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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.
21

Properties of Activated Crumb Rubber

January 2014 (has links)
abstract: ABSTRACT Pre-treated crumb rubber technologies are emerging as a new method to produce asphalt rubber mixtures in the field. A new crumb rubber modifier industrially known as "RuBind" is one such technology. RuBindTM is a "Reacted and Activated Rubber" (RAR) that acts like an elastomeric asphalt extender to improve the engineering properties of the binder and mixtures. It is intended to be used in a dry mixing process with the purpose of simplifying mixing at the asphalt plant. The objectives of this research study were to evaluate the rheological and aging properties of binders modified with RuBindTM and its compatibility with warm mix technology. Two binders were used for this study: Performance Grade (PG) 70-10 and PG 64-22, both modified with 25% by weight of asphalt binder. Laboratory test included: penetration, softening point, viscosity, Dynamic Shear Rheometer (DSR) and Bending Beam Rheometer (BBR). Tests were conducted under original, short and long -term aging conditions. Observations from the test results indicated that there is a better improvement when RuBindTM is added to a softer binder, in this case a PG 64-22. For short-term aging, the modified binder showed a similar aging index compared to the control. However, long term aging was favorable for the modified binders. The DSR results showed that the PG 64-22 binder high temperature would increase to 82 °C, and PG 70-10 would be increased to 76 °C, both favorable results. The intermediate temperatures also showed an improvement in fatigue resistance (as measured by the Superpave PG grading parameter |G*|sinä). Test results at low temperatures did not show a substantial improvement, but the results were favorable showing reduced stiffness with the addition of RuBindTM. The evaluation of warm mix additive using EvothermTM confirmed the manufacturer information that the product should have no negative effects on the binder properties; that is the modified binder can be used in a warm mix process. These results were encouraging and the recommendation was to continue with a follow up study with mixture tests using the RuBindTM modified binders. / Dissertation/Thesis / M.S. Civil and Environmental Engineering 2014
22

The Acute Toxicity Of Ground Recycled Automobile Tires On Aquatic Life With Model Species P. Promelas

Baldassari, Trillian 01 January 2008 (has links)
Used tires have the potential for becoming popular in pollution control media used in stormwater applications including pervious pavement sub bases, green roof growth media, and upflow filters. Using tire crumb to decrease nutrients can minimize impacts on ecology while reducing the human footprint left by used tires. However, if tire crumb is not examined for toxicity, the ecological balance could unknowingly be disrupted. This research tested the acute toxicity of tire crumb in aquatic systems by finding the Lethal Concentration for 50% kill (LC50). Using an extreme tire crumb load, P. promelas (fathead minnow) were exposed to leachates created with tire crumb and several different types of water including distilled water, tap water, and detention pond water. For distilled and tap water, the addition of tire crumb increased the survival of P. promelas. For detention pond water, the addition of tire crumb decreased the survival of P. promelas, though only enough to find an LC50 for detention pond water influenced immediately by stormwater runoff. An LC50 was found when 100 percent tire crumb filtrate is prepared with 25 grams of tire crumb per liter of detention pond water collected directly after a storm. The LC50 found is resultant of a tire crumb load significantly higher than what can be expected in the environment. Based on this research, tire crumb is considered non-threatening to aquatic fish and safe to use with detention pond water.
23

A Pedagogical Guide to Extended Piano Techniques

Proulx, Jean-François January 2009 (has links)
Extended piano techniques, which mainly involve playing directly on the internal components of the piano, emerged early in the twentieth century, mainly in the United States. Henry Cowell (1897-1965) explored some of these techniques in short piano pieces such as The Tides of Manaunaun (1917; clusters) The Banshee (1925; glissando, pizzicato) and Sinister Resonance (1930; mute, harmonic). Several contemporary composers followed this path. Notably, George Crumb's (b. 1929) mature works combine conventional techniques with an unprecedented variety of extended techniques, including vocal and percussive effects. Although extended techniques are no longer a novelty, most pianists are still unfamiliar with them. Extended piano works are rarely performed or taught. This situation is regrettable considering the quality of these compositions, and the great potential of extended techniques to expand the piano's coloristic resources. A Pedagogical Guide to Extended Piano Techniques is designed to help pianists learn this idiom and achieve fluency. Teachers may also find it useful in planning courses at the undergraduate college level. Chapters 1 and 2 provide general information such as the development and classification of unconventional techniques, and the construction of the grand piano. Chapters 3, 4 and 5 form the core of the monograph. They contain practical exercises, composed by the author, presented in a progressive order and accompanied by detailed instructions explaining how to execute and practice each technique. From a technical point of view, natural string piano techniques--pizzicatos, glissandos, mutes and harmonics--are the basis upon which most other extended techniques are founded. Therefore, this document focuses mainly on mastering these string techniques through the acquisition of two important skills: visual techniques and aural-motor coordination. The following topics are also discussed: use of foreign objects inside the piano, percussive technique, vocal effects, and strategies to integrate various techniques into a unified musical context. Prepared piano techniques are excluded because they do not require the acquisition of performance skills, which form the essence of this monograph. Chapter 6 provides a suggested course schedule to organize the pianist's study and practice time, and offers practical advice for the preparation of performances involving extended piano techniques. It is hoped that this document will play a positive role in helping pianists gain the knowledge, ability, confidence and enthusiasm to explore and perform extended piano repertoire. / Music Performance
24

Analysis of harp performance issues in Federico's Little Songs for Children by George Crumb.

Hembreiker, Linda-Rose 05 1900 (has links)
During the 20th century, chamber works for harp expanded to include significantly different instrumentations, like flute, voice and harp. Indeed, a body of works for flute, voice, and harp began to develop mainly through the commissioning efforts of ensembles comprised of these instruments. This study of George Crumb's Federico's Little Songs for Children for flutes, soprano, and harp considers the unique advantages and challenges of this instrumentation and offers specific suggestions for performance. Attention to various compositional elements of Federico's Little Songs for Children, especially as they relate to the text, is also helpful in preparing to perform this work. The form, pitch material, and text-painting in the work allow for special opportunities to convey meaning to audiences in ways that do not rely on traditional tonal relationships. Accompanying the shift away from traditional tonal relationships, the development of the harp repertoire in chamber and solo settings during the 20th century also led to the development of many extended- techniques for this instrument. For the most part, these techniques have been described and given various notational symbols but not discussed in detail with regard to execution. Federico's Little Songs for Children itself requires several unique extended-techniques. Recommendations are given in this paper concerning how to achieve the extended-techniques in Crumb's work in a stylistically appropriate and effective manner.
25

Effect of using Organosilane with Crumb Rubber Modified Hot Mix Asphalt Mixtures

January 2018 (has links)
abstract: Crumb rubber use in asphalt mixtures by means of wet process technology has been in place for several years in the United States with good performance record; however, it has some shortcomings such as maintaining high mixing and compaction temperatures in the field production. Organosilane (OS), a nanotechnology chemical substantially improves the bonding between aggregate and asphalt by modifying the aggregate structure from hydrophilic to hydrophobic contributing to increased moisture resistance of conventional asphalt mixtures. Use of Organosilane also reduces the mixing and compaction temperatures and facilitates similar compaction effort at lower temperatures. The objective of this research study was first to perform a Superpave mix design for Crumb Rubber Modified Binder (CRMB) gap-graded mixture with and without Organosilane; and secondly, analyse the performance of CRMB mixtures with and without Organosilane by conducting various laboratory tests. Performance Grade (PG) 64-22 binder was used to create the gap-graded Hot Mix Asphalt (HMA) mixtures for this study. Laboratory tests included rotational viscometer binder test and mixtures tests: dynamic modulus, flow number, tensile strength ratio, and C* fracture test. Results from the tests indicated that the addition of Organosilane facilitated easier compaction efforts despite reduced mixing and compaction temperatures. Organosilane also modestly increased the moisture susceptibility and resistance to crack propagation yet retaining equal rutting resistance of the CRMB mixtures. / Dissertation/Thesis / Masters Thesis Civil, Environmental and Sustainable Engineering 2018
26

Slice Sampling with Multivariate Steps

Thompson, Madeleine 11 January 2012 (has links)
Markov chain Monte Carlo (MCMC) allows statisticians to sample from a wide variety of multidimensional probability distributions. Unfortunately, MCMC is often difficult to use when components of the target distribution are highly correlated or have disparate variances. This thesis presents three results that attempt to address this problem. First, it demonstrates a means for graphical comparison of MCMC methods, which allows researchers to compare the behavior of a variety of samplers on a variety of distributions. Second, it presents a collection of new slice-sampling MCMC methods. These methods either adapt globally or use the adaptive crumb framework for sampling with multivariate steps. They perform well with minimal tuning on distributions when popular methods do not. Methods in the first group learn an approximation to the covariance of the target distribution and use its eigendecomposition to take non-axis-aligned steps. Methods in the second group use the gradients at rejected proposed moves to approximate the local shape of the target distribution so that subsequent proposals move more efficiently through the state space. Finally, this thesis explores the scaling of slice sampling with multivariate steps with respect to dimension, resulting in a formula for optimally choosing scale tuning parameters. It shows that the scaling of untransformed methods can sometimes be improved by alternating steps from those methods with radial steps based on those of the polar slice sampler.
27

Slice Sampling with Multivariate Steps

Thompson, Madeleine 11 January 2012 (has links)
Markov chain Monte Carlo (MCMC) allows statisticians to sample from a wide variety of multidimensional probability distributions. Unfortunately, MCMC is often difficult to use when components of the target distribution are highly correlated or have disparate variances. This thesis presents three results that attempt to address this problem. First, it demonstrates a means for graphical comparison of MCMC methods, which allows researchers to compare the behavior of a variety of samplers on a variety of distributions. Second, it presents a collection of new slice-sampling MCMC methods. These methods either adapt globally or use the adaptive crumb framework for sampling with multivariate steps. They perform well with minimal tuning on distributions when popular methods do not. Methods in the first group learn an approximation to the covariance of the target distribution and use its eigendecomposition to take non-axis-aligned steps. Methods in the second group use the gradients at rejected proposed moves to approximate the local shape of the target distribution so that subsequent proposals move more efficiently through the state space. Finally, this thesis explores the scaling of slice sampling with multivariate steps with respect to dimension, resulting in a formula for optimally choosing scale tuning parameters. It shows that the scaling of untransformed methods can sometimes be improved by alternating steps from those methods with radial steps based on those of the polar slice sampler.
28

An analysis of musical time in selected works by George Crumb /

MacKay, John William. January 1979 (has links)
No description available.
29

Finite Element Analysis on the Effects of Elastomeric Inclusions for Abating Heat Transfer in Steel Reinforced Concrete Columns

January 2011 (has links)
abstract: Concrete columns constitute the fundamental supports of buildings, bridges, and various other infrastructures, and their failure could lead to the collapse of the entire structure. As such, great effort goes into improving the fire resistance of such columns. In a time sensitive fire situation, a delay in the failure of critical load bearing structures can lead to an increase in time allowed for the evacuation of occupants, recovery of property, and access to the fire. Much work has been done in improving the structural performance of concrete including reducing column sizes and providing a safer structure. As a result, high-strength (HS) concrete has been developed to fulfill the needs of such improvements. HS concrete varies from normal-strength (NS) concrete in that it has a higher stiffness, lower permeability and larger durability. This, unfortunately, has resulted in poor performance under fire. The lower permeability allows for water vapor to build up causing HS concrete to suffer from explosive spalling under rapid heating. In addition, the coefficient of thermal expansion (CTE) of HS concrete is lower than that of NS concrete. In this study, the effects of introducing a region of crumb rubber concrete into a steel-reinforced concrete column were analyzed. The inclusion of crumb rubber concrete into a column will greatly increase the thermal resistivity of the overall column, leading to a reduction in core temperature as well as the rate at which the column is heated. Different cases were analyzed while varying the positioning of the crumb-rubber region to characterize the effect of position on the improvement of fire resistance. Computer simulated finite element analysis was used to calculate the temperature and strain distribution with time across the column's cross-sectional area with specific interest in the steel - concrete region. Of the several cases which were investigated, it was found that the improvement of time before failure ranged between 32 to 45 minutes. / Dissertation/Thesis / M.S. Mechanical Engineering 2011
30

Superpave Mix Design and Laboratory Testing of Reacted and Activated Rubber Modified Asphalt Mixtures

January 2018 (has links)
abstract: Crumb rubber use in asphalt mixtures using wet process technology has been in practice for years in the United States with good performance history; however, it has some drawbacks that include the need for special blending equipment, high rubber-binder temperatures, and longer waiting time at mixing plants. Pre-treated crumb rubber technologies are emerging as a new method to produce asphalt rubber mixtures in the field. A new crumb rubber modifier known as Reacted and Activated Rubber (RAR) is one such technology. RAR (industrially known as “RARX”) acts like an Enhanced Elastomeric Asphalt Extender to improve the engineering properties of the binder and mixtures. It is intended to be used in a dry mixing process with the purpose of simplifying mixing at the asphalt plant. The objective of this research study was first to perform a Superpave mix design for determination of optimum asphalt content with 35% RAR by weight of binder; and secondly, analyse the performance of RAR modified mixtures prepared using the dry process against Crumb Rubber Modified (CRM) mixtures prepared using the wet process by conducting various laboratory tests. Performance Grade (PG) 64-22 binder was used to fabricate RAR and CRM mixtures and Performance Grade (PG) 70-10 was used to fabricate Control mixtures for this study. Laboratory tests included: Dynamic Modulus Test, Flow Number Test, Tensile Strength Ratio, Axial Cyclic Fatigue Test and C* Fracture Test. Observations from test results indicated that RAR mixes prepared through the dry process had excellent fatigue life, moisture resistance and cracking resistance compared to the other mixtures. / Dissertation/Thesis / Masters Thesis Civil, Environmental and Sustainable Engineering 2018

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