Global Positioning System Equipment Research Articles

Anatomical characterization of Ocotea indecora Schott wood along a 300m altitude gradient

This study aimed to evaluate the impact of altitude on the anatomical characteristics of Ocotea indecora wood under various relief conditions in Cunha, São Paulo. Non-destructive stem samples of Ocotea indecora were collected at three altitudes within the Cunha Nucleus of the Serra do Mar State Park (1300, 1200, and 1000 m). Five non-destructive samples were taken at each altitude around the diameter at breast height (DBH) of selected trees. Trees above 1250 m were situated in plateau areas, while the remaining sampled trees were situated in escarpment areas with slopes ranging from 30 to 90%. The geolocation of sampled trees was performed using global positioning system equipment. The samples were processed following standard wood anatomy techniques. Significant differences were observed, but only in the fiber diameter of samples collected between 1000 m and 1300 m. At 1300m, fiber diameter showed the highest values, while the lowest fiber diameter was found in trees sampled at 1000 m. According to cluster dendrogram analysis, considering all analyzed variables, altitudes of 1200 m and 1300 m were grouped together, differing from the altitude of 1000m, which formed a separate cluster. Generally, anatomical elements correlate differently among themselves depending on the altitude gradient.

An Experiment for Outdoor GPS Localization Enhancement using Kalman Filter with Multiantenna Consumer-Grade Sensors

Consumer-Grade global positioning system (GPS) is widely used in many domains. The obvious issue of this consumer-grade device is low accuracy and reading fluctuation results. In terms of using an application that requires a more precise location, the output could be difficult. In this study, the authors deploy various methods to reduce the global positioning system data fluctuation and present field test results. Two main types of the device worked together to collect data from global positioning systems, such as Microcontroller for algorithm processing and presenting data and global positioning system receivers for receiving data from a satellite. We combine three global positioning system modules to received signals in a single device and test calculated data compared with the Kalman filtering methods in many cases, including moving and static devices. Implementing the Standard Kalman Filter to multiple global positioning system Modules has improved the constancy of cheap global positioning system equipment. The experiment algorithm is presented significant improvement to overcome the retrieved data fluctuation problem. This study's contribution will enable creating a cheap global positioning system locator device for various applications that require more accuracy than the standard consumer-grade receiver.

Learning Traffic as Images for Incident Detection Using Convolutional Neural Networks

The timely and accurate detection of traffic incidents is beneficial to reduce associated economic losses and avoid secondary crashes. Inspired by the impressive success of the image classification algorithms, especially convolutional neural networks (CNNs), this study proposes a novel framework to detect highway traffic incidents by learning the traffic state as images. In such a framework, the probe vehicles equipped with the global positioning system equipment are used to obtain data. The Gramian Angular Difference Fields and Piecewise Aggregation Approximation algorithms are used to convert the link speed time series data into images. CNNs can extract the traffic features based on these images and consider an incident detection problem as a binary classification task. Further, the effectiveness of the proposed framework is evaluated by applying it to detect the traffic in a real-world environment, i.e., the Guangzhou Airport Expressway. The results illustrate that the proposed model outperforms several other algorithms with respect to almost all the performance indexes, including the detection rate with different false alarm rates and the area under the receiver operating characteristic curve.

Estimating hotspots using a Gaussian mixture model from large-scale taxi GPS trace data

Abstract The data collected from taxi vehicles using the global positioning system (GPS) traces provides abundant temporal-spatial information, as well as information on the activity of drivers. Using taxi vehicles as mobile sensors in road networks to collect traffic information is an important emerging approach in efforts to relieve congestion. In this paper, we present a hybrid model for estimating driving paths using a density-based spatial clustering of applications with noise (DBSCAN) algorithm and a Gaussian mixture model (GMM). The first step in our approach is to extract the locations from pick-up and drop-off records (PDR) in taxi GPS equipment. Second, the locations are classified into different clusters using DBSCAN. Two parameters (density threshold and radius) are optimized using real trace data recorded from 1100 drivers. A GMM is also utilized to estimate a significant number of locations; the parameters of the GMM are optimized using an expectation-maximum (EM) likelihood algorithm. Finally, applications are used to test the effectiveness of the proposed model. In these applications, locations distributed in two regions (a residential district and a railway station) are clustered and estimated automatically.

The influence of grounding on GPS receiver differential code biases

The Global Positioning System (GPS) has become an effective tool for estimating ionospheric total electron content (TEC). One of the critical factors affecting ionospheric TEC estimation from GPS data is the differential code biases (DCBs) inherent in both GPS receivers and satellites. To investigate the factor that affects the receiver DCB, we consider the relationship between the receiver DCB and the grounding of an antenna. GPS data from 9 stations in South Korea from three periods (the years 2009, 2014, and 2017) were used in the analysis. It was found that a significant jump (∼8–13 ns, or ∼ 23–37 TECU) in hourly DCB time series occurred simultaneously at the two different sites when an antenna is changed from a grounded to the non-grounded state. Thus, our study clearly identifies that the grounding of GPS equipment is a factor of the receiver DCB changes.

Incident detection methods using probe vehicles with on-board GPS equipment

Mobile communication instruments have made detecting traffic incidents possible by using floating traffic data. This paper studies the properties of traffic flow dynamics during incidents and proposes incident detection methods using floating data collected by probe vehicles equipped with on-board global positioning system (GPS) equipment. The proposed algorithms predict the time and location of traffic congestion caused by an incident. The detection rate and false rate of the models are examined using a traffic flow simulator, and the performance measures of the proposed methods are compared with those of previous methods.

A Process Chart to Design Experiential Learning Projects

A high-impact practice is to incorporate experiential learning projects when teaching difficulty subject matters so as to enhance students’ understanding and interest in the course content. But, there is limited research on how to design and execute such projects. Therefore, we propose a framework based on the processes described by the Project Management Body of Knowledge and the instructional characteristics known to influence the quality of student learning experiences. Its effectiveness is evaluated by analyzing a case study of mapping a municipal storm drain system using global positioning system equipment. The results of the evaluation revealed that the project facilitated the students’ understanding of the pertinent technical concepts, helped them realize the importance of teamwork, and provided them with an opportunity to contribute in a meaningful way to enhance a community’s ability to cope with major rainfall events. We develop a process chart based on the framework and expect its use in designing and implementing real-world experiential learning projects in courses will provide a win–win situation for the community, students, and faculty members.

A survey on orthopedic injuries during a marathon sled dog race.

PurposeThis prospective observational study aimed to describe and quantify orthopedic injuries (OI) during a marathon sled dog race that led to discontinuation of racing (dropped dogs [DDs]) and to suggest potential associations with risk factors during the event.Study designProspective observational study.AnimalsA total of 989 Nordic breed endurance sled dogs that participated in the 2011 Iditarod Sled Dog Race. Data were collected via an extensive questionnaire, medical records, and speed calculations based on Global Positioning System equipment on each dog sled. OI risk factors and DD incidence were statistically analyzed on dogs and teams completing at least half the race distance, including Student’s t-test, Pearson’s chi-squared test, Poisson regression, and various frailty analysis models as indicated. Significance was set at P<0.10 for inclusion in the models with trends established at P≤0.10 and significance declared at P<0.05.ResultsQuestionnaire response was 40.3%. DD incidence was 38.3%, most often due to OI (50.6%). OI occurred most frequently in the thoracic limb (43.3%) compared with pelvic limb injuries (7.3%). Increased speed was associated with fewer shoulder injuries (Ratio=0.65, P=0.03). Carpal injuries were positively related with increased conditioning distance (defined as training miles; Hazard ratio =1.61, P=0.02). The risk to become a DD decreased with every year of increased age of the dogs (Hazard ratio =0.92, P=0.03).ConclusionOI, specifically of the shoulder and carpus, are common in marathon sled dogs. Injury risk may be speed-related and decreases with increasing age of the dog. Further study of environmental, dietary, and trail conditions in sled dog racing orthopedic research is needed.

Incident Detection Methods Using Probe Vehicles with On-board GPS Equipment

Mobile communication instruments have made detecting traffic incidents possible by using floating traffic data. This paper studies the properties of traffic flow dynamics during incidents and proposes incident detection methods using floating data collected by probe vehicles equipped with on-board global positioning system (GPS) equipment. The proposed algorithms predict the time and location of traffic congestion caused by an incident. The detection rate and false rate of the models are examined using a traffic flow simulator, and the performance measures of the proposed methods are compared with those of previous methods.

Link calibration against receiver calibration: an assessment of GPS time transfer uncertainties

We present a direct comparison between two different techniques for the relative calibration of time transfer between remote time scales when using the signals transmitted by the Global Positioning System (GPS). Relative calibration estimates the delay of equipment or the delay of a time transfer link with respect to reference equipment. It is based on the circulation of some travelling GPS equipment between the stations in the network, against which the local equipment is measured. Two techniques can be considered: first a station calibration by the computation of the hardware delays of the local GPS equipment; second the computation of a global hardware delay offset for the time transfer between the reference points of two remote time scales. This last technique is called a ‘link’ calibration, with respect to the other one, which is a ‘receiver’ calibration. The two techniques require different measurements on site, which change the uncertainty budgets, and we discuss this and related issues. We report on one calibration campaign organized during Autumn 2013 between Observatoire de Paris (OP), Paris, France, Observatoire de la Côte d'Azur (OCA), Calern, France, and NERC Space Geodesy Facility (SGF), Herstmonceux, United Kingdom. The travelling equipment comprised two GPS receivers of different types, along with the required signal generator and distribution amplifier, and one time interval counter. We show the different ways to compute uncertainty budgets, leading to improvement factors of 1.2 to 1.5 on the hardware delay uncertainties when comparing the relative link calibration to the relative receiver calibration.

Predictive speed models for two-lane rural roads using GPS equipment

This research is aimed at verifying the effectiveness of a low cost global positioning system (GPS) installed in a medium passenger car for modelling drivers speed behaviour and providing predictive models of operating speed and speed differential. This study proposed new speed models specific for Italian two-lane rural roads, based on the analysis of 36 speed profiles performed along a road segment characterised by 13 tangent-curve configurations. A predictive model for operating speed on tangent identified the length of the tangent and the local grade as the most significant explanatory variables. Moreover a predictive model of operating speed on curve revealed the length and the radius of the horizontal curve and the local grade as predictors. Finally tangent-curve speed variations were evaluated and a model for predicting 85MSR was developed. The length of the approaching tangent and the deflection angle were found the most significant predictors.

Muscle Damage, Endocrine, and Immune Marker Response to a Soccer Match

This study represents the first time that muscle damage, endocrine, and immune markers have been measured, together with activity profile, during a competitive soccer match. Seven semiprofessional soccer players participated in a competitive league match. Blood and saliva samples were obtained 1 hour before kick off and immediately postmatch. Global positioning system equipment was used to measure heart rate and activity profile data throughout the match. Percentage increase in creatine kinase (CK) and myoglobin (MYO) concentrations was correlated with the number of sprints performed during the match (r = 0.88, p = 0.019; r = 0.75, p = 0.047, respectively). Creatine kinase increased by 84% (p = 0.17) from prematch to postmatch, whereas MYO increased by 238% (p = 0.05). Players performed 39 ± 18 sprints during the course of the match. Cortisol increased by 78% (p = 0.103), whereas testosterone increased significantly by 44% (p = 0.004). No differences were seen from prematch to postmatch in the testosterone to cortisol ratio, immunoglobulin (Ig) A, IgM, or IgG. Sprinting is correlated with changes in CK and MYO and may therefore be associated with muscle damage in semiprofessional soccer players.

Older Driver Training Using Video and Global Positioning System Technology--a Randomized Controlled Trial

There is emerging evidence that older driver training programs with on-road instruction are more effective than driver education programs that are conducted only in the classroom. Although most programs have provided this additional in-vehicle training with a driving instructor and a dual-braked vehicle, technology could assist in providing this feedback. It was hypothesized that participants who received video and global positioning system (GPS) feedback (Video group) in addition to classroom education would improve to a greater extent than those who received a classroom-based course alone (Education) or Control participants. Fifty-four participants (32 men and 22 women), 70-89 years old, randomized to one of the three groups, completed the study. All participants underwent pre- and postintervention driving tests, in their own vehicle, on a standardized route, that were recorded with video and GPS equipment. The Video group met with a driving instructor to receive feedback on their driving errors in their preintervention driving test. A blinded assessor scored all driving tests in random order. The Video group significantly reduced their driving errors by 25% (p < .05) following the intervention, whereas the other two groups did not change significantly. Fifty-two percent of participants from the Video group improved their global safety rating, whereas only 5.3% in the Control and 22.2% in the Education groups did. This study suggests that direct driving feedback using video and GPS technology could be an effective and novel means to provide older driver education.

Dune and Vegetation Stability at South Padre Island, Texas, United States of America

Abstract Padre Island is the longest of five barrier islands occurring along the Texas Gulf Coast. South Padre Island is separated from the northern two-thirds of the island by the Mansfield Channel. The composition and pattern of vegetation on South Padre Island are relatively well known, but data on the interrelationship of dune and vegetation stability are lacking. We hypothesized that (1) there should be an inverse relationship between elevation change and percent cover on transects across the nearshore dunes of South Padre Island; and (2) percent cover, species composition, and species importance should be most stable where elevation change was least. We tested these hypotheses using three study sites differing in vegetation abundance. Elevation measurements were taken at 1.0-m intervals along three transects at each site using survey-grade Global Positioning System equipment. Vegetation abundance was determined in 10-m intervals along each transect. No sites or topographic zones were devoid of eleva...

Laser profiling over Antarctic ice streams: methods and accuracy

AbstractWe assess the accuracy and precision of the U.S. National Science Foundation’s Support Office for Aerogeophysical Research (SOAR) laser profiling system for mapping topography and detecting surface elevation changes of West Antarctic ice streams. The procedures used to process, calibrate and validate the laser, navigation and global positioning system (GPS) data are presented. The primary objective is to produce surface elevations with the best possible resolution. Repeat surveys of a grid of lines over Whillans Ice Stream and Ice Streams C and E were conducted in the 1997/98 and 1999/2000 seasons. The procedure has been calibrated using special test flights conducted over areas that have been surveyed with precise geodetic GPS equipment mounted on snow-mobiles. After calibration, agreement between the two surfaces is ±10 cm rms. The accuracy and precision of the procedure have been evaluated at points where laser flight-lines cross over one another. The accuracy of the system is found to range from 0.09 to 0.22 m.

Evaluation of a digital echo sounder system for detection of submersed aquatic vegetation

A technique is presented for rapid detection of submersed aquatic vegetation (SAV) using a high-frequency, high-resolution digital echo sounder linked with global positioning system equipment. The acoustic reflectivity of SAV allows for detection and explicit meaqsurement of canopy geometry using a digital signal processing algorithm described here. Comparing output data from this system with physical measurements shows good detection and measurement performance over a wide range of conditions for freshwater tape grass (Vallisneria americana) and seagrasses (Thalassia testudinum, Halodule wrightii, andSyringodium filiforme) in a sandy-bottom, south Florida estuary. The range of environmental conditions for which the system can be used is defined. Based on these measured performance data and a review of existing literature, this system appears to fill a gap in the inventory of established methods for measuring the distribution and abundance of submersed macrophytes.

Observations of a reversal in vertical and horizontal strain-rate regime during a motion event on Unteraargletscher, Bernese Alps, Switzerland

AbstractDuring a motion event on Unteraargletscher, Bernese Alps, Switzerland, in spring 1996, surface velocities were measured up to eight times a day at four different locations along the central flowline using global positioning system equipment. In addition, accumulated vertical strains over the uppermost 50 and 100 m were measured at a location where the total ice thickness is 260 m. The motion event was accompanied by high horizontal and vertical strain rates as compared to annual mean values. A reversal in strain regime was observed, with horizontal strain rates changing to extension while vertical strain rates became compressive. This strain-rate reversal coincided, within the temporal resolution of the data, with a maximum in vertical ice displacement at the surface.Within a day, variations in vertical strain from 0.04 a−1 to −0.06 a−1 were observed over the uppermost 100 m. Vertical stretching is estimated to have contributed to at least 20% of the anomalous vertical ice movement at the surface. There were significant differences between measured longitudinal strain, averaged over a distance corresponding to a few ice thicknesses, and measured vertical strain. In spring 1997 a similar, but more detailed, set of measurements was collected at the same measuring site, and vertical strain rates were found to vary non-uniformly with depth, with the largest values closest to the surface.

Combined Analysis of Real-Time Kinematic GPS Equipment and Its Users for Height Determination

Ellipsoidal and Australian Height Datum heights have been deter- mined for a 60-point control network from five base stations by three separate users using three different makes of real-time kinematic (RTK) global positioning system (GPS) equipment. This was to determine whether these RTK GPS surveys (i.e. equipment and users combined) can meet vertical accuracy specifications for con- tract work with Main Roads Western Australia. A comparison of the differences between the RTK GPS ellipsoidal heights and the control indicates 51 mm (95% confidence) accuracy, accounting for errors in the control network. Likewise, the difference between the RTK GPS-derived Australian Height Datum heights and the control indicates 53 mm (95% confidence) accuracy. However, there was an increasing number of failed RTK GPS position solutions with increasing baseline length, which had to be omitted from these statistics.

Using Global Positioning System to Improve School Bus Routing and Scheduling

School bus routing and scheduling in North Carolina are completed by using the transportation information management system (TIMS), according to state legislative mandate. TIMS uses an optimization algorithm to generate acceptable route alternatives to best serve the transported students and to minimize the required number of buses. This algorithm uses link travel times and speeds encoded in the geocode (digitized map) to determine the routes for each school bus in the state. The speeds and travel times used by TIMS have no mathematical basis and have not been calibrated for conditions in North Carolina. The encoded speeds are simply reductions of the posted speed limit to account for student stops and the bus’s general inability to reach the posted speed. There is a need for models that can accurately estimate link travel times and student loading times so that TIMS can provide better estimates of optimal routes. On-board mobile Global Positioning System equipment was used on several school bus routes throughout the state to collect the data necessary for model development and validation. Two student loading time models were developed: a general model that can be used in an urban, a suburban, or a rural area, and an urban-specific model, which involves fewer predictor variables. Link travel-time models were developed according to the two most pertinent factors: link length and traffic control device type at the link’s end. Model validation was successful, and now more-efficient school bus routes can be developed because of more-accurate geocode speed and travel-time estimates.

Passive VHF radar for ionospheric physics

Recent technological advances enable a new class of passive radar instruments. These radars have no dedicated transmitter, observing serendipitous scatter of existing sources. Such radars may have very high performance and cost far less than conventional radars. The resulting equipment is essentially reduced to simple antennas, desktop computers, and Global Positioning System equipment. The safety hazards, interference problems, licensing issues, and financial costs associated with high-power transmitters are conspicuously absent. We will offer general design considerations and describe our own instrument, which observes the scatter of commercial FM broadcasts. Our system provides far better range and Doppler resolution than any conventional radar used in ionospheric coherent scatter studies, and is completely free of any range or Doppler aliasing problems. There are two principal drawbacks to passive radars: the “front end” signal processing cost is very large, and there is a significant data transport problem. However, spectacular advances in low-cost computing and internet bandwidth have rendered these problems quite easy to solve.