Digital Commons Network^™

Assessment Of Concentrated Flow Through Riparian Buffers, Michael G. Dosskey, Matthew J. Helmers, Dean E. Eisenhauer, Thomas G. Franti, Kyle D. Hoagland

Matthew J. Helmers

Concentrated flow of surface runoff from agricultural fields may limit the capability of riparian buffers to remove pollutants. This study was conducted on four farms in southeastern Nebraska to develop a method for assessing the extent of concentrated flow in riparian buffers and for evaluating the impact that it has on sediment-trapping efficiency. Field methods consisted of mapping field runoff areas and their pathways to and through riparian buffers to streams. Mathematical relationships were developed from a model (VFSMOD) that estimates sediment-trapping efficiency from the ratio of buffer area to field runoff area. Among the farms surveyed, riparian buffers averaged …

Systematic Microstructure Variability In Double-Diffusively Stable Coastal Waters Of Nonuniform Density Gradient, Timothy F. Duda, Chris R. Rehmann

Chris R. Rehmann

Conductivity microstructure, water velocity, and stratification were measured during a tow-yo transect near the New England shelf/slope front in early August 1997. Velocity data were collected with an acoustic Doppler profiler on the ship. The other data were collected with a towed platform. Estimates of χ, the rate of dissipation of temperature variance, were computed from the conductivity data with vertical resolution of 0.3 m. Relationships between χ and shear, temperature gradient, buoyancy frequency (N), and gradient Richardson number (Ri) were explored, with special focus on measurements taken in waters stable to double-diffusive processes (to avoid ambiguity of interpretation) and …

Time Management—A Design-Build Builder's Perspective, Srinath Pai Kasturi, Douglas D. Gransberg

Douglas D. Gransberg

Time management in design-build construction encompasses efficient project management controls, scheduling and execution of the contract as agreed upon by the parties. Time management is one of the prime areas of concern to the builder and his team. It plays an important role in shaping the progress of projects and thus is decisive in determining its course. This article explains the importance of time management in construction. Time management techniques on a (builder prime, architect subcontract) design build project from a builders perspective are presented. The builder ideally has to prioritize his tasks based on the resources and manpower of …

Thermodynamic Behavior Of Poly(Cyclohexylethylene) In Polyolefin Diblock Copolymers, Eric W. Cochran, Frank S. Bates

Eric W. Cochran

We report the temperature dependence of the Flory-Huggins interaction parameter for three symmetric diblock copolymer systems containing poly(cyclohexylethylene) (PCHE): poly(cyclohexylethylene-b-ethylene) (CE), poly(cyclohexylethylene-b-ethylethylene) (CEE), and poly(cyclohexylethylene-b-ethylenepropylene) (CP). Order-disorder transition temperatures (TODT) were determined using dynamic mechanical spectroscopy and interpreted with mean-field theory, (χN)ODT = 10.5, leading to well-defined expressions for χ(T). These results have been analyzed in the context of solubility parameter (δ) theory resulting in a unique parameter δC that describes the interactions in CE, CP, and CEE, where δC < δEE < δP < δE with (δE - δC) ≈ 1.6 MPa1/2 at 500 K. In contrast to the predictions of group contribution theory, this indicates that δC is in surprisingly close proximity to the solubility parameter for poly(dimethylsiloxane).

Magnetochemical Origin For Invar Anomalies In Iron-Nickel Alloys, V. Crisan, P. Entel, H. Ebert, H. Akai, Duane D. Johnson, J. B. Staunton

Duane D. Johnson

Zero- and finite-temperature (T) first-principles calculations versus composition (c) show that magnetochemical effects lead to Invar anomalies in Fe-(Ni, Co, Pt) alloys. Chemical short- or long-range order and negative interatomic exchange interaction of electrons in antibonding majority-spin states force the face-centered-cubic lattice to compete simultaneously for a smaller volume (from antiferromagnetic tendencies) and a larger volume (from Stoner ferromagnetic tendencies). The resulting additional negative lattice anharmonicity is very large for Fe-(Ni, Co) while absent for Fe-Pt. Our results explain the T- and c-dependent behavior of Invar properties, including the lattice softening and thermal expansion of Fe-Ni. In addition, the occurrence …

Hyperspectral Imagery For Various Crop Growth Information Extraction, Haibo Yao, Lei Tian, Marvin Paulsen, Amy L. Kaleita, Mukti Singh

Amy L. Kaleita

Aerial hyperspectral imagery has potential for agriculture applications. The objective of this study is to identify significant wavelength ranges (image bands or band combinations) from hyperspectral imagery for different field information extraction. The field information include corn nitrogen content, plant population, yield, and grain quality such as oil, protein, and extractable starch. All the images were processed using the GA-SPCA (Genetic Algorithm based Selective Principal Component Analysis) method . T he GA-SPCA method can filter out significant image bands and reduce the image data dimension to only one principle component image through a cascade two-step dimension reduction process. It was …

Remote Sensing Of Site-Specific Soil Characteristics For Precision Farming, Amy L. Kaleita, Lei F. Tian

Amy L. Kaleita

A methodology for assessing distributed surface soil moisture content from optical remote sensing is developed. This study uses both ground-based and remotely sensed spectral measurements of soil reflectance in visible and near-infrared wavelengths and concurrent measurements of volumetric soil moisture within the top 6 cm to establish a relationship between spectral response and moisture. Various approaches, including principal component analyses and regression techniques are investigated to determine the potential for quantifying soil moisture from the spectral reflection data. Preliminary investigations have yielded R 2 values as high as 0.62 when comparing predictions to actual moisture values. Investigation of predicting soil …

Remote Sensing Of Site-Specific Soil Characteristics For Precision Farming, Amy L. Kaleita, Lei Tian

Amy L. Kaleita

A methodology for assessing distributed surface soil moisture content from optical remote sensing is developed. This study uses both ground-based and remotely sensed spectral measurements of soil reflectance in visible and near-infrared wavelengths and concurrent measurements of volumetric soil moisture within the top 6 cm to establish a relationship between spectral response and moisture. Various approaches, including principal component analyses and regression techniques are investigated to determine the potential for quantifying soil moisture from the spectral reflection data. Preliminary investigations have yielded R 2 values as high as 0.62 when comparing predictions to actual moisture values. Investigation of predicting soil …

Screening For Volatile Fatty Acids In Agricultural Air Using Solid Phase Microextraction And Gas Chromatography – Mass Spectrometry, Jarett P. Spinhirne, Jacek A. Koziel, David B. Parker, Darren L. Williams, N. Andy Cole, John M. Sweeten

Jacek A. Koziel

Volatile fatty acids (VFAs) are a major component of odorous gases associated with agricultural sources. Because of typically low VFA air concentrations, conventional air sampling methods including sorbent tubes and vacuum canisters are often not sensitive enough to detect them. Solid phase microextraction (SPME) was used in this research because it is very sensitive, reusable, fast, and combines sampling and sample preparation, allowing for rapid detection of low concentrations of organics in air. This research focused on 7 VFAs: acetic, propionic, isobutyric, butyric, isovaleric, valeric, and hexanoic acids. Field experiments were conducted to test this method for air sampling of …

Noninvasive Sampling And Analysis Of Bovine Breath Using Solid-Phase Microextraction And Gas Chromatography-Mass Spectrometry: A Feasibility Study, Jacek A. Koziel, Jarett P. Spinhirne, Norbert K. Chirase

Jacek A. Koziel

An experiment was conducted to examine the feasibility of detecting unique volatile organic biomarkers exhaled by healthy and morbid heifer calves on-site using noninvasive sampling with solid phase microextraction (SPME) and analysis with gas chromatography-mass spectrometry (GC-MS). Two heifers were selected on the bases of health status and were sampled from 5 to 15 min with a special facemask sampling system using DVB/Carboxen/PDMS 50/30 µ m and PDMS 100 µ m SPME fibers. The samples were sealed and transported to the laboratory and analyzed with ion trap GC-MS. Acetone, methyl ethyl ketone, toluene, pentadecane, and nonanal were detected in cattle …

Hyperspectral Imagery For Various Crop Growth Information Extraction, Haibo Yao, Lei Tian, Marvin Paulsen, Amy Kaleita, Mukti Singh

Amy L. Kaleita

Aerial hyperspectral imagery has potential for agriculture applications. The objective of this study is to identify significant wavelength ranges (image bands or band combinations) from hyperspectral imagery for different field information extraction. The field information include corn nitrogen content, plant population, yield, and grain quality such as oil, protein, and extractable starch. All the images were processed using the GA-SPCA (Genetic Algorithm based Selective Principal Component Analysis) method . T he GA-SPCA method can filter out significant image bands and reduce the image data dimension to only one principle component image through a cascade two-step dimension reduction process. It was …

An Overland Flow Sampler For Use In Vegetative Filters, D. Eisenhauer, Matthew J. Helmers, J. Brothers, M. Dosskey, T. Franti, A. Boldt, B. Strahm

Matthew J. Helmers

Vegetative filters (VF) are used to remove contaminants from agricultural runoff and improve surface water quality. State and federal cost-share funds are available to encourage landowners to install VF. The USDA-National Conservation Buffer Initiative calls for 3.2 million km of buffers to be installed by the year 2002. Numerous experimental plot and modeling studies have quantified the removal of sediments and other non-point source (NPS) contaminants from agricultural runoff by VF. Almost all of these studies have been conducted under controlled settings, including artificial sheet flow conditions, and using expensive, labor-intensive measurement systems. There is a critical need for simple, …

Outcomes Assessment: Developing An Electronic Assessment Database As A Model For Collection And Analysis Of Data, Joni E. Spurlin, Sarah A. Rajala, Jerome P. Lavelle, O. Jerome Hoskins

Sarah A. Rajala

As the ABET process in each institution moves toward outcomes assessment, it pushes each program to develop and implement its outcome assessment plans. Assessment plans document how programs will gather data, interpret the findings, and use the results to make improvements in programs, curricula, and resources. The ABET team at North Carolina State University (faculty from each engineering discipline along with assessment-knowledgeable personnel) has developed a model that academic programs within the College of Engineering use to determine what data to gather, where to obtain the data, and what criteria may be most appropriate when interpreting the data. This paper …

Width-Wise Variation Of Magnetic Tape Pack Stresses, Jonathan A. Wickert, Y.M. Lee

Jonathan A. Wickert

A model is developed for predicting the stress and displacement fields within a magnetic tape pack, where those quantities are allowed to vary in both the pack's radial and transverse (cross-tape) directions. As has been the case in previous analyses based upon one-dimensional wound roll models, the present approach accounts for the anisotropic and nonlinear constitutive properties of the layered tape, and the incremental manner in which the pack is wound. Further, such widthwise variation effects as differential hub compliance and nonuniform winding tension, which can be significant in data cartridge design, are also treated in the model. The pack …

A Time-Resolved Method For Nonlinear Acoustic Measurement, Stephen D. Holland

Stephen D. Holland

We describe a time-resolved method for measuring nonlinear ultrasonic phenomena. Conventional approaches to the measurement of nonlinear phenomena utilize narrowband measurements of harmonic generation. These measurements are fundamentally narrowband and hence have poor time resolution. In contrast, our method utilizes a series of narrowband bursts that can be combined to form a composite time-resolved broadband impulse. Simultaneous time resolution and harmonic isolation are thereby obtained. The composite impulse can then be used to perform time-resolved measurements of weakly nonlinear phenomena. Such time-resolved measurements have the potential to dramatically improve the capability and performance of nondestructive testing systems that use acoustic …

Absolute Tin(111) Step Energies From Analysis Of Anisotropic Island Shape Fluctuations, S. Kodambaka, V. Petrova, S. V. Khare, Duane D. Johnson, I. Petrov, J. E. Greene

Duane D. Johnson

In situ high-temperature (1165–1248 K) scanning tunneling microscopy was used to measure fluctuations around the equilibrium shape of two-dimensional vacancy islands on TiN(111) terraces. From the equilibrium shape, the ratio of the two ⟨110⟩ step energies was found to be 0.72±0.02. Combining this with the results of an exact approach for analysis of shape fluctuations, applicable to highly anisotropic islands, we obtain absolute values for step energies and step stiffnesses as a function of orientation.

Toward Improved Film Cooling Prediction, G. Medic, Paul A. Durbin

Paul A. Durbin

Computations of flow and heat transfer for a film-cooled high pressure gas turbine rotor blade geometry are presented with an assessment of several turbulence models. Details of flow and temperature field predictions in the vicinity of cooling holes are examined. It is demonstrated that good predictions can be obtained when spurious turbulence energy production by the turbulence model is prevented.

Toward Improved Prediction Of Heat Transfer On Turbine Blades, G. Medic, Paul A. Durbin

Paul A. Durbin

Reynolds averaged computations of turbulent flow in a transonic turbine passage are presented to illustrate a manner in which widely used turbulence models sometimes provide poor heat transfer predictions. It is shown that simple, physically and mathematically based constraints can substantially improve those predictions.

Multipole Expansion Of Dislocation Interactions: Application To Discrete Dislocations, Richard Alan Lesar, J. M. Rickman

Richard Alan Lesar

The interaction between dislocations is long ranged and anisotropic, leading to severe computational challenges for large-scale simulations. Here we present a multipolar expansion for the interaction energy between dislocations in three dimensions, based on a straightforward expansion of some familiar energy expressions. An evaluation of the needed line integrals is conveniently performed by numerical integration over parametric representations of the dislocation loops. We show that the multipole expansion converges very quickly, leading to potential savings in computational time for evaluating dislocation interactions.

Modeling Vegetative Filter Performance With Vfsmod, Matthew J. Helmers, Dean E. Eisenhauer, Michael G. Dosskey, Thomas G. Franti

Matthew J. Helmers

The model VFSMOD was used to investigate the effect of varying watershed characteristics and buffer dimensions on the sediment trapping efficiency of vegetative filters. This investigation allows for a better understanding of how watershed characteristics, buffer dimensions, and storm characteristics impact the performance of vegetative filters. Using VFSMOD, relationships that estimate sediment trapping efficiency from the ratio of filter area and field area were developed for different sites. These relationships have been applied for field assessment of concentrated flow.

Stress Field In Finite Width Axisymmetric Wound Rolls, Jonathan A. Wickert, Y.M. Lee

Jonathan A. Wickert

A model is developed for predicting the stress field within a wound roll of web material, in which the radial, circumferential, transverse, and shear stresses can vary in both the roll's radial and cross-web (transverse) directions. As has been the case in previous wound roll stress analyses based on one-dimensional models, the present approach accounts for the anisotropic and nonlinear material properties of the layered web material, and the incremental manner in which the roll is wound. In addition, the present development accounts for arbitrary cross-sectional geometry and material of the core, and the presence of nonuniform tension across the …

Low-Pressure Phase Transformation From Rhombohedral To Cubic Bn: Experiment And Theory, Valery I. Levitas, Leonid K. Shvedov

Valery I. Levitas

An irreversible phase transformation (PT) from the rhombohedral phase of boron nitride rBN to cubic cBN was recently recorded at the surprisingly low pressure of 5.6 GPa at room temperature. In this paper, a very nontrivial and unexpected explanation of this phenomenon is found, based on our criterion for the PT in plastic materials and approximate solution of corresponding plastic problems. It is found that due to orientational plastic instability and rotational softening in rBN and the higher yield stress of cBN, stresses grow drastically in the transforming region during the PT (despite a volume decrease by a factor of …

First-Principles Theory Of The Temperature And Compositional Dependence Of Atomic Short-Range Order In Disordered Cu-Pd Alloys, R. V. Chepulskii, J. B. Staunton, Ezio Bruno, B. Ginatempo, Duane D. Johnson

Duane D. Johnson

We combine the first-principles, Korringa-Kohn-Rostoker coherent potential approximation based calculations of compositional fluctuations with a statistical mechanical ring approximation to study the temperature (T) and composition (c) dependence of the atomic short-range order (SRO) in disordered, face-centred cubic, Cu-Pd alloys. The fourfold splitting of SRO peaks around the equivalent X(0,1,0) points in reciprocal space is obtained in a wide T−c region. Such splitting is shown to be an “energy” effect caused by the absolute minima of the Fourier transform of the effective atomic interactions and related previously to the existence of nested sheets of the disordered alloy’s Fermi surface. However, …

Utilizing The Internet To Improve Student Learning In A First Course In Engineering Economy With Real-World Unsolved Problems In Collaboration With Industry, Janis P. Terpenny, William G. Sullivan, Harpreet Singh, Kimberly Sward

Janis P. Terpenny

This paper reports on results of an experiment to investigate whether technology and the Internet facilitate student learning of Engineering Economy through real world problems in collaboration with industry. An overview of the organization and administration of the collaborative projects is presented. Learning aids and Internet tools are included in this discussion. Assessment results of student performance and perception are also presented. It was found using a bootstrap sample, at a significance level of 0.05, that the grade point average (GPA) of students working on projects in collaboration with industry administered through a variety of tools over the Internet (Experimental …

Three-Dimensional Landau Theory For Multivariant Stress-Induced Martensitic Phase Transformations. Ii. Multivariant Phase Transformations And Stress Space Analysis, Valery I. Levitas, Dean L. Preston

Valery I. Levitas

In this paper, the three-dimensional Landau model of austenite-martensite transformations constructed in Part I is generalized to include transformations between an arbitrary number of martensitic variants. The model can incorporate all temperature-dependent thermomechanical properties of both phases for arbitrary crystal symmetries, including higher-order elastic constants, and it correctly describes the characteristic features of stress-strain curves for shape-memory alloys and steels, namely, constant transformation strain tensors, constant or weakly temperature dependent stress hysteresis, and transformation at nonzero tangent moduli. Geometric representations of the conditions for phase equilibrium and phase transformations in six-dimensional stress space are developed. For the cubic-tetragonal phase transformation, …

Three-Dimensional Landau Theory For Multivariant Stress-Induced Martensitic Phase Transformations. I. Austenite↔Martensite, Valery I. Levitas, Dean L. Preston

Valery I. Levitas

A three-dimensional Landau theory of stress-induced martensitic phase transformations is presented. It describes transformations between austenite and martensitic variants and transformations between martensitic variants. The Landau free energy incorporates all temperature-dependent thermomechanical properties of both phases. The theory accounts for the principal features of martensitic transformations in shape memory alloys and steels, namely, stress-strain curves with constant transformation strain and constant, or weakly temperature dependent, stress hysteresis, as well as nonzero tangent elastic moduli at the phase transformation point. In part I, the austenite↔martensite phase transformation is treated, while transformations between martensitic variants are considered in part II.

Integrating Critical Information On Flight Deck Displays, Patricia May Ververs, Michael C. Dorneich, Michael D. Good, Joshua Lee Downs

Michael C. Dorneich

Honeywell Laboratories has developed a concept for integrating multiple sources of data concerning information outside the aircraft. The concept, ANCOA (Alerting and Notification for Conditions Outside the Aircraft), was conceived as means for reducing error conflicts and establishing a clear prioritization among currently independent and disparate alerting systems for hazards external to the aircraft (e.g., TCAS, EGPWS). This paper documents an empirical evaluation of ANCOA by 12 professional pilots. The concept was evaluated in Honeywell Laboratories’ Flight Simulation Laboratory in Minneapolis, Minnesota. Two core ANCOA features were manipulated and compared. The first was the integration of information by comparing ANCOA’s …

Low-Cost Manufacturing Process For Nanostructured Metals And Alloys, Travis L. Brown, Srinivasan Swaminathan, Srinivasan Chandrasekar, W. Dale Compton, Alexander H. King, Kevin P. Trumble

Alexander H. King

In spite of their interesting properties, nanostructured materials have found limited uses because of the cost of preparation and the limited range of materials that can be synthesized. It has been shown that most of these limitations can be overcome by subjecting a material to large-scale deformation, as occurs during common machining operations. The chips produced during lathe machining of a variety of pure metals, steels, and other alloys are shown to be nanostructured with grain (crystal) sizes between 100 and 800 nm. The hardness of the chips is found to be significantly greater than that of the bulk material.

Piezoelectric In Situ Transmission Electron Microscopy Technique For Direct Observations Of Fatigue Damage Accumulation In Constrained Metallic Thin Films, Xiaoli Tan, T. Du, J.K. Shang

Xiaoli Tan

A piezoelectricin situtransmission electron microscopy(TEM) technique has been developed to observe the damage mechanism in constrained metallic thin films under cyclic loading. The technique was based on the piezoelectric actuation of a multilayered structure in which a metallic thin film was sandwiched between a piezoelectric actuator and a silicon substrate. An alternating electric field with a static offset was applied on the piezoelectric actuator to drive the crack growth in the thin metallic layer while the sample was imaged in TEM. The technique was demonstrated on solder thin films where cavitation was found to be the dominant fatigue damage mechanism.

Estrogen Concentrations In Dairy And Swine Waste Storage And Treatment Structures In And Around Tennessee, D. Raj Raman, Elizabeth L. Williams, Robert T. Burns, Alice C. Layton, Adam S. Daugherty, Michael D. Mullen

D. Raj Raman

Naturally occurring estrogens in animal wastes may cause negative environmental impacts in some watersheds. However, there is little published data regarding the concentrations of these estrogenic compounds in full-scale animal waste treatment and storage structures, thus making risk assessment difficult. To address this knowledge gap, the research described in this paper explores estrogen concentrations in 19 animal waste storage and treatment structures at dairy and swine production facilities in and around Tennessee.

Samples have been collected from eight dairy and eleven swine facilities, representing a range of waste storage and treatment structures typical of Tennessee, and much of the southeastern …