1,720,958 research outputs found
Dual Frequency, Carrier Phase Differential GPS Augmentation
No full textFor many roadway applications, high-accuracy in-lane level vehicle position information is desired. Unfortunately, in many roadway environments GPS dead zones hinder sufficient GPS position accuracy. These roadway environments include underpasses, tree canopies, urban canyons, and any other locations where the view to the sky is limited.
This report introduces a high-accuracy position estimator that augments GPS in areas where short-term (<200 meter and < 15 second) GPS dead zones exist. The position estimator fuses differential GPS (DGPS) position measurements, yaw rate measurements, and two-dimensional velocity measurements to provide in-lane level accuracy position estimates. The estimator increases the availability of high-accuracy position estimates for applications that demand continuous high-accuracy in-lane level positioning, such as lane departure warning systems.
The position estimator was evaluated and the position accuracy was quantified. Seven vehicles were outfitted with the position estimator system. Data was collected for 460 DGPS outages and the accuracy of the system was analyzed. From the analysis the position accuracy of the estimator could be approximated based on the distance and time since the DGPS outage began. This analysis provides a level of confidence in the position estimates as a function of distance and time elapsed from the start of a DGPS outage. This level of confidence measure allows applications to have a means to reject position estimates based on the outage time and distance if those estimates are projected to have lower accuracy than the application requires.Arpin, Eddie; Newstrom, Bryan; Shankwitz, Craig. (2011). Dual Frequency, Carrier Phase Differential GPS Augmentation. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/104559
Bus Rapid Transit Technologies: Assisting Drivers Operating Buses on Road Shoulders: Volume 1
No full textThe FTA has identified the concept of Bus Rapid Transit as a means to increase the efficiency of transit operations while maintaining transit's proven safety record. According to the FTA website www.fta.dot.gov, "BRT combines the quality of rail transit and the flexibility of buses. It can operate on exclusive transitways, HOV lanes, expressways, or ordinary streets. A BRT system combines intelligent transportation systems technology, priority for transit, cleaner and quieter vehicles, rapid and convenient fare collection, and integration with land use policy."
Because of the limited right-of-way available to build new (and possibly dedicated) lanes for BRT operations, the FTA has identified lane assist as an emerging technology, which will enable deployment of BRT systems. The premise behind lane assist technology is to increase the safety of BRT vehicles as they operate in the more unique environments, such as narrow lanes. Lane assist technology will allow BRT vehicles to operate at the desired higher operating speeds while maintaining the safety of the passengers, BRT vehicle and the motoring public.ITS InstituteAlexander, Lee; Cheng, Pi-Ming; Donath, Max; Gorjestani, Alec; Newstrom, Bryan; Shankwitz, Craig; Trach, Walter. (2003). Bus Rapid Transit Technologies: Assisting Drivers Operating Buses on Road Shoulders: Volume 1. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/809
Technology Enabling Near-Term Nationwide Implementation of Distance Based Road User Fees
No full textThis report describes a system meant for near-term deployment that directly determines the distance traveled by a vehicle and uses this as a basis for charging a fee that reflects road use. An in-vehicle device with access to the vehicle data bus and power through a single standard connector available on all passenger vehicles since 1996, electronically calculates the distance and then securely communicates relevant information to a “back office” for processing and transferring accumulated fees from the user to the appropriate government jurisdiction. Also described are means for providing payment (and receiving credit for motor fuel use taxes paid at the pump) while also ensuring compliance, enforcement, transparency and privacy. Communication is via text messaging, available wherever cellular service is accessible. No new wireless infrastructure is needed. The in-vehicle device distinguishes distance traveled by state or by other regions of interest e.g., rural vs. urban areas, using the same cellular technology that is used for communications. Aggregating distance based on rural vs. urban travel can facilitate different pricing policies for these different road users. Neither a GPS receiver nor longitude/latitude position data is necessary. However, higher resolution position sensing can be added to the core platform as needed based on policy objectives, e.g., to consider alternate pricing for specific road facilities.Donath, Max; Gorjestani, Alec; Shankwitz, Craig; Hoglund, Richard; Arpin, Eddie; Cheng, PiMing; Menon, Arvind; Newstrom, Bryan. (2009). Technology Enabling Near-Term Nationwide Implementation of Distance Based Road User Fees. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/97660
Driver Assistive Systems for Rural Applications: A Path to Deployment, Volume 1
No full textDeployment of any system is driven by market demand and system cost. Initial deployment of the Intelligent Vehicle Lab Snowplow Driver Assistive System (DAS) was limited to a 45 mile section of Minnesota Trunk Highway 7 west of I-494 and east of Hutchinson MN. To better gage demand and functionality, St. Louis and Polk Counties in Minnesota operationally tested the system during the winter of 2003-2004; Polk County also tested during the winter of 2004-2005. Operational benefits were found to be drastically different in the two counties. Low visibility was not an issue with the St. Louis County snowplow routes, so the system offered few benefits. In contrast the topology of Polk county is flat, with almost no trees. High winds combined with few visual cues create significant low visibility conditions. Polk County was pleased with their original system, and obtained a second system and tested it operationally during the 2004-2005 winter. The experience of these two counties is documented in this volume, Volume One. A key component of the DAS is a high accuracy digital map. With the exception of the mapping process, the present cost of the DAS is well documented. Volume Two describes a system designed to collect and process geospatial data to be used by driver assitive system, and the costs and time associated with collecting map data, and creating a map from that data. With cost data complete, counties can determine whether to acquire these systems.Local Road Research BoardCheng, Pi-Ming; Gorjestani, Alec; Newstrom, Bryan; Shankwitz, Craig; Trach, Walter. (2005). Driver Assistive Systems for Rural Applications: A Path to Deployment, Volume 1. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/984
Advanced BRT Volume II: Innovative Technologies for Dedicated Roadways
No full textPresented herein is a novel approach to vehicle positioning using RFID technology (Vehicle Positioning System, or VPS). By installing in the road RFID tags encoded with road name or other designation, the specific lane, the direction of travel, and the longitudinal distance from a known reference, a vehicle outfitted with an RFID tag reader can determine its position each time it passes over and reads a tag, thus, providing precisely the information needed for many ITS applications – the longitudinal position of a vehicle in a particular lane on a particular road of the transportation network. Knowledge of lane of travel and distance from a known reference provided by VPS enables many transit applications, including headway control of bus platoons, merge/lane change assistance, rear-end collision avoidance, and bay mark-up applications. For lane assist systems, VPS and a lateral positioning system can augment DGSP in urban areas, providing seamless operation where DGPS accuracy is insufficient for lane keeping. This research focused on designing and building a prototype VPS using existing third party RFID hardware. The hardware was evaluated and characterized to determine if it could be used to create a viable, robust VPS. After the development and characterization of the positioning system, an implementation of a rear-end collision avoidance system was built to demonstrate the use of VPS. Finally, a more sophisticated rear-end collision avoidance system was designed and simulated, after which its implications to the accuracy specifications for VPS were analyzed.Cheng, Pi-Ming; Donath, Max; Gorjestani, Alec; Menon, Arvind; Newstrom, Bryan; Shankwitz, Craig. (2008). Advanced BRT Volume II: Innovative Technologies for Dedicated Roadways. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/96275
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Macroscopic Review of Driver Gap Acceptance and Rejection Behavior at Rural Thru-Stop Intersections in the US - Data Collection Results in Eight States: CICAS-SSA Report #3
No full textCrashes at rural thru-stop intersections arise primarily from a driver attempting to cross or enter the mainline traffic stream after failing to recognize an unsafe gap condition. Because the primary cause of these crashes is not failure to stop, but failure to recognize an unsafe condition, the US DOT FHWA, MnDOT, and the University of Minnesota ITS Institute undertook the CICAS-SSA program. CICAS-SSA uses roadside radar sensors, a computer processor and algorithms to determine unsafe conditions, and an active LED icon based sign to provide timely alerts and warnings which are designed to reduce the frequency of crashes at rural expressway intersections. These rural, thru-stop crashes are problems in many states. In conjunction with the CICAS-SSA program, MnDOT and the University of Minnesota led a nine-state (CA, GA, IA, MI, MN, NC, NH, NV, and WI) pooled fund study whereby driver behavior data at rural thru-stop intersections was collected by the Minnesota Mobile Intersection Surveillance System (MMISS). The ultimate goal of the pooled fund study and the analysis of that data described here, was to identify whether drivers in different regions of the county exhibit different gap acceptance/rejection behavior, and if different
driver behaviors are identified, determine whether they are different enough to inhibit the deployment of a common CICAS-SSA design throughout the US. The analysis of the data indicated that the system can indeed be deployed nationally.Gorjestani, Alec; Menon, Arvind; Cheng, Pi-Ming; Newstrom, Bryan; Shankwitz, Craig; Donath, Max. (2010). Macroscopic Review of Driver Gap Acceptance and Rejection Behavior at Rural Thru-Stop Intersections in the US - Data Collection Results in Eight States: CICAS-SSA Report #3. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/101441
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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