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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

Performance of Adhesive and Cementitious Anchorage Systems

Mendoza, Mirna 11 July 2017 (has links)
Post-installed anchoring systems are used extensively in Massachusetts Department of Transportation (MassDOT) projects due their ease of attachment to existing structures. However, recommendations on materials from various manufacturers are currently lacking for certain situations such as long-term tension loading. The purpose of the investigation presented in this thesis was to provide guidance on the use of anchoring systems to MassDOT. This research project evaluated the behavior of adhesive and cementitious bonded anchoring systems per the Stress-versus-Time-to-Failure approach found in the provisional standard AASHTO TP-84 in order to provide recommendations pertaining to the test method. Supplemental short-term anchor pullout tests were conducted using the best performing materials as evaluated by AASHTO TP-84 to study the effects of certain in-service and installation parameters on bond strength. The parameters studied included installation direction and extreme in-service temperatures. Polymer characterization testing of adhesive products were also conducted in order to comment on technique usefulness for field quality assurance/quality control of field installed bonded anchor materials.
2

Electrical energy analysis in nine countries of Europe, with focus on wind power and other renewable energy sources

Ghanian, Nariman, Farhang Esfahani, William Mohammad, Hassan, Muhammad Touqeer Ul January 2015 (has links)
This thesis has been written for the Bachelor degree in Electrical Engineering held at Blekinge Tekniska Högskola Karlskrona, Sweden. The basis of this thesis is a statistical analysis of the electrical energy situation with emphasis on contribution of wind power and other renewable energy in electricity production in the European area and key countries.   The main parameters, which considered in this thesis are electricity production and consumption, installed capacity trends and also the operation of renewable sources, especially wind power in gross electricity generation. Meanwhile, the whole date and materials are based on real values and investigated from the latest publications of governments and energy agencies of European union and key countries.   The target of European renewable energy is that the member countries must achieve at least 20 percent of final energy consumption from renewable energy by 2020. Germany, United Kingdom, Spain and France and Portugal are members of the highest consumers of electricity in the Europe and still the main source of electrical production in these countries are fossil fuels, the main challenge is that they should start to shutting down the traditional power plant and improve the infrastructure for installing the renewable electrical capacity instead.   According to the statistics, many of the European countries such as United Kingdom, Germany, Spain, Denmark and Sweden have started up to use the renewable energy to produce the electrical energy, but their governments have special keen eye for investment in the wind energy sector. Wind power grew sharply during the past decades in Europe and becoming vital every coming day in comparison to other renewable energy, since the low cost of electricity can be granted through a small investment and relies on the wind blowing compared to the conventional electricity generation sources. The diagrams demonstrate the wind power has a main portion to producing the electrical energy and every year a considerable amount of installed capacity is added to the total electrical grid.   In addition, the expansion of renewable energy  to achieve the high percent of electrical production requires  the improvement of  infrastructure such as ecological research and high coordination between different organizations. Also, the electrical generation cannot be constant, and in winter the overall consumption and demand for electricity increases all over Europe. The exploitation of some renewable sources such as solar and wind power for electrical production can have fluctuation due to the weather condition and wind speed, which can affect the overall generation to the electrical grid.   Therefore, the balancing of several renewable sources in different seasons,  needs the unique power management for reliable electrical production. In this trend, Norway is a successful country in Europe that uses over 90 percent of  renewable sources for total electrical generation. The thesis has covered these challenges and how they are overcoming these issues.
3

The Research of Standards Competition of Developing Countries

Chan, Kai-Ru 10 February 2006 (has links)
The standard competition of system proucts has been an important issue from 1950s till today, such as the competitiom of Wireless Lan security protocol WAPI¡BDVD palyer standard and the competiton of TD-SCDMA of 3G system in telecommunication industry. The situation is becoming more and more complicated because of more integration of information and technological products.Recent years, Mainland China as a developing nation try to develop a new standard strategy model and to make the industrial standards belong to China. This paper discovers the major key factors that affect the abilities to join the standard competiton of developing countries. This paper discusses major standard competition related papers and find out five key factors that affect the abilities to join the standard competiton of developing countries: Technological Innovation abilities, entry timing, complementary products network, products installed base and government supporting. Use these five factors to analyze four important China cases od standard competiton.
4

Evaluation of SiteManager as a Tool to Collect Performance Time Data

Rich, Daniel William 11 September 2006 (has links)
This work evaluates SiteManager, the construction documentation system used by VDOT, as a tool for collecting the daily installed quantity and active crew days necessary to populate the operations level of the database. This evaluation first sought to determine if SiteManager was a feasible option for collecting performance data. This was done by establishing data collection methods to enable SiteManager to have the ability to collect performance data, implementing the methods on select projects, resolving issues, and developing recommendations to cause SiteManager to be a more practical option. Secondly, a statistical analysis was performed to determine if the data collected from SiteManager was reasonably accurate. Thirdly, the technical issues of transferring performance data from SiteManager into the performance time database were resolved. It was found SiteManager could not be used in its current format to collect performance data and some modifications are required. / Master of Science
5

A COTS and Standards Based Solution to Weapons System Integration

Scardello, Michael A., Packham, William R., Diehl, Michael 10 1900 (has links)
ITC/USA 2009 Conference Proceedings / The Forty-Fifth Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2009 / Riviera Hotel & Convention Center, Las Vegas, Nevada / The Weapons System Test and Integration Laboratory (WSTIL) at the U.S. Army Yuma Proving Ground (YPG) will provide a new capability for ground based testing in this arena. Current and near term YPG scheduled test programs will benefit tremendously from this enhanced ground test capability provided by the Weapons STIL. The Weapons STIL's design goals center on the implementation of an automated mechanism for testing the weapon systems and sensors that are currently the responsibility of the YPG facility. To meet the Army's weapons test needs the Weapons STIL incorporates various levels of digital stimulation, human-in-the-loop, hardware-in-the-loop, and installed system test facility (ISTF) techniques to maximize ground testing in order to focus and optimize subsequent open air flight testing. This paper describes this work in progress.
6

VOLUMETRIC 3D VISUALIZATION OF TEST AND EVALUATION OPERATIONS

Briggs, James R., Deis, Michael R., Geng, Jason 10 1900 (has links)
International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Time-Space-Position-Information (TSPI) visualization systems used today at the Air Force Flight Test Center (AFFTC) and simulation visualization tools used at the Air Armament Center (AAC) utilize two-dimensional (2D) display systems for both real-time and post-mission data analysis. Examples are monitors and large screen projection systems. Some TSPI visualization systems generate three-dimensional (3D) data as output, but the 3D data is translated so that it is compatible with 2D display systems. Currently, 3D volumetric display systems are being utilized by the Federal Aviation Administration (FAA) for monitoring air traffic in 3D without 3D goggles. The aircraft’s position information is derived from radar and fed to a volumetric display. The AFFTC and AAC need a similar system for Open Air Range testing utilizing the Global Positioning System (GPS) as the source of position information and Installed Systems Testing utilizing 6 Degree of Freedom (DOF) flight simulation data as the source of position information. This system should be capable of displaying realistic terrain structures, vehicle models and physical test configurations along with text data overlays. The ability to display the mission in real-time on a volumetric 3D display makes it possible for test engineers to observe resource utilization continuously as the mission develops. Quicker turn-around times in the decision process will lead to more efficient use of limited test resources and will increase the information content of the data being collected.
7

Pullout Strength of Epoxy Anchors Installed Underwater

Blanchette, Jeffrey Lee 01 December 2012 (has links)
This work presents the development of a test program and the results from the final round of testing to better understand the effect a submerged anchor installation has on the pullout strength of epoxy anchors. Two different epoxies were tested at embedment depths of two, four, and six bar diameters. These tests utilized three distinct installation procedures under dry and submerged conditions. The testing program occurred over five phases, with the final round used in analysis consisting of 24 anchor pullout tests. These tests showed that the presence of water did not have an effect on the epoxy bond when anchor holes were cleaned dry and installed underwater, but it did have a significant impact on the ability to consistently clean each anchor when it was submerged.
8

Creep Behaviour of Post-Installed Adhesive Anchors under Various Sustained Load Levels and Environmental Exposures

El Menoufy, Adham Mohamed 08 1900 (has links)
This thesis describes an experimental study on the long-term creep behaviour of adhesive anchors under sustained tensile loads in combination with different environmental exposures. A comprehensive background and literature review is presented, focusing on various bond stress models for adhesive anchors, factors affecting their bond behavior, and an overview of available testing standards and evaluation criteria. The experimental program comprises of 82 test specimens. The specimens consist of a cylindrical shaped concrete block of 300 mm (12 inch) in diameter and 200mm (8 inch) in depth, with 15M (No. 5) deformed steel bar post-installed to an embedment depth of six times the bar diameter or 125mm (5 inch). Three types of adhesives were used for anchor installation: Type-A a fast setting two component methyl methacrylate adhesive, Type-B a fast setting two part epoxy adhesive, and Type-C a standard set two part epoxy adhesive. The study is divided into four phases. Phase I consists of 27 static pullout tests to determine the yield strength (fy) and the maximum tensile capacity of each anchor system under three exposure conditions. Phase II and Phase III consist of 36 specimens tested under sustained load levels of 40%fy (32kN) and 60%fy (48kN)under normal laboratory conditions (room temperature) and moisture exposure, respectively. Phase IV consists of 9 specimens tested under sustained load with a load level of 40%fy (32kN) with exposure to freeze/thaw cycling. All sustained load tests lasted for a period of at least 90 days. The results of the static pullout testing showed that specimens with epoxy based adhesive exhibited stronger bond strength, forcing the anchor to fail by rupture prior to bond failure. Under sustained load testing, specimens with standard set epoxy based adhesive showed insignificant creep displacement under room conditions, however, when exposed to moisture noticeable creep displacements were recorded. Specimens with both fast setting epoxy and methyl methacrylate based adhesives showed higher creep displacements under environmental exposure (moisture, freeze/thaw) versus those kept at room temperature. Displacement data from creep testing were analysed and projected over a service life span of 50 years for room temperature exposure, and for 10 years for moisture and freeze/thaw exposures. Based on the analysis results, the service life of different anchor systems was estimated. An integrated qualification and testing protocol is proposed for the creep behavior of adhesive anchors under various environmental exposures.
9

Tensile Behavior Of Chemically Bonded Post-installed Anchors In Low Strength Reinforced Concretes

Maziliguney, Levent 01 June 2007 (has links) (PDF)
After the 1999 Kocaeli Earthquake, the use of chemically bonded post-installed anchors has seen a great growth for retrofits in Turkey. Currently, chemically bonded post-installed anchors are designed from related tables provided by adhesive manufacturers and a set of equations based on laboratory pullout tests on normal or high strength concretes. Unfortunately, concrete compressive strengths of existing buildings, which need retrofit for earthquake resistance, ranges within 5 to 16 MPa. The determination of tensile strength of chemically bonded anchors in low-strength concretes is an obvious prerequisite for the design and reliability of retrofit projects. Since chemically bonded anchors result in the failure of concrete, adhesive-concrete interface or anchored material, the ultimate resistance of anchor can be predicted through the sum of the contributions of concrete strength, properties of anchored material (which is steel for this work), and anchorage depth. In this work, all three factors and the predictions of current tables and equations related to anchorages are examined throughout site tests.
10

Strengthening of noncomposite steel girder bridges with post-installed shear connectors : fatigue behavior of the adhesive anchor

Patel, Hemal Vinod 21 November 2013 (has links)
This thesis describes part of the work associated with Project 0-6719 sponsored by the Texas Department of Transportation (TxDOT). The primary objective of the project is to examine the feasibility of strengthening older continuous multi-span steel girder bridges through the use of post-installed shear connectors. Bridges potentially eligible for retrofit have noncomposite floor systems, where the concrete slab is not attached to the steel girders with shear connectors. Many of these bridges were designed in the 1950's and 1960's for loads smaller than the standard design loads used today. A secondary objective of the project, and the main focus of this thesis, is to examine the design of post-installed shear connectors for fatigue. Of particular interest in this study is the adhesive anchor, given its convenient installation procedure but relatively poor fatigue performance in previous tests. The objectives of this thesis were to quantify the fatigue strength of the adhesive anchor, as well as quantify the shear force and slip demands on adhesive anchors in realistic bridge conditions. In regards to the first objective, twenty-six direct shear fatigue tests were performed on adhesive anchors. Each test was conducted on a single adhesive anchor in order to capture its individual cyclic load-slip behavior. Results indicate that adhesive anchors have considerably higher fatigue strength than conventional welded shear studs, making partial composite design feasible in the strengthening of older steel bridges. In regards to the second objective, analytical and computational studies were conducted on composite beams with adhesive anchors. Results show that the shear force and slip demands are typically smaller than the endurance limits determined from direct-shear testing. This suggests that fatigue failure of adhesive anchors under service loads may not be a primary concern. Based on the results, preliminary recommendations for the design of adhesive anchors for fatigue are provided. / text

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