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636 full-text articles. Page 26 of 27.

Investigating Properties Of Pavement Materials Utilizing Loaded Wheel Tester (Lwt), Hao Wu 2011 University of Tennessee, Knoxville

Investigating Properties Of Pavement Materials Utilizing Loaded Wheel Tester (Lwt), Hao Wu

Doctoral Dissertations

Loaded wheel tester (LWT) is a common testing equipment usually used to test the permanent deformation and moisture susceptibility of asphalt mixtures by applying moving wheel loads on asphalt mixture specimens. It has been widely used in the United States since 1980s and practically each Department of Transportation or highway agency owns one or more LWT(s). Compared to other testing methods for pavement materials, LWT features movable wheel loads that allow more realistic situations existing on the actual pavement to be simulated in the laboratory. Due to its potential of creating a condition of repetitive loading, the concept of ...


Early-Age Shrinkage Of Ultra High-Performance Concrete: Mitigation And Compensating Mechanisms, Ahmed Mohammed Soliman 2011 The University of Western Ontario

Early-Age Shrinkage Of Ultra High-Performance Concrete: Mitigation And Compensating Mechanisms, Ahmed Mohammed Soliman

Electronic Thesis and Dissertation Repository

The very high mechanical strength and enhanced durability of ultra high-performance concrete (UHPC) make it a strong contender for several concrete applications. However, UHPC has a very low water-to-cement ratio, which increases its tendency to undergo early-age shrinkage cracking with a risk of decreasing its long-term durability. To reduce the magnitude of early-age shrinkage and cracking potential, several mitigation strategies have been proposed including the use of shrinkage reducing admixtures, internal curing methods (e.g. superabsorbent polymers), expansive cements and extended moist curing durations. To appropriately utilize these strategies, it is important to have a complete understanding of the driving ...


A Large Deformation, Rotation-Free, Isogeometric Shell, D. J. Benson, Y. Bazilevs, Ming-Chen Hsu, T. J. R. Hughes 2011 University of California, San Diego

A Large Deformation, Rotation-Free, Isogeometric Shell, D. J. Benson, Y. Bazilevs, Ming-Chen Hsu, T. J. R. Hughes

Ming-Chen Hsu

Conventional finite shell element formulations use rotational degrees of freedom to describe the motion of the fiber in the Reissner–Mindlin shear deformable shell theory, resulting in an element with five or six degrees of freedom per node. These additional degrees of freedom are frequently the source of convergence difficulties in implicit structural analyses, and, unless the rotational inertias are scaled, control the time step size in explicit analyses. Structural formulations that are based on only the translational degrees of freedom are therefore attractive. Although rotation-free formulations using C0 basis functions are possible, they are complicated in comparison to their ...


Porosity Reduction Model In Titanium– Hydroxyapatite Fgm Composites Using Shrinkage Measurement, Ahmed A. Madfa 2011 Department of Conservative Dentistry, Faculty of Dentistry, University of Thamar, Thamar, Yemen

Porosity Reduction Model In Titanium– Hydroxyapatite Fgm Composites Using Shrinkage Measurement, Ahmed A. Madfa

Ahmed A. Madfa

A multilayered titanium (Ti)–hydroxyapatite (HA) functionally graded material was produced via pressureless sintering at 1100uC. The initial and final porosities were determined via shrinkage measurements. The final porosity verification was carried out by the Archimedes method. The experimental porosity measurements were compared with two proposed models. The macroscopic and microstructure features and the measured porosities confirmed that the volume fraction porosity was associated with both matrix and reinforcing particles in all cases. The percolation threshold was observed at x50?75 in the xTiz(12x)HA mixture.


Fabrication And Characterization Of Graphene Hydrogel Via Hydrothermal Approach As A Scaffold For Preliminary Study Of Cell Growth, Huang Nay Ming 2011 University of Malaya

Fabrication And Characterization Of Graphene Hydrogel Via Hydrothermal Approach As A Scaffold For Preliminary Study Of Cell Growth, Huang Nay Ming

Huang Nay Ming

Three-dimensional assembly of graphene hydrogel is rapidly attracting the interest of researchers because of its wide range of applications in energy storage, electronics, electrochemistry, and waste water treatment. Information on the use of graphene hydrogel for biological purposes is lacking, so we conducted a preliminary study to determine the suitability of graphene hydrogel as a substrate for cell growth, which could potentially be used as building blocks for biomolecules and tissue engineering applications. A three-dimensional structure of graphene hydrogel was prepared via a simple hydrothermal method using two-dimensional large-area graphene oxide nanosheets as a precursor. The concentration and lateral size ...


Nanosized Molecular Sieves Utilized As An Environmentally Friendly Alternative To Antioxidants For Lubricant Oils, Eng-Poh Ng Dr. 2011 Universiti Sains Malaysia, Penang

Nanosized Molecular Sieves Utilized As An Environmentally Friendly Alternative To Antioxidants For Lubricant Oils, Eng-Poh Ng Dr.

Eng-Poh Ng

Lubricants play a significant part in current environmental considerations since they are an integral and indispensable component of modern technology. The production, application and disposal of the lubricants have to follow increasingly strict requirements for protecting the environment and living organisms. In this respect, molecular sieve (LTL type zeolite) is investigated as a potential environmentally friendly alternative to traditional antioxidant additives for lubricant oils. Accelerated oxidation experiments using pure base oil and additivated base oil in the presence of the LTL molecular sieve are carried out in parallel, and the oxidation processes are monitored by FT-IR spectroscopy, spectrophotometry, chromatography, total ...


Seismic Hazard Mitigation Of Building Structures Using Magneto-Rheological Dampers, Yunbyeong Chae 2011 Lehigh University

Seismic Hazard Mitigation Of Building Structures Using Magneto-Rheological Dampers, Yunbyeong Chae

Theses and Dissertations

No abstract provided.


Evaluation Of Unbonded Strand Reinforcement For Precast Concrete Floor Diaphragms, Timothy Allen Cullen 2011 Lehigh University

Evaluation Of Unbonded Strand Reinforcement For Precast Concrete Floor Diaphragms, Timothy Allen Cullen

Theses and Dissertations

No abstract provided.


Localized Damage Detection In Structures: A Statistics Based Algorithm Using A Densely Clustered Sensor Network, Elizabeth L. Labuz 2011 Lehigh University

Localized Damage Detection In Structures: A Statistics Based Algorithm Using A Densely Clustered Sensor Network, Elizabeth L. Labuz

Theses and Dissertations

No abstract provided.


Reliability Assessment, Performance Prediction And Life-Cycle Management Of Fatigue Sensitive Structures Based On Field Test Data, Kihyon Kwon 2011 Lehigh University

Reliability Assessment, Performance Prediction And Life-Cycle Management Of Fatigue Sensitive Structures Based On Field Test Data, Kihyon Kwon

Theses and Dissertations

No abstract provided.


Investigation Of Crumb Rubber Concrete For Blast Protection Of Buildings, Joseph Charles States 2011 Lehigh University

Investigation Of Crumb Rubber Concrete For Blast Protection Of Buildings, Joseph Charles States

Theses and Dissertations

No abstract provided.


Investigating Wood Welding Parameters Using A Prototype Welding Machine, Timothy R. Melin 2010 California Polytechnic State University - San Luis Obispo

Investigating Wood Welding Parameters Using A Prototype Welding Machine, Timothy R. Melin

Master's Theses and Project Reports

Understanding how different processing variables influence wood welded bonds is vital if the technique will ever be used to create engineered lumber without using adhesives. A variation of vibration welding, wood welding uses pressure and friction to bond materials together. During welding, heat causes a softening in the wood, a naturally occurring composite material. This softening leads to fiber entanglement and a bond forms upon cooling.

The goal of this research was to investigate several processing aspects of the wood welding procedure. A prototype wood welding machine, designed and fabricated from the ground up, was used to investigate the effects ...


Dependence Of Microstructure Evolution, Texture, And Mechanical Behavior Of A Mg Alloy On Thermo-Mechanical Input During Friction Stir Processing, Zhenzhen Yu 2010 University of Tennessee, Knoxville

Dependence Of Microstructure Evolution, Texture, And Mechanical Behavior Of A Mg Alloy On Thermo-Mechanical Input During Friction Stir Processing, Zhenzhen Yu

Doctoral Dissertations

In this thesis, the relationship among friction stir processing (FSP) parameters, microstructure evolution, texture development, and mechanical hehavior of AZ31B Mg alloy was investigated.

First of all, in order to reveal the correlation among the deformation conditions, dynamic recrystallization (DRX) mechanisms, and microstructure evolution in the Mg alloy, hot compression tests at a wide range of Zener-Hollomon parameter (Z) values were conducted. Through optical microscopic examination, it was found out that above a critical Z value, twinning influences the DRX process resulting in a more effective grain refinement, which is manifested in a significant change in the slope of the ...


Study Of Deformation Behavior Of Nanocrystalline Nickel Using Nanoindentation Techniques, Changli Wang 2010 University of Tennessee, Knoxville

Study Of Deformation Behavior Of Nanocrystalline Nickel Using Nanoindentation Techniques, Changli Wang

Doctoral Dissertations

Nanocrystalline materials with grain size less than 100 nm have been receiving much attention because of their unparallel properties compared with their microcrystalline counterparts. Because of its high hardness, nanocrystalline nickel has been used for MEMS. Long term thermomechnical properties and deformation mechanism at both ambient and elevated temperatures need to be evaluated which is vital for reliability of its applications as structural material.

In this thesis, nanoindentation creep of nanocrystalline nickel with an as-deposited grain size of 14 nm was characterized at elevated temperatures. The nanoindentation creep rate was observed to scale with temperature and applied load (or stress ...


Laser Textured Calcium Phosphate Bio-Ceramic Coatings On Ti-6al-4v For Improved Wettability And Bone Cell Compatibility, Sameer R. Paital 2010 The University of Tennessee

Laser Textured Calcium Phosphate Bio-Ceramic Coatings On Ti-6al-4v For Improved Wettability And Bone Cell Compatibility, Sameer R. Paital

Doctoral Dissertations

The interaction at the surfaces of load bearing implant biomaterials with tissues and physiological fluids is an area of crucial importance to all kinds of medical technologies. To achieve the best clinical outcome and restore the function of the diseased tissue, several surface engineering strategies have been discussed by scientific community throughout the world. In the current work, we are focusing on one such technique based on laser surface engineering to achieve the appropriate surface morphology and surface chemistry. Here by using a pulsed and continuous wave laser direct melting techniques we synthesize three dimensional textured surfaces of calcium phosphate ...


Design, Fabrication, Structural Testing, And Numerical Analysis Of A Small Scale Composite Wing, Jacob David Gaunt, Juan Carlos Flores, Vincent Andrew Perry 2010 Califoria Polytechnic State University, San Luis Obispo

Design, Fabrication, Structural Testing, And Numerical Analysis Of A Small Scale Composite Wing, Jacob David Gaunt, Juan Carlos Flores, Vincent Andrew Perry

Aerospace Engineering

A small scale composite wing based on a design found on an experimental aircraft was designed, constructed, and tested dynamically and statically. The wing was constructed similarly to an experimental aircraft wing. The performed static test was intended to produce pure bending. Strain gages were used to measure strains on the wing structure. The strains were converted to stresses to aid in analysis. The static test results suggested that the wing was actually under torsion. Four structural modes were found from the static test. A finite element analysis model was made to compare experimental results to numerical analytical results. The ...


Mechanical Behavior Of Alloy 230 At Temperatures Relevant To Ngnp Program, Sudin Chatterjee 2010 University of Nevada, Las Vegas

Mechanical Behavior Of Alloy 230 At Temperatures Relevant To Ngnp Program, Sudin Chatterjee

UNLV Theses, Dissertations, Professional Papers, and Capstones

Identification and selection of suitable structural materials for heat exchanger application within the purview of the next generation nuclear plant (NGNP) program constitute a major challenge. This challenge stems from the lack of many desired metallurgical and mechanical properties of conventional metallic materials and alloys for applications at temperatures approaching 950 oC. Nickel (Ni)-base Alloy 230 has been highly recommended as a suitable structural material for such application due to its excellent resistance to high-temperature plastic deformation and superior corrosion resistance in many hostile environments. Systematic studies on tensile, fracture toughness, creep, stress-rupture and creep-fatigue behavior of this alloy ...


Performance Of Nevada’S Aggregates In Alkali-Aggregate Reactivity Of Portland Cement Concrete, Mohammad Shahidul Islam 2010 University of Nevada Las Vegas

Performance Of Nevada’S Aggregates In Alkali-Aggregate Reactivity Of Portland Cement Concrete, Mohammad Shahidul Islam

UNLV Theses, Dissertations, Professional Papers, and Capstones

Alkali-aggregate reaction (AAR) is a form of distress that occurs in concrete and results in serviceability problems, cracks, spalling, and other deterioration mechanisms. There are two categories of AAR, namely, alkali-silica reaction (ASR) and alkali-carbonate reaction (ACR). Alkali-silica reaction is one of the most recognized deleterious phenomena in concrete, and has been a major concern since its discovery in the 1940s. The reaction which occurs between reactive silica or silicates present in some aggregates and alkalis of Portland cement produces an alkali-silica gel that expands in the presence of moisture resulting in concrete cracks. ACR is also a chemical reaction ...


Time-Temperature Curing Relationship Of An Adhesive Binder With Rice Straw, Kevin Ka-Wan Ng 2010 California Polytechnic State University - San Luis Obispo

Time-Temperature Curing Relationship Of An Adhesive Binder With Rice Straw, Kevin Ka-Wan Ng

Master's Theses and Project Reports

Rice straw is a global and proliferate agricultural waste whose production grossly outstrips viable uses. Current disposal methods are not sustainable, and more convenient methods – such as incineration – exude poor environmental stewardship. Although the direct use of straw bales in building construction presents a practical and sustainable alternative, engineering challenges associated with using it prevent its wide adoption. The Stak Block – a composite formed from compressed rice straw and a heat-cured adhesive – may overcome challenges associated with straw bale building. However, the times and temperatures needed to cure the binder with straw are not well understood. Therefore, the goal of ...


Porosity Reduction Model In Functionally Graded Metal-Ceramic Composites Using Shrinkage Measurement, Ahmed Madfa 2010 Department of Conservative Dentistry, Faculty of Dentistry, University of Thamar, Thamar, Yemen

Porosity Reduction Model In Functionally Graded Metal-Ceramic Composites Using Shrinkage Measurement, Ahmed Madfa

Ahmed A. Madfa

Porosity of metal-ceramic functionally graded materials (FGMs) was investigated experimentally to verify its mathematical models.


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