. The processed data show that the campaigns sites are still too premature to be used for estimating slip rates, but from the preliminary results for the semi-permanent stations we may see our first signal of deformation. More data from future survey campaigns will help us to estimated revised slip rates. In addition to the science goals for our project, we are this year starting a project called "SuMo Goes to School," which will aim to disseminate information on our science to the schools that house the SuMo GPS stations. The SuMo project also achieves capacity building by training students from Bengkulu University in geodesy and campaign GPS survey techniques.

Performance Evaluation of Block Acquisition and Tracking Algorithms Using an Open Source GPS Receiver Platform

Science.gov (United States)

Ramachandran, Ganesh K.; Akopian, David; Heckler, Gregory W.; Winternitz, Luke B.

2011-01-01

Location technologies have many applications in wireless communications, military and space missions, etc. US Global Positioning System (GPS) and other existing and emerging Global Navigation Satellite Systems (GNSS) are expected to provide accurate location information to enable such applications. While GNSS systems perform very well in strong signal conditions, their operation in many urban, indoor, and space applications is not robust or even impossible due to weak signals and strong distortions. The search for less costly, faster and more sensitive receivers is still in progress. As the research community addresses more and more complicated phenomena there exists a demand on flexible multimode reference receivers, associated SDKs, and development platforms which may accelerate and facilitate the research. One of such concepts is the software GPS/GNSS receiver (GPS SDR) which permits a facilitated access to algorithmic libraries and a possibility to integrate more advanced algorithms without hardware and essential software updates. The GNU-SDR and GPS-SDR open source receiver platforms are such popular examples. This paper evaluates the performance of recently proposed block-corelator techniques for acquisition and tracking of GPS signals using open source GPS-SDR platform.

Purex process operation and performance, 1970 Thoria Campaign

International Nuclear Information System (INIS)

Jackson, R.R.; Walser, R.L.

1977-03-01

The Hanford Purex Plant fulfilled a 1970 commitment to the Atomic Energy Commission to produce 360 kilograms of high purity 233 U as uranyl nitrate solution. Overall plant performance during both 1970 and 1966 confirmed the suitability of Purex for processing thorium on a campaign basis. The 1970 processing campaign, including flushing operations, is discussed with particular emphasis on problem areas. Background information on the process and equipment used is also presented. The organizations and their designations described are those existing in 1970

Assessing the Performance of GPS Precise Point Positioning Under Different Geomagnetic Storm Conditions during Solar Cycle 24

Directory of Open Access Journals (Sweden)

Xiaomin Luo

2018-06-01

Full Text Available The geomagnetic storm, which is an abnormal space weather phenomenon, can sometimes severely affect GPS signal propagation, thereby impacting the performance of GPS precise point positioning (PPP. However, the investigation of GPS PPP accuracy over the global scale under different geomagnetic storm conditions is very limited. This paper for the first time presents the performance of GPS dual-frequency (DF and single-frequency (SF PPP under moderate, intense, and super storms conditions during solar cycle 24 using a large data set collected from about 500 international GNSS services (IGS stations. The global root mean square (RMS maps of GPS PPP results show that stations with degraded performance are mainly distributed at high-latitude, and the degradation level generally depends on the storm intensity. The three-dimensional (3D RMS of GPS DF PPP for high-latitude during moderate, intense, and super storms are 0.393 m, 0.680 m and 1.051 m, respectively, with respect to only 0.163 m on quiet day. RMS errors of mid- and low-latitudes show less dependence on the storm intensities, with values less than 0.320 m, compared to 0.153 m on quiet day. Compared with DF PPP, the performance of GPS SF PPP is inferior regardless of quiet or disturbed conditions. The degraded performance of GPS positioning during geomagnetic storms is attributed to the increased ionospheric disturbances, which have been confirmed by our global rate of TEC index (ROTI maps. Ionospheric disturbances not only lead to the deteriorated ionospheric correction but also to the frequent cycle-slip occurrence. Statistical results show that, compared with that on quiet day, the increased cycle-slip occurrence are 13.04%, 56.52%, and 69.57% under moderate, intense, and super storms conditions, respectively.

Error and Performance Analysis of MEMS-based Inertial Sensors with a Low-cost GPS Receiver

Directory of Open Access Journals (Sweden)

Yang Gao

2008-03-01

Full Text Available Global Navigation Satellite Systems (GNSS, such as the Global Positioning System (GPS, have been widely utilized and their applications are becoming popular, not only in military or commercial applications, but also for everyday life. Although GPS measurements are the essential information for currently developed land vehicle navigation systems (LVNS, GPS signals are often unavailable or unreliable due to signal blockages under certain environments such as urban canyons. This situation must be compensated in order to provide continuous navigation solutions. To overcome the problems of unavailability and unreliability using GPS and to be cost and size effective as well, Micro Electro Mechanical Systems (MEMS based inertial sensor technology has been pushing for the development of low-cost integrated navigation systems for land vehicle navigation and guidance applications. This paper will analyze the characterization of MEMS based inertial sensors and the performance of an integrated system prototype of MEMS based inertial sensors, a low-cost GPS receiver and a digital compass. The influence of the stochastic variation of sensors will be assessed and modeled by two different methods, namely Gauss-Markov (GM and AutoRegressive (AR models, with GPS signal blockage of different lengths. Numerical results from kinematic testing have been used to assess the performance of different modeling schemes.

GPS measurements along the North Anatolian fault zone ont he Mid-Anatolia segment

Science.gov (United States)

Yavasoglu, H.; Team

2003-04-01

The North Anatolian Fault (NAF) is the most important tectonic feature in Turkey producing lots of earthquakes that cause deaths, wounds and loss of property in large scale. So, there are a lot of seismic, geodetic, geologic and geophysical researches through NAF. A new project, "Determination of Kinematics along the North Anatolian Fault Branch between Ladik and Ilgaz with GPS Measurements", founded by The Scientific and Technical Research Council of Turkey (TUBITAK) and Istanbul Technical University (ITU) Research Fund is also started. The aim of the project is to determine the magnitude and direction of the block movements in the region by using GPS. Having the knowledge about the neotectonics of the region with the contributions of geology and seismology after the GPS campaigns will provide further information on the assessment of the earthquake potential. In this work, the planning stage of the network is examined. Also pre-results from the first and second surveying campaigns are presented. 1. INTRODUCTION The tectonic framework of the Eastern Mediterranean is dominated by the collision of the Arabian and African plates with the Eurasia. This collision created wide variety of tectonic processes such as folds and thrust belts, major continental strike-slip faults, opening of pull-apart basins etc. All these tectonic caused long-term destructive earthquakes in Anatolia Last earthquakes occurred at the end of the 20th Century, in 17th of August and 12 of November 1999, Golcuk and Duzce earthquakes, also focused the attention of international science community over the tectonics and kinematics of the NAF. A westward migrating earthquakes series starting from 1939 Erzincan earthquake, produced more than 1000 kilometers of ruptures between Erzincan and Sea of Marmara 2. GEOLOGICAL FEATURES OF NAF The North Anatolian Fault (NAF) is one of the longest active strike slip systems. Slip rate of the NAF was estimated from the GPS data as 24±1mm/yr. One of the important

An analysis of the Aespoe crustal motion-monitoring network observed by GPS in 2000, 2001 and 2002

International Nuclear Information System (INIS)

Sjoeberg, Lars E.; Ming Pan; Asenjo, Erick

2002-07-01

A feasibility study of using GPS technology for monitoring possible crustal 'creep' motions as part of the long-term site investigations for the decision on site location of nuclear waste disposal has been carried out in an established test network near Oskarshamn in the south east of Sweden. The network, consisting of 7 points, is located in an approximate area of 15 x 15 km, and two possibly active faults in the crust cross the area. The points are realized by steel pegs, installed and cemented into boreholes in the bedrock, and the GPS antennas are mounted directly on top of the steel pegs by so-called forced centring, i.e. repeatedly without any centring bias. The GPS data were measured 3 times per year, or in total at 6 epochs, between June 2000 and February 2002. At each epoch GPS receivers occupied all 7 sites for at least 48 hours of measurement. In addition, data from the nearest SWEPOS GPS station at Oskarshamn was used as a reference for the analysis. In general the observations performed well without many problems. The Bernese GPS software version 4.2 was used to adjust the data. First, the adjustment was performed epoch by epoch to determine site coordinates and baseline lengths. The achieved coordinate standard error is of the order of 1 mm. The baseline evolutions were found to be less than 1 mm/yr, except for the long baseline to the SWEPOS station, which reached 2 mm/yr. However, as the corresponding standard errors are of the order of 0.5 and 1 mm/yr, respectively, the estimated baseline velocities are not significant, but the hypothesis of zero-velocities holds. Further data from future GPS campaigns may change or confirm this conclusion. Second, the GPS software was used to merge the epoch-wise results into final site coordinates and their temporal variations. A special theoretical investigation by linear regression was carried out to estimate a scale factor of the formal standard errors of coordinates and their temporal changes provided by the

The Performance Analysis of a Real-Time Integrated INS/GPS Vehicle Navigation System with Abnormal GPS Measurement Elimination

Directory of Open Access Journals (Sweden)

Jhen-Kai Liao

2013-08-01

Full Text Available The integration of an Inertial Navigation System (INS and the Global Positioning System (GPS is common in mobile mapping and navigation applications to seamlessly determine the position, velocity, and orientation of the mobile platform. In most INS/GPS integrated architectures, the GPS is considered to be an accurate reference with which to correct for the systematic errors of the inertial sensors, which are composed of biases, scale factors and drift. However, the GPS receiver may produce abnormal pseudo-range errors mainly caused by ionospheric delay, tropospheric delay and the multipath effect. These errors degrade the overall position accuracy of an integrated system that uses conventional INS/GPS integration strategies such as loosely coupled (LC and tightly coupled (TC schemes. Conventional tightly coupled INS/GPS integration schemes apply the Klobuchar model and the Hopfield model to reduce pseudo-range delays caused by ionospheric delay and tropospheric delay, respectively, but do not address the multipath problem. However, the multipath effect (from reflected GPS signals affects the position error far more significantly in a consumer-grade GPS receiver than in an expensive, geodetic-grade GPS receiver. To avoid this problem, a new integrated INS/GPS architecture is proposed. The proposed method is described and applied in a real-time integrated system with two integration strategies, namely, loosely coupled and tightly coupled schemes, respectively. To verify the effectiveness of the proposed method, field tests with various scenarios are conducted and the results are compared with a reliable reference system.

USGS Menlo Park GPS Data Processing Techniques and Derived North America Velocity Field (Invited)

Science.gov (United States)

Svarc, J. L.; Murray-Moraleda, J. R.; Langbein, J. O.

2010-12-01

The U.S. Geological Survey in Menlo Park routinely conducts repeated GPS surveys of geodetic markers throughout the western United States using dual-frequency geodetic GPS receivers. We combine campaign, continuous, and semi-permanent data to present a North America fixed velocity field for regions in the western United States. Mobile campaign-based surveys require less up-front investment than permanently monumented and telemetered GPS systems, and hence have achieved a broad and dense spatial coverage. The greater flexibility and mobility comes at the cost of greater uncertainties in individual daily position solutions. We also routinely process continuous GPS data collected at PBO stations operated by UNAVCO along with data from other continuous GPS networks such as BARD, PANGA, and CORS operated by other agencies. We have broken the Western US into several subnetworks containing approximately 150-250 stations each. The data are processed using JPL’s GIPSY-OASIS II release 5.0 software using a modified precise positioning strategy (Zumberge and others, 1997). We use the “ambizap” code provided by Geoff Blewitt (Blewitt, 2008) to fix phase ambiguities in continuous networks. To mitigate the effect of common mode noise we use the positions of stations in the network with very long, clean time series (i.e. those with no large outliers or offsets) to transform all position estimates into “regionally filtered” results following the approach of Hammond and Thatcher (2007). Velocity uncertainties from continuously operated GPS stations tend to be about 3 times smaller than those from campaign data. Langbein (2004) presents a maximum likelihood method for fitting a time series employing a variety of temporal noise models. We assume that GPS observations are contaminated by a combination of white, flicker, and random walk noise. For continuous and semi-permanent time series longer than 2 years we estimate these values, otherwise we fix the amplitudes of these

Toward 10(exp 9) GPS geodesy: Vector baselines, Earth rotation and reference frames

Science.gov (United States)

Schutz, Bob E.

1993-01-01

The University of Texas Center for Space Research research efforts under NASA Grant No. NAG-1936 from 1 Jan. 1992 - 31 Dec. 1992 were in the following areas: GPS orbit accuracy assessments and efforts to improve the accuracy; analysis of global GPS data collected during the first three months of the IGS campaign, and analysis of regional data. A brief summary of each of the above activities is presented in the following.

GPS Space Service Volume: Ensuring Consistent Utility Across GPS Design Builds for Space Users

Science.gov (United States)

Bauer, Frank H.; Parker, Joel Jefferson Konkl; Valdez, Jennifer Ellen

2015-01-01

GPS availability and signal strength originally specified for users on or near surface of Earth with transmitted power levels specified at edge-of-Earth, 14.3 degrees. Prior to the SSV specification, on-orbit performance of GPS varied from block build to block build (IIA, IIRM, IIF) due to antenna gain and beam width variances. Unstable on-orbit performance results in significant risk to space users. Side-lobe signals, although not specified, were expected to significantly boost GPS signal availability for users above the constellation. During GPS III Phase A, NASA noted significant discrepancies in power levels specified in GPS III specification documents, and measured on-orbit performance. To stabilize the signal for high altitude space users, NASA DoD team in 2003-2005 led the creation of new Space Service Volume (SSV) definition and specifications.

Operational aspects of CASA UNO '88-The first large scale international GPS geodetic network

Science.gov (United States)

Neilan, Ruth E.; Dixon, T. H.; Meehan, Thomas K.; Melbourne, William G.; Scheid, John A.; Kellogg, J. N.; Stowell, J. L.

1989-01-01

For three weeks, from January 18 to February 5, 1988, scientists and engineers from 13 countries and 30 international agencies and institutions cooperated in the most extensive GPS (Global Positioning System) field campaign, and the largest geodynamics experiment, in the world to date. This collaborative eperiment concentrated GPS receivers in Central and South America. The predicted rates of motions are on the order of 5-10 cm/yr. Global coverage of GPS observations spanned 220 deg of longitude and 125 deg of latitude using a total of 43 GPS receivers. The experiment was the first civilian effort at implementing an extended international GPS satellite tracking network. Covariance analyses incorporating the extended tracking network predicted significant improvement in precise orbit determination, allowing accurate long-baseline geodesy in the science areas.

Comparison of GPS and GRACE hydrological loading signatures in Myanmar, India, Bangladesh, and Bhutan

Science.gov (United States)

Materna, K.; Feng, L.; Lindsey, E. O.; Hill, E.; Burgmann, R.

2017-12-01

The elastic response of the lithosphere to surface mass redistributions produces significant deformation that can be observed in geodetic time series. This deformation is especially pronounced in Southeast Asia, where the annual monsoon produces large-amplitude hydrological loads. The MIBB network of 20 continuous GPS stations in Myanmar, India, Bangladesh, and Bhutan, operational since 2012, provides an opportunity to study the earth's response to these loads. In this study, we use GRACE gravity products as an estimate of surface water distribution, and input these estimates into an elastic loading calculation. We compare the predicted deformation with that observed with GPS. We find that elastic loading from the GRACE gravity field is able to explain the phase and the peak-to-peak amplitude (typically 2-3 cm) of the vertical GPS oscillations in northeast India and central Myanmar. GRACE-based corrections reduce the RMS scatter of the GPS data by 30%-45% in these regions. However, this approach does not capture all of the variation in central Bangladesh and southern Myanmar. Local hydrological effects, non-tidal ocean loads, poroelastic deformation, or differences in elastic properties may explain discrepancies between the GPS and GRACE signals in these places. The results of our calculations have practical implications for campaign GPS measurements in Myanmar, which make up the majority of geodetic measurements at this point. We may be able to reduce errors in campaign measurements and increase the accuracy of velocity estimates by correcting for hydrologic signals with GRACE data. The results also have potential implications for crustal rheology in Southeast Asia.

Bridge Performance Assessment Based on an Adaptive Neuro-Fuzzy Inference System with Wavelet Filter for the GPS Measurements

Directory of Open Access Journals (Sweden)

Mosbeh R. Kaloop

2015-10-01

Full Text Available This study describes the performance assessment of the Huangpu Bridge in Guangzhou, China based on long-term monitoring in real-time by the kinematic global positioning system (RTK-GPS technique. Wavelet transformde-noising is applied to filter the GPS measurements, while the adaptive neuro-fuzzy inference system (ANFIS time series output-only model is used to predict the deformations of GPS-bridge monitoring points. In addition, GPS and accelerometer monitoring systems are used to evaluate the bridge oscillation performance. The conclusions drawn from investigating the numerical results show that: (1the wavelet de-noising of the GPS measurements of the different recording points on the bridge is a suitable tool to efficiently eliminate the signal noise and extract the different deformation components such as: semi-static and dynamic displacements; (2 the ANFIS method with two multi-input single output model is revealed to powerfully predict GPS movement measurements and assess the bridge deformations; and (3 The installed structural health monitoring system and the applied ANFIS movement prediction performance model are solely sufficient to assure bridge safety based on the analyses of the different filtered movement components.

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.

'Start the conversation': the New South Wales (Australia) family health history campaign.

Science.gov (United States)

Dunlop, K; Barlow-Stewart, K

2010-01-01

Evidence that family health history (FHH) informs recommendations for appropriate early detection strategies used for the prevention of many health conditions underscores the importance of optimizing a patient's knowledge of his/her personal FHH. For some conditions, FHH also underpins identifying those at potentially high risk for whom genetic testing may be possible and suitable to further inform the advice. The Family Health History Campaign 'Start the Conversation' was conducted in New South Wales (Australia) in August 2006 as a small state-wide media campaign with the aim of encouraging individuals to discuss and gather their FHH information about several conditions and report it to their doctor. Campaign development included consultations with consumers and primary care practitioners (general practitioners - GPs), development of campaign resources, and establishment of partnerships. Evaluation methodologies included community poll surveys pre- and post-campaign, a GP mail survey, and website usage analysis. While only 112/403 of the polled community reported hearing about the campaign in the media, 48% of those men and women were encouraged to start the conversation with their families. Limited findings from the GP survey respondents suggested they were engaged, made aware of the potential lack of patient knowledge about FHH and generated referral for several high-risk patients. Campaigns that use the media to encourage the community to take action and also engage the GPs can create a supportive environment that has the potential to increase the accuracy with reporting of FHH to maximize benefit for early detection and prevention.

Upgradation of MOT and its Relevance to WET Campaigns Alisher S ...

Indian Academy of Sciences (India)

instrumentation of the telescope and how the system can be used in future campaigns. .... After the upgrade, the MOT should have computer control of pointing, tracking and focus, with ... For this purpose we plan to use portable GPS station.

GPs' perceptions of advance care planning with frail and older people: a qualitative study.

Science.gov (United States)

Sharp, Tim; Malyon, Alexandra; Barclay, Stephen

2018-01-01

Frail and older people are estimated to account for 40% of deaths. Despite conversations about end-of-life care being an important component of the national End of Life Care Strategy, there is a marked disparity between the majority who would like to discuss advance care plans, and the minority who currently have this opportunity. To investigate the attitudes of GPs to advance care planning (ACP) discussions with frail and older individuals. Focus group study with GPs in Cambridgeshire between September 2015 and January 2016. Five focus groups with 21 GPs were purposively sampled to maximise diversity. Framework analysis was used to analyse transcripts and develop themes. Although some GPs were concerned it might cause distress, the majority felt that raising ACP was important, especially as preparation for future emergencies. Knowing the individuals, introducing the idea as part of ongoing discussions, and public awareness campaigns were all facilitators identified. Several considered that service limitations made it difficult to fulfil patients' wishes and risked raising unrealistic patient expectations. Other barriers identified included uncertainty over prognosis and difficulties ensuring that individuals' wishes were respected. Most GPs viewed ACP as important. However, their enthusiasm was tempered by experience. This study highlights the difficulties for GPs of encouraging dialogue and respecting individuals' wishes within the constraints of the existing health and social care system. National publicity campaigns and encouraging patients to prioritise healthcare outcomes could help GPs raise care preferences without causing a detrimental impact on patients or raising unrealistic expectations. Once patients agree their care preferences, they need to be documented, accessible, and reviewed by all relevant health and social care providers to ensure that their wishes are respected, and plans amended as their circumstances change. © British Journal of General

Profile of English salaried GPs: labour mobility and practice performance.

Science.gov (United States)

Ding, Alexander; Hann, Mark; Sibbald, Bonnie

2008-01-01

Recent national policy changes have provided greater flexibility in GPs' contracts. One such policy is salaried employment, which offers reduced hours and freedom from out-of-hours and administrative responsibilities, aimed at improving recruitment and retention in a labour market facing regional shortages. To profile salaried GPs and assess their mobility within the labour market. Serial cross-sectional study. All GPs practising in England during the years 1996/1997, 2000/2001, and 2004/2005. Descriptive analyses, logistic regression. Salaried GPs tended to be either younger ( or =65 years), female, or overseas-qualified; they favoured part-time working and personal medical services contracts. Salaried GPs were more mobile than GP principals, and have become increasingly so, despite a trend towards reduced overall mobility in the GP workforce. Practices with salaried GPs scored more Quality and Outcomes Framework points and were located in slightly more affluent areas. Salaried status appears to have reduced limitations in the labour market, leading to better workforce deployment from a GP's perspective. However, there is no evidence to suggest it has relieved inequalities in GP distribution.

Central and South America GPS geodesy - CASA Uno

Science.gov (United States)

Kellogg, James N.; Dixon, Timothy H.

1990-01-01

In January 1988, scientists from over 25 organizations in 13 countries and territories cooperated in the largest GPS campaign in the world to date. A total of 43 GPS receivers collected approximately 590 station-days of data in American Samoa, Australia, Canada, Colombia, Costa Rica, Ecuador, New Zealand, Norway, Panama, Sweden, United States, West Germany, and Venezuela. The experiment was entitled CASA Uno. Scientific goals of the project include measurements of strain in the northern Andes, subduction rates for the Cocos and Nazca plates beneath Central and South America, and relative motion between the Caribbean plate and South America. A second set of measurements are planned in 1991 and should provide preliminary estimates of crustal deformation and plate motion rates in the region.

Empirical Analysis and Characterization of Indoor GPS Signal Fading and Multipath Conditions

DEFF Research Database (Denmark)

Blunck, Henrik; Kjærgaard, Mikkel Baun; Godsk, Torben

2009-01-01

of earlier measurement campaigns to characterize GNSS signal conditions in indoor environments have been published prominently in the GNSS research literature, see, e.g. [1,2,3]. To allow for in-depth signal analysis, these campaigns use a variety of measuring machinery such as channel sounders, mobile...... signal generators and spectrum analyzers. Furthermore, the use-case-specific usability of GPS as an indoor positioning technology as been evaluated empirically on a higher level, see, e.g. [4]. In this paper we present results of a measurement campaign, designed to characterize indoor GNSS signal...... conditions. The work presented can therefore be seen as an effort to the campaigns mentioned above. As the focus of our work lies on the real-world usability of current GNSS technology for indoor use, we employ in our measurement campaign foremost commercial receivers with features, typical for the use cases...

A Low-Cost GPS GSM/GPRS Telemetry System: Performance in Stationary Field Tests and Preliminary Data on Wild Otters (Lutra lutra)

Science.gov (United States)

Quaglietta, Lorenzo; Martins, Bruno Herlander; de Jongh, Addy; Mira, António; Boitani, Luigi

2012-01-01

Background Despite the increasing worldwide use of global positioning system (GPS) telemetry in wildlife research, it has never been tested on any freshwater diving animal or in the peculiar conditions of the riparian habitat, despite this latter being one of the most important habitat types for many animal taxa. Moreover, in most cases, the GPS devices used have been commercial and expensive, limiting their use in low-budget projects. Methodology/Principal Findings We have developed a low-cost, easily constructed GPS GSM/GPRS (Global System for Mobile Communications/General Packet Radio Service) and examined its performance in stationary tests, by assessing the influence of different habitat types, including the riparian, as well as water submersion and certain climatic and environmental variables on GPS fix-success rate and accuracy. We then tested the GPS on wild diving animals, applying it, for the first time, to an otter species (Lutra lutra). The rate of locations acquired during the stationary tests reached 63.2%, with an average location error of 8.94 m (SD = 8.55). GPS performance in riparian habitats was principally affected by water submersion and secondarily by GPS inclination and position within the riverbed. Temporal and spatial correlations of location estimates accounted for some variation in the data sets. GPS-tagged otters also provided accurate locations and an even higher GPS fix-success rate (68.2%). Conclusions/Significance Our results suggest that GPS telemetry is reliably applicable to riparian and even diving freshwater animals. They also highlight the need, in GPS wildlife studies, for performing site-specific pilot studies on GPS functioning as well as for taking into account eventual spatial and temporal correlation of location estimates. The limited price, small dimensions, and high performance of the device presented here make it a useful and cost-effective tool for studies on otters and other aquatic or terrestrial medium

A low-cost GPS GSM/GPRS telemetry system: performance in stationary field tests and preliminary data on wild otters (Lutra lutra.

Directory of Open Access Journals (Sweden)

Lorenzo Quaglietta

Full Text Available BACKGROUND: Despite the increasing worldwide use of global positioning system (GPS telemetry in wildlife research, it has never been tested on any freshwater diving animal or in the peculiar conditions of the riparian habitat, despite this latter being one of the most important habitat types for many animal taxa. Moreover, in most cases, the GPS devices used have been commercial and expensive, limiting their use in low-budget projects. METHODOLOGY/PRINCIPAL FINDINGS: We have developed a low-cost, easily constructed GPS GSM/GPRS (Global System for Mobile Communications/General Packet Radio Service and examined its performance in stationary tests, by assessing the influence of different habitat types, including the riparian, as well as water submersion and certain climatic and environmental variables on GPS fix-success rate and accuracy. We then tested the GPS on wild diving animals, applying it, for the first time, to an otter species (Lutra lutra. The rate of locations acquired during the stationary tests reached 63.2%, with an average location error of 8.94 m (SD = 8.55. GPS performance in riparian habitats was principally affected by water submersion and secondarily by GPS inclination and position within the riverbed. Temporal and spatial correlations of location estimates accounted for some variation in the data sets. GPS-tagged otters also provided accurate locations and an even higher GPS fix-success rate (68.2%. CONCLUSIONS/SIGNIFICANCE: Our results suggest that GPS telemetry is reliably applicable to riparian and even diving freshwater animals. They also highlight the need, in GPS wildlife studies, for performing site-specific pilot studies on GPS functioning as well as for taking into account eventual spatial and temporal correlation of location estimates. The limited price, small dimensions, and high performance of the device presented here make it a useful and cost-effective tool for studies on otters and other aquatic or

A Performance Improvement Method for Low-Cost Land Vehicle GPS/MEMS-INS Attitude Determination

Directory of Open Access Journals (Sweden)

Li Cong

2015-03-01

Full Text Available Global positioning system (GPS technology is well suited for attitude determination. However, in land vehicle application, low-cost single frequency GPS receivers which have low measurement quality are often used, and external factors such as multipath and low satellite visibility in the densely built-up urban environment further degrade the quality of the GPS measurements. Due to the low-quality receivers used and the challenging urban environment, the success rate of the single epoch ambiguity resolution for dynamic attitude determination is usually quite low. In this paper, a micro-electro-mechanical system (MEMS—inertial navigation system (INS-aided ambiguity resolution method is proposed to improve the GPS attitude determination performance, which is particularly suitable for land vehicle attitude determination. First, the INS calculated baseline vector is augmented with the GPS carrier phase and code measurements. This improves the ambiguity dilution of precision (ADOP, resulting in better quality of the unconstrained float solution. Second, the undesirable float solutions caused by large measurement errors are further filtered and replaced using the INS-aided ambiguity function method (AFM. The fixed solutions are then obtained by the constrained least squares ambiguity decorrelation (CLAMBDA algorithm. Finally, the GPS/MEMS-INS integration is realized by the use of a Kalman filter. Theoretical analysis of the ADOP is given and experimental results demonstrate that our proposed method can significantly improve the quality of the float ambiguity solution, leading to high success rate and better accuracy of attitude determination.

A Performance Improvement Method for Low-Cost Land Vehicle GPS/MEMS-INS Attitude Determination

Science.gov (United States)

Cong, Li; Li, Ercui; Qin, Honglei; Ling, Keck Voon; Xue, Rui

2015-01-01

Global positioning system (GPS) technology is well suited for attitude determination. However, in land vehicle application, low-cost single frequency GPS receivers which have low measurement quality are often used, and external factors such as multipath and low satellite visibility in the densely built-up urban environment further degrade the quality of the GPS measurements. Due to the low-quality receivers used and the challenging urban environment, the success rate of the single epoch ambiguity resolution for dynamic attitude determination is usually quite low. In this paper, a micro-electro-mechanical system (MEMS)—inertial navigation system (INS)-aided ambiguity resolution method is proposed to improve the GPS attitude determination performance, which is particularly suitable for land vehicle attitude determination. First, the INS calculated baseline vector is augmented with the GPS carrier phase and code measurements. This improves the ambiguity dilution of precision (ADOP), resulting in better quality of the unconstrained float solution. Second, the undesirable float solutions caused by large measurement errors are further filtered and replaced using the INS-aided ambiguity function method (AFM). The fixed solutions are then obtained by the constrained least squares ambiguity decorrelation (CLAMBDA) algorithm. Finally, the GPS/MEMS-INS integration is realized by the use of a Kalman filter. Theoretical analysis of the ADOP is given and experimental results demonstrate that our proposed method can significantly improve the quality of the float ambiguity solution, leading to high success rate and better accuracy of attitude determination. PMID:25760057

3-D Spatial Analysis of Deformation at Ikpoba Dam From GPS Data ...

African Journals Online (AJOL)

In this study, analysis of the measurement data obtained by differential GPS at the Ikpoba River Dam was carried out. The measurement system consisted of 19 control and reference stations. DGPS data were collected during two measurement campaigns carried out in 2008 and 2009 respectively using five dual frequency ...

Capsule Performance Optimization in the National Ignition Campaign

Energy Technology Data Exchange (ETDEWEB)

Landen, O L; MacGowan, B J; Haan, S W; Edwards, J

2009-10-13

A capsule performance optimization campaign will be conducted at the National Ignition Facility to substantially increase the probability of ignition. The campaign will experimentally correct for residual uncertainties in the implosion and hohlraum physics used in our radiation-hydrodynamic computational models before proceeding to cryogenic-layered implosions and ignition attempts. The required tuning techniques using a variety of ignition capsule surrogates have been demonstrated at the Omega facility under scaled hohlraum and capsule conditions relevant to the ignition design and shown to meet the required sensitivity and accuracy. In addition, a roll-up of all expected random and systematic uncertainties in setting the key ignition laser and target parameters due to residual measurement, calibration, cross-coupling, surrogacy, and scale-up errors has been derived that meets the required budget.

Capsule performance optimization in the national ignition campaign

International Nuclear Information System (INIS)

Landen, O L; MacGowan, B J; Haan, S W; Edwards, J

2010-01-01

A capsule performance optimization campaign will be conducted at the National Ignition Facility [1] to substantially increase the probability of ignition. The campaign will experimentally correct for residual uncertainties in the implosion and hohlraum physics used in our radiation-hydrodynamic computational models before proceeding to cryogenic-layered implosions and ignition attempts. The required tuning techniques using a variety of ignition capsule surrogates have been demonstrated at the Omega facility under scaled hohlraum and capsule conditions relevant to the ignition design and shown to meet the required sensitivity and accuracy. In addition, a roll-up of all expected random and systematic uncertainties in setting the key ignition laser and target parameters due to residual measurement, calibration, cross-coupling, surrogacy, and scale-up errors has been derived that meets the required budget.

Capsule performance optimization in the national ignition campaign

Science.gov (United States)

Landen, O. L.; MacGowan, B. J.; Haan, S. W.; Edwards, J.

2010-08-01

A capsule performance optimization campaign will be conducted at the National Ignition Facility [1] to substantially increase the probability of ignition. The campaign will experimentally correct for residual uncertainties in the implosion and hohlraum physics used in our radiation-hydrodynamic computational models before proceeding to cryogenic-layered implosions and ignition attempts. The required tuning techniques using a variety of ignition capsule surrogates have been demonstrated at the Omega facility under scaled hohlraum and capsule conditions relevant to the ignition design and shown to meet the required sensitivity and accuracy. In addition, a roll-up of all expected random and systematic uncertainties in setting the key ignition laser and target parameters due to residual measurement, calibration, cross-coupling, surrogacy, and scale-up errors has been derived that meets the required budget.

On the Realistic Stochastic Model of GPS Observables: Implementation and Performance

Science.gov (United States)

Zangeneh-Nejad, F.; Amiri-Simkooei, A. R.; Sharifi, M. A.; Asgari, J.

2015-12-01

High-precision GPS positioning requires a realistic stochastic model of observables. A realistic GPS stochastic model of observables should take into account different variances for different observation types, correlations among different observables, the satellite elevation dependence of observables precision, and the temporal correlation of observables. Least-squares variance component estimation (LS-VCE) is applied to GPS observables using the geometry-based observation model (GBOM). To model the satellite elevation dependent of GPS observables precision, an exponential model depending on the elevation angles of the satellites are also employed. Temporal correlation of the GPS observables is modelled by using a first-order autoregressive noise model. An important step in the high-precision GPS positioning is double difference integer ambiguity resolution (IAR). The fraction or percentage of success among a number of integer ambiguity fixing is called the success rate. A realistic estimation of the GNSS observables covariance matrix plays an important role in the IAR. We consider the ambiguity resolution success rate for two cases, namely a nominal and a realistic stochastic model of the GPS observables using two GPS data sets collected by the Trimble R8 receiver. The results confirm that applying a more realistic stochastic model can significantly improve the IAR success rate on individual frequencies, either on L1 or on L2. An improvement of 20% was achieved to the empirical success rate results. The results also indicate that introducing the realistic stochastic model leads to a larger standard deviation for the baseline components by a factor of about 2.6 on the data sets considered.

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

Science.gov (United States)

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

1994-01-01

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

Near Real-Time Processing and Archiving of GPS Surveys for Crustal Motion Monitoring

Science.gov (United States)

Crowell, B. W.; Bock, Y.

2008-12-01

We present an inverse instantaneous RTK method for rapidly processing and archiving GPS data for crustal motion surveys that gives positional accuracy similar to traditional post-processing methods. We first stream 1 Hz data from GPS receivers over Bluetooth to Verizon XV6700 smartphones equipped with Geodetics, Inc. RTD Rover software. The smartphone transmits raw receiver data to a real-time server at the Scripps Orbit and Permanent Array Center (SOPAC) running RTD Pro. At the server, instantaneous positions are computed every second relative to the three closest base stations in the California Real Time Network (CRTN), using ultra-rapid orbits produced by SOPAC, the NOAATrop real-time tropospheric delay model, and ITRF2005 coordinates computed by SOPAC for the CRTN stations. The raw data are converted on-the-fly to RINEX format at the server. Data in both formats are stored on the server along with a file of instantaneous positions, computed independently at each observation epoch. The single-epoch instantaneous positions are continuously transmitted back to the field surveyor's smartphone, where RTD Rover computes a median position and interquartile range for each new epoch of observation. The best-fit solution is the last median position and is available as soon as the survey is completed. We describe how we used this method to process 1 Hz data from the February, 2008 Imperial Valley GPS survey of 38 geodetic monuments established by Imperial College, London in the 1970's, and previously measured by SOPAC using rapid-static GPS methods in 1993, 1999 and 2000, as well as 14 National Geodetic Survey (NGS) monuments. For redundancy, each monument was surveyed for about 15 minutes at least twice and at staggered intervals using two survey teams operating autonomously. Archiving of data and the overall project at SOPAC is performed using the PGM software, developed by the California Spatial Reference Center (CSRC) for the National Geodetic Survey (NGS). The

A time series evaluation of the FAST National Stroke Awareness Campaign in England.

Directory of Open Access Journals (Sweden)

Darren Flynn

Full Text Available In February 2009, the Department of Health in England launched the Face, Arm, Speech, and Time (FAST mass media campaign, to raise public awareness of stroke symptoms and the need for an emergency response. We aimed to evaluate the impact of three consecutive phases of FAST using population-level measures of behaviour in England.Interrupted time series (May 2007 to February 2011 assessed the impact of the campaign on: access to a national stroke charity's information resources (Stroke Association [SA]; emergency hospital admissions with a primary diagnosis of stroke (Hospital Episode Statistics for England; and thrombolysis activity from centres in England contributing data to the Safe Implementation of Thrombolysis in Stroke UK database.Before the campaign, emergency admissions (and patients admitted via accident and emergency [A&E] and thrombolysis activity was increasing significantly over time, whereas emergency admissions via general practitioners (GPs were decreasing significantly. SA webpage views, calls to their helpline and information materials dispatched increased significantly after phase one. Website hits/views, and information materials dispatched decreased after phase one; these outcomes increased significantly during phases two and three. After phase one there were significant increases in overall emergency admissions (505, 95% CI = 75 to 935 and patients admitted via A&E (451, 95% CI = 26 to 875. Significantly fewer monthly emergency admissions via GPs were reported after phase three (-19, 95% CI =  -29 to -9. Thrombolysis activity per month significantly increased after phases one (3, 95% CI = 1 to 6, and three (3, 95% CI = 1 to 4.Phase one had a statistically significant impact on information seeking behaviour and emergency admissions, with additional impact that may be attributable to subsequent phases on information seeking behaviour, emergency admissions via GPs, and thrombolysis activity. Future campaigns should be

Remote landslide mapping using a laser rangefinder binocular and GPS

Directory of Open Access Journals (Sweden)

M. Santangelo

2010-12-01

Full Text Available We tested a high-quality laser rangefinder binocular coupled with a GPS receiver connected to a Tablet PC running dedicated software to help recognize and map in the field recent rainfall-induced landslides. The system was tested in the period between March and April 2010, in the Monte Castello di Vibio area, Umbria, Central Italy. To test the equipment, we measured thirteen slope failures that were mapped previously during a visual reconnaissance field campaign conducted in February and March 2010. For reference, four slope failures were also mapped by walking the GPS receiver along the landslide perimeter. Comparison of the different mappings revealed that the geographical information obtained remotely for each landslide by the rangefinder binocular and GPS was comparable to the information obtained by walking the GPS around the landslide perimeter, and was superior to the information obtained through the visual reconnaissance mapping. Although our tests were not exhaustive, we maintain that the system is effective to map recent rainfall induced landslides in the field, and we foresee the possibility of using the same (or similar system to map landslides, and other geomorphological features, in other areas.

Present kinematics of the Tjornes Fracture Zone, North Iceland, from campaign and continuous GPS measurements

KAUST Repository

Metzger, S.; Jonsson, Sigurjon; Danielsen, G.; Hreinsdottir, S.; Jouanne, F.; Giardini, D.; Villemin, T.

2012-01-01

The improved velocity field based on 58 GPS stations confirms the robustness of our previous model and allows to better constrain the free model parameters. For the HFF we find a slightly shallower locking depth of ∼6.2 km and a slightly higher slip-rate of ∼6.8 mm yr−1 that again result in the same seismic potential equivalent to a Mw6.8 earthquake. The much larger number of GPS velocities improves the statistically estimated model parameter uncertainties by a factor of two, when compared to our previous study, a result that we validate using Bayesian estimation.

Derivation of some geometric parameters from GPS measurements

Directory of Open Access Journals (Sweden)

Marcel Mojzeš

2005-11-01

Full Text Available Combining GPS and terrestrial data requires a common coordinate system. When the original GPS vectors do not form a network, the 3D network adjustment can not be performed. In this case, in order to integrate the GPS measurements with the terrestrial observations and to perform a combined network adjustment, the GPS measurements should be transformed to this common system. The GPS measurements which are the usual output of the GPS post processing softwares are based on the WGS84 ellipsoid and the S-JTSK local datum is based on the Bessel ellipsoid. Thus, the reduction of measurements to the S-JTSK mapping plane can not be started from the measurements resulting from GPS post processing softwares because GPS and S-JTSK don’t have the same ellipsoid. Another view of this reduction will be described in this paper.

GPS/INS Sensor Fusion Using GPS Wind up Model

Science.gov (United States)

Williamson, Walton R. (Inventor)

2013-01-01

A method of stabilizing an inertial navigation system (INS), includes the steps of: receiving data from an inertial navigation system; and receiving a finite number of carrier phase observables using at least one GPS receiver from a plurality of GPS satellites; calculating a phase wind up correction; correcting at least one of the finite number of carrier phase observables using the phase wind up correction; and calculating a corrected IMU attitude or velocity or position using the corrected at least one of the finite number of carrier phase observables; and performing a step selected from the steps consisting of recording, reporting, or providing the corrected IMU attitude or velocity or position to another process that uses the corrected IMU attitude or velocity or position. A GPS stabilized inertial navigation system apparatus is also described.

Poolside fuel assembly inspection campaigns performed at Kernkraftwerk Leibstadt during summer 1997

International Nuclear Information System (INIS)

Zwicky, H.U.; Wiktor, C.G.; Schrire, D.

1998-01-01

In order to minimise fuel cycle costs, fuel assembly discharge burnup and average U-235 enrichment were increasing over past years in the Kernkraftwerk Leibstadt (KKL) plant. In parallel, high burnup verification programs were defined in collaboration with fuel suppliers. The aim of these programs is to demonstrate safe and reliable fuel performance up to the designed burnup limit and to identify any problems in due time. This is not only achieved by detailed poolside inspections of lead test assemblies, but also by hot cell post-irradiation examination of selected rods. In the frame of a hot cell examination campaign, enhanced localised corrosion in the vicinity of spacers on SVEA-96 fuel rods was identified in May 1997 as a potential problem. The average rod burnup of the investigated rods was around 50 MWd/kgU after 5 one year cycles of operation. As fuel operation up to six cycles is foreseen in KKLs fuel management plants, the risk of fuel failures caused by enhanced localised corrosion could not be excluded. An action plan was therefore developed in order to identify the root cause. Part of the action plan were two poolside inspection campaigns: 1. Visual inspection of 38 assemblies unloaded during refuelling outage 1996 after 5 cycles in operation. This campaign was performed in June 1997. It gave a broader data base to develop a concept for fuel management for the upcoming refuelling outage scheduled in August 1997. 2. Visual inspection, oxide layer thickness measurements, crud sampling and rod diameter measurements on 29 assemblies with different operation histories. This campaign was performed during the outage. A large portion of the inspected bundles was re-inserted for continued operation. The collected data confirmed that assumptions made for reload licensing and safety analyses were conservative. The inspection campaigns performed at KKL during summer 1997 by ABB Atom demonstrated that it is possible to address unexpected problems in a short time

Evaluating the performance of a low-cost GPS in precision agriculture applications

DEFF Research Database (Denmark)

Jensen, Kjeld; Larsen, Morten; Simonsen, Tom

2012-01-01

Field Robots are often equipped with a Real Time Kinematic (RTK) GPS to obtain precise positioning. In many precision agriculture applications, however, the robot operates in semi-structured environments like orchards and row crops, where local sensors such as computer vision and laser range...... scanners can produce accurate positioning relative to the crops. GPS is then primarily needed for robust inter-row navigation. This work evaluates a new low-cost GPS. Static tests were used to test the absolute accuracy. To test the GPS in a precision agriculture environment it was installed on a robot...

GPS-based system for satellite tracking and geodesy

Science.gov (United States)

Bertiger, Willy I.; Thornton, Catherine L.

1989-01-01

High-performance receivers and data processing systems developed for GPS are reviewed. The GPS Inferred Positioning System (GIPSY) and the Orbiter Analysis and Simulation Software (OASIS) are described. The OASIS software is used to assess GPS system performance using GIPSY for data processing. Consideration is given to parameter estimation for multiday arcs, orbit repeatability, orbit prediction, daily baseline repeatability, agreement with VLBI, and ambiguity resolution. Also, the dual-frequency Rogue receiver, which can track up to eight GPS satellites simultaneously, is discussed.

GPS for structural health monitoring - case study on the Basarab overpass cable-stayed bridge

Science.gov (United States)

Lepadatu, Alexandru; Tiberius, Christian

2014-04-01

The Basarab cable-stayed bridge is a newly built structure in Bucharest, Romania, which was inaugurated in June 2011. Before the oficial opening, in order to assure its qualification for trafic, it had to pass several loading tests with convoys of trucks and trams. For this, besides a priori evaluation using the Finite Element Method (FEM), levelling and acceleration measurements were made to identify vertical displacements, as well as vibration frequencies of the bridge. The three-day loading trial of the bridge represented a good opportunity for setting-up a GPS campaign for structural monitoring of the Basarab bridge. Taking advantage of the redundancy obtained via simultaneous multi-sensor measurements, it was possible to compare and validate the GPS estimated displacements with both FEM and levelling. Moreover, the dynamic behaviour of the bridge during a dynamic loading test was evaluated using a 20 Hz GPS observation rate and validated afterwards with vibration frequency estimates from acceleration time series. Along with simulations (FEM) and laboratory tests, the in situ monitoring of a structure has a particular importance in establishing the safety of a newly-built structure. Furthermore, in some cases permanent monitoring is needed for safety and economic reasons, especially for strategic structures such as dams and bridges. GPS technology can satisfy this request due to its real-time processing capability and thus it can be looked upon as a new and promising tool for dynamic evaluation of engineering structures. In this contribution we have also assessed the performance of GPS with regard to accuracy and false alarm probability demands for the continuous monitoring of the Basarab cable-stayed bridge.

Retained satellite information influences performance of GPS devices in a forested ecosystem

Science.gov (United States)

Katie M. Moriarty; Clinton W. Epps

2015-01-01

Global Positioning System (GPS) units used in animal telemetry often suffer from nonrandom data loss and location error. GPS units use stored satellite information to estimate locations, including almanac and ephemeris data reflecting satellite positions at weekly and at <4-hr temporal scales, respectively. Using the smallest GPS collars (45–51 g) available for...

Capsule performance optimization in the National Ignition Campaign

International Nuclear Information System (INIS)

Landen, O. L.; Bradley, D. K.; Braun, D. G.; Callahan, D. A.; Celliers, P. M.; Collins, G. W.; Dewald, E. L.; Divol, L.; Glenzer, S. H.; Hamza, A.; Hicks, D. G.; Izumi, N.; Jones, O. S.; Kirkwood, R. K.; Michel, P.; Milovich, J.; Munro, D. H.; Robey, H. F.; Spears, B. K.; Thomas, C. A.

2010-01-01

A capsule performance optimization campaign will be conducted at the National Ignition Facility [G. H. Miller et al., Nucl. Fusion 44, 228 (2004)] to substantially increase the probability of ignition by laser-driven hohlraums [J. D. Lindl et al., Phys. Plasmas 11, 339 (2004)]. The campaign will experimentally correct for residual uncertainties in the implosion and hohlraum physics used in our radiation-hydrodynamic computational models before proceeding to cryogenic-layered implosions and ignition attempts. The required tuning techniques using a variety of ignition capsule surrogates have been demonstrated at the OMEGA facility under scaled hohlraum and capsule conditions relevant to the ignition design and shown to meet the required sensitivity and accuracy. In addition, a roll-up of all expected random and systematic uncertainties in setting the key ignition laser and target parameters due to residual measurement, calibration, cross-coupling, surrogacy, and scale-up errors has been derived that meets the required budget.

75 FR 8928 - Announcement of IS-GPS-200, IS-GPS-705, IS-GPS-800 Interface Control Working Group (ICWG...

Science.gov (United States)

2010-02-26

... DEPARTMENT OF DEFENSE Department of the Air Force Announcement of IS-GPS-200, IS-GPS-705, IS-GPS... document/s IS-GPS-200E (NAVSTAR GPS Space Segment/Navigation User Interfaces), IS-GPS-705A (NAVSTAR GPS Space Segment/User Segment L5 Interfaces), and IS-GPS-800A (NAVSTAR GPS Space Segment/User Segment L1C...

Comparison of an inflammation-based prognostic score (GPS) with performance status (ECOG-ps) in patients receiving palliative chemotherapy for gastroesophageal cancer.

Science.gov (United States)

Crumley, Andrew B C; Stuart, Robert C; McKernan, Margaret; McDonald, Alexander C; McMillan, Donald C

2008-08-01

The aim of the present study was to compare an inflammation-based prognostic score (Glasgow Prognostic Score, GPS) with performance status (ECOG-ps) in patients receiving platinum-based chemotherapy for palliation of gastroesophageal cancer. Sixty-five patients presenting with gastroesophageal carcinoma to the Royal Infirmary, Glasgow between January 1999 and December 2005 and who received palliative chemotherapy or chemo-radiotherapy were studied. ECOG-ps, C-reactive protein, and albumin were recorded at diagnosis. Patients with both an elevated C-reactive protein (>10 mg/L) and hypoalbuminemia (L) were allocated a GPS of 2. Patients in whom only one of these biochemical abnormalities was present were allocated a GPS of 1 and patients with a normal C-reactive protein and albumin were allocated a score of 0. Toxicity was recorded using the Common Toxicity Criteria. The minimum follow up was 14 months. During the follow-up period, 59 (91%) of the patients died. On univariate and multivariate survival analysis, only the GPS (hazard ratios 1.65, 95% CI 1.10-2.47, P GPS of 0, those patients with a GPS of 1 or 2 required more frequent chemotherapy dose reduction (P GPS, appears to be superior to the subjective assessment of performance status (ECOG-ps) in predicting the response to platinum-based chemotherapy in patients with advanced gastroesophageal cancer.

Tectonic Model of Bali Island Inferred from GPS Data

Directory of Open Access Journals (Sweden)

Cecep Sulaeman

2018-01-01

Full Text Available DOI: 10.17014/ijog.5.1.81-91Seven periods of GPS campaign have been conducted for three years since March 2013 - October 2015 on fourteen GPS sites across Bali Island. The GAMIT/GLOBK 10.6 version was used to compute data with respect for thirteen reference sites of International Terrestrial Reference Frame (ITRF 2008 surrounding Bali. The result shows that horizontal displacement varies between 1.93 and 22.53 mm/yr dominantly northeastward. Vertical displacement ranges at -184.34 to 33.79 mm/yr. The result of modeling using Coulomb 3.3 version indicates the deformation in Bali was mostly contributed by subduction at the southern part, West and East Flores Back-Arc Thrust at the north, Lombok Strait Fault and a fault at the eastern coast of Bali with the estimation maximum magnitude of 7.1, 6.6, 6.8, 5.8, and 5.2, respectively.

Scintillation-Hardened GPS Receiver

Science.gov (United States)

Stephens, Donald R.

2015-01-01

CommLargo, Inc., has developed a scintillation-hardened Global Positioning System (GPS) receiver that improves reliability for low-orbit missions and complies with NASA's Space Telecommunications Radio System (STRS) architecture standards. A software-defined radio (SDR) implementation allows a single hardware element to function as either a conventional radio or as a GPS receiver, providing backup and redundancy for platforms such as the International Space Station (ISS) and high-value remote sensing platforms. The innovation's flexible SDR implementation reduces cost, weight, and power requirements. Scintillation hardening improves mission reliability and variability. In Phase I, CommLargo refactored an open-source GPS software package with Kalman filter-based tracking loops to improve performance during scintillation and also demonstrated improved navigation during a geomagnetic storm. In Phase II, the company generated a new field-programmable gate array (FPGA)-based GPS waveform to demonstrate on NASA's Space Communication and Navigation (SCaN) test bed.

Continued Trenchward Procession of Upper Plate GPS Sites Following the 2012 Mw 7.6 Nicoya Earthquake

Science.gov (United States)

Hobbs, T. E.; Newman, A. V.; Protti, M.

2015-12-01

When studying subduction zone deformation one is often forced to consider a region significantly landward of the trench. The Nicoya Peninsula in Costa Rica presents a unique opportunity to obtain rich datasets from land in relatively close proximity to an active megathrust. A recent moment magnitude (Mw) 7.6 earthquake in September 2012 on this portion of the Middle America Trench affords an opportunity to constrain the ongoing postseismic deformation on the subduction interface between the Cocos and Caribbean plates. GPS campaigns occupying 22 sites were undertaken immediately following the earthquake in September-December 2012 and most recently in March 2015. Combined with data from a network of 17 continuous GPS in the region, we analyze the spatial and temporal changes in the postseismic velocity field. Another campaign is planned for 2017, in conjunction with our ongoing analysis of the continuous GPS network. After 2.5 years, campaign GPS results indicate significant trenchward motion of at least 7 cm, relative to a fixed Caribbean plate, for all sites up to the volcanic chain. Maximum values of 22 cm are observed above and updip of the coseismic rupture zone. The trench-parallel component of the displacement field is small, with few deviations between sites. Together these observations are substantially more self-similar over a larger region than what was observed for the coseismic offset. This implies that there may be a low stress differential across the upper plate, suggesting that the subduction interface environment, including the mainshock and surrounding area, has remained relatively weak following the earthquake. By utilizing a dense and long-term geodetic network we will report on initial modeling that aims to characterize the evolution of afterslip. The effect of regional aftershocks, including an Mw 6.5 in October 2012, and viscoelastic mantle relaxation will be considered to establish the necessity of such effects in robustly accounting for

New insights in geodynamics of wider Zagreb area: results of GPS measurements series 2009 on Zagreb Geodynamic Network

Science.gov (United States)

Pribičević, Boško; Medak, Damir; ĐApo, Almin

2010-05-01

The Geodynamic GPS-Network of the City of Zagreb represents the longest and the most intensive research effort in the field of geodynamics in Croatia. Since the establishment of the Network in 1997, several series of precise GPS measurements have been conducted on specially stabilized points of Geodynamical Network of City of Zagreb with purpose of investigation of tectonic movements and related seismic activity of the wider area of the City of Zagreb. The Network has been densified in 2005 in the most active region of northeastern Mount Medvednica. Since then, several GPS campaigns have been conducted including the last in summer 2009. The paper presents latest results of geodynamic movements of the network points.

Pre- and post-flight radiation performance evaluation of the space GPS receiver (SGR)

International Nuclear Information System (INIS)

Oldfield, M.K.; Underwood, C.I.; Unwin, M.J.; Asenek, V.; Harboe-Sorensen, R.

1999-01-01

SSTL (Survey Satellite Technology Ltd), in collaboration with ESA/ESTEC, recently developed a state-of-the-art low cost GPS (Global Positioning System) receiver payload for use on small satellites. The space GPS Receiver (SGR), will be flown on the TiungSAT-1 micro-satellite, UoSAT-12 mini-satellite and ESA's PROBA satellite. The SGR payload is currently flying on the TMSAT micro-satellite in low Earth orbit (LEO) and has carried out autonomous on-board positioning whilst also providing an experimental test-bed for evaluating spacecraft attitude determination algorithms. In order to reduce development time and costs, the SGR consists solely of industry standard COTS (commercial off-the-shelf) devices. This paper describes the ground-based radiation testing of several payload-critical COTS devices used in the SGR payload and describes its on-orbit performance. (authors)

A GPS Phase-Locked Loop Performance Metric Based on the Phase Discriminator Output.

Science.gov (United States)

Stevanovic, Stefan; Pervan, Boris

2018-01-19

We propose a novel GPS phase-lock loop (PLL) performance metric based on the standard deviation of tracking error (defined as the discriminator's estimate of the true phase error), and explain its advantages over the popular phase jitter metric using theory, numerical simulation, and experimental results. We derive an augmented GPS phase-lock loop (PLL) linear model, which includes the effect of coherent averaging, to be used in conjunction with this proposed metric. The augmented linear model allows more accurate calculation of tracking error standard deviation in the presence of additive white Gaussian noise (AWGN) as compared to traditional linear models. The standard deviation of tracking error, with a threshold corresponding to half of the arctangent discriminator pull-in region, is shown to be a more reliable/robust measure of PLL performance under interference conditions than the phase jitter metric. In addition, the augmented linear model is shown to be valid up until this threshold, which facilitates efficient performance prediction, so that time-consuming direct simulations and costly experimental testing can be reserved for PLL designs that are much more likely to be successful. The effect of varying receiver reference oscillator quality on the tracking error metric is also considered.

GPS-Based Highway Performance Monitoring Performance Monitoring Using GPS: Characterization of Travel Speeds on any Roadway Segment

OpenAIRE

Kornhauser, Alain L.

2012-01-01

Presented is a characterization of travel speed on any roadway segment based on probe vehicle position data. Most of the characterization is based position data obtained from GPS receivers because of their high precision and their increasing availability. Comparison is also made to Qualcomm’s Automatic Satellite Position Reporting (QASPR) system because of its long history (10+ years) of extensive use by the long-haul trucking industry. Described is the use of these data in conjunction with d...

GPS crustal deformation of the Eastern Betics and its relationship with the Lorca earthquake; Deformacion cortical de las Beticas Orientales observada mediante GPS y su relacion con el terremoto de Lorca

Energy Technology Data Exchange (ETDEWEB)

Echeverria, A.; Khazaradze, G.; Asensio, E.; Garate, J.; Surinach, E.

2012-07-01

On May 11{sup t}h of 2011, a seismic series occurred near the city of Lorca (Murcia). The main earthquake of magnitude Mw 5.2 has been attributed to the Alhama de Murcia Fault, one of the most active faults in the SE Iberian Peninsula. We analyzed data from 5 GPS campaigns of the CuaTeNeo network conducted between 1997 and 2011. The velocities of the stations closest to the Alhama de Murcia Fault show the reverse and strike-slip direction of motion. Stations located on the southeastern side of the fault have the maximum velocities in the area (between 1.4 and 1.8 mm/yr), oriented towards NNW direction, obliquely to the trace of the fault. The kinematics of the fault and the strain rate directions obtained from the CuaTeNeo network GPS measurements matches the calculated focal mechanism of Lorca earthquake. Detailed analysis of the time-series from the continuous GPS station at the Lorca city allows the detection of co-seismic offset of {approx}6 mm to the North. Keywords: crustal deformation, GPS, Betics, Lorca earthquake. (Author) 20 refs.

VLBI and GPS-based Time-Transfer Using CONT08 Data

Science.gov (United States)

Rieck, Carsten; Haas, Ruediger; Jaldehag, Kenneth; Jahansson, Jan

2010-01-01

One important prerequisite for geodetic Very Long Baseline Interferometry (VLBI) is the use of frequency standards with excellent short term stability. This makes VLBI stations, which are often co-located with Global Navigation Satellite System (GNSS) receiving stations, interesting for studies of time- and frequency-transfer techniques. We present an assessment of VLBI time-transfer based on the data of the two week long consecutive IVS CONT08 VLBI campaign by using GPS Carrier Phase (GPSCP). CONT08 was a 15 day long campaign in August 2008 that involved eleven VLBI stations on five continents. For CONT08 we estimated the worst case VLBI frequency link stability between the stations of Onsala and Wettzell to 1e-15 at one day. Comparisons with GPSCP confirm the VLBI results. We also identify time-transfer related challenges of the VLBI technique as used today.

Integrated navigation of aerial robot for GPS and GPS-denied environment

International Nuclear Information System (INIS)

Suzuki, Satoshi; Min, Hongkyu; Nonami, Kenzo; Wada, Tetsuya

2016-01-01

In this study, novel robust navigation system for aerial robot in GPS and GPS- denied environments is proposed. Generally, the aerial robot uses position and velocity information from Global Positioning System (GPS) for guidance and control. However, GPS could not be used in several environments, for example, GPS has huge error near buildings and trees, indoor, and so on. In such GPS-denied environment, Laser Detection and Ranging (LIDER) sensor based navigation system have generally been used. However, LIDER sensor also has an weakness, and it could not be used in the open outdoor environment where GPS could be used. Therefore, it is desired to develop the integrated navigation system which is seamlessly applied to GPS and GPS-denied environments. In this paper, the integrated navigation system for aerial robot using GPS and LIDER is developed. The navigation system is designed based on Extended Kalman Filter, and the effectiveness of the developed system is verified by numerical simulation and experiment. (paper)

Development of a low cost, GPS-based upgrade to a standard handheld gamma detector for mapping environmental radioactive contamination

International Nuclear Information System (INIS)

Paridaens, J.

2006-01-01

A low cost extension to a standard handheld radiation monitor was developed, allowing one to perform outdoor georeferenced gamma measurements. It consists of a commercial wireless Bluetooth[reg] GPS receiver, a commercial RS-232 to Bluetooth[reg] converter combined with a standard Bluetooth[reg] enabled pocket personal computer (PPC). The system is intended for use in difficult to access areas, typically for foot campaigns. As the operator walks, a straightforward homemade visual basic program alternately reads GPS position and gamma dose rate into the PPC, creating a data log. This allows a single operator on foot to map between 50 and 200 ha of environmental radiation per day in very rugged areas, depending on the accessibility of the terrain and the detail required. On a test field with known contamination, a spatial precision of about 5-10 m was obtainable. The device was also used to reveal complex contamination patterns in the flooding zones of a radioactively contaminated small river

Development of a low cost, GPS-based upgrade to a standard handheld gamma detector for mapping environmental radioactive contamination.

Science.gov (United States)

Paridaens, J

2006-02-01

A low cost extension to a standard handheld radiation monitor was developed, allowing one to perform outdoor georeferenced gamma measurements. It consists of a commercial wireless Bluetooth GPS receiver, a commercial RS-232 to Bluetooth converter combined with a standard Bluetooth enabled pocket personal computer (PPC). The system is intended for use in difficult to access areas, typically for foot campaigns. As the operator walks, a straightforward homemade visual basic program alternately reads GPS position and gamma dose rate into the PPC, creating a data log. This allows a single operator on foot to map between 50 and 200 ha of environmental radiation per day in very rugged areas, depending on the accessibility of the terrain and the detail required. On a test field with known contamination, a spatial precision of about 5-10 m was obtainable. The device was also used to reveal complex contamination patterns in the flooding zones of a radioactively contaminated small river.

Development of a low cost, GPS-based upgrade to a standard handheld gamma detector for mapping environmental radioactive contamination

Energy Technology Data Exchange (ETDEWEB)

Paridaens, J. [Belgian Nuclear Research Centre, SCK.CEN, Boeretang 200, B2400 Mol (Belgium)]. E-mail: jparidae@sckcen.be

2006-02-15

A low cost extension to a standard handheld radiation monitor was developed, allowing one to perform outdoor georeferenced gamma measurements. It consists of a commercial wireless Bluetooth[reg] GPS receiver, a commercial RS-232 to Bluetooth[reg] converter combined with a standard Bluetooth[reg] enabled pocket personal computer (PPC). The system is intended for use in difficult to access areas, typically for foot campaigns. As the operator walks, a straightforward homemade visual basic program alternately reads GPS position and gamma dose rate into the PPC, creating a data log. This allows a single operator on foot to map between 50 and 200 ha of environmental radiation per day in very rugged areas, depending on the accessibility of the terrain and the detail required. On a test field with known contamination, a spatial precision of about 5-10 m was obtainable. The device was also used to reveal complex contamination patterns in the flooding zones of a radioactively contaminated small river.

GPS Composite Clock Analysis

OpenAIRE

Wright, James R.

2008-01-01

The GPS composite clock defines GPS time, the timescale used today in GPS operations. GPS time is illuminated by examination of its role in the complete estimation and control problem relative to UTC/TAI. The phase of each GPS clock is unobservable from GPS pseudorange measurements, and the mean phase of the GPS clock ensemble (GPS time) is unobservable. A new and useful observability definition is presented, together with new observability theorems, to demonstrate explicitly that GPS time is...

An Introduction to the Tibet cGPS pilot project: TigiCAS

Science.gov (United States)

Zhang, Z.; Liu, J.; Galetzka, J.; Avouac, J.; Tapponnier, P.; Zeng, L.; Gan, W.; Shen, Z.; Wang, M.

2007-12-01

The convergence between India and Eurasia is the¡¡prototype of continental collision in action. Compared¡¡to geological history and fault kinematics studies, the present-day, regional pattern of strain-partitioning¡¡is still inadequately known. Among limited geodetic¡¡efforts in the past decade or two, most have been focused¡¡on refining measurements of the current crustal¡¡shortening rate across the Himalaya. The vast region¡¡immediately to the north is sparsely instrumented, with only one continuous GPS station (Lhasa) within¡¡the plateau proper. Campaign stations are few and¡¡ill-positioned, mostly along major roads, providing¡¡poor constraints on present-day slip-rates on individual¡¡active faults. The extant GPS network configuration is thus still insufficient to discriminate between block vs continuum deformation. In November 2006, the¡¡Chinese Academy of Sciences led a pilot program and¡¡installed 6 continuous GPS stations in southern Tibet, crossing the NS-trending normal fault systems and¡¡complementing the Nepal cGPS profiles. We present¡¡here the new sites, preliminary data processing results, and the spatial relationship with ongoing or planned¡¡continuous GPS sites from a couple of other projects. Together with such projects, TigiCAS will provide¡¡a substantial increase in geodetic data in the¡¡Himalayan-Tibet convergent belt in the next few¡¡years, and lead to a better understanding of¡¡contemporary deformation of the region.

Forearc Sliver Translation, a Lack of Arc-Normal Strain Accumulation, and Interplate Thrust Earthquakes: GPS Geodesy in Western Nicaragua

Science.gov (United States)

Turner, H. L.; Mattioli, G. S.; Jansma, P. E.; Styron, R. H.

2007-05-01

We have been investigating the kinematics of the Nicaraguan forearc using campaign GPS measurements of our geodetic network made over the last seven years (Turner et al., 2007). We currently have interseismic velocities for 18 campaign sites and have installed 10 additional sites in the backarc to investigate the nature of the transition from forearc sliver motion to stable Caribbean Plate motion. Our work focusing on the later issue is presented elsewhere at this meeting (Styron et al., 2007). Corrections for modeled coseismic offsets from the Jan. 13, 2001 Mw7.7 earthquake off the coast of El Salvador have been applied to our campaign site velocities. Some of our time-series are also strongly affected by coseismic and postseismic effects of the Oct. 9, 2004 Mw6.9 earthquake off of the coast of Nicaragua. The geodetic effects of this event are being removed from the affected time-series for interseismic velocity analysis. We have also derived interseismic velocities for five continuous GPS sites in the region. Our GPS results confirm previous predictions of northwest transport of a forearc sliver with an average Northwest velocity of ~15 mm yr-1, but show little evidence for an arc- normal component of strain accumulation associated with locking on the subduction interface. However, the amount of seismicity along this section of the Middle America Trench, including several recent large events such as the 1992 Mw7.6 and 2004 Mw6.9 earthquakes, indicates some amount of locking is present. Several possibilities may account for the apparent contradiction between the GPS results and observed seismicity. The locked zone may be too shallow and too far offshore for the arc-normal component to show up in our network, or the arc-normal signal may be masked by post-seismic effects from the 1992 offshore earthquake. If coupling between the downgoing slab and the overriding plate is weak or limited to a small seismogenic zone, then arc-parallel motion of the forearc sliver may

Performance Analysis of Low-Cost Single-Frequency GPS Receivers in Hydrographic Surveying

Science.gov (United States)

Elsobeiey, M.

2017-10-01

The International Hydrographic Organization (IHO) has issued standards that provide the minimum requirements for different types of hydrographic surveys execution to collect data to be used to compile navigational charts. Such standards are usually updated from time to time to reflect new survey techniques and practices and must be achieved to assure both surface navigation safety and marine environment protection. Hydrographic surveys can be classified to four orders namely, special order, order 1a, order 1b, and order 2. The order of hydrographic surveys to use should be determined in accordance with the importance to the safety of navigation in the surveyed area. Typically, geodetic-grade dual-frequency GPS receivers are utilized for position determination during data collection in hydrographic surveys. However, with the evolution of high-sensitivity low-cost single-frequency receivers, it is very important to evaluate the performance of such receivers. This paper investigates the performance of low-cost single-frequency GPS receivers in hydrographic surveying applications. The main objective is to examine whether low-cost single-frequency receivers fulfil the IHO standards for hydrographic surveys. It is shown that the low-cost single-frequency receivers meet the IHO horizontal accuracy for all hydrographic surveys orders at any depth. However, the single-frequency receivers meet only order 2 requirements for vertical accuracy at depth more than or equal 100 m.

Reinforced Ultra-Tightly Coupled GPS/INS System for Challenging Environment

Directory of Open Access Journals (Sweden)

Xueyun Wang

2014-01-01

Full Text Available Among all integration levels currently available for Global Positioning System (GPS and Inertial Navigation System (INS Integrated System, ultra-tightly coupled (UTC GPS/INS system is the best choice for accurate and reliable navigation. Nevertheless the performance of UTC GPS/INS system degrades in challenging environments, such as jamming, changing noise of GPS signals, and high dynamic maneuvers. When low-end Inertial Measurement Units (IMUs based on MEMS sensors are employed, the performance degradation will be more severe. To solve this problem, a reinforced UTC GPS/INS system is proposed. Two techniques are adopted to deal with jamming and high dynamics. Firstly, adaptive integration Kalman filter (IKF based on fuzzy logics is developed to reinforce the antijamming ability. The parameters of membership functions (MFs are adjusted and optimized through self-developed neutral network. Secondly, a Doppler frequency error estimator based on Kalman filter is designed to improve the navigation performance under high dynamics. A complete simulation platform is established to evaluate the reinforced system. Results demonstrate that the proposed system architecture significantly improves navigation performance in challenging environments and it is a more advanced solution to accurate and reliable navigation than traditional UTC GPS/INS system.

Kinematic-PPP using Single/Dual Frequency Observations from (GPS, GLONASS and GPS/GLONASS) Constellations for Hydrography

Science.gov (United States)

Farah, Ashraf

2018-03-01

Global Positioning System (GPS) technology is ideally suited for inshore and offshore positioning because of its high accuracy and the short observation time required for a position fix. Precise point positioning (PPP) is a technique used for position computation with a high accuracy using a single GNSS receiver. It relies on highly accurate satellite position and clock data that can be acquired from different sources such as the International GNSS Service (IGS). PPP precision varies based on positioning technique (static or kinematic), observations type (single or dual frequency) and the duration of observations among other factors. PPP offers comparable accuracy to differential GPS with safe in cost and time. For many years, PPP users depended on GPS (American system) which considered the solely reliable system. GLONASS's contribution in PPP techniques was limited due to fail in maintaining full constellation. Yet, GLONASS limited observations could be integrated into GPS-based PPP to improve availability and precision. As GLONASS reached its full constellation early 2013, there is a wide interest in PPP systems based on GLONASS only and independent of GPS. This paper investigates the performance of kinematic PPP solution for the hydrographic applications in the Nile river (Aswan, Egypt) based on GPS, GLONASS and GPS/GLONASS constellations. The study investigates also the effect of using two different observation types; single-frequency and dual frequency observations from the tested constellations.

Tidal Modulation of Ice Flow on Kangerdlugssuaq and Helheim Glaciers, East Greenland, from High-Rate GPS Measurements

DEFF Research Database (Denmark)

Hamilton, G. S.; Stearns, L. A.; Elosegui, P.

knowledge of ice thickness and fjord bathymetry. Here, we use high-rate GPS measurements collected at sites within a few km of the calving fronts of Kangerdlugssuaq and Helheim glaciers to examine the effect of ocean tide on ice flow. Data were collected at 5-15 s sampling rate during several campaign...... appears to have a short floating tongue, based on an analysis of GPS data collected in June-August 2006 at several stations located at increasing distances from the calving front. Glacier uplift was in phase with measured and modeled tidal height, but attenuated rapidly beyond ~~1 km from the terminus. We...

Newly velocity field of Sulawesi Island from GPS observation

Science.gov (United States)

Sarsito, D. A.; Susilo, Simons, W. J. F.; Abidin, H. Z.; Sapiie, B.; Triyoso, W.; Andreas, H.

2017-07-01

Sulawesi microplate Island is located at famous triple junction area of the Eurasian, India-Australian, and Philippine Sea plates. Under the influence of the northward moving Australian plate and the westward motion of the Philippine plate, the island at Eastern part of Indonesia is collide and with the Eurasian plate and Sunda Block. Those recent microplate tectonic motions can be quantitatively determine by GNSS-GPS measurement. We use combine GNSS-GPS observation types (campaign type and continuous type) from 1997 to 2015 to derive newly velocity field of the area. Several strategies are applied and tested to get the optimum result, and finally we choose regional strategy to reduce error propagation contribution from global multi baseline processing using GAMIT/GLOBK 10.5. Velocity field are analyzed in global reference frame ITRF 2008 and local reference frame by fixing with respect alternatively to Eurasian plate - Sunda block, India-Australian plate and Philippine Sea plates. Newly results show dense distribution of velocity field. This information is useful for tectonic deformation studying in geospatial era.

Use and Protection of GPS Sidelobe Signals for Enhanced Navigation Performance in High Earth Orbit

Science.gov (United States)

Parker, Joel J. K.; Valdez, Jennifer E.; Bauer, Frank H.; Moreau, Michael C.

2016-01-01

GPS (Global Positioning System) Space Service Volume (SSV) signal environment is from 3,000-36,000 kilometers altitude. Current SSV specifications only capture performance provided by signals transmitted within 23.5(L1) or 26(L2-L5) off-nadir angle. Recent on-orbit data lessons learned show significant PNT (Positioning, Navigation and Timing) performance improvements when the full aggregate signal is used. Numerous military civil operational missions in High Geosynchronous Earth Orbit (HEOGEO) utilize the full signal to enhance vehicle PNT performance

Sensing and Classifying Impairments of GPS Reception on Mobile Devices

DEFF Research Database (Denmark)

Blunck, Henrik; Kjærgaard, Mikkel Baun; Toftegaard, Thomas Skjødeberg

2011-01-01

Positioning using GPS receivers is a primary sensing modality in many areas of pervasive computing. However, previous work has not considered how people’s body impacts the availability and accuracy of GPS positioning and for means to sense such impacts. We present results that the GPS performance...

Motion of the Bird's Head Block and co-seismic deformation from GPS data

Science.gov (United States)

Tikku, A. A.; Subarya, C.; N/A, M.; McCaffrey, R.; Genrich, J.

2006-05-01

The Bird's Head region of Eastern Indonesia, comprising the western end of New Guinea, behaves as an independent block at a juncture of subduction zones. It is bound on the north by the Manokwari and New Guinea Trenches, on the west by the Sorong fault, on the southwest by the Seram Trough, and on the east and southeast by the Lowland fault. Previous analysis of regional campaign global positioning system [GPS] data collected between 1991 and 1997 revealed rotation of the Bird's Head Block and high shear rates between the Pacific and Australian plates accommodated within the block. We have collected and analyzed additional regional campaign GPS data collected between 1998 and 2005, which includes data from newly established stations in the vicinity of the Cenderwasih Bay and Lowlands fault. During this span of time there were four large (Mw greater than 7.0) earthquakes in the region: a magnitude Mw=7.5 on a historically inactive NW-SE trending strike-slip fault bounding the western end of the Cenderwasih Bay on October 10th, 2002, two events, with magnitudes Mw=7.0 and 7.3, separated by a time span of two days (February 5th and 7th 2004) and a distance of ~100 km on the NE-SW trending Lowlands fault, and a third event (Mw=7.1) on November 26th 2004, coincident with the location of the February 5th 2004 event on the Lowlands fault. Destruction and fatalities were associated with all these large earthquakes. The Lowlands fault is a known seismically active fault. The historically inactive fault active that ruptured in 2002 is in the middle of the Bird's Head Block and disrupted the collection of a long seismically quiescent time-series of deformation within the block, but we have been able to constrain the co-seismic slip on this fault with the GPS data and modeling, and here present these results. We have also estimated the corruption of the co-seismic deformation from the 2002 and 2004 earthquakes and removed these from the campaign data to here present estimates

Robust GPS autonomous signal quality monitoring

Science.gov (United States)

Ndili, Awele Nnaemeka

The Global Positioning System (GPS), introduced by the U.S. Department of Defense in 1973, provides unprecedented world-wide navigation capabilities through a constellation of 24 satellites in global orbit, each emitting a low-power radio-frequency signal for ranging. GPS receivers track these transmitted signals, computing position to within 30 meters from range measurements made to four satellites. GPS has a wide range of applications, including aircraft, marine and land vehicle navigation. Each application places demands on GPS for various levels of accuracy, integrity, system availability and continuity of service. Radio frequency interference (RFI), which results from natural sources such as TV/FM harmonics, radar or Mobile Satellite Systems (MSS), presents a challenge in the use of GPS, by posing a threat to the accuracy, integrity and availability of the GPS navigation solution. In order to use GPS for integrity-sensitive applications, it is therefore necessary to monitor the quality of the received signal, with the objective of promptly detecting the presence of RFI, and thus provide a timely warning of degradation of system accuracy. This presents a challenge, since the myriad kinds of RFI affect the GPS receiver in different ways. What is required then, is a robust method of detecting GPS accuracy degradation, which is effective regardless of the origin of the threat. This dissertation presents a new method of robust signal quality monitoring for GPS. Algorithms for receiver autonomous interference detection and integrity monitoring are demonstrated. Candidate test statistics are derived from fundamental receiver measurements of in-phase and quadrature correlation outputs, and the gain of the Active Gain Controller (AGC). Performance of selected test statistics are evaluated in the presence of RFI: broadband interference, pulsed and non-pulsed interference, coherent CW at different frequencies; and non-RFI: GPS signal fading due to physical blockage and

Arctic Tides from GPS on sea-ice

DEFF Research Database (Denmark)

Kildegaard Rose, Stine; Skourup, Henriette; Forsberg, René

2013-01-01

The presence of sea-ice in the Arctic Ocean plays a significant role in the Arctic climate. Sea-ice dampens the ocean tide amplitude with the result that global tidal models perform less accurately in the polar regions. This paper presents, a kinematic processing of global positioning system (GPS....... The results show coherence between the GPS buoy measurements, and the tide model. Furthermore, we have proved that the reference ellipsoid of WGS84, can be interpolated to the tidal defined zero level by applying geophysical corrections to the GPS data....

Performance analysis of a GPS Interferometric attitude determination system for a gravity gradient stabilized spacecraft. M.S. Thesis

Science.gov (United States)

Stoll, John C.

1995-01-01

The performance of an unaided attitude determination system based on GPS interferometry is examined using linear covariance analysis. The modelled system includes four GPS antennae onboard a gravity gradient stabilized spacecraft, specifically the Air Force's RADCAL satellite. The principal error sources are identified and modelled. The optimal system's sensitivities to these error sources are examined through an error budget and by varying system parameters. The effects of two satellite selection algorithms, Geometric and Attitude Dilution of Precision (GDOP and ADOP, respectively) are examined. The attitude performance of two optimal-suboptimal filters is also presented. Based on this analysis, the limiting factors in attitude accuracy are the knowledge of the relative antenna locations, the electrical path lengths from the antennae to the receiver, and the multipath environment. The performance of the system is found to be fairly insensitive to torque errors, orbital inclination, and the two satellite geometry figures-of-merit tested.

In-flight performance analysis of MEMS GPS receiver and its application to precise orbit determination of APOD-A satellite

Science.gov (United States)

Gu, Defeng; Liu, Ye; Yi, Bin; Cao, Jianfeng; Li, Xie

2017-12-01

An experimental satellite mission termed atmospheric density detection and precise orbit determination (APOD) was developed by China and launched on 20 September 2015. The micro-electro-mechanical system (MEMS) GPS receiver provides the basis for precise orbit determination (POD) within the range of a few decimetres. The in-flight performance of the MEMS GPS receiver was assessed. The average number of tracked GPS satellites is 10.7. However, only 5.1 GPS satellites are available for dual-frequency navigation because of the loss of many L2 observations at low elevations. The variations in the multipath error for C1 and P2 were estimated, and the maximum multipath error could reach up to 0.8 m. The average code noises are 0.28 m (C1) and 0.69 m (P2). Using the MEMS GPS receiver, the orbit of the APOD nanosatellite (APOD-A) was precisely determined. Two types of orbit solutions are proposed: a dual-frequency solution and a single-frequency solution. The antenna phase center variations (PCVs) and code residual variations (CRVs) were estimated, and the maximum value of the PCVs is 4.0 cm. After correcting the antenna PCVs and CRVs, the final orbit precision for the dual-frequency and single-frequency solutions were 7.71 cm and 12.91 cm, respectively, validated using the satellite laser ranging (SLR) data, which were significantly improved by 3.35 cm and 25.25 cm. The average RMS of the 6-h overlap differences in the dual-frequency solution between two consecutive days in three dimensions (3D) is 4.59 cm. The MEMS GPS receiver is the Chinese indigenous onboard receiver, which was successfully used in the POD of a nanosatellite. This study has important reference value for improving the MEMS GPS receiver and its application in other low Earth orbit (LEO) nanosatellites.

GPS Navigation Above 76,000 km for the MMS Mission

Science.gov (United States)

Winternitz, Luke; Bamford, Bill; Price, Samuel; Long, Anne; Farahmand, Mitra; Carpenter, Russell

2016-01-01

NASA's MMS mission, launched in March of 2015,consists of a controlled formation of four spin-stabilized spacecraft in similar highly elliptic orbits reaching apogee at radial distances of 12and 25 Earth radii in the first and second phases of the mission. Navigation for MMS is achieved independently onboard each spacecraft by processing GPS observables using NASA GSFC's Navigator GPS receiver and the Goddard Enhanced Onboard Navigation System (GEONS) extended Kalman filter software. To our knowledge, MMS constitutes, by far, the highest-altitude operational use of GPS to date and represents the culmination of over a decade of high-altitude GPS navigation research and development at NASA GSFC. In this paper we will briefly describe past and ongoing high-altitude GPS research efforts at NASA GSFC and elsewhere, provide details on the design of the MMS GPS navigation system, and present on-orbit performance data. We extrapolate these results to predict performance in the Phase 2b mission orbit, and conclude with a discussion of the implications of the MMS results for future high-altitude GPS navigation, which we believe to be broad and far-reaching.

Scanning Raman lidar for tropospheric water vapor profiling and GPS path delay correction

Science.gov (United States)

Tarniewicz, Jerome; Bock, Olivier; Pelon, Jacques R.; Thom, Christian

2002-01-01

The design of a ground based and transportable combined Raman elastic-backscatter lidar for the remote sensing of lower tropospheric water vapor and nitrogen concentration is described. This lidar is intended to be used for an external calibration of the wet path delay of GPS signals. A description of the method used to derive water vapor and nitrogen profiles in the lower troposphere is given. The instrument has been tested during the ESCOMPTE campaign in June 2001 and first measurements are presented.

GPS test range mission planning

Science.gov (United States)

Roberts, Iris P.; Hancock, Thomas P.

The principal features of the Test Range User Mission Planner (TRUMP), a PC-resident tool designed to aid in deploying and utilizing GPS-based test range assets, are reviewed. TRUMP features time history plots of time-space-position information (TSPI); performance based on a dynamic GPS/inertial system simulation; time history plots of TSPI data link connectivity; digital terrain elevation data maps with user-defined cultural features; and two-dimensional coverage plots of ground-based test range assets. Some functions to be added during the next development phase are discussed.

Results from the JPL IGS Analysis Center IGS14 Reprocessing Campaign

Science.gov (United States)

Ries, P. A.; Amiri, N.; Heflin, M. B.; Sakumura, C.; Sibois, A. E.; Sibthorpe, A.; David, M. W.

2017-12-01

The JPL IGS analysis center has begun a campaign to reprocess GPS orbits and clocks in the IGS14 reference frame. Though the new frame is only a few millimeters offset from the previous IGb08 frame, a reprocessing is required for consistent use of the new frame due to a change in the satellite phase center offsets between the frames. We will present results on the reprocessing campaign from 2002 to present in order to evaluate any effects caused by the new frame. We also create long-term time-series and periodograms of translation, rotation, and scale parameters to see if there is any divergence between the frames. We will also process long-term PPP time series and derived velocities for a well-distributed set of stations in each frame to compare with the published frame offsets.

Data Integration from GPS and Inertial Navigation Systems for Pedestrians in Urban Area

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Krzysztof Bikonis

2013-09-01

Full Text Available The GPS system is widely used in navigation and the GPS receiver can offer long-term stable absolute positioning information. The overall system performance depends largely on the signal environments. The position obtained from GPS is often degraded due to obstruction and multipath effect caused by buildings, city infrastructure and vegetation, whereas, the current performance achieved by inertial navigation systems (INS is still relatively poor due to the large inertial sensor errors. The complementary features of GPS and INS are the main reasons why integrated GPS/INS systems are becoming increasingly popular. GPS/INS systems offer a high data rate, high accuracy position and orientation that can work in all environments, particularly those where satellite availability is restricted. In the paper integration algorithm of GPS and INS systems data for pedestrians in urban area is presented. For data integration an Extended Kalman Filter (EKF algorithm is proposed. Complementary characteristics of GPS and INS with EKF can overcome the problem of huge INS drifts, GPS outages, dense multipath effect and other individual problems associated with these sensors.

A Political Campaign Strategy and Campaign Theme : How to Win a Political Campaign

OpenAIRE

河村, 直幸; Kawamura, Naoyuki

2004-01-01

The aim of this research paper is to introduce a political campaign strategy. A political campaign should do on a scientific system and needs effective strategy. Before political campaign begin, a candidate and its campaigner needs to analyze election district and sample voter opinion. An election campaign needs campaign theme. The creation of campaign theme needs careful and elaborate planning. A style of campaign varies according to incumbent or challenger. The developing of an effective po...

Tracking magma volume recovery at okmok volcano using GPS and an unscented kalman filter

Science.gov (United States)

Fournier, T.; Freymueller, Jeffrey T.; Cervelli, Peter

2009-01-01

Changes beneath a volcano can be observed through position changes in a GPS network, but distinguishing the source of site motion is not always straightforward. The records of continuous GPS sites provide a favorable data set for tracking magma migration. Dense campaign observations usually provide a better spatial picture of the overall deformation field, at the expense of an episodic temporal record. Combining these observations provides the best of both worlds. A Kalman filter provides a means for integrating discrete and continuous measurements and for interpreting subtle signals. The unscented Kalman filter (UKF) is a nonlinear method for time-dependent observations. We demonstrate the application of this technique to deformation data by applying it to GPS data collected at Okmok volcano. Seven years of GPS observations at Okmok are analyzed using a Mogi source model and the UKF. The deformation source at Okmok is relatively stable at 2.5 km depth below sea level, located beneath the center of the caldera, which means the surface deformation is caused by changes in the strength of the source. During the 7 years of GPS observations more than 0.5 m of uplift has occurred, a majority of that during the time period January 2003 to July 2004. The total volume recovery at Okmok since the last eruption in 1997 is ??60-80%. The UKF allows us to solve simultaneously for the time-dependence of the source strength and for the location without a priori information about the source. ?? 2009 by the American Geophysical Union.

Calibrating coseismic coastal land-level changes during the 2014 Iquique (Mw=8.2) earthquake (northern Chile) with leveling, GPS and intertidal biota.

Science.gov (United States)

Jaramillo, Eduardo; Melnick, Daniel; Baez, Juan Carlos; Montecino, Henry; Lagos, Nelson A; Acuña, Emilio; Manzano, Mario; Camus, Patricio A

2017-01-01

The April 1st 2014 Iquique earthquake (MW 8.1) occurred along the northern Chile margin where the Nazca plate is subducted below the South American continent. The last great megathrust earthquake here, in 1877 of Mw ~8.8 opened a seismic gap, which was only partly closed by the 2014 earthquake. Prior to the earthquake in 2013, and shortly after it we compared data from leveled benchmarks, deployed campaign GPS instruments, continuous GPS stations and estimated sea levels using the upper vertical level of rocky shore benthic organisms including algae, barnacles, and mussels. Land-level changes estimated from mean elevations of benchmarks indicate subsidence along a ~100-km stretch of coast, ranging from 3 to 9 cm at Corazones (18°30'S) to between 30 and 50 cm at Pisagua (19°30'S). About 15 cm of uplift was measured along the southern part of the rupture at Chanabaya (20°50'S). Land-level changes obtained from benchmarks and campaign GPS were similar at most sites (mean difference 3.7±3.2 cm). Higher differences however, were found between benchmarks and continuous GPS (mean difference 8.5±3.6 cm), possibly because sites were not collocated and separated by several kilometers. Subsidence estimated from the upper limits of intertidal fauna at Pisagua ranged between 40 to 60 cm, in general agreement with benchmarks and GPS. At Chanavaya, the magnitude and sense of displacement of the upper marine limit was variable across species, possibly due to species-dependent differences in ecology. Among the studied species, measurements on lithothamnioid calcareous algae most closely matched those made with benchmarks and GPS. When properly calibrated, rocky shore benthic species may be used to accurately measure land-level changes along coasts affected by subduction earthquakes. Our calibration of those methods will improve their accuracy when applied to coasts lacking pre-earthquake data and in estimating deformation during pre-instrumental earthquakes.

Selected Problems of Determining the Course of Railway Routes by Use of GPS Network Solution

Science.gov (United States)

Koc, Władysław; Specht, Cezary

2011-09-01

The main problem related to railroad surveying design and its maintenance is the necessity to operate in local geodetic reference systems caused by the long rail sections with straight lines and curvatures of the running edge. Due to that reason the geodetic railroad classical surveying methods requires to divide all track for a short measurement section and that caused additional errors. Development of the Global Navigational Satellite Systems (GNSS) positioning methods operating in the standardized World Geodetic System (WGS-84) allowed verification of capability of utilization GPS measurements for railroad surveying. It can be stated that implemented satellite measurement techniques opens a whole new perspective on applied research and enables very precise determination of data for railway line determining, modernization and design. The research works focused on implementation GNSS multi-receivers measurement positioning platform for projecting and stock-taking working based on polish active geodesic network ASG-EUPOS, as a reference frame. In order to eliminate the influence of random measurement errors and to obtain the coordinates representing the actual shape of the track few campaigns were realized in 2009 and 2010. Leica GPS Total station system 1200 SmartRover (with ATX1230 GG antennas) receivers were located in the diameter of the measurement platform. Polish Active Geodetic Network ASG-EUPOS was used as a reference network transmitted Real Time Kinematic Positioning Service according to RTCM 3.1 standard. Optimum time period were selected for GNSS campaign and testing area was chosen without large obstructions. The article presents some surveying results of the measurement campaigns and also discusses the accuracy of the course determination. Analyzes and implementation of results in railroad design process are also discussed.

Advanced Corrections for InSAR Using GPS and Numerical Weather Models

Science.gov (United States)

Cossu, F.; Foster, J. H.; Amelung, F.; Varugu, B. K.; Businger, S.; Cherubini, T.

2017-12-01

We present results from an investigation into the application of numerical weather models for generating tropospheric correction fields for Interferometric Synthetic Aperture Radar (InSAR). We apply the technique to data acquired from a UAVSAR campaign as well as from the CosmoSkyMed satellites. The complex spatial and temporal changes in the atmospheric propagation delay of the radar signal remain the single biggest factor limiting InSAR's potential for hazard monitoring and mitigation. A new generation of InSAR systems is being built and launched, and optimizing the science and hazard applications of these systems requires advanced methodologies to mitigate tropospheric noise. We use the Weather Research and Forecasting (WRF) model to generate a 900 m spatial resolution atmospheric models covering the Big Island of Hawaii and an even higher, 300 m resolution grid over the Mauna Loa and Kilauea volcanoes. By comparing a range of approaches, from the simplest, using reanalyses based on typically available meteorological observations, through to the "kitchen-sink" approach of assimilating all relevant data sets into our custom analyses, we examine the impact of the additional data sets on the atmospheric models and their effectiveness in correcting InSAR data. We focus particularly on the assimilation of information from the more than 60 GPS sites in the island. We ingest zenith tropospheric delay estimates from these sites directly into the WRF analyses, and also perform double-difference tomography using the phase residuals from the GPS processing to robustly incorporate heterogeneous information from the GPS data into the atmospheric models. We assess our performance through comparisons of our atmospheric models with external observations not ingested into the model, and through the effectiveness of the derived phase screens in reducing InSAR variance. Comparison of the InSAR data, our atmospheric analyses, and assessments of the active local and mesoscale

GPS Measurements for Detecting Aseismic Creeping in the Ismetpasa Region of North Anatolian Fault Zone, Turkey

Science.gov (United States)

Ozener, H.; Dogru, A.; Turgut, B.; Yilmaz, O.; Halicioglu, K.; Sabuncu, A.

2010-12-01

In 1972, a six point-network was established by General Directorate of Mapping in Gerede-Ismetpasa. This region is relatively quiet segment of western NAF which is creeping along steadily. This network was surveyed by terrestrial techniques in 1972 and 1973. The Ismetpasa Network was re-measured in 1982 and in 1992 by the Geodesy Working Group of Istanbul Technical University. Although the same network (with five points) was observed in 2002 and 2007 by Zonguldak Karaelmas University applying GPS technique, with 1-hour site occupation, the characteristics of movement has not been detected implicitly. This type of movement still raises a question about the accumulation of tectonic movements in the region. Geodesy Department of Kandilli Observatory and Earthquake Research Institute (KOERI) of Bogazici University has been re-surveyed the network by campaign-based static GPS surveying (10-hour site occupation) since 2005. The GPS velocities data coming from geodynamic GPS networks of the crustal deformation studies and the analysis of repeated geodetic observations give us significant information about the elastic deformation. Therefore, data gathered in this study is processed using GAMIT/GLOBK software and analyzed together with previously collected data to obtain velocity field and strain accumulation in the study area.

Gps monitoring of the la valette landslide (french alps) with two mono-frequency receivers

Science.gov (United States)

Squarzoni, C.; Delacourt, C.; Allemand, P.

2003-04-01

In the last years, the Global Positioning System techniques have been more and more employed in landslide monitoring. Here we present an application of the GPS techniques on the La Valette landslide, located in the Ubaye Valley in the southern French Alps. This complex landslide is composed by an upper part affected essentially by rotational mechanism, a central part with a generally translational movement and a lower part, occasionally transforming in mud flow in coincidence with strong rainfall events. Displacement rates are in average of a few centimetres per month and can reach one centimetre per day during spring. GPS data presented in this study have been acquired with a couple of mono-frequency GPS receivers Magellan ProMARK X-CM associated with multipath-resistant antennas and processed with the Magellan post-processing software MSTAR. Nine points have been set in the whole zone, seven of them in the moving area, one in a stable area near the landslide and one on the facing slope, used as reference point. For each measure, one GPS receiver is placed on the base point and the second one is placed on each monitored point for one-hour sessions. The baseline between base and monitored point ranges from 480 and 1660 m. Nine campaigns of measure have been made between October 2000 and October 2002, to follow the evolution of the surface displacements. The GPS results have been compared with the distance-meter measurements achieved on the same site by RTM Service (Restauration des Terrains de Montagne). The velocities obtained by the two methods are similar. The advantage of the GPS technique is the obtention of the real 3D displacement vector. These measurements have been combined with SAR interferometric data in order to derive a 3D map of the deformation.

Geomagnetic storm effects on GPS based navigation

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P. V. S. Rama Rao

2009-05-01

Full Text Available The energetic events on the sun, solar wind and subsequent effects on the Earth's geomagnetic field and upper atmosphere (ionosphere comprise space weather. Modern navigation systems that use radio-wave signals, reflecting from or propagating through the ionosphere as a means of determining range or distance, are vulnerable to a variety of effects that can degrade the performance of the navigational systems. In particular, the Global Positioning System (GPS that uses a constellation of earth orbiting satellites are affected due to the space weather phenomena.

Studies made during two successive geomagnetic storms that occurred during the period from 8 to 12 November 2004, have clearly revealed the adverse affects on the GPS range delay as inferred from the Total Electron Content (TEC measurements made from a chain of seven dual frequency GPS receivers installed in the Indian sector. Significant increases in TEC at the Equatorial Ionization anomaly crest region are observed, resulting in increased range delay during the periods of the storm activity. Further, the storm time rapid changes occurring in TEC resulted in a number of phase slips in the GPS signal compared to those on quiet days. These phase slips often result in the loss of lock of the GPS receivers, similar to those that occur during strong(>10 dB L-band scintillation events, adversely affecting the GPS based navigation.

Vocanic Deformations During Repose Interval Revealed by GPS Measurements, Batur Volcano, Indonesia

Science.gov (United States)

Nishimae, K.; Fujii, N.; Kimata, F.; Murase, M.; Suganda, O. K.; Abidin, H. Z.

2005-12-01

Batur volcano is located north west of Bali Island in Indonesia.This volcano has two calderas with more than 10 km in diameter. Recent eruptions with lava flow occurred in 1963 and 1974. No effusion of lava has been observed since 1990, although steam explosions occurred August 1994, November 1997 and June 1998.This suggests that magmatic activity of this volcano would keep its high level since 1994.GPS observation network of this volcano has been kept by Institute Technology of Bandung (ITB) and Volcano Survey of Indonesia (VSI).The network was consisted of 10 observation points at the beginning in 1999, and now it becomes 23 observation points. We have made GPS campaign observations about five times from 2003 to 2005. Each campaign observation consisted of a couple of days of measurements for each observation point. In order to keep the quality of data as high as possible, observations have been made at least 12 hours of continuous data for each point. In this report, results of two campaign observations (December 2004 and July 2005) are used for the analysis. The data thus obtained are fitted to the Mogi source (i.e. a point source model) to locate the depth and amount of volume changes for 7 months. Location of the Mogi source was obtained about 4km southeast of the summit of central cone, and 3km depth with deflation volume change of 1.3_~106 m3 for about 7months. For the period from 1999 to 2004, estimated volume change suggests a continuous deflation throughout this period, although the reliability of data was not so high. Continuous deflations might be likely after the last effusive eruption in 1974, would suggest that shallow part of magma beneath the central cone would probably be drained down to further deep, or shrinkage of magma associated with the cooling or solidification. Further data are obviously needed to discriminate the mechanisms of the deformation process during the repose period in this volcano.

Evaluation of a brief anti-stigma campaign in Cambridge: do short-term campaigns work?

Science.gov (United States)

Evans-Lacko, Sara; London, Jillian; Little, Kirsty; Henderson, Claire; Thornicroft, Graham

2010-06-14

In view of the high costs of mass-media campaigns, it is important to understand whether it is possible for a media campaign to have significant population effects over a short period of time. This paper explores this question specifically in reference to stigma and discrimination against people with mental health problems using the Time to Change Cambridge anti-stigma campaign as an example. 410 face-to-face interviews were performed pre, during and post campaign activity to assess campaign awareness and mental health-related knowledge, attitudes and behaviours. Although campaign awareness was not sustained following campaign activity, significant and sustained shifts occurred for mental health-related knowledge items. Specifically, there was a 24% (p mental health problem, I know what advice to give them to get professional help, following the campaign. Additionally, for the statement: Medication can be an effective treatment for people with mental health problems, there was a 10% rise (p = 0.05) in the proportion of interviewees responding 'agree' or 'strongly agree' following the campaign. These changes, however, were not evident for attitudinal or behaviour related questions. Although these results only reflect the impact of one small scale campaign, these preliminary findings suggest several considerations for mass-media campaign development and evaluation strategies such as: (1) Aiming to influence outcomes pertaining to knowledge in the short term; (2) Planning realistic and targeted outcomes over the short, medium and long term during sustained campaigns; and (3) Monitoring indirect campaign effects such as social discourse or other social networking/contact in the evaluation.

Accuracy of a 10 Hz GPS Unit in Measuring Shuttle Velocity Performed at Different Speeds and Distances (5 – 20 M

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Beato Marco

2016-12-01

Full Text Available The aim of this study was to validate the accuracy of a 10 Hz GPS device (STATSports, Ireland by comparing the instantaneous values of velocity determined with this device with those determined by kinematic (video analysis (25 Hz. Ten male soccer players were required to perform shuttle runs (with 180° change of direction at three velocities (slow: 2.2 m·s-1; moderate: 3.2 m·s-1; high: maximal over four distances: 5, 10, 15 and 20 m. The experiments were video-recorded; the “point by point” values of speed recorded by the GPS device were manually downloaded and analysed in the same way as the “frame by frame” values of horizontal speed as obtained by video analysis. The obtained results indicated that shuttle distance was smaller in GPS than video analysis (p < 0.01. Shuttle velocity (shuttle distance/shuttle time was thus smaller in GPS than in video analysis (p < 0.001; the percentage difference (bias, % in shuttle velocity between methods was found to decrease with the distance covered (5 m: 9 ± 6%; 20 m: 3 ± 3%. The instantaneous values of speed were averaged; from these data and from data of shuttle time, the distance covered was recalculated; the error (criterion distance-recalculated distance was negligible for video data (0.04 ± 0.28 m whereas GPS data underestimated criterion distance (0.31 ± 0.55 m. In conclusion, the inaccuracy of this GPS unit in determining shuttle speed can be attributed to inaccuracy in determining the shuttle distance.

Two laboratory methods for the calibration of GPS speed meters

International Nuclear Information System (INIS)

Bai, Yin; Sun, Qiao; Du, Lei; Yu, Mei; Bai, Jie

2015-01-01

The set-ups of two calibration systems are presented to investigate calibration methods of GPS speed meters. The GPS speed meter calibrated is a special type of high accuracy speed meter for vehicles which uses Doppler demodulation of GPS signals to calculate the measured speed of a moving target. Three experiments are performed: including simulated calibration, field-test signal replay calibration, and in-field test comparison with an optical speed meter. The experiments are conducted at specific speeds in the range of 40–180 km h −1 with the same GPS speed meter as the device under calibration. The evaluation of measurement results validates both methods for calibrating GPS speed meters. The relative deviations between the measurement results of the GPS-based high accuracy speed meter and those of the optical speed meter are analyzed, and the equivalent uncertainty of the comparison is evaluated. The comparison results justify the utilization of GPS speed meters as reference equipment if no fewer than seven satellites are available. This study contributes to the widespread use of GPS-based high accuracy speed meters as legal reference equipment in traffic speed metrology. (paper)

Effects of Reentry Plasma Sheath on GPS Patch Antenna Polarization Property

Directory of Open Access Journals (Sweden)

L. Zhao

2013-01-01

Full Text Available A plasma sheath enveloping a reentry vehicle would affect performances of on-board antenna greatly, especially the navigation antennas. This paper studies the effects of reentry plasma sheath on a GPS right-hand circularly polarized (RHCP patch antenna polarization property during a typical reentry process. Utilizing the algorithm of finite integration technique, the polarization characteristic of a GPS antenna coated by a plasma sheath is obtained. Results show that the GPS RHCP patch antenna radiation pattern distortions as well as polarization deteriorations exist during the entire reentry process, and the worst polarization mismatch loss between a GPS antenna and RHCP GPS signal is nearly 3 dB. This paper also indicates that measures should be taken to alleviate the plasma sheath for maintaining the GPS communication during the reentry process.

Software Defined GPS Receiver for International Space Station

Science.gov (United States)

Duncan, Courtney B.; Robison, David E.; Koelewyn, Cynthia Lee

2011-01-01

JPL is providing a software defined radio (SDR) that will fly on the International Space Station (ISS) as part of the CoNNeCT project under NASA's SCaN program. The SDR consists of several modules including a Baseband Processor Module (BPM) and a GPS Module (GPSM). The BPM executes applications (waveforms) consisting of software components for the embedded SPARC processor and logic for two Virtex II Field Programmable Gate Arrays (FPGAs) that operate on data received from the GPSM. GPS waveforms on the SDR are enabled by an L-Band antenna, low noise amplifier (LNA), and the GPSM that performs quadrature downconversion at L1, L2, and L5. The GPS waveform for the JPL SDR will acquire and track L1 C/A, L2C, and L5 GPS signals from a CoNNeCT platform on ISS, providing the best GPS-based positioning of ISS achieved to date, the first use of multiple frequency GPS on ISS, and potentially the first L5 signal tracking from space. The system will also enable various radiometric investigations on ISS such as local multipath or ISS dynamic behavior characterization. In following the software-defined model, this work will create a highly portable GPS software and firmware package that can be adapted to another platform with the necessary processor and FPGA capability. This paper also describes ISS applications for the JPL CoNNeCT SDR GPS waveform, possibilities for future global navigation satellite system (GNSS) tracking development, and the applicability of the waveform components to other space navigation applications.

Evaluation of mobile micro-sensing devices for GPS-based personal exposure monitoring of heat and particulate matter - a matter of context

Science.gov (United States)

Ueberham, Maximilian; Schlink, Uwe; Weiland, Ulrike

2017-04-01

The application of mobile micro-sensing devices (MSDs) for human health and personal exposure monitoring (PEM) is an emerging topic of interest in urban air quality research. In the context of climate change, urban population growth and related anthropogenic activities, an increase is expected for the intensity of citizens' exposure to heat and particulate matter (PM). Therefore more focus on the small-scale perspective of spatio-temporal distribution of air quality parameters is important to complement fixed-monitoring site data. Mobile sensors for PEM are useful for both, the investigation of the local distribution of air quality and the personal exposure profiles of individuals moving within their activity spaces. An evaluation of MSDs' accuracy is crucial, before their sophisticated application in measurement campaigns. To detect variations of exposure at small scales, it is even more important to consider the accuracy of Global Positioning System (GPS) devices within different urban structure types (USTs). We present an assessment of the performance of GPS-based MSDs under indoor laboratory conditions and outdoor testing within different USTs. The aim was to evaluate the accuracy of several GPS devices and MSDs for heat and PM 2.5 in relation to reliable standard sensing devices as part of a PhD-project. The performance parameters are summary measures (mean value, standard deviation), correlation (Pearson r), difference measures (mean bias error, mean absolute error, index of agreement) and Bland-Altman plots. The MSDs have been tested in a climate chamber under constant temperature and relative humidity. For temperature MSDs reaction time was tested because of its relevance to detect temperature variations during mobile measurements. For interpretation of the results we considered the MSDs design and technology (e.g. passive vs. active ventilation). GPS-devices have been tested within low/high dense urban residential areas and low/high dense urban green areas

High-precision coseismic displacement estimation with a single-frequency GPS receiver

Science.gov (United States)

Guo, Bofeng; Zhang, Xiaohong; Ren, Xiaodong; Li, Xingxing

2015-07-01

To improve the performance of Global Positioning System (GPS) in the earthquake/tsunami early warning and rapid response applications, minimizing the blind zone and increasing the stability and accuracy of both the rapid source and rupture inversion, the density of existing GPS networks must be increased in the areas at risk. For economic reasons, low-cost single-frequency receivers would be preferable to make the sparse dual-frequency GPS networks denser. When using single-frequency GPS receivers, the main problem that must be solved is the ionospheric delay, which is a critical factor when determining accurate coseismic displacements. In this study, we introduce a modified Satellite-specific Epoch-differenced Ionospheric Delay (MSEID) model to compensate for the effect of ionospheric error on single-frequency GPS receivers. In the MSEID model, the time-differenced ionospheric delays observed from a regional dual-frequency GPS network to a common satellite are fitted to a plane rather than part of a sphere, and the parameters of this plane are determined by using the coordinates of the stations. When the parameters are known, time-differenced ionospheric delays for a single-frequency GPS receiver could be derived from the observations of those dual-frequency receivers. Using these ionospheric delay corrections, coseismic displacements of a single-frequency GPS receiver can be accurately calculated based on time-differenced carrier-phase measurements in real time. The performance of the proposed approach is validated using 5 Hz GPS data collected during the 2012 Nicoya Peninsula Earthquake (Mw 7.6, 2012 September 5) in Costa Rica. This shows that the proposed approach improves the accuracy of the displacement of a single-frequency GPS station, and coseismic displacements with an accuracy of a few centimetres are achieved over a 10-min interval.

Evaluation of a brief anti-stigma campaign in Cambridge: do short-term campaigns work?

Directory of Open Access Journals (Sweden)

Henderson Claire

2010-06-01

Full Text Available Abstract Background In view of the high costs of mass-media campaigns, it is important to understand whether it is possible for a media campaign to have significant population effects over a short period of time. This paper explores this question specifically in reference to stigma and discrimination against people with mental health problems using the Time to Change Cambridge anti-stigma campaign as an example. Methods 410 face-to-face interviews were performed pre, during and post campaign activity to assess campaign awareness and mental health-related knowledge, attitudes and behaviours. Results Although campaign awareness was not sustained following campaign activity, significant and sustained shifts occurred for mental health-related knowledge items. Specifically, there was a 24% (p If a friend had a mental health problem, I know what advice to give them to get professional help, following the campaign. Additionally, for the statement: Medication can be an effective treatment for people with mental health problems, there was a 10% rise (p = 0.05 in the proportion of interviewees responding 'agree' or 'strongly agree' following the campaign. These changes, however, were not evident for attitudinal or behaviour related questions. Conclusions Although these results only reflect the impact of one small scale campaign, these preliminary findings suggest several considerations for mass-media campaign development and evaluation strategies such as: (1 Aiming to influence outcomes pertaining to knowledge in the short term; (2 Planning realistic and targeted outcomes over the short, medium and long term during sustained campaigns; and (3 Monitoring indirect campaign effects such as social discourse or other social networking/contact in the evaluation.

Performance evaluation of ionospheric time delay forecasting models using GPS observations at a low-latitude station

Science.gov (United States)

Sivavaraprasad, G.; Venkata Ratnam, D.

2017-07-01

Ionospheric delay is one of the major atmospheric effects on the performance of satellite-based radio navigation systems. It limits the accuracy and availability of Global Positioning System (GPS) measurements, related to critical societal and safety applications. The temporal and spatial gradients of ionospheric total electron content (TEC) are driven by several unknown priori geophysical conditions and solar-terrestrial phenomena. Thereby, the prediction of ionospheric delay is challenging especially over Indian sub-continent. Therefore, an appropriate short/long-term ionospheric delay forecasting model is necessary. Hence, the intent of this paper is to forecast ionospheric delays by considering day to day, monthly and seasonal ionospheric TEC variations. GPS-TEC data (January 2013-December 2013) is extracted from a multi frequency GPS receiver established at K L University, Vaddeswaram, Guntur station (geographic: 16.37°N, 80.37°E; geomagnetic: 7.44°N, 153.75°E), India. An evaluation, in terms of forecasting capabilities, of three ionospheric time delay models - an Auto Regressive Moving Average (ARMA) model, Auto Regressive Integrated Moving Average (ARIMA) model, and a Holt-Winter's model is presented. The performances of these models are evaluated through error measurement analysis during both geomagnetic quiet and disturbed days. It is found that, ARMA model is effectively forecasting the ionospheric delay with an accuracy of 82-94%, which is 10% more superior to ARIMA and Holt-Winter's models. Moreover, the modeled VTEC derived from International Reference Ionosphere, IRI (IRI-2012) model and new global TEC model, Neustrelitz TEC Model (NTCM-GL) have compared with forecasted VTEC values of ARMA, ARIMA and Holt-Winter's models during geomagnetic quiet days. The forecast results are indicating that ARMA model would be useful to set up an early warning system for ionospheric disturbances at low latitude regions.

Data Integration from GPS and Inertial Navigation Systems for Pedestrians in Urban Area

OpenAIRE

Krzysztof Bikonis; Jerzy Demkowicz

2013-01-01

The GPS system is widely used in navigation and the GPS receiver can offer long-term stable absolute positioning information. The overall system performance depends largely on the signal environments. The position obtained from GPS is often degraded due to obstruction and multipath effect caused by buildings, city infrastructure and vegetation, whereas, the current performance achieved by inertial navigation systems (INS) is still relatively poor due to the large inertial sensor errors. The c...

Precise levelling campaigns at Olkiluoto in 2012-2013

International Nuclear Information System (INIS)

Saaranen, V.; Rouhiainen, P.

2014-08-01

In order to research vertical bedrock deformations in the Olkiluoto area, Posiva Oy and the Finnish Geodetic Institute began monitoring with precise levelling in 2003. At the moment, the measuring plan includes a loop between the GPS stations around the island, a levelling line from the island to the mainland, levelling loops over the ONKALO, the characterization facility for the final disposal of spent nuclear fuel, and VLJ, the low and intermediate level waste repository. The levelling to the mainland has been performed every fourth year and the levelling of the GPS stations every second year. The micro loops (ONKALO and VLJ) have been measured annually. In this report, we present the Olkiluoto levelling observations, performed in 2012 and 2013. Local deformations have been analysed by comparing the height differences for different years. In the Olkiluoto strait area, the height changes from 2011 to 2012 were within ± 0.1 mm. In the GPS station loop, in 2011-2013, the height of benchmark (BM) GPS3 changed + 0.69 mm. It is the only benchmark, which height has changed more than one millimetre from the year 2003. Second largest deformation happened at GPS1. Its height changed - 0.49 mm from 2011 to 2013. In the ONKALO loop, largest height change, from 2011 to 2012 was - 0.37 mm. From 2012 to 2013, the largest height changes was - 0.4 mm. In the VLJ loop, the most active deformation is related to the control benchmarks of GPS9. In 2012, these benchmarks were 0.6 mm lower level than 2011. From 2012 to 2013, both benchmarks rebounded so that deformation from 2011 to 2013 is - 0.38 mm. The other benchmarks have deformation within ± 0.11 mm, from 2011 to 2013. In 2011, a new GPS station GPS16 was established. The GPS station has three control benchmarks on bedrock and one benchmark is part of a pillar. The height of the control benchmark fastened to pillar changed one millimetre, from 2011 to 2013, relative to the control benchmarks on bedrock. (orig.)

Ionospheric Scintillation Effects on GPS

Science.gov (United States)

Steenburgh, R. A.; Smithtro, C.; Groves, K.

2007-12-01

. Ionospheric scintillation of Global Positioning System (GPS) signals threatens navigation and military operations by degrading performance or making GPS unavailable. Scintillation is particularly active, although not limited to, a belt encircling the earth within 20 degrees of the geomagnetic equator. As GPS applications and users increases, so does the potential for detrimental impacts from scintillation. We examined amplitude scintillation data spanning seven years from Ascension Island, U.K.; Ancon, Peru; and Antofagasta, Chile in the Atlantic/Americas longitudinal sector at as well as data from Parepare, Indonesia; Marak Parak, Malaysia; Pontianak, Indonesia; Guam; and Diego Garcia, U.K.; in the Pacific longitudinal sector. From these data, we calculate percent probability of occurrence of scintillation at various intensities described by the S4 index. Additionally, we determine Dilution of Precision at one minute resolution. We examine diurnal, seasonal and solar cycle characteristics and make spatial comparisons. In general, activity was greatest during the equinoxes and solar maximum, although scintillation at Antofagasta, Chile was higher during 1998 rather than at solar maximum.

Mapping the Coastline Limits of the Mexican State Sinaloa Using GPS

Science.gov (United States)

Vazquez, G. E.

2007-12-01

This research work presents the delimitation of the coastline limits of Sinaloa (one of the richest states of northwestern Mexico). In order to achieve this big task, it was required to use GPS (Global Positioning System) together with leveling spirit measurements. Based on the appropriate selection of the cited measurement techniques, the objective was to map the Sinaloa's state coastline to have the cartography of approximate 1600 km of littoral. The GPS measurements were performed and referred with respect to a GPS network located across the state. This GPS network consists of at least one first-order-site at each of the sixteen counties that constitute the state, and three to four second-order-sites of the ten counties of the state surrounded by sea. The leveling spirit measurements were referred to local benchmarks pre-established by the Mexican agency SEMARNAT (SEcretaría Del Medio Ambiente y Recursos NATurales). Within the main specifications of the GPS measurements and equipment, we used geodetic-dual-frequency GPS receivers in kinematic mode for both base stations (first and second order sites of the GPS state network) and rover stations (points forming the state littoral) with 5-sec log-rate interval and 10 deg cut-off angle. The GPS data processing was performed using the commercial software Trimble Geomatics Office (TGO) with Double Differences (DD) in post-processing mode. To this point, the field measurements had been totally covered including the cartography (scale 1:1000) and this includes the specifications and appropriate labeling according to the Mexican norm NOM-146-SEMARNAT-2005.

Nonlinear Filtering with IMM Algorithm for Ultra-Tight GPS/INS Integration

Directory of Open Access Journals (Sweden)

Dah-Jing Jwo

2013-05-01

Full Text Available Abstract This paper conducts a performance evaluation for the ultra-tight integration of a Global positioning system (GPS and an inertial navigation system (INS, using nonlinear filtering approaches with an interacting multiple model (IMM algorithm. An ultra-tight GPS/INS architecture involves the integration of in-phase and quadrature components from the correlator of a GPS receiver with INS data. An unscented Kalman filter (UKF, which employs a set of sigma points by deterministic sampling, avoids the error caused by linearization as in an extended Kalman filter (EKF. Based on the filter structural adaptation for describing various dynamic behaviours, the IMM nonlinear filtering provides an alternative for designing the adaptive filter in the ultra-tight GPS/INS integration. The use of IMM enables tuning of an appropriate value for the process of noise covariance so as to maintain good estimation accuracy and tracking capability. Two examples are provided to illustrate the effectiveness of the design and demonstrate the effective improvement in navigation estimation accuracy. A performance comparison among various filtering methods for ultra-tight integration of GPS and INS is also presented. The IMM based nonlinear filtering approach demonstrates the effectiveness of the algorithm for improved positioning performance.

Multiple Interference Cancellation Performance for GPS Receivers with Dual-Polarized Antenna Arrays

Directory of Open Access Journals (Sweden)

Moeness G. Amin

2008-11-01

Full Text Available This paper examines the interference cancellation performance in global positioning system (GPS receivers equipped with dual-polarized antenna arrays. In dense jamming environment, different types of interferers can be mitigated by the dual-polarized antennas, either acting individually or in conjunction with other receiver antennas. We apply minimum variance distorntionless response (MVDR method to a uniform circular dual-polarized antenna array. The MVDR beamformer is constructed for each satellite. Analysis of the eigenstructures of the covariance matrix and the corresponding weight vector polarization characteristics are provided. Depending on the number of jammers and jammer polarizations, the array chooses to expend its degrees of freedom to counter the jammer polarization or/and use phase coherence to form jammer spatial nulls. Results of interference cancellations demonstrate that applying multiple MVDR beamformers, each for one satellite, has a superior cancellation performance compared to using only one MVDR beamformer for all satellites in the field of view.

Challenges and advantages of using GPS data in outdoor advertisement

OpenAIRE

Hecker, Dirk; Körner, Christine; May, Michael

2011-01-01

A growing number of companies use mobility data in their day-to-day business. Especially in the area of outdoor advertising, GPS devices have been successfully applied in order to measure poster performance in recent years. Based on personal mobility traces, the quality and precision of performance measures has increased significantly. However, the usage of GPS technology poses several challenges when applied to critical business processes. We will present several challenges and solutions whi...

Analysis of Regional GPS Networks in Eastern Ontario

Science.gov (United States)

Samadi Alinia, H.; Tiampo, K. F.

2014-12-01

Although stable, intraplate region of eastern Canada is considered low rate deformation area in the North American plate, the retreat of large ice sheets during deglaciation in the last 20 ka has resulted in horizontal and vertical deformation of the Earth's in eastern Ontario. Present-day glacial isostatic adjustment (GIA) uplift rates approach 10 mm/yr or more at Hudson Bay and decrease with distance southeastward. Current GIA models forecast that the hinge line between uplift to the northwest and subsidence to the southeast lies somewhere near the Saint Lawrence valley in eastern Canada [Tushingham and Peltier, 1991; Peltier, 2002]. Employing continuous Global Positioning System (cGPS) observations and high precision tools for processing and then analyzing each component of derived time series are important tools to monitor the associated regional crustal deformation with good accuracies. Here we describe the analysis of coordinate time series of cGPS stations scattered sparsely throughout southeastern Ontario and between Ottawa and the east coast of Hudson Bay. Here, the two most reliable local networks, each including 4 to 6 reference stations, were selected for analysis. Data for period of approximately five years, 2008-2012.9, was processed with Bernese 5.0 over several campaigns. Individual cGPS coordinate time series were generated for each station and basic parameters, such as mean, variance and repeatability, were estimated. The time series are corrected with respect to the rigid plate motion and seasonal variations and advanced time series analysis techniques, including spectral analysis and principal component analysis were implemented. Post-processing of the time series reproduces the general GIA spatial pattern. Results also show that the vertical velocities of all stations in the solution are consistent with the GIA model uplift rate and are consistent with other cGPS sites in eastern Canada and increases from north of lake of Ontario (approximately

Integrating GIS and GPS in environmental remediation oversight

International Nuclear Information System (INIS)

Kaletsky, K.; Earle, J.R.; Schneider, T.A.

1996-01-01

This paper presents findings on Ohio EPA Office of Federal Facilities Oversight's (OFFO) use of GIS and GPS for environmental remediation oversight at the U.S. Department of Energy's (DOE) Fernald Site. The Fernald site is a former uranium metal production facility within DOE's nuclear weapons complex. Significant uranium contamination of soil and groundwater is being remediated under state and federal regulations. OFFO uses GIS/GPS to enhance environmental monitoring and remediation oversight. These technologies are utilized within OFFO's environmental monitoring program for sample location and parameter selection, data interpretation and presentation. GPS is used to integrate sample data into OFFO's GIS and for permanently linking precise and accurate geographic data to samples and waste units. It is important to identify contamination geographically as all visual references (e.g., buildings, infrastructure) will be removed during remediation. Availability of the GIS allows OFFO to perform independent analysis and review of DOE contractor generated data, models, maps, and designs. This ability helps alleviate concerns associated with open-quotes black boxclose quotes models and data interpretation. OFFO's independent analysis has increased regulatory confidence and the efficiency of design reviews. GIS/GPS technology allows OFFO to record and present complex data in a visual format aiding in stakeholder education and awareness. Presented are OFFO's achievements within the aforementioned activities and some reasons learned in implementing the GIS/GPS program. OFFO's two years of GIS/GPS development have resulted in numerous lessons learned and ideas for increasing effectiveness through the use of GIS/GPS

GPS: Public Utility or Software Platform

Science.gov (United States)

2016-09-01

train for GPS loss, encourage use of GPS signal integrity monitors , develop in- vehicle GPS backups, and evaluate the range of radio...literature prevent the full quantification of exactly how vulnerable GPS is to service interruption. This thesis used constant comparison analysis to...criticality, resilience, and vulnerability. This methodology overcomes research limitations by using GPS system design, operations, and policies as

A Mobile GPS Application: Mosque Tracking with Prayer Time Synchronization

Science.gov (United States)

Hashim, Rathiah; Ikhmatiar, Mohammad Sibghotulloh; Surip, Miswan; Karmin, Masiri; Herawan, Tutut

Global Positioning System (GPS) is a popular technology applied in many areas and embedded in many devices, facilitating end-users to navigate effectively to user's intended destination via the best calculated route. The ability of GPS to track precisely according to coordinates of specific locations can be utilized to assist a Muslim traveler visiting or passing an unfamiliar place to find the nearest mosque in order to perform his prayer. However, not many techniques have been proposed for Mosque tracking. This paper presents the development of GPS technology in tracking the nearest mosque using mobile application software embedded with the prayer time's synchronization system on a mobile application. The prototype GPS system developed has been successfully incorporated with a map and several mosque locations.

Efficient GPS Position Determination Algorithms

National Research Council Canada - National Science Library

Nguyen, Thao Q

2007-01-01

... differential GPS algorithm for a network of users. The stand-alone user GPS algorithm is a direct, closed-form, and efficient new position determination algorithm that exploits the closed-form solution of the GPS trilateration equations and works...

GPS Estimates of Integrated Precipitable Water Aid Weather Forecasters

Science.gov (United States)

Moore, Angelyn W.; Gutman, Seth I.; Holub, Kirk; Bock, Yehuda; Danielson, David; Laber, Jayme; Small, Ivory

2013-01-01

Global Positioning System (GPS) meteorology provides enhanced density, low-latency (30-min resolution), integrated precipitable water (IPW) estimates to NOAA NWS (National Oceanic and Atmospheric Adminis tration Nat ional Weather Service) Weather Forecast Offices (WFOs) to provide improved model and satellite data verification capability and more accurate forecasts of extreme weather such as flooding. An early activity of this project was to increase the number of stations contributing to the NOAA Earth System Research Laboratory (ESRL) GPS meteorology observing network in Southern California by about 27 stations. Following this, the Los Angeles/Oxnard and San Diego WFOs began using the enhanced GPS-based IPW measurements provided by ESRL in the 2012 and 2013 monsoon seasons. Forecasters found GPS IPW to be an effective tool in evaluating model performance, and in monitoring monsoon development between weather model runs for improved flood forecasting. GPS stations are multi-purpose, and routine processing for position solutions also yields estimates of tropospheric zenith delays, which can be converted into mm-accuracy PWV (precipitable water vapor) using in situ pressure and temperature measurements, the basis for GPS meteorology. NOAA ESRL has implemented this concept with a nationwide distribution of more than 300 "GPSMet" stations providing IPW estimates at sub-hourly resolution currently used in operational weather models in the U.S.

A novel fusion methodology to bridge GPS outages for land vehicle positioning

International Nuclear Information System (INIS)

Chen, Wei; Li, Xu; Song, Xiang; Xu, Qimin; Li, Bin; Song, Xianghui

2015-01-01

Many intelligent transportation system applications require accurate, reliable, and continuous vehicle position information whether in open-sky environments or in Global Positioning System (GPS) denied environments. However, there remains a challenging task for land vehicles to achieve such positioning performance using low-cost sensors, especially microelectromechanical system (MEMS) sensors. In this paper, a novel and cost-effective fusion methodology to bridge GPS outages is proposed and applied in the Inertial Navigation System (INS)/GPS/ compass integrated positioning system. In the implementation of the proposed methodology, a key data preprocessing algorithm is first developed to eliminate the noise in inertial sensors in order to provide more accurate information for subsequent modeling. Then, a novel hybrid strategy incorporating the designed autoregressive model (AR model)-based forward estimator (ARFE) with Kalman filter (KF) is presented to predict the INS position errors during GPS outages. To verify the feasibility and effectiveness of the proposed methodology, real road tests with various scenarios were performed. The proposed methodology illustrates significant improvement in positioning accuracy during GPS outages. (paper)

Standardization of GPS data processing

International Nuclear Information System (INIS)

Park, Pil Ho

2001-06-01

A nationwide GPS network has been constructed with about 60 permanent GPS stations after late 1990s in Korea. For using the GPS in variety of application area like crustal deformation, positioning, or monitoring upper atmosphere, it is necessary to have ability to process the data precisely. Now Korea Astronomy Observatory has the precise GPS data processing technique in Korea because it is difficult to understand characteristics of the parameters we want to estimate, resolve the integer ambiguity, and analyze many errors. There are three reliable GPS data processing software in the world ; Bernese(University of Berne), GIPSY-OASIS(JPL), GAMIT(MIT). These software allow us to achieve millimeter accuracy in the horizontal position and about 1 cm accuracy vertically even for regional networks with a diameter of several thousand kilometers. But we established the standard of GPS data processing using Bernese as main tool and GIPSY O ASIS as side

GPS Position Time Series @ JPL

Science.gov (United States)

Owen, Susan; Moore, Angelyn; Kedar, Sharon; Liu, Zhen; Webb, Frank; Heflin, Mike; Desai, Shailen

2013-01-01

Different flavors of GPS time series analysis at JPL - Use same GPS Precise Point Positioning Analysis raw time series - Variations in time series analysis/post-processing driven by different users. center dot JPL Global Time Series/Velocities - researchers studying reference frame, combining with VLBI/SLR/DORIS center dot JPL/SOPAC Combined Time Series/Velocities - crustal deformation for tectonic, volcanic, ground water studies center dot ARIA Time Series/Coseismic Data Products - Hazard monitoring and response focused center dot ARIA data system designed to integrate GPS and InSAR - GPS tropospheric delay used for correcting InSAR - Caltech's GIANT time series analysis uses GPS to correct orbital errors in InSAR - Zhen Liu's talking tomorrow on InSAR Time Series analysis

Semantic Enrichment of GPS Trajectories

NARCIS (Netherlands)

de Graaff, V.; van Keulen, Maurice; de By, R.A.

2012-01-01

Semantic annotation of GPS trajectories helps us to recognize the interests of the creator of the GPS trajectories. Automating this trajectory annotation circumvents the requirement of additional user input. To annotate the GPS traces automatically, two types of automated input are required: 1) a

Applying GPS to enhance understanding of transport-related physical activity.

Science.gov (United States)

Duncan, Mitch J; Badland, Hannah M; Mummery, W Kerry

2009-09-01

The purpose of the paper is to review the utility of the global positioning system (GPS) in the study of health-related physical activity. The paper draws from existing literature to outline the current work performed using GPS to examine transport-related physical activity, with a focus on the relative utility of the approach when combined with geographic information system (GIS) and other data sources including accelerometers. The paper argues that GPS, especially when used in combination with GIS and accelerometery, offers great promise in objectively measuring and studying the relationship of numerous environmental attributes to human behaviour in terms of physical activity and transport-related activity. Limitations to the use of GPS for the purpose of monitoring health-related physical activity are presented, and recommendations for future avenues of research are discussed.

Sensing Human Activity: GPS Tracking

Science.gov (United States)

van der Spek, Stefan; van Schaick, Jeroen; de Bois, Peter; de Haan, Remco

2009-01-01

The enhancement of GPS technology enables the use of GPS devices not only as navigation and orientation tools, but also as instruments used to capture travelled routes: as sensors that measure activity on a city scale or the regional scale. TU Delft developed a process and database architecture for collecting data on pedestrian movement in three European city centres, Norwich, Rouen and Koblenz, and in another experiment for collecting activity data of 13 families in Almere (The Netherlands) for one week. The question posed in this paper is: what is the value of GPS as ‘sensor technology’ measuring activities of people? The conclusion is that GPS offers a widely useable instrument to collect invaluable spatial-temporal data on different scales and in different settings adding new layers of knowledge to urban studies, but the use of GPS-technology and deployment of GPS-devices still offers significant challenges for future research. PMID:22574061

Sensing Human Activity: GPS Tracking

Directory of Open Access Journals (Sweden)

Remco de Haan

2009-04-01

Full Text Available The enhancement of GPS technology enables the use of GPS devices not only as navigation and orientation tools, but also as instruments used to capture travelled routes: as sensors that measure activity on a city scale or the regional scale. TU Delft developed a process and database architecture for collecting data on pedestrian movement in three European city centres, Norwich, Rouen and Koblenz, and in another experiment for collecting activity data of 13 families in Almere (The Netherlands for one week. The question posed in this paper is: what is the value of GPS as ‘sensor technology’ measuring activities of people? The conclusion is that GPS offers a widely useable instrument to collect invaluable spatial-temporal data on different scales and in different settings adding new layers of knowledge to urban studies, but the use of GPS-technology and deployment of GPS-devices still offers significant challenges for future research.

GPS Satellite Simulation Facility

Data.gov (United States)

Federal Laboratory Consortium — The GPS satellite simulation facility consists of a GPS satellite simulator controlled by either a Silicon Graphics Origin 2000 or PC depending upon unit under test...

Measurements of ionospheric TEC in the direction of GPS satellites and comparison with three ionospheric models

Directory of Open Access Journals (Sweden)

E. Zuccheretti

1997-06-01

Full Text Available The IEN Galileo Ferraris uses GPS for time and frequency synchronization. To obtain high performance it is important to reduce the error due to the ionospheric time-delay in GPS measurements. Evaluations of TEC in the direction of GPS satellites, obtained from three different ionospheric models, have been compared with corresponding measurements by GPS signal.

The SMS-GPS-Trip-Method

DEFF Research Database (Denmark)

Reinau, Kristian Hegner; Harder, Henrik; Weber, Michael

2015-01-01

This article presents a new method for collecting travel behavior data, based on a combination of GPS tracking and SMS technology, coined the SMS–GPS-Trip method. The state-of-the-art method for collecting data for activity based traffic models is a combination of travel diaries and GPS tracking...

Active landslide monitoring using remote sensing data, GPS measurements and cameras on board UAV

Science.gov (United States)

Nikolakopoulos, Konstantinos G.; Kavoura, Katerina; Depountis, Nikolaos; Argyropoulos, Nikolaos; Koukouvelas, Ioannis; Sabatakakis, Nikolaos

2015-10-01

An active landslide can be monitored using many different methods: Classical geotechnical measurements like inclinometer, topographical survey measurements with total stations or GPS and photogrammetric techniques using airphotos or high resolution satellite images. As the cost of the aerial photo campaign and the acquisition of very high resolution satellite data is quite expensive the use of cameras on board UAV could be an identical solution. Small UAVs (Unmanned Aerial Vehicles) have started their development as expensive toys but they currently became a very valuable tool in remote sensing monitoring of small areas. The purpose of this work is to demonstrate a cheap but effective solution for an active landslide monitoring. We present the first experimental results of the synergistic use of UAV, GPS measurements and remote sensing data. A six-rotor aircraft with a total weight of 6 kg carrying two small cameras has been used. Very accurate digital airphotos, high accuracy DSM, DGPS measurements and the data captured from the UAV are combined and the results are presented in the current study.

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.

Surface deformation analysis over Vrancea seismogenic area through radar and GPS geospatial data

Science.gov (United States)

Zoran, Maria A.; Savastru, Roxana S.; Savastru, Dan M.; Serban, Florin S.; Teleaga, Delia M.; Mateciuc, Doru N.

2017-10-01

Time series analysis of GPS (Global Positioning Systems) and InSAR (Interferometric Synthetic Aperture Radar) data are important tools for Earth's surface deformation assessment, which can result from a wide range of geological phenomena like as earthquakes, landslides or ground water level changes. The aim of this paper was to identify several types of earthquake precursors that might be observed from geospatial data in Vrancea seismogenic region in Romania. Continuous GPS Romanian network stations and few field campaigns data recorded between 2005-2012 years revealed a displacement of about 5 or 6 millimeters per year in horizontal direction relative motion, and a few millimeters per year in vertical direction. In order to assess possible deformations due to earthquakes and respectively for possible slow deformations, have been used also time series Sentinel 1 satellite data available for Vrancea zone during October 2014 till October 2016 to generate two types of interferograms (short-term and medium- term). During investigated period were not recorded medium or strong earthquakes, so interferograms over test area revealed small displacements on vertical direction (subsidence or uplifts) of 5-10 millimeters per year. Based on GPS continuous network data and satellite Sentinel 1 results, different possible tectonic scenarios were developed. The localization of horizontal and vertical motions, fault slip, and surface deformation of the continental blocks provides new information, in support of different geodynamic models for Vrancea tectonic active region in Romania and Europe.

Integrated INS/GPS Navigation from a Popular Perspective

Science.gov (United States)

Omerbashich, Mensur

2002-01-01

Inertial navigation, blended with other navigation aids, Global Positioning System (GPS) in particular, has gained significance due to enhanced navigation and inertial reference performance and dissimilarity for fault tolerance and anti-jamming. Relatively new concepts based upon using Differential GPS (DGPS) blended with Inertial (and visual) Navigation Sensors (INS) offer the possibility of low cost, autonomous aircraft landing. The FAA has decided to implement the system in a sophisticated form as a new standard navigation tool during this decade. There have been a number of new inertial sensor concepts in the recent past that emphasize increased accuracy of INS/GPS versus INS and reliability of navigation, as well as lower size and weight, and higher power, fault tolerance, and long life. The principles of GPS are not discussed; rather the attention is directed towards general concepts and comparative advantages. A short introduction to the problems faced in kinematics is presented. The intention is to relate the basic principles of kinematics to probably the most used navigation method in the future-INS/GPS. An example of the airborne INS is presented, with emphasis on how it works. The discussion of the error types and sources in navigation, and of the role of filters in optimal estimation of the errors then follows. The main question this paper is trying to answer is 'What are the benefits of the integration of INS and GPS and how is this, navigation concept of the future achieved in reality?' The main goal is to communicate the idea about what stands behind a modern navigation method.

Co-Seismic Effect of the 2011 Japan Earthquake on the Crustal Movement Observation Network of China

Directory of Open Access Journals (Sweden)

Shaomin Yang

2013-01-01

Full Text Available Great earthquakes introduce measurable co-seismic displacements over regions of hundreds and thousands of kilometers in width, which, if not accounted for, may significantly bias the long-term surface velocity field constrained by GPS observations performed during a period encompassing that event. Here, we first present an estimation of the far-field co-seismic off-sets associated with the 2011 Japan Mw 9.0 earthquake using GPS measurements from the Crustal Movement Observation Network of China (CMONOC in North China. The uncertainties of co-seismic off-set, either at cGPS stations or at campaign sites, are better than 5 - 6 mm on average. We compare three methods to constrain the co-seismic off-sets at the campaign sites in northeastern China 1 interpolating cGPS coseismic offsets, 2 estimating in terms of sparsely sampled time-series, and 3 predicting by using a well-constrained slip model. We show that the interpolation of cGPS co-seismic off-sets onto the campaign sites yield the best co-seismic off-set solution for these sites. The source model gives a consistent prediction based on finite dislocation in a layered spherical Earth, which agrees with the best prediction with discrepancies of 2 - 10 mm for 32 campaign sites. Thus, the co-seismic off-set model prediction is still a reasonable choice if a good coverage cGPS network is not available for a very active region like the Tibetan Plateau in which numerous campaign GPS sites were displaced by the recent large earthquakes.

Multi-Flight-Phase GPS Navigation Filter Applications to Terrestrial Vehicle Navigation and Positioning

Science.gov (United States)

Park, Young W.; Montez, Moises N.

1994-01-01

A candidate onboard space navigation filter demonstrated excellent performance (less than 8 meter level RMS semi-major axis accuracy) in performing orbit determination of a low-Earth orbit Explorer satellite using single-frequency real GPS data. This performance is significantly better than predicted by other simulation studies using dual-frequency GPS data. The study results revealed the significance of two new modeling approaches evaluated in the work. One approach introduces a single-frequency ionospheric correction through pseudo-range and phase range averaging implementation. The other approach demonstrates a precise axis-dependent characterization of dynamic sample space uncertainty to compute a more accurate Kalman filter gain. Additionally, this navigation filter demonstrates a flexibility to accommodate both perturbational dynamic and observational biases required for multi-flight phase and inhomogeneous application environments. This paper reviews the potential application of these methods and the filter structure to terrestrial vehicle and positioning applications. Both the single-frequency ionospheric correction method and the axis-dependent state noise modeling approach offer valuable contributions in cost and accuracy improvements for terrestrial GPS receivers. With a modular design approach to either 'plug-in' or 'unplug' various force models, this multi-flight phase navigation filter design structure also provides a versatile GPS navigation software engine for both atmospheric and exo-atmospheric navigation or positioning use, thereby streamlining the flight phase or application-dependent software requirements. Thus, a standardized GPS navigation software engine that can reduce the development and maintenance cost of commercial GPS receivers is now possible.

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

Science.gov (United States)

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

1997-01-01

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

Proof of concept for turbulence measurements with the RPAS SUMO during the BLLAST campaign

Science.gov (United States)

Båserud, Line; Reuder, Joachim; Jonassen, Marius O.; Kral, Stephan T.; Paskyabi, Mostafa B.; Lothon, Marie

2016-10-01

The micro-RPAS (remotely piloted aircraft system) SUMO (Small Unmanned Meteorological Observer) equipped with a five-hole-probe (5HP) system for turbulent flow measurements was operated in 49 flight missions during the BLLAST (Boundary-Layer Late Afternoon and Sunset Turbulence) field campaign in 2011. Based on data sets from these flights, we investigate the potential and limitations of airborne velocity variance and TKE (turbulent kinetic energy) estimations by an RPAS with a take-off weight below 1 kg. The integration of the turbulence probe in the SUMO system was still in an early prototype stage during this campaign, and therefore extensive post-processing of the data was required. In order to be able to calculate the three-dimensional wind vector, flow probe measurements were first synchronized with the autopilot's attitude and velocity data. Clearly visible oscillations were detected in the resulting vertical velocity, w, even after correcting for the aircraft motion. The oscillations in w were identified as the result of an internal time shift between the inertial measurement unit (IMU) and the GPS sensors, leading to insufficient motion correction, especially for the vertical wind component, causing large values of σw. Shifting the IMU 1-1.5 s forward in time with respect to the GPS yields a minimum for σw and maximum covariance between the IMU pitch angle and the GPS climb angle. The SUMO data show a good agreement to sonic anemometer data from a 60 m tower for σu, but show slightly higher values for σv and σw. Vertical TKE profiles, obtained from consecutive flight legs at different altitudes, show reasonable results, both with respect to the overall TKE level and the temporal variation. A thorough discussion of the methods used and the identified uncertainties and limitations of the system for turbulence measurements is included and should help the developers and users of other systems with similar problems.

Performance metrics for Inertial Confinement Fusion implosions: aspects of the technical framework for measuring progress in the National Ignition Campaign

International Nuclear Information System (INIS)

Spears, B.K.; Glenzer, S.; Edwards, M.J.; Brandon, S.; Clark, D.; Town, R.; Cerjan, C.; Dylla-Spears, R.; Mapoles, E.; Munro, D.; Salmonson, J.; Sepke, S.; Weber, S.; Hatchett, S.; Haan, S.; Springer, P.; Moses, E.; Mapoles, E.; Munro, D.; Salmonson, J.; Sepke, S.

2011-01-01

The National Ignition Campaign (NIC) uses non-igniting 'THD' capsules to study and optimize the hydrodynamic assembly of the fuel without burn. These capsules are designed to simultaneously reduce DT neutron yield and to maintain hydrodynamic similarity with the DT ignition capsule. We will discuss nominal THD performance and the associated experimental observables. We will show the results of large ensembles of numerical simulations of THD and DT implosions and their simulated diagnostic outputs. These simulations cover a broad range of both nominal and off nominal implosions. We will focus on the development of an experimental implosion performance metric called the experimental ignition threshold factor (ITFX). We will discuss the relationship between ITFX and other integrated performance metrics, including the ignition threshold factor (ITF), the generalized Lawson criterion (GLC), and the hot spot pressure (HSP). We will then consider the experimental results of the recent NIC THD campaign. We will show that we can observe the key quantities for producing a measured ITFX and for inferring the other performance metrics. We will discuss trends in the experimental data, improvement in ITFX, and briefly the upcoming tuning campaign aimed at taking the next steps in performance improvement on the path to ignition on NIF.

Performance metrics for Inertial Confinement Fusion implosions: aspects of the technical framework for measuring progress in the National Ignition Campaign

Energy Technology Data Exchange (ETDEWEB)

Spears, B K; Glenzer, S; Edwards, M J; Brandon, S; Clark, D; Town, R; Cerjan, C; Dylla-Spears, R; Mapoles, E; Munro, D; Salmonson, J; Sepke, S; Weber, S; Hatchett, S; Haan, S; Springer, P; Moses, E; Mapoles, E; Munro, D; Salmonson, J; Sepke, S

2011-12-16

The National Ignition Campaign (NIC) uses non-igniting 'THD' capsules to study and optimize the hydrodynamic assembly of the fuel without burn. These capsules are designed to simultaneously reduce DT neutron yield and to maintain hydrodynamic similarity with the DT ignition capsule. We will discuss nominal THD performance and the associated experimental observables. We will show the results of large ensembles of numerical simulations of THD and DT implosions and their simulated diagnostic outputs. These simulations cover a broad range of both nominal and off nominal implosions. We will focus on the development of an experimental implosion performance metric called the experimental ignition threshold factor (ITFX). We will discuss the relationship between ITFX and other integrated performance metrics, including the ignition threshold factor (ITF), the generalized Lawson criterion (GLC), and the hot spot pressure (HSP). We will then consider the experimental results of the recent NIC THD campaign. We will show that we can observe the key quantities for producing a measured ITFX and for inferring the other performance metrics. We will discuss trends in the experimental data, improvement in ITFX, and briefly the upcoming tuning campaign aimed at taking the next steps in performance improvement on the path to ignition on NIF.

Monitoring of Landslides using Repeated Kinematics GPS Observables in Sevketiye Town, Biga Peninsula, Çanakkale, NW Turkey

Science.gov (United States)

Cuneyt Erenoglu, Ramazan; Akcay, Ozgun; Karaca, Zeki; Erenoglu, Oya; Sengul Uluocak, Ebru; Yucel, Mehmet Ali

2014-05-01

Landslide is one of the most important natural events, and is also a result of earth's crust movements. Landslides generally result in the outward and downward movement of slope-forming materials consisting soil, rock, artificial fill and etc. Moreover, possible earthquakes are one of the main reasons of triggering landslides in active areas seismically. There have been many studies based on the Global Positioning System (GPS) observables to compute the three dimensional positioning of established sites, and to model landslides precisely. We can monitor landslide with GPS using continuous data collection or the type of campaign surveying. While continuous data collection provide a millimetre-level of accuracy, the accuracy decreases with the shorter sessions, e.g. campaign surveying, due to possible sources of error. The area, located west of the Çanakkale, has been studied to identify the landslide susceptibility and geology. Çanakkale, NW Turkey, is located on the territory of the Biga Peninsula and the Gallipoli Peninsula. The section of remaining at the west of the line from the Gulf of Edremit to the Gulf of Erdek is called Biga Peninsula, and it covers an area of approximately 10 thousand km². In the Biga Peninsula, the main morphological units are at the western, northern and southern of coastal plains, and on their behind the hills, plateaus and mountainous areas of the inland. But at the middle areas, it is often possible to find the tectonic depressions sandwiched between the masses plateau and mountainous. In general, moving down the slope of a rock, soil or debris can be defined as landslides that are ranks second in terms of caused losses after earthquakes in Turkey. Landslides, harm to urbanization as well as loss of lives and economic losses. Moreover they adversely affects to agricultural, forest areas and the quality of the rivers. For example, the gas pipeline connecting Turkey and Greece, which will provide gas to the Southern Europe passes

The performance of the remote analytical laboratory during the first fluorinel dissolution process campaign

International Nuclear Information System (INIS)

Lewis, L.C.; Henscheid, J.P.

1989-01-01

The Remote Analytical Laboratory at the Idaho Chemical Processing Plant was designed to provide analytical chemistry support to the irradiated fuel processing and associated waste processing operations. The facility was put into radioactive operation on July 7, 1986, and operated for more than a year during the first fluorinel fuel dissolution process campaign. The facility incorporated a number of innovative features and was equipped with state-of-the-art analytical instrumentation. The success of the facility is a direct function of how well the remote analytical equipment performed. The performance is discussed in this article

GPS tomography tests for DInSAR applications on Mt. Etna

Directory of Open Access Journals (Sweden)

Massimo Aranzulla

2015-07-01

Full Text Available Tropospheric artifacts of SAR images in a volcanic area like Mt. Etna cause ambiguity in the interpretation of deformations with such technique. It would be useful to measure the delay caused by tropospheric anomalies in synthetic aperture radar (SAR satellite signals (phase of the back-scattered radar wave that could be interpreted as deformation. From the delay estimated through the GPS data processing, the tropospheric tomography of electromagnetic waves refractivity, has been performed using the SIMULps12 software. The aim of this study was to perform software synthetic tests by using SIMULps12 applied to atmospheric tomography and to verify the influence of the different GPS geodetic network configurations on obtaining a reliable tomography. Three different anomalies of increasing complexity have been investigated in order to understand the representative parameters of a correct tomography, the best spatial resolution and the portions of space in which the tomography is reliable. The tests also focused on fixing/establishing the a-priori atmospheric model and the critical values of the main parameters involved in the tomographic inversion. To this end, we made a random choice of two days, necessary to define the tomographic problem. Three different network configurations with 15, 30 and 90 GPS receivers were studied. The results indicate that the well-resolved area of tomographic images increases with the number of GPS receivers not linearly, and that the actual GPS network of 42 receivers is capable of revealing/detecting the atmospheric anomalies.

Performance of NAA methods in an International Interlaboratory Reference Material Characterization Campaign

International Nuclear Information System (INIS)

Ihnat, M.

2000-01-01

An extensive database of analytical results from a recent biological matrix Reference Material Characterization Campaign permitted an intercomparison of the performances of various methods among each other and with 'true' best estimate concentration values established for these materials. Six different variants of neutron activation analysis (NAA) methods were employed including: instrumental neutron activation analysis, instrumental neutron activation analysis with acid digestion, neutron activation analysis with radiochemical separation, neutron capture prompt gamma activation analysis, epithermal instrumental neutron activation analysis, and neutron activation analysis with preconcentration. The precision and accuracy performance of NAA-based analytical methods are compared with three other major techniques, atomic absorption spectrometry (AAS), atomic emission spectrometry (AES) and mass spectrometry (MS) for 28 elements in 10 natural matrix materials. (author)

Development of automatic techniques for GPS data management

International Nuclear Information System (INIS)

Park, Pil Ho

2001-06-01

It is necessary for GPS center to establish automatization as effective management of GPS network including data gathering, data transformation, data backup, data sending to IGS (International GPS Service for geodynamics), and precise ephemerides gathering. The operating program of GPS center has been adopted at KCSC (Korea Cadastral Survey Corporation), NGI (National Geography Institute), MOMAF (Ministry of Maritime Affairs and Fisheries) without self-development of core technique. The automatic management of GPS network is consists of GPS data management and data processing. It is also fundamental technique, which should be accomplished by every GPS centers. Therefore, this study carried out analyzing of Japanese GPS center, which has accomplished automatization by module considering applicability for domestic GPS centers

GPS Time Synchronization in School-Network Cosmic Ray Detectors

Science.gov (United States)

Berns, H.-G.; Burnett, T. H.; Gran, R.; Wilkes, R. J.

2004-06-01

The QuarkNet DAQ card for school-network cosmic ray detectors provides a low-cost alternative to using standard particle and nuclear physics fast pulse electronics modules. The board, which can be produced at a cost of less than $500.00 (USD), produces trigger time and pulse edge time data for 2- to 4-fold coincidence levels via a universal RS232 serial port interface, usable with any PC. Individual detector stations, each consisting of four scintillation counter modules, front-end electronics, and a GPS receiver, produce a stream of data in form of ASCII text strings in identifiable set of formats for different functions. The card includes a low-cost GPS receiver module, which permits time-stamping event triggers to about 50 nanosecond accuracy in UTC between widely separated sites. The technique used for obtaining precise GPS time employs the 1PPS signal, which is not normally available to users of the commercial GPS module. We had the stock model slightly custom-modified to access this signal. The method for deriving time values was adapted from methods developed for the K2K long-baseline neutrino experiment. Performance of the low-cost GPS module used is compared to that of a more expensive unit with known quality.

GPS in Travel and Activity Surveys

DEFF Research Database (Denmark)

Nielsen, Thomas Alexander Sick; Hovgesen, Henrik Harder

2004-01-01

The use of GPS-positioning as a monitoring tool in travel and activity surveys opens up a range of possibilities. Using a personal GPS device, the locations and movements of respondents can be followed over a longer period of time. It will then be possible to analyse how the use of urban spaces...... are embedded in the wider context of activity patterns (work, school etc.). The general pattern of everyday itineraries, including route choice and time spent at different locations ?on the way? can also be analysed. If the personal GPS device is combined with an electronic questionnaire, for example...... area. The paper presents the possibilities in travel and activity surveys with GPS and electronic questionnaires. Demonstrative mapping of test data from passive GPS registration of Copenhagen respondents is presented. The different survey possibilities given a combination of GPS and PDA based...

IAE-adaptive Kalman filter for INS/GPS integrated navigation system

Institute of Scientific and Technical Information of China (English)

Bian Hongwei; Jin Zhihua; Tian Weifeng

2006-01-01

A marine INS/GPS adaptive navigation system is presented in this paper. GPS with two antenna providing vessel's altitude is selected as the auxiliary system fusing with INS to improve the performance of the hybrid system. The Kalman filter is the most frequently used algorithm in the integrated navigation system, which is capable of estimating INS errors online based on the measured errors between INS and GPS. The standard Kalman filter (SKF) assumes that the statistics of the noise on each sensor are given. As long as the noise distributions do not change, the Kalman filter will give the optimal estimation. However GPS receiver will be disturbed easily and thus temporally changing measurement noise will join into the outputs of GPS, which will lead to performance degradation of the Kalman filter. Many researchers introduce fuzzy logic control method into innovation-based adaptive estimation adaptive Kalman filtering (IAE-AKF) algorithm, and accordingly propose various adaptive Kalman filters. However how to design the fuzzy logic controller is a very complicated problem still without a convincing solution. A novel IAE-AKF is proposed herein, which is based on the maximum likelihood criterion for the proper computation of the filter innovation covariance and hence of the filter gain. The approach is direct and simple without having to establish fuzzy inference rules. After having deduced the proposed IAE-AKF algorithm theoretically in detail, the approach is tested by the simulation based on the system error model of the developed INS/GPS integrated marine navigation system. Simulation results show that the adaptive Kalman filter outperforms the SKF with higher accuracy, robustness and less computation. It is demonstrated that this proposed approach is a valid solution for the unknown changing measurement noise exited in the Kalman filter.

How does the workload and work activities of procedural GPs compare to non-procedural GPs?

Science.gov (United States)

Russell, Deborah J; McGrail, Matthew R

2017-08-01

To investigate patterns of Australian GP procedural activity and associations with: geographical remoteness and population size hours worked in hospitals and in total; and availability for on-call DESIGN AND PARTICIPANTS: National annual panel survey (Medicine in Australia: Balancing Employment and Life) of Australian GPs, 2011-2013. Self-reported geographical work location, hours worked in different settings, and on-call availability per usual week, were analysed against GP procedural activity in anaesthetics, obstetrics, surgery or emergency medicine. Analysis of 9301 survey responses from 4638 individual GPs revealed significantly increased odds of GP procedural activity in anaesthetics, obstetrics or emergency medicine as geographical remoteness increased and community population size decreased, albeit with plateauing of the effect-size from medium-sized (population 5000-15 000) rural communities. After adjusting for confounders, procedural GPs work more hospital and more total hours each week than non-procedural GPs. In 2011 this equated to GPs practising anaesthetics, obstetrics, surgery, and emergency medicine providing 8% (95%CI 0, 16), 13% (95%CI 8, 19), 8% (95%CI 2, 15) and 18% (95%CI 13, 23) more total hours each week, respectively. The extra hours are attributable to longer hours worked in hospital settings, with no reduction in private consultation hours. Procedural GPs also carry a significantly higher burden of on-call. The longer working hours and higher on-call demands experienced by rural and remote procedural GPs demand improved solutions, such as changes to service delivery models, so that long-term procedural GP careers are increasingly attractive to current and aspiring rural GPs. © 2016 National Rural Health Alliance Inc.

INFORMATION CAMPAIGNS – MEANS OF COMMUNICATION WITH CUSTOMERS

Directory of Open Access Journals (Sweden)

Claudia-Nicoleta Dobrescu

2013-12-01

Full Text Available Within a company’s activities, an important role is granted to the performance and implementation of information campaigns for the final consumers. The paper has the general objective to identify specific issues that constitute the premises for the preparation and conduct of such activities, and especially the expected results. The analysis is performed and based on a direct research among several companies, which operate in various fields, for the identification of a method of performance and implementation of information campaigns that are necessary for ensuring visibility on the reference market. The aim of the study was to identify the importance that the firms from Resita give to information campaigns addressed to a target audience. The study was carried from April to May 2013 on a sample of small, medium and large firms, which operate in trade, manufacturing and services. The questions and the discussions addressed to the public were meant to outline the specific aspects of the exact way in which the information campaigns were done for their clients, but also to underline the results obtained with the help of these campaigns.

Mapping large areas of radioactively contaminated land with a self adapted, handheld, GPS coupled, scintillation detector

International Nuclear Information System (INIS)

Paridaens, Johan

2008-01-01

In Belgium, during several decennia, a phosphate plant discharged radium chloride containing waste water into two small rivers. One of those is part of a hydrographically very complex ecosystem with lots of small tributaries and hundreds of hectares of flooding zones. Hence, the river banks and large parts of these flooding zones have become contaminated with radium, heavy metals and chlorides. During a foot campaign, using a home made portable data logging system, consisting of a commercial 2.5 kg NaI detector, a computer mouse sized GPS, and a small pocket PC, the radioactive contamination of about 600 ha of sometimes very rough terrain was measured and mapped. The resulting very detailed radium contamination maps shed a whole new light on the water flow patterns of the ecosystem. The apparatus can also be used for efficiently guiding sampling campaigns for investigating other types of contamination. The ground maps are also compared to existing maps from helicopter measurements, evaluating strengths and weaknesses from both methods

GPS Monitoring of Surface Change During and Following the Fortuitous Occurrence of the M(sub w) = 7.3 Landers Earthquake in our Network

Science.gov (United States)

Miller, M. Meghan

1998-01-01

Accomplishments: (1) Continues GPS monitoring of surface change during and following the fortuitous occurrence of the M(sub w) = 7.3 Landers earthquake in our network, in order to characterize earthquake dynamics and accelerated activity of related faults as far as 100's of kilometers along strike. (2) Integrates the geodetic constraints into consistent kinematic descriptions of the deformation field that can in turn be used to characterize the processes that drive geodynamics, including seismic cycle dynamics. In 1991, we installed and occupied a high precision GPS geodetic network to measure transform-related deformation that is partitioned from the Pacific - North America plate boundary northeastward through the Mojave Desert, via the Eastern California shear zone to the Walker Lane. The onset of the M(sub w) = 7.3 June 28, 1992, Landers, California, earthquake sequence within this network poses unique opportunities for continued monitoring of regional surface deformation related to the culmination of a major seismic cycle, characterization of the dynamic behavior of continental lithosphere during the seismic sequence, and post-seismic transient deformation. During the last year, we have reprocessed all three previous epochs for which JPL fiducial free point positioning products available and are queued for the remaining needed products, completed two field campaigns monitoring approx. 20 sites (October 1995 and September 1996), begun modeling by development of a finite element mesh based on network station locations, and developed manuscripts dealing with both the Landers-related transient deformation at the latitude of Lone Pine and the velocity field of the whole experiment. We are currently deploying a 1997 observation campaign (June 1997). We use GPS geodetic studies to characterize deformation in the Mojave Desert region and related structural domains to the north, and geophysical modeling of lithospheric behavior. The modeling is constrained by our

Tracking Small Satellites using Translated GPS

OpenAIRE

Lefevre, Don; Mulally, Daniel

1991-01-01

This paper discusses using translated GPS for tracking small satellites, the technical trade-offs involved, and the position and timing accuracies which are achievable using translated GPS. The Global Positioning System (GPS) uses the relative times-of-arrival of multiple spread-spectrum signals at an antenna to determine the position of the antenna. The system can also determine the time the antenna was at that position. The direct sequence spread spectrum signals are transmitted from GPS sa...

Evidential recovery from GPS devices

Directory of Open Access Journals (Sweden)

Brian Cusack

Full Text Available Global Positioning Systems (GPS have become more affordable, are now widely used in motor vehicles and in other frequently used applications. As a consequence GPS are increasingly becoming an important source of evidential data for digital forensic investigations. This paper acknowledges there are only disparate documents for the guidance of an investigator when extracting evidence form such systems. The focus of this paper is to provide the technical details of recovering artifacts from four GPS currently available to the New Zealand market. Navman brand GPS are used, following a forensically robust process. The steps of the process are described, results analysed and the associated risks are discussed. In addition, the paper discusses techniques related to the visual presentation of evidence suitable for Google Maps. Automation attempts to speed up the analysis to visualization steps are also included. The outcome is a road map that may assist digital forensic investigators develop GPS examination strategies for implementation in their own organizations.

Novel Hybrid of LS-SVM and Kalman Filter for GPS/INS Integration

Science.gov (United States)

Xu, Zhenkai; Li, Yong; Rizos, Chris; Xu, Xiaosu

Integration of Global Positioning System (GPS) and Inertial Navigation System (INS) technologies can overcome the drawbacks of the individual systems. One of the advantages is that the integrated solution can provide continuous navigation capability even during GPS outages. However, bridging the GPS outages is still a challenge when Micro-Electro-Mechanical System (MEMS) inertial sensors are used. Methods being currently explored by the research community include applying vehicle motion constraints, optimal smoother, and artificial intelligence (AI) techniques. In the research area of AI, the neural network (NN) approach has been extensively utilised up to the present. In an NN-based integrated system, a Kalman filter (KF) estimates position, velocity and attitude errors, as well as the inertial sensor errors, to output navigation solutions while GPS signals are available. At the same time, an NN is trained to map the vehicle dynamics with corresponding KF states, and to correct INS measurements when GPS measurements are unavailable. To achieve good performance it is critical to select suitable quality and an optimal number of samples for the NN. This is sometimes too rigorous a requirement which limits real world application of NN-based methods.The support vector machine (SVM) approach is based on the structural risk minimisation principle, instead of the minimised empirical error principle that is commonly implemented in an NN. The SVM can avoid local minimisation and over-fitting problems in an NN, and therefore potentially can achieve a higher level of global performance. This paper focuses on the least squares support vector machine (LS-SVM), which can solve highly nonlinear and noisy black-box modelling problems. This paper explores the application of the LS-SVM to aid the GPS/INS integrated system, especially during GPS outages. The paper describes the principles of the LS-SVM and of the KF hybrid method, and introduces the LS-SVM regression algorithm. Field

Applications of GPS technologies to field sports.

Science.gov (United States)

Aughey, Robert J

2011-09-01

Global positioning system (GPS) technology was made possible after the invention of the atomic clock. The first suggestion that GPS could be used to assess the physical activity of humans followed some 40 y later. There was a rapid uptake of GPS technology, with the literature concentrating on validation studies and the measurement of steady-state movement. The first attempts were made to validate GPS for field sport applications in 2006. While GPS has been validated for applications for team sports, some doubts continue to exist on the appropriateness of GPS for measuring short high-velocity movements. Thus, GPS has been applied extensively in Australian football, cricket, hockey, rugby union and league, and soccer. There is extensive information on the activity profile of athletes from field sports in the literature stemming from GPS, and this includes total distance covered by players and distance in velocity bands. Global positioning systems have also been applied to detect fatigue in matches, identify periods of most intense play, different activity profiles by position, competition level, and sport. More recent research has integrated GPS data with the physical capacity or fitness test score of athletes, game-specific tasks, or tactical or strategic information. The future of GPS analysis will involve further miniaturization of devices, longer battery life, and integration of other inertial sensor data to more effectively quantify the effort of athletes.

Political Campaigns

OpenAIRE

Lilleker, Darren

2017-01-01

Political campaigns are orchestrated attempts by political organizations to garner public support through persuasive communication in order to influence public policy in their favor. This broad definition encapsulates all forms of campaigns from those of neighborhood organizations seeking to influence local politicians to the campaigns of political parties and candidates who seek election to office in order to shape policy themselves. In pluralist democracies, campaigns are crucial for repres...

Mesure GPS sur le circuit du LIER à Lyon

OpenAIRE

GIRARD, PL; MARAIS, J

2006-01-01

Depuis quelques années le guidage immatériel pour les autobus est à l'ordre du jour et la localisation est une des contraintes à son développement. Pour subvenir à ces besoins la solution GPS est envisagée. Cette technologie en devenir comporte énormément d'avantage notamment en terme coût et de maintenance. L'expérimentation faite à Lyon met en évidence les performances maximales pouvant être obtenu en utilisant le GPS. RAPPORT DE CONTRAT

Determining slack tide with a GPS receiver on an anchored buoy

Science.gov (United States)

Valk, M.; Savenije, H. H. G.; Tiberius, C. C. J. M.; Luxemburg, W. M. J.

2014-07-01

In this paper we present a novel method to determine the time of occurrence of tidal slack with a GPS receiver mounted on an anchored buoy commonly used to delineate shipping lanes in estuaries and tidal channels. Slack tide occurs when the tide changes direction from ebb to flood flow or from flood to ebb. The determination of this point in time is not only useful for shipping and salvaging, it is also important information for calibrating tidal models, for determining the maximum salt intrusion and for the further refinement of the theory on tidal propagation. The accuracy of the timing is well within 10 min and the method - able to operate in real time - is relatively cheap and easy to implement on a permanent basis or in short field campaigns.

Performance enhancement for a GPS vector-tracking loop utilizing an adaptive iterated extended Kalman filter.

Science.gov (United States)

Chen, Xiyuan; Wang, Xiying; Xu, Yuan

2014-12-09

This paper deals with the problem of state estimation for the vector-tracking loop of a software-defined Global Positioning System (GPS) receiver. For a nonlinear system that has the model error and white Gaussian noise, a noise statistics estimator is used to estimate the model error, and based on this, a modified iterated extended Kalman filter (IEKF) named adaptive iterated Kalman filter (AIEKF) is proposed. A vector-tracking GPS receiver utilizing AIEKF is implemented to evaluate the performance of the proposed method. Through road tests, it is shown that the proposed method has an obvious accuracy advantage over the IEKF and Adaptive Extended Kalman filter (AEKF) in position determination. The results show that the proposed method is effective to reduce the root-mean-square error (RMSE) of position (including longitude, latitude and altitude). Comparing with EKF, the position RMSE values of AIEKF are reduced by about 45.1%, 40.9% and 54.6% in the east, north and up directions, respectively. Comparing with IEKF, the position RMSE values of AIEKF are reduced by about 25.7%, 19.3% and 35.7% in the east, north and up directions, respectively. Compared with AEKF, the position RMSE values of AIEKF are reduced by about 21.6%, 15.5% and 30.7% in the east, north and up directions, respectively.

Integrated Campaign Probabilistic Cost, Schedule, Performance, and Value for Program Office Support

Science.gov (United States)

Cornelius, David; Sasamoto, Washito; Daugherty, Kevin; Deacon, Shaun

2012-01-01

This paper describes an integrated assessment tool developed at NASA Langley Research Center that incorporates probabilistic analysis of life cycle cost, schedule, launch performance, on-orbit performance, and value across a series of planned space-based missions, or campaign. Originally designed as an aid in planning the execution of missions to accomplish the National Research Council 2007 Earth Science Decadal Survey, it utilizes Monte Carlo simulation of a series of space missions for assessment of resource requirements and expected return on investment. Interactions between simulated missions are incorporated, such as competition for launch site manifest, to capture unexpected and non-linear system behaviors. A novel value model is utilized to provide an assessment of the probabilistic return on investment. A demonstration case is discussed to illustrate the tool utility.

GPS: Shaping Student Success One Conversation at a Time

Science.gov (United States)

Star, Mikhael; Collette, Lanita

2010-01-01

Increasing instructor-student interactions and improving support personnel interventions with students positively affects their academic performance, retention, and graduation rates. This article discusses the Grade Performance Status (GPS) which is Northern Arizona University's new online, academic early alert tool for increasing instructor…

GPS synchronized power system phase angle measurements

Science.gov (United States)

Wilson, Robert E.; Sterlina, Patrick S.

1994-09-01

This paper discusses the use of Global Positioning System (GPS) synchronized equipment for the measurement and analysis of key power system quantities. Two GPS synchronized phasor measurement units (PMU) were installed before testing. It was indicated that PMUs recorded the dynamic response of the power system phase angles when the northern California power grid was excited by the artificial short circuits. Power system planning engineers perform detailed computer generated simulations of the dynamic response of the power system to naturally occurring short circuits. The computer simulations use models of transmission lines, transformers, circuit breakers, and other high voltage components. This work will compare computer simulations of the same event with field measurement.

GPS Interference Mitigation Using Derivative-free Kalman Filter-based RNN

Directory of Open Access Journals (Sweden)

W. L. Mao

2016-09-01

Full Text Available The global positioning system (GPS with accurate positioning and timing properties has become integral part of all applications around the world. Radio frequency interference can significantly decrease the performance of GPS receivers or even completely prohibit the acquisition or tracking of satellites. The approaches of system performances that can be further enhanced by preprocessing to reject the jamming signal will be investigated. A recurrent neural network (RNN predictor for the GPS anti-jamming applications will be proposed. The adaptive RNN predictor is utilized to accurately predict the narrowband waveform based on an unscented Kalman filter (UKF-based algorithm. The UKF algorithm as a derivative-free alternative to the extended Kalman filter (EKF in the framework of state-estimation is adopted to achieve better performance in terms of convergence rate and quality of solution. The adaptive RNN filter can be successfully applied for the suppression of interference with a number of different narrowband formats, i.e. continuous wave interference (CWI, multi-tone CWI, swept CWI and pulsed CWI, to emulate realistic circumstances. Simulation results show that the proposed UKF-based scheme can offer the superior performances to suppress the interference over the conventional methods by computing mean squared prediction error (MSPE and signal-to-noise ratio (SNR improvements.

GPS Ephemeris Message Broadcast Simulation

National Research Council Canada - National Science Library

Browne, Nathan J; Light, James J

2005-01-01

The warfighter constantly needs increased accuracy from GPS and a means to increasing this accuracy to the decimeter level is a broadcast ephemeris message containing GPS satellite orbit and clock corrections...

Autonomous GPS/INS navigation experiment for Space Transfer Vehicle

Science.gov (United States)

Upadhyay, Triveni N.; Cotterill, Stephen; Deaton, A. W.

1993-01-01

An experiment to validate the concept of developing an autonomous integrated spacecraft navigation system using on board Global Positioning System (GPS) and Inertial Navigation System (INS) measurements is described. The feasibility of integrating GPS measurements with INS measurements to provide a total improvement in spacecraft navigation performance, i.e. improvement in position, velocity and attitude information, was previously demonstrated. An important aspect of this research is the automatic real time reconfiguration capability of the system designed to respond to changes in a spacecraft mission under the control of an expert system.

Design and implementation of the GPS subsystem for the Radio Aurora eXplorer

Science.gov (United States)

Spangelo, Sara C.; Bennett, Matthew W.; Meinzer, Daniel C.; Klesh, Andrew T.; Arlas, Jessica A.; Cutler, James W.

2013-06-01

This paper presents the design and implementation of the Global Positioning System (GPS) subsystem for the Radio Aurora eXplorer (RAX) CubeSat. The GPS subsystem provides accurate temporal and spatial information necessary to satisfy the science objectives of the RAX mission. There are many challenges in the successful design and implementation of a GPS subsystem for a CubeSat-based mission, including power, size, mass, and financial constraints. This paper presents an approach for selecting and testing the individual and integrated GPS subsystem components, including the receiver, antenna, low noise amplifier, and supporting circuitry. The procedures to numerically evaluate the GPS link budget and test the subsystem components at various stages of system integration are described. Performance results for simulated tests in the terrestrial and orbital environments are provided, including start-up times, carrier-to-noise ratios, and orbital position accuracy. Preliminary on-orbit GPS results from the RAX-1 and RAX-2 spacecraft are presented to validate the design process and pre-flight simulations. Overall, this paper provides a systematic approach to aid future satellite designers in implementing and verifying GPS subsystems for resource-constrained small satellites.

How GPs value guidelines applied to patients with multimorbidity: a qualitative study.

Science.gov (United States)

Luijks, Hilde; Lucassen, Peter; van Weel, Chris; Loeffen, Maartje; Lagro-Janssen, Antoine; Schermer, Tjard

2015-10-26

To explore and describe the value general practitioner (GPs) attribute to medical guidelines when they are applied to patients with multimorbidity, and to describe which benefits GPs experience from guideline adherence in these patients. Also, we aimed to identify limitations from guideline adherence in patients with multimorbidity, as perceived by GPs, and to describe their empirical solutions to manage these obstacles. Focus group study with purposive sampling of participants. Focus groups were guided by an experienced moderator who used an interview guide. Interviews were transcribed verbatim. Data analysis was performed by two researchers using the constant comparison analysis technique and field notes were used in the analysis. Data collection proceeded until saturation was reached. Primary care, eastern part of The Netherlands. Dutch GPs, heterogeneous in age, sex and academic involvement. 25 GPs participated in five focus groups. GPs valued the guidance that guidelines provide, but experienced shortcomings when they were applied to patients with multimorbidity. Taking these patients' personal circumstances into account was regarded as important, but it was impeded by a consistent focus on guideline adherence. Preventative measures were considered less appropriate in (elderly) patients with multimorbidity. Moreover, the applicability of guidelines in patients with multimorbidity was questioned. GPs' extensive practical experience with managing multimorbidity resulted in several empirical solutions, for example, using their 'common sense' to respond to the perceived shortcomings. GPs applying guidelines for patients with multimorbidity integrate patient-specific factors in their medical decisions, aiming for patient-centred solutions. Such integration of clinical experience and best evidence is required to practise evidence-based medicine. More flexibility in pay-for-performance systems is needed to facilitate this integration. Several improvements in

Indoor/Outdoor Seamless Positioning Using Lighting Tags and GPS Cellular Phones for Personal Navigation

Science.gov (United States)

Namie, Hiromune; Morishita, Hisashi

The authors focused on the development of an indoor positioning system which is easy to use, portable and available for everyone. This system is capable of providing the correct position anywhere indoors, including onboard ships, and was invented in order to evaluate the availability of GPS indoors. Although the performance of GPS is superior outdoors, there has been considerable research regarding indoor GPS involving sensitive GPS, pseudolites (GPS pseudo satellite), RFID (Radio Frequency IDentification) tags, and wireless LAN .However, the positioning rate and the precision are not high enough for general use, which is the reason why these technologies have not yet spread to personal navigation systems. In this regard, the authors attempted to implement an indoor positioning system using cellular phones with built-in GPS and infrared light data communication functionality, which are widely used in Japan. GPS is becoming increasingly popular, where GPGGS sentences of the NMEA outputted from the GPS receiver provide spatiotemporal information including latitude, longitude, altitude, and time or ECEF xyz coordinates. As GPS applications grow rapidly, spatiotemporal data becomes key to the ubiquitous outdoor and indoor seamless positioning services at least for the entire area of Japan, as well as to becoming familiar with satellite positioning systems (e.g. GPS). Furthermore, the authors are also working on the idea of using PDAs (Personal Digital Assistants), as cellular phones with built-in GPS and PDA functionality are also becoming increasingly popular.

Evaluation of operating experience: The precursor study (GPS) performed in the Federal Republic of Germany. Working material

International Nuclear Information System (INIS)

1991-01-01

Probabilistic Safety Assessments (PSAs) are systematic and quantitative predictions of possible accident scenarios at technical installations on the basis of data gained from the past experience on similar technical installations. For supporting PSAs by operational experience as far as possible Precursor studies are performed. An Accident Sequence Precursor is defined as an observed event which could results, in coincidence with additional postulated events, in a potential severe core damage accident. In the presented case study the procedure of such Precursor studies is explained. Particularly, the methodology and the results of the plant-specific Precursor (GPS) performed in the Federal Republic of Germany are shown in detail. 26 refs, 13 figs, 8 tabs

Evaluation of operating experience: The precursor study (GPS) performed in the Federal Republic of Germany. Working material

Energy Technology Data Exchange (ETDEWEB)

NONE

1992-12-31

Probabilistic Safety Assessments (PSAs) are systematic and quantitative predictions of possible accident scenarios at technical installations on the basis of data gained from the past experience on similar technical installations. For supporting PSAs by operational experience as far as possible Precursor studies are performed. An Accident Sequence Precursor is defined as an observed event which could results, in coincidence with additional postulated events, in a potential severe core damage accident. In the presented case study the procedure of such Precursor studies is explained. Particularly, the methodology and the results of the plant-specific Precursor (GPS) performed in the Federal Republic of Germany are shown in detail. 26 refs, 13 figs, 8 tabs.

Radon campaigns. Status report 2008

International Nuclear Information System (INIS)

Arvela, H.; Valmari, T.; Reisbacka, H.; Niemelae, H.; Oinas, T.; Maekelaeinen, I.; Laitinen-Sorvari, R.

2008-12-01

Radon campaigns aim at activating citizens to make indoor radon measurements and remediation as well as increasing the common awareness of indoor radon questions. Indoor radon increases the risk of lung cancer. Through radon campaigns Radiation and Nuclear Safety Authority (STUK) also promotes the attainment of those goals that the Ministry of Social Affairs and Health has set for municipal authorities in Finland for prevention of the harmful effects of radon. The Ministry of Social Affairs and Health supports this campaign. Radon campaigns were started in autumn 2003. By autumn 2008 the campaigns have been organised already in 64 regions altogether in 160 municipalities. In some municipalities they have already arranged two campaigns. Altogether 14 100 houses have been measured and in 2 100 of these the action limit of radon remediation 400 Bq / m 3 has been exceeded. When participating in radon campaigns the house owners receive a special offer on radon detectors with a reduced price. In 2008 a new practice was introduced where the campaign advertisements were distributed by mail to low-rise residential houses in a certain region. The advertisement includes an order / deposit slip with postage paid that the house owner can send directly to STUK to easily make an order for radon measurement. In the previous radon campaigns in 2003 - 2007 the municipal authorities collected the orders from house owners and distributed later the radon detectors. The radon concentrations measured in the campaign regions have exceeded the action limit of 400 Bq / m 3 in 0 - 39% of houses, depending on the region. The total of 15% of all measurements made exceeded this limit. The remediation activities have been followed by sending a special questionnaire on remedies performed to the house owners. In 2006 - 2007 a questionnaire was sent to those households where the radon concentration of 400 Bq / m 3 was exceeded during the two first campaign seasons. Among the households that replied

Implementing GPS into Pave-IR.

Science.gov (United States)

2009-03-01

To further enhance the capabilities of the Pave-IR thermal segregation detection system developed at the Texas Transportation Institute, researchers incorporated global positioning system (GPS) data collection into the thermal profiles. This GPS capa...

GPS Navigation and Tracking Device

Directory of Open Access Journals (Sweden)

Yahya Salameh Khraisat

2011-10-01

Full Text Available Since the introduction of GPS Navigation systems in the marketplace, consumers and businesses have been coming up with innovative ways to use the technology in their everyday life. GPS Navigation and Tracking systems keep us from getting lost when we are in strange locations, they monitor children when they are away from home, keep track of business vehicles and can even let us know where a philandering partner is at all times. Because of this we attend to build a GPS tracking device to solve the mentioned problems. Our work consists of the GPS module that collects data from satellites and calculates the position information before transmitting them to the user’s PC (of Navigation system or observers (of Tracking System using wireless technology (GSM.

The GPS Laser Retroreflector Array Project

Science.gov (United States)

Merkowitz, Stephen M.

2012-01-01

Systematic co-location in space through the precision orbit determination of GPS satellites via satellite laser ranging will contribute significantly towards improving the accuracy and stability of the international terrestrial reference frame. NASA recently formed the GPS Laser Retroreflector Array Project to develop and deliver retroreflectors for integration on the next generation of GPS satellites. These retroreflectors will be an important contributor to achieving a global accuracy of 1.0 mm and 0.1 mm/year stability in the international terrestrial reference frame. We report here the current status of the GPS Laser Retroreflector Array Project.

GPS Water Vapor Tomography Based on Accurate Estimations of the GPS Tropospheric Parameters

Science.gov (United States)

Champollion, C.; Masson, F.; Bock, O.; Bouin, M.; Walpersdorf, A.; Doerflinger, E.; van Baelen, J.; Brenot, H.

2003-12-01

The Global Positioning System (GPS) is now a common technique for the retrieval of zenithal integrated water vapor (IWV). Further applications in meteorology need also slant integrated water vapor (SIWV) which allow to precisely define the high variability of tropospheric water vapor at different temporal and spatial scales. Only precise estimations of IWV and horizontal gradients allow the estimation of accurate SIWV. We present studies developed to improve the estimation of tropospheric water vapor from GPS data. Results are obtained from several field experiments (MAP, ESCOMPTE, OHM-CV, IHOP, .). First IWV are estimated using different GPS processing strategies and results are compared to radiosondes. The role of the reference frame and the a priori constraints on the coordinates of the fiducial and local stations is generally underestimated. It seems to be of first order in the estimation of the IWV. Second we validate the estimated horizontal gradients comparing zenith delay gradients and single site gradients. IWV, gradients and post-fit residuals are used to construct slant integrated water delays. Validation of the SIWV is under progress comparing GPS SIWV, Lidar measurements and high resolution meteorological models (Meso-NH). A careful analysis of the post-fit residuals is needed to separate tropospheric signal from multipaths. The slant tropospheric delays are used to study the 3D heterogeneity of the troposphere. We develop a tomographic software to model the three-dimensional distribution of the tropospheric water vapor from GPS data. The software is applied to the ESCOMPTE field experiment, a dense network of 17 dual frequency GPS receivers operated in southern France. Three inversions have been successfully compared to three successive radiosonde launches. Good resolution is obtained up to heights of 3000 m.

Towards Sustainability in Viral Marketing with User Engaging Supporting Campaigns

Directory of Open Access Journals (Sweden)

Jarosław Jankowski

2017-12-01

Full Text Available While viral marketing has captured substantial academic and professional interest, the processes that underpin successful viral marketing campaigns remain poorly understood. High competition and pressure for successful campaigns lead to strategies based on persuasion, unsolicited messages, and other techniques that negatively affect brand perception. The need for more sustainable strategies with a limited negative impact on web users is observed. Therefore, the current study examines the effectiveness of viral marketing and a supporting campaign, where the main goal was to increase user engagement and overall campaign performance. Supporting campaigns were evaluated, to determine whether they enhanced viral activity, but without the need for high persuasion or intrusive techniques. Results showed that supporting actions could be integrated with lower performing campaigns to increase their effectiveness. Apart from the main scientific goal that is presented, the study demonstrates how virtual worlds can provide a laboratory-like environment for identifying the processes that underpin viral marketing.

Ninth Processing Campaign in the Waste Calcining Facility

International Nuclear Information System (INIS)

Childs, K.F.; Donovan, R.I.; Swenson, M.C.

1982-04-01

This report discusses the Ninth (and final) Processing Campaign at the Waste Calcining Facility. Several processing interruptions were experienced during this campaign and the emphasis of this report is on process and equipment performance with operating problems and corrective actions discussed in detail

Geomagnetic storms, super-storms, and their impacts on GPS-based navigation systems

Science.gov (United States)

Astafyeva, E.; Yasyukevich, Yu.; Maksikov, A.; Zhivetiev, I.

2014-07-01

Using data of GPS receivers located worldwide, we analyze the quality of GPS performance during four geomagnetic storms of different intensity: two super-storms and two intense storms. We show that during super-storms the density of GPS Losses-of-Lock (LoL) increases up to 0.25% at L1 frequency and up to 3% at L2 frequency, and up to 0.15% (at L1) and 1% (at L2) during less intense storms. Also, depending on the intensity of the storm time ionospheric disturbances, the total number of total electron content (TEC) slips can exceed from 4 to 40 times the quiet time level. Both GPS LoL and TEC slips occur during abrupt changes of SYM-H index of geomagnetic activity, i.e., during the main phase of geomagnetic storms and during development of ionospheric storms. The main contribution in the total number of GPS LoL was found to be done by GPS sites located at low and high latitudes, whereas the area of numerous TEC slips seemed to mostly correspond to the boundary of the auroral oval, i.e., region with intensive ionospheric irregularities. Our global maps of TEC slips show where the regions with intense irregularities of electron density occur during geomagnetic storms and will let us in future predict appearance of GPS errors for geomagnetically disturbed conditions.

A Simultaneously Calibration Approach for Installation and Attitude Errors of an INS/GPS/LDS Target Tracker

Directory of Open Access Journals (Sweden)

Jianhua Cheng

2015-02-01

Full Text Available To obtain the absolute position of a target is one of the basic topics for non-cooperated target tracking problems. In this paper, we present a simultaneously calibration method for an Inertial navigation system (INS/Global position system (GPS/Laser distance scanner (LDS integrated system based target positioning approach. The INS/GPS integrated system provides the attitude and position of observer, and LDS offers the distance between the observer and the target. The two most significant errors are taken into jointly consideration and analyzed: (1 the attitude measure error of INS/GPS; (2 the installation error between INS/GPS and LDS subsystems. Consequently, a INS/GPS/LDS based target positioning approach considering these two errors is proposed. In order to improve the performance of this approach, a novel calibration method is designed to simultaneously estimate and compensate these two main errors. Finally, simulations are conducted to access the performance of the proposed target positioning approach and the designed simultaneously calibration method.

A simultaneously calibration approach for installation and attitude errors of an INS/GPS/LDS target tracker.

Science.gov (United States)

Cheng, Jianhua; Chen, Daidai; Sun, Xiangyu; Wang, Tongda

2015-02-04

To obtain the absolute position of a target is one of the basic topics for non-cooperated target tracking problems. In this paper, we present a simultaneously calibration method for an Inertial navigation system (INS)/Global position system (GPS)/Laser distance scanner (LDS) integrated system based target positioning approach. The INS/GPS integrated system provides the attitude and position of observer, and LDS offers the distance between the observer and the target. The two most significant errors are taken into jointly consideration and analyzed: (1) the attitude measure error of INS/GPS; (2) the installation error between INS/GPS and LDS subsystems. Consequently, a INS/GPS/LDS based target positioning approach considering these two errors is proposed. In order to improve the performance of this approach, a novel calibration method is designed to simultaneously estimate and compensate these two main errors. Finally, simulations are conducted to access the performance of the proposed target positioning approach and the designed simultaneously calibration method.

A GPS measurement system for precise satellite tracking and geodesy

Science.gov (United States)

Yunck, T. P.; Wu, S.-C.; Lichten, S. M.

1985-01-01

NASA is pursuing two key applications of differential positioning with the Global Positioning System (GPS): sub-decimeter tracking of earth satellites and few-centimeter determination of ground-fixed baselines. Key requirements of the two applications include the use of dual-frequency carrier phase data, multiple ground receivers to serve as reference points, simultaneous solution for use position and GPS orbits, and calibration of atmospheric delays using water vapor radiometers. Sub-decimeter tracking will be first demonstrated on the TOPEX oceanographic satellite to be launched in 1991. A GPS flight receiver together with at least six ground receivers will acquire delta range data from the GPS carriers for non-real-time analysis. Altitude accuracies of 5 to 10 cm are expected. For baseline measurements, efforts will be made to obtain precise differential pseudorange by resolving the cycle ambiguity in differential carrier phase. This could lead to accuracies of 2 or 3 cm over a few thousand kilometers. To achieve this, a high-performance receiver is being developed, along with improved calibration and data processing techniques. Demonstrations may begin in 1986.

The Campaign: a case study in identity construction through performance

Directory of Open Access Journals (Sweden)

Matthew D. Riddle

2009-12-01

Full Text Available This article undertakes a detailed case study of The Campaign, a teaching and learning innovation in media and communications that uses an online educational role-play. The case study draws on the qualitative analysis of classroom observations, online communications and semi-structured interviews, employing an interpretive approach informed by models drawn from social theory and sociotechnical theory. Educational authors argue that online educational role-plays engage students in authentic learning, and represent an improvement over didactic teaching strategies. According to this literature, online role-play systems afford students the opportunity of acting and doing instead of only reading and listening. Literature in social theory and social studies of technology takes a different view of certain concepts such as performance, identity and reality. Models such as performative self constitution and actor network theory ask us to consider the constructed nature of identity and the roles of all of the actors, including the system itself. This article examines these concepts by addressing a series of research questions relating to identity formation and mediation, and suggests certain limitations of the situationist perspective in explaining the educational value of role-play systems.

Precise GPS orbits for geodesy

Science.gov (United States)

Colombo, Oscar L.

1994-01-01

The Global Positioning System (GPS) has become, in recent years, the main space-based system for surveying and navigation in many military, commercial, cadastral, mapping, and scientific applications. Better receivers, interferometric techniques (DGPS), and advances in post-processing methods have made possible to position fixed or moving receivers with sub-decimeter accuracies in a global reference frame. Improved methods for obtaining the orbits of the GPS satellites have played a major role in these achievements; this paper gives a personal view of the main developments in GPS orbit determination.

GPS on Every Roof, GPS Sensor Network for Post-Seismic Building-Wise Damage Identification

Directory of Open Access Journals (Sweden)

Kenji Oguni

2013-12-01

Full Text Available Development of wireless sensor network equipped with GPS for post-seismic building-wise damage identification is presented in this paper. This system is called GPS on Every Roof. Sensor node equipped with GPS antenna and receiver is installed on the top of the roof of each and every building. The position of this sensor node is measured before and after earthquake. The final goal of this system is to i identify the displacement of the roof of each house and ii collect the information of displacement of the roof of the houses through wireless communication. Superposing this information on GIS, building-wise damage distribution due to earthquake can be obtained. The system overview, hardware and some of the key components of the system such as on-board GPS relative positioning algorithm to achieve the accuracy in the order of several centimeters are described in detail. Also, the results from a field experiment using a wireless sensor network with 39 sensor nodes are presented.

GPS satellite surveying

CERN Document Server

Leick, Alfred; Tatarnikov, Dmitry

2015-01-01

THE MOST COMPREHENSIVE, UP-TO-DATE GUIDE ON GPS TECHNOLOGY FOR SURVEYING Three previous editions have established GPS Satellite Surveying as the definitive industry reference. Now fully updated and expanded to reflect the newest developments in the field, this Fourth Edition features cutting-edge information on GNSS antennas, precise point positioning, real-time relative positioning, lattice reduction, and much more. Expert authors examine additional tools and applications, offering complete coverage of geodetic surveying using satellite technologies. The past decade has seen a major evolut

The GPS odograph user's guide

Science.gov (United States)

The GPS-based Odograph Prototype (GOP or GPS Odograph) was developed in an effort sponsored by The Federal Highway Administration (FHWA). The purpose of this effort was to develop a means of using inexpensive commercial off-the-self laptop (or notebo...

High Gain Advanced GPS Receiver

National Research Council Canada - National Science Library

Brown, Alison; Zhang, Gengsheng

2006-01-01

NAVSYS High Gain Advanced GPS Receiver (HAGR) uses a digital beam-steering antenna array to enable up to eight GPS satellites to be tracked, each with up to 10 dBi of additional antenna gain over a conventional receiver solution...

Signal existence verification (SEV) for GPS low received power signal detection using the time-frequency approach.

Science.gov (United States)

Jan, Shau-Shiun; Sun, Chih-Cheng

2010-01-01

The detection of low received power of global positioning system (GPS) signals in the signal acquisition process is an important issue for GPS applications. Improving the miss-detection problem of low received power signal is crucial, especially for urban or indoor environments. This paper proposes a signal existence verification (SEV) process to detect and subsequently verify low received power GPS signals. The SEV process is based on the time-frequency representation of GPS signal, and it can capture the characteristic of GPS signal in the time-frequency plane to enhance the GPS signal acquisition performance. Several simulations and experiments are conducted to show the effectiveness of the proposed method for low received power signal detection. The contribution of this work is that the SEV process is an additional scheme to assist the GPS signal acquisition process in low received power signal detection, without changing the original signal acquisition or tracking algorithms.

Feasibility study and technical proposal for long-term observations of bedrock stability with gps

International Nuclear Information System (INIS)

Ruizhi Chen; Kakkuri, J.

1994-01-01

In order to study the regional crustal deformation pattern in the territory of Finland, the Finnish Geodetic Institute is establishing the Finnish Permanent GPS Network, which is part of the Fennoscandian Permanent GPS Network. The Finnish GPS Network consists of a 12 stations located in different geological structures. The operation procedure of the network is described in the report. Feasibility study for monitoring the bedrock stability at local scale was performed. The study was carried out on the basis of an experiment on a baseline of 1041 metres. Twelve artificial movements ranging from 1 mm to 22 mm were generated with a precision-manufactured screw drive (with an accuracy of better than +-0.05 mm). The artificial movements were then detected with the GPS measurements. A preliminary analysis of the GPS data shows that the maximum difference between the GPS detected movements and the artificial movements is 0.9 mm with a standard deviation of +-0.46 mm. The observation time for reaching such accuracy is about 55 minutes. Three GPS networks were preliminarily designed for the radioactive waste disposal investigation sites of Olkiluoto, Kivetty and Romuvaara. Detailed research plan for achieving the best possible result from GPS measurements was proposed. (58 refs., 25 figs., 1 tab.)

Field Campaign Guidelines

Energy Technology Data Exchange (ETDEWEB)

Voyles, J. W. [DOE ARM Climate Research Facility, Washington, DC (United States); Chapman, L. A. [DOE ARM Climate Research Facility, Washington, DC (United States)

2015-12-01

This document establishes a common set of guidelines for the Atmospheric Radiation Measurement (ARM) Climate Research Facility for planning, executing, and closing out field campaigns. The steps that guide individual field campaigns are described in the Field Campaign Tracking System and are specifically tailored to meet the scope of each field campaign.

Comparison of attitude determination approaches using multiple Global Positioning System (GPS antennas

Directory of Open Access Journals (Sweden)

Wang Bing

2013-02-01

Full Text Available GPS-based attitude system is an important research field, since it is a valuable technique for the attitude determination of platforms. There exist two classes approaches for attitude determination using the GPS. The one determines attitude via baseline estimates in two frames, the other one solves for attitude by incorporating the attitude parameters directly into the GPS measurements. However, comparisons between these two classes approaches have been unexplored. First of all, two algorithms are introduced in detail which on behalf of these two kinds of approaches. Then we present numerical simulations demonstrating the performance of our algorithms and provide a comparison evaluating.

Studying Landslide Displacements in Megamendung (Indonesia Using GPS Survey Method

Directory of Open Access Journals (Sweden)

Hasanuddin Z. Abidin

2004-11-01

Full Text Available Landslide is one of prominent geohazards that frequently affects Indonesia, especially in the rainy season. It destroys not only environment and property, but usually also causes deaths. Landslide monitoring is therefore very crucial and should be continuously done. One of the methods that can have a contribution in studying landslide phenomena is repeated GPS survey method. This paper presents and discusses the operational performances, constraints and results of GPS surveys conducted in a well known landslide prone area in West Java (Indonesia, namely Megamendung, the hilly region close to Bogor. Three GPS surveys involving 8 GPS points have been conducted, namely on April 2002, May 2003 and May 2004, respectively. The estimated landslide displacements in the area are relatively quite large in the level of a few dm to a few m. Displacements up to about 2-3 m were detected in the April 2002 to May 2003 period, and up to about 3-4 dm in the May 2003 to May 2004 period. In both periods, landslides in general show the northwest direction of displacements. Displacements vary both spatially and temporally. This study also suggested that in order to conclude the existence of real and significant displacements of GPS points, the GPS estimated displacements should be subjected to three types of testing namely: the congruency test on spatial displacements, testing on the agreement between the horizontal distance changes with the predicted direction of landslide displacement, and testing on the consistency of displacement directions on two consecutive periods.

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.

Miniaturized GPS/MEMS IMU integrated board

Science.gov (United States)

Lin, Ching-Fang (Inventor)

2012-01-01

This invention documents the efforts on the research and development of a miniaturized GPS/MEMS IMU integrated navigation system. A miniaturized GPS/MEMS IMU integrated navigation system is presented; Laser Dynamic Range Imager (LDRI) based alignment algorithm for space applications is discussed. Two navigation cameras are also included to measure the range and range rate which can be integrated into the GPS/MEMS IMU system to enhance the navigation solution.

Mobility assessment of a rural population in the Netherlands using GPS measurements.

Science.gov (United States)

Klous, Gijs; Smit, Lidwien A M; Borlée, Floor; Coutinho, Roel A; Kretzschmar, Mirjam E E; Heederik, Dick J J; Huss, Anke

2017-08-09

The home address is a common spatial proxy for exposure assessment in epidemiological studies but mobility may introduce exposure misclassification. Mobility can be assessed using self-reports or objectively measured using GPS logging but self-reports may not assess the same information as measured mobility. We aimed to assess mobility patterns of a rural population in the Netherlands using GPS measurements and self-reports and to compare GPS measured to self-reported data, and to evaluate correlates of differences in mobility patterns. In total 870 participants filled in a questionnaire regarding their transport modes and carried a GPS-logger for 7 consecutive days. Transport modes were assigned to GPS-tracks based on speed patterns. Correlates of measured mobility data were evaluated using multiple linear regression. We calculated walking, biking and motorised transport durations based on GPS and self-reported data and compared outcomes. We used Cohen's kappa analyses to compare categorised self-reported and GPS measured data for time spent outdoors. Self-reported time spent walking and biking was strongly overestimated when compared to GPS measurements. Participants estimated their time spent in motorised transport accurately. Several variables were associated with differences in mobility patterns, we found for instance that obese people (BMI > 30 kg/m 2 ) spent less time in non-motorised transport (GMR 0.69-0.74) and people with COPD tended to travel longer distances from home in motorised transport (GMR 1.42-1.51). If time spent walking outdoors and biking is relevant for the exposure to environmental factors, then relying on the home address as a proxy for exposure location may introduce misclassification. In addition, this misclassification is potentially differential, and specific groups of people will show stronger misclassification of exposure than others. Performing GPS measurements and identifying explanatory factors of mobility patterns may assist

New method of GPS orbit determination from GCPS network for the purpose of DOP calculations

Directory of Open Access Journals (Sweden)

Aly M. El-naggar

2012-06-01

Full Text Available The accuracy of GPS measurement satisfies the requirements of some applications, but many applications require an improvement of GPS measurement accuracy. For precise positioning by GPS, it is necessary to perform GPS mission planning. The GPS mission planning is a pre-survey task in which the values of Dilution Of Precision (DOP should be predicted for the observation points, this task should determine the best observation periods which meet the project requirements. The main purpose of this work is to study a rather simple but still fairly accurate algorithm to determine the artificial satellite orbits for the purpose of DOP calculation. The orbit determination algorithm proposed in this paper is implemented by using several reference stations and calculated the orbits by new algorithm; inverse GPS. Inverse GPS means that reference stations are considered as satellites and satellite as receiver. This new algorithm used to calculate the satellite orbit which is mainly used to calculate the DOP. A comparison is done between the estimated PDOP by using satellite coordinates from new method and from the SP3 (Standard Product # 3 file.

Hastighedskort for Danmark vha. GPS

DEFF Research Database (Denmark)

Andersen, Ove; Lahrmann, Harry; Torp, Kristian

2011-01-01

Hastighed på vejnettet er en central metrik indenfor trafikplanlægning og trafikoptimering. I denne artikel beskrives, hvorledes et hastighedskort for hele Danmark er skabt udelukkende vha. GPS data. To tilgangsvinkler til at beregne hastigheder vha. GPS data er præsenteret. Dette er hhv. en....... Opsummeret anses den turbaseret for at beregne det mest akkurate estimat, men metoden er meget datakrævende. Det er derfor nødvendigt at have den punktbaserede at falde tilbage på. Generelt mangler metoder til beregning af hastigheder vha. GPS data at blive valideret. Hvordan en sådan validering kan...

Processing horizontal networks measured by integrated terrestrial and GPS technologies

Directory of Open Access Journals (Sweden)

Vincent Jakub

2003-09-01

Full Text Available Local horizontal networks in which GPS and terrestrial measurements (TER are done are often established at present. Iin other networks, the previous terrestrial measurements can be completed with quantities from contemporary GPS observations (tunnel nets, mining nets with surface and underground parts and other long-shaped nets.The processing of such heterobeneous (GPS, TER networks whose terrestrial measurements are performed as point coordinate measurements (∆X, ∆Y using (geodetic total stationIn is presented in this paper. In such network structures it is then available:- the values ∆X, ∆Y from TER observations which are transformed in the plane of S-JTSK for adjustement,- the values ∆X, ∆Y in the plane S-JTSK that can be obtained by 3D transformation of WGS84 netpoint coordinates from GPS observations to corresponding coordinates S-JTSK.For common adjusting all the ∆X, ∆Y, some elements of the network geometry (e.g. distances should be measured by both methods (GPS, TER. This approach makes possible an effective homogenisation of both network parts what is equivalent to saying that an expressive influence reduction on local frame realizations of S-JTSK in the whole network can be made.Results of network processing obtained in proposed manner are acceptable in general and they are equivalent (accuracy, reliability to results of another processing methods.

A Robust High-Performance GPS L1 Receiver with Single-stage Quadrature Redio-Frequency Circuit

Science.gov (United States)

Liu, Jianghua; Xu, Weilin; Wan, Qinq; Liu, Tianci

2018-03-01

A low power current reuse single-stage quadrature raido-frequency part (SQRF) is proposed for GPS L1 receiver in 180nm CMOS process. The proposed circuit consists of LNA, Mixer, QVCO, is called the QLMV cell. A two blocks stacked topology is adopted in this design. The parallel QVCO and mixer placed on the top forms the upper stacked block, and the LNA placed on the bottom forms the other stacked block. The two blocks share the current and achieve low power performance. To improve the stability, a float current source is proposed. The float current isolated the local oscillation signal and the input RF signal, which bring the whole circuit robust high-performance. The result shows conversion gain is 34 dB, noise figure is three dB, the phase noise is -110 dBc/Hz at 1MHz and IIP3 is -20 dBm. The proposed circuit dissipated 1.7mW with 1 V supply voltage.

Tightly coupled low cost 3D RISS/GPS integration using a mixture particle filter for vehicular navigation.

Science.gov (United States)

Georgy, Jacques; Noureldin, Aboelmagd

2011-01-01

Satellite navigation systems such as the global positioning system (GPS) are currently the most common technique used for land vehicle positioning. However, in GPS-denied environments, there is an interruption in the positioning information. Low-cost micro-electro mechanical system (MEMS)-based inertial sensors can be integrated with GPS and enhance the performance in denied GPS environments. The traditional technique for this integration problem is Kalman filtering (KF). Due to the inherent errors of low-cost MEMS inertial sensors and their large stochastic drifts, KF, with its linearized models, has limited capabilities in providing accurate positioning. Particle filtering (PF) was recently suggested as a nonlinear filtering technique to accommodate for arbitrary inertial sensor characteristics, motion dynamics and noise distributions. An enhanced version of PF called the Mixture PF is utilized in this study to perform tightly coupled integration of a three dimensional (3D) reduced inertial sensors system (RISS) with GPS. In this work, the RISS consists of one single-axis gyroscope and a two-axis accelerometer used together with the vehicle's odometer to obtain 3D navigation states. These sensors are then integrated with GPS in a tightly coupled scheme. In loosely-coupled integration, at least four satellites are needed to provide acceptable GPS position and velocity updates for the integration filter. The advantage of the tightly-coupled integration is that it can provide GPS measurement update(s) even when the number of visible satellites is three or lower, thereby improving the operation of the navigation system in environments with partial blockages by providing continuous aiding to the inertial sensors even during limited GPS satellite availability. To effectively exploit the capabilities of PF, advanced modeling for the stochastic drift of the vertically aligned gyroscope is used. In order to benefit from measurement updates for such drift, which are

Tightly Coupled Low Cost 3D RISS/GPS Integration Using a Mixture Particle Filter for Vehicular Navigation

Directory of Open Access Journals (Sweden)

Jacques Georgy

2011-04-01

Full Text Available Satellite navigation systems such as the global positioning system (GPS are currently the most common technique used for land vehicle positioning. However, in GPS-denied environments, there is an interruption in the positioning information. Low-cost micro-electro mechanical system (MEMS-based inertial sensors can be integrated with GPS and enhance the performance in denied GPS environments. The traditional technique for this integration problem is Kalman filtering (KF. Due to the inherent errors of low-cost MEMS inertial sensors and their large stochastic drifts, KF, with its linearized models, has limited capabilities in providing accurate positioning. Particle filtering (PF was recently suggested as a nonlinear filtering technique to accommodate for arbitrary inertial sensor characteristics, motion dynamics and noise distributions. An enhanced version of PF called the Mixture PF is utilized in this study to perform tightly coupled integration of a three dimensional (3D reduced inertial sensors system (RISS with GPS. In this work, the RISS consists of one single-axis gyroscope and a two-axis accelerometer used together with the vehicle’s odometer to obtain 3D navigation states. These sensors are then integrated with GPS in a tightly coupled scheme. In loosely-coupled integration, at least four satellites are needed to provide acceptable GPS position and velocity updates for the integration filter. The advantage of the tightly-coupled integration is that it can provide GPS measurement update(s even when the number of visible satellites is three or lower, thereby improving the operation of the navigation system in environments with partial blockages by providing continuous aiding to the inertial sensors even during limited GPS satellite availability. To effectively exploit the capabilities of PF, advanced modeling for the stochastic drift of the vertically aligned gyroscope is used. In order to benefit from measurement updates for such drift

Autonomous GPS/INS navigation experiment for Space Transfer Vehicle (STV)

Science.gov (United States)

Upadhyay, Triveni N.; Cotterill, Stephen; Deaton, A. Wayne

1991-01-01

An experiment to validate the concept of developing an autonomous integrated spacecraft navigation system using on board Global Positioning System (GPS) and Inertial Navigation System (INS) measurements is described. The feasibility of integrating GPS measurements with INS measurements to provide a total improvement in spacecraft navigation performance, i.e. improvement in position, velocity and attitude information, was previously demonstrated. An important aspect of this research is the automatic real time reconfiguration capability of the system designed to respond to changes in a spacecraft mission under the control of an expert system.

More counselling for end-of-life decisions by GPs with own advance directives: A postal survey among German general practitioners.

Science.gov (United States)

Schnakenberg, Rieke; Radbruch, Lukas; Kersting, Christine; Frank, Friederike; Wilm, Stefan; Becka, Denise; Weckbecker, Klaus; Bleckwenn, Markus; Just, Johannes M; Pentzek, Michael; Weltermann, Birgitta

2018-12-01

Although general practitioners (GPs) are among the preferred contact persons for discussing end-of-life issues including advance directives (ADs), there is little data on how GPs manage such consultations. This postal survey asked German GPs about their counselling for end-of-life decisions. In 2015, a two-sided questionnaire was mailed to 959 GPs. GPs were asked for details of their consultations on ADs: frequency, duration, template use, and whether they have own ADs. Statistical analysis evaluated physician characteristics associated with an above-average number of consultations on AD. The participation rate was 50.3% (n = 482), 70.5% of the GPs were male; the average age was 54 years. GPs had an average of 18 years of professional experience, and 61.4% serve more than 900 patients per three months. Most (96.9%) GPs perform consultations on living wills (LW) and/or powers of attorney (PA), mainly in selected patients (72.3%). More than 20 consultations each on LWs and PAs are performed by 60% and 50% of GPs, respectively. The estimated mean duration of consultations was 21 min for LWs and 16 min for PAs. Predefined templates were used in 72% of the GPs, 50% of GPs had their ADs. A statistical model showed that GPs with ADs and/or a qualification in palliative medicine were more likely to counsel ≥20 patients per year for each document. The study confirmed that nearly all German GPs surveyed provide counselling on ADs. Physicians with ADs counsel more frequently than those without such documents.

Summary of the Blind Test Campaign to predict the High Reynolds number performance of DU00-W-210 airfoil

DEFF Research Database (Denmark)

Yilmaz, Özlem Ceyhan; Pires, Oscar; Munduate, Xabier

2017-01-01

This paper summarizes the results of a blind test campaign organized in the AVATAR project to predict the high Reynolds number performance of a wind turbine airfoil for wind turbine applications. The DU00-W-210 airfoil was tested in the DNW-HDG pressurized wind tunnel in order to investigate...... the flow at high Reynolds number range from 3 to 15 million which is the operating condition of the future large 10MW+ offshore wind turbine rotors. The results of the experiment was used in a blind test campaign to test the prediction capability of the CFD tools used in the wind turbine rotor simulations....... As a result of the blind test campaign it was found that although the codes are in general capable of predicting increased max lift and decreased minimum drag with Re number, the Re trend predictions in particular the glide ratio (lift over drag) need further improvement. In addition to that, the significant...

Lightweight GPS-tags, one giant leap for wildlife tracking? An assessment approach.

Directory of Open Access Journals (Sweden)

Mariano R Recio

Full Text Available Recent technological improvements have made possible the development of lightweight GPS-tagging devices suitable to track medium-to-small sized animals. However, current inferences concerning GPS performance are based on heavier designs, suitable only for large mammals. Lightweight GPS-units are deployed close to the ground, on species selecting micro-topographical features and with different behavioural patterns in comparison to larger mammal species. We assessed the effects of vegetation, topography, motion, and behaviour on the fix success rate for lightweight GPS-collar across a range of natural environments, and at the scale of perception of feral cats (Felis catus. Units deployed at 20 cm above the ground in sites of varied vegetation and topography showed that trees (native forest and shrub cover had the largest influence on fix success rate (89% on average; whereas tree cover, sky availability, number of satellites and horizontal dilution of position (HDOP were the main variables affecting location error (±39.5 m and ±27.6 m before and after filtering outlier fixes. Tests on HDOP or number of satellites-based screening methods to remove inaccurate locations achieved only a small reduction of error and discarded many accurate locations. Mobility tests were used to simulate cats' motion, revealing a slightly lower performance as compared to the fixed sites. GPS-collars deployed on 43 cats showed no difference in fix success rate by sex or season. Overall, fix success rate and location error values were within the range of previous tests carried out with collars designed for larger species. Lightweight GPS-tags are a suitable method to track medium to small size species, hence increasing the range of opportunities for spatial ecology research. However, the effects of vegetation, topography and behaviour on location error and fix success rate need to be evaluated prior to deployment, for the particular study species and their habitats.

Sensing human activity : GPS tracking

NARCIS (Netherlands)

van der Spek, Stefan; van Schaick, Jeroen; de Bois, P.G.; de Haan, Remco

2009-01-01

The enhancement of GPS technology enables the use of GPS devices not only as navigation and orientation tools, but also as instruments used to capture travelled routes: as sensors that measure activity on a city scale or the regional scale. TU Delft developed a process and database architecture for

Fast-Acquisition/Weak-Signal-Tracking GPS Receiver for HEO

Science.gov (United States)

Wintemitz, Luke; Boegner, Greg; Sirotzky, Steve

2004-01-01

A report discusses the technical background and design of the Navigator Global Positioning System (GPS) receiver -- . a radiation-hardened receiver intended for use aboard spacecraft. Navigator is capable of weak signal acquisition and tracking as well as much faster acquisition of strong or weak signals with no a priori knowledge or external aiding. Weak-signal acquisition and tracking enables GPS use in high Earth orbits (HEO), and fast acquisition allows for the receiver to remain without power until needed in any orbit. Signal acquisition and signal tracking are, respectively, the processes of finding and demodulating a signal. Acquisition is the more computationally difficult process. Previous GPS receivers employ the method of sequentially searching the two-dimensional signal parameter space (code phase and Doppler). Navigator exploits properties of the Fourier transform in a massively parallel search for the GPS signal. This method results in far faster acquisition times [in the lab, 12 GPS satellites have been acquired with no a priori knowledge in a Low-Earth-Orbit (LEO) scenario in less than one second]. Modeling has shown that Navigator will be capable of acquiring signals down to 25 dB-Hz, appropriate for HEO missions. Navigator is built using the radiation-hardened ColdFire microprocessor and housing the most computationally intense functions in dedicated field-programmable gate arrays. The high performance of the algorithm and of the receiver as a whole are made possible by optimizing computational efficiency and carefully weighing tradeoffs among the sampling rate, data format, and data-path bit width.

Design of complete software GPS signal simulator with low complexity and precise multipath channel model

Directory of Open Access Journals (Sweden)

G. Arul Elango

2016-09-01

Full Text Available The need for GPS data simulators have become important due to the tremendous growth in the design of versatile GPS receivers. Commercial hardware and software based GPS simulators are expensive and time consuming. In this work, a low cost simple novel GPS L1 signal simulator is designed for testing and evaluating the performance of software GPS receiver in a laboratory environment. A typical real time paradigm, similar to actual satellite derived GPS signal is created on a computer generated scenario. In this paper, a GPS software simulator is proposed that may offer a lot of analysis and testing flexibility to the researchers and developers as it is totally software based primarily running on a laptop/personal computer without the requirement of any hardware. The proposed GPS simulator allows provision for re-configurability and test repeatability and is developed in VC++ platform to minimize the simulation time. It also incorporates Rayleigh multipath channel fading model under non-line of sight (NLOS conditions. In this work, to efficiently design the simulator, several Rayleigh fading models viz. Inverse Discrete Fourier Transform (IDFT, Filtering White Gaussian Noise (FWFN and modified Sum of Sinusoidal (SOS simulators are tested and compared in terms of accuracy of its first and second order statistical metrics, execution time and the later one is found to be as the best appropriate Rayleigh multipath model suitable for incorporating with GPS simulator. The fading model written in ‘MATLAB’ engine has been linked with software GPS simulator module enable to test GPS receiver’s functionality in different fading environments.

The North American Monsoon GPS Hydrometeorological Network 2017: A New Look at an Old Problem

Science.gov (United States)

Adams, D. K.

2017-12-01

Quantifying moisture recycling and determining water vapor source regions for deep convective precipitation have been problematic, particular in tropical continental regions. More than an academic concern, modeling convective precipitation, from cloud-resolving to global climate models, depends critically on properly representing atmospheric water vapor transport, its vertical distribution, as well as surface latent heat flux contributions. The North American Monsoon region, given its complex topography, proximity to warm oceans, striking vegetation "green up" and oftentimes subtle dynamical forcing is particular challenging in this regard. Recent studies, employing modeling and observational approaches, give a prominent role for moisture recycling in fomenting deep convective precipitation. Likewise, these studies argue for the increased importance of transport from the Gulf of Mexico/Central America and the Atlantic Ocean, relative to the Pacific Ocean/Gulf of California. In this presentation, we critically review these studies which served to motivate the NAM GPS Hydrometeorological Network 2017, detailed here. This bi-national (Mexico-US) 3-month campaign to examine water vapor source regions, and specifically, land-surface water vapor fluxes consists of 10 experimental GPS meteorological sites as well as TLALOCNet and Suominet GPS sites in the Mexican states of Sonora, Chihuahua, Sinaloa, and Baja California and in Arizona and New Mexico. Near Rayón Sonora, inside the larger regional GPSmet array, a 30km eddy covariance flux tower triangular array, with collocated GPSmet, measures continuous energy fluxes and precipitable water vapor. Preliminary results examining the local flux contribution in the triangular array to total precipitable water vapor measured are presented. Further research is then outlined.

GPS User Devices Parameter Control Methods

OpenAIRE

Klūga, A; Kuļikovs, M; Beļinska, V; Zeļenkovs, A

2007-01-01

In our day’s wide assortment of GPS user devices is manufacture. How to verify that parameters of the real device corresponds to parameters that manufacture shows. How to verify that parameters have not been changed during the operation time. The last one is very important for aviation GPS systems, which must be verified before the flight, but the values of parameter in time of repair works. This work analyses GPS user devices parameters control methods.

Solar Energy Campaign. 2008 Norwegian student-based web campaign

Energy Technology Data Exchange (ETDEWEB)

Randall, Scott

2009-07-01

Student research campaigns (forskningskampanjer) have been an annual event in connection to Research Days (Forskningsdagene) since 2003 in Norway. The campaigns invite students from all over the country to participate in a common scientific research event, always connected to a special environmentally related theme - for example Air Quality in the Classroom (2003), Pollution along Roads (2004), Bacteria in Drinking Water (2005), and The Rain Check (2006). The year 2008, as with previous years, was overshadowed by the topic of climate change, and the specific role of humans. The research campaign theme for 2008 fit well into this focus: the potential benefits of solar energy as an alternative energy source. The campaign also was aligned with the Research Days theme of alternative energy sources and technologies. The campaign included the hands-on activity of assembling a solar panel and taking measurements with the device to determine efficiency, as well as a questionnaire to record the results and ask deeper questions regarding alternative energy and climate change. The results gained from data analysis of the campaign show that students were able to gain maximum efficient solar power from the devices they constructed, which gave them a solid understanding of solar power technology. Analysis of the campaign questionnaire in regards to the activity shows that students believe that solar energy should be better utilized as an energy source in Norway. (Also in Norwegian OR 24/2009). (Author)

Investigating the performance of neural network backpropagation algorithms for TEC estimations using South African GPS data

Science.gov (United States)

Habarulema, J. B.; McKinnell, L.-A.

2012-05-01

In this work, results obtained by investigating the application of different neural network backpropagation training algorithms are presented. This was done to assess the performance accuracy of each training algorithm in total electron content (TEC) estimations using identical datasets in models development and verification processes. Investigated training algorithms are standard backpropagation (SBP), backpropagation with weight delay (BPWD), backpropagation with momentum (BPM) term, backpropagation with chunkwise weight update (BPC) and backpropagation for batch (BPB) training. These five algorithms are inbuilt functions within the Stuttgart Neural Network Simulator (SNNS) and the main objective was to find out the training algorithm that generates the minimum error between the TEC derived from Global Positioning System (GPS) observations and the modelled TEC data. Another investigated algorithm is the MatLab based Levenberg-Marquardt backpropagation (L-MBP), which achieves convergence after the least number of iterations during training. In this paper, neural network (NN) models were developed using hourly TEC data (for 8 years: 2000-2007) derived from GPS observations over a receiver station located at Sutherland (SUTH) (32.38° S, 20.81° E), South Africa. Verification of the NN models for all algorithms considered was performed on both "seen" and "unseen" data. Hourly TEC values over SUTH for 2003 formed the "seen" dataset. The "unseen" dataset consisted of hourly TEC data for 2002 and 2008 over Cape Town (CPTN) (33.95° S, 18.47° E) and SUTH, respectively. The models' verification showed that all algorithms investigated provide comparable results statistically, but differ significantly in terms of time required to achieve convergence during input-output data training/learning. This paper therefore provides a guide to neural network users for choosing appropriate algorithms based on the availability of computation capabilities used for research.

Teaching young GPs to cope with psychosocial consultations without prescribing: a durable impact of an e-module on determinants of benzodiazepines prescribing.

Science.gov (United States)

Creupelandt, Hanne; Anthierens, Sibyl; Habraken, Hilde; Declercq, Tom; Sirdifield, Coral; Siriwardena, Aloysius Niroshan; Christiaens, Thierry

2017-12-19

Despite guidelines and campaigns to change prescribing behavior, General Practitioners (GPs) continue to overprescribe benzodiazepines (BZDs). New approaches to improve prescribing are needed. Using behavior change techniques and tailoring interventions to user characteristics are vital to promote behavior change. This study evaluated the impact of an e-module on factors known to determine BZD prescribing practice. A tailored e-module that focuses on avoiding initial BZD prescriptions (and using psychological interventions as an alternative) was developed and offered to GPs in vocational training. Three self-report assessments took place: at baseline, immediately after the module (short term) and at least six months after completion (long term). Assessed determinants include GPs' attitudes concerning treatment options, perceptions of the patient and self-efficacy beliefs. Readiness to adhere to prescribing guidelines was evaluated through assessing motivation, self-efficacy and implementability of non-pharmacological interventions. Changes in determinants were analyzed using the Wilcoxon signed-rank test. Changes in readiness to adhere to guidelines was analyzed using the nonparametric McNemar Bowker test. A desirable, significant and durable impact on determinants of BZD prescribing was observed. GPs (n = 121) underwent desirable changes in their attitudes, perceptions and self-efficacy beliefs and these changes remained significant months after the intervention. Barriers to using a non-pharmacological approach often cited in literature remained absent and were not highlighted by the intervention. Furthermore a significant impact on GPs' readiness to adhere to guidelines was observed. Participants reported change in their ability to cope with psychosocial consultations and to have tried using non-pharmacological interventions. Tailoring an e-intervention to target group (GPs) characteristics appears to be successful in promoting behavioral change in GPs

Analysis of strong ionospheric scintillation events measured by means of GPS signals at low latitudes during disturbed conditions

Science.gov (United States)

Forte, B.

2012-08-01

Drifting structures characterized by inhomogeneities in the spatial electron density distribution at ionospheric heights cause the scintillation of radio waves propagating through. The fractional electron density fluctuations and the corresponding scintillation levels may reach extreme values at low latitudes during high solar activity. Different levels of scintillation were observed on experimental data collected in the Asian sector at low latitudes by means of a GPS dual frequency receiver under moderate solar activity (2005). The GPS receiver used in these campaigns was particularly modified in firmware in order to record power estimates on the C/A code as well as on the carriers L1 and L2. Strong scintillation activity was recorded in the post-sunset period (saturatingS4 and SI as high as 20 dB). Spectral modifications and broadening was observed during high levels of scintillation possibly indicating refractive scattering taking place instead of diffractive scattering. A possible interpretation of those events was attempted on the basis of the refractive scattering theory developed by Uscinski (1968) and Booker and MajidiAhi (1981).

Ionospheric error analysis in gps measurements

Directory of Open Access Journals (Sweden)

G. Pugliano

2008-06-01

Full Text Available The results of an experiment aimed at evaluating the effects of the ionosphere on GPS positioning applications are presented in this paper. Specifically, the study, based upon a differential approach, was conducted utilizing GPS measurements acquired by various receivers located at increasing inter-distances. The experimental research was developed upon the basis of two groups of baselines: the first group is comprised of "short" baselines (less than 10 km; the second group is characterized by greater distances (up to 90 km. The obtained results were compared either upon the basis of the geometric characteristics, for six different baseline lengths, using 24 hours of data, or upon temporal variations, by examining two periods of varying intensity in ionospheric activity respectively coinciding with the maximum of the 23 solar cycle and in conditions of low ionospheric activity. The analysis revealed variations in terms of inter-distance as well as different performances primarily owing to temporal modifications in the state of the ionosphere.

A generalized development model for testing GPS user equipment

Science.gov (United States)

Hemesath, N.

1978-01-01

The generalized development model (GDM) program, which was intended to establish how well GPS user equipment can perform under a combination of jamming and dynamics, is described. The systems design and the characteristics of the GDM are discussed. The performance aspects of the GDM are listed and the application of the GDM to civil aviation is examined.

Multiscale GPS tomography during COPS: validation and applications

Science.gov (United States)

Champollion, Cédric; Flamant, Cyrille; Masson, Frédéric; Gégout, Pascal; Boniface, Karen; Richard, Evelyne

2010-05-01

Accurate 3D description of the water vapour field is of interest for process studies such as convection initiation. None of the current techniques (LIDAR, satellite, radio soundings, GPS) can provide an all weather continuous 3D field of moisture. The combination of GPS tomography with radio-soundings (and/or LIDAR) has been used for such process studies using both advantages of vertically resolved soundings and high temporal density of GPS measurements. GPS tomography has been used at short scale (10 km horizontal resolution but in a 50 km² area) for process studies such as the ESCOMPTE experiment (Bastin et al., 2005) and at larger scale (50 km horizontal resolution) during IHOP_2002. But no extensive statistical validation has been done so far. The overarching goal of the COPS field experiment is to advance the quality of forecasts of orographically induced convective precipitation by four-dimensional observations and modeling of its life cycle for identifying the physical and chemical processes responsible for deficiencies in QPF over low-mountain regions. During the COPS field experiment, a GPS network of about 100 GPS stations has been continuously operating during three months in an area of 500 km² in the East of France (Vosges Mountains) and West of Germany (Black Forest). If the mean spacing between the GPS is about 50 km, an East-West GPS profile with a density of about 10 km is dedicated to high resolution tomography. One major goal of the GPS COPS experiment is to validate the GPS tomography with different spatial resolutions. Validation is based on additional radio-soundings and airborne / ground-based LIDAR measurement. The number and the high quality of vertically resolved water vapor observations give an unique data set for GPS tomography validation. Numerous tests have been done on real data to show the type water vapor structures that can be imaging by GPS tomography depending of the assimilation of additional data (radio soundings), the

The Inversion of Ionospheric/plasmaspheric Electron Density From GPS Beacon Observations

Science.gov (United States)

Zou, Y. H.; Xu, J. S.; Ma, S. Y.

It is a space-time 4-D tomography to reconstruct ionospheric/ plasmaspheric elec- tron density, Ne, from ground-based GPS beacon measurements. The mathematical foundation of such inversion is studied in this paper and some simulation results of reconstruction for GPS network observation are presented. Assuming reasonably a power law dependence of NE on time with an index number of 1-3 during one ob- servational time of GPS (60-90min.), 4-D inversion in consideration is reduced to a 3-D cone-beam tomography with incomplete projections. To see clearly the effects of the incompleteness on the quality of reconstruction for 3-D condition, we deduced theoretically the formulae of 3-D parallel-beam tomography. After establishing the mathematical basis, we adopt linear temporal dependence of NE and voxel elemental functions to perform simulation of NE reconstruction with the help of IRI90 model. Reasonable time-dependent 3-D images of ionosphere/ plasmasphere electron density distributions are obtained when taking proper layout of the GPS network and allowing variable resolutions in vertical.

An improved grey model for the prediction of real-time GPS satellite clock bias

Science.gov (United States)

Zheng, Z. Y.; Chen, Y. Q.; Lu, X. S.

2008-07-01

In real-time GPS precise point positioning (PPP), real-time and reliable satellite clock bias (SCB) prediction is a key to implement real-time GPS PPP. It is difficult to hold the nuisance and inenarrable performance of space-borne GPS satellite atomic clock because of its high-frequency, sensitivity and impressionable, it accords with the property of grey model (GM) theory, i. e. we can look on the variable process of SCB as grey system. Firstly, based on limits of quadratic polynomial (QP) and traditional GM to predict SCB, a modified GM (1,1) is put forward to predict GPS SCB in this paper; and then, taking GPS SCB data for example, we analyzed clock bias prediction with different sample interval, the relationship between GM exponent and prediction accuracy, precision comparison of GM to QP, and concluded the general rule of different type SCB and GM exponent; finally, to test the reliability and validation of the modified GM what we put forward, taking IGS clock bias ephemeris product as reference, we analyzed the prediction precision with the modified GM, It is showed that the modified GM is reliable and validation to predict GPS SCB and can offer high precise SCB prediction for real-time GPS PPP.

Campaigning on behalf of the party? Party constraints on candidate campaign personalisation

DEFF Research Database (Denmark)

Bøggild, Troels; Pedersen, Helene Helboe

2017-01-01

This article analyses what makes political candidates run a party-focused or personalised election campaign. Prior work shows that candidates face incentives from voters and the media to personalise their campaign rhetoric and promises at the expense of party policy. This has raised concerns about...... that party control over the candidate nomination process and campaign financing constrains most political candidates in following electoral incentives for campaign personalisation. Using candidate survey data from the 2009 EP election campaign in 27 countries, we show how candidates from parties in which...... party officials exerted greater control over the nomination process and campaign finances were less likely to engage in personalised campaigning at the expense of the party programme. The findings imply that most parties, as central gatekeepers and resource suppliers, hold important control mechanisms...

Sounding rocket/ground-based observation campaign to study Medium-Scale Traveling Ionospheric Disturbances (MSTID)

Science.gov (United States)

Yamamoto, M.; Yokoyama, T.; Saito, A.; Otsuka, Y.; Yamamoto, M.; Abe, T.; Watanabe, S.; Ishisaka, K.; Saito, S.; Larsen, M.; Pfaff, R. F.; Bernhardt, P. A.

2012-12-01

An observation campaign is under preparation. It is to launch sounding rockets S-520-27 and S-310-42 from Uchinoura Space Center of JAXA while ground-based instruments measure waves in the ionosphere. It is scheduled in July/August 2013. The main purpose of the experiment is to reveal generation mechanism of Medium-Scale Traveling Ionospheric Disturbance (MSTID). The MSTID is the ionospheric wave with 1-2 hour periodicity, 100-200 km horizontal wavelength, and southwestward propagation. It is enhanced in the summer nighttime of the mid-latitude ionosphere. The MSTID is not only a simple atmospheric-wave modulation of the ionosphere, but shows similarity to characteristics of the Perkins instability. A problem is that growth rate of the Perkins instability is too small to explain the phenomena. We now hypothesize a generation mechanism that electromagnetic coupling of the F- and E-regions help rapid growth of the MSTID especially at its initial stage. In the observation campaign, we will use the sounding rocket S-520-27 for in-situ measurement of ionospheric parameters, i.e., electron density and electric fields. Wind velocity measurements in both F- and E-regions are very important as well. For the F-region winds, we will conduct Lithium-release experiment under the full-moon condition. This is a big technical challenge. Another rocket S-310-42 will be used for the E-region wind measurement with the TMA release. On the ground, we will use GEONET (Japanese vast GPS receiver network) to monitor horizontal distribution of GPS-TEC on the realtime bases. In the presentation we will show MSTID characteristics and the proposed generation mechanism, and discuss plan and current status of the project.

Relative navigation and attitude determination using a GPS/INS integrated system near the International Space Station

Science.gov (United States)

Um, Jaeyong

2001-08-01

The Space Integrated GPS/INS (SIGI) sensor is the primary navigation and attitude determination source for the International Space Station (ISS). The SIGI was successfully demonstrated on-orbit for the first time in the SIGI Orbital Attitude Readiness (SOAR) demonstration on the Space Shuttle Atlantis in May 2000. Numerous proximity operations near the ISS have been and will be performed over the lifetime of the Station. The development of an autonomous relative navigation system is needed to improve the safety and efficiency of vehicle operations near the ISS. A hardware simulation study was performed for the GPS-based relative navigation using the state vector difference approach and the interferometric approach in the absence of multipath. The interferometric approach, where the relative states are estimated directly, showed comparable results for a 1 km baseline. One of the most pressing current technical issues is the design of an autonomous relative navigation system in the proximity of the ISS, where GPS signals are blocked and maneuvers happen frequently. An integrated GPS/INS system is investigated for the possibility of a fully autonomous relative navigation system. Another application of GPS measurements is determination of the vehicle's orientation in space. This study used the SOAR experiment data to characterize the SICI's on-orbit performance for attitude determination. A cold start initialization algorithm was developed for integer ambiguity resolution in any initial orientation. The original algorithm that was used in the SIGI had an operational limitation in the integer ambiguity resolution, which was developed for terrestrial applications, and limited its effectiveness in space. The new algorithm was tested using the SOAR data and has been incorporated in the current SIGI flight software. The attitude estimation performance was examined using two different GPS/INS integration algorithms. The GPS/INS attitude solution using the SOAR data was as

Briefing highlights space weather risks to GPS

Science.gov (United States)

Tretkoff, Ernie

2011-07-01

Solar storms, which are expected to increase as the Sun nears the most active phase of the solar cycle, can disrupt a variety of technologies on which society relies. Speakers at a 22 June briefing on Capitol Hill in Washington, D. C., focused on how space weather can affect the Global Positioning System (GPS), which is used in a wide range of industries, including commercial air travel, agriculture, national security, and emergency response. Rocky Stone, chief technical pilot for United Airlines, noted that GPS allows more aircraft to be in airspace, saves fuel, and helps aircraft move safely on runways. “Improvements in space weather forecasting need to be pursued,” he said. Precision GPS has also “changed the whole nature of farming,” said Ron Hatch, Director of Navigation Systems, NavCom Technology/John Deere. GPS makes it possible for tractors to be driven in the most efficient paths and for fertilizer and water to be applied precisely to the areas that most need them. Space weather-induced degradation of GPS signals can cause significant loss to farms that rely on GPS. Elizabeth Zimmerman, Deputy Associate Administrator for the Office of Response and Recovery at the Federal Emergency Management Agency (FEMA), described how FEMA relies on GPS for disaster recovery. The agency is developing an operations plan for dealing with space weather, she said.

Development of GPS survey data management protocols/policy.

Science.gov (United States)

2010-08-01

This project developed a statewide policy and criteria for collecting, analyzing, and managing global position system (GPS) survey data. The research project determined the needs of the Department in adopting the GPS real time kinetic (GPS RTK) stake...

GPS Usage in a Population of Low-Vision Drivers.

Science.gov (United States)

Cucuras, Maria; Chun, Robert; Lee, Patrick; Jay, Walter M; Pusateri, Gregg

2017-01-01

We surveyed bioptic and non-bioptic low-vision drivers in Illinois, USA, to determine their usage of global positioning system (GPS) devices. Low-vision patients completed an IRB-approved phone survey regarding driving demographics and usage of GPS while driving. Participants were required to be active drivers with an Illinois driver's license, and met one of the following criteria: best-corrected visual acuity (BCVA) less than or equal to 20/40, central or significant peripheral visual field defects, or a combination of both. Of 27 low-vision drivers, 10 (37%) used GPS while driving. The average age for GPS users was 54.3 and for non-users was 77.6. All 10 drivers who used GPS while driving reported increased comfort or safety level. Since non-GPS users were significantly older than GPS users, it is likely that older participants would benefit from GPS technology training from their low-vision eye care professionals.

Status of Precise Orbit Determination for Jason-2 Using GPS

Science.gov (United States)

Melachroinos, S.; Lemoine, F. G.; Zelensky, N. P.; Rowlands, D. D.; Pavlis, D. E.

2011-01-01

The JASON-2 satellite, launched in June 2008, is the latest follow-on to the successful TOPEX/Poseidon (T/P) and JASON-I altimetry missions. JASON-2 is equipped with a TRSR Blackjack GPS dual-frequency receiver, a laser retroreflector array, and a DORIS receiver for precise orbit determination (POD). The most recent time series of orbits computed at NASA GSFC, based on SLR/DORIS data have been completed using both ITRF2005 and ITRF2008. These orbits have been shown to agree radially at 1 cm RMS for dynamic vs SLRlDORIS reduced-dynamic orbits and in comparison with orbits produced by other analysis centers (Lemoine et al., 2010; Zelensky et al., 2010; Cerri et al., 2010). We have recently upgraded the GEODYN software to implement model improvements for GPS processing. We describe the implementation of IGS standards to the Jason2 GEODYN GPS processing, and other dynamical and measurement model improvements. Our GPS-only JASON-2 orbit accuracy is assessed using a number of tests including analysis of independent SLR and altimeter crossover residuals, orbit overlap differences, and direct comparison to orbits generated at GSFC using SLR and DORIS tracking, and to orbits generated externally at other centers. Tests based on SLR and the altimeter crossover residuals provide the best performance indicator for independent validation of the NASAlGSFC GPS-only reduced dynamic orbits. For the ITRF2005 and ITRF2008 implementation of our GPS-only obits we are using the IGS05 and IGS08 standards. Reduced dynamic versus dynamic orbit differences are used to characterize the remaining force model error and TRF instability. We evaluate the GPS vs SLR & DORIS orbits produced using the GEODYN software and assess in particular their consistency radially and the stability of the altimeter satellite reference frame in the Z direction for both ITRF2005 and ITRF2008 as a proxy to assess the consistency of the reference frame for altimeter satellite POD.

Transportation mode recognition using GPS and accelerometer data

NARCIS (Netherlands)

Feng, T.; Timmermans, H.J.P.

2013-01-01

Potential advantages of global positioning systems (GPS) in collecting travel behavior data have been discussed in several publications and evidenced in many recent studies. Most applications depend on GPS information only. However, transportation mode detection that relies only on GPS information

Gestió mapes i GPS

OpenAIRE

Díaz Sañudo, Daniel

2013-01-01

El projecte denominat "Gestor de mapes i GPS" és una aplicació per a dispositius mòbils Android que utilitza l'API v.1 de Google Maps. El proyecto denominado "Gestor de mapas y GPS" es una aplicación para dispositivos móviles Android que utiliza la API v.1 de Google Maps.

Location - Global Positioning System (GPS) Photos

Data.gov (United States)

Army Corps of Engineers, Department of the Army, Department of Defense — Digital photos tagged with GPS location information. The St. Paul District maintains a digital library of over 10,000 GPS photos. Photos are often associated with...

The African American Women and Mass Media (AAMM) campaign in Georgia: quantifying community response to a CDC pilot campaign.

Science.gov (United States)

Hall, Ingrid J; Johnson-Turbes, Ashani; Berkowitz, Zahava; Zavahir, Yasmine

2015-05-01

To evaluate whether a culturally appropriate campaign using "Black radio" and print media increased awareness and utilization of local mammography screening services provided by the Centers for Disease Control and Prevention's National Breast and Cervical Cancer Early Detection Program among African American women. The evaluation used a quasi-experimental design involving data collection during and after campaign implementation in two intervention sites in GA (Savannah with radio and print media and Macon with radio only) and one comparison site (Columbus, GA). We used descriptive statistics to compare mammography uptake for African American women during the initial months of the campaign (8/08-1/09) with the latter months (2/09-8/09) and a post-campaign (9/09-12/09) period in each of the study sites. Comparisons of monthly mammogram uptake between cities were performed with multinomial logistic regression. We assumed a p value campaign to the later period. However, the increase did not persist in the post-campaign period. Analysis comparing monthly mammogram uptake in Savannah and Macon with Columbus showed a significant increase in uptake from the first to the second period in Savannah only (OR 1.269, 95 % CI (1.005-1.602), p = 0.0449). Dissemination of health promotion messages via a culturally appropriate, multicomponent campaign using Black radio and print media was effective in increasing mammogram uptake in Savannah among low-income, African American women. Additional research is needed to quantify the relative contribution of campaign radio, print media, and community components to sustain increased mammography uptake.

Comparison of GLONASS and GPS Time Transfers

Science.gov (United States)

Daly, P.; Koshelyaevsky, N. B.; Lewandowski, W.; Petit, G.; Thomas, C.

1993-01-01

The Russian global space navigation system GLONASS could provide a technique similar to GPS for international time comparison. The main limitation to its use for time transfer is the lack of commercially available time receivers. The University of Leeds built a GPS/GLONASS receiver five years ago and since then has provided continuous information about GLONASS time and its comparison with GPS time. For the last two years the VNIIFTRI and several other Russian time laboratories have used Russian-built GLONASS navigation receivers for time comparisons. Since June 1991, the VNIIFTRI has operated a GPS time receiver which offers, for the first time, an opportunity for the direct comparison of time transfers using GPS and GLONASS. This seven-month experiment shows that even with relatively imprecise data recording and processing, in terms of time metrology, GLONASS can provide continental time transfer at a level of several tens of nanoseconds.

[Do general practitioners in Geneva (Switzerland) and Poitou-Charentes (France) have different approach to the management of addictions?].

Science.gov (United States)

Teoli, Romain; Haller, Dagmar M; Ingrand, Pierre; Binder, Philippe

2016-01-01

Addiction care is mostly provided by general practitioners (GPs) but the extent of their involvement is variable. Is this related to different training or practice contexts or to awareness campaigns? To study GPs' views and behaviours in relation to addiction patients in different practice and training contexts and different levels of exposure to awareness campaigns. Cross-sectional postal survey involving 526 GPs from the canton of Geneva, Switzerland, sensitized by specific addiction care campaigns, compared to 628 GPs from two rural Departments of Poitou-Charentes, France, not exposed to this type of awareness campaign. The response rate was 46% in Switzerland and 41% in France. The 243 responding GPs in Geneva saw as many patients with tobacco, alcohol, cannabis or opiate addiction as the 256 GPs in Poitou-Charentes. They shared similar views concerning their roles in relation to these addictions. Compared to Swiss GPs, a significantly higher number of French GPs provided first-line care for tobacco addiction. In both countries, care for addiction to other substances was mostly provided in collaboration with a specialist (>75% of cases). GPs in Geneva attributed greater importance to screening and recording of substance use. They were also more involved in training and in providing brief advice and expressed interest in the network. Awareness campaigns in Geneva could explain these differences. Sensitization of GPs to these issues may contribute to modifying certain professional attitudes, regardless of the context.

Continuing medical education and burnout among Danish GPs

DEFF Research Database (Denmark)

Brøndt, Anders; Sokolowski, Ineta; Olesen, Frede

2008-01-01

BACKGROUND: There has been minimal research into continuing medical education (CME) and its association with burnout among GPs. AIM: The aim of this study was to investigate the association between participating in CME and experiencing burnout in a sample of Danish GPs. DESIGN OF STUDY: Cross......-sectional questionnaire study. SETTING: All 458 active GPs in 2004, in the County of Aarhus, Denmark were invited to participate. METHOD: Data on CME activities were obtained for all GPs and linked to burnout which was measured using the Maslach Burnout Inventory - Human Services Survey. The relationship between CME...... activity and burnout was calculated as prevalence ratios (PR) in a generalised linear model. RESULTS: In total, 379 (83.5%) GPs returned the questionnaire. The prevalence of burnout was about 25%, and almost 3% suffered from 'high burnout'. A total of 344 (92.0%) GPs were members of a CME group...

Development And Test of A Digitally Steered Antenna Array for The Navigator GPS Receiver

Science.gov (United States)

Pinto, Heitor David; Valdez, Jennifer E.; Winternitz, Luke M. B.; Hassouneh, Munther A.; Price, Samuel R.

2012-01-01

Global Positioning System (GPS)-based navigation has become common for low-Earth orbit spacecraft as the signal environment is similar to that on the Earth s surface. The situation changes abruptly, however, for spacecraft whose orbital altitudes exceed that of the GPS constellation. Visibility is dramatically reduced and signals that are present may be very weak and more susceptible to interference. GPS receivers effective at these altitudes require increased sensitivity, which often requires a high-gain antenna. Pointing such an antenna can pose a challenge. One efficient approach to mitigate these problems is the use of a digitally steered antenna array. Such an antenna can optimally allocate gain toward desired signal sources and away from interferers. This paper presents preliminary results in the development and test of a digitally steered antenna array for the Navigator GPS research program at NASA s Goddard Space Flight Center. In particular, this paper highlights the development of an array and front-end electronics, the development and test of a real-time software GPS receiver, and implementation of three beamforming methods for combining the signals from the array. Additionally, this paper discusses the development of a GPS signal simulator which produces digital samples of the GPS L1C/A signals as they would be received by an arbitrary antenna array configuration. The simulator models transmitter and receiver dynamics, near-far and multipath interference, and has been a critical component in both the development and test of the GPS receiver. The GPS receiver system was tested with real and simulated GPS signals. Preliminary results show that performance improvement was achieved in both the weak signal and interference environments, matching analytical predictions. This paper summarizes our initial findings and discusses the advantages and limitations of the antenna array and the various beamforming methods.

Comparative Analysis of GPS Clock Performance Using Both Code-Phase and Carrier-Derived Pseudorange Observations

National Research Council Canada - National Science Library

Oaks, Jay; Largay, Marie M; Reid, Wilson G; Buisson, James A

2004-01-01

The Naval Research Laboratory (NRL) has, for many years, determined the GPS space vehicle clock offsets by differencing the pseudorange observations and the post-fit orbit provided by the National Geospatial-Intelligence Agency (NGA...

GPS Tomography: Water Vapour Monitoring for Germany

Science.gov (United States)

Bender, Michael; Dick, Galina; Wickert, Jens; Raabe, Armin

2010-05-01

Ground based GPS atmosphere sounding provides numerous atmospheric quantities with a high temporal resolution for all weather conditions. The spatial resolution of the GPS observations is mainly given by the number of GNSS satellites and GPS ground stations. The latter could considerably be increased in the last few years leading to more reliable and better resolved GPS products. New techniques such as the GPS water vapour tomography gain increased significance as data from large and dense GPS networks become available. The GPS tomography has the potential to provide spatially resolved fields of different quantities operationally, i. e. the humidity or wet refractivity as required for meteorological applications or the refraction index which is important for several space based observations or for precise positioning. The number of German GPS stations operationally processed by the GFZ in Potsdam was recently enlarged to more than 300. About 28000 IWV observations and more than 1.4 millions of slant total delay data are now available per day with a temporal resolution of 15 min and 2.5 min, respectively. The extended network leads not only to a higher spatial resolution of the tomographically reconstructed 3D fields but also to a much higher stability of the inversion process and with that to an increased quality of the results. Under these improved conditions the GPS tomography can operate continuously over several days or weeks without applying too tight constraints. Time series of tomographically reconstructed humidity fields will be shown and different initialisation strategies will be discussed: Initialisation with a simple exponential profile, with a 3D humidity field extrapolated from synoptic observations and with the result of the preceeding reconstruction. The results are compared to tomographic reconstructions initialised with COSMO-DE analyses and to the corresponding model fields. The inversion can be further stabilised by making use of independent

A RLS-SVM Aided Fusion Methodology for INS during GPS Outages.

Science.gov (United States)

Yao, Yiqing; Xu, Xiaosu

2017-02-24

In order to maintain a relatively high accuracy of navigation performance during global positioning system (GPS) outages, a novel robust least squares support vector machine (LS-SVM)-aided fusion methodology is explored to provide the pseudo-GPS position information for the inertial navigation system (INS). The relationship between the yaw, specific force, velocity, and the position increment is modeled. Rather than share the same weight in the traditional LS-SVM, the proposed algorithm allocates various weights for different data, which makes the system immune to the outliers. Field test data was collected to evaluate the proposed algorithm. The comparison results indicate that the proposed algorithm can effectively provide position corrections for standalone INS during the 300 s GPS outage, which outperforms the traditional LS-SVM method. Historical information is also involved to better represent the vehicle dynamics.

A RLS-SVM Aided Fusion Methodology for INS during GPS Outages

Directory of Open Access Journals (Sweden)

Yiqing Yao

2017-02-01

Full Text Available In order to maintain a relatively high accuracy of navigation performance during global positioning system (GPS outages, a novel robust least squares support vector machine (LS-SVM-aided fusion methodology is explored to provide the pseudo-GPS position information for the inertial navigation system (INS. The relationship between the yaw, specific force, velocity, and the position increment is modeled. Rather than share the same weight in the traditional LS-SVM, the proposed algorithm allocates various weights for different data, which makes the system immune to the outliers. Field test data was collected to evaluate the proposed algorithm. The comparison results indicate that the proposed algorithm can effectively provide position corrections for standalone INS during the 300 s GPS outage, which outperforms the traditional LS-SVM method. Historical information is also involved to better represent the vehicle dynamics.

Impact of a high density GPS network on the operational forecast

Directory of Open Access Journals (Sweden)

C. Faccani

2005-01-01

Full Text Available Global Positioning System Zenith Total Delay (GPS ZTD can provide information about the water vapour in atmosphere. Its assimilation into the analysis used to initialize a model can then improve the weather forecast, giving the right amount of moisture and reducing the model spinup. In the last year, an high density GPS network has been created on the Basilicata region (south of Italy by the Italian Space Agency in the framework of a national project named MAGIC2. MAGIC2 is the Italian follow on of the EC project MAGIC has. Daily operational data assimilation experiments are performed since December 2003. The results show that the assimilation of GPS ZTD improves the forecast especially during the transition from winter to spring even if a no very high model resolution (9km is used.

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

Science.gov (United States)

Wu, Jun; Jiang, Chengsheng; Houston, Douglas; Baker, Dean; Delfino, Ralph

2011-11-14

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

Accurate Localization of Communicant Vehicles using GPS and Vision Systems

Directory of Open Access Journals (Sweden)

Georges CHALLITA

2009-07-01

Full Text Available The new generation of ADAS systems based on cooperation between vehicles can offer serious perspectives to the road security. The inter-vehicle cooperation is made possible thanks to the revolution in the wireless mobile ad hoc network. In this paper, we will develop a system that will minimize the imprecision of the GPS used to car tracking, based on the data given by the GPS which means the coordinates and speed in addition to the use of the vision data that will be collected from the loading system in the vehicle (camera and processor. Localization information can be exchanged between the vehicles through a wireless communication device. The creation of the system must adopt the Monte Carlo Method or what we call a particle filter for the treatment of the GPS data and vision data. An experimental study of this system is performed on our fleet of experimental communicating vehicles.

Florida's "truth" campaign: a counter-marketing, anti-tobacco media campaign.

Science.gov (United States)

Zucker, D; Hopkins, R S; Sly, D F; Urich, J; Kershaw, J M; Solari, S

2000-05-01

The "truth" campaign was created to change youth attitudes about tobacco and to reduce teen tobacco use throughout Florida by using youth-driven advertising, public relations, and advocacy. Results of the campaign include a 92 percent brand awareness rate among teens, a 15 percent rise in teens who agree with key attitudinal statements about smoking, a 19.4 percent decline in smoking among middle school students, and a 8.0 percent decline among high school students. States committed to results-oriented youth anti-tobacco campaigns should look to Florida's "truth" campaign as a model that effectively places youth at the helm of anti-tobacco efforts.

GPS Test Facility

Data.gov (United States)

Federal Laboratory Consortium — The Global Positioning System (GPS) Test Facility Instrumentation Suite (GPSIS) provides great flexibility in testing receivers by providing operational control of...

The use of radiological guidelines to achieve a sustained reduction in the number of radiographic examinations of the cervical spine, lumbar spine and knees performed for GPs

International Nuclear Information System (INIS)

Glaves, J.

2005-01-01

AIM: To determine if the use of request guidelines can achieve a sustained reduction in the number of radiographic examinations of the cervical spine, lumbar spine and knee joints performed for general practitioners (GPs). METHODS: GPs referring to three community hospitals and a district general hospital were circulated with referral guidelines for radiography of the cervical spine, lumbar spine and knee, and all requests for these three examinations were checked. Requests that did not fit the guidelines were returned to the GP with an explanatory letter and a further copy of the guidelines. Where applicable, a large-joint replacement algorithm was also enclosed. If the GP maintained the opinion that the examination was indicated, she or he had the option of supplying further justifying information in writing or speaking to a consultant radiologist. RESULTS: Overall the number of radiographic examinations fell by 68% in the first year, achieving a 79% reduction in the second year. For knees, lumbar spine and cervical spine radiographs the total reductions were 77%, 78% and 86%, respectively. CONCLUSION: The use of referral guidelines, reinforced by request checking and clinical management algorithms, can produce a dramatic and sustained reduction in the number of radiographs of the cervical spine, lumbar spine and knees performed for GPs

Uav Onboard Photogrammetry and GPS Positionning for Earthworks

Science.gov (United States)

Daakir, M.; Pierrot-Deseilligny, M.; Bosser, P.; Pichard, F.; Thom, C.

2015-08-01

Over the last decade, Unmanned Airbone Vehicles (UAVs) have been largely used for civil applications. Airborne photogrammetry has found place in these applications not only for 3D modeling but also as a measurement tool. Vinci-Construction-Terrassement is a private company specialized in public works sector and uses airborn photogrammetry as a mapping solution and metrology investigation tool on its sites. This technology is very efficient for the calculation of stock volumes for instance, or for time tracking of specific areas with risk of landslides. The aim of the present work is to perform a direct georeferencing of images acquired by the camera leaning on an embedded GPS receiver. UAV, GPS receiver and camera used are low-cost models and therefore data processing is adapted to this particular constraint.

What determines the income gap between French male and female GPs - the role of medical practices

Directory of Open Access Journals (Sweden)

Dumontet Magali

2012-09-01

Full Text Available Abstract Background In many OECD countries, the gender differences in physicians’ pay favour male doctors. Due to the feminisation of the doctor profession, it is essential to measure this income gap in the French context of Fee-for-service payment (FFS and then to precisely identify its determinants. The objective of this study is to measure and analyse the 2008 income gap between males and females general practitioners (GPs. This paper focuses on the role of gender medical practices differentials among GPs working in private practice in the southwest region of France. Methods Using data from 339 private-practice GPs, we measured an average gender income gap of approximately 26% in favour of men. Using the decomposition method, we examined the factors that could explain gender disparities in income. Results The analysis showed that 73% of the income gap can be explained by the average differences in doctors’ characteristics; for example, 61% of the gender income gap is explained by the gender differences in workload, i.e., number of consultations and visits, which is on average significantly lower for female GPs than for male GPs. Furthermore, the decomposition method allowed us to highlight the differences in the marginal returns of doctors’ characteristics and variables contributing to income, such as GP workload; we found that female GPs have a higher marginal return in terms of earnings when performing an additional medical service. Conclusions The findings of this study help to understand the determinants of the income gap between male and female GPs. Even though workload is clearly an essential determinant of income, FFS does not reduce the gender income gap, and there is an imperfect relationship between the provision of medical services and income. In the context of feminisation, it appears that female GPs receive a lower income but attain higher marginal returns when performing an additional consultation.

What determines the income gap between French male and female GPs - the role of medical practices.

Science.gov (United States)

Dumontet, Magali; Le Vaillant, Marc; Franc, Carine

2012-09-21

In many OECD countries, the gender differences in physicians' pay favour male doctors. Due to the feminisation of the doctor profession, it is essential to measure this income gap in the French context of Fee-for-service payment (FFS) and then to precisely identify its determinants. The objective of this study is to measure and analyse the 2008 income gap between males and females general practitioners (GPs). This paper focuses on the role of gender medical practices differentials among GPs working in private practice in the southwest region of France. Using data from 339 private-practice GPs, we measured an average gender income gap of approximately 26% in favour of men. Using the decomposition method, we examined the factors that could explain gender disparities in income. The analysis showed that 73% of the income gap can be explained by the average differences in doctors' characteristics; for example, 61% of the gender income gap is explained by the gender differences in workload, i.e., number of consultations and visits, which is on average significantly lower for female GPs than for male GPs. Furthermore, the decomposition method allowed us to highlight the differences in the marginal returns of doctors' characteristics and variables contributing to income, such as GP workload; we found that female GPs have a higher marginal return in terms of earnings when performing an additional medical service. The findings of this study help to understand the determinants of the income gap between male and female GPs. Even though workload is clearly an essential determinant of income, FFS does not reduce the gender income gap, and there is an imperfect relationship between the provision of medical services and income. In the context of feminisation, it appears that female GPs receive a lower income but attain higher marginal returns when performing an additional consultation.

Fuzzy adaptive integration scheme for low-cost SINS/GPS navigation system

Science.gov (United States)

Nourmohammadi, Hossein; Keighobadi, Jafar

2018-01-01

Due to weak stand-alone accuracy as well as poor run-to-run stability of micro-electro mechanical system (MEMS)-based inertial sensors, special approaches are required to integrate low-cost strap-down inertial navigation system (SINS) with global positioning system (GPS), particularly in long-term applications. This paper aims to enhance long-term performance of conventional SINS/GPS navigation systems using a fuzzy adaptive integration scheme. The main concept behind the proposed adaptive integration is the good performance of attitude-heading reference system (AHRS) in low-accelerated motions and its degradation in maneuvered or accelerated motions. Depending on vehicle maneuvers, gravity-based attitude angles can be intelligently utilized to improve orientation estimation in the SINS. Knowledge-based fuzzy inference system is developed for decision-making between the AHRS and the SINS according to vehicle maneuvering conditions. Inertial measurements are the main input data of the fuzzy system to determine the maneuvering level during the vehicle motions. Accordingly, appropriate weighting coefficients are produced to combine the SINS/GPS and the AHRS, efficiently. The assessment of the proposed integrated navigation system is conducted via real data in airborne tests.

Contents of GPS Data Files

Energy Technology Data Exchange (ETDEWEB)

Sullivan, John P. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Carver, Matthew Robert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Norman, Benjamin [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-12-09

There are no very detailed descriptions of most of these instruments in the literature – we will attempt to fix that problem in the future. The BDD instruments are described in [1]. One of the dosimeter instruments on CXD boxes is described in [2]. These documents (or web links to them) and a few others are in this directory tree. The cross calibration of the CXD electron data with RBSP is described in [3]. Each row in the data file contains the data from one time bin from a CXD or BDD instrument along with a variety of parameters derived from the data. Time steps are commandable but 4 minutes is a typical setting. These instruments are on many (but not all) GPS satellites which are currently in operation. The data come from either BDD instruments on GPS Block IIR satellites (SVN41 and 48), or else CXD-IIR instruments on GPS Block IIR and IIR-M satellites (SVN53-61) or CXD-IIF instruments on GPS block IIF satellites (SVN62-73). The CXD-IIR instruments on block IIR and IIR(M) satellites use the same design.

Why GPS makes distances bigger than they are.

Science.gov (United States)

Ranacher, Peter; Brunauer, Richard; Trutschnig, Wolfgang; Van der Spek, Stefan; Reich, Siegfried

2016-02-01

Global navigation satellite systems such as the Global Positioning System (GPS) is one of the most important sensors for movement analysis. GPS is widely used to record the trajectories of vehicles, animals and human beings. However, all GPS movement data are affected by both measurement and interpolation errors. In this article we show that measurement error causes a systematic bias in distances recorded with a GPS; the distance between two points recorded with a GPS is - on average - bigger than the true distance between these points. This systematic 'overestimation of distance' becomes relevant if the influence of interpolation error can be neglected, which in practice is the case for movement sampled at high frequencies. We provide a mathematical explanation of this phenomenon and illustrate that it functionally depends on the autocorrelation of GPS measurement error ( C ). We argue that C can be interpreted as a quality measure for movement data recorded with a GPS. If there is a strong autocorrelation between any two consecutive position estimates, they have very similar error. This error cancels out when average speed, distance or direction is calculated along the trajectory. Based on our theoretical findings we introduce a novel approach to determine C in real-world GPS movement data sampled at high frequencies. We apply our approach to pedestrian trajectories and car trajectories. We found that the measurement error in the data was strongly spatially and temporally autocorrelated and give a quality estimate of the data. Most importantly, our findings are not limited to GPS alone. The systematic bias and its implications are bound to occur in any movement data collected with absolute positioning if interpolation error can be neglected.

Integration of GPS precise point positioning and MEMS-based INS using unscented particle filter.

Science.gov (United States)

Abd Rabbou, Mahmoud; El-Rabbany, Ahmed

2015-03-25

Integration of Global Positioning System (GPS) and Inertial Navigation System (INS) integrated system involves nonlinear motion state and measurement models. However, the extended Kalman filter (EKF) is commonly used as the estimation filter, which might lead to solution divergence. This is usually encountered during GPS outages, when low-cost micro-electro-mechanical sensors (MEMS) inertial sensors are used. To enhance the navigation system performance, alternatives to the standard EKF should be considered. Particle filtering (PF) is commonly considered as a nonlinear estimation technique to accommodate severe MEMS inertial sensor biases and noise behavior. However, the computation burden of PF limits its use. In this study, an improved version of PF, the unscented particle filter (UPF), is utilized, which combines the unscented Kalman filter (UKF) and PF for the integration of GPS precise point positioning and MEMS-based inertial systems. The proposed filter is examined and compared with traditional estimation filters, namely EKF, UKF and PF. Tightly coupled mechanization is adopted, which is developed in the raw GPS and INS measurement domain. Un-differenced ionosphere-free linear combinations of pseudorange and carrier-phase measurements are used for PPP. The performance of the UPF is analyzed using a real test scenario in downtown Kingston, Ontario. It is shown that the use of UPF reduces the number of samples needed to produce an accurate solution, in comparison with the traditional PF, which in turn reduces the processing time. In addition, UPF enhances the positioning accuracy by up to 15% during GPS outages, in comparison with EKF. However, all filters produce comparable results when the GPS measurement updates are available.

Assessing fitness for work: GPs judgment making.

Science.gov (United States)

Foley, Michelle; Thorley, Kevan; Van Hout, Marie-Claire

2013-12-01

The complexity of a fitness for work consultation is well documented. General practitioners (GPs) find that such consultations often create conflict and they feel ill-prepared for the task. We aimed to examine the consultation process in the fitness for work consultation and to report on the response of GPs to two hypothetical consultations of work related sickness absence, one of a psychological and one of a physical nature. Three areas of the consultation were examined; social/family circumstances, workplace history and information required assessing the severity of the condition. We used a randomized design using an online questionnaire completed by 62 GPs located in the Republic of Ireland. Analysis was conducted in NVivo 8 qualitative software using thematic and content analysis techniques. GPs may be expected to collect and consider information relating to social, domestic, financial, lifestyle and workplace factors, including workload, job satisfaction, job strain, work ethic, inter staff relationships and employee support mechanisms. The mode of presentation may trigger specific information seeking in the consultation. GPs may evaluate fitness for work in a variety of ways depending on medical and non-medical factors. Further research should further examine the factors that may influence the GPs decision to prescribe sickness leave.

Estimation of Sea Level variations with GPS/GLONASS-Reflectometry Technique: Case Study at Stationary Oceanographic Platform in the Black Sea

Science.gov (United States)

Kurbatov, G. A.; Padokhin, A. M.

2017-12-01

In the present work we study GNSS - reflectometry methods for estimation of sea level variations using a single GNSS-receiver, which are based on the multipath propagation effects (interference pattern in SNR of GNSS signals at small elevation angles) caused by the reflection of navigational signals from the sea surface. The measurements were carried out in the coastal zone of Black Sea at the Stationary Oceanographic Platform during one-week campaign in the summer 2017. GPS/GLONASS signals at two working frequencies of both systems were used to study sea level variations which almost doubled the amount of observations compared to GPS-only tide gauge. Moreover all the measurements were conducted with 4-antenna GNSS receiver providing the opportunity for different orientations of antennas including zenith and nadir looking ones as well as two horizontally oriented ones at different azimuths. As the reference we used data from co-located wire wave gauge which showed good correspondence of both datasets. Though tidal effects are not so pronounced for the Black Sea, the described experimental setup allowed to study the effects of sea surface roughness, driven by meteorological conditions (e.g. wind waves), as well as antenna directivity pattern effects on the observed interference patterns of GPS/GLONASS L1/L2 signals (relation of the main spectral peak to the noise power) and the quality of sea level estimations.

GPS Modeling and Analysis. Summary of Research: GPS Satellite Axial Ratio Predictions

Science.gov (United States)

Axelrad, Penina; Reeh, Lisa

2002-01-01

This report outlines the algorithms developed at the Colorado Center for Astrodynamics Research to model yaw and predict the axial ratio as measured from a ground station. The algorithms are implemented in a collection of Matlab functions and scripts that read certain user input, such as ground station coordinates, the UTC time, and the desired GPS (Global Positioning System) satellites, and compute the above-mentioned parameters. The position information for the GPS satellites is obtained from Yuma almanac files corresponding to the prescribed date. The results are displayed graphically through time histories and azimuth-elevation plots.

"We're certainly not in our comfort zone": a qualitative study of GPs' dementia-care educational needs.

Science.gov (United States)

Foley, Tony; Boyle, Siobhán; Jennings, Aisling; Smithson, W Henry

2017-05-22

Rising dementia prevalence rates rise combined with the policy objective of enabling people with dementia to remain living at home, means that there will be a growing demand for dementia care in the community setting. However, GPs are challenged by dementia care and have identified it as an area in which further training is needed. Previous studies of GPs dementia care educational needs have explored the views of GPs alone, without taking the perspectives of people with dementia and family carers into account. The aim of the study was to explore GPs' dementia care educational needs, as viewed from multiple perspectives, in order to inform the design and delivery of an educational programme for GPs. A qualitative study of GPs, people with dementia and family carers in a community setting was undertaken. Face-to-face interviews were performed with GPs, people with dementia and with family carers. Interviews were audio-recorded, transcribed verbatim and thematically analysed. Thirty-one people were interviewed, consisting of fourteen GPs, twelve family carers and five people with dementia. GPs expressed a wish for further education, preferentially through small group workshops. Five distinct educational needs emerged from the interviews, namely, diagnosis, disclosure, signposting of local services, counselling and the management of behavioural and psychological symptoms (BPSD). While GPs focused on diagnosis, disclosure and BPSD in particular, people with dementia and family carers emphasised the need for GPs to engage in counselling and signposting of local services. The triangulation of data from multiple relevant sources revealed a broader range of GPs' educational needs, incorporating both medical and social aspects of dementia care. The findings of this study will inform the content and delivery of a dementia educational programme for GPs that is practice-relevant, by ensuring that the curriculum meets the needs of GPs, patients and their families.

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.

The Evolution of Global Positioning System (GPS) Technology.

Science.gov (United States)

Kumar, Sameer; Moore, Kevin B.

2002-01-01

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

Inversion of GPS meteorology data

Directory of Open Access Journals (Sweden)

K. Hocke

Full Text Available The GPS meteorology (GPS/MET experiment, led by the Universities Corporation for Atmospheric Research (UCAR, consists of a GPS receiver aboard a low earth orbit (LEO satellite which was launched on 3 April 1995. During a radio occultation the LEO satellite rises or sets relative to one of the 24 GPS satellites at the Earth's horizon. Thereby the atmospheric layers are successively sounded by radio waves which propagate from the GPS satellite to the LEO satellite. From the observed phase path increases, which are due to refraction of the radio waves by the ionosphere and the neutral atmosphere, the atmospheric parameter refractivity, density, pressure and temperature are calculated with high accuracy and resolution (0.5–1.5 km. In the present study, practical aspects of the GPS/MET data analysis are discussed. The retrieval is based on the Abelian integral inversion of the atmospheric bending angle profile into the refractivity index profile. The problem of the upper boundary condition of the Abelian integral is described by examples. The statistical optimization approach which is applied to the data above 40 km and the use of topside bending angle profiles from model atmospheres stabilize the inversion. The retrieved temperature profiles are compared with corresponding profiles which have already been calculated by scientists of UCAR and Jet Propulsion Laboratory (JPL, using Abelian integral inversion too. The comparison shows that in some cases large differences occur (5 K and more. This is probably due to different treatment of the upper boundary condition, data runaways and noise. Several temperature profiles with wavelike structures at tropospheric and stratospheric heights are shown. While the periodic structures at upper stratospheric heights could be caused by residual errors of the ionospheric correction method, the periodic temperature fluctuations at heights below 30 km are most likely caused by atmospheric waves (vertically

The lesson learnt during interact - I and INTERACT - II actris measurement campaigns

Directory of Open Access Journals (Sweden)

Rosoldi Marco

2018-01-01

Full Text Available The INTERACT-II (INTERcomparison of Aerosol and Cloud Tracking campaign, performed at the CNR-IMAA Atmospheric Observatory (760 m a.s.l., 40.60° N, 15.72° E, aims to evaluate the performances of commercial automatic lidars and ceilometers for atmospheric aerosol profiling, through the comparison with Potenza EARLINET (European Aerosol Research Lidar NETwork lidars. The results of the campaign and the overall lesson learnt within INTERACT-I and INTERACT-II ACTRIS campaigns will be presented.

GPS queues with heterogeneous traffic classes

NARCIS (Netherlands)

Borst, Sem; Mandjes, M.R.H.; van Uitert, Miranda

2002-01-01

We consider a queue fed by a mixture of light-tailed and heavy-tailed traffic. The two traffic classes are served in accordance with the generalized processor sharing (GPS) discipline. GPS-based scheduling algorithms, such as weighted fair queueing (WFQ), have emerged as an important mechanism for

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

Safety campaigns. TIS Launches New Safety Information Campaign

CERN Multimedia

2001-01-01

Need to start a new installation and worried about safety aspects? Or are you newly responsible for safety matters in a CERN building? Perhaps you're simply interested in how to make the working environment safer for yourself and your colleagues. Whatever the case, a new information campaign launched by TIS this week can help. The most visible aspects of the new campaign will be posters distributed around the Laboratory treating a different subject each month. The Web site - http://safety.cern.ch/ - which provides all safety related information. But these are not the only aspects of the new campaign. Members of the TIS/GS group, whose contact details can be found on the safety web site, are available to give information and advice on a one-to-one basis at any time. The campaign's launch has been timed to coincide with European Safety Week, organized by the European Agency for Safety and Health at Work and the subject treated in the first posters is safety inspection. This particular topic only concerns thos...

Application of GPS systems on a mobile robot

Science.gov (United States)

Cao, Peter; Saxena, Mayank; Tedder, Maurice; Mischalske, Steve; Hall, Ernest L.

2001-10-01

The purpose of this paper is to describe the use of Global Positioning Systems (GPS) as geographic information and navigational system for a ground based mobile robot. Several low cost wireless systems are now available for a variety of innovative automobile applications including location, messaging and tracking and security. Experiments were conducted with a test bed mobile robot, Bearcat II, for point-to-point motion using a Motorola GPS in June 2001. The Motorola M12 Oncore GPS system is connected to the Bearcat II main control computer through a RS232 interface. A mapping program is used to define a desired route. Then GPS information may be displayed for verification. However, the GPS information is also used to update the control points of the mobile robot using a reinforcement learning method. Local position updates are also used when found in the environment. The significance of the method is in extending the use of GPS to local vehicle control that requires more resolution that is available from the raw data using the adaptive control method.

Design and testing of a GPS/GSM collar prototype to combat cattle rustling

Directory of Open Access Journals (Sweden)

Francesco M. Tangorra

2013-10-01

Full Text Available Rustling is an age-old practice that was widespread in Italy until the first half of the 20th century. Today, incidents of cattle rustling are again being reported. However, the problem is not only found in Italy. It is also becoming a plague for ranchers in the US and is still rampant in East Africa. In Italy, the cattle rustling phenomena have usually been limited through the direct control of the herdsmen. Global positioning system (GPS and geographic information system (GIS combined technologies are increasingly applied for tracking and monitoring livestock with greater spatial and temporal resolution. However, so far, no case studies of the use of GPS technology to combat cattle rustling have been reported in the literature. The aim of this research was to develop a GPS/GSM (global system for mobile communication collar, using commercial hardware and implementing a specific software [ARVAshepherd 1.0; ARVAtec Srl, Rescaldina (MI, Italy] to track animals’ movements outside their grazing area and to signal when animals are straying outside virtual perimeters. A phase I study was conducted from January to June 2011 to build the GPS/GSM collar and to assess its performances in terms of GPS accuracy and precision, while a phase II study was conducted in July 2011 to test the GPS collar under real-life operating conditions. The static GPS positioning error achieved a circular error probable (50% and horizontal 95% accuracy of 1.462 m and 4.501 m, respectively. This is comparable with values obtained by other authors in static tests of a commercial GPS collar for grazing studies. In field tests, the system was able to identify the incorrect position of the cattle and the warning messages were sent promptly to the farmer, continuing until the animals had been repositioned inside the fence, thus highlighting the potential of the GPS/GSM collar as an anti-theft system.

PERBANDINGAN IMPLEMENTASI ADVERTISING CAMPAIGN

OpenAIRE

Francisca Hanna , Febrianti

2013-01-01

Advertising campaign merupakan serangkaian bentuk iklan melalui berbagai media dan berpusat pada satu tema dalam satu waktu. Tujuan utama advertising campaign adalah menyampaikan pesan dalam suatu tema yang diluncurkan kepada masyarakat sehingga tema tersebut menjadi ciri khas produk. Peluncuran tema campaign oleh Coca Cola dan Pepsi yang merupakan rival dalam kategori beverage merupakan obyek dari penelitian ini. Kesuksesan sebuah tema advertising campaign dilihat dengan menggunakan paramet...

GPS-Aided Video Tracking

Directory of Open Access Journals (Sweden)

Udo Feuerhake

2015-08-01

Full Text Available Tracking moving objects is both challenging and important for a large variety of applications. Different technologies based on the global positioning system (GPS and video or radio data are used to obtain the trajectories of the observed objects. However, in some use cases, they fail to provide sufficiently accurate, complete and correct data at the same time. In this work we present an approach for fusing GPS- and video-based tracking in order to exploit their individual advantages. In this way we aim to combine the reliability of GPS tracking with the high geometric accuracy of camera detection. For the fusion of the movement data provided by the different devices we use a hidden Markov model (HMM formulation and the Viterbi algorithm to extract the most probable trajectories. In three experiments, we show that our approach is able to deal with challenging situations like occlusions or objects which are temporarily outside the monitored area. The results show the desired increase in terms of accuracy, completeness and correctness.

A Low Cost GPS System for Real-Time Tracking of Sounding Rockets

Science.gov (United States)

Markgraf, M.; Montenbruck, O.; Hassenpflug, F.; Turner, P.; Bull, B.; Bauer, Frank (Technical Monitor)

2001-01-01

This paper describes the development as well as the on-ground and the in-flight evaluation of a low cost Global Positioning System (GPS) system for real-time tracking of sounding rockets. The flight unit comprises a modified ORION GPS receiver and a newly designed switchable antenna system composed of a helical antenna in the rocket tip and a dual-blade antenna combination attached to the body of the service module. Aside from the flight hardware a PC based terminal program has been developed to monitor the GPS data and graphically displays the rocket's path during the flight. In addition an Instantaneous Impact Point (IIP) prediction is performed based on the received position and velocity information. In preparation for ESA's Maxus-4 mission, a sounding rocket test flight was carried out at Esrange, Kiruna, on 19 Feb. 2001 to validate existing ground facilities and range safety installations. Due to the absence of a dedicated scientific payload, the flight offered the opportunity to test multiple GPS receivers and assess their performance for the tracking of sounding rockets. In addition to the ORION receiver, an Ashtech G12 HDMA receiver and a BAE (Canadian Marconi) Allstar receiver, both connected to a wrap-around antenna, have been flown on the same rocket as part of an independent experiment provided by the Goddard Space Flight Center. This allows an in-depth verification and trade-off of different receiver and antenna concepts.

High-sensitivity modified Glasgow prognostic score (HS-mGPS) Is superior to the mGPS in esophageal cancer patients treated with chemoradiotherapy

OpenAIRE

Chen, Peng; Fang, Min; Wan, Qiuyan; Zhang, Xuebang; Song, Tao; Wu, Shixiu

2017-01-01

The present study compared the prognostic value of the modified Glasgow prognostic score (mGPS) and high-sensitivity mGPS (HS-mGPS) in unresectable locally advanced esophageal squamous cell carcimona (LAESCC) patients treated with concurrent chemoradiotherapy (CCRT). The baseline data of 163 eligible patients were retrospectively collected. Patients with a C-reactive protein (CRP) ≤ 10 mg/l and albumin ≥ 35 g/l were allocated to mGPS-0 group. Patients with only elevated CRP (> 10 mg/l) were a...

Estimering af brændstofforbrug vha. GPS Data

DEFF Research Database (Denmark)

Andersen, Ove; Lahrmann, Harry; Torp, Kristian

2010-01-01

Det er simpelt og billigt at opsamle GPS målinger fra køretøjer. Når større mængder GPS data indsamles fra et passende antal køretøjer kan dataen bruges til at beregne f.eks. køretider. Det er ligeledes muligt ud fra GPS data at estimere miljøindikatorer så som, hvor aggressivt kører bilister og er...... der nogle vejstrækninger, der har en højere (negativ) miljø påvirkning end andre? I denne artikel præsenterer et forsøg, hvor GPS data anvendes til at estimere brændstofforbruget ved en enkelt tur og for vejnettet generelt. Dette gøres ved at opbygge en database med GPS data. Ud fra disse data gives...

The (n,γ campaigns at EXILL

Directory of Open Access Journals (Sweden)

Jolie J.

2015-01-01

Full Text Available At the PF1B cold neutron beam line at the Institut Laue Langevin, the EXILL array consisting of EXOGAM, GASP and ILL-Clover detectors was used to perform (n,γ measurements at very high coincidence rates. About ten different reactions were measured in autumn 2012 using a highly collimated cold neutron beam. In spring 2013, the EXOGAM array was combined with 16 LaBr3(Ce scintillators in the EXILL&FATIMA campaign for the measurement of lifetimes using the generalised centroid difference method. We report on the properties of the set-ups and present first results from both campaigns.

Campaigns Matter

DEFF Research Database (Denmark)

Hansen, Kasper Møller; Pedersen, Rasmus Tue

2014-01-01

and the external efficacy increase over the course of the campaign, with gains found across different demographic groups, particularly narrowing the gaps in internal efficacy. The news media play a crucial role, as increased knowledge and efficacy are partly driven by media use, although tabloids actually decrease...... external efficacy. The findings suggest that positive campaign effects are universal across various media and party systems.......Election campaigns are more than simple competitions for votes; they also represent an opportunity for voters to become politically knowledgeable and engaged. Using a large-scale web panel (n≈5,000), we track the development of political knowledge, internal efficacy and external efficacy among...

GPS-seismograms reveal amplified shaking in California's San Joaquin Delta region

Science.gov (United States)

Johanson, I. A.

2014-12-01

The March 10, 2014, the Mw6.8 Ferndale earthquake occurred off the coast of Northern California, near the Mendocino Triple Junction. Aftershocks suggest a northeast striking fault plane for the strike-slip earthquake, oriented such that the California coast is roughly perpendicular to the rupture plane. Consequently, large amplitude Love waves were observed at seismic stations and continuous GPS stations throughout Northern California. While GPS is less sensitive then broadband instruments, in Northern California their station density is much higher, potentially providing valuable detail. A total of 269 GPS stations that have high-rate (1 sps) data available were used to generate GPS-seismograms. These include stations from the Bay Area Regional Deformation (BARD) network, the Plate Boundary Observatory (PBO, operated by UNAVCO), and the USGS, Menlo Park. The Track software package was used to generate relative displacements between pairs of stations, determined using Delaunay triangulation. This network-based approach allows for higher precision than absolute positioning, because common noise sources, in particular atmospheric noise, are cancelled out. A simple least-squares network adjustment with a stable centroid constraint is performed to transform the mesh of relative motions into absolute motions at individual GPS stations. This approach to generating GPS-seismograms is validated by the good agreement between time series records at 16 BARD stations that are co-located with broadband seismometers from the Berkeley Digital Seismic Network (BDSN). While the distribution of peak dynamic displacements is dominated in long periods by the radiation pattern, at shorter periods other patterns become visible. In particular, stations in the San Joaquin Delta (SJD) region show higher peak dynamic displacements than those in surrounding areas, as well as longer duration shaking. SJD stations also have higher dynamic displacements on the radial component than surrounding

Overcoming urban GPS navigation challenges through the use of MEMS inertial sensors and proper verification of navigation system performance

Science.gov (United States)

Vinande, Eric T.

This research proposes several means to overcome challenges in the urban environment to ground vehicle global positioning system (GPS) receiver navigation performance through the integration of external sensor information. The effects of narrowband radio frequency interference and signal attenuation, both common in the urban environment, are examined with respect to receiver signal tracking processes. Low-cost microelectromechanical systems (MEMS) inertial sensors, suitable for the consumer market, are the focus of receiver augmentation as they provide an independent measure of motion and are independent of vehicle systems. A method for estimating the mounting angles of an inertial sensor cluster utilizing typical urban driving maneuvers is developed and is able to provide angular measurements within two degrees of truth. The integration of GPS and MEMS inertial sensors is developed utilizing a full state navigation filter. Appropriate statistical methods are developed to evaluate the urban environment navigation improvement due to the addition of MEMS inertial sensors. A receiver evaluation metric that combines accuracy, availability, and maximum error measurements is presented and evaluated over several drive tests. Following a description of proper drive test techniques, record and playback systems are evaluated as the optimal way of testing multiple receivers and/or integrated navigation systems in the urban environment as they simplify vehicle testing requirements.

Do social marketing campaigns in health work? A critical analysis of four UK campaigns

OpenAIRE

Coope, David

2007-01-01

This management project looks at four recent social marketing campaigns in the field of health in the UK to determine whether such campaigns work. The project critically analyses the marketing campaigns used, and aims to determine the range of factors that create a successful social marketing campaign in health. There is analysis of four case studies undertaken after secondary research into social marketing campaigns run by a range of different organisations. The case studies are the ...

Single-Receiver GPS Phase Bias Resolution

Science.gov (United States)

Bertiger, William I.; Haines, Bruce J.; Weiss, Jan P.; Harvey, Nathaniel E.

2010-01-01

Existing software has been modified to yield the benefits of integer fixed double-differenced GPS-phased ambiguities when processing data from a single GPS receiver with no access to any other GPS receiver data. When the double-differenced combination of phase biases can be fixed reliably, a significant improvement in solution accuracy is obtained. This innovation uses a large global set of GPS receivers (40 to 80 receivers) to solve for the GPS satellite orbits and clocks (along with any other parameters). In this process, integer ambiguities are fixed and information on the ambiguity constraints is saved. For each GPS transmitter/receiver pair, the process saves the arc start and stop times, the wide-lane average value for the arc, the standard deviation of the wide lane, and the dual-frequency phase bias after bias fixing for the arc. The second step of the process uses the orbit and clock information, the bias information from the global solution, and only data from the single receiver to resolve double-differenced phase combinations. It is called "resolved" instead of "fixed" because constraints are introduced into the problem with a finite data weight to better account for possible errors. A receiver in orbit has much shorter continuous passes of data than a receiver fixed to the Earth. The method has parameters to account for this. In particular, differences in drifting wide-lane values must be handled differently. The first step of the process is automated, using two JPL software sets, Longarc and Gipsy-Oasis. The resulting orbit/clock and bias information files are posted on anonymous ftp for use by any licensed Gipsy-Oasis user. The second step is implemented in the Gipsy-Oasis executable, gd2p.pl, which automates the entire process, including fetching the information from anonymous ftp

Study of Atmospheric Forcing and Responses (SAFAR campaign: overview

Directory of Open Access Journals (Sweden)

A. Jayaraman

2010-01-01

Full Text Available Study of Atmospheric Forcing and Responses (SAFAR is a five year (2009–2014 research programme specifically to address the responses of the earth's atmosphere to both natural and anthropogenic forcings using a host of collocated instruments operational at the National Atmospheric Research Laboratory, Gadanki (13.5° N, 79.2° E, India from a unified viewpoint of studying the vertical coupling between the forcings and responses from surface layer to the ionosphere. As a prelude to the main program a pilot campaign was conducted at Gadanki during May–November 2008 using collocated observations from the MST radar, Rayleigh lidar, GPS balloonsonde, and instruments measuring aerosol, radiation and precipitation, and supporting satellite data. We show the importance of the large radiative heating caused by absorption of solar radiation by soot particles in the lower atmosphere, the observed high vertical winds in the convective updrafts extending up to tropopause, and the difficulty in simulating the same with existing models, the upward traveling waves in the middle atmosphere coupling the lower atmosphere with the upper atmosphere, their manifestation in the mesospheric temperature structure and inversion layers, the mesopause height extending up to 100 km, and the electro-dynamical coupling between mesosphere and the ionosphere which causes irregularities in the ionospheric F-region. The purpose of this communication is not only to share the knowledge that we gained from the SAFAR pilot campaign, but also to inform the international atmospheric science community about the SAFAR program as well as to extend our invitation to join in our journey.

How and Why to Do VLBI on GPS

Science.gov (United States)

Dickey, J. M.

2010-01-01

In order to establish the position of the center of mass of the Earth in the International Celestial Reference Frame, observations of the Global Positioning Satellite (GPS) constellation using the IVS network are important. With a good frame-tie between the coordinates of the IVS telescopes and nearby GPS receivers, plus a common local oscillator reference signal, it should be possible to observe and record simultaneously signals from the astrometric calibration sources and the GPS satellites. The standard IVS solution would give the atmospheric delay and clock offsets to use in analysis of the GPS data. Correlation of the GPS signals would then give accurate orbital parameters of the satellites in the ICRF reference frame, i.e., relative to the positions of the astrometric sources. This is particularly needed to determine motion of the center of mass of the earth along the rotation axis.

Localization system for use in GPS denied environments

Energy Technology Data Exchange (ETDEWEB)

Trueblood, J. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2017-02-01

The military uses to autonomous platforms to complete missions to provide standoff for the warfighters. However autonomous platforms rely on GPS to provide their global position. In many missions spaces the autonomous platforms may encounter GPS denied environments which limits where the platform operates and requires the warfighters to takes its place. GPS denied environments can occur due to tall building, trees, canyon wall blocking the GPS satellite signals or a lack of coverage. An Inertial Navigation System (INS) uses sensors to detect the vehicle movement and direction its traveling to calculate the vehicle. One of biggest challenges with an INS system is the accuracy and accumulation of errors over time of the sensors. If these challenges can be overcome the INS would provide accurate positioning information to the autonomous vehicle in GPS denied environments and allow them to provide the desired standoff for the warfighters.

Development of GPS Receiver Kalman Filter Algorithms for Stationary, Low-Dynamics, and High-Dynamics Applications

Science.gov (United States)

2016-06-01

Filter Algorithms for Stationary, Low-Dynamics, and High-Dynamics Applications Executive Summary The Global Positioning system ( GPS ) is the primary...software that may need to be developed for performance prediction of current or future systems that incorporate GPS . The ultimate aim is to help inform...Defence Science and Technology Organisation in 1986. His major areas of work were adaptive tracking , sig- nal processing, and radar systems engineering

GPS antenna designs

Science.gov (United States)

Laube, Samuel J. P.

1987-05-01

Application of the current GPS NAVSTAR system to civilian service requires that a right hand, circularly polarized, -160 dBW spread spectrum signal be received from an orbiting satellite, where the antenna environment is also moving. This presents a design challenge when inexpensive antennas are desired. The intent of this survey is to provide information on the antennas mentioned and to construct and test prototypes to determine whether the choice made by the industry, the quadrifilar helix, is the best. The helix antenna is currently the low cost standard for GPS. Prototype versions were constructed using 12 gauge wire and subminiature coaxial hardline. The constructed antennas were tested using a signal generator and a reference turnstile. A spectrum analyzer was used to measure the level of the received signal.

Road Traffic Anomaly Detection via Collaborative Path Inference from GPS Snippets

Directory of Open Access Journals (Sweden)

Hongtao Wang

2017-03-01

Full Text Available Road traffic anomaly denotes a road segment that is anomalous in terms of traffic flow of vehicles. Detecting road traffic anomalies from GPS (Global Position System snippets data is becoming critical in urban computing since they often suggest underlying events. However, the noisy ands parse nature of GPS snippets data have ushered multiple problems, which have prompted the detection of road traffic anomalies to be very challenging. To address these issues, we propose a two-stage solution which consists of two components: a Collaborative Path Inference (CPI model and a Road Anomaly Test (RAT model. CPI model performs path inference incorporating both static and dynamic features into a Conditional Random Field (CRF. Dynamic context features are learned collaboratively from large GPS snippets via a tensor decomposition technique. Then RAT calculates the anomalous degree for each road segment from the inferred fine-grained trajectories in given time intervals. We evaluated our method using a large scale real world dataset, which includes one-month GPS location data from more than eight thousand taxi cabs in Beijing. The evaluation results show the advantages of our method beyond other baseline techniques.

Improved GPS-based Satellite Relative Navigation Using Femtosecond Laser Relative Distance Measurements

Directory of Open Access Journals (Sweden)

Hyungjik Oh

2016-03-01

Full Text Available This study developed an approach for improving Carrier-phase Differential Global Positioning System (CDGPS based realtime satellite relative navigation by applying laser baseline measurement data. The robustness against the space operational environment was considered, and a Synthetic Wavelength Interferometer (SWI algorithm based on a femtosecond laser measurement model was developed. The phase differences between two laser wavelengths were combined to measure precise distance. Generated laser data were used to improve estimation accuracy for the float ambiguity of CDGPS data. Relative navigation simulations in real-time were performed using the extended Kalman filter algorithm. The GPS and laser-combined relative navigation accuracy was compared with GPS-only relative navigation solutions to determine the impact of laser data on relative navigation. In numerical simulations, the success rate of integer ambiguity resolution increased when laser data was added to GPS data. The relative navigational errors also improved five-fold and two-fold, relative to the GPS-only error, for 250 m and 5 km initial relative distances, respectively. The methodology developed in this study is suitable for application to future satellite formation-flying missions.

The use of the AOA TTR-4P GPS receiver in operation at the BIPM for real-time restitution of GPS time

Science.gov (United States)

Thomas, Claudine

1994-01-01

The Global Positioning System is an outstanding tool for the dissemination of time. Using mono-channel C/A-code GPS time receivers, the restitution of GPS time through the satellite constellation presents a peak-to-peak discrepancy of several tens of nanoseconds without SA but may be as high as several hundreds of nanoseconds with SA. As a consequence, civil users are more and more interested in implementing hardware and software methods for efficient restitution of GPS time, especially in the framework of the project of a real-time prediction of UTC (UTCp) which could be available in the form of time differences (UTCp - GPS time). Previous work, for improving the real-time restitution of GPS time with SA, to the level obtained without SA, focused on the implementation of a Kalman filter based on past data and updated at each new observation. An alternative solution relies upon the statistical features of the noise brought about by SA; it has already been shown that the SA noise is efficiently reduced by averaging data from numerous satellites observed simultaneously over a sufficiently long time. This method was successfully applied to data from a GPS time receiver, model AOA TTR-4P, connected to the cesium clock kept at the BIPM. This device, a multi-channel, dual frequency, P-code GPS time receiver, is one of the first TTR-4P units in operation in a civil laboratory. Preliminary comparative studies of this new equipment with conventional GPS time receivers are described in this paper. The results of an experimental restitution of GPS time, obtained in June 1993, are also detailed: 3 to 6 satellites were observed simultaneously with a sample interval of 15 s, an efficient smoothing of SA noise was realized by averaging data on all observed satellites over more than 1 hour. When the GPS system is complete in 1994, 8 satellites will be observable continuously from anywhere in the world and the same level of uncertainty will be obtained using a shorter averaging

Uporaba satelitskih sistemov GPS in GLONASS v geodetski izmeri

OpenAIRE

Oset, Klemen

2015-01-01

V geodetski izmeri GNSS se že nekaj časa za določanje položaja uporabljata hkrati sistema GLONASS in GPS. V diplomski nalogi sta predstavljena GNSS sistema GPS in GLONASS, podobnosti in razlike obeh sistemov ter njune značilnosti pri določitvi položaja. V praktičnem delu naloge so predstavljeni potek meritev, obdelava opazovanj in analiza kakovosti koordinat določenih na osnovi opazovanj GPS, opazovanj GLONASS in skupne uporabe opazovanj GPS in GLONASS.

Mining Significant Semantic Locations from GPS Data

DEFF Research Database (Denmark)

Cao, Xin; Cong, Gao; Jensen, Christian Søndergaard

2010-01-01

With the increasing deployment and use of GPS-enabled devices, massive amounts of GPS data are becoming available. We propose a general framework for the mining of semantically meaningful, significant locations, e.g., shopping malls and restaurants, from such data. We present techniques capable...... of extracting semantic locations from GPS data. We capture the relationships between locations and between locations and users with a graph. Significance is then assigned to locations using random walks over the graph that propagates significance among the locations. In doing so, mutual reinforcement between...

Mining significant semantic locations from GPS data

DEFF Research Database (Denmark)

Cao, Xin; Cong, Gao; Jensen, Christian S.

2010-01-01

With the increasing deployment and use of GPS-enabled devices, massive amounts of GPS data are becoming available. We propose a general framework for the mining of semantically meaningful, significant locations, e.g., shopping malls and restaurants, from such data. We present techniques capable...... of extracting semantic locations from GPS data. We capture the relationships between locations and between locations and users with a graph. Significance is then assigned to locations using random walks over the graph that propagates significance among the locations. In doing so, mutual reinforcement between...

Corporate campaign contributions and abnormal stock returns after presidential elections

OpenAIRE

Juergen Huber; Michael Kirchler

2008-01-01

In the U.S. campaign contributions by companies play a major role in financing election campaigns. We analyze contributions by companies before an election and stock market performance after the election for the presidential elections from 1992 until 2004. We find that (i) the percentage of contributions given to the winner in a presidential election and (ii) the total contribution (divided by market capitalization) have a significant positive impact on a company's stock market performance af...

Precise Orbit Determination of GPS Satellites Using Phase Observables

Directory of Open Access Journals (Sweden)

Myung-Kook Jee

1997-12-01

Full Text Available The accuracy of user position by GPS is heavily dependent upon the accuracy of satellite position which is usually transmitted to GPS users in radio signals. The real-time satellite position information directly obtained from broadcast ephimerides has the accuracy of 3 x 10 meters which is very unsatisfactory to measure 100km baseline to the accuracy of less than a few mili-meters. There are globally at present seven orbit analysis centers capable of generating precise GPS ephimerides and their orbit quality is of the order of about 10cm. Therefore, precise orbit model and phase processing technique were reviewed and consequently precise GPS ephimerides were produced after processing the phase observables of 28 global GPS stations for 1 day. Initial 6 orbit parameters and 2 solar radiation coefficients were estimated using batch least square algorithm and the final results were compared with the orbit of IGS, the International GPS Service for Geodynamics.

Enhancing the accuracy of GPS point positioning by converting the single frequency data to dual frequency data

Directory of Open Access Journals (Sweden)

Aly M. El-naggar

2011-09-01

Full Text Available The global positioning system (GPS has been used to support a wide variety of applications, such as high-accuracy positioning and navigation. Differential GPS techniques can largely eliminate common-mode errors between the reference and the rover GPS stations resulting from ionospheric and tropospheric refraction and delays, satellite and receiver clock biases, and orbital errors [1]. The ionospheric delay in the propagation of global positioning system (GPS signals is one of the main sources of error in GPS precise positioning and navigation. A dual-frequency GPS receiver can eliminate (to the first order the ionospheric delay through a linear combination of the L1 and L2 observations [2]. The most significant effect of ionospheric delay appear in case of using single frequency data. In this paper the single frequency data of concerned station are converted to dual frequency data by employing dual frequency data from 11 regional GPS stations distributed around it. Total electron content (TEC was calculated at every GPS station to produce the mathematical model of TEC which is a function of latitude (Φ and longitude (λ. By using this mathematical model the values of TEC and L2 can be predicted at the single frequency GPS station for each satellite, after that the comparison between predicted and observation values of TEC and L2 was performed. The estimation method and test results of the proposed method indicates that the difference between predicted and observation values is very small.

Volcanic Surface Deformation in Dominica From GPS Geodesy: Results From the 2007 NSF- REU Site

Science.gov (United States)

Murphy, R.; James, S.; Styron, R. H.; Turner, H. L.; Ashlock, A.; Cavness, C.; Collier, X.; Fauria, K.; Feinstein, R.; Staisch, L.; Williams, B.; Mattioli, G. S.; Jansma, P. E.; Cothren, J.

2007-12-01

GPS measurements have been collected on the island of Dominica in the Lesser Antilles between 2001 and 2007, with five month-long campaigns completed in June of each year supported in part by a NSF REU Site award for the past two years. All GPS data were collected using dual-frequency, code-phase receivers and geodetic-quality antenna, primarily choke rings. Three consecutive 24 hr observation days were normally obtained for each site. Precise station positions were estimated with GIPSY-OASISII using an absolute point positioning strategy and final, precise orbits, clocks, earth orientation parameters, and x-files. All position estimates were updated to ITRF05 and a revised Caribbean Euler pole was used to place our observations in a CAR-fixed frame. Time series were created to determine the velocity of each station. Forward and inverse elastic half-space models with planar (i.e. dike) and Mogi (i.e. point) sources were investigated. Inverse modeling was completed using a downhill simplex method of function minimization. Selected site velocities were used to create appropriate models for specific regions of Dominica, which correspond to known centers of pre-historic volcanic or recent shallow, seismic activity. Because of the current distribution of GPS sites with robust velocity estimates, we limit our models to possible magmatic activity in the northern, proximal to the volcanic centers of Morne Diablotins and Morne aux Diables, and southern, proximal to volcanic centers of Soufriere and Morne Plat Pays, regions of the island. Surface deformation data from the northernmost sites may be fit with the development of a several km-long dike trending approximately northeast- southwest. Activity in the southern volcanic centers is best modeled by an expanding point source at approximately 1 km depth.

Analysis of signal acquisition in GPS receiver software

Directory of Open Access Journals (Sweden)

Vlada S. Sokolović

2011-01-01

Full Text Available This paper presents a critical analysis of the flow signal processing carried out in GPS receiver software, which served as a basis for a critical comparison of different signal processing architectures within the GPS receiver. It is possible to achieve Increased flexibility and reduction of GPS device commercial costs, including those of mobile devices, by using radio technology software (SDR, Software Defined Radio. The SDR application can be realized when certain hardware components in a GPS receiver are replaced. Signal processing in the SDR is implemented using a programmable DSP (Digital Signal Processing or FPGA (Field Programmable Gate Array circuit, which allows a simple change of digital signal processing algorithms and a simple change of the receiver parameters. The starting point of the research is the signal generated on the satellite the structure of which is shown in the paper. Based on the GPS signal structure, a receiver is realized with a task to extract an appropriate signal from the spectrum and detect it. Based on collected navigation data, the receiver calculates the position of the end user. The signal coming from the satellite may be at the carrier frequencies of L1 and L2. Since the SPS is used in the civil service, all the tests shown in the work were performed on the L1 signal. The signal coming to the receiver is generated in the spread spectrum technology and is situated below the level of noise. Such signals often interfere with signals from the environment which presents a difficulty for a receiver to perform proper detection and signal processing. Therefore, signal processing technology is continually being improved, aiming at more accurate and faster signal processing. All tests were carried out on a signal acquired from the satellite using the SE4110 input circuit used for filtering, amplification and signal selection. The samples of the received signal were forwarded to a computer for data post processing, i. e

Performance Analysis of Measurement Inaccuracies of IMU/GPS on Airborne Repeat-pass Interferometric SAR in the Presence of Squint

Directory of Open Access Journals (Sweden)

Deng Yuan

2014-08-01

Full Text Available In the MOtion COmpensation (MOCO approach to airborne repeat-pass interferometric Synthetic Aperture Radar (SAR based on motion measurement data, the measurement inaccuracies of Inertial Measurement Unit/Global Positioning System (IMU/GPS and the positioning errors of the target, which may contribute to the residual uncompensated motion errors, affect the imaging result and interferometric measurement. Considering the effects of the two types of error, this paper builds a mathematical model of residual motion errors in presence of squint, and analyzes the effects on the residual motion errors induced by the measurement inaccuracies of IMU/GPS and the positioning errors of the target. In particular, the effects of various measurement inaccuracies of IMU/GPS on interferometric SAR image quality, interferometric phase, and digital elevation model precision are disscussed. Moreover, the paper quantitatively researches the effects of residual motion errors on airborne repeat-pass interferometric SAR through theoretical and simulated analyses and provides theoretical bases for system design and signal processing.

BDS/GPS Dual Systems Positioning Based on the Modified SR-UKF Algorithm

Directory of Open Access Journals (Sweden)

JaeHyok Kong

2016-05-01

Full Text Available The Global Navigation Satellite System can provide all-day three-dimensional position and speed information. Currently, only using the single navigation system cannot satisfy the requirements of the system’s reliability and integrity. In order to improve the reliability and stability of the satellite navigation system, the positioning method by BDS and GPS navigation system is presented, the measurement model and the state model are described. Furthermore, the modified square-root Unscented Kalman Filter (SR-UKF algorithm is employed in BDS and GPS conditions, and analysis of single system/multi-system positioning has been carried out, respectively. The experimental results are compared with the traditional estimation results, which show that the proposed method can perform highly-precise positioning. Especially when the number of satellites is not adequate enough, the proposed method combine BDS and GPS systems to achieve a higher positioning precision.

PDOP values for simulated GPS/Galileo positioning

DEFF Research Database (Denmark)

Cederholm, Jens Peter

2005-01-01

The paper illustrates satellite coverage and PDOP values for a simulated combined GPS/Galileo system. The designed GPS satellite constellation and the planned Galileo satellite constellation are presented. The combined system is simulated and the number of visible satellites and PDOP values...

Inversion of GPS-measured coseismic displacements for source parameters of Taiwan earthquake

Science.gov (United States)

Lin, J. T.; Chang, W. L.; Hung, H. K.; Yu, W. C.

2016-12-01

We performed a method of determining earthquake location, focal mechanism, and centroid moment tensor by coseismic surface displacements from daily and high-rate GPS measurements. Unlike commonly used dislocation model where fault geometry is calculated nonlinearly, our method makes a point source approach to evaluate these parameters in a solid and efficient way without a priori fault information and can thus provide constrains to subsequent finite source modeling of fault slip. In this study, we focus on the resolving ability of GPS data for moderate (Mw=6.0 7.0) earthquakes in Taiwan, and four earthquakes were investigated in detail: the March 27 2013 Nantou (Mw=6.0), the June 2 2013 Nantou (Mw=6.3) , the October 31 2013 Ruisui (Mw=6.3), and the March 31 2002 Hualien (ML=6.8) earthquakes. All these events were recorded by the Taiwan continuous GPS network with data sampling rates of 30-second and 1 Hz, where the Mw6.3 Ruisui earthquake was additionally recorded by another local GPS network with a sampling rate of 20 Hz. Our inverted focal mechanisms of all these earthquakes are consistent with the results of GCMT and USGS that evaluates source parameters by dynamic information from seismic waves. We also successfully resolved source parameters of the Mw6.3 Ruisui earthquake within only 10 seconds following the earthquake occurrence, demonstrating the potential of high-rate GPS data on earthquake early warning and real-time determination of earthquake source parameters.

A New Trajectory Similarity Measure for GPS Data

KAUST Repository

Ismail, Anas; Vigneron, Antoine E.

2016-01-01

We present a new algorithm for measuring the similarity between trajectories, and in particular between GPS traces. We call this new similarity measure the Merge Distance (MD). Our approach is robust against subsampling and supersampling. We perform experiments to compare this new similarity measure with the two main approaches that have been used so far: Dynamic Time Warping (DTW) and the Euclidean distance. © 2015 ACM.

A New Trajectory Similarity Measure for GPS Data

KAUST Repository

Ismail, Anas

2016-08-08

We present a new algorithm for measuring the similarity between trajectories, and in particular between GPS traces. We call this new similarity measure the Merge Distance (MD). Our approach is robust against subsampling and supersampling. We perform experiments to compare this new similarity measure with the two main approaches that have been used so far: Dynamic Time Warping (DTW) and the Euclidean distance. © 2015 ACM.

Combining GPS measurements and IRI model predictions

International Nuclear Information System (INIS)

Hernandez-Pajares, M.; Juan, J.M.; Sanz, J.; Bilitza, D.

2002-01-01

The free electrons distributed in the ionosphere (between one hundred and thousands of km in height) produce a frequency-dependent effect on Global Positioning System (GPS) signals: a delay in the pseudo-orange and an advance in the carrier phase. These effects are proportional to the columnar electron density between the satellite and receiver, i.e. the integrated electron density along the ray path. Global ionospheric TEC (total electron content) maps can be obtained with GPS data from a network of ground IGS (international GPS service) reference stations with an accuracy of few TEC units. The comparison with the TOPEX TEC, mainly measured over the oceans far from the IGS stations, shows a mean bias and standard deviation of about 2 and 5 TECUs respectively. The discrepancies between the STEC predictions and the observed values show an RMS typically below 5 TECUs (which also includes the alignment code noise). he existence of a growing database 2-hourly global TEC maps and with resolution of 5x2.5 degrees in longitude and latitude can be used to improve the IRI prediction capability of the TEC. When the IRI predictions and the GPS estimations are compared for a three month period around the Solar Maximum, they are in good agreement for middle latitudes. An over-determination of IRI TEC has been found at the extreme latitudes, the IRI predictions being, typically two times higher than the GPS estimations. Finally, local fits of the IRI model can be done by tuning the SSN from STEC GPS observations

Self reported involvement in emergency medicine among GPs in Norway.

Science.gov (United States)

Hjortdahl, Magnus; Zakariassen, Erik; Halvorsen, Peder A

2018-04-10

To examine general practitioners' (GPs') perception of their role in emergency medicine and participation in emergency services including ambulance call outs, and the characteristics of the GPs and casualty clinics associated with the GPs' involvement in emergency medicine. Cross-sectional online survey. General practice. General practitioners in Norway (n = 1002). Proportion of GPs perceiving that they have a large role in emergency medicine, regularly being on call, and the proportion of ambulance callouts with GP participation. Forty six percent of the GPs indicated that they play a large role in emergency medicine, 63 percent of the GPs were regularly on call, and 28 percent responded that they usually took part in ambulance call outs. Multivariable logistic regression analyses indicated that these outcomes were strongly associated with participation in multidisciplinary training. Furthermore, the main outcomes were associated with traits commonly seen at smaller casualty clinics such as those with an absence of nursing personnel and extra physicians, and based on the distance to the hospital. Our findings suggest that GPs play an important role in emergency medicine. Multidisciplinary team training may be important for their continued involvement in prehospital emergencies. Key Points   Health authorities and other stakeholders have raised concerns about general practitioner's (GPs) participation in emergency medicine, but few have studied opinions and perceptions among the GPs themselves.   • Norwegian GPs report playing a large role in emergency medicine, regularly being on call, and taking part in selected ambulance call outs.   • A higher proportion of GPs who took part in team training perceived themselves as playing a large role in emergency medicine, regularly being on call, and taking part in ambulance call outs.   • These outcomes were also associated with attributes commonly seen at smaller casualty clinics.

Near real-time GPS applications for tsunami early warning systems

Directory of Open Access Journals (Sweden)

C. Falck

2010-02-01

Full Text Available GPS (Global Positioning System technology is widely used for positioning applications. Many of them have high requirements with respect to precision, reliability or fast product delivery, but usually not all at the same time as it is the case for early warning applications. The tasks for the GPS-based components within the GITEWS project (German Indonesian Tsunami Early Warning System, Rudloff et al., 2009 are to support the determination of sea levels (measured onshore and offshore and to detect co-seismic land mass displacements with the lowest possible latency (design goal: first reliable results after 5 min. The completed system was designed to fulfil these tasks in near real-time, rather than for scientific research requirements. The obtained data products (movements of GPS antennas are supporting the warning process in different ways. The measurements from GPS instruments on buoys allow the earliest possible detection or confirmation of tsunami waves on the ocean. Onshore GPS measurements are made collocated with tide gauges or seismological stations and give information about co-seismic land mass movements as recorded, e.g., during the great Sumatra-Andaman earthquake of 2004 (Subarya et al., 2006. This information is important to separate tsunami-caused sea height movements from apparent sea height changes at tide gauge locations (sensor station movement and also as additional information about earthquakes' mechanisms, as this is an essential information to predict a tsunami (Sobolev et al., 2007.

This article gives an end-to-end overview of the GITEWS GPS-component system, from the GPS sensors (GPS receiver with GPS antenna and auxiliary systems, either onshore or offshore to the early warning centre displays. We describe how the GPS sensors have been installed, how they are operated and the methods used to collect, transfer and process the GPS data in near real-time. This includes the sensor system design, the communication

Contextual Influences and Campaign Awareness Among Young Adults: Evidence from the National truth® Campaign.

Science.gov (United States)

Vallone, Donna M; Ilakkuvan, Vinu; Xiao, Haijun; Cantrell, Jennifer; Rath, Jessica; Hair, Elizabeth

2015-01-01

Mass media campaigns have been found to shape the public's knowledge, attitudes, beliefs, and behavior around tobacco. This study examines the influence of contextual factors with respect to awareness of the national truth® campaign, a mass media, branded tobacco use prevention campaign, among a sample of young adults (n = 2,804) aged 24-34 years old; these respondents were within the age range for both the primary and secondary targets of the campaign during the period (2000-2007) when the campaign was airing television advertising at consistently high levels. Mulitvariable models reveal lower educational attainment and Hispanic ethnicity as significant contextual factors predictive of lower campaign awareness, controlling for media use. In contrast, gender, state tobacco control policy, sensation-seeking, current smoking status, and community-level SES variables were not significantly associated with campaign awareness. Further research is needed to identify the mechanisms through which public education campaigns operate, particularly among disadvantaged communities.

Convective towers detection using GPS radio occultations

DEFF Research Database (Denmark)

Biondi, Riccardo; Neubert, Torsten; Syndergaard, S.

the GPS signals penetrate through clouds and allow measurements of atmospheric profiles related to temperature, pressure, and water vapour with high vertical resolution. Using tropical cyclone best track database and data from different GPS RO missions (COSMIC, GRACE, CHAMP, SACC and GPSMET), we selected...

77 FR 23668 - GPS Satellite Simulator Working Group Notice of Meeting

Science.gov (United States)

2012-04-20

... DEPARTMENT OF DEFENSE Department of the Air Force GPS Satellite Simulator Working Group Notice of... inform the public that the Global Positioning Systems (GPS) Directorate will be hosting an open GPS Satellite Simulator Working Group (SSWG) meeting for manufacturers of GPS constellation simulators utilized...

Precise Positioning of Uavs - Dealing with Challenging Rtk-Gps Measurement Conditions during Automated Uav Flights

Science.gov (United States)

Zimmermann, F.; Eling, C.; Klingbeil, L.; Kuhlmann, H.

2017-08-01

For some years now, UAVs (unmanned aerial vehicles) are commonly used for different mobile mapping applications, such as in the fields of surveying, mining or archeology. To improve the efficiency of these applications an automation of the flight as well as the processing of the collected data is currently aimed at. One precondition for an automated mapping with UAVs is that the georeferencing is performed directly with cm-accuracies or better. Usually, a cm-accurate direct positioning of UAVs is based on an onboard multi-sensor system, which consists of an RTK-capable (real-time kinematic) GPS (global positioning system) receiver and additional sensors (e.g. inertial sensors). In this case, the absolute positioning accuracy essentially depends on the local GPS measurement conditions. Especially during mobile mapping applications in urban areas, these conditions can be very challenging, due to a satellite shadowing, non-line-of sight receptions, signal diffraction or multipath effects. In this paper, two straightforward and easy to implement strategies will be described and analyzed, which improve the direct positioning accuracies for UAV-based mapping and surveying applications under challenging GPS measurement conditions. Based on a 3D model of the surrounding buildings and vegetation in the area of interest, a GPS geometry map is determined, which can be integrated in the flight planning process, to avoid GPS challenging environments as far as possible. If these challenging environments cannot be avoided, the GPS positioning solution is improved by using obstruction adaptive elevation masks, to mitigate systematic GPS errors in the RTK-GPS positioning. Simulations and results of field tests demonstrate the profit of both strategies.

The Effect of Campaign-Generated Interpersonal Communication on Campaign-Targeted Health Outcomes: A Meta-Analysis.

Science.gov (United States)

Jeong, Michelle; Bae, Rosie Eungyuhl

2017-06-16

This study examined the effect of mass media campaign-generated conversations on campaign-targeted health outcomes, via a systematic meta-analysis of 28 studies (including 124 sub-studies and a total of 138,898 participants). The study also conducted a series of moderation analyses to examine the conditions under which interpersonal communication has larger effects on bringing about the desired outcomes. The findings of this meta-analysis indicate that campaign-generated conversations have a positive effect on inducing campaign-targeted outcomes (OR = 1.28) and show that this effect is moderated by health topic addressed by the campaign, the type of outcome being targeted by the campaign, and with whom people converse, along with several other campaign-relevant and study-relevant variables. The implications of these findings for future research are discussed.

How campaigns polarize the electorate

DEFF Research Database (Denmark)

Hansen, Kasper M.; Kosiara-Pedersen, Karina

2017-01-01

The minimal effect theory of campaign studies stipulates that intense political competition during campaigns assures and reinforces the initial party choice of the electorate. We find that this reinforcement is two-fold. During the campaign, the party preference of the voters’ in-group party...... an increase in their preference for their most preferred party and a decrease for their least liked party as the campaign progresses. These trends show that the political campaign polarizes the electorate by increasing the affective distance between in-group party and out-group party preferences, thereby...... resulting in stronger political polarization after the campaign than before the campaign. The data utilized in this study is a large six-wave panel-study of Danish voters’ party preferences during the Danish parliamentary election of 2011. Thus, the analysis provides evidence of the minimal effect theory...

Open-Loop Performance of COBALT Precision Landing Payload on a Commercial Sub-Orbital Rocket

Science.gov (United States)

Restrepo, Carolina I.; Carson, John M., III; Amzajerdian, Farzin; Seubert, Carl R.; Lovelace, Ronney S.; McCarthy, Megan M.; Tse, Teming; Stelling, Richard; Collins, Steven M.

2018-01-01

An open-loop flight test campaign of the NASA COBALT (CoOperative Blending of Autonomous Landing Technologies) platform was conducted onboard the Masten Xodiac suborbital rocket testbed. The COBALT platform integrates NASA Guidance, Navigation and Control (GN&C) sensing technologies for autonomous, precise soft landing, including the Navigation Doppler Lidar (NDL) velocity and range sensor and the Lander Vision System (LVS) Terrain Relative Navigation (TRN) system. A specialized navigation filter running onboard COBALT fuses the NDL and LVS data in real time to produce a navigation solution that is independent of GPS and suitable for future, autonomous, planetary, landing systems. COBALT was a passive payload during the open loop tests. COBALT's sensors were actively taking data and processing it in real time, but the Xodiac rocket flew with its own GPS-navigation system as a risk reduction activity in the maturation of the technologies towards space flight. A future closed-loop test campaign is planned where the COBALT navigation solution will be used to fly its host vehicle.

Collision Repair Campaign

Science.gov (United States)

The Collision Repair Campaign targets meaningful risk reduction in the Collision Repair source category to reduce air toxic emissions in their communities. The Campaign also helps shops to work towards early compliance with the Auto Body Rule.

Accuracy assessment of high-rate GPS measurements for seismology

Science.gov (United States)

Elosegui, P.; Davis, J. L.; Ekström, G.

2007-12-01

Analysis of GPS measurements with a controlled laboratory system, built to simulate the ground motions caused by tectonic earthquakes and other transient geophysical signals such as glacial earthquakes, enables us to assess the technique of high-rate GPS. The root-mean-square (rms) position error of this system when undergoing realistic simulated seismic motions is 0.05~mm, with maximum position errors of 0.1~mm, thus providing "ground truth" GPS displacements. We have acquired an extensive set of high-rate GPS measurements while inducing seismic motions on a GPS antenna mounted on this system with a temporal spectrum similar to real seismic events. We found that, for a particular 15-min-long test event, the rms error of the 1-Hz GPS position estimates was 2.5~mm, with maximum position errors of 10~mm, and the error spectrum of the GPS estimates was approximately flicker noise. These results may however represent a best-case scenario since they were obtained over a short (~10~m) baseline, thereby greatly mitigating baseline-dependent errors, and when the number and distribution of satellites on the sky was good. For example, we have determined that the rms error can increase by a factor of 2--3 as the GPS constellation changes throughout the day, with an average value of 3.5~mm for eight identical, hourly-spaced, consecutive test events. The rms error also increases with increasing baseline, as one would expect, with an average rms error for a ~1400~km baseline of 9~mm. We will present an assessment of the accuracy of high-rate GPS based on these measurements, discuss the implications of this study for seismology, and describe new applications in glaciology.

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.

Why do GPs leave direct patient care and what might help to retain them? A qualitative study of GPs in South West England.

Science.gov (United States)

Sansom, Anna; Terry, Rohini; Fletcher, Emily; Salisbury, Chris; Long, Linda; Richards, Suzanne H; Aylward, Alex; Welsman, Jo; Sims, Laura; Campbell, John L; Dean, Sarah G

2018-01-10

To identify factors influencing general practitioners' (GPs') decisions about whether or not to remain in direct patient care in general practice and what might help to retain them in that role. Qualitative, in-depth, individual interviews exploring factors related to GPs leaving, remaining in and returning to direct patient care. South West England, UK. 41 GPs: 7 retired; 8 intending to take early retirement; 11 who were on or intending to take a career break; 9 aged under 50 years who had left or were intending to leave direct patient care and 6 who were not intending to leave or to take a career break. Plus 19 stakeholders from a range of primary care-related professional organisations and roles. Reasons for leaving direct patient care were complex and based on a range of job-related and individual factors. Three key themes underpinned the interviewed GPs' thinking and rationale: issues relating to their personal and professional identity and the perceived value of general practice-based care within the healthcare system; concerns regarding fear and risk, for example, in respect of medical litigation and managing administrative challenges within the context of increasingly complex care pathways and environments; and issues around choice and volition in respect of personal social, financial, domestic and professional considerations. These themes provide increased understanding of the lived experiences of working in today's National Health Service for this group of GPs. Future policies and strategies aimed at retaining GPs in direct patient care should clarify the role and expectations of general practice and align with GPs' perception of their own roles and identity; demonstrate to GPs that they are valued and listened to in planning delivery of the UK healthcare; target GPs' concerns regarding fear and risk, seeking to reduce these to manageable levels and give GPs viable options to support them to remain in direct patient care. © Article author(s) (or their

Fundamentals of GPS Receivers A Hardware Approach

CERN Document Server

Doberstein, Dan

2012-01-01

While much of the current literature on GPS receivers is aimed at those intimately familiar with their workings, this volume summarizes the basic principles using as little mathematics as possible, and details the necessary specifications and circuits for constructing a GPS receiver that is accurate to within 300 meters. Dedicated sections deal with the features of the GPS signal and its data stream, the details of the receiver (using a hybrid design as exemplar), and more advanced receivers and topics including time and frequency measurements. Later segments discuss the Zarlink GPS receiver chip set, as well as providing a thorough examination of the TurboRogue receiver, one of the most accurate yet made. Guiding the reader through the concepts and circuitry, from the antenna to the solution of user position, the book’s deployment of a hybrid receiver as a basis for discussion allows for extrapolation of the core ideas to more complex, and more accurate designs. Digital methods are used, but any analogue c...

Exploring female GPs' perceptions about medical leadership.

Science.gov (United States)

Price, Karen; Clearihan, Lynette

2015-06-01

Women are increasingly entering the Australian general practice workforce. This study aims to explore female general practitioners' (GPs') perceptions of possible barriers to leadership and professional roles in the workforce. A purposive, convenience sample of 30 female GPs in active practice was approached in February, 2012. An anonymous, pa-per-based, semi-quantitative survey sought to identify participation and leadership confidence within general practice in a number of professional roles. The top two barriers participants identified for after-hours medical meetings were energy to attend and geographical location. For after-hours care, the top two barriers identified were energy and self-motivation. Few participants aspired to 'leadership' activities. 'Medical mentoring' was most likely to attract them into leadership. It is important female GPs' perspectives are explored in general practice. This small survey suggests further studies are needed in the importance of energy limitations and lack of self-confidence in restricting female GPs' capacity to fully engage in professional roles.

GPS Receivers Use-Case Information : GPS Adjacent Band Compatibility Assessment Workshop

Science.gov (United States)

2014-09-18

Topics 1. Background. 2. Use Case Template. 3. Description of Submitted UseCases from DOT Extended Pos/Nav Working Group. 4. Utilization of UseCase Information. 5. Request of Information for Additional UseCases from GPS Receiver Manufacturer...

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

Science.gov (United States)

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

1997-01-01

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

Radon campaigns. Status report 2008; Radontalkoot. Tilannekatsaus 2008

Energy Technology Data Exchange (ETDEWEB)

Arvela, H.; Valmari, T.; Reisbacka, H.; Niemelae, H.; Oinas, T.; Maekelaeinen, I.; Laitinen-Sorvari, R.

2008-12-15

Radon campaigns aim at activating citizens to make indoor radon measurements and remediation as well as increasing the common awareness of indoor radon questions. Indoor radon increases the risk of lung cancer. Through radon campaigns Radiation and Nuclear Safety Authority (STUK) also promotes the attainment of those goals that the Ministry of Social Affairs and Health has set for municipal authorities in Finland for prevention of the harmful effects of radon. The Ministry of Social Affairs and Health supports this campaign. Radon campaigns were started in autumn 2003. By autumn 2008 the campaigns have been organised already in 64 regions altogether in 160 municipalities. In some municipalities they have already arranged two campaigns. Altogether 14 100 houses have been measured and in 2 100 of these the action limit of radon remediation 400 Bq / m3 has been exceeded. When participating in radon campaigns the house owners receive a special offer on radon detectors with a reduced price. In 2008 a new practice was introduced where the campaign advertisements were distributed by mail to low-rise residential houses in a certain region. The advertisement includes an order / deposit slip with postage paid that the house owner can send directly to STUK to easily make an order for radon measurement. In the previous radon campaigns in 2003 - 2007 the municipal authorities collected the orders from house owners and distributed later the radon detectors. The radon concentrations measured in the campaign regions have exceeded the action limit of 400 Bq / m3 in 0 - 39% of houses, depending on the region. The total of 15% of all measurements made exceeded this limit. The remediation activities have been followed by sending a special questionnaire on remedies performed to the house owners. In 2006 - 2007 a questionnaire was sent to those households where the radon concentration of 400 Bq / m3 was exceeded during the two first campaign seasons. Among the households that replied

Progress in SLR-GPS co-location at San Juan (Argentina) station

Science.gov (United States)

Luis, Hernan; Rojas, Alvis; Adarvez, Sonia; Quinteros, Johana; Cobos, Pablo; Aracena, Andrés; Pacheco, Ana M.; Podestá, Ricardo; Actis, Eloy V.; Li, Jinzeng; Yin, Zhiqiang; Wang, Rui; Huang, Dongping; Márquez, Raúl

2012-08-01

From February, 2006, performing a Cooperation Agreement with National Astronomical Observatories of China (NAOC) of the Chinese Academy of Sciences (CAS), Observatorio Astronómico Félix Aguilar (OAFA) of Universidad Nacional de San Juan (UNSJ) is operating a SLR System (ILRS 7406 Station). From the beginning of 2012 a GPS Aztech - Micro Z CGRS is operative at the same place, which made the SLR - GPS co - location possible. The prior objective is to reach co - location between both techniques, so the Station became of 1st order in ITRF net. For that we study and adopt an appropriate strategy to select and place Survey Control Points that ensures higher precision in determination of 3D vectors between the selected reference point s. Afterwards we perform translocation tasks of receptor and antenna checking that the GPS verifies builder standards. Then we design and compensate survey control network, by means of software of our own draught. We expect to obtain definitive local ties with precision better than 3 mm, as suggested by IERS for co - located stations. There are very few stations with co - located spatial techniques in the Southern Hemisphere, so it is of great importance to have one in Argentina for improve our participation in IERS on the new realizations of ITRF from now on.

Earth tide effects on kinematic/static GPS positioning in Denmark and Greenland

DEFF Research Database (Denmark)

Xu, G.C.; Knudsen, Per

2000-01-01

A detailed Study of the Earth tide effects on the GPS kinematic/static positioning is presented in this paper by using theoretical Earth tide computation and practical GPS data processing. Tidal effects could reach up to 30 cm in Denmark and Greenland depending on the measuring time...... and the position of reference station. With a baseline less than 80 km, the difference of the Earth tide effects could reach more than 5 mm. So, in precise applications of GPS positioning, the Earth tide effect has to be taken into account even for a relative small local GPS network. Several examples are given...... for demonstrating that the Earth tide effects can be viewed by GPS surveying. They are given through static GPS data static processing, static GPS data kinematic processing, and airborne kinematic GPS data processing. In these cases, the Earth tide effects can be subtracted from the GPS results. The determination...

A qualitative study of GPs' and PCO stakeholders' views on the importance and influence of cost on prescribing.

Science.gov (United States)

Prosser, Helen; Walley, Tom

2005-03-01

With prescribing expenditure rising and evidence of prescribing costs variation, general practitioners (GPs) in the UK are under increasing pressure to contain spending. The introduction of cash-limited, unified budgets and increased monitoring of prescribing within Primary Care Organizations (PCO) are intended to increase efficiency and enhance GPs financial responsibility. Whilst GPs regularly receive data on the costs of their prescribing and also performance against a set prescribing budget, little is known about the extent to which GPs take cost into account in their prescribing decisions. This study undertook a qualitative exploration of the attitudes of various stakeholders on the relative importance and influence of cost on general practice prescribing. In order to explore a plurality of perspectives, data were obtained from focus groups and a series of individual semi-structured interviews with GPs and key PCO stakeholders. The data suggest that although almost all GPs believed costs should be taken into account when prescribing, there was great variation in the extent to which this was applied and to how sensitive GPs were to costs. Cost was secondary to clinical effectiveness and safety, whilst individual patient need was emphasized above other forms of rationality or notions of opportunity costs. Conflict was apparent between a PCO policy of cost-containment and GPs' resistance to cost-cutting. GPs largely applied simple cost-minimization while cost-consideration was undermined by contextual factors. Implications for research and policy are discussed.

Campaigns and counter campaigns: reactions on Twitter to e-cigarette education.

Science.gov (United States)

Allem, Jon-Patrick; Escobedo, Patricia; Chu, Kar-Hai; Soto, Daniel W; Cruz, Tess Boley; Unger, Jennifer B

2017-03-01

Social media present opportunities for public health departments to galvanise interest in health issues. A challenge is creating content that will resonate with target audiences, and determining reactions to educational material. Twitter can be used as a real-time surveillance system to capture individuals' immediate reactions to education campaigns and such information could lead to better campaigns in the future. A case study testing Twitter's potential presented itself when the California Department of Public Health launched its 'Still Blowing Smoke' media campaign about the potential harmful effects of e-cigarettes. Pro-e-cigarette advocacy groups, in response, launched a counter campaign titled 'Not Blowing Smoke'. This study tracked the popularity of the two campaigns on Twitter, analysed the content of the messages and determined who was involved in these discussions. The study period was from 22 March 2015 to 27 June 2015. A stratified sampling procedure supplied 2192 tweets for analysis. Content analysis identified pro, anti and neutral e-cigarette tweets, and five additional themes: Marketing Elements, Money, Regulation/propaganda, Health, and Other. Metadata were analysed to obtain additional information about Twitter accounts. 'Not Blowing Smoke' was referenced more frequently than 'Still Blowing Smoke' on Twitter. Messages commonly objected to government regulation of e-cigarettes, refuted claims that e-cigarette manufactures were aligned with big tobacco, and touted the health benefits of e-cigarette use. E-cigarette companies and vape shops used campaign slogans to communicate with customers on Twitter. Findings showed the time dynamics of Twitter and the possibility for real-time monitoring of education campaigns. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

GPS phase scintillation during the geomagnetic storm of March 17, 2015: The relation to auroral electrojet currents

DEFF Research Database (Denmark)

Prikryl, Paul; Ghoddousi-Fard, Reza; Connors, Martin

and magnetometers. GPS phase scintillation index is computed for L1 signal sampled at the rate of 50 Hz by specialized GPS scintillation receivers of the Expanded Canadian High Arctic Ionospheric Network (ECHAIN). To further extend the geographic coverage, the phasescintillation proxy index is obtained from......Ionospheric irregularities cause rapid fluctuations of radio wave amplitude and phase that candegrade GPS positional accuracy and affect performance of radio communication and navigation systems. The ionosphere becomes particularly disturbed during geomagnetic storms caused by impacts of coronal...... mass ejections compounded by high-speed plasma streams from coronal holes. Geomagnetic storm of March 17, 2015 was the largest in the current solar cycle. The high-latitude ionosphere dynamics is studied using arrays of ground-based instruments including GPS receivers, HF radars, ionosondes, riometers...

Demonstration of coherent Doppler lidar for navigation in GPS-denied environments

Science.gov (United States)

Amzajerdian, Farzin; Hines, Glenn D.; Pierrottet, Diego F.; Barnes, Bruce W.; Petway, Larry B.; Carson, John M.

2017-05-01

A coherent Doppler lidar has been developed to address NASA's need for a high-performance, compact, and cost-effective velocity and altitude sensor onboard its landing vehicles. Future robotic and manned missions to solar system bodies require precise ground-relative velocity vector and altitude data to execute complex descent maneuvers and safe, soft landing at a pre-designated site. This lidar sensor, referred to as a Navigation Doppler Lidar (NDL), meets the required performance of the landing missions while complying with vehicle size, mass, and power constraints. Operating from up to four kilometers altitude, the NDL obtains velocity and range precision measurements reaching 2 cm/sec and 2 meters, respectively, dominated by the vehicle motion. Terrestrial aerial vehicles will also benefit from NDL data products as enhancement or replacement to GPS systems when GPS is unavailable or redundancy is needed. The NDL offers a viable option to aircraft navigation in areas where the GPS signal can be blocked or jammed by intentional or unintentional interference. The NDL transmits three laser beams at different pointing angles toward the ground to measure range and velocity along each beam using a frequency modulated continuous wave (FMCW) technique. The three line-of-sight measurements are then combined in order to determine the three components of the vehicle velocity vector and its altitude relative to the ground. This paper describes the performance and capabilities that the NDL demonstrated through extensive ground tests, helicopter flight tests, and onboard an autonomous rocket-powered test vehicle while operating in closedloop with a guidance, navigation, and control (GN and C) system.

GPS Attitude Determination for Launch Vehicles, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Toyon Research Corporation proposes to develop a family of compact, low-cost GPS-based attitude (GPS/A) sensors for launch vehicles. In order to obtain 3-D attitude...

News Media Framing of Negative Campaigning

DEFF Research Database (Denmark)

Pedersen, Rasmus Tue

2014-01-01

that news coverage of negative campaigning does apply the strategic game frame to a significantly larger degree than articles covering positive campaigning. This finding has significant implications for campaigning politicians and for scholars studying campaign and media effects.......News media coverage of election campaigns is often characterized by use of the strategic game frame and a focus on politicians’ use of negative campaigning. However, the exact relationship between these two characteristics of news coverage is largely unexplored. This article theorizes that consumer...... demand and norms of journalistic independence might induce the news media outlets to cover negative campaigning with a strategic game frame. A comprehensive content analysis based on several newspaper types, several election campaigns, and several different measurements of media framing confirms...

The Sprite 2003 Campaign

DEFF Research Database (Denmark)

Neubert, T.; Laursen, S.; Rasmussen, I. L.

2003-01-01

During the northern hemisphere summer of 2003, from July 18 to September 18, a sprite observation campaign was conducted with measurements from Southern Europe, coordinated with measurements from the magnetically conjugate region in South Africa. The goal of the campaign was to investigate...... emissions. The presentation will give an overview of the campaign, the meteorological conditions, and present some first results....

Coarse Initial Orbit Determination for a Geostationary Satellite Using Single-Epoch GPS Measurements

Directory of Open Access Journals (Sweden)

Ghangho Kim

2015-04-01

Full Text Available A practical algorithm is proposed for determining the orbit of a geostationary orbit (GEO satellite using single-epoch measurements from a Global Positioning System (GPS receiver under the sparse visibility of the GPS satellites. The algorithm uses three components of a state vector to determine the satellite’s state, even when it is impossible to apply the classical single-point solutions (SPS. Through consideration of the characteristics of the GEO orbital elements and GPS measurements, the components of the state vector are reduced to three. However, the algorithm remains sufficiently accurate for a GEO satellite. The developed algorithm was tested on simulated measurements from two or three GPS satellites, and the calculated maximum position error was found to be less than approximately 40 km or even several kilometers within the geometric range, even when the classical SPS solution was unattainable. In addition, extended Kalman filter (EKF tests of a GEO satellite with the estimated initial state were performed to validate the algorithm. In the EKF, a reliable dynamic model was adapted to reduce the probability of divergence that can be caused by large errors in the initial state.

Coarse Initial Orbit Determination for a Geostationary Satellite Using Single-Epoch GPS Measurements

Science.gov (United States)

Kim, Ghangho; Kim, Chongwon; Kee, Changdon

2015-01-01

A practical algorithm is proposed for determining the orbit of a geostationary orbit (GEO) satellite using single-epoch measurements from a Global Positioning System (GPS) receiver under the sparse visibility of the GPS satellites. The algorithm uses three components of a state vector to determine the satellite’s state, even when it is impossible to apply the classical single-point solutions (SPS). Through consideration of the characteristics of the GEO orbital elements and GPS measurements, the components of the state vector are reduced to three. However, the algorithm remains sufficiently accurate for a GEO satellite. The developed algorithm was tested on simulated measurements from two or three GPS satellites, and the calculated maximum position error was found to be less than approximately 40 km or even several kilometers within the geometric range, even when the classical SPS solution was unattainable. In addition, extended Kalman filter (EKF) tests of a GEO satellite with the estimated initial state were performed to validate the algorithm. In the EKF, a reliable dynamic model was adapted to reduce the probability of divergence that can be caused by large errors in the initial state. PMID:25835299

Application and Limitations of GPS Radio Occultation (GPS-RO) Data for Atmospheric Boundary Layer Height Detection over the Arctic.

Science.gov (United States)

Ganeshan, M.; Wu, D. L.

2014-12-01

Due to recent changes in the Arctic environment, it is important to monitor the atmospheric boundary layer (ABL) properties over the Arctic Ocean, especially to explore the variability in ABL clouds (such as sensitivity and feedback to sea ice loss). For example, radiosonde and satellite observations of the Arctic ABL height (and low-cloud cover) have recently suggested a positive response to sea ice loss during October that may not occur during the melt season (June-September). Owing to its high vertical and spatiotemporal resolution, an independent ABL height detection algorithm using GPS Radio Occultation (GPS-RO) refractivity in the Arctic is explored. Similar GPS-RO algorithms developed previously typically define the level of the most negative moisture gradient as the ABL height. This definition is favorable for subtropical oceans where a stratocumulus-topped ABL is often capped by a layer of sharp moisture lapse rate (coincident with the temperature inversion). The Arctic Ocean is also characterized by stratocumulus cloud cover, however, the specific humidity does not frequently decrease in the ABL capping inversion. The use of GPS-RO refractivity for ABL height retrieval therefore becomes more complex. During winter months (December-February), when the total precipitable water in the troposphere is a minimum, a fairly straightforward algorithm for ABL height retrieval is developed. The applicability and limitations of this method for other seasons (Spring, Summer, Fall) is determined. The seasonal, interannual and spatial variability in the GPS-derived ABL height over the Arctic Ocean, as well as its relation to the underlying surface (ice vs. water), is investigated. The GPS-RO profiles are also explored for the evidence of low-level moisture transport in the cold Arctic environment.

Penerapan Teknologi GPS Tracker Untuk Identifikasi Kondisi Traffik Jalan Raya

Directory of Open Access Journals (Sweden)

IM. O. Widyantara

2015-06-01

Full Text Available Real time tracking system technology has been made possible by integrating three technologies, namely global positioning system (GPS, database technologies such as geographic information system (GIS and mobile telecommunications technologies such as general packet radio service (GPRS. This paper has proposed a vehicle tracking mechanism based on GPS tracker to build a real-time traffic information system. A GPS server is built to process data of position and speed of the vehicle for further processed into vehicle traffic information. The Server and GPS tracker is designed to communicate using GPRS services in real time. Furthermore, the server processes the data from the GPS tracker into traffic information such as traffic jam, dense, medium and smoothly. Test results showed that the GPS server is able to visualize the real position of the vehicle and is able to decide the category of traffic information in real time.

GPs' mental wellbeing and psychological resources: a cross-sectional survey.

Science.gov (United States)

Murray, Marylou Anna; Cardwell, Chris; Donnelly, Michael

2017-08-01

The negative impact of work has been the traditional focus of GP surveys. We know little about GP positive mental health and psychological resources. To profile and contextualise GP positive mental health and personal psychological resources. Cross-sectional survey of GPs working in Northern Ireland (NI). A questionnaire comprising the Warwick Edinburgh Mental Wellbeing Scale (WEMWBS) and measures of resilience, optimism, self-efficacy, and hope, and sociodemographic information was posted to 400 GPs randomly selected from a publicly available GP register. The response rate was 55% (n = 221 out of 400). Mean value for GP wellbeing (WEMWBS) was 50.2 (standard deviation [SD] 8) compared to UK vets 48.8 (SD 9), UK teachers 47.2 (SD 9), and the population of NI 50.8 (SD 9). After adjustment for confounding, mean WEMWBS was 2.4 units (95% CI = 0.02 to 4.7) higher in female GPs than males ( P = 0.05), and 4.0 units (95% CI = 0.8 to 7.3) higher in GPs ≥55 years than GPs ≤44 years ( P = 0.02). Optimism was 1.1 units higher in female GPs than male GPs (95% CI = 0.1 to 2.0), and 1.56 units higher in GPs ≥55 years (95% CI = 0.2 to 2.9) than in those ≤44 years. Hope was 3 units higher in GPs ≥55 years (95% CI = 0.4 to 5.7) than in those aged 45-54 years. Correlation between WEMWBS and psychological resources was highest with hope ( r = 0.65, P mental health that are comparable to the local population and better than other occupational groups, such as vets and teachers. Male and younger GPs may have most to gain from wellbeing interventions. © British Journal of General Practice 2017.

The impact of GPS receiver modifications and ionospheric activity on Swarm baseline determination

Science.gov (United States)

Mao, X.; Visser, P. N. A. M.; van den IJssel, J.

2018-05-01

The European Space Agency (ESA) Swarm mission is a satellite constellation launched on 22 November 2013 aiming at observing the Earth geomagnetic field and its temporal variations. The three identical satellites are equipped with high-precision dual-frequency Global Positioning System (GPS) receivers, which make the constellation an ideal test bed for baseline determination. From October 2014 to August 2016, a number of GPS receiver modifications and a new GPS Receiver Independent Exchange Format (RINEX) converter were implemented. Moreover, the on-board GPS receiver performance has been influenced by the ionospheric scintillations. The impact of these factors is assessed for baseline determination of the pendulum formation flying Swarm-A and -C satellites. In total 30 months of data - from 15 July 2014 to the end of 2016 - is analyzed. The assessment includes analysis of observation residuals, success rate of GPS carrier phase ambiguity fixing, a consistency check between the so-called kinematic and reduced-dynamic baseline solution, and validations of orbits by comparing with Satellite Laser Ranging (SLR) observations. External baseline solutions from The German Space Operations Center (GSOC) and Astronomisches Institut - Universität Bern (AIUB) are also included in the comparison. Results indicate that the GPS receiver modifications and RINEX converter changes are effective to improve the baseline determination. This research eventually shows a consistency level of 9.3/4.9/3.0 mm between kinematic and reduced-dynamic baselines in the radial/along-track/cross-track directions. On average 98.3% of the epochs have kinematic solutions. Consistency between TU Delft and external reduced-dynamic baseline solutions is at a level of 1 mm level in all directions.

Strategic campaigns and redistributive politics

DEFF Research Database (Denmark)

Schultz, Christian

2007-01-01

The article investigates strategic, informative campaigning by two parties when politics concern redistribution. Voters are uncertain about whether parties favour special groups. Parties will target campaigns on groups where most votes are gained by informing about policies. In equilibrium......, campaigning will be most intensive in groups where the uncertainty is largest and where voters are most mobile, most likely to vote, most receptive to campaigns and relatively uninformed initially. These groups will become more informed about policy. Parties will therefore gain more votes by treating...... these groups well so these groups will gain from strategic campaigning. Welfare effects are assessed...

Real-time GPS seismology using a single receiver: method comparison, error analysis and precision validation

Science.gov (United States)

Li, Xingxing

2014-05-01

displacements is accompanied by a drift due to the potential uncompensated errors. Li et al. (2013) presented a temporal point positioning (TPP) method to quickly capture coseismic displacements with a single GPS receiver in real-time. The TPP approach can overcome the convergence problem of precise point positioning (PPP), and also avoids the integration and de-trending process of the variometric approach. The performance of TPP is demonstrated to be at few centimeters level of displacement accuracy for even twenty minutes interval with real-time precise orbit and clock products. In this study, we firstly present and compare the observation models and processing strategies of the current existing single-receiver methods for real-time GPS seismology. Furthermore, we propose several refinements to the variometric approach in order to eliminate the drift trend in the integrated coseismic displacements. The mathematical relationship between these methods is discussed in detail and their equivalence is also proved. The impact of error components such as satellite ephemeris, ionospheric delay, tropospheric delay, and geometry change on the retrieved displacements are carefully analyzed and investigated. Finally, the performance of these single-receiver approaches for real-time GPS seismology is validated using 1 Hz GPS data collected during the Tohoku-Oki earthquake (Mw 9.0, March 11, 2011) in Japan. It is shown that few centimeters accuracy of coseismic displacements is achievable. Keywords: High-rate GPS; real-time GPS seismology; a single receiver; PPP; variometric approach; temporal point positioning; error analysis; coseismic displacement; fault slip inversion;

Arctic tides from GPS on sea ice

DEFF Research Database (Denmark)

Kildegaard Rose, Stine; Skourup, Henriette; Forsberg, René

The presence of sea-ice in the Arctic Ocean plays a significant role in the Arctic climate. Sea ice dampens the ocean tide amplitude with the result that global tidal models which use only astronomical data perform less accurately in the polar regions. This study presents a kinematic processing o......-gauges and altimetry data. Furthermore, we prove that the geodetic reference ellipsoid WGS84, can be interpolated to the tidal defined zero level by applying geophysical corrections to the GPS data....

Twitter Campaigns Around the Fifth IPCC Report: Campaign Spreading, Shared Hashtags, and Separate Communities

NARCIS (Netherlands)

Holmberg, K.; Hellsten, I.

2016-01-01

In this article, we analyzed campaigning on Twitter around the publication of the fifth Intergovernmental Panel for Climate Change (IPCC) Working Group 1 report in September, 2013. In particular, we analyzed how participation in a specific campaign and use of hashtags connected to the campaign

Real-Time Single-Frequency GPS/MEMS-IMU Attitude Determination of Lightweight UAVs

Science.gov (United States)

Eling, Christian; Klingbeil, Lasse; Kuhlmann, Heiner

2015-01-01

In this paper, a newly-developed direct georeferencing system for the guidance, navigation and control of lightweight unmanned aerial vehicles (UAVs), having a weight limit of 5 kg and a size limit of 1.5 m, and for UAV-based surveying and remote sensing applications is presented. The system is intended to provide highly accurate positions and attitudes (better than 5 cm and 0.5∘) in real time, using lightweight components. The main focus of this paper is on the attitude determination with the system. This attitude determination is based on an onboard single-frequency GPS baseline, MEMS (micro-electro-mechanical systems) inertial sensor readings, magnetic field observations and a 3D position measurement. All of this information is integrated in a sixteen-state error space Kalman filter. Special attention in the algorithm development is paid to the carrier phase ambiguity resolution of the single-frequency GPS baseline observations. We aim at a reliable and instantaneous ambiguity resolution, since the system is used in urban areas, where frequent losses of the GPS signal lock occur and the GPS measurement conditions are challenging. Flight tests and a comparison to a navigation-grade inertial navigation system illustrate the performance of the developed system in dynamic situations. Evaluations show that the accuracies of the system are 0.05∘ for the roll and the pitch angle and 0.2∘ for the yaw angle. The ambiguities of the single-frequency GPS baseline can be resolved instantaneously in more than 90% of the cases. PMID:26501281

77 FR 70421 - GPS Satellite Simulator Control Working Group Meeting

Science.gov (United States)

2012-11-26

... DEPARTMENT OF DEFENSE Department of the Air Force GPS Satellite Simulator Control Working Group Meeting AGENCY: Space and Missile Systems Center, Global Positioning Systems (GPS) Directorate, Department of the Air Force, DoD. ACTION: Meeting Notice. SUMMARY: This meeting notice is to inform GPS...

Outcome prediction in gastroschisis - The gastroschisis prognostic score (GPS) revisited.

Science.gov (United States)

Puligandla, Pramod S; Baird, Robert; Skarsgard, Eric D; Emil, Sherif; Laberge, Jean-Martin

2017-05-01

The GPS enables risk stratification for gastroschisis and helps discriminate low from high morbidity groups. The purpose of this study was to revalidate GPS's characterization of a high morbidity group and to quantify relationships between the GPS and outcomes. With REB approval, complete survivor data from a national gastroschisis registry was collected. GPS bowel injury scoring was revalidated excluding the initial inception/validation cohorts (>2011). Length of stay (LOS), 1st enteral feed days (dFPO), TPN days (dTPN), and aggregate complications (COMP) were compared between low and high morbidity risk groups. Mathematical relationships between outcomes and integer increases in GPS were explored using the entire cohort (2005-present). Median (range) LOS, dPO, and dTPN for the entire cohort (n=849) was 36 (26,62), 13 (9,18), and 27 (20,46) days, respectively. High-risk patients (GPS≥2; n=80) experienced significantly worse outcomes than low risk patients (n=263). Each integer increase in GPS was associated with increases in LOS and dTPN by 16.9 and 12.7days, respectively (pGPS effectively discriminates low from high morbidity risk groups. Within the high risk group, integer increases in GPS produce quantitatively differentiated outcomes which may guide initial counseling and resource allocation. IIb. Copyright © 2017 Elsevier Inc. All rights reserved.

Understanding quit decisions in primary care: a qualitative study of older GPs.

Science.gov (United States)

Sansom, Anna; Calitri, Raff; Carter, Mary; Campbell, John

2016-02-19

To investigate the reasons behind intentions to quit direct patient care among experienced general practitioners (GPs) aged 50-60 years. Qualitative study based on semistructured interviews with GPs in the South West region of England. Transcribed interviews were analysed thematically. 23 GPs aged 50-60 years: 3 who had retired from direct patient care before age 60, and 20 who intended to quit direct patient care within the next 5 years. The analysis identified four key themes: early retirement is a viable option for many GPs; GPs have employment options other than undertaking direct patient care; GPs report feeling they are doing an (almost) undoable job; and GPs may have other aspirations that pull them away from practice. Findings from this study confirmed those from earlier research, with high workload, ageing and health, family and domestic life, and organisational change all influencing GPs' decisions about when to retire/quit direct patient care. However, in addition, GPs expressed feelings of insecurity and uncertainty regarding the future of general practice, low morale, and issues regarding accountability (appraisal and revalidation) and governance. Suggestions about how to help retain GPs within the active clinical workforce were offered, covering individual, practice and organisational levels. This research highlights aspects of the current professional climate for GPs that are having an impact on retirement decisions. Any future changes to policy or practice to help retain experienced GPs will benefit from this informed understanding of GPs' views. Key factors to take into account include: making the GP workload more manageable; managing change sympathetically; paying attention to GPs' own health; improving confidence in the future of general practice; and improving GP morale. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Relation of decorrelated transionospheric GPS signal fluctuations from two stations in the northern anomaly crest region with equatorial ionospheric dynamics

Science.gov (United States)

Paul, K. S.; Paul, A.

2017-05-01

The ionosphere around the northern crest of the equatorial ionization anomaly (EIA) and beyond exhibits rapid temporal as well as spatial development of ionization density irregularities during postsunset hours. A GPS campaign was conducted during September 2012 and April 2013 from the Institute of Radio Physics and Electronics, Calcutta (22.58°N, 88.38°E geographic; magnetic dip: 32°N), and North Bengal University (NBU), Siliguri (26.72°N, 88.39°E geographic, magnetic dip: 39.49°N) in India in order to assess and quantify differences, if any, in the nature of carrier to noise ratio (C/N0) fluctuations observed on the same satellite link around the same time interval from these stations. Significant decorrelation of the received signals was found when tracking the same satellite vehicle (SV) link from these stations during periods of scintillations. Low values of correlation coefficient of C/N0 at L1 frequency recorded on the same SV link at these two stations were found to correspond with high irregularity characteristic velocities. North-south spatial displacement rates of the impact of ionospheric irregularities were calculated based on coordinated GPS observations which followed an increasing trend with irregularity characteristic velocities measured at VHF. Values of characteristic velocities in excess of 36 m/s were also found to result in large receiver position deviations 3.5-4.0 m during periods of scintillations. Information related to time lag associated with occurrence of scintillations on the same SV link observed from two stations could be useful for improving performance of transionospheric satellite-based position determination techniques.

En Billig GPS Data Analyse Platform

DEFF Research Database (Denmark)

Andersen, Ove; Christiansen, Nick; Larsen, Niels T.

2011-01-01

Denne artikel præsenterer en komplet software platform til analyse af GPS data. Platformen er bygget udelukkende vha. open-source komponenter. De enkelte komponenter i platformen beskrives i detaljer. Fordele og ulemper ved at bruge open-source diskuteres herunder hvilke IT politiske tiltage, der...... organisationer med et digitalt vejkort og GPS data begynde at lave trafikanalyser på disse data. Det er et krav, at der er passende IT kompetencer tilstede i organisationen....

78 FR 63459 - GPS Satellite Simulator Control Working Group Meeting

Science.gov (United States)

2013-10-24

... DEPARTMENT OF DEFENSE Air Force GPS Satellite Simulator Control Working Group Meeting AGENCY: Department of the Air Force. ACTION: Meeting Notice. SUMMARY: This meeting notice is to inform GPS simulator manufacturers, who supply products to the Department of Defense (DoD), and GPS simulator users, both government...

GPs' perceptions of resilience training: a qualitative study.

Science.gov (United States)

Cheshire, Anna; Hughes, John; Lewith, George; Panagioti, Maria; Peters, David; Simon, Chantal; Ridge, Damien

2017-10-01

GPs are reporting increasing levels of burnout, stress, and job dissatisfaction, and there is a looming GP shortage. Promoting resilience is a key strategy for enhancing the sustainability of the healthcare workforce and improving patient care. To explore GPs' perspectives on the content, context, and acceptability of resilience training programmes in general practice, in order to build more effective GP resilience programmes. This was a qualitative study of the perspectives of GPs currently practising in England. GPs were recruited through convenience sampling, and data were collected from two focus groups ( n = 15) and one-to-one telephone interviews ( n = 7). A semi-structured interview approach was used and data were analysed using thematic analysis. Participants perceived resilience training to be potentially of value in ameliorating workplace stresses. Nevertheless, uncertainty was expressed regarding how best to provide training for stressed GPs who have limited time. Participants suspected that GPs most likely to benefit from resilience training were the least likely to engage, as stress and being busy worked against engagement. Conflicting views were expressed about the most suitable training delivery method for promoting better engagement. Participants also emphasised that training should not only place the focus on the individual, but also focus on organisation issues. A multimodal, flexible approach based on individual needs and learning aims, including resilience workshops within undergraduate training and in individual practices, is likely to be the optimal way to promote resilience. © British Journal of General Practice 2017.

Flight Performance Evaluation of Three GPS Receivers for Sounding Rocket Tracking

Science.gov (United States)

Bull, Barton; Diehl, James; Montenbruck, Oliver; Markgraf, Markus; Bauer, Frank (Technical Monitor)

2002-01-01

In preparation for the European Space Agency Maxus-4 mission, a sounding rocket test flight was carried out at Esrange, near Kiruna, Sweden on February 19, 2001 to validate existing ground facilities and range safety installations. Due to the absence of a dedicated scientific payload, the flight offered the opportunity to test multiple GPS receivers and assess their performance for the tracking of sounding rockets. The receivers included an Ashtech G12 HDMA receiver, a BAE (Canadian Marconi) Allstar receiver and a Mitel Orion receiver. All of them provide C/A code tracking on the L1 frequency to determine the user position and make use of Doppler measurements to derive the instantaneous velocity. Among the receivers, the G12 has been optimized for use under highly dynamic conditions and has earlier been flown successfully on NASA sounding rockets. The Allstar is representative of common single frequency receivers for terrestrial applications and received no particular modification, except for the disabling of the common altitude and velocity constraints that would otherwise inhibit its use for space application. The Orion receiver, finally, employs the same Mitel chipset as the Allstar, but has received various firmware modifications by DLR to safeguard it against signal losses and improve its tracking performance. While the two NASA receivers were driven by a common wrap-around antenna, the DLR experiment made use of a switchable antenna system comprising a helical antenna in the tip of the rocket and two blade antennas attached to the body of the vehicle. During the boost a peak acceleration of roughly l7g's was achieved which resulted in a velocity of about 1100 m/s at the end of the burn. At apogee, the rocket reached an altitude of over 80 km. A detailed analysis of the attained flight data is given together with a evaluation of different receiver designs and antenna concepts.

PRECISE POSITIONING OF UAVS – DEALING WITH CHALLENGING RTK-GPS MEASUREMENT CONDITIONS DURING AUTOMATED UAV FLIGHTS

Directory of Open Access Journals (Sweden)

F. Zimmermann

2017-08-01

Full Text Available For some years now, UAVs (unmanned aerial vehicles are commonly used for different mobile mapping applications, such as in the fields of surveying, mining or archeology. To improve the efficiency of these applications an automation of the flight as well as the processing of the collected data is currently aimed at. One precondition for an automated mapping with UAVs is that the georeferencing is performed directly with cm-accuracies or better. Usually, a cm-accurate direct positioning of UAVs is based on an onboard multi-sensor system, which consists of an RTK-capable (real-time kinematic GPS (global positioning system receiver and additional sensors (e.g. inertial sensors. In this case, the absolute positioning accuracy essentially depends on the local GPS measurement conditions. Especially during mobile mapping applications in urban areas, these conditions can be very challenging, due to a satellite shadowing, non-line-of sight receptions, signal diffraction or multipath effects. In this paper, two straightforward and easy to implement strategies will be described and analyzed, which improve the direct positioning accuracies for UAV-based mapping and surveying applications under challenging GPS measurement conditions. Based on a 3D model of the surrounding buildings and vegetation in the area of interest, a GPS geometry map is determined, which can be integrated in the flight planning process, to avoid GPS challenging environments as far as possible. If these challenging environments cannot be avoided, the GPS positioning solution is improved by using obstruction adaptive elevation masks, to mitigate systematic GPS errors in the RTK-GPS positioning. Simulations and results of field tests demonstrate the profit of both strategies.

Evaluating methods for estimating home ranges using GPS collars: A comparison using proboscis monkeys (Nasalis larvatus).

Science.gov (United States)

Stark, Danica J; Vaughan, Ian P; Ramirez Saldivar, Diana A; Nathan, Senthilvel K S S; Goossens, Benoit

2017-01-01

The development of GPS tags for tracking wildlife has revolutionised the study of home ranges, habitat use and behaviour. Concomitantly, there have been rapid developments in methods for estimating habitat use from GPS data. In combination, these changes can cause challenges in choosing the best methods for estimating home ranges. In primatology, this issue has received little attention, as there have been few GPS collar-based studies to date. However, as advancing technology is making collaring studies more feasible, there is a need for the analysis to advance alongside the technology. Here, using a high quality GPS collaring data set from 10 proboscis monkeys (Nasalis larvatus), we aimed to: 1) compare home range estimates from the most commonly used method in primatology, the grid-cell method, with three recent methods designed for large and/or temporally correlated GPS data sets; 2) evaluate how well these methods identify known physical barriers (e.g. rivers); and 3) test the robustness of the different methods to data containing either less frequent or random losses of GPS fixes. Biased random bridges had the best overall performance, combining a high level of agreement between the raw data and estimated utilisation distribution with a relatively low sensitivity to reduced fixed frequency or loss of data. It estimated the home range of proboscis monkeys to be 24-165 ha (mean 80.89 ha). The grid-cell method and approaches based on local convex hulls had some advantages including simplicity and excellent barrier identification, respectively, but lower overall performance. With the most suitable model, or combination of models, it is possible to understand more fully the patterns, causes, and potential consequences that disturbances could have on an animal, and accordingly be used to assist in the management and restoration of degraded landscapes.

Evaluating methods for estimating home ranges using GPS collars: A comparison using proboscis monkeys (Nasalis larvatus.

Directory of Open Access Journals (Sweden)

Danica J Stark

Full Text Available The development of GPS tags for tracking wildlife has revolutionised the study of home ranges, habitat use and behaviour. Concomitantly, there have been rapid developments in methods for estimating habitat use from GPS data. In combination, these changes can cause challenges in choosing the best methods for estimating home ranges. In primatology, this issue has received little attention, as there have been few GPS collar-based studies to date. However, as advancing technology is making collaring studies more feasible, there is a need for the analysis to advance alongside the technology. Here, using a high quality GPS collaring data set from 10 proboscis monkeys (Nasalis larvatus, we aimed to: 1 compare home range estimates from the most commonly used method in primatology, the grid-cell method, with three recent methods designed for large and/or temporally correlated GPS data sets; 2 evaluate how well these methods identify known physical barriers (e.g. rivers; and 3 test the robustness of the different methods to data containing either less frequent or random losses of GPS fixes. Biased random bridges had the best overall performance, combining a high level of agreement between the raw data and estimated utilisation distribution with a relatively low sensitivity to reduced fixed frequency or loss of data. It estimated the home range of proboscis monkeys to be 24-165 ha (mean 80.89 ha. The grid-cell method and approaches based on local convex hulls had some advantages including simplicity and excellent barrier identification, respectively, but lower overall performance. With the most suitable model, or combination of models, it is possible to understand more fully the patterns, causes, and potential consequences that disturbances could have on an animal, and accordingly be used to assist in the management and restoration of degraded landscapes.

11 CFR 106.3 - Allocation of expenses between campaign and non-campaign related travel.

Science.gov (United States)

2010-01-01

... 11 Federal Elections 1 2010-01-01 2010-01-01 false Allocation of expenses between campaign and non-campaign related travel. 106.3 Section 106.3 Federal Elections FEDERAL ELECTION COMMISSION GENERAL ALLOCATIONS OF CANDIDATE AND COMMITTEE ACTIVITIES § 106.3 Allocation of expenses between campaign and non...

DEVELOPMENT OF A NOVEL GAS PRESSURIZED STRIPPING (GPS)-BASED TECHNOLOGY FOR CO₂ CAPTURE FROM POST-COMBUSTION FLUE GASES Topical Report: Techno-Economic Analysis of GPS-based Technology for CO₂ Capture

Energy Technology Data Exchange (ETDEWEB)

Chen, Shiaoguo

2015-09-30

This topical report presents the techno-economic analysis, conducted by Carbon Capture Scientific, LLC (CCS) and Nexant, for a nominal 550 MWe supercritical pulverized coal (PC) power plant utilizing CCS patented Gas Pressurized Stripping (GPS) technology for post-combustion carbon capture (PCC). Illinois No. 6 coal is used as fuel. Because of the difference in performance between the GPS-based PCC and the MEA-based CO2 absorption technology, the net power output of this plant is not exactly 550 MWe. DOE/NETL Case 11 supercritical PC plant without CO2 capture and Case 12 supercritical PC plant with benchmark MEA-based CO2 capture are chosen as references. In order to include CO2 compression process for the baseline case, CCS independently evaluated the generic 30 wt% MEA-based PCC process together with the CO2 compression section. The net power produced in the supercritical PC plant with GPS-based PCC is 647 MW, greater than the MEA-based design. The levelized cost of electricity (LCOE) over a 20-year period is adopted to assess techno-economic performance. The LCOE for the supercritical PC plant with GPS-based PCC, not considering CO2 transport, storage and monitoring (TS&M), is 97.4 mills/kWh, or 152% of the Case 11 supercritical PC plant without CO2 capture, equivalent to $39.6/tonne for the cost of CO2 capture. GPS-based PCC is also significantly superior to the generic MEA-based PCC with CO2 compression section, whose LCOE is as high as 109.6 mills/kWh.

Age-related differences in working hours among male and female GPs: an SMS-based time use study.

Science.gov (United States)

van Hassel, Daniël; van der Velden, Lud; de Bakker, Dinny; Batenburg, Ronald

2017-12-19

In several countries, the number of hours worked by general practitioners (GPs) has decreased, raising concern about current and impending workforce shortages. This shorter working week has been ascribed both to the feminisation of the workforce and to a younger generation of GPs who prefer more flexible working arrangements. There is, however, limited insight into how the impact of these determinants interact. We investigated the relative importance of differences in GPs' working hours in relation to gender, age, and employment position. An analysis was performed on real-time monitoring data collected by sending SMS text messages to 1051 Dutch GPs, who participated during a 1-week time use study. We used descriptive statistics, independent sample t-tests, and one-way ANOVA analysis to compare the working time of different GP groups. A path analysis was conducted to examine the difference in working time by gender, age, employment position, and their combinations. Female GPs worked significantly fewer hours than their male peers. GPs in their 50s worked the highest number of hours, followed by GPs age 60 and older. GPs younger than 40 worked the lowest number of hours. This relationship between working hours and age was not significantly different for women and men. As shown by path analysis, female GPs consistently worked fewer hours than their male counterparts, regardless of their age and employment position. The relationship between age and working hours was largely influenced by gender and employment position. The variation in working hours among GPs can be explained by the combination of gender, age, and employment position. Gender appears to be the most important predictor as the largest part of the variation in working hours is explained by a direct effect of this variable. It has previously been reported that the difference in working hours between male and female GPs had decreased over time. However, our findings suggest that gender remains a critical

Proposal and realization advertising campaign

OpenAIRE

RYCHLÁ, Marie

2008-01-01

The Bachelor Paper contains proposal and realization advertising campaign, including make charge for cost amount. The advertising campaign is made for chosen product of firm. Advertising campaign is planning by the medium of broadsheet and advertising on the Internet.

RADIOPROTECTION CAMPAIGN AND CARD: EDUCATIONAL STRATEGIES THAT REDUCE CHILDREN'S EXCESSIVE EXPOSURE TO RADIOLOGICAL EXAMS.

Science.gov (United States)

Bernardo, Mônica Oliveira; Almeida, Fernando Antonio de; Morgado, Flavio

2017-01-01

To analyze the results of an initiative aimed at improving the reasonable use of radiological examinations, ensuring their technical quality, implementing a radioprotection campaign that includes training of the professional team, and introducing the radioprotection card for children under 12 years old as a tool for parents and doctors to control children's exposure to radiation. The study was held in a health care insurance system covering 140,000 people. A radioprotection campaign was implemented according to Image Gently • protocols, ensuring the lowest dose of radiation and the quality of examinations, and the radioprotection card was implemented. To assess the effectiveness of these actions, the number of radiological examinations performed at the pediatric emergency room in a period of one year preceding the campaign was compared with the number of radiological examinations performed one year after the campaign. The campaign was well accepted by all professionals, families, and patients involved. In the year following the implementation of radioprotection strategies, there was a 22% reduction of radiological examinations performed at the pediatric emergency room. There was also a 29% reduction in the request of two or more radiological examinations for the same child or examinations with two or more incidences. The campaign and the radioprotection card for children under 12 years old proved to be feasible strategies and correlated with a reduction in radiological examinations requested and performed at the pediatric emergency room.

Assessing the role of GPs in Nordic health care systems.

Science.gov (United States)

Quaye, Randolph K

2016-05-03

Purpose This paper examines the changing role of general practitioners (GPs) in Nordic countries of Sweden, Norway and Denmark. It aims to explore the "gate keeping" role of GPs in the face of current changes in the health care delivery systems in these countries. Design/methodology/approach Data were collected from existing literature, interviews with GPs, hospital specialists and representatives of Danish regions and Norwegian Medical Association. Findings The paper contends that in all these changes, the position of the GPs in the medical division of labor has been strengthened, and patients now have increased and broadened access to choice. Research limitations/implications Health care cost and high cancer mortality rates have forced Nordic countries of Sweden, Norway and Denmark to rethink their health care systems. Several attempts have been made to reduce health care cost through market reform and by strenghtening the position of GPs. The evidence suggests that in Norway and Denmark, right incentives are in place to achieve this goal. Sweden is not far behind. The paper has limitations of a small sample size and an exclusive focus on GPs. Practical implications Anecdotal evidence suggests that physicians are becoming extremely unhappy. Understanding the changing status of primary care physicians will yield valuable information for assessing the effectiveness of Nordic health care delivery systems. Social implications This study has wider implications of how GPs see their role as potential gatekeepers in the Nordic health care systems. The role of GPs is changing as a result of recent health care reforms. Originality/value This paper contends that in Norway and Denmark, right incentives are in place to strengthen the position of GPs.

Differences between Practice Patterns of Conventional and Naturopathic GPs in Germany.

Science.gov (United States)

Laux, Gunter; Musselmann, Berthold; Kiel, Marion; Szecsenyi, Joachim; Joos, Stefanie

2016-01-01

Limited evidence exists whether practice patterns of general practitioners (GPs) who have additionally completed training in naturopathy are different from those of conventional GPs. We aimed to assess and compare practice patterns of GPs in conventional and naturopathic GPs. Routine data from 41 GPs (31 with and 11 without additional qualification in NP, respectively) and 180,789 patients, drawn from the CONTinuous morbidity registration Epidemiologic NeTwork (CONTENT)-registry and collected between 2009 and 2014, were used. To assess practice patterns determinants of (non-)phytopharmaceutical prescriptions, referrals and hospitalizations were analyzed using mixed-effects Poisson regression models. As explanatory variables, the qualification of the GP in NM, the age group and sex of the patient, as well as bivariate interactions between these variables were considered. GPs additionally qualified in naturopathy exhibited higher rates of phytopharmaceutical prescriptions (pGPs. This association was not observed with respect to non-phytopharmaceutical prescriptions. However, interaction effects between qualification and age group as well as sex were present with respect to both phytopharmaceutical and non-phytopharmaceutical prescriptions (all pGPs could be subject to certain age groups and sex. However, the magnitude of these differences seem to be rather small.

TAGGING, TRACKING AND LOCATING WITHOUT GPS

Energy Technology Data Exchange (ETDEWEB)

Cordaro, J.; Coleman, T.; Shull, D.

2012-07-08

The Savannah River National Laboratory (SRNL) was requested to lead a Law Enforcement Working Group that was formed to collaborate on common operational needs. All agencies represented on the working group ranked their need to tag, track, and locate a witting or unwitting target as their highest priority. Specifically, they were looking for technologies more robust than Global Positioning Satellite (GPS), could communicate back to the owner, and worked where normal cell phone communications did not work or were unreliable. SRNL brought together multiple technologies in a demonstration that was held in in various Alaska venues, including metropolitan, wilderness, and at-sea that met the working group's requirements. Using prototypical technologies from Boeing, On Ramp, and Fortress, SRNL was able to demonstrate the ability to track personnel and material in all scenarios including indoors, in heavily wooden areas, canyons, and in parking garages. In all cases GPS signals were too weak to measure. Bi-directional communication was achieved in areas that Wi-Fi, cell towers, or traditional radios would not perform. The results of the exercise will be presented. These technologies are considered ideal for tracking high value material such has nuclear material with a platform that allows seamless tracking anywhere in the world, indoors or outdoors.

Relationships between GPS-signal propagation errors and EISCAT observations

Directory of Open Access Journals (Sweden)

N. Jakowski

1996-12-01

Full Text Available When travelling through the ionosphere the signals of space-based radio navigation systems such as the Global Positioning System (GPS are subject to modifications in amplitude, phase and polarization. In particular, phase changes due to refraction lead to propagation errors of up to 50 m for single-frequency GPS users. If both the L1 and the L2 frequencies transmitted by the GPS satellites are measured, first-order range error contributions of the ionosphere can be determined and removed by difference methods. The ionospheric contribution is proportional to the total electron content (TEC along the ray path between satellite and receiver. Using about ten European GPS receiving stations of the International GPS Service for Geodynamics (IGS, the TEC over Europe is estimated within the geographic ranges -20°≤ λ ≤40°E and 32.5°≤ Φ ≤70°N in longitude and latitude, respectively. The derived TEC maps over Europe contribute to the study of horizontal coupling and transport proces- ses during significant ionospheric events. Due to their comprehensive information about the high-latitude ionosphere, EISCAT observations may help to study the influence of ionospheric phenomena upon propagation errors in GPS navigation systems. Since there are still some accuracy limiting problems to be solved in TEC determination using GPS, data comparison of TEC with vertical electron density profiles derived from EISCAT observations is valuable to enhance the accuracy of propagation-error estimations. This is evident both for absolute TEC calibration as well as for the conversion of ray-path-related observations to vertical TEC. The combination of EISCAT data and GPS-derived TEC data enables a better understanding of large-scale ionospheric processes.

Significance of likes: Analysing passive interactions on Facebook during campaigning.

Directory of Open Access Journals (Sweden)

Mohammad Adib Khairuddin

Full Text Available With more and more political candidates using social media for campaigning, researchers are looking at measuring the effectiveness of this medium. Most research, however, concentrates on the bare count of likes (or twitter mentions in an attempt to correlate social media presence and winning. In this paper, we propose a novel method, Interaction Strength Plot (IntS to measure the passive interactions between a candidate's posts on Facebook and the users (liking the posts. Using this method on original Malaysian General Election (MGE13 and Australian Federal Elections (AFE13 Facebook Pages (FP campaign data, we label an FP as performing well if both the posting frequency and the likes gathered are above average. Our method shows that over 60% of the MGE13 candidates and 85% of the AFE13 candidates studied in this paper had under-performing FP. Some of these FP owners would have been identified as popular based on bare count. Thus our performance chart is a vital step forward in measuring the effectiveness of online campaigning.

Significance of likes: Analysing passive interactions on Facebook during campaigning.

Science.gov (United States)

Khairuddin, Mohammad Adib; Rao, Asha

2017-01-01

With more and more political candidates using social media for campaigning, researchers are looking at measuring the effectiveness of this medium. Most research, however, concentrates on the bare count of likes (or twitter mentions) in an attempt to correlate social media presence and winning. In this paper, we propose a novel method, Interaction Strength Plot (IntS) to measure the passive interactions between a candidate's posts on Facebook and the users (liking the posts). Using this method on original Malaysian General Election (MGE13) and Australian Federal Elections (AFE13) Facebook Pages (FP) campaign data, we label an FP as performing well if both the posting frequency and the likes gathered are above average. Our method shows that over 60% of the MGE13 candidates and 85% of the AFE13 candidates studied in this paper had under-performing FP. Some of these FP owners would have been identified as popular based on bare count. Thus our performance chart is a vital step forward in measuring the effectiveness of online campaigning.

Crystal growth and scintillation properties of multi-component oxide single crystals: Ce:GGAG and Ce:La-GPS

Energy Technology Data Exchange (ETDEWEB)

Yoshikawa, A., E-mail: yoshikawa@imr.tohoku.ac.jp [Institute for Materials Research (IMR), Tohoku University, Sendai 980-8577 (Japan); New Industry Creation Hatchery Center (NICHe), Tohoku University, Sendai 980-8579 (Japan); C& A Corporation, 6-6-40 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579 (Japan); Kamada, K. [New Industry Creation Hatchery Center (NICHe), Tohoku University, Sendai 980-8579 (Japan); C& A Corporation, 6-6-40 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579 (Japan); Kurosawa, S. [Institute for Materials Research (IMR), Tohoku University, Sendai 980-8577 (Japan); New Industry Creation Hatchery Center (NICHe), Tohoku University, Sendai 980-8579 (Japan); Shoji, Y. [Institute for Materials Research (IMR), Tohoku University, Sendai 980-8577 (Japan); C& A Corporation, 6-6-40 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579 (Japan); Yokota, Y. [New Industry Creation Hatchery Center (NICHe), Tohoku University, Sendai 980-8579 (Japan); Chani, V.I. [Institute for Materials Research (IMR), Tohoku University, Sendai 980-8577 (Japan); Nikl, M. [Institute of Physics, AS CR, Cukrovarnická 10, 162 53 Prague (Czech Republic)

2016-01-15

Crystal growth by micro-pulling-down, Czochralski, and floating zone methods and scintillation properties of Ce:Gd{sub 3}(Ga,Al){sub 5}O{sub 12} (Ce:GGAG) multi-component oxide garnets, and Ce:Gd{sub 2}Si{sub 2}O{sub 7} (Ce:GPS) or Ce:(La,Gd){sub 2}Si{sub 2}O{sub 7} (Ce:La-GPS) pyro-silicates are reviewed. GGAG crystals demonstrated practically linear dependences of some of the parameters including lattice constant, emission wavelength, and band gap on Ga content. However, emission intensity, light yield and energy resolution showed maxima for intermediate compositions. GGAG crystals had the highest light yield of 56,000 photon/MeV for Ga content of 2.7 atoms per garnet formula unit. Similarly the light yield and energy resolution of La-GPS showed the highest values of 40,000 photon/MeV and 4.4%@662 keV, respectively, for La-GPS containing 10% of La. Moreover, La-GPS demonstrated stable scintillation performance up to 200 °C.

The Statistics of GPS

National Research Council Canada - National Science Library

Matsakis, Demetrios

2007-01-01

The Global Positioning System (GPS) is an extremely effective satellite-based system that broadcasts sufficient information for a user to determine time and position from any location on or near the Earth...

GLOBE Aerosol Field Campaign - U.S. Pilot Study 2016

Science.gov (United States)

Pippin, Margaret; Marentette, Christina; Bujosa, Robert; Taylor, Jessica; Lewis, Preston

2016-01-01

During the spring of 2016, from April 4 - May 27, sixteen GLOBE schools participated in the GLOBE Aerosol Field Campaign - U.S. Pilot Study. Thirteen teachers from these schools had previously participated in the NASA LEARN program (Long-term Experience in Authentic Research with NASA) where they were GLOBE trained in Atmosphere protocols, and engaged in 1-3 years of research under the mentorship of NASA scientists. Each school was loaned two aerosol instruments for the Campaign duration, either 2 GLOBE sun photometers, 2 Calitoo sun photometers, or 1 of each. This allowed for students to make measurements side-by-side and in the case of the Calitoos, to compare AOT results immediately with each other for better consistency in data collection. Additionally, as part of the Field Campaign evaluation, multiple instruments allow for an assessment of the ease of use of each instrument for grade level of students, whether in middle school or high school. Before the Campaign, all GLOBE and Calitoo instruments were 'checked out' against an AERONET, then checked again upon return after the Campaign. By examining all data, before, during and after the Campaign, this gives an indication of instrument performance and proficiency obtained by the students. Support was provided to each teacher and their students at the level requested, via email, phone or video conferencing.

GPS sledovací systém

OpenAIRE

Hofman, Jan

2010-01-01

V práci je popsán základní princip a vlastnosti globálního pozičního systému GPS. Je zde přiblížena problematika určování polohy, rychlosti a nadmořské výšky. Tyto poznatky jsou dále použity pro návrh zařízení, které komunikuje s běžně vyráběným GPS přijímačem a z něj získané informace zpracovává a ukládá do paměti pro pozdější vyhodnocení The keystone and properties of Global Position System (GPS) are described in this thesis. The thesis explains questions of position, speed and elevation...

Arctic tides from GPS on sea ice

OpenAIRE

Kildegaard Rose, Stine; Skourup, Henriette; Forsberg, René

2012-01-01

The presence of sea-ice in the Arctic Ocean plays a significant role in the Arctic climate. Sea ice dampens the ocean tide amplitude with the result that global tidal models which use only astronomical data perform less accurately in the polar regions. This study presents a kinematic processing of Global Positioning System (GPS) buoys placed on sea-ice at five different sites north of Greenland for the study of sea level height and tidal analysis to improve tidal models in the Central Arctic....

Soil Moisture Retrieval Based on GPS Signal Strength Attenuation

Directory of Open Access Journals (Sweden)

Franziska Koch

2016-07-01

Full Text Available Soil moisture (SM is a highly relevant variable for agriculture, the emergence of floods and a key variable in the global energy and water cycle. In the last years, several satellite missions have been launched especially to derive large-scale products of the SM dynamics on the Earth. However, in situ validation data are often scarce. We developed a new method to retrieve SM of bare soil from measurements of low-cost GPS (Global Positioning System sensors that receive the freely available GPS L1-band signals. The experimental setup of three GPS sensors was installed at a bare soil field at the German Weather Service (DWD in Munich for almost 1.5 years. Two GPS antennas were installed within the soil column at a depth of 10 cm and one above the soil. SM was successfully retrieved based on GPS signal strength losses through the integral soil volume. The results show high agreement with measured and modelled SM validation data. Due to its non-destructive, cheap and low power setup, GPS sensor networks could also be used for potential applications in remote areas, aiming to serve as satellite validation data and to support the fields of agriculture, water supply, flood forecasting and climate change.

Ionospheric correction for spaceborne single-frequency GPS based ...

Indian Academy of Sciences (India)

A modified ionospheric correction method and the corresponding approximate algorithm for spaceborne single-frequency Global Positioning System (GPS) users are proposed in this study. Single Layer Model (SLM) mapping function for spaceborne GPS was analyzed. SLM mapping functions at different altitudes were ...

Internet Explorers: the online campaign

NARCIS (Netherlands)

Wall, M.; Sudulich, M.L.; Gallagher, M.; Marsh, M.

2011-01-01

The idea of an ‘internet election’ was initially put forward in 1997. However, there is little evidence to date that online campaigning has supplanted more traditional campaign practices. This is particularly true of Irish campaigns, which are hardware-rich affairs characterised by substantial

Comparação de três receptores GPS para uso em agricultura de precisão Comparison of three GPS receiver for precision agriculture uses

Directory of Open Access Journals (Sweden)

Marcelo C. C. Stabile

2006-04-01

date and time of data collection were chosen to minimize the physical dilution of precision (PDOP. The three receivers had quite different performance. The GPS "A" (8-channel had the highest variability and the lowest repeatability of data. The differential GPS (DGPS "B" (12-channel had higher accuracy, with a maximum deviation of 6m, but with significant repeatability. The GPS "C" with optimized algorithm had the highest accuracy and deviations no greater than 2m. Both GPS's "B" and "C" are adequate for Precision Agriculture uses.

Global Ionospheric Modelling using Multi-GNSS: BeiDou, Galileo, GLONASS and GPS.

Science.gov (United States)

Ren, Xiaodong; Zhang, Xiaohong; Xie, Weiliang; Zhang, Keke; Yuan, Yongqiang; Li, Xingxing

2016-09-15

The emergence of China's Beidou, Europe's Galileo and Russia's GLONASS satellites has multiplied the number of ionospheric piercing points (IPP) offered by GPS alone. This provides great opportunities for deriving precise global ionospheric maps (GIMs) with high resolution to improve positioning accuracy and ionospheric monitoring capabilities. In this paper, the GIM is developed based on multi-GNSS (GPS, GLONASS, BeiDou and Galileo) observations in the current multi-constellation condition. The performance and contribution of multi-GNSS for ionospheric modelling are carefully analysed and evaluated. Multi-GNSS observations of over 300 stations from the Multi-GNSS Experiment (MGEX) and International GNSS Service (IGS) networks for two months are processed. The results show that the multi-GNSS GIM products are better than those of GIM products based on GPS-only. Differential code biases (DCB) are by-products of the multi-GNSS ionosphere modelling, the corresponding standard deviations (STDs) are 0.06 ns, 0.10 ns, 0.18 ns and 0.15 ns for GPS, GLONASS, BeiDou and Galileo, respectively in satellite, and the STDs for the receiver are approximately 0.2~0.4 ns. The single-frequency precise point positioning (SF-PPP) results indicate that the ionospheric modelling accuracy of the proposed method based on multi-GNSS observations is better than that of the current dual-system GIM in specific areas.

Validity and reliability of GPS and LPS for measuring distances covered and sprint mechanical properties in team sports.

Science.gov (United States)

Hoppe, Matthias W; Baumgart, Christian; Polglaze, Ted; Freiwald, Jürgen

2018-01-01

This study aimed to investigate the validity and reliability of global (GPS) and local (LPS) positioning systems for measuring distances covered and sprint mechanical properties in team sports. Here, we evaluated two recently released 18 Hz GPS and 20 Hz LPS technologies together with one established 10 Hz GPS technology. Six male athletes (age: 27±2 years; VO2max: 48.8±4.7 ml/min/kg) performed outdoors on 10 trials of a team sport-specific circuit that was equipped with double-light timing gates. The circuit included various walking, jogging, and sprinting sections that were performed either in straight-lines or with changes of direction. During the circuit, athletes wore two devices of each positioning system. From the reported and filtered velocity data, the distances covered and sprint mechanical properties (i.e., the theoretical maximal horizontal velocity, force, and power output) were computed. The sprint mechanical properties were modeled via an inverse dynamic approach applied to the center of mass. The validity was determined by comparing the measured and criterion data via the typical error of estimate (TEE), whereas the reliability was examined by comparing the two devices of each technology (i.e., the between-device reliability) via the coefficient of variation (CV). Outliers due to measurement errors were statistically identified and excluded from validity and reliability analyses. The 18 Hz GPS showed better validity and reliability for determining the distances covered (TEE: 1.6-8.0%; CV: 1.1-5.1%) and sprint mechanical properties (TEE: 4.5-14.3%; CV: 3.1-7.5%) than the 10 Hz GPS (TEE: 3.0-12.9%; CV: 2.5-13.0% and TEE: 4.1-23.1%; CV: 3.3-20.0%). However, the 20 Hz LPS demonstrated superior validity and reliability overall (TEE: 1.0-6.0%; CV: 0.7-5.0% and TEE: 2.1-9.2%; CV: 1.6-7.3%). For the 10 Hz GPS, 18 Hz GPS, and 20 Hz LPS, the relative loss of data sets due to measurement errors was 10.0%, 20.0%, and 15.8%, respectively. This study shows that

Accuracy of velocities from repeated GPS surveys: relative positioning is concerned

Science.gov (United States)

Duman, Huseyin; Ugur Sanli, D.

2016-04-01

Over more than a decade, researchers have been interested in studying the accuracy of GPS positioning solutions. Recently, reporting the accuracy of GPS velocities has been added to this. Researchers studying landslide motion, tectonic motion, uplift, sea level rise, and subsidence still report results from GPS experiments in which repeated GPS measurements from short sessions are used. This motivated some other researchers to study the accuracy of GPS deformation rates/velocities from various repeated GPS surveys. In one of the efforts, the velocity accuracy was derived from repeated GPS static surveys using short observation sessions and Precise Point Positioning mode of GPS software. Velocities from short GPS sessions were compared with the velocities from 24 h sessions. The accuracy of velocities was obtained using statistical hypothesis testing and quantifying the accuracy of least squares estimation models. The results reveal that 45-60 % of the horizontal and none of the vertical solutions comply with the results from 24 h solutions. We argue that this case in which the data was evaluated using PPP should also apply to the case in which the data belonging to long GPS base lengths is processed using fundamental relative point positioning. To test this idea we chose the two IGS stations ANKR and NICO and derive their velocities from the reference stations held fixed in the stable EURASIAN plate. The University of Bern's GNSS software BERNESE was used to produce relative positioning solutions, and the results are compared with those of GIPSY/OASIS II PPP results. First impressions indicate that it is worth designing a global experiment and test these ideas in detail.

Intercomparison of aerosol measurements performed with multi-wavelength Raman lidars, automatic lidars and ceilometers in the framework of INTERACT-II campaign

Science.gov (United States)

Madonna, Fabio; Rosoldi, Marco; Lolli, Simone; Amato, Francesco; Vande Hey, Joshua; Dhillon, Ranvir; Zheng, Yunhui; Brettle, Mike; Pappalardo, Gelsomina

2018-04-01

Following the previous efforts of INTERACT (INTERcomparison of Aerosol and Cloud Tracking), the INTERACT-II campaign used multi-wavelength Raman lidar measurements to assess the performance of an automatic compact micro-pulse lidar (MiniMPL) and two ceilometers (CL51 and CS135) in providing reliable information about optical and geometric atmospheric aerosol properties. The campaign took place at the CNR-IMAA Atmospheric Observatory (760 m a. s. l. ; 40.60° N, 15.72° E) in the framework of ACTRIS-2 (Aerosol Clouds Trace gases Research InfraStructure) H2020 project. Co-located simultaneous measurements involving a MiniMPL, two ceilometers and two EARLINET multi-wavelength Raman lidars were performed from July to December 2016. The intercomparison highlighted that the MiniMPL range-corrected signals (RCSs) show, on average, a fractional difference with respect to those of CNR-IMAA Atmospheric Observatory (CIAO) lidars ranging from 5 to 15 % below 2.0 km a.s.l. (above sea level), largely due to the use of an inaccurate overlap correction, and smaller than 5 % in the free troposphere. For the CL51, the attenuated backscatter values have an average fractional difference with respect to CIAO lidars performance is similar to the CL51 below 2.0 km a. s. l. , while in the region above 3 km a. s. l. the differences are about ±40 %. The variability of the CS135 normalization constant is within ±47 %.Finally, additional tests performed during the campaign using the CHM15k ceilometer operated at CIAO showed the clear need to investigate the CHM15k historical dataset (2010-2016) to evaluate potential effects of ceilometer laser fluctuations on calibration stability. The number of laser pulses shows an average variability of 10 % with respect to the nominal power which conforms to the ceilometer specifications. Nevertheless, laser pulses variability follows seasonal behavior with an increase in the number of laser pulses in summer and a decrease in winter. This contributes to

Long-term effects of a climate change teaching campaign – a case study

DEFF Research Database (Denmark)

Cruys-Bagger, Søren Ib; Daugbjerg, Peer

The authors perform in association with School of Education, Aarhus University an evaluation of the long term effects of the campaign visit. We are investigating the sustainable effect of science campaigns for schools by collecting teachers reflection on the value of the visit of “Klimakaravanen”...... of doing experiments c) Relations to technological companies and the civil society d) Skills of planning, performing and evaluating teaching...

Identification of slip surface location by TLS-GPS datafor landslide mitigation case study: Ciloto-Puncak, West Java

Energy Technology Data Exchange (ETDEWEB)

Sadarviana, Vera, E-mail: vsadarviana@gmail.com; Hasanuddin, A. Z.; Joenil, G. K.; Irwan; Wijaya, Dudy; Ilman, H.; Agung, N.; Achmad, R. T.; Pangeran, C.; Martin, S.; Gamal, M. [Geodesy Research Group, Faculty of Earth Sciences and Technology, Bandung Institute of Technology, Jl. Ganesha 10, Bandung 40132, West Java (Indonesia); Santoso, Djoko [Geophysics Engineering Research Group, Faculty of Geoscience and Mineral Engineering, Bandung Institute of Technology, Jl. Ganesha 10, Bandung 40132, West Java (Indonesia)

2015-04-24

Landslide can prevented by understanding the direction of movement to the safety evacuation track or slip surface location to hold avalanches. Slip surface is separating between stable soil and unstable soil in the slope. The slip surface location gives information about stable material depth. The information can be utilize to mitigate technical step, such as pile installation to keep construction or settlement safe from avalanches.There are two kinds landslide indicators which are visualization and calculation. By visualization, landslide identified from soil crack or scarp. Scarp is a scar of exposed soil on the landslide. That identification can be done by Terrestrial Laser Scanner (TLS) Image. Shape of scarp shows type of slip surface, translation or rotational. By calculation, kinematic and dynamic mathematic model will give vector, velocity and acceleration of material movement. In this calculation need velocity trend line at GPS point from five GPS data campaign. From intersection of trend lines it will create curves or lines of slip surface location. The number of slip surface can be known from material movement direction in landslide zone.Ciloto landslide zone have complicated phenomenon because that zone have influence from many direction of ground water level pressure. The pressure is causes generating several slip surface in Ciloto zone. Types of Ciloto slip surface have mix between translational and rotational type.

Identification of slip surface location by TLS-GPS datafor landslide mitigation case study: Ciloto-Puncak, West Java

International Nuclear Information System (INIS)

Sadarviana, Vera; Hasanuddin, A. Z.; Joenil, G. K.; Irwan; Wijaya, Dudy; Ilman, H.; Agung, N.; Achmad, R. T.; Pangeran, C.; Martin, S.; Gamal, M.; Santoso, Djoko

2015-01-01

Landslide can prevented by understanding the direction of movement to the safety evacuation track or slip surface location to hold avalanches. Slip surface is separating between stable soil and unstable soil in the slope. The slip surface location gives information about stable material depth. The information can be utilize to mitigate technical step, such as pile installation to keep construction or settlement safe from avalanches.There are two kinds landslide indicators which are visualization and calculation. By visualization, landslide identified from soil crack or scarp. Scarp is a scar of exposed soil on the landslide. That identification can be done by Terrestrial Laser Scanner (TLS) Image. Shape of scarp shows type of slip surface, translation or rotational. By calculation, kinematic and dynamic mathematic model will give vector, velocity and acceleration of material movement. In this calculation need velocity trend line at GPS point from five GPS data campaign. From intersection of trend lines it will create curves or lines of slip surface location. The number of slip surface can be known from material movement direction in landslide zone.Ciloto landslide zone have complicated phenomenon because that zone have influence from many direction of ground water level pressure. The pressure is causes generating several slip surface in Ciloto zone. Types of Ciloto slip surface have mix between translational and rotational type

GPS system simulation methodology

Science.gov (United States)

Ewing, Thomas F.

1993-01-01

The following topics are presented: background; Global Positioning System (GPS) methodology overview; the graphical user interface (GUI); current models; application to space nuclear power/propulsion; and interfacing requirements. The discussion is presented in vugraph form.

Briefing Highlights Vulnerability of GPS to Adverse Space Weather

Science.gov (United States)

Balcerak, Ernie

2011-08-01

Through its effects on GPS and other technologies, space weather can affect a variety of industries, including agriculture, commercial air travel, and emergency response. Speakers focused on these topics at a 22 June briefing on Capitol Hill in Washington, D. C. Solar flares can produce radio bursts that directly interfere with GPS signals. Solar activity can also cause ionospheric disturbances that produce distortions and delays in GPS signals, degrading the accuracy of positioning and navigation systems.

GeoTravel: Harvesting Ambient Geographic Footprints from GPS Trajectories

OpenAIRE

Liew, Li Ching; Goh, Ong Sing

2014-01-01

This study is about harvesting point of interest from GPS trajectories. Trajectories are the paths that moving objects move by follow through space in a function of time while GPS trajectories generally are point-sequences with geographic coordinates, time stamp, speed and heading. User can get information from GPS enable device. For example, user can acquire present location, search the information around them and design driving routes to a destination and thus design travel itineraries. By ...

Greenland ice mass balance from GPS, GRACE and ICESat

DEFF Research Database (Denmark)

Khan, Shfaqat Abbas; Kjær, Kurt H.; Korsgaard, Niels Jákup

Greenland, using stereoscopic coverage by aerial photographs recorded in 1985, and subsequent comparative surface elevation data from ICESat (Ice, Cloud and land Elevation Satellite) and ATM (Airborne Topographic Mapper) supplemented with measurements from GPS and the Gravity Recovery and Climate Experiment...... (GRACE) satellite gravity mission, launched in March, 2002. The GRACE results provide a direct measure of mass loss, while the GPS data are used to monitor crustal uplift caused by ice mass loss close to the GPS sites....

GPS/MEMS IMU/Microprocessor Board for Navigation

Science.gov (United States)

Gender, Thomas K.; Chow, James; Ott, William E.

2009-01-01

A miniaturized instrumentation package comprising a (1) Global Positioning System (GPS) receiver, (2) an inertial measurement unit (IMU) consisting largely of surface-micromachined sensors of the microelectromechanical systems (MEMS) type, and (3) a microprocessor, all residing on a single circuit board, is part of the navigation system of a compact robotic spacecraft intended to be released from a larger spacecraft [e.g., the International Space Station (ISS)] for exterior visual inspection of the larger spacecraft. Variants of the package may also be useful in terrestrial collision-detection and -avoidance applications. The navigation solution obtained by integrating the IMU outputs is fed back to a correlator in the GPS receiver to aid in tracking GPS signals. The raw GPS and IMU data are blended in a Kalman filter to obtain an optimal navigation solution, which can be supplemented by range and velocity data obtained by use of (l) a stereoscopic pair of electronic cameras aboard the robotic spacecraft and/or (2) a laser dynamic range imager aboard the ISS. The novelty of the package lies mostly in those aspects of the design of the MEMS IMU that pertain to controlling mechanical resonances and stabilizing scale factors and biases.

Crustal deformations at permanent GPS sites in Denmark

DEFF Research Database (Denmark)

Khan, Shfaqat Abbas; Knudsen, Per; Tscherning, Carl Christian

2005-01-01

The National Survey and Cadastre (KMS) is responsible for the geodetic definition of the reference network in Denmark. Permanent GPS stations play an important role in the monitoring and maintenance of the geodetic network. During 1998 and 1999 KMS established three permanent GPS station in Denma...

5 CFR 950.801 - Campaign schedule.

Science.gov (United States)

2010-01-01

... 5 Administrative Personnel 2 2010-01-01 2010-01-01 false Campaign schedule. 950.801 Section 950... VOLUNTARY ORGANIZATIONS CFC Timetable § 950.801 Campaign schedule. (a) The Combined Federal Campaign will be.../International and International parts of the Charity List to all local campaigns by a date to be determined by...

[Evaluation of national prevention campaigns against AIDS: analysis model].

Science.gov (United States)

Hausser, D; Lehmann, P; Dubois, F; Gutzwiller, F

1987-01-01

The evaluation of the "Stop-Aids" campaign is based upon a model of behaviour modification (McAlister) which includes the communication theory of McGuire and the social learning theory of Bandura. Using this model, it is possible to define key variables that are used to measure the impact of the campaign. Process evaluation allows identification of multipliers that reinforce and confirm the initial message of prevention (source) thereby encouraging behaviour modifications that are likely to reduce the transmission of HIV (condom use, no sharing of injection material, monogamous relationship, etc.). Twelve studies performed by seven teams in the three linguistic areas contribute to the project. A synthesis of these results will be performed by the IUMSP.

GPS Technology and Human Psychological Research: A Methodological Proposal

Directory of Open Access Journals (Sweden)

Pedro S. A. Wolf

2010-10-01

Full Text Available Animal behaviorists have made extensive use of GPS technology since 1991. In contrast, psychological research has made little use of the technology, even though the technology is relatively inexpensive, familiar, and widespread. Hence, its potential for pure and applied psychological research remains untapped. We describe three methods psychologists could apply to individual differences research, clinical research, or spatial use research. In the context of individual differences research, GPS technology permits us to test hypotheses predicting specific relations among patterns of spatial use and individual differences variables. In a clinical context, GPS technology provides outcome measures that may relate to the outcome of interventions designed to treat psychological disorders that, for example, may leave a person homebound (e.g. Agoraphobia, PTSD, TBI. Finally, GPS technology provides natural measures of spatial use. We, for example, used GPS technology to quantify traffic flow and exhibit use at the Arizona Sonora Desert Museum. Interested parties could easily extend this methodology some aspects of urban planning or business usage.DOI: 10.2458/azu_jmmss.v1i1.74

IceBridge GPS L0 Raw Satellite Navigation Data

Data.gov (United States)

National Aeronautics and Space Administration — The NASA IceBridge GPS L0 Raw Satellite Navigation Data (IPUTG0) data set contains GPS readings, including latitude, longitude, track, ground speed, off distance,...

ULF fluctuations of the geomagnetic field and ionospheric sounding measurements at low latitudes during the first CAWSES campaign

Directory of Open Access Journals (Sweden)

U. Villante

2006-07-01

Full Text Available We present an analysis of ULF geomagnetic field fluctuations at low latitudes during the first CAWSES campaign (29 March-3 April 2004. During the whole campaign, mainly in the prenoon sector, a moderate Pc3-4 pulsation activity is observed, clearly related to interplanetary upstream waves. On 3 April, in correspondence to the Earth's arrival of a coronal mass ejection, two SIs are observed whose waveforms are indicative of a contribution of the high-latitude ionospheric currents to the low-latitude ground field. During the following geomagnetic storm, low frequency (Pc5 waves are observed at discrete frequencies. Their correspondence with the same frequencies detected in the radial components of the interplanetary magnetic field and solar wind speed suggests that Alfvénic solar wind fluctuations may act as direct drivers of magnetospheric fluctuations. A cross-phase analysis, using different pairs of stations, is also presented for identifying field line resonant frequencies and monitoring changes in plasmaspheric mass density. Lastly, an analysis of ionospheric vertical soundings, measured at the Rome ionosonde station (41.8° N, 12.5° E, and vertical TEC measurements deduced from GPS signals within an European network shows the relation between the ULF resonances in the inner magnetosphere and thermal plasma density variations during geomagnetically quiet conditions, in contrast to various storm phases at the end of the CAWSES campaign.

Physical applications of GPS geodesy: a review.

Science.gov (United States)

Bock, Yehuda; Melgar, Diego

2016-10-01

Geodesy, the oldest science, has become an important discipline in the geosciences, in large part by enhancing Global Positioning System (GPS) capabilities over the last 35 years well beyond the satellite constellation's original design. The ability of GPS geodesy to estimate 3D positions with millimeter-level precision with respect to a global terrestrial reference frame has contributed to significant advances in geophysics, seismology, atmospheric science, hydrology, and natural hazard science. Monitoring the changes in the positions or trajectories of GPS instruments on the Earth's land and water surfaces, in the atmosphere, or in space, is important for both theory and applications, from an improved understanding of tectonic and magmatic processes to developing systems for mitigating the impact of natural hazards on society and the environment. Besides accurate positioning, all disturbances in the propagation of the transmitted GPS radio signals from satellite to receiver are mined for information, from troposphere and ionosphere delays for weather, climate, and natural hazard applications, to disturbances in the signals due to multipath reflections from the solid ground, water, and ice for environmental applications. We review the relevant concepts of geodetic theory, data analysis, and physical modeling for a myriad of processes at multiple spatial and temporal scales, and discuss the extensive global infrastructure that has been built to support GPS geodesy consisting of thousands of continuously operating stations. We also discuss the integration of heterogeneous and complementary data sets from geodesy, seismology, and geology, focusing on crustal deformation applications and early warning systems for natural hazards.

SLR and GPS spatial techniques in ITRF. Argentine results.

Science.gov (United States)

Actis, Eloy Vicente; Huang, Dongping; Márquez, Raúl; Adarvez, Sonia; Flores, Matías; Brizuela, Diego; Nievas, Jesica; Podestá, Ricardo; Pacheco, Ana M.; Rojas, Hernán Alvis; Yin, Zhiqiang; Li, Jinzeng; Han, Yanben; Liu, Weidong; Wang, Rui

2012-08-01

Along the late 30 years spatial geodetic techniques enable us to measure horizontal and vertical deformations of the Earth’s surface with a very high precision. Performing this task we made Satellite Laser Ranging (SLR), and Global Positioning System (GPS) observations in South America ILRS 7406 Station placed at Observatorio Astronómico Félix Aguilar (OAFA) in San Juan, Argentina, accomplishing a Cooperation Agreement between CAS - NAOC and OAFA - UNSJ. Trough LAGEOS II Satellite observations we obtain rectangular coordinates of San Juan ILRS Station in the Terrestrial Reference Frame (ITR 2000), standing out that Argentine Station data were included in the late arrangements ITRF given by International Earth Rotation and Reference System Service (IERS). Spatial and temporary variations of the epoch 2010 - 2011 were evaluated finding out remarkable displacements, of about a half meter, related with seismic events on the region. We confirm these deformations by means of GP S determinations referred to Permanent GPS Station placed nearby the SLR Station.

Kinematic GPS survey as validation of LIDAR strips accuracy

Directory of Open Access Journals (Sweden)

C. Gordini

2006-06-01

Full Text Available As a result of the catastrophic hydrogeological events which occurred in May 1998 in Campania, in the south of Italy, the distinctive features of airborne laser scanning mounted on a helicopter were used to survey the landslides at Sarno and Quindici. In order to survey the entire zone of interest, approximately 21 km2, it was necessary to scan 12 laser strips. Many problems arose during the survey: difficulties in receiving the GPS signal, complex terrain features and unfavorable atmospheric conditions. These problems were investigated and it emerged that one of the most influential factors is the quality of GPS signals. By analysing the original GPS data, the traces obtained by fixing phase ambiguity with an On The Fly (OTF algorithm were isolated from those with smoothed differential GPS solution (DGPS. Processing and analysis of laser data showed that not all the overlapping laser strips were congruent with each other. Since an external survey to verify the laser data accuracy was necessary, it was decided to utilize the kinematic GPS technique. The laser strips were subsequently adjusted, using the kinematic GPS data as reference points. Bearing in mind that in mountainous areas like the one studied here it is not possible to obtain nominal precision and accuracy, a good result was nevertheless obtained with a Digital Terrain Model (DTM of all the zones of interest.

GPS-MBA: computational analysis of MHC class II epitopes in type 1 diabetes.

Science.gov (United States)

Cai, Ruikun; Liu, Zexian; Ren, Jian; Ma, Chuang; Gao, Tianshun; Zhou, Yanhong; Yang, Qing; Xue, Yu

2012-01-01

As a severe chronic metabolic disease and autoimmune disorder, type 1 diabetes (T1D) affects millions of people world-wide. Recent advances in antigen-based immunotherapy have provided a great opportunity for further treating T1D with a high degree of selectivity. It is reported that MHC class II I-A(g7) in the non-obese diabetic (NOD) mouse and human HLA-DQ8 are strongly linked to susceptibility to T1D. Thus, the identification of new I-A(g7) and HLA-DQ8 epitopes would be of great help to further experimental and biomedical manipulation efforts. In this study, a novel GPS-MBA (MHC Binding Analyzer) software package was developed for the prediction of I-A(g7) and HLA-DQ8 epitopes. Using experimentally identified epitopes as the training data sets, a previously developed GPS (Group-based Prediction System) algorithm was adopted and improved. By extensive evaluation and comparison, the GPS-MBA performance was found to be much better than other tools of this type. With this powerful tool, we predicted a number of potentially new I-A(g7) and HLA-DQ8 epitopes. Furthermore, we designed a T1D epitope database (TEDB) for all of the experimentally identified and predicted T1D-associated epitopes. Taken together, this computational prediction result and analysis provides a starting point for further experimental considerations, and GPS-MBA is demonstrated to be a useful tool for generating starting information for experimentalists. The GPS-MBA is freely accessible for academic researchers at: http://mba.biocuckoo.org.

The "Know Stroke" Campaign

Science.gov (United States)

... Issue Past Issues Special Section The "Know Stroke" Campaign Past Issues / Summer 2007 Table of Contents For ... Javascript on. NINDS is conducting a public awareness campaign across the United States to educate people about ...

Seasonal and circadian biases in bird tracking with solar GPS-tags

OpenAIRE

Silva, Rafa; Afán, Isabel; Gil, Juan A.; Bustamante, Javier

2017-01-01

Global Positioning System (GPS) tags are nowadays widely used in wildlife tracking. This geolocation technique can suffer from fix loss biases due to poor satellite GPS geometry, that result in tracking data gaps leading to wrong research conclusions. In addition, new solar-powered GPS tags deployed on birds can suffer from a new "battery drain bias" currently ignored in movement ecology analyses. We use a GPS tracking dataset of bearded vultures (Gypaetus barbatus), tracked for several years...