• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1050
  • 413
  • 404
  • 156
  • 150
  • 49
  • 39
  • 39
  • 29
  • 26
  • 17
  • 14
  • 10
  • 10
  • 10
  • Tagged with
  • 2821
  • 452
  • 432
  • 366
  • 296
  • 223
  • 175
  • 172
  • 165
  • 150
  • 141
  • 140
  • 140
  • 138
  • 129
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
411

Functional Properties of Concrete Roads - Development of an Optimisation Model and Studies on Road Lighting Design and Joint Performance

Löfsjögård, Malin January 2003 (has links)
The roads constitute a major part of the nation’sinfrastructure. For the society and the individuals it isimportant with a well functioning road network. To sustain theimpact from traffic intensity and heavy loads durable pavementsare demanded. Concrete pavements for roads with high trafficintensity and heavy loads are common in the USA and in severalEuropean countries. In Sweden, less than 1 % of the roadnetwork consists of concrete roads. The research about concrete road pavements has been focusingon development of design methods and studies of surfaceproperties like friction, longitudinal evenness, wearresistance and noise. To increase the knowledge and use ofconcrete roads there is a need to optimise the differentfunctional properties with regard to each other and to socialfactors. The objective of this doctoral thesis is to survey, analyseand quantify relationships between functional properties ofconcrete roads and social factors such as environmental impact,traffic and user safety, riding comfort and economicconsiderations (costs). The goal is to develop a model that canbe used as an instrument for optimising the concrete roaddesign. This thesis describes a thorough literature investigation,special studies on road lighting design of concrete pavements,laboratory investigations about saw-cutting times for jointsand bonding properties of dowels and development of anoptimisation model. The literature investigation has resultedin compiled knowledge on functional properties of concreteroads and their relationships with social factors. A compiledanalysis has also been performed from follow-ups of the fourconcrete roads constructed in Sweden in the 1990s. From thespecial study on road lighting design, proposals are made forusing new values for brightness and specularity and changingthe classification of wet concrete pavements. Theinvestigations of joint performance have given recommendationsfor the earliest saw-cutting time for joints in concrete roads.An optimisation model is proposed, and presently parts of themodel can be used for economic comparisons between differentalternatives. The proposed model needs further research regardingvaluation of the relationships before the model can be used asa total model. Other areas interesting for further researchare: road lighting design and especially wet pavements, upperbound of sawcutting time for joints and further analysis ofdowel performance.
412

Emerging opportunities in the Vietnamese Electronic Road Toll market for Company X

Ferdinand, Andreas January 2009 (has links)
Aim: The purpose of this study is to explore the Vietnamese market for Electronic Road Tolls. Company X is a world wide supplier of electronic toll systems. They are focusing on systems that will reduce traffic congestion in cities or congestion created by road charge toll systems. Company X has been active in the South East Asia for over 10 years. Now they want to explore new markets in this region. The company is interested in developing countries where road infrastructure is expanding. Since Vietnam is one of the fastest growing economies in Asia Company X is interested in if it is a market they should enter.   Research questions:  Should Company X enter the Vietnamese market? If yes, which entry strategy should be used entering this market?   Method: To analyze Company X’s internal and external environment I have used different theoretical methods, PEST analysis, Micro / Macro environmental analysis and with the SWOT framework I have summarized recommendations based on the facts I have gathered. I have also investigated different entry strategies to see what is most suitable for a Company X. I have collected data via interviews, literature and internet sources.   Result & Conclusions: Short term Company X has the opportunity to come in with their products into Vietnam with a co-operation with Competitor A. They will set up a test system at one toll plaza between the airport and Hanoi with two lane dedicated for EFC and Company X is their first choice if they are competitive. This will give them the opportunity to be first on this market to implement microwave equipment in Vietnam and an opportunity to set the standard in the country for the future.  Suggestions for future research: The empirical data in this thesis is mainly gathered from secondary sources. The information would have been more accurate with more primary data.   Contribution of the thesis: This thesis shows that large investments in road infrastructure are coming up in Vietnam. This thesis also shows that currently there is low activity from competitors using the same technology and this was not previously known by Company X.
413

A House is Not (Necessarily) a Home: Nomads, American Truck Drivers, and the Creation and Conception of Home

Marshall, Brooke 11 May 2013 (has links)
What is home? Is it simply a place, or is it something more than that? What is the nature of home for truck drivers? Where does it occur, and how do they create and conceptualize it? I examine the literature on home, concluding that home is not a place but rather a relationship that occurs between an individual and a place. I then draw upon autoethnographic research to communicate how truck drivers conceptualize and create home.
414

A Method to Quantify Road Safety Audit Data and Results

Jones, Joshua Reid 01 May 2013 (has links)
The research presented in this thesis is the result of field data collection conducted by the Utah Local Technical Assistance Program (Utah LTAP) in conjunction with the Utah Department of Transportation. The first step of the research was data collection from 18 road safety audits conducted throughout the state of Utah. These Road Safety Audits (RSA's) provided a wide variety of data that was used for the validation of the road safety audit quantification methodology. The purpose of this research is to provide quantification to the RSA process that will increase the benefits gained from implementing the RSA recommendations. Benefits derived from the implementation of RSA recommendations were found by assessing the change of risk from before and after safety improvements. The RSA quantification tool was developed to analyze projects in both urban and rural settings. The implementation of the RSA tool will help practitioners show the benefits that can be gained from the safety recommendations and help decision makers in allocating funds to the areas that pose the most risk. The tool will show the difference in risk that the improvements make and the cost effectiveness of different project alternatives.
415

The Spatial Ecology of Eastern Hognose Snakes (Heterodon platirhinos): Habitat Selection, Home Range Size, and the Effect of Roads on Movement Patterns

Robson, Laura E 30 November 2011 (has links)
Habitat loss is the greatest contributor to the decline of species globally and thus understanding habitat use and the consequences fragmentation has on biodiversity is a fundamental step towards management and recovery. I conducted a radio-telemetry study to examine the spatial ecology and the effects of roads on Eastern Hognose Snakes (Heterodon platirhinos), a species at risk, in the Long Point Region of Ontario, Canada. I tested habitat selection at multiple spatial scales and I found that within the home range, snakes avoided agricultural land and selected open sand barrens, particularly for nesting. At the local scale, snakes avoided mature overstory trees and used younger patches of forest. Used locations had more woody debris, logs and low-vegetative coverage than locations selected at random. Eastern Hognose Snakes also showed avoidance of paved road crossings in their seasonal movements, but readily crossed unpaved roads. Management efforts for this species at risk should be placed on the conservation of sand barrens and on the construction of road underpasses to prevent genetic isolation of populations.
416

The Spatial Ecology of Eastern Hognose Snakes (Heterodon platirhinos): Habitat Selection, Home Range Size, and the Effect of Roads on Movement Patterns

Robson, Laura E 30 November 2011 (has links)
Habitat loss is the greatest contributor to the decline of species globally and thus understanding habitat use and the consequences fragmentation has on biodiversity is a fundamental step towards management and recovery. I conducted a radio-telemetry study to examine the spatial ecology and the effects of roads on Eastern Hognose Snakes (Heterodon platirhinos), a species at risk, in the Long Point Region of Ontario, Canada. I tested habitat selection at multiple spatial scales and I found that within the home range, snakes avoided agricultural land and selected open sand barrens, particularly for nesting. At the local scale, snakes avoided mature overstory trees and used younger patches of forest. Used locations had more woody debris, logs and low-vegetative coverage than locations selected at random. Eastern Hognose Snakes also showed avoidance of paved road crossings in their seasonal movements, but readily crossed unpaved roads. Management efforts for this species at risk should be placed on the conservation of sand barrens and on the construction of road underpasses to prevent genetic isolation of populations.
417

The influence of winter weather on high-crash days in Southern Ontario

Afrin, Sadia 22 August 2013 (has links)
Traffic crashes tend to occur at relatively greater frequencies at particular locations, at particular time periods, and for particular subsets of drivers and vehicles. It is well recognized among the road safety community that crash-risk is highly elevated when inclement weather conditions occur in the winter. To present, most of the road safety studies focus on event-based analysis or seasonal analysis and give little attention to explore high-risk conditions at the daily temporal scale. The purpose of the study is to advance our understanding of high-risk crash conditions at the daily level and their occurrences in Southern Ontario, Canada. The study explores different definitions of high-crash days, and quantifies the influences of weather conditions, risk exposure, months and timing of precipitation on the likelihood of a high-crash day occurring using binary logistic regression model. Additionally, an approach for estimating the relative risk exposure using available traffic count data has also been developed. The results of the study show a small proportion of high-crash days are responsible for a considerable amount of traffic crashes during the winter. The risk of traffic crash is twice as high on high-crash days in comparison to non-high-crash days. The modeling approach well-fits the data and shows that winter weather conditions have significant influence on high-crash days with results being mostly consistent across the four study areas, Toronto, the Area Surrounding Toronto, London and the Area Surrounding London. Low temperature, heavy snowfalls, high wind speeds, high traffic volumes, early winter months, occurrence of precipitation in both morning and evening increase the odds of high-crash days to a large extent. The results of study could help to pre-schedule traffic operation and enforcement, to effectively distribute road safety resources and personnel, and to create situational awareness among road users and other stakeholders.
418

A Mathematical Model for Winter Maintenance Operations Management

Trudel, Mathieu January 2005 (has links)
Scheduling of winter maintenance operations such as plowing or salting is a difficult and complex problem. Proper selection and timing of such operations is critical to their effectiveness, however scheduling decisions must often be made with strict time and resource limitations imposed upon them. A decision support system which analyses current road conditions and makes scheduling suggestions based on them would be a valuable step toward improving the quality of treatment, while simultaneously reducing the burden of scheduling on maintenance managers. This thesis proposes a real-time scheduling model based on an Operations Research framework that can be used by maintenance managers to develop and evaluate alternative resources allocation plans for winter road maintenance operations. The scheduling model is implemented as an Integer Linear Program and is solved using off-the-shelf software packages. The scheduling model takes into account a wide range of road and weather condition factors such as road network topology, road class, weather forecasts, and contractual service levels, and produces a vehicle dispatch schedule that is optimal with respect to operating costs and quality of service. A number of heuristics are also explored to aid in efficient approximations to this problem.
419

Road Roughness Etimation Using Available Vehicle Sensors

Lundström, Johan January 2009 (has links)
Road conditions affect fuel efficiency and vehicle fatigue when driving heavy trucks. Information about traveled road conditions enable optimization of chassis configuration when driving, and logging of vehicle stress. Previous work on this topic focus mainly on tuning of active suspension parameters in the car industry. One conceivable application for heavy trucks is implementation of active chassis level control based on road conditions, with possible improvements in driving economy as result. Another is logging of usage conditions which helps explain vehicle faults caused by abnormal wear. This work examines the possibilities to use already on vehicle sensors for road roughness estimation. It also investigates what requirements existing signals must fulfill to ensure reliable estimates. Two methods for road roughness estimation are proposed using rear axle level sensor and a simple linear suspension system model.
420

A Contour-based Separation of VerticallyAttached Traffic Signs

Zhao, Ping January 2007 (has links)
This report presents an algorithm for locating the cut points for and separatingvertically attached traffic signs in Sweden. This algorithm provides severaladvanced digital image processing features: binary image which representsvisual object and its complex rectangle background with number one and zerorespectively, improved cross correlation which shows the similarity of 2Dobjects and filters traffic sign candidates, simplified shape decompositionwhich smoothes contour of visual object iteratively in order to reduce whitenoises, flipping point detection which locates black noises candidates, chasmfilling algorithm which eliminates black noises, determines the final cut pointsand separates originally attached traffic signs into individual ones. At each step,the mediate results as well as the efficiency in practice would be presented toshow the advantages and disadvantages of the developed algorithm. Thisreport concentrates on contour-based recognition of Swedish traffic signs. Thegeneral shapes cover upward triangle, downward triangle, circle, rectangle andoctagon. At last, a demonstration program would be presented to show howthe algorithm works in real-time environment.

Page generated in 0.068 seconds