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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.
11

Design of an electric activation system for the smart hybrid tendons crack-closure system in concrete beams

Balzano, B., Sharifi, S., Sweeney, John, Thompson, Glen, de Nardi, C., Jefferson, T. 07 August 2024 (has links)
Yes / This work presents the design of a smart activation system for the crack-closure technology of the Hybrid Tendons. Previous research has demonstrated the effectiveness of this technology in providing a self-repairing mechanism for concrete elements. The Hybrid Tendons are made combining a pre-stressed Kevlar inner core restrained by a Shape Memory Polymer sleeve. To trigger the crack-closing action, the Shape memory potential of the outer sleeve needs to be activated via heating. The work focuses on the design and testing of an electric activation system for the Hybrid Tendons using a system of heating wires. Kanthal wires are chosen for this application and integrated in the manufacturing process of the Hybrid Tendons: the wires are wrapped around each tendon and connected to a power supply. An experimental campaign is conducted to assess the system's capability to activate the Hybrid Tendons and deliver the crack-closing action in concrete beams under constant load. Additionally a numerical model is also developed to offer a sound interpretation of the experimental results. The system is ultimately proven successful in activating the Hybrid Tendons embedded in the concrete, effectively delivering the crack-closing action and boosting the flexural response of the structural element. / UKRI-EPSRC (Grant No. EP/P02081X/1 , Resilient Materials 4 Life, RM4L), Leverhulme Trust ECF-2022-235.
12

Field monitoring and modeling of pavement response and service life consumption due to overweight truck traffic

Oh, Jeong-Ho 15 November 2004 (has links)
A number of pavement structures experience deterioration due to high traffic volume and growing weights. Recently, the Texas Legislatures passed bills allowing trucks of gross vehicle weight (GVW) up to 556 kN routinely to use a route in south Texas along the Mexican border. Thus, there is a need to model pavement responses due to various types of overweight truck traffic (OTT) by taking into account axle loads, configuration, and pavement layer material characterizations in order to provide a guideline to assess the existing pavement performance and expected service life. It is for this purpose that the nonlinear cross-anisotropic pavement analysis finite element program (NCPA) has been developed. Stress dependent and directionally different resilient modulus and Poisson's ratios are incorporated into the finite element formulation to model the pavement response. As a tool to assess the performance of the pavement, the procedure to calculate the overall rutting and the cracked area was included in the formulation Intensive nondestructive testing has been performed to identify the existing pavement test section geometry and layer properties. In addition, a fiber optic based Weigh-in Motion (WIM) sensor was developed and tested. It is expected to be a promising device to monitor traffic by showing a reliable response. Sampled materials from the test section were tested to characterize their stress-dependent, cross-anisotropic and permanent deformation properties. Constitutive models are verified by comparing the predicted displacements with field displacements measured with the Multi-Depth Deflectometer (MDD). The result was that the least error between predicted and measured displacements is generated by the nonlinear cross-anisotropic model. In addition, the cross-anisotropic characteristic of the asphalt concrete material is introduced and evaluated based on the relationship between the backcalculated static and dynamic modulus. This addition improves the accuracy of the assessment of pavement performance with respect to both rutting and fatigue cracking. Charts to evaluate the service life of the existing pavement subjected to OTTs are established in terms of the unit service life consumed due to the rutting and fatigue cracking with the various observed combinations of pavement geometry, traffic load, and material properties.
13

Life cycle cost analysis of pavements : state-of-the-practive /

Guven, Zeynep. January 2006 (has links)
Thesis (M.S.)--Clemson University, 2006. / Includes bibliographical references (p. 133-136). Also available online.
14

MODELLING MSW LEACHATE CHARACTERISTICS AND CLOGGING

Yu, Yan 26 April 2012 (has links)
A numerical model (BioClog) is developed to examine changes in key municipal solid waste (MSW) leachate characteristics and the porosity of porous media (clogging) as the leachate passes through the drainage layer of a leachate collection system (LCS). The model considers multiple-species reactive leachate transport through porous media. It simulates biofilm growth and loss, deposition of suspended particles, and precipitation of minerals on the surface of porous media. It is used to examine the long-term performance of both the granular porous media and nonwoven geotextiles in LCSs. Modelling of laboratory mesocosm cells filled with gravel usually used in landfills and permeated by landfill leachate shows encouraging agreement between the observed and measured effluent chemical oxygen demand (COD) and calcium concentrations as well as the gravel porosity within the saturated drainage layers. Studies of early generation LCSs involving finger (French) drain systems show that the finger drains are not effective at controlling leachate mounding within the landfill and the calculated leachate mound thicknesses agree well with observed field data. A numerical examination of the recent generation of LCSs, comprised of the granular drainage blanket and perforated drainage pipes, shows that an increase in grain size increases the service life and that increasing the spacing between collection pipes (i.e., the drainage path) decreases the service life of LCSs. Filter-separator layers between the waste and granular drainage layers are shown to increase the service life of LCSs. The modelling results indicate that the calculated clog mass within the saturated drainage layer is dominated by the inorganic material and the calculated service life of LCSs is dependent on the leachate strength examined. Finally, a new practical model for estimating the service life of LCSs is developed and calibrated against the data from the BioClog model. The simplified model could be used by the practicing engineers for estimating the service life and optimizing the design of LCSs in MSW landfills. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2012-04-26 14:03:22.666
15

A methodology for probabilistic remaining creep life assessment of gas turbine components

Liu, Zhimin 08 1900 (has links)
No description available.
16

Truck overloading study in developing countries and strategies to minimize its impact

Chan, Ying Chuen (Maple) January 2008 (has links)
Overloading truck traffic is an untenable problem around the world. The occurrence of overloaded truck traffic can be evidence of rapid development of an economy. Most of the developing countries emphasize the development of economy, thus supporting reform of infrastructure is limited. This research investigates the relationship between truck overloading and the condition of road damage. The objective of this research is to determine the amount of economic loss due to overloaded truck traffic is. Axle load will be used to calculate the total ESAL to pavement. This study intends to provide perspective on the relationship between change in axle load due to overloading and the resultant service life of pavement. It can then be used in the estimation of pavement damage in other developing countries facing the problem of truck overloading. In conclusion, economical loss was found, which include reduction of pavement life and increase in maintenance and rehabilitation (M&R) cost. As a result, net present value (NPV) of pavement investment with overloading truck traffic is higher than normal truck traffic.
17

Accelerated ageing tests and long-term prediction models for durability of FRP bars in concrete

Chen, Yi, January 1900 (has links)
Thesis (Ph. D.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains xiii, 201 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 191-201).
18

An Exploratory Examination of the Impact of Web Functionality across the Customer Service Life Cycle

Pearson, Ann M. 01 January 2009 (has links) (PDF)
Using the resource-based view (RBV) of the firm, this research examines how organizations integrate organizational resources with Web technology to implement Web functionalities to support the four stages of the Customer Service Life Cycle (CSLC). This research examines how combinations of Web functionalities impact the relative importance of the stages of the CSLC in determining customer satisfaction. The relative important of the stages of the CSLC varied depending on the product being considered for purchase (textbook, personal computer, and pair of jeans) and the gender of the online customer. Results of six regressions using policy capturing indicate that, overall, customers consider Web functionality support for the pre-purchase stages of the CSLC to be most important, with the requirements stage or acquisition stage consistently being first in importance. Post-purchase support showed increased importance with the purchase of a personal computer and textbook, and with male shoppers. Significant differences were limited with the retirement stage being significantly different from all the other stages in five post hoc tests, and from just the acquisition stage in the jeans test. By considering the products sold online and gender of the targeted online customer, organizations can invest their resources to build Web functionalities that incorporate values, culture, and processes to increase customer satisfaction with the Web site and influence firm performance.
19

Comparison Study Between OSHA Rule of Thumb and Software Model Respirator Cartridge Service Life

HEMPHILL, CELESTE NICOLE 26 September 2008 (has links)
No description available.
20

Prediction of Remaining Service Life of Pavements

Balla, Chaitanya Kumar 10 September 2010 (has links)
No description available.

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