Digital Commons Network^™

High-Resolution Mapping In Manus Basin, C. Roman, V. Ferrini

Christopher N. Roman

Near-bottom seafloor mapping with precisely navigated deep submergence vehicles has become increasingly common in a range of oceanographic settings. Recent mapping efforts at deep-water hydrothermal vent sites have resulted in high-resolution (sub-meter) bathymetry datasets that can be used to identify morphological features associated with volcanic, tectonic, and hydrothermal processes. The resolution of these maps, and our ability to accurately quantify the complex morphologic details of hydrothermal structures has been limited by a number of variables including navigational accuracy, sonar settings (e.g. acoustic wavelength, sonar orientation, ping rate), survey parameters (e.g. altitude, speed), data density, and data processing techniques (e.g. gridding …

Tribo-Surface Characteristics Of Al-B4c And Al-Sic Composites Worn Under Different Contact Pressures

A.S. Md Abdul Haseeb

Tribo-surface characteristics of two aluminium metal matrix composites (Al-MMC) of compositions Al-13 vol%B4C and Al-13 vol%SiC sliding against a commercial phenolic brake pad have been investigated under dry conditions. The wear tests were carried out using a pin-on-disc type apparatus at a linear speed of 1.62 m s-1 under contact pressures ranging from 0.75 to 3.00 MPa. The coefficient of friction was recorded on line. Wear rates were calculated from mass loss measurements. Scanning electron microscope equipped with energy dispersive X-ray spectroscopy was used to examine the tribo-surface. It is found that wear rate of both composites increases with increasing …

Consistency Based Error Evaluation For Deep Sea Bathymetric Mapping With Robotic Vehicles, Christopher Roman, Hanumant Singh

Christopher N. Roman

This paper presents a method to evaluate the mapping error present in point cloud terrain maps created using robotic vehicles and range sensors. This work focuses on mapping environments where no a priori ground truth is available and self consistency is the only available check against false artifacts and errors. The proposed error measure is based on a disparity measurement between common sections of the environment that have been imaged multiple times. This disparity measure highlights inconsistency in the terrain map by showing regions where multiple overlapping point clouds do not fit together well. This error measure provides the map …

Velocity Imaging For The Liquid–Gas Interface In The Near Field Of An Atomizing Spray: Proof Of Concept, David L. Sedarsky, Megan E. Paciaroni, Mark A. Linne, James R. Gord, Terrence R. Meyer

Terrence R Meyer

We describe adaptation of ballistic imaging for the liquid core of an atomizing spray. To describe unambiguously the forces that act to break apart the liquid core in a spray, one must directly measure the force vectors themselves. It would be invaluable, therefore, to obtain velocity and acceleration data at the liquid-gas interface. We employ double-image ballistic imaging to extract velocity information through the application of image analysis algorithms. This method is shown to be effective for liquid phase droplet features within the resolution limit of the imaging system. In light of these results, it is clear that a three- …

Numerical Prediction And Practical Improvement Of Pulverized Coal Combustion In Blast Furna, Wei-Hsin Chen

Wei-Hsin Chen

No abstract provided.

Maintenance Outsourcing Of A Multi-Process Manufacturing System With Multiple Contractors, Hakan Tarakci, Kwei Tang, Herb Moskowitz, Robert Plante

Hakan Tarakci

Consider a manufacturer with a manufacturing system that consists of multiple processes. The manufacturer’s revenue is determined by the minimum of the uptimes among the processes. The maintenance functions of the processes are outsourced to independent contractors so that each contractor is responsible only for one process. A performance-based incentive contract is offered to each contractor, consisting of an uptime target level and a bonus rate for exceeding the uptime target. Under the incentive contract, a contractor receives a bonus only when the achieved uptime exceeds the target level specified in the contract. We develop a model for jointly determining …

Relationship Between Vertical Shear Rate And Kinetic Energy Dissipation Rate In Stably Stratified Flows, Stephen De Bruyn Kops, D. Hebert

Stephen de Bruyn Kops

High resolution direct numerical simulations of strongly stratified turbulence are analyzed in order to investigate the relationship between vertical shearing of horizontal motions and the dissipation rate of kinetic energy. The relative magnitude of each component of the dissipation rate is examined as a function of the Reynolds number and of the buoyancy Reynolds number. From the simulation results, in conjunction with published laboratory results, it is concluded that (1) the simulation results are consistent with the laboratory data but span a much larger range of buoyancy Reynolds number, (2) the ratio of the square of the vertical shear rate …

Melt Dispersion Mechanism For Fast Reaction Of Nanothermites, Valery I. Levitas, Blaine W. Asay, Steven F. Son, Michelle Pantoya

Steven F. Son

An unexpected mechanism for fast oxidation of Alnanoparticles covered by a thin oxide shell (OS) is proposed. The volume change due to melting of Al induces pressures of 0.1–4GPa and causes spallation of the OS. A subsequent unloading wave creates high tensile pressures resulting in dispersion of liquid Al clusters, oxidation of which is not limited by diffusion (in contrast to traditional mechanisms). Physical parameters controlling this process are determined. Methods to promote this melt dispersion mechanism, and consequently, improve efficiency of energetic nanothermites are discussed.

Insisting On Truth At The Expense Of Conceptualization: Can Engineering Portfolios Help?, Ozgur Eris

Ozgur Eris

Teaching and promoting conceptual thinking in engineering education is challenging. Two recently introduced design thinking models are compared in order to explore the reasons behind this challenge. The comparison results in key distinctions between divergent and convergent thinking, and between concept and knowledge domains. The differentiating principle is shown to be a common principle of the two models, truth-value, or logical status, of the propositions that engineers make. Building on this insight, divergent thinking by inquiry is identified as a mechanism for promoting conceptual thinking, and a specific implementation of engineering portfolios is proposed as a pedagogical tool.

Scavenging Waves And Influence Distances Of Gas Absorption Around Single Liquid Aerosols In Clouds, Wei-Hsin Chen

Wei-Hsin Chen

No abstract provided.

Air Pollutant Absorption By Single Moving Droplets With Drag Force At Moderate Reynolds Numbers, Wei-Hsin Chen

Wei-Hsin Chen

30 Adet Pantone Rengin Ink Formulation Programi Kullanilarak Hazirlanmasi, Bilge N. Altay, Nazli Burcu Taklak

Bilge Nazli Altay

Modeling Of The Effects Of Athermal Flow Strength And Activation Energy For Dislocation Glide On The Nanoindentation Creep Of Nickel Thin Film At Room Temperature

A.S. Md Abdul Haseeb

Nanoindentation creep behaviour of nickel at room temperature has been modeled based on the obstacle-controlled dislocation glide mechanism. Using the model, the effects of two important materials parameters viz. the activation free energy required by dislocation to overcome an obstacle without any aid from external stress, ΔF and the athermal flow strength, τ0, which is the flow strength of solids at 0 K are systematically studied. It has been found that ΔF plays a dominant role in room temperature creep properties of nickel. The role of ΔF is particularly dominant in determining the time dependent deformation. On the other hand, …

Incentive Maintenance Outsourcing Contracts For Channel Coordination And Improvement, Hakan Tarakci, Kwei Tang, Herb Moskowitz, Robert Plante

Hakan Tarakci

Consider a manufacturer who has a process with an increasing failure rate over time. In order to improve the process performance, the following two types of maintenance activity are outsourced to an external contractor: (i) preventive maintenance is performed periodically to improve the reliability of the process when the process is functional; and (ii) corrective maintenance is used to restore the process to a specified condition when it fails. We consider the use of incentive contracts to induce the contractor to select the maintenance policy that optimizes the total profit of the manufacturer and contractor. It is demonstrated that an …