Global Positioning System Methods Research Articles

Peak Speed in Gaelic Games: A Systematic Review of GPS Methods

Background: Peak speed is an essential physical quality in Gaelic games due to the offensive, defensive, and transitional nature of the sports. Objectives: The aims of the study were to systematically search the literature for studies examining peak speed during Gaelic games match-play using Global Positioning System (GPS) technology, to assess the GPS methodologies implemented and report normative values for peak speed by sport. Methods: Keywords were combined to search and identify studies reporting peak speed values recorded using GPS technology during Gaelic games match-play. Key details such as GPS brand/model, number of satellites connected, and firmware version were extracted. A risk of bias tool was designed to rate the level of detection bias within each study. Results: Twenty-one (N=21) studies met the inclusion criteria. Eight studies examined peak speed in hurling and men’s Gaelic football, respectively, while four camogie and one ladies Gaelic football study were identified. Twenty-nine percent (29%) of included studies were graded as having a high risk of bias in at least one category. Peak speeds between 7.81 to 9.97 m·s-1 were reported in hurling and men’s Gaelic football and between 5.88 to 7.45 m·s-1 in camogie and ladies’ Gaelic football. Conclusions: The dearth of literature examining peak speed in both female sports requires additional investigation, particularly in relation to the sprint profile of ladies Gaelic football. It is recommended that practitioners are cognisant of the methodological considerations which can be used as a ‘checklist’ to ensure accurate and reliable data are collected when using GPS technology to monitor peak speed.

Energy landscapes of Kodiak brown bears: a comparison of accelerometer and global positioning system-derived estimates

Within optimal foraging theory animals should maximize their net energy gain while minimizing energetic costs. Energetic expenditure in wild animals is therefore key to measure proxies of fitness. Accelerometers are an effective tool to study animal movement-based energetics, but retrieval of the device is usually required and often difficult. Accelerometers measure movement across three axes (x, y, and z) and can be calibrated to measures of oxygen consumption from captive animals, providing estimates of overall energy expenditure. Measuring energetic expenditures using a global positioning system (GPS) approach could provide an alternative method to study energetic ecology. This technique uses locomotor speeds across a range of slopes from successive GPS locations, which can be linked to the energy expenditure from captive individuals. We compared accelerometer and GPS methods of energetic expenditures in free-roaming brown bears (Ursus arctos) on the Kodiak Archipelago, Alaska, USA. We then applied the GPS method to examine how multiple factors influenced brown bear movement-based daily energetic expenditures (MDEE). We found that while the two energetic measurements differed (Wilcoxon signed rank test: V = 2116, p < 0.001), they were positively correlated (r = 0.82, p < 0.001). The GPS method on average provided 1.6 times greater energy estimates than the accelerometer method. Brown bears had lower MDEE during periods of high food abundance, supporting optimal foraging theory. Reproductive status and age did not influence MDEE, however movement rates had a positive linear relationship. Energetic ecology is important for understanding drivers of animal movements. Data from GPS collars can provide useful information on energetic expenditures, but should be validated for the specific taxa, ecosystem, and GPS sampling rate used. Additionally, while movement-based estimates of energy expenditure can elucidate the mechanisms driving habitat use decisions, they may not fully reflect an animal’s overall energy demands. Brown bear movement-based energetic expenditure was influenced by food abundance and movement rates, which highlighted the importance of access to prime foraging sites to enhance energetic efficiency.

Identifying Tourist Spatial and Temporal Patterns Using GPS and Sequence Alignment Method

This study identified the spatial and temporal patterns of national park visitors by combining global positioning system (GPS) technologies and surveys using the sequence alignment method (SAM) based on the concept of space–time path of time geography. Data were collected from a sample of 344 GPS tracks and questionnaires obtained from Gyeryongsan National Park in South Korea. A complex random stratified sampling method was employed to represent a national sample based on mobile positioning data. The result of the SAM analysis revealed that the derived visitor typologies constituted three groups from 83 unique paths extracted from 341 sequences. Significant intergroup differences were found for the paths based on average travel distance, average visit duration, and average travel speed. The main theoretical contribution of this study is in expanding the application of the theory by providing methodological improvements using SAM and GPS analysis of the theoretical basis of time geography.

A SINS/SAR/GPS Fusion Positioning System Based on Sensor Credibility Evaluations

A reliable framework for SINS/SAR/GPS integrated positioning systems is proposed for the case that sensors are in critical environments. Credibility is used to describe the difference between the true error and the initial setting standard deviation. Credibility evaluation methods for inertial measurement unit (IMU), synthetic aperture radar (SAR), and global positioning system (GPS) are presented. In particular, IMU credibility is modeled by noises and constant drifts that are accumulated with time in a strapdown inertial navigation system (SINS). The quality of the SAR image decides the credibility of positioning based on SAR image matching. In addition, a cumulative residual chi-square test is used to evaluate GPS credibility. An extended Kalman filter based on a sensor credibility evaluation is introduced to integrate the measurements. The measurement of a sensor is either discarded when its credibility value is below a threshold or the variance matrix for the estimated state is otherwise adjusted. Simulations show that the final fusion positioning accuracy with credibility evaluation can be improved by 1–2 times compared to that without evaluation. In addition, the derived standard deviation correctly indicates the value of the position error with credibility evaluation. Moreover, the experiments on an unmanned ground vehicle partially verify the proposed evaluation method of GPS and the fusion framework in the actual environment.

A Method of Low-Cost Pure-Digital GPS Disciplined Clock for Improving Frequency Accuracy and Steering Frequency Through TAF-DPS Frequency Synthesizer

One of the key characteristics of modern devices is time-awareness, which demands frequency source of good accuracy, precision, and stability. Unfortunately, all high-quality sources are expensive and bulky. An alternative is to add a companion clocking circuit to the primary source for performing frequency compensation in real time, under the guidance of a good time or frequency reference. The companion circuit aims at counteracting the primary source's systematic error and environment-induced variations. In this work, a frequency synthesizer having the features of small frequency granularity and fast frequency switching is adopted as such companion circuit. It functions as a tuning tool for periodically adjusting device's output frequency under the supervision of 1 PPS signal locked to global positioning system (GPS). This clock disciplining method can also be used for steering output frequency away from the specified value and toward a user-defined target. The main focus of this method is on improving frequency accuracy. The key advantage of the proposed method is low-cost and high-accessibility. It provides a new perspective, or devises a new instrument, for dealing with the sophisticated task of real-time frequency compensation. Our primary goal is to significantly simplify the engineering effort of this task without sacrificing the quality of clock signal noticeably. An field-programmable gate array (FPGA)-based system is created to demonstrate its capability of frequency compensation and steering. Further, 20 such systems are used to study the precision of a multi-node organization, as an example of using this instrument as a syntonization tool. The handy implementation on FPGA illustrates the advantage of DIY (do it yourself), making this method conveniently applicable for a variety of user scenarios.

Bimodal habitat use in brood parasitic Common Cuckoos (Cuculus canorus) revealed by GPS telemetry

Abstract Obligate brood parasitic birds have evolved a rare avian strategy for reproduction by laying eggs in the nests of other species. In doing so, their breeding ranges, but not necessarily their foraging habitats, have become intimately related to the nesting territories of their hosts. We studied home range sizes and distribution patterns in Common Cuckoos (Cuculus canorus) on their breeding grounds in central Hungary, where cuckoos parasitize only Great Reed Warblers (Acrocephalus arundinaceus) in channel-side reed-beds at a high frequency (&gt;50%). The geographic coordinates of tagged cuckoos were monitored by high-precision, remotely downloadable non-Platform Terminal Transmitter global positioning system (GPS) loggers, attached to 9 females and 6 males. Our results revealed bimodal use of habitat patches: (1) the home ranges of male and female cuckoos were packed densely along the channels where the hosts breed, and their distribution maps had high overlaps between sexes; (2) ~71% of cuckoos also visited nearby woodland patches, presumably for foraging, where the host species was not present. The size of cuckoo home ranges varied to an unusually great extent: 0.3–185 km2 as calculated by the minimum convex polygon method (85%), or 1–17 km2 when calculated by the more suitable kernel density estimation (KDE) method (Utilization Distribution 85%) for patchy habitats. Male and female cuckoos had similar home range sizes as estimated by the KDE method, consisting of 1–4 areas within the 2 habitat types of channel reed-beds and woodlands. No preference was revealed for night roosting locations between the 2 habitats or sexes. Female cuckoos were more likely to use reed-beds in the afternoons, when females parasitize host nests. Remote downloadable GPS methods offer an effective way of tracking cuckoos across large areas, but the estimation of home range sizes requires caution due to this species’ patchy and disconnected habitat use.

Acceptability of smartphone applications for global positioning system (GPS) and ecological momentary assessment (EMA) research among sexual minority men.

BackgroundEmerging research is using global positioning system (GPS) and ecological momentary assessment (EMA) methods among sexual minority men (SMM), a population that experiences multiple health disparities. However, we are not aware of any research that has combined these approaches among SMM, highlighting the need for acceptability and feasibility research. The purpose of this study was to examine the acceptability of implementing GPS and EMA research protocols using smartphone applications among SMM as well as related socio-demographic correlates.MethodsData come from a sample of SMM on a popular geosocial-networking app in Paris, France (n = 580). We assessed the acceptability of implementing GPS and EMA research protocols on smartphone apps as well as socio-demographic characteristics (i.e., age, sexual orientation, country of origin, employment status, and relationship status). We examined the anticipated acceptability of GPS and EMA data collection methods as well as socio-demographic correlates of acceptability of GPS and EMA methods.ResultsWe found that over half (54.1%) of the sample was willing to download a smartphone app for GPS-based research and we found that almost 60% of the participants were willing to download a smartphone app for EMA-based research. In total, 44.0% reported that they were willing to download both GPS and EMA apps. In addition, we found that older participants were less willing to download a smartphone app for EMA research than younger participants aged 18–24 (40–49 years: aPR = 0.40; 95% CI = 0.20, 0.78) and students were more willing to download smartphone apps for both GPS and EMA research (aPR = 1.41; 95% CI = 1.02, 1.95).ConclusionResults from this study suggest that using smartphone apps to implement GPS and EMA methods among some SMM are acceptable. However, care should be taken as segments of SMM are less likely to be willing to engage in this type of research.

Geomagnetic and Ionospheric Responses to the Interplanetary Shock Wave of March 17, 2015

The propagation of perturbation caused by the interplanetary shock wave of March 17, 2015 from the solar wind through the magnetosheath, magnetosphere, and ionosphere down to the Earth’s surface is analyzed. The onboard satellite measurements, global magnetometer network data, and records by the receivers of the global positioning system (GPS) providing the information about the total electron content (TEC) of the ionosphere are used for the analysis. By the example of this event, various aspects of the influence of the interplanetary shock wave on the near-Earth environment and ground-based engineering systems are considered. It is shown which effects of this influence are well described by the existing theoretical models and which ones need additional research. The formation of the fine structure of the magnetic impulse of the storm sudden commencement (SC)—the preliminary impulse (PI) and main impulse (MI)—is considered. The MI and compression of the magnetospheric magnetic field is observed by the GOES and RBSP satellites and on the geomagnetically conjugate stations; however, the PI was only noted on the Earth. The PI was detected in the afternoon sector practically simultaneously (within 1 min) with the shock wave impact on the magnetopause. The wave’s response to the SC includes the strongly decaying resonant oscillations of the magnetic shells and the magnetoacoustic cavity mode. This study supports the possibility of detecting the ionospheric response to the SC by the GPS method. The TEC response to the MI was detected in the auroral latitudes although not on every radio path. The TEC modulation can be associated with the precipitation of superthermal electrons into the lower ionosphere which is undetectable by riometers. The burst in the intensity of the geomagnetically induced currents caused by an interplanetary shock wave turns out to be higher than the currents during the storm’s commencement, although the SC’s amplitude is noticeably lower than the amplitude of the magnetic bay related to the substorm.

Odometry Method and Rotary Encoder for Wheeled Soccer Robot

The purpose of the study was to odometry method and rotary enconder for wheeled soccer robot. There are several methods to determine the accurate position of soccer robot movement in a room where the other is the best chosen odometry method. The method of determining the position of the wrong movement is used on the soccer robot. The researchers of soccer robot keep doing research and development, including the researchers from Indonesia. In Indonesia, there is a robot contest that is called Kontes Robot Indonesia (KRI) which has five categories, one of them is a Kontes Robot Sepak Bola Indonesia. In KRSBI there are 2 division. That are Humanoid robot and wheeled robot. Wheeled Soccer Robot has many ability such as searching ball, searching goal keeper, avoid the enemies, control the wheel’s speed and define the robot coordinate. In this research focused to determine the position of wheeled robot in the room. In previous research, previous authors used the Global Positioning System (GPS) and only know the position of robots outdoors. If a wheeled robot is applied indoors with the GPS method having an error (0.18%). Base on that condition, author use 3 Omni-wheels as the movement tool and use odometry method to define the position of the robot. This robot used Arduino as it main controller. Besides, rotary encoder is used to produce pulse for indicating movement, position, and direction of the robot which will go to the target of the ball. The author is expected to be able determine the coordinates of the robot in accordance with the actual robot position in the room and implement the odometry method to adjust the speed of the motor. Results from this research is position of odometry method (0.13%). Conclusion of this research odometry method more higher accuracy then GPS method.

Assessing the consistency of methods to measure travel behavior related to exposure to air pollution

Objective: To compare diary-reported trips and Global Positioning System (GPS) recording trips and identify the reasons for the discrepancies between two methods. Methods: The survey was conducted in Jiangning district in Nanjing city during July to September and November to December, 2015. Both the diary records and GPS method were used to investigate the travel behavior of 33 retired adults for 5 consecutive days. The GPS traces were display in Google Earth and then split into trips to compare with the diary records according to time and location. χ(2) test was used to analyze the influence of trip characteristics on misreporting rates of each method. Results: A total of 1 087 trips in the survey can be compared between the diary (n=909) and the GPS method (n=912). 7.3% (79/1 087) of the trips were only recorded by GPS method, and 11.8% (128/1 087) were only reported in the diary. Of the remaining 880 trips recorded by the both methods, 86.7% (763/880) matched each other, while 13.3% (117/880) did not. For the matched trips, the difference between the trip durations recorded by diary and GPS method was 2.0 (quartile was 6.0) minutes and the diary method overestimated about 25.0% trip durations when compared with the GPS method. The accuracy rates were 84.8%(903/1 065) and 86.9%(925/1 065) for diary and GPS method, respectively. Both methods were more likely to misreport the trip under 5 minutes. The misreporting rates of diary method for trips under 5 minutes were 6.8 times higher than trips over 30 minutes (21.7% vs 3.2%). The reporting accuracy was also significantly different among trips by different travel mode (P<0.05) for both methods, diary method had the lowest accuracy in reporting vehicles recorders (69.3%, 133/192), while GPS method was more accuracy in both biking (91.9%, 136/148) and vehicles recorders(89.6%, 172/192). The main reasons for misreporting by diary method were forgetting or unwilling to record and failing to record trips according to travel mode, while forgetting to carry GPS device, bad GPS signal and failing to locate the position were the main reasons for misreporting by GPS method. Conclusion: The majority of the trips reported in diary and GPS method are well consistent with each other. Both of the methods should be used simultaneously in the survey of time-activity pattern to improve the data quality.

Collecting Mobility Data with GPS Methods to Understand the HIV Environmental Riskscape Among Young Black Men Who Have Sex with Men: A Multi-city Feasibility Study in the Deep South.

While research increasingly studies how neighborhood contexts influence HIV among gay, bisexual and other men who have sex with men (MSM) populations, to date, no research has used global positioning system (GPS) devices, an innovative method to study spatial mobility through neighborhood contexts, i.e., the environmental riskscape, among a sample of Black MSM. The purpose of this study was to examine the feasibility of collecting two-week GPS data (as measured by a pre- and post-surveys as well as objectively measured adherence to GPS protocol) among a geographically-diverse sample of Black MSM in the Deep South: Gulfport, MS, Jackson, MS, and New Orleans LA (n = 75). GPS feasibility was demonstrated including from survey items, e.g. Black MSM reported high ratings of pre-protocol acceptability, ease of use, and low levels of wear-related concerns. Findings from this study demonstrate that using GPS methods is acceptable and feasible among Black MSM in the Deep South.

Acceptability and Feasibility of Using a Novel Geospatial Method to Measure Neighborhood Contexts and Mobility Among Transgender Women in New York City.

Purpose: To date, no studies utilizing global positioning system (GPS) technologies to measure mobility and environmental exposures have been conducted among a sample of transgender women despite the potential salient role neighborhood contexts may play in the health of this population. As such, the purpose of this study was to assess the acceptability and feasibility of a weeklong GPS protocol among a sample of transgender women in New York City.Methods: A sample of 14 transgender women residing in the New York City metropolitan area were recruited through community based methods to wear and charge a GPS device for 7 days to measure daily mobility. The acceptability of these methods was assessed using a pre- and postprotocol survey and their feasibility was measured using objective data derived from the GPS device. Pre- and postprotocol survey measures were compared using McNemar's test.Results: Participants reported high ratings of preprotocol acceptability, as well as few concerns regarding safety, appearance, and losing the device, all of which were maintained after completing the protocol. All 14 devices that were distributed were returned. In addition, all 14 participants had GPS data for at least 1 h on 1 day, and nine participants (64.3%) had at least 8 h of GPS data on all days.Conclusion: The findings of this pilot study demonstrate that the GPS methods are both acceptable and feasible among this sample of transgender women. GPS devices may be used in research among transgender women to understand neighborhood determinants of HIV and other STIs.

Sustainable Surface Deformation Related with 2006 Augustine Volcano Eruption in Alaska Measured Using GPS and InSAR Techniques

Augustine volcano, located along the Aleutian Arc, is one of the most active volcanoes in Alaska and nearby islands, with seven eruptions occurring between 1812 and 2006. This study monitored the surface displacement before and after the most recent 2006 eruption. For analysis, we conducted a time-series analysis on data observed at the permanent GPS(Global Positioning System) observation stations in Augustine Island between 2005 and 2011. According to the surface displacement analysis results based on GPS data, the movement of the surface inflation at the average speed of 2.3 cm/year three months prior to the eruption has been clearly observed, with the post-eruption surface deflation at the speed of 1.6 cm/year. To compare surface displacements measurement by GPS observation, ENVISAT(Environmental satellite) radar satellite data were collected between 2003 and 2010 and processed the SBAS(Small Baseline Subset) method, one of the time-series analysis techniques using multiple InSAR(Interferometric Synthetic Aperture Radar) data sets. This result represents 0.97 correlation value between GPS and InSAR time-series surface displacements. This research has been completed precise surface deformation using GPS and time-series InSAR methods for a detection of precursor symptom on Augustine volcano.

Feasibility and Acceptability of Global Positioning System (GPS) Methods to Study the Spatial Contexts of Substance Use and Sexual Risk Behaviors among Young Men Who Have Sex with Men in New York City: A P18 Cohort Sub-Study.

BackgroundNo global positioning system (GPS) technology study has been conducted among a sample of young gay, bisexual, and other men who have sex with men (YMSM). As such, the purpose of this study was to evaluate the feasibility and acceptability of using GPS methods to understand the spatial context of substance use and sexual risk behaviors among a sample of YMSM in New York City, a high-risk population.MethodsData came from a subsample of the ongoing P18 Cohort Study (n = 75). GPS feasibility and acceptability among participants was measured with: 1) a pre- and post-survey and 2) adherence to the GPS protocol which included returning the GPS device, self-report of charging and carrying the GPS device as well as objective data analyzed from the GPS devices. Analyses of the feasibility surveys were treated as repeated measures as each participant had a pre- and post-feasibility survey. When comparing the similar GPS survey items asked at baseline and at follow-up, we present percentages and associated p-values based on chi-square statistics.ResultsParticipants reported high ratings of pre-GPS acceptability, ease of use, and low levels of wear-related concerns in addition to few concerns related to safety, loss, or appearance, which were maintained after baseline GPS feasibility data collection. The GPS return rate was 100%. Most participants charged and carried the GPS device on most days. Of the total of 75 participants with GPS data, 75 (100%) have at least one hour of GPS data for one day and 63 (84%) had at least one hour on all 7 days.ConclusionsResults from this pilot study demonstrate that utilizing GPS methods among YMSM is feasible and acceptable. GPS devices may be used in spatial epidemiology research in YMSM populations to understand place-based determinants of health such as substance use and sexual risk behaviors.

HEIGHT ACCURACY BASED ON DIFFERENT RTK GPS METHOD FOR ULTRALIGHT AIRCRAFT IMAGES

Abstract. Height accuracy is one of the important elements in surveying work especially for control point’s establishment which requires an accurate measurement. There are many methods can be used to acquire height value such as tacheometry, leveling and Global Positioning System (GPS). This study has investigated the effect on height accuracy based on different observations which are single based and network based GPS methods. The GPS network is acquired from the local network namely Iskandar network. This network has been setup to provide real-time correction data to rover GPS station while the single network is based on the known GPS station. Nine ground control points were established evenly at the study area. Each ground control points were observed about two and ten minutes. It was found that, the height accuracy give the different result for each observation.

Relations between the GNSS, InSAR, and the other techniques for prediction of earthquakes

It is a well-known fact that the earthquakes have a lot of different parameters. Modern technology allows us to observe an important part of these settings. For example, when an earthquake occurs, its location, time, and depth, etc., values are measured by a seismometer. Recently, using the modern technologies, Global Positioning System (GPS) and Interferometric Synthetic Aperture Radar (InSAR) give us a chance to predict earthquakes in the short or long term. For avoiding the destruction the force of an earthquake can bring to human beings, it is inevitable to use the newer techniques. To predict out about the expected main shock, someone must begin to study firstly earthquakes which have already occurred. In this research, the seismometer and acceleration-meter data have been evaluated and compared by the geodetic measuring data of the InSAR and GPS data for Van earthquake on 23 October 2011. The area of research made out by the InSAR technique and the deformations produced by the GPS technique are being tested under centimeter precision. Additionally, the ionospheric total electron content values obtained by the GPS method have been considered, and the ionospheric distortions acquired from the closest Continuously Operating Reference Stations-Turkey stations, particularly Muradiye station, have been observed. Also, they have been interpreted geophysically.

Ailanthus altissima (tree of heaven): Spread and harmfulness in a case-study urban area

Among the woody and shrubby weeds colonising non-crop areas in the Apulia Region (South Italy), Ailanthus altissima (tree of heaven), an exotic invasive species, is one of the worst, because of its fast growth and root-sucker production. It reaches the heart of protected areas and spreads everywhere in urban and peri-urban areas creating dense stands. As there are no official monitoring protocols for weed mapping, a method based on real-time global positioning system (GPS) on satellite maps was set up. Due to this method, the distribution, spread, size, density and harmfulness of A. altissima were assessed across the wide urban area of Bari (South Italy) by mapping all the individual plants and areas/stands of plants. In Bari, along a total of 76 km of roads mapped, 170 very large (diameter >18 cm), 231 large (diameter 8–18 cm), 130 medium (diameter 3–8 cm), 53 small (diameter < 3 cm) single plants, and 70 high, 63 medium and 13 low density areas were detected. This indicated that A. altissima (tree of heaven) was very widespread in the study area. Moreover, 35 types of damage or potential risks were recorded covering functional, environmental, health and safety and aesthetic aspects and then classified according to frequency and location. The real-time GPS method proved to be very useful for providing a speedy and accurate record of the data.

듀얼 확장 칼만 필터를 이용한 쿼드로터 비행로봇 위치 정밀도 향상 알고리즘 개발

The fusion of the GPS (Global Positioning System) and DR (Dead Reckoning) is widely used for position and latitude estimation of vehicles such as a mobile robot, aerial vehicle and marine vehicle. Among the many types of aerial vehicles, grater focus is given on the quad-rotor and accuracy of the position information is becoming more important. In order to exactly estimate the position information, we propose the fusion method of GPS and Gyroscope sensor using the DEKF (Dual Extended Kalman Filter). The DEKF has an advantage of simultaneously estimating state value and a parameter of dynamical system. It can also be used even if state value is not available. In order to analyze the performance of DEKF, the computer simulation for estimating the position, the velocity and the angle in a circle trajectory of quad-rotor was done. As it can be seen from the simulation results using own proposed DEKF instead of EKF on own fusion method in the navigation of a quad-rotor gave better performance values.

EstimatingRhododendron maximumL. (Ericaceae) Canopy Cover Using GPS/GIS Technology

ABSTRACT In the southern Appalachians, Rhododendron maximum L. (Ericaceae) is a key evergreen understory species, often forming a subcanopy in forest stands. Little is known about the significance of R. maximum cover in relation to other forest structural variables. Only recently have studies used Global Positioning System (GPS) technology as a field-based method to map the perimeter of shrub patches as a means of estimating canopy cover. We assessed the viability of using GPS technology to accurately measure R. maximum canopy cover in mountainous terrain; and we compared canopy cover to other R. maximum abundance variables, forest structural attributes, and environmental factors. We selected forty 20 × 40 m permanent plots at Coweeta Hydrologic Laboratory in western North Carolina to employ a variety of methods (visual estimates, GPS, and x-y coordinate measurements) to estimate canopy cover of R. maximum within each plot. We found a positive relationship between the GPS method and the more accurate x-...

Combining global positioning system and accelerometer data to determine the locations of physical activity in children

National trends indicate that children and adolescents are not achieving sufficient levels of physical activity. Combining global positioning system (GPS) technology with accelerometers has the potential to provide an objective determination in locations where youth engage in physical activity. The aim of this study was to identify the optimal methods for collecting combined accelerometer and GPS data in youth, to best locate where children spend time and are physically active. A convenience sample of 24 mid-school children in Massachusetts was included. Accelerometers and GPS units were used to quantify and locate childhood physical activity over 5 weekdays and 2 weekend days. Accelerometer and GPS data were joined by time and mapped with a geographical information system (GIS) using ArcGIS software. Data were collected in winter, spring, summer in 2009-2010, collecting a total of 26,406 matched datapoints overall. Matched data yield was low (19.1% total), regardless of season (winter, 12.8%; spring, 30.1%; summer, 14.3%). Teacher-provided, pre-charged equipment yielded the most matched (30.1%; range: 10.1-52.3%) and greatest average days (6.1 days) of data. Across all seasons, children spent most of their time at home. Outdoor use patterns appeared to vary by season, with street use increasing in spring, and park and playground use increasing in summer. Children spent equal amounts of physical activity time at home and walking in the streets. Overall, the various methods for combining GPS and accelerometer data provided similarly low amounts of combined data. No combined GPS and accelerometer data collection method proved superior in every data return category, but use of GIS to map joined accelerometer and GPS data can demarcate childhood physical activity locations.