Engineering Commons^™

Effects Of Aggregate Angularity On Mix Design Characteristics And Pavement Performance, Leonardo T. Souza, Yong-Rak Kim

Nebraska Department of Transportation: Research Reports

No abstract provided.

Effects Of Aggregate Angularity On Mix Design Characteristics And Pavement Performance, Yong-Rak Kim, Leonardo T. Souza

Nebraska Department of Transportation: Research Reports

This research targeted two primary purposes: to estimate current aggregate angularity test methods and to evaluate current aggregate angularity requirements in the Nebraska asphalt mixture/pavement specification. To meet the first research objective, various aggregate angularity tests were estimated with the same sets of aggregates and were compared by investigating their characteristics on testing repeatability, cost, testing time, workability, and sensitivity of test results. For the second objective, the effect of aggregate angularity on mixture performance was investigated by conducting laboratory performance tests (the uniaxial static creep test and the indirect tensile fracture energy test) of five mixes designed with different …

Numerical Simulation Of Gas-Phonon Coupling In Thermal Transpiration Flows, Xiaohui Guo, Dhruv Singh, Jayathi Murthy, Alina A. Alexeenko

PRISM: NNSA Center for Prediction of Reliability, Integrity and Survivability of Microsystems

Thermal transpiration is a rarefied gas flow driven by a wall temperature gradient and is a promising mechanism for gas pumping without moving parts, known as the Knudsen pump. Obtaining temperature measurements along capillary walls in a Knudsen pump is difficult due to extremely small length scales. Meanwhile, simplified analytical models are not applicable under the practical operating conditions of a thermal transpiration device, where the gas flow is in the transitional rarefied regime. Here, we present a coupled gas-phonon heat transfer and flow model to study a closed thermal transpiration system. Discretized Boltzmann equations are solved for molecular transport …

Performance-Based Testing Methodology For Concrete Durability, Niall Holmes, P. A.Muhammed Basheer, Sreejith Nanukuttan, Lulu Basheer

Reports

This report presents an overview of performance based testing methodology for concrete durability and work currently underway jointly at Queens University Belfast and Heriot Watt University, Edinburgh, to undertake this research under a EPSRC funded project (EP/G02152X/1).

EN206-1 superseded BS 5328 on 1^st December 2003 and allows designers and producers to use a wide range of cements and aggregate types for a variety of exposure conditions. In this new standard, the durability of concrete is specified in terms of the constituent materials of concrete, properties of fresh and hardened concrete, limitations for concrete composition, specification of concrete, delivery of …

Conductivity Sensors To Monitor Cover-Zone Performance, W. J. Mccarter, T. M. Chrisp, G. Starrs, E. Owens, Niall Holmes, L. Basheer, S. V. Nanukuttan, M. Basheer

Conference papers

This paper presents developments in the use of an embedded, multi-electrode conductivity sensor to study the response of the concrete cover-zone to environmental action. The sensor enables an evaluation of the temporal and spatial variation of electrical conductivity thereby allowing an integrated assessment of the cover-zone. Conductivity sensors were embedded within concrete samples to study the cover-zone response to cyclic wetting and drying under laboratory conditions. This work was extended to include the use of remote interrogation methods to study samples placed at a marine exposure site and preliminary results are presented.

Presence-Dependent Performance Differences Between Virtual Simulations And Miniature Worlds, Andre Huthmann

Electronic Theses and Dissertations

The purpose of simulation is to avoid reality-based constraints by the implemen-tation of a synthetic model. Based on this advantage, interactive simulations have conquered all areas of applications from acquisition, and training, to research. Simulation results are transferred in many ways into reality and conclusions are drawn from the simulation to the application. Many anecdotal observations on human-in-the-loop simulations have shown a significant difference in actor behavior between simulations and reality-based applications. It seems that the factors that makes simulation so attractive, namely the absence of constraints and especially of imminent danger for persons and equipment, influence the behavior and …

Effects Of Aggregate Angularity On Mix Design Characteristics And Pavement Performance, Yong-Rak Kim, Leonardo T. Souza

Mid-America Transportation Center: Final Reports and Technical Briefs

This research targeted two primary purposes: to estimate current aggregate angularity test methods and to evaluate current aggregate angularity requirements in the Nebraska asphalt mixture/pavement specification. To meet the first research objective, various aggregate angularity tests were estimated with the same sets of aggregates and were compared by investigating their characteristics on testing repeatability, cost, testing time, workability, and sensitivity of test results. For the second objective, the effect of aggregate angularity on mixture performance was investigated by conducting laboratory performance tests (the uniaxial static creep test and the indirect tensile fracture energy test) of five mixes designed with different …

Ride Performance Analysis Of Half-Car Model For Semi-Active System Using Rms As Performance Criteria, Sany Ihsan, Mehdi Ahmadian, Waleed Faris, Emmanuel D. Blanchard

Faculty of Engineering - Papers (Archive)

The work aims to study the root mean square (RMS) responses to acceleration input for four state variables: the m_S vertical acceleration, the m_S pitch angular acceleration and the front and rear deflections of the suspensions. A half-car two degree-of-freedom model of semi-active control scheme is analyzed and compared with the conventional passive suspension system. Frequency response of the transfer function for the heave, pitch of the sprung mass and suspension deflections are initially compared and then mean square analysis is utilized to see the effect of semi-active scheme. Results indicate that significant improvements were achieved in the …

Adoption Of Dynamic Simulation For Energy Performance Rating Tool For Korean Residential Buildings: Edem-Samsung, Saeeta Ghauri, Cameron Johnstone, Jaemin Kim, Georgios Kokogiannakis, Paul Tuohy, Kyung-Hun Woo

Faculty of Engineering and Information Sciences - Papers: Part A

Currently, there is a high emphasis on reducing the energy consumption and carbon emissions of buildings worldwide. Korea is facing an emerging issue of energy savings in buildings in perspective of new green economic policy. In this context, various policy measures including the energy efficiency ratings for buildings are being implemented for domestic and non-domestic buildings. In practice, design teams tend to prefer easy to use assessment tools to optimise energy performance and carbon ratings while they are concerned about calculation accuracy and the accurate representation of the dynamics involved associated with the characteristics of Korean residential buildings. This paper …

The Performance Of Rail Track Incorporating The Effects Of Ballast Breakage, Confining Pressure And Geosynthetic Reinforcement, Buddhima Indraratna, S Nimbalkar, D Christie

Faculty of Engineering - Papers (Archive)

Rail tracks are often placed on ballast which offers the desirable resiliency to cyclic loads. However ballasted beds need periodic maintenance due to deformation and degradation associated with breakage and fouling. A proper understanding of load transfer mechanisms and their effect on ballast breakage are prerequisites for minimizing maintenance costs. Recycled ballast is a cheaper and environmentally viable option but its strength characteristics need to be investigated beforehand. This paper demonstrates the analytical, numerical and laboratory investigations carried out to investigate the geotechnical behavior of ballast, including shear strength, ballast breakage, and confining pressure. The potential use of geosynthetics for …

Long-Term Performance Of A Permeable Reactive Barrier In Acid Sulphate Soil Terrain, Gyanendra Regmi, Buddhima Indraratna, Long Nghiem

Faculty of Engineering - Papers (Archive)

Deep drainage technique utilised for flood mitigation in low-land coastal areas of Australia during the late 1960s has resulted in the generation of sulphuric acid in soil by the oxidation of pyritic materials. Further degradation of the subsurface environment with widespread contamination of the underlying soil and groundwater presents a major and challenging environmental issue in acid sulphate soil (ASS) terrains. Although several ASS remediation techniques recently implemented in the floodplain of Southeast Australia including operation of gates, tidal buffering and lime injections could significantly control the pyrite oxidation, they could not improve the long-term water quality. More recently, permeable …

Development And Performance Analysis Of A Saturated Core High Temperature Superconducting Fault Current Limiter, Jeffrey W. Moscrop, Scott Hopkins

Faculty of Engineering - Papers (Archive)

Recent international activity in the field of high voltage Fault Current Limiters (FCLs) has intensified since the North American blackout of 2003. A number of national and international peak body groups in the USA, Europe and Japan have been established to assess the need for FCLs and the issues associated with their design, specification, operation, protection and integration into the electricity grids. This paper details the development of a prototype 3-phase saturated core High Temperature Superconducting (HTS) FCL in Australia. Through experimental analysis, the performance of this device is characterised in terms of DC saturation, steady state performance, and fault …

Using Student Mood And Task Performance To Train Classifier Algorithms To Select Effective Coaching Strategies Within Intelligent Tutoring Systems (Its), Robert Sottilare

Electronic Theses and Dissertations

The ultimate goal of this research was to improve student performance by adjusting an Intelligent Tutoring System's (ITS) coaching strategy based on the student's mood. As a step toward this goal, this study evaluated the relationships between each student's mood variables (pleasure, arousal, dominance and mood intensity), the coaching strategy selected by the ITS and the student's performance. Outcomes included methods to increase the perception of the intelligent tutor to allow it to adapt coaching strategies (methods of instruction) to the student's affective needs to mitigate barriers to performance (e.g. negative affect) during the one-to-one tutoring process. The study evaluated …

Response Sensitivity Of Highway Bridges To Random Multi-Component Earthquake Excitation, Kyle Cronin

Electronic Theses and Dissertations

Highway bridges provide a critical lifeline during extreme seismic events and must maintain serviceability under a large range of earthquake intensities. Consequently, the advent of more computational power has allowed more advanced analysis approaches for predicting performance and vulnerability of highway bridges under these seismic loads. In traditional two-dimensional finite element analyses, it has been demonstrated that the incidence angle of the ground motion can play a significant role in structural response. As three-dimensional nonlinear time history analyses are used more frequently in practice, ground motions are still usually applied along a single bridge axis. It is unknown how three …

Optimization Of Channel Geometry In A Proton Exchange Membrane (Pem) Fuel Cell, Jephanya Kasukurthi

UNLV Theses, Dissertations, Professional Papers, and Capstones

Bipolar plates are the important components of the PEM fuel cell. The flow distribution inside the bipolar plate should be uniform. Non-uniform flow distribution inside the bipolar leads to poor performance of the fuel cell and wastage of expensive catalyst. A single channel PEM fuel cell is taken and electrochemical analysis is carried out on it. The results are compared with the available published experimental data obtained by other research group, and they are found to be in good agreement. A baseline design of the bipolar plate is taken and numerical analysis is carried out. The results show that the …

Online Performance Evaluation Of Alternative Control Strategies For Building Cooling Water Systems Prior To In-Situ Implementation, Zhenjun Ma, Shengwei Wang, Fu Xiao

Faculty of Engineering - Papers (Archive)

This paper presents the online test and evaluation of the performance of five practical control strategies (fixed set-point control method, fixed approach control method, two near optimal strategies and one optimal strategy) for building cooling water systems to identify the best strategy for future field validation. All of these strategies were tested and evaluated in a simulated virtual environment similar to the situation when they are actually implemented in practice. A virtual building system representing the real building and its central chilling system was developed and used to test the operational performance of the system controlled by different strategies. The …

The Influence Of University Entry Scores On Performance In Engineering Mechanics, Giles Thomas, Alan Henderson, Thomas L. Goldfinch

Faculty of Engineering - Papers (Archive)

An ongoing study into the causes of poor student performance in engineering mechanics has uncovered some intriguing data on the relationships between students’ university entry scores and their performance in engineering mechanics courses. Statistical analysis has shown that the expected correlations between this key measure used to determine students eligibility for study and engineering mechanics score either do not exist, or are too weak to base educational interventions on. However, students’ entry scores have instead been shown to provide a ‘risk factor’, whereby students’ risk of failing the subject can be determined by entry score ranges. These risk factors may …

Optimization Of Solid Oxide Fuel Cell Interconnect Design, Krishna C. Pulagam

UNLV Theses, Dissertations, Professional Papers, and Capstones

Performance of solid oxide fuel cells (SOFC) is dependent of a set of complex physical and chemical processes occurring simultaneously. Interconnect for SOFC is important as it provides electrical connection between anode of one individual cell to the cathode of neighboring one. It also acts as a physical barrier to protect the air electrode material from the reducing environment of the fuel on the fuel electrode side, and it equally prevents the fuel electrode material from contacting with oxidizing atmosphere of the oxidant electrode side. A three-dimensional numerical model has been developed to evaluate the SOFC including the current collector, …