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You searched for subject:(Speed profile model). Showing records 1 – 2 of 2 total matches.

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University of Kansas

1. Li, Yue. Analyzing Drivers' Responses to Portable Changeable Message Signs in Rural Highway Work Zones.

Degree: PhD, Civil, Environmental, & Architectural Engineering, 2011, University of Kansas

The number of work zones has been increasing in the highway system of the United States because of rising needs in highway construction and maintenance. Highway work zones disrupt normal traffic flow and create safety problems. To improve safety by reducing the risk of vehicle crashes, temporary traffic control devices have been developed and implemented in work zones. A Portable Changeable Message Sign (PCMS), one of the temporary traffic control devices, is capable of displaying a variety of messages to inform motorists of unusual driving conditions in highway work zones. To better utilize a PCMS in work zones, there is a need to investigate the effectiveness of a PCMS and determine the optimal deployment location of a PCMS in the work zones. The primary goals of this research project were to determine the effectiveness of a PCMS on reducing vehicle speeds and the optimal deployment location of a PCMS in the upstream of one-lane two-way rural highway work zones using the field experiments and survey methods. A slower vehicular speed allows for greater reaction time to avoid crashes, and potentially creates a safer environment for drivers and workers in the work zones. Vehicles were divided into two categories, namely passenger cars and trucks. To accomplish the goals of the research project, the following main tasks were performed: 1) determining the effectiveness of a PCMS on reducing passenger cars and trucks speeds under three conditions (PCMS On, Off, and Absent) using field experiments, 2) developing vehicle speed profile models, 3) using the speed profile models and measured mean speeds to determine the optimal deployment range of a PCMS in the upstream of work zones, 4) investigating drivers' reactions after seeing a PCMS using the survey method, and 5) comparing the speed reductions of passenger cars and trucks to determine if a PCMS could be utilized to reduce the risks of truck-related crashes in one-lane two-way rural highway work zones. Utilizing the findings of this research project, traffic engineers will be able to determine if, where, and how a PCMS needs to be deployed in one-lane two-way rural highway work zones to mitigate vehicle crash risks. As a result, the safety of work zones will be improved and resources will be better utilized. Advisors/Committee Members: Bai, Yong (advisor), Hu, Yaozhong (cmtemember), Mulinazzi, Thomas E. (cmtemember), Schrock, Steven (cmtemember), Atchley, Paul (cmtemember).

Subjects/Keywords: Transportation; Pcms; Speed profile model; Truck; Work zone

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Li, Y. (2011). Analyzing Drivers' Responses to Portable Changeable Message Signs in Rural Highway Work Zones. (Doctoral Dissertation). University of Kansas. Retrieved from http://hdl.handle.net/1808/7654

Chicago Manual of Style (16th Edition):

Li, Yue. “Analyzing Drivers' Responses to Portable Changeable Message Signs in Rural Highway Work Zones.” 2011. Doctoral Dissertation, University of Kansas. Accessed October 23, 2017. http://hdl.handle.net/1808/7654.

MLA Handbook (7th Edition):

Li, Yue. “Analyzing Drivers' Responses to Portable Changeable Message Signs in Rural Highway Work Zones.” 2011. Web. 23 Oct 2017.

Vancouver:

Li Y. Analyzing Drivers' Responses to Portable Changeable Message Signs in Rural Highway Work Zones. [Internet] [Doctoral dissertation]. University of Kansas; 2011. [cited 2017 Oct 23]. Available from: http://hdl.handle.net/1808/7654.

Council of Science Editors:

Li Y. Analyzing Drivers' Responses to Portable Changeable Message Signs in Rural Highway Work Zones. [Doctoral Dissertation]. University of Kansas; 2011. Available from: http://hdl.handle.net/1808/7654


NSYSU

2. Ding, Jing-zhong. Effects of sound speed variation and measurement errors on the positioning of a seafloor transponder.

Degree: Master, IAMPUT, 2013, NSYSU

Plate motions over the past few million years have averaged 110 centimeters per year. To monitor such slight deformations in the crust by the GPS/Acoustic geodesy, the accuracy on the order of a few centimeters in positioning seafloor transponders is required. Temporal and spatial variability of sound speed in the water column, however, as well as the measurement error of sound speed, is a main limiting factor in the production of accurate acoustic ranging even though frequent conductivity-temperature-depth (CTD) casts are made. Therefore, in this study, various geometrical options for acoustic ranging are designed in the numerical simulation of GPS/Acoustic geodesy and the effects of various sound-speed measurement errors on the accuracy of transponder positioning are evaluated. The simulation results show that observing slant-range measurements symmetrically around the transponder can nullify sound-speed errors in the horizontal but not vertical positioning of a seafloor transponder. Sound-speed errors produce the vertical positioning error although the slant-range observations are well geometrically balanced. For reducing the effect of sound-speed variation on the precision of GPS/Acoustic seafloor geodesy, this study proposes two synthetic sound-speed profiles of the water column, one linear and the other bilinear, to approximate acoustic travel-time measurements. The approximating sound-speed profile is used in combination with the tomographic estimation in GPS/Acoustic geodesy to estimate the sound speed variation, such that the effect of sound speed variation on the accuracy of transponder positioning is reduced. The performance of the two synthetic models is evaluated for different types of CTD-derived sound-speed profiles and for the acoustic ranging observations collected from a field GPS/Acoustic survey. The evaluation results demonstrate that both the linear and bilinear models can effectively reduce the effect of sound-speed variation on the precision of GPS/Acoustic positioning. Advisors/Committee Members: Chau-Chang Wang (chair), Chi-Cheng Cheng (chair), Hsin-Hung Chen (committee member).

Subjects/Keywords: bilinear model; linear model; sound-speed profile; positioning; seafloor transponder; GPS/Acoustic geodesy

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Ding, J. (2013). Effects of sound speed variation and measurement errors on the positioning of a seafloor transponder. (Thesis). NSYSU. Retrieved from http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0705113-104933

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Ding, Jing-zhong. “Effects of sound speed variation and measurement errors on the positioning of a seafloor transponder.” 2013. Thesis, NSYSU. Accessed October 23, 2017. http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0705113-104933.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Ding, Jing-zhong. “Effects of sound speed variation and measurement errors on the positioning of a seafloor transponder.” 2013. Web. 23 Oct 2017.

Vancouver:

Ding J. Effects of sound speed variation and measurement errors on the positioning of a seafloor transponder. [Internet] [Thesis]. NSYSU; 2013. [cited 2017 Oct 23]. Available from: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0705113-104933.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Ding J. Effects of sound speed variation and measurement errors on the positioning of a seafloor transponder. [Thesis]. NSYSU; 2013. Available from: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0705113-104933

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.