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  • 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.
1

Experimental investigations of anchorage capacity of precast concrete bridge barrier for Performance Level 2

Ngan, Caroline Lai Yung 11 1900 (has links)
In the last twenty years, the design requirements of bridge barriers have changed with the aim of improving the safety of commuters on the bridge. A majority of precast concrete bridge barriers (PCBB) on highway bridges in British Columbia were designed and installed in accordance with the 1988 Canadian Highway Bridge Design Code (CHBDC). To ensure that these barriers comply with the current code requirements, research and testing were deemed obligatory. In particular, the anchorage capacity of the parapet under the CHBDC design load warrants verification. A finite element model of the barrier was developed in ANSYS to study its structural response. Static testing of a set of barriers was carried out at the University of British Columbia to better understand the behaviour of the barrier. The experimental results were used to calibrate and verify the finite element model. Through the finite element model and experimental results, a simpler model has been developed in a formatted spreadsheet environment to allow better estimates of the anchorage capacity of different barrier designs. The model was scaled to a wider use for practicing engineers so to ease and improve the design of anchorages of precast concrete bridge barrier under Performance Level 2 loading in accordance with the Canadian Highway Bridge Design Code.
2

Experimental investigations of anchorage capacity of precast concrete bridge barrier for Performance Level 2

Ngan, Caroline Lai Yung 11 1900 (has links)
In the last twenty years, the design requirements of bridge barriers have changed with the aim of improving the safety of commuters on the bridge. A majority of precast concrete bridge barriers (PCBB) on highway bridges in British Columbia were designed and installed in accordance with the 1988 Canadian Highway Bridge Design Code (CHBDC). To ensure that these barriers comply with the current code requirements, research and testing were deemed obligatory. In particular, the anchorage capacity of the parapet under the CHBDC design load warrants verification. A finite element model of the barrier was developed in ANSYS to study its structural response. Static testing of a set of barriers was carried out at the University of British Columbia to better understand the behaviour of the barrier. The experimental results were used to calibrate and verify the finite element model. Through the finite element model and experimental results, a simpler model has been developed in a formatted spreadsheet environment to allow better estimates of the anchorage capacity of different barrier designs. The model was scaled to a wider use for practicing engineers so to ease and improve the design of anchorages of precast concrete bridge barrier under Performance Level 2 loading in accordance with the Canadian Highway Bridge Design Code.
3

Experimental investigations of anchorage capacity of precast concrete bridge barrier for Performance Level 2

Ngan, Caroline Lai Yung 11 1900 (has links)
In the last twenty years, the design requirements of bridge barriers have changed with the aim of improving the safety of commuters on the bridge. A majority of precast concrete bridge barriers (PCBB) on highway bridges in British Columbia were designed and installed in accordance with the 1988 Canadian Highway Bridge Design Code (CHBDC). To ensure that these barriers comply with the current code requirements, research and testing were deemed obligatory. In particular, the anchorage capacity of the parapet under the CHBDC design load warrants verification. A finite element model of the barrier was developed in ANSYS to study its structural response. Static testing of a set of barriers was carried out at the University of British Columbia to better understand the behaviour of the barrier. The experimental results were used to calibrate and verify the finite element model. Through the finite element model and experimental results, a simpler model has been developed in a formatted spreadsheet environment to allow better estimates of the anchorage capacity of different barrier designs. The model was scaled to a wider use for practicing engineers so to ease and improve the design of anchorages of precast concrete bridge barrier under Performance Level 2 loading in accordance with the Canadian Highway Bridge Design Code. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate
4

The Blood-brain barrier in normal and pathological conditions /

Zhu, Chunni. January 2001 (has links) (PDF)
Thesis (Ph.D.)--University of Adelaide, Dept. of Anatomical Sciences, 2002? / Bibliography: leaves 318-367.
5

Knowledge transfer in project-based environments : The barriers of knowledge transfer

Niu, Bingyu, Yan, Sisi January 2012 (has links)
Background: Nowadays, projects become the common way of working in manycompanies. Knowledge management is important for efficient project management.Knowledge transfer in project-based environments became an attractive and importanttopic for study. Various barriers and challenges will appear during the process ofknowledge transfer in projects. Lots of authors thought the barriers of knowledgetransfer in project are negative, while others mentioned that some barriers may havepositive aspects. We called these two kinds of barriers “positive barriers” and“negative barriers” in this thesis. Purpose: The purpose of this thesis is to understand knowledge transfer inproject-based environments. Specifically, we aim to explain that barriers ofknowledge transfer in projects can be both negative and positive. Method: Due to the special time period and activity limitation, we chose case studyto gain the empirical data. When choosing the sample, we used the conveniencesampling. The sample chosen is a project team in Ericsson of Linköping. The projectmanager we interviewed has worked in Ericsson since 2004 and with his presentproject team for four years. He has already done more than fifteen projects, so he hasenough experience in projects for our study. We combined both inductive anddeductive approach strategies to analyze our thesis. Result: This thesis has answered the questions in the part of specified questions andreached the thesis purpose. It has explained the notion of knowledge transfer inprojects and its related barriers. It interprets how both negative and positive barriersaffect knowledge transfer. Furthermore, this thesis points out some suggestions forimproving positive barriers and reducing negative barriers.
6

A DERIVATION OF AN EMPIRICAL EQUATION FOR ESTIMATING THE ACOUSTICAL SHADOW ZONE LENGTH OF ROADWAY NOISE BARRIERS

Arner, Wayne 11 January 2007 (has links)
The objective of this research was to derive an empirical equation that estimates the acoustical shadow zone length (SZL) of roadway noise barriers. The acoustical shadow zone is the area behind a noise barrier of reduced sound levels, generally to some stated level at or near background. The ability to predict the SZL can be used as a method to evaluate the performance, and possibly the design, of roadway noise barriers. The current federally required roadway noise model is the Federal Highway Administration (FHWA) Traffic Noise Model (TNM). TNM uses insertion loss (IL) to evaluate the effectiveness of a barrier. Insertion loss is the difference in sound level between the "no barrier" and the "with barrier" case. One major limitation with TNM is that the reported IL does not take into account how background noise levels influence the mitigated sound levels. Background noise can be defined as the noise present at a barrier location in the absence of roadway noise. The shadow zone represents a region behind the noise barrier where the barrier is effective at reducing noise levels and takes into account how background noise affects the IL and thus the SZL. The inclusion of background noise becomes significant in evaluating barrier effectiveness because as the distance from the barrier increases, background noise begins to overtake roadway noise as the dominate noise source. The derivation of the empirical equation began by collecting in-situ noise measurements at 18 noise barrier locations across Florida. The measured noise data was supplemented by noise data obtained from computer modeling. After a sufficient quantity of measured and modeled IL data was obtained, a contour of equal IL (IL = 5 dB) was plotted for each barrier location. The area defined by the contour is called the shadow zone. All the SZLs were statistically compared to several variables that were expected to influence it. Regression modeling showed that the background noise level, noise barrier height, the distance from the roadway to the noise barrier, and percent of heavy truck traffic volume were statistically significant as useful predictors of SZL. Two empirical equations were derived, one from linear regression and one from polynomial regression, and are referred to as the Shadow Zone Equations. / M.S.Env.E. / Department of Civil and Environmental Engineering / Engineering and Computer Science / Environmental Engineering
7

Anti-capillary barrier performance of wicking geotextiles

Azevedo, Marcelo Moraes de 05 November 2012 (has links)
A capillary barrier develops and restricts water flow when two porous materials with dissimilar pore structures (e.g., a coarse-grained soil overlain by a fine-grained soil) are in contact with one another. This is due to a difference in the unsaturated hydraulic conductivity of the two materials at a given suction. Geotextiles are utilized in a variety of civil engineering applications and have a pore structure similar to that of a coarse-grained soil. This can be problematic in unsaturated soil as the capillary barrier caused by the geotextile may instigate undesirable moisture buildup in the overlying soil and undermine any benefit provided by the geotextile. Various versions of a new geotextile have been manufactured to help dissipate a capillary barrier by "wicking" or laterally draining excess moisture away from the soil. Additionally, nonwoven blends of the unique wicking fiber combined with standard polymeric fibers are tested to assess their ability to minimize the development of a geotextile capillary barrier and not cause additional moisture accumulation in the first place. The unsaturated properties of both woven and nonwoven configurations of these wicking geotextiles were investigated as part of a comprehensive an experimental testing program. The testing program includes small soil column infiltration tests to assess geotextile capillary barrier performance with moisture monitored by time domain reflectometers and capacitance probes. Also, modified hanging column tests were conducted to define the hydraulic properties of the geotextiles in the form of water retention curves. Finally, a microscopy study, involving both optical and scanning electron microscopes, was conducted to observe the wicking behavior of the geotextiles at a micro-scale level. Test results illustrate the enhanced lateral drainage and reduced moisture accumulation of the wicking geotextiles when compared to regular geotextiles. Additionally, the woven version of the wicking geotextile has the potential to perform the functions of separation, filtration, protection, reinforcement, and drainage. All of these functions in a single geosynthetic product could lead to significant cost savings compared to the use of separate products to perform each one of the various functions. / text
8

Assessing the disability inclusiveness of buildings

Lau, Wai-kin, 劉偉健 January 2014 (has links)
With rights to access now become basic human rights, it demands a tool for building disability inclusiveness assessment to tell how far we have gone to include persons with disabilities (PWDs) in buildings. Calling for more researches in disability inclusive facilities and inclusive education in various international conventions and statements such as the UN Convention on the Rights of Persons with Disabilities (2006) and the UNESCO Salamanca Statement (1994), the Physical Disability Inclusion Sub-score (PDIS) and the Visual Impairment Inclusion Sub-score (VIIS) as simple, quantitative and more objective tools for assessing higher education buildings were developed here. Other than that whether building professionals have knowledge of the way PWDs access and use buildings were at the same time examined. This study consists of four parts with (1) conception, (2) the PDIS and the VIIS for assessing the disability inclusiveness of buildings, (3) main survey and (4) conclusion. By way of literature review, the PDIS and the VIIS frameworks were constructed and they were fine-tuned with inputs from building professionals and users with impairments in the pilot phase. NSFDSS but not the far more popular AHP was applied to weight the elements under the PDIS and the VIIS for both credibility and practicality reasons. In all, between March and July 2012, 20 building professionals, 22 persons with physical disability and 21 persons with visual impairment were surveyed. The PDIS and the VIIS then developed were much simplified with around 200 items under about 20 categories. Design was weighed by all to be more important than Management. Following that 48 higher education buildings from four universities in Hong Kong were assessed in March to September 2013. The dispersal of the PDIS and the VIIS were found largely due to Design rather than Management. In the disability inclusion performance of different categories, Operations and Maintenance, and Management Approaches were respectively the best and the least well performed categories, and Vertical Circulation and Entrance were the more disability inclusive Design categories. As for hypothesis testing, 13 working hypotheses were developed from 4 main hypotheses. By Spearman’s rank correlation test or the t-test, it was found that building professionals and both persons with physical disability and persons with visual impairment did not weigh the elements under the PDIS and the VIIS differently, and the mean values of the standard deviation of the weightings given by users with impairments were not greater than those given by building professionals. It is evidenced that building professionals somehow have knowledge of the way the physically impaired and the visually impaired access and use buildings, and impaired users are not biased on their experience. Having the PDIS and the VIIS developed, it is in pole position to adjust and apply them to study other buildings such as health care facilities and office buildings. Towards a more progressively aggressive step is to make changes to them to examine the more complex issue of ageing friendliness of buildings for the grey population following WHO Age-friendly Environments Programme. / published_or_final_version / Real Estate and Construction / Doctoral / Doctor of Philosophy
9

Measurement of the airborne sound insulation of traffic noise barriers using impulse response techniques

Bull, John Ivan January 2014 (has links)
This research thesis involves the measurement of the airborne sound insulation of road traffic noise barriers, with the goal of gaining a more in depth understanding of the factors that influence noise barrier performance. A measurement system is developed, based on EN 1793-6:2012, to quantify the airborne sound insulation of a noise barrier in situ. Validation testing is performed to ensure that the system meets the requirements of EN 1793-6:2012. MATLAB code is developed, incorporating all of the signal processing tasks into a single graphical user interface. The measurement system is then used to measure the airborne sound insulation of eight existing traffic noise barriers located around Auckland, New Zealand. The results from the Auckland field tests show that consistent single number ratings of airborne sound insulation can be achieved on different samples of the same noise barrier. The presence of air gaps and hidden defects will degrade the acoustic performance of a noise barrier, most significantly at the high frequencies. The comparison of single number ratings calculated with differing measurement frequency ranges is discussed, and some comments are made on the measurement standard itself.
10

Running away from and coming into the building: analysis of the ordinance relating to mean of escape andbarrier free access and understanding the conservation issues involved

Cheung, Wing-yee, Megdalen, 張穎儀 January 2007 (has links)
published_or_final_version / Conservation / Master / Master of Science in Conservation

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