The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Randolph H Ware - One of the best experts on this subject based on the ideXlab platform.
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GPS meteorology: Remote sensing of atmospheric water vapor using the Global Positioning System
Journal of Geophysical Research: Atmospheres, 1992Co-Authors: Michael Bevis, Christian Rocken, Richard A. Anthes, Steven Businger, Thomas A. Herring, Randolph H WareAbstract:We present a new approach to remote sensing of water vapor based on the Global Positioning System (GPS). Geodesists and geophysicists have devised methods for estimating the extent to which signals propagating from GPS satellites to ground-based GPS receivers are delayed by atmospheric water vapor. This delay is parameterized in terms of a time-varying zenith wet delay (ZWD) which is retrieved by stochastic filtering of the GPS data. Given surface temperature and pressure readings at the GPS receiver, the retrieved ZWD can be transformed with very little additional uncertainty into an estimate of the integrated water vapor (IWV) overlying that receiver. Networks of continuously operating GPS receivers are being constructed by geodesists, geophysicists, government and military agencies, and others in order to implement a wide range of Positioning capabilities. These emerging GPS networks offer the possibility of observing the horizontal distribution of IWV or, equivalently, precipitable water with unprecedented coverage and a temporal resolution of the order of 10 min. These measurements could be utilized in operational weather forecasting and in fundamental research into atmospheric storm Systems, the hydrologic cycle, atmospheric chemistry, and Global climate change. Specially designed, dense GPS networks could be used to sense the vertical distribution of water vapor in their immediate vicinity. Data from ground-based GPS networks could be analyzed in concert with observations of GPS satellite occultations by GPS receivers in low Earth orbit to characterize the atmosphere at planetary scale.
Jean Wolf - One of the best experts on this subject based on the ideXlab platform.
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Global Positioning System assisted prompted recall household travel survey to support development of advanced travel model in jerusalem israel
Transportation Research Record, 2011Co-Authors: Marcelo Oliveira, Jean Wolf, Peter Vovsha, Yehoshua Birotker, Danny Givon, Julie PaascheAbstract:The paper describes recent experience with the application of an innovative Global Positioning System (GPS)-assisted prompted recall (PR) method for a large-scale household travel survey (HTS) in Jerusalem, Israel. The survey was designed to support development of an advanced activity-based model (ABM). The requirements for an HTS to support an advanced ABM are discussed, and the corresponding decisions for survey methods are substantiated. Development of an advanced ABM requires individual records for the entire daily pattern without gaps, missing trips, overlaps, or other data inconsistencies found in a conventional HTS. A consistent record of joint activities and trips of multiple household members is essential. In addition, high levels of spatial and temporal resolution are required. The GPS-assisted PR survey has been identified as the most promising methodology for meeting these requirements. The experience of the first phase of the Jerusalem HTS in 2010 proved the feasibility of the GPS-PR method f...
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accuracy of Global Positioning System for determining driver performance parameters
Transportation Research Record, 2002Co-Authors: Jennifer Ogle, Randall Guensler, William Bachman, Maxim Koutsak, Jean WolfAbstract:Global Positioning System (GPS) technology can continuously monitor the time and location of vehicle usage. By recording and analyzing detailed vehicle activity data, researchers can analyze the safety and environmental implications of driver behavior and trip-making patterns. In 2000, NHTSA awarded the Georgia Institute of Technology a contract to equip 1,100 vehicles with a GPS-enhanced device to collect speed and location data. The objective was to acquire more accurate information on the role of excessive speed on crash frequency and severity. GPS technology allows the researcher to continuously measure driver speed, acceleration, and location. When merged with roadway characteristics within a geographic information System (GIS) environment, determinations of driver risk-taking behavior can be made. Second, continuous logging of GPS data allows researchers to capture high-resolution vehicle activity immediately before a crash event, reducing the potential error and bias introduced during determination...
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elimination of the travel diary experiment to derive trip purpose from Global Positioning System travel data
Transportation Research Record, 2001Co-Authors: Jean Wolf, Randall Guensler, William BachmanAbstract:Several recent pilot studies combined Global Positioning System (GPS) technology with travel survey data collection to evaluate opportunities for improving the quantity and accuracy of travel data. These studies used GPS to supplement traditional data elements collected in paper or electronic travel diaries. Although many traditional trip elements can be obtained from the GPS data, trip purpose has remained an important element, requiring the use of a diary to continue. Presented are the results of a proof-of-concept study conducted at the Georgia Institute of Technology that examined the feasibility of using GPS data loggers to completely replace, rather than supplement, traditional travel diaries. In this approach, all GPS data collected must be processed so that all essential trip data elements, including trip purpose, are derived. If this processing is done correctly and quickly, then the computer-assisted telephone interview retrieval call could be shortened significantly, reducing both respondent bu...
Michael Bevis - One of the best experts on this subject based on the ideXlab platform.
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instantaneous geodetic Positioning at medium distances with the Global Positioning System
Journal of Geophysical Research, 2000Co-Authors: Yehuda Bock, Rosanne M Nikolaidis, Paul J De Jonge, Michael BevisAbstract:We evaluate a new method of Global Positioning System (GPS) data analysis, called instantaneous Positioning, at spatial scale lengths typical of interstation spacings in a modern crustal motion network. This method is more precise and versatile than traditional GPS static and kinematic processing of multi-epoch batches of data. The key to instantaneous Positioning is the ability to resolve integer-cycle phase ambiguities with only a single epoch of dual-frequency phase and pseudorange data, rendering receiver cycle slips irrelevant. We estimate three-dimensional relative coordinates and atmospheric zenith delay parameters independently every 30 s over a 12-week period for baseline distances of 50 m, 14 km, and 37 km. Horizontal precision of a single-epoch coordinate solution is about 15 mm and vertical precision is about 7–8 times worse. Removing that component of each time series which repeats with a period of exactly 1 sidereal day, and thus manifests signal multipath, reduces the scatter by about 50% in all components. Solution averaging of the high-frequency time series can be performed using any number of measurement epochs to further improve coordinate precision. We demonstrate that the daily coordinates estimated with instantaneous Positioning are more precise (by 20–50% per coordinate component) than those estimated with 24-hour batch processing. Spectral analysis of the single-epoch solutions indicates that the flicker noise characteristic of GPS time series observed in lower-frequency bands also affects GPS solutions in the frequency band 0.01 mHz to 10 mHz. We argue that the flicker noise is induced by tropospheric effects. Since modern GPS receivers are capable of observing at frequencies as high as 10 Hz, our technique significantly overlaps and complements the frequency band of broadband seismology and benefits other research areas such as earthquake geodesy, volcanology, and GPS meteorology.
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GPS meteorology: Remote sensing of atmospheric water vapor using the Global Positioning System
Journal of Geophysical Research: Atmospheres, 1992Co-Authors: Michael Bevis, Christian Rocken, Richard A. Anthes, Steven Businger, Thomas A. Herring, Randolph H WareAbstract:We present a new approach to remote sensing of water vapor based on the Global Positioning System (GPS). Geodesists and geophysicists have devised methods for estimating the extent to which signals propagating from GPS satellites to ground-based GPS receivers are delayed by atmospheric water vapor. This delay is parameterized in terms of a time-varying zenith wet delay (ZWD) which is retrieved by stochastic filtering of the GPS data. Given surface temperature and pressure readings at the GPS receiver, the retrieved ZWD can be transformed with very little additional uncertainty into an estimate of the integrated water vapor (IWV) overlying that receiver. Networks of continuously operating GPS receivers are being constructed by geodesists, geophysicists, government and military agencies, and others in order to implement a wide range of Positioning capabilities. These emerging GPS networks offer the possibility of observing the horizontal distribution of IWV or, equivalently, precipitable water with unprecedented coverage and a temporal resolution of the order of 10 min. These measurements could be utilized in operational weather forecasting and in fundamental research into atmospheric storm Systems, the hydrologic cycle, atmospheric chemistry, and Global climate change. Specially designed, dense GPS networks could be used to sense the vertical distribution of water vapor in their immediate vicinity. Data from ground-based GPS networks could be analyzed in concert with observations of GPS satellite occultations by GPS receivers in low Earth orbit to characterize the atmosphere at planetary scale.
Putra, Tri Dharma - One of the best experts on this subject based on the ideXlab platform.
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Metode Location Based Service Dalam Mengurangi Resiko Tersesat Saat Pendakian Gunung Menggunakan Global Positioning System (GPS)
'Universitas Bhayangkara Jakarta Raya', 2020Co-Authors: Nugroho, Danan Rifandi, Ramdhani Asep, Putra, Tri DharmaAbstract:Abstract Climbing in Indonesia from year to year has increased the demand. More and more climbers are interested in this activity but increasingly also accidents that occur in the mountain due to lack of knowledge and discipline of climbers. The mountaineering guide app is made to help climbers to plan preparations before climbing and while climbing the mountains, this app also features a mountain position layout and path from basecamp, climbing posts to the top, and can request evacuation requests at TimSAR. By using the technology of Global Positioning System and Location Based Service climbers can easily find the point where it is located, and can minimize accidents and even death that can occur in the mountain. Keywords: Mountaineer, Location Based Service, Global Positioning System, Mountain Climbing Guide. Abstrak Pendakian di Indonesia dari tahun ke tahun mengalami peningkatan peminatnya. Semakin banyak pendaki yang meminati kegiatan ini tetapi semakin bertambah pula kecelakaan yang terjadi di gunung akibat kurangnya pengetahuan dan kedisiplinan pendaki. Aplikasi panduan mendaki gunung dibuat untuk membantu para pendaki untuk merencanakan persiapan sebelum mendaki dan saat mendaki gunung, aplikasi ini juga dilengkapi dengan tata letak posisi gunung dan jalur dari basecamp, pos-pos pendakian sampai ke puncak, dan dapat meminta permintaan evakuasi pada TimSAR. Dengan menggunakan teknologi Global Positioning System dan Location Based Service pendaki dapat dengan mudah mencari titik posisinya berada, dan dapat meminimalisir kecelakaan bahkan kematian yang dapat terjadi di gunung. Kata kunci: Pendaki Gunung, Location Based Service, Global Positioning System, Panduan Mendaki Gunung.
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Metode Location Based Service Dalam Mengurangi Resiko Tersesat Saat Pendakian Gunung Menggunakan Global Positioning System (GPS)
Journal of Information and Information Security (JIFORTY) Universitas Bhayangkara Jaya, 2020Co-Authors: Putra, Tri DharmaAbstract:Climbing in Indonesia from year to year has increased the demand. More and more climbers are interested in this activity but increasingly also accidents that occur in the mountain due to lack of knowledge and discipline of climbers. The mountaineering guide app is made to help climbers to plan preparations before climbing and while climbing the mountains, this app also features a mountain position layout and path from basecamp, climbing posts to the top, and can request evacuation requests at TimSAR. By using the technology of Global Positioning System and Location Based Service climbers can easily find the point where it is located, and can minimize accidents and even death that can occur in the mountain. Keywords: Mountaineer, Location Based Service, Global Positioning System, Mountain Climbing Guide
Rocco Zito - One of the best experts on this subject based on the ideXlab platform.
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integration of the Global Positioning System and geographical information Systems for traffic congestion studies
Transportation Research Part C-emerging Technologies, 2000Co-Authors: Michael A P Taylor, J Woolley, Rocco ZitoAbstract:Abstract The Transport Systems Centre (TSC) has developed an integrated Global Positioning System (GPS) – Geographical Information System (GIS) for collecting on-road traffic data from a probe vehicle. This System has been further integrated with the engine management System of a vehicle to provide time-tagged data on GPS position and speed, distance travelled, acceleration, fuel consumption, engine performance, and air pollutant emissions on a second-by-second basis. These data are handled within a GIS and can be processed and queried during the data collection (from a notebook PC in the vehicle) or saved to a file for later analysis. The database so generated provides a rich source of information for studies of travel times and delays, congestion levels, and energy and emissions. A case study application of the System is described focusing on studies of congestion levels on two parallel routes in a major arterial corridor in metropolitan Adelaide, South Australia. As part of these investigations, a discussion of the nature of traffic congestion is given. This provides both a general definition of traffic congestion and the discussion of a number of parametric measures of congestion. The computation of these parameters for the study corridor on the basis of data collected from the integrated GPS–GIS System is described. The GIS provides a database management platform for the integration, display, and analysis of the data collected from GPS and the in-vehicle instrumentation.
