Engineering Commons^™

Science For Stewardship: Multidisciplinary Research On Uss Arizona, Matthew A. Russell, Larry E. Murphy, Donald L. Johnson, Timothy J. Foecke, Pamela J. Morris, Raphy Mitchell

Department of Mechanical and Materials Engineering: Faculty Publications

The National Park Service’s Submerged Resources Center and USS Arizona Memorial are conducting and coordinating research directed at understanding the nature and rate of natural processes affecting the deterioration of the USS Arizona in Pearl Harbor, Hawaii. The USS Arizona Preservation Project is designed to be multi-year, interdisciplinary and cumulative, with each element contributing to developing an overall management strategy designed to minimize environmental hazard from fuel oil release and provide the basic research required to make informed management decisions for long-term preservation. The primary project focus is toward acquiring requisite data for understanding the complex corrosion and deterioration processes …

Chemical/Mechanical Analyses Of Anhydride-Cured Thermosetting Epoxys: Dgeba/Nma/Bdma, Wei Chian, Delmar C. Timm

Papers in Molecular Chemistry

The chemical state of cure in a thermosetting resin was used to predict the resin’s equilibrium modulus. High performance liquid chromatography analyses of the sol fraction yielded molar dynamics for monomeric, oligomeric, and polymeric molecules. Their population density distributions were compared with theoretical predictions based on a chain-growth polymerization mechanism. The resulting chemical estimates of the state of cure were integrated into calculations yielding concentrations of network structures within the gel that contribute to the density of elastically active strands and junctions. The theory of rubber elasticity was then used to predict the equilibrium modulus. Measurements incorporated dynamic mechanical analysis. …

Kinetic Reaction Analysis Of An Anhydride-Cured Thermoplastic Ep-Oxy:Pge/Nma/Bdma, Wei Chian, Delmar C. Timm

Papers in Molecular Chemistry

A comprehensive reaction analysis of a linear epoxy resin cured with an anhydride was performed to evaluate the reaction rate expressions. Monomers included phenyl glycidyl ether and methyl- 5-norbornene-2,3-dicarboxylic anhydride or nadic methyl anhydride; the catalyst was N,N-dimethylbenzylamine; the initiator was n-propanol. Emphasis was initially placed on the molar dynamics of monomeric and oligomeric molecules. Molecular fractionations were achieved using reversed phase, high performance liquid chromatography. Chemical reaction rate constants were examined as a function of degree of polym-erization. For the chain-initiated polymerization, the initiation rate constant was observed to be approximately 3 times greater than the propagation constant associated …

Optical Properties Of SioX Nanostructured Films By Pulsed-Laser Deposition At Different Substrate Temperatures, X. Y. Chen, Yongfeng Lu, Y. H. Wu, B. J. Cho, W. D. Song, D. Y. Dai

Department of Electrical and Computer Engineering: Faculty Publications

Silicon oxide sSiO_xd nanostructured films have been formed by pulsed-laser deposition of Si in oxygen at different substrate temperatures, in order to study the structures and optical properties related to quantum confinement effects. After laser ablation, the single-crystal Si(100) target is converted to a polycrystal structure and shows weak photoluminescence (PL). The as-deposited SiO_x nanostructured films show large particles (i.e., droplets) on a uniform background film. The droplets with weak PL emission have the same high crystallinity as the Si(100) target. Strong PL is observed from the amorphouslike background films rather than from the crystalline droplets. As …

Acuta Enews September 2004, Vol. 33, No. 9

ACUTA Newsletters

ln This lssue

ACUTA Joins lntemet2

From ACUTA Headquarters...................... Jeri Semer, CAE, Executive Director

Board Report................................ Carmine Piscopo, Providence College, ACUTA Secretary/Treasurer

Looking Back at the 33rd Annual Conference

So Many Winners....................... Such Nice Prizes

The University of Texas at Austin Unveils UTOPIA

Tech Talk....................... Kevin Tanzilo, Dux Public Relations

DC Update.................. Whitney Johnson, Retired, Northem Michigan Univ.

ACUTA Members Sites to See

Dynamic Testing Of Wooden Guardrail Posts - White And Red Pine Species Equivalency Study, John R. Rohde, Jason A. Hascall, Karla A. Polivka, Dean L. Sicking, Ronald K. Faller

Nebraska Department of Transportation: Research Reports

No abstract provided.

Peer Review Of Teaching Project: Survey Of Project Participants, Paul Savory, Amy M. Goodburn, Amy Nelson Burnett

Department of Industrial and Management Systems Engineering: Reports

In planning for the future of the Peer Review of Teaching project, we performed a survey of to collect faculty participant feedback on their experience in the project (i.e., writing a course portfolio, possibly having it externally reviewed) and the impact that the experience has had on their teaching. While each of the partner campuses (University of Nebraska-Lincoln, University of Michigan, Kansas State, Texas A&M, Indiana – Bloomington, and University of Kansas) have shaped the project experience differently for campus participants, we sought feedback from participants of all the project partners to get an overall assessment of the project.

Optical Modeling Of Iridium Thin Film Erosion Under Oxygen Plasma Exposure*, Li Yan, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

This work is motivated by interest in use of iridium metal films in the space environment. Optical metrology is a sensitive tool for study of film roughness, optical constants, and microstructural properties. In the present paper, in situ spectroscopic ellipsometry is applied to monitor oxygen plasma etching of films of iridium/chromium on fused silica substrates, using an electron cyclotron resonance plasma source. Optical modeling allows for a fundamental understanding of the plasma etching mechanism. Analysis of spectroscopic psi and delta data at selected time slices suggests the iridium film is etched away gradually upon plasma irradiation, while showing no signs …

Developments Of The Midwest Guardrail System For Standard And Reduced Post Spacing And In Combination With Curbs, Karla A. Polivka, Dean L. Sicking, John R. Rohde, Robert W. Bielenberg M.S.C.E., E.I.T., Ronald K. Faller, John D. Reid, James C. Holloway, Beau D. Kuipers

Nebraska Department of Transportation: Research Reports

No abstract provided.

First-Principles Study Of Adsorption Of Methanethiol On Co(0001), Ligen Wang, Evgeny Y. Tsymbal, Sitaram Jaswal

Materials Research Science and Engineering Center: Faculty Publications

Investigation of the resident site and the adsorption phase structure of thiolates is of fundamental importance for understanding the formation of self-assembled organic monolayers on metal substrate surfaces. In the present study, we have investigated adsorption of methanethiol, CH₃SH, on the ferromagnetic Co (0001) surface using density functional theory calculations.We find that the dissociative adsorption of CH₃SH forming an adsorbed methylthiolate (CH₃S) and an adsorbed H atom is energetically favorable, and that the CH₃S molecule adsorbed at the threefold fcc and hcp hollow sites is most stable. The adsorption energy at the …

Laser-Assisted Nanoscale Deposition Of Diamond-Like Carbon Films On Tungsten Tips, J. Shi, Yongfeng Lu, R. S. Cherukuri, K. K. Mendu, D. W. Doerr, Dennis R. Alexander, L. P. Li, X. Y. Chen

Department of Electrical and Computer Engineering: Faculty Publications

Diamond-like carbon (DLC) films were deposited on tungsten tips under KrF excimer laser irradiation in benzene solution. The deposition process was found to be highly dependent on tip sharpness. Tips with larger curvature radii and smaller aspect ratios could not be coated with DLC films under the same condition as that for sharp tips. Raman spectra showed that more sp³ tetrahedral structures were present in the DLC films on a tip with a smaller curvature radius. Simulation results showed that the tip sharpness dependent local optical enhancement played an important role in the DLC deposition process. An optical field …

Acuta Enews August 2004, Vol. 33, No. 8

ACUTA Newsletters

In This lssue

ACUTA Board & Committee Changes.................. Tamaro Closs, Georgetown Univ., ACUTA President-Elect

Tech Talk........................... Kevin Tanzillo, Dux Public Relations

LAN Cabling-When Too Much Bandwidth ls Never Enough . Aref Baddar, NextGen/ General Cable

DC Update..................... Whitney Johnson, Retired, Northern Michigan Univ.

Meet Amy White, ACUTAs New Accounting & Administrative Assistant

Welcome New Members

The Effect Of Heterogeneity On Plane Wave Propagation Through Layered Composites, X. Chen, Namas Chandra

Department of Mechanical and Materials Engineering: Faculty Publications

When laminated composites are subjected to impact loading, the material response is critically determined by the interactions of multiple waves generated at the laminate interfaces. Due to the high complexity arising from the architectural details of composites, layered heterogeneous materials have been studied as the model system to understand the impact behavior of engineering composites. Previously, the present authors have developed an analytical solution to the problem of plate impact of layered systems; plate impact test is a standard boundary value problem used to study high velocity impact behavior both in the elastic and shock wave regimes. In this paper, …

Odor, H2S And Nh3 Emissions From Phototrophic And Non-Phototrophic Anaerobic Swine Lagoons, Jason Byler, Dennis D. Schulte, Richard K. Koelsch

Department of Agricultural and Biological Systems Engineering: Presentations and White Papers

Odor, ammonia and hydrogen sulfide emission data were collected from three phototrophic and three non-phototrophic anaerobic swine lagoons in eastern Nebraska from May 27th to June 18th (late spring) and from July 7th to August 13th (summer). The greatest odor, hydrogen sulfide and ammonia emission rates were from non-phototrophic lagoons during late spring (24.5 OU m^-2 s^-1, 3.2 μg-H₂S m^-2 s^-1, 34.9 kg NH₃-N ha^-1 d^-1, respectively). Non-phototrophic lagoon odor, ammonia and hydrogen sulfide emission rates were much higher in late spring than summer (24.5 vs. 4.8 …

Determination Of Traffic Responsive Plan Selection Factors And Thresholds Using Artificial Neural Networks, Anuj Sharma

Department of Civil and Environmental Engineering: Faculty Publications

Traffic congestion has become a menace to civilized society. It degrades air quality, jeopardizes safety and causes delay. Traffic congestion can be alleviated by providing an effective traffic control signal system. Closed-loop traffic control systems are an example of such a system.

Closed-loop traffic control systems can be operated primarily in either of two modes: Time of Day Mode (TOD) or Traffic Responsive Plan Selection Mode (TRPS). TRPS mode, if properly configured, can easily handle time independent variation in traffic volumes. It can also reduce the effect of timing plan aging. Despite these advantages, TRPS mode is not used as …

Field-Controlled Domain-Wall Resistance In Magnetic Nanojunctions, John D. Burton, Arti Kashyap, Mikhail Ye. Zhuravlev, Ralph Skomski, Evgeny Y. Tsymbal, Sitaram Jaswal, O.N. Mryasov, R.W. Chantrell

Materials Research Science and Engineering Center: Faculty Publications

The electrical resistance of a constrained domain wall in a nanojunction is investigated using micromagnetic modeling and ballistic conductance calculations. The nanojunction represents two ferromagnetic electrodes connected by a ferromagnetic wire of 10 nm in length and of a few nanometers in cross section. We find that the anisotropy of the electrodes favors a localization of the domain wall within the constriction (wire) revealing a positive domain-wall resistance. An applied magnetic field moves the domain wall toward one of the electrodes and reduces its width. This compression of the domain wall leads to a sizeable enhancement of the domain-wall resistance.

The Effect Of Transition Metal Additions On The Microstructure And Properties Of Nanocomposite Pr–Fe–B Permanent Magnets, Jeffrey E. Shield, Yi Liu, R. Marr, Z. Chen, Baomin Ma

Materials Research Science and Engineering Center: Faculty Publications

Permanent magnets with the general composition Pr₉ (Fe_0.95Co_0.05)_85.5M_0.5B₅, where M denotes a transition metal, have been produced by melt spinning. The effect on the microstructure and magnetic properties of eight different alloying elements has been examined. The grain size and distribution have been correlated to the maximum energy product obtained. The grain size of the Pr₉ (Fe_0.95Co_0.05) _85.5B₅ control alloy was determined to be 17.5 nm, and it was found that the grain size was not significantly reduced compared to the control …

Domain-Wall Pinning At Inhomogenities Of Arbitrary Cross-Sectional Geometry, Ralph Skomski, Jian Zhou, Arti Kashyap, David J. Sellmyer

Materials Research Science and Engineering Center: Faculty Publications

Abstract—The coercivity of cellular Sm-Co based permanent magnets is investigated by model calculations. The grain boundaries responsible for the pinning coercivity are modeled as planar inhomogenities with arbitrary cross-sectional geometry. The calculation yields a physically transparent integral equation for the pinning energy, whose derivative is the pinning force. The theory rationalizes experimental data on a semiquantitative level, but without adjustable parameters, and bridges the gap between smooth concentration gradients and abrupt interfaces. Explicit results are obtained for sinoidal profiles, for very thin grain boundaries, and for profiles intermediate between attractive and repulsive pinning. The corrections predicted by the present model …

Magnetization Reversal And Giant Coercivity In Sm-Co/Cu-Ti Particulate Films, Jian Zhou, Arti Kashyap, Yi Liu, Ralph Skomski, David J. Sellmyer

Materials Research Science and Engineering Center: Faculty Publications

Highly coercive granular SmCo/CuTi films were produced by thermal processing of sputtered SmCo₅ (CuTi) multilayers and investigated experimentally and theoretically. Electron microscopy shows that the processed films consist of spherical grains that have diameters of 5–10 nm and are embedded in a matrix. Both the grains and the matrix phase exhibit the CaCu₅ structure, but the matrix is probably Cu-rich. The films have high coercivities of up to 50.4 kOe at 300 K. Analytical calculations and micromagnetic simulations yield a transition from a nucleation-type weak-interaction regime to a discrete-pinning-type strong-interaction regime. The transition occurs at packing fractions similar …

Development Of Rural Bicycle Compatibility Index, Elizabeth G. Jones

Nebraska Department of Transportation: Research Reports

No abstract provided.

Acuta Enews July 2004, Vol. 33, No. 7

ACUTA Newsletters

In This lssue

Meet the Board for 2004-05

From ACUTA Headquarters.................... Jeri A. Semer, CAE, Executive Director

Tech Talk......................... Kevin Tanzillo, Dux Public Relations

DC Update..................... Whitney Johnson, Retired, Northern Michigan Univ.

Recapturing Long-Distance Revenues..................... Mark Allen, MobilSphere

2005 ACUTA Seminar Topics Announced

Board Report................................. Carmine Piscopo, Providence College, ACUTA Secretory/Treasurer

Welcome New Members

L10 Ordered Fept:C Composite Films With (001) Texture, M. L. Yan, Renat F. Sabiryanov, Yinfan Xu, Xingzhong Li, David J. Sellmyer

Materials Research Science and Engineering Center: Faculty Publications

Highly textured (001) FePt:C nanocomposite thin films, deposited directly on thermally oxidized Si wafers, are obtained by multilayer deposition plus subsequent thermal annealing. Nanostructures, crystalline orientations, interactions, and magnetic properties are investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), magnetic force microscopy, and magnetic measurements. The formation of the ordered L1₀ phase is confirmed by XRD, and only visible (00 ) peaks indicate a high degree of the (001) texture. TEM observation reveals that FePt grains are embedded in the C matrix and appear to be well isolated.

Nanostructure And Magnetic Properties Of Fept :C Cluster Films, Yinfan Xu, M. L. Yan, David J. Sellmyer

Materials Research Science and Engineering Center: Faculty Publications

Magnetic properties and nanostructure of FePt : C cluster-deposited films with C volume fraction of 7%, 14%, 33%, and 45% have been studied. As-deposited FePt : C films were prepared by a multilayer method in which FePt layers were deposited from a cluster source employing a gas-aggregation technique and C layers from a normal sputtering gun. In the as-deposited films, FePt clusters with fcc structure are embedded in the C matrix. The high anisotropy FePt L1₀ cluster structure was realized in the films via post-deposition annealing and the nanostructure of the films was observed by high-resolution transmission electron microscope …

Magnetization Processes In Melt-Spun Sm-Co-Based Alloys With The Tbcu7-Type Structure, A. Hsiaoa, S. Aich, L. H. Lewis, Jeffrey E. Shield

Materials Research Science and Engineering Center: Faculty Publications

The initial magnetization processes in melt-spun Sm-Co alloys with remanent ratios above 0.7 have been studied. Alloys of (Sm_(1/(6+x) Co _(5+x)/(6+x) ) ₉₄Nb₃C₃ (x = 067, 1.7, 2.3 and 3) alloys modified with Nb and C were melt spun at wheel speeds of 20 and 40 m/s, and the compositions span the range between the Sm₂Co₁₇ and SmCo_{5 stoichiometries. Structurally, all alloys formed in the TbCu7-type structure, although a small amount of Sm2Co7 was observed in Sm-rich samples, and a small amount of fcc Co formed …}

Conductive Concrete For Bridge Deck Deicing And Anti-Icing, Christopher Y. Tuan

Nebraska Department of Transportation: Research Reports

No abstract provided.

A Nebraska Odor Footprint Tool For Planning Pork Facilities, Richard Koelsch

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Pork producers and rural communities are struggling to balance air quality issues (primarily odors) with the presence and growth of the industry. Currently the type of pork facility, odor control measures, prevailing wind direction, atmospheric conditions, and a community's tolerance to some degree of odor are largely ignored in the planning process because scientific tools that incorporate this information are lacking. Without such tools, decisions on setback distances and acceptable type and size of facilities are influenced by a range of arguments, often emotional in nature. In addition, pork producers lack tools to assist in evaluating impact on a rural …

Final Report: Engineering Design Of Stable Immobilized Enzymes For The Hydrolysis And Transesterification Of Triglycerides, Dr.Hossein Noureddini, Gustavo F. Larsen

Department of Chemical and Biomolecular Engineering: Funded Proposals

Enzyme Immobilization. Work will continue in the area of enzymatic transesterification reaction (biodiesel). Both methyl and ethyl esters will be used in this study. Unlike the chemical reaction where methanol has a clear advantage over ethanol, ethanol can be used as easily as methanol in the enzymatic reaction.
Sol/Gel Structure Modification. Work will concentrate on the effect of the vacuum procedure on pore size and distribution for the transesterification reaction. Additives such as glucose have been very effective in the hydrolysis reaction and will be explored further in the transesterification reaction.
Characterization. The developed material will be characterized for the …

Spinning Continuous Fibers For Nanotechnology, Yuris A. Dzenis

Department of Engineering Mechanics: Faculty Publications

Nanotubes of carbon and other materials are arguably the most fascinating materials playing an important role in nanotechnology today. Their unique mechanical, electronic, and other properties are expected to result in revolutionary new materials and devices. However, these nanomaterials, produced mostly by synthetic bottom-up methods, are discontinuous objects, and this leads to difficulties with their alignment, assembly, and processing into applications. Partly because of this, and despite considerable effort, a viable carbon nanotube–reinforced supernanocomposite is yet to be demonstrated. Advanced continuous fibers produced a revolution in the field of structural materials and composites in the last few decades as a …

Re-Examination Of “Missing Strain” During Superplastic Deformation Of Aa7475, M. J. Tan, C. L. Chen, Namas Chandra

Department of Mechanical and Materials Engineering: Faculty Publications

“Missing strain,” a discrepancy between the total macroscopic strain and the strain contributed by grain boundary sliding (GBS) during superplastic deformation, appears to exist in previous investigations. In this work, the contri¬bution of GBS (ξ_GBS) and intragranular strain (ξ_IG) were simultaneously measured using scratch test conducted on AA7475 samples after deformation at 500 °C at initial strain rate of 10^-3 s^-1. The result shows that the missing strain results most probably from the neglect of the intragranular strain as well as the anisotropic GBS-induced underesti¬mation of ξ_GBS. The calculation of ξ …

Optimization Of Cell Density And Dilution Rate In Pichia Pastoris Continuous Fermentations For Production Of Recombinant Proteins, Wenhui Zhang, Chih-Ping Liu, Mehmet Inan, Michael M. Meagher

Papers in Biomolecular Engineering

This paper provides an approach for optimizing the cell density (X_c) and dilution rate (D) in a chemostat for a Pichia pastoris continuous fermentation for the extracellular production of a recombinant protein, interferon τ (INF-τ). The objective was to maximize the volumetric productivity (Q, mg INF-τ I^-1 h^-1), which was accomplished using response surface methodology (RSM) to model the response of Q as a function of X_c and D within the ranges 150 ≤ X_c ≤ 450 g cells (wet weight) l^-1 and 0.1 μm ≤ D …