Engineering Commons^™

Assessing Conceptual Models For Subsurface Reactive Transport Of Inorganic Contaminants, J.A. Davis, S.B. Yabusaki, C.I. Steefel, John M. Zachara, G.P. Curtis, G.D. Redden, L.J. Criscenti, B.D. Honeyman

United States Department of Energy: Publications

In many subsurface situations where human health and environmental quality are at risk (e.g., contaminant hydrogeology, petroleum extraction, carbon sequestration, etc.), scientists and engineers are being asked by federal agency decision-makers to predict the fate of chemical species under conditions where both reactions and transport are processes of first-order importance.

In 2002, a working group (WG) was formed by representatives of the U.S. Geological Survey, Environmental Protection Agency,Department of Energy,Nuclear Regulatory Commission, Department of Agriculture,and Army Engineer Research and Development Center to assess the role of reactive transport modeling (RTM) in addressing these situations. Specifically, the goals of the WG …

Cryogenic Laser Induced Fluorescence Characterization Of U(Vi) In Hanford Vadose Zone Pore Waters, Zheming Wang, John M. Zachara, Wassana Yantasee, Paul Gassman, Chongxuan Liu, Alan Joly

United States Department of Energy: Publications

Ambient and liquid helium temperature laser-induced time-resolved uranyl fluorescence spectroscopy was applied to study the speciation of aqueous uranyl solutions containing carbonate and phosphate and two porewater samples obtained by ultracentrifugation of U(VI)-contaminated sediments. The significantly enhanced fluorescence signal intensity and spectral resolution found at liquid helium temperature allowed, for the first time, direct fluorescence spectroscopic observation of the higher aqueous uranyl complexes with carbonate: UO₂(CO₃)₂ ^2-, UO₂(CO₃)₃ ^4-, and (UO₂)₂(OH)₃CO₃ ^-. The porewater samples were non-fluorescent at room temperature. …

Microscale Distribution Of Cesium Sorbed To Biotite And Muscovite, James Mckinley, John M. Zachara, Steven Heald, Alice Dohnalkova, Matthew Newville, Steve Sutton

United States Department of Energy: Publications

Individual 1-3 mm biotite and muscovite clasts from Hanford sediment were contacted with 0.08 M CsNO₃. They were examined using electron or X-ray microprobe methods, as intact specimens or sectioned perpendicular to their basal planes. Cs+ was observed to preferentially sorb to mica edges, steps on mica surfaces, or fractured regions. The localization of Cs conformed to hypothesized strong binding to frayed edge sites in preference to sites on basal planes. In section, Cs⁺ was found to penetrate the mica interior, forming discrete zones of concentration, particularly in muscovite. In biotite, Cs was more abundant, permeating the …

Spectroscopic And Diffraction Study Of Uranium Speciation In Contaminated Vadose Zone Sediments From The Hanford Site, Washington State, Jeffrey Catalano, Steven Heald, John M. Zachara, Gordon Brown Jr.

United States Department of Energy: Publications

Contamination of vadose zone sediments under tank BX-102 at the Hanford site, Washington, resulted from the accidental release of 7-8 metric tons of uranium dissolved in caustic aqueous sludge in 1951. We have applied synchrotron-based X-ray spectroscopic and diffraction techniques to characterize the speciation of uranium in samples of these contaminated sediments. U L_III-edge X-ray absorption fine structure (XAFS) spectroscopic studies demonstrate that uranium occurs predominantly as a uranium- (VI) silicate from the uranophane group of minerals. XAFS cannot distinguish between the members of this mineral group due to the near identical local coordination environments of uranium in …

Biogeochemical Transformation Of Fe Minerals In A Petroleum-Contaminated Aquifer, John M. Zachara, Ravi K. Kukkadapu, Paul Gassman, Alice Dohnalkova, James K. Fredrickson, Todd Anderson

United States Department of Energy: Publications

The Bemidji aquifer in Minnesota, USA is a well-studied site of subsurface petroleum contamination. The site contains an anoxic groundwater plume where soluble petroleum constituents serve as an energy source for a region of methanogenesis near the source and bacterial Fe(III) reduction further down gradient. Methanogenesis apparently begins when bioavailable Fe(III) is exhausted within the sediment. Past studies indicate that Geobacter species and Geothrix fermentens–like organisms are the primary dissimilatory Fe-reducing bacteria at this site. The Fe mineralogy of the pristine aquifer sediments and samples from the methanogenic (source) and Fe(III) reducing zones were characterized in this study to …

Chromium Speciation And Mobility In A High Level Nuclear Waste Vadose Zone Plume, John M. Zachara, Calvin Ainsworth, Gordon Brown Jr., Jeffery Catalano, James Mckinley, Odeta Qafoku, Steven Smith, James Szecsody, Sam Traina, Jeffrey Warner

United States Department of Energy: Publications

Radioactive core samples containing elevated concentrations of Cr from a high level nuclear waste plume in the Hanford vadose zone were studied to assess the future mobility of Cr. Cr(VI) is an important subsurface contaminant at the Hanford Site. The plume originated in 1969 by leakage of self-boiling supernate from a tank containing REDOX process waste. The supernate contained high concentrations of alkali (NaOH ≈ 5.25 mol/L), salt (NaNO₃/NaNO₂ >10 mol/L), aluminate [Al(OH)₄ ⁻ = 3.36 mol/L], Cr(VI) (0.413 mol/L), and ¹³⁷Cs⁺(6.51 X 10^-5 mol/L). Water and acid extraction of the oxidized …

Dissolution Of Uranyl Microprecipitates In Subsurface Sediments At Hanford Site, Usa, Chongxuan Liu, John M. Zachara, Odeta Qafoku, James Mckinley, Steve M. Heald, Zheming Wang

United States Department of Energy: Publications

The dissolution of uranium was investigated from contaminated sediments obtained at the US. Department of Energy (U.S. DOE) Hanford site. The uranium existed in the sediments as uranyl silicate microprecipitates in fractures, cleavages, and cavities within sediment grains. Uranium dissolution was studied in Na, Na-Ca, and NH₄ electrolytes with pH ranging from 7.0 to 9.5 under ambient CO₂ pressure. The rate and extent of uranium dissolution was influenced by uranyl mineral solubility, carbonate concentration, and mass transfer rate from intraparticle regions. Dissolved uranium concentration reached constant values within a month in electrolytes below pH 8.2, whereas concentrations continued …

Scintillator Detectors For Scanning Transmission X-Ray Microscopes At The Advanced Light Source, S. Fakra, A. L. D. Kilcoyne, Tolek Tyliszczak

United States Department of Energy: Publications

The choice of x-ray detectors presents a challenge for scanning transmission x-ray microscopes (STXM). The ultimate detector for the ALS STXMs should have a very high efficiency over a wide energy range, single photon counting capabilities up to 1GHz, high rejection of red laser light, fast response, and work in both vacuum and at atmospheric pressure. The results of an investigation using a photomultiplier tube (PMT) with a number of different scintillators are presented. The PMT is used in photon counting and analog modes. Scintillators used for this study include commercially available phosphor powders and various single crystals.

Unique Electron Polarimeter Analyzing Power Comparison And Precision Spin-Based Energy Measurement, J. Grames, C. K. Sinclair, J. Mitchell, E. Chudakov, H. Fenker, A. Freyberger, D.W. Higinbotham, M. Poelker, M. Steigerwald, M. Tiefenback, C. Cavata, S. Escoffier, F. Marie, T. Pussieux, P. Vernin, S. Danagoulian, V. Dharmawardane, R. Fatemi, K. Joo, M. Zeier, V. Gorbenko, R. Nasseripour, B. Raue, R. Suleiman, B. Zihlmann

United States Department of Energy: Publications

Precision measurements of the relative analyzing powers of five electron beam polarimeters, based on Compton, Møller, and Mott scattering, have been performed using the CEBAF accelerator at the Thomas Jefferson National Accelerator Facility (Jefferson Laboratory). A Wien filter in the 100 keV beam line of the injector was used to vary the electron spin orientation exiting the injector. High statistical precision measurements of the scattering asymmetry as a function of the spin orientation were made with each polarimeter. Since each polarimeter receives beam with the same magnitude of polarization, these asymmetry measurements permit a high statistical precision comparison of the …

Spin- And Angle-Resolved Spectroscopy Of S 2P Photoionization In The Hydrogen Sulfide Molecule, G. Turri, G. Snell, B. Langer, M. Martins, E. Kukk, S. E. Canton, R. C. Bilodeau, N. Cherepkov, John D. Bozek, A. L. D. Kilcoyne, N. Berrah

United States Department of Energy: Publications

Angle- and spin-resolved photoelectron spectroscopy with circularly and linearly polarized synchrotron radiation were used to study the electronic structure of the hydrogen sulfide molecule. A strong effect of the molecular environment appears in the spin-resolved measurements and, although less clearly, in the angular distribution of the sulfur 2 p photoelectrons. The anisotropy and spin parameters of the three main spectral components have been obtained. The validity of simple atomic models in explaining the results is discussed.

Methodology For Estimating Removable Quantities Of Agricultural Residues For Bioenergy And Bioproduct Use, Richard Nelson, Marie Walsh, John Sheehan, Robin Graham

United States Department of Energy: Publications

A methodology was developed to estimate quantities of crop residues that can be removed while maintaining rain or wind erosion at less than or equal to the tolerable soil-loss level. Six corn and wheat rotations in the 10 largest corn-producing states were analyzed. Residue removal rates for each rotation were evaluated for conventional, mulch/reduced, and no-till field operations. The analyses indicated that potential removable maximum quantities range from nearly 5.5 million dry metric t/yr for a continuous corn rotation using conventional till in Kansas to more than 97 million dry metric t/yr for a corn-wheat rotation using no-till in Illinois.

Heterotrophic Plate Count Bacteria—What Is Their Significance In Drinking Water?, Martin J. Allen, Stephen C. Edberg, Donald J. Reasoner

United States Environmental Protection Agency: Publications

While the literature documents the universal occurrence of heterotrophic plate count (HPC) bacteria in soils, foods, air, and all sources of water, there is a lingering question as to whether this group of organisms may signal an increased health risk when elevated populations are present in drinking water. This paper reviews the relevant literature on HPC bacteria in drinking water, the lack of clinical evidence that elevated populations or specific genera within the HPC flora pose an increased health risk to any segment of the population, and the appropriate uses of HPC data as a tool to monitor drinking water …

Nebraska Summary: S462 Case-Ih Jx85, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data. EXPLANATION OF THE TEST PROCEDURES Purpose The purpose of …

Engineering Mechanics Department Newsletter -- Winter 2004

Department of Engineering Mechanics: Information

Engineering Mechanics Hosts National Conference
Dzenis Awarded McBroom Professorship
EM Faculty News
EM Faculty Earn College Awards
EM Blackshirts
EM Mourns the Loss of Two Emeriti: Ralph Ekstrom 1923-2003 and Walter Erbach 1919-2003

High-Resolution Touch Sensor Could Be Boon To Cancer Surgeons, Others

Department of Chemical and Biomolecular Engineering: News Releases

Lincoln, Neb., June 8, 2006 -- One of the trickiest decisions facing a cancer surgeon today is where to stop cutting. The surgeon doesn't want to stop too soon and leave cancer cells in the patient's body, but he or she also doesn't want to take too many cells and do unnecessary damage to organs. That decision could soon be made much easier, though, thanks to a high-resolution touch sensor developed by chemical engineers at the University of Nebraska-Lincoln that may allow surgeons to tell at the level of a single layer of cells whether or not they have excised …

Orthogonal Spreading Sequences Constructed Using Hall’S Difference Set, Jennifer Seberry, Le Chung Tran, Yejing Wang, Beata J. Wysocki, Tadeusz Wysocki, Ying Zhao

Department of Electrical and Computer Engineering: Faculty Publications (to 2015)

In the paper we propose a new set of orthogonal spreading sequences based on the Hadamard matrix of order 32 constructed using the Hall difference set. The proposed sequences are characterised by low peaks in the aperiodic cross-correlation functions and have also good aperiodic auto-correlation properties.

Teaching Engineering Courses With Workbooks, Yaşar Demirel

Department of Chemical and Biomolecular Engineering: News Releases

Society expects that a modem college education will turn out students who are analytical. intellectually curious, culturally aware, employable, and capable of leadership. Some important skills needed for all degree programs are problem solving, communication (written and oral), team or group work, learning and information processing, and technology. Instructors feel rewarded and satisfied when they sense that they have made a difference in the life of a student.

Teaching Coupled Transport And Rate Processes, Yaşar Demirel

Department of Chemical and Biomolecular Engineering: News Releases

Coupling refers to a flux occurring without its primary thermodynamic driving force; for example, mass flux without a concentration gradient called the thermal diffusion is a well-known coupled process. Coupling also refers to a flux occurring in a direction opposite to the direction imposed by its driving force; for example, a mass flux can occur from a low to a high concentration region and is called the active transport or uphill transport, such as potassium and sodium pumps coupled to chemical energy released by the hydrolysis of adenosine triphosphate (ATP) in biological systems. Although the coupled processes seem to be …

Modified Convolutional Interleavers And Their Performance In Turbo Codes, Sina Vafi, Tadeusz Wysocki

Department of Electrical and Computer Engineering: Faculty Publications (to 2015)

In previous work,we have presented application of a model of the convolutional interleaver in turbo codes acting as a block interleaver through inserting a number of stuff bits equal to the number of interleaver memories at the end of each data 6lock.h order to get better turbo codes performance, the interleaver with larger period, which increases the number of stuff bits and educes effective channel bandwidth usage, has been suggested. In this paper, we introduce a modification to this interleaver improving turbo codes performance without increasing the interleaver period. This is carried out by increasing distance of adjacent bits that …

Two Complex Orthogonal Space-Time Codes For Eight Transmit Antennas, Le Chung Tran, J. Seberry, Yejing Wang, B. J. Wysocki, T. A. Wysocki, Tianbing Xia, Ying Zhao

Department of Electrical and Computer Engineering: Faculty Publications (to 2015)

Two new constructions of complex orthogonal space-time block codes of order 8 based on the theory of amicable orthogonal designs are presented and their performance compared with that of the standard code of order 8. These new codes are suitable for multi-modulation schemes where the performance can be sacrificed for a higher throughput.

The Effect Of Imperfect Carrier Recovery On The Performance Of The Diversity Antenna Selection Technique In Wireless Channels Utilizing Dstm, Le Chug Tran, Tadeusz Wysocki, Jennifer Seberry, Alfred Mertins

Department of Electrical and Computer Engineering: Faculty Publications (to 2015)

his paper examines the effect of imperfect carrier phase/frequency recovery at the receiver on the bit error performance of our diversity antenna selection technique (AST) proposed for channels utilizing Differential Space-Time Modulation (DSTM). The tolerance of differential detection associated with the proposed AST to phase/frequency errors is then analyzed.

Space Time Spreading With Modified Walsh-Hadamard Sequences, P Vial, B. J. Wysocki, I Raad, Tadeusz Wysocki

Department of Electrical and Computer Engineering: Faculty Publications (to 2015)

Previous work has shown that the performance of a Space Time Spreading (STS) system using walsh codes with two transmit antennas at the Base Station (BS) is degraded in the presence of mutual interference from adjacent sectors in the same cell. In this paper we use Modified Walsh-Hadamard sequences exhibiting improved cross-correlation performance, which potentially mitigates the effects of MA1 (Multiple Access Interference). The presented study also looks at variation of sets of different Modified Walsh- Hadamard codes being used by the adjacent interferer, with a hundred randomly selected pairings being chosen, as well as the case where one set …

Planetary Cliff Descent Using Cooperative Robots, Erik Mumm, Shane Farritor, Paola Pirjanian, Chris Leger, Paul Schenker

Department of Mechanical and Materials Engineering: Faculty Publications

Future robotic planetary exploration will need to traverse geographically diverse and challenging terrain. Cliffs, ravines, and fissures are of great scientific interest because they may contain important data regarding past water flow and past life.
Highly sloped terrain is difficult and often impossible to safely navigate using a single robot. This paper describes a control system for a team of three robots that access cliff walls at inclines up to 70°. Two robot assistants, or anchors, lower a third robot, called the rappeller, down the cliff using tethers. The anchors use actively controlled winches to first assist the rappeller in …

A Helical Tow Model And Numerical Simulation Of On-Line Thermal Curing Of Thermoset Composites In Filament Winding, Xuefeng Wang, David Y.S. Lou, Negli Zhang`

Department of Mechanical and Materials Engineering: Faculty Publications

A helical tow model of on-line curing of thermoset composites in winding is developed and solved numerically. Actual shape of tow in winding process is considered, and consequently, the modeling of the on-line curing process is more realistic. A numerical grid generation method is developed for the complicated geometry. Transformations of three-dimensional energy equation and its boundary conditions from physical domain to computational domain are performed, which are crucial in numerical grid generation method when an anisotropic medium is involved. A set of concise and regular equations is obtained. The numerical simulation results show that the helical tow model, in …

Safety Performance Evaluation Of The Nebraska Open Bridge Rail On An Inverted Tee Bridge Deck, Karla A. Polivka, John R. Rohde, Dean L. Sicking, Ronald K. Faller, James C. Holloway M.S.C.E., E.I.T.

Nebraska Department of Transportation: Research Reports

No abstract provided.

Policosanol Contents And Composition Of Grain Sorghum Kernels And Dried Distillers Grains, Keum T. Hwang, Curtis L. Weller, Susan L. Cuppett, Milford Hanna

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Grain sorghum can be a major source of policosanols, long-chained alcohols, that have beneficial physiological activities. Sorghum dried distillers grains (DDG), a by-product of ethanol production from grain sorghum. contain a large amount of policosanols. Content and composition of policosanols in long-chained lipids extracted from grain sorghum kernels and DDG were determined. Long-chained lipids were extracted using hot hexane or hot ethanol. The major components of the long-chained lipids extracted from grain sorghum kernels. as determined using HPLC were policosanols (37-44%), aldehydes (44-55%), and acids (4-5%). Long-chained lipids from DDG contained 52% policosanols, 23% aldehydes. 6.4% acids. and l7% wax …

Improving Heating Uniformity Of Fresh Fruit In Radio Frequency Treatments For Pest Control, Sohan Birla, Shaojin Wang, Juming Tang, Guy Hallman

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Non-uniform heating of fresh fruit caused by variations in radio frequency (RF) fields is a major obstacle in developing postharvest insect control treatments based on RF energy. A fruit mover was developed to evaluate possibilities to improve RF heating uniformity of large fruit, such as oranges and apples, in a 12 kW batch type RF system. This fruit mover provided a means to rotate and move fruit in water when subjected to RF heating. Parameters for moving and rotating fruit in the mover were selected based on consideration of vortex formation, foaming, damage to the fruit, and volume occupied by …

Acuta Enews January 2004, Vol. 33, No. 1

ACUTA Newsletters

ln This lssue

ACUTA to Offer Regional Workshops

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

ACUTA Announces Online Press Room

Board Report.................... Carmine Piscopo, Providence College

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

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

WLNP........................... Greg Stahl, St. Lawrence University

Thanks to Journal Advertisers for '03

Welcome New Members

Human Performance Reliability: On-Line Assessment Using Fuzzy Logic, William J. Kolarik, Jeffrey C. Woldstad, Susan Lu, Huitian Lu

Department of Industrial and Management Systems Engineering: Faculty Publications

This paper presents an on-line approach to monitoring human performance in terms of conditional reliability when one is performing a task. Unlike traditional human reliability analysis, this approach develops a dynamic model that is able to cope with constantly changing conditions that affect operator performance. A fuzzy knowledge-based assessment approach is developed in order to deal with uncertainty and subjectivity associated with human performance assessment. This technology includes three main parts/functions: (i) on-line performance monitoring; (ii) real-time performance forecasting; and (iii) performance reliability assessment. The technology is demonstrated in real-time and provides timely conditioned reliability information regarding task success/failure. In …

Complex Orthogonal Sequences From Amicable Hadamard Matrices, L. C. Tran, J. Seberry, B. J. Wysocki, Tadeusz Wysocki, T. Xia, Ying Zhao

Department of Electrical and Computer Engineering: Faculty Publications (to 2015)

The paper deals with the novel technique of designing complex spreading sequences with only four phases (0.25π, 0.75π, 1.25π, 1.75π). The interesting feature of those new sequences is the fact that not only the complex sequences are orthogonal but the real parts and imaginary parts are independently orthogonal. This can be utilized for spreading of complex constellation signals where the independent spreading using bipolar sequences (real part for in-phase component and imaginary part for quadrature component) can be applied. The paper introduces the theoretical background, and some example constructions of the amicable …