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Articles 1 - 16 of 16
Full-Text Articles in Engineering
Determination Of Plate Source, Detector Separation From One Signal, Stephen D. Holland, Tadej Kosel, Richard Weaver, Wolfgang Sachse
Determination Of Plate Source, Detector Separation From One Signal, Stephen D. Holland, Tadej Kosel, Richard Weaver, Wolfgang Sachse
Stephen D. Holland
We address the problem of locating a transient source, such as an acoustic emission source, in a plate. We apply time-frequency analysis to the signals detected at a receiver. These highly dispersive and complex waveforms are measured for source-receiver separations ranging from 40 to 180 plate thicknesses and at frequencies such that ten to twenty Rayleigh-Lamb branches are included. Re-assigned, smoothed, pseudo-Wigner-Ville distributions are generated that exhibit the expected sharp ridges in the time-frequency plane, lying along the predicted frequency-time-of-arrival relations. The source-receiver separation can be determined from such plots.
Measuring Partnered Project Performance, Douglas D. Gransberg, Howard L. Reynolds, Jack Boyd
Measuring Partnered Project Performance, Douglas D. Gransberg, Howard L. Reynolds, Jack Boyd
Douglas D. Gransberg
The results of a study of over 400 projects completed by the Texas Department of Transportation over 5 years are presented. The objective was to compare the performance of construction projects on which formal partnering agreements had been executed with projects that had been completed without partnering and measure the benefits due to partnering. The data was collected by 20 different aspects, from cost and time growth to the amount of previous experience.
Solid-Liquid Phase Equilibrium For Binary Lennard-Jones Mixtures, Monica R. Hitchcock, Carol K. Hall
Solid-Liquid Phase Equilibrium For Binary Lennard-Jones Mixtures, Monica R. Hitchcock, Carol K. Hall
Monica H. Lamm
Solid-liquid phase diagrams are calculated for binary mixtures of Lennard-Jones spheres using Monte Carlo simulation and the Gibbs-Duhem integration technique of Kofke. We calculate solid-liquid phase diagrams for the model Lennard-Jones mixtures: argon-methane, krypton-methane, and argon-krypton, and compare our simulation results with experimental data and with Cottin and Monson's recent cell theory predictions. The Lennard-Jones model simulation results and the cell theory predictions show qualitative agreement with the experimental phase diagrams. One of the mixtures, argon-krypton, has a different phase diagram than its hard-sphere counterpart, suggesting that attractive interactions are an important consideration in determining solid-liquid phase behavior. We then …
Introduction To Engineering Problem Solving—A New Course For 1100 First Year Engineering Students, Richard L. Porter, Laura J. Bottomley, Mary Clare Robbins, Walthea V. Yarbrough, Sarah A. Rajala, Hugh Fuller
Introduction To Engineering Problem Solving—A New Course For 1100 First Year Engineering Students, Richard L. Porter, Laura J. Bottomley, Mary Clare Robbins, Walthea V. Yarbrough, Sarah A. Rajala, Hugh Fuller
Sarah A. Rajala
During the past several years, NC State University has offered several experimental courses designed for the first year student in engineering; IMPEC, an integrated approach to mathematics, physics, engineering, and chemistry; E123, a mechanical dissection course which is now linked with the first year writing and composition course; and ECE 292D, a hands-on team based design course offered to upper class students as well. All were offered as an alternative to the introductory course (E100) that had little academic content, no engineering problem solving, and consisted of a large lecture room format with information dissemination as the major goal. Although …
Novel One-Phase Synthesis Of Thiol-Functionalized Gold, Palladium, And Iridium Nanoparticles Using Superhydride, Chanel K. Yee, Rainer Jordan, Abraham Ulman, Henry White, Alexander H. King, Miriam Rafailovich, Jonathan Sokolov
Novel One-Phase Synthesis Of Thiol-Functionalized Gold, Palladium, And Iridium Nanoparticles Using Superhydride, Chanel K. Yee, Rainer Jordan, Abraham Ulman, Henry White, Alexander H. King, Miriam Rafailovich, Jonathan Sokolov
Alexander H. King
A new, facile, general one-phase synthesis for thiol-functionalized gold, palladium, and iridium nanoparticles, using tetrahydrofuran (THF) as the solvent and lithium triethylborohydride (Superhydride) as the reducing agent, is presented. For octadecanethiol-functionalized gold (Au/ODT) nanoparticles, HRTEM of drop-cast particle-films revealed the formation of spherical particles of d = 4 ± 0.3 nm average size. Electron diffraction shows fcc packing arrangement, similar to that of bulk gold. The crystalline gold cores are surrounded with closely packed n-alkyl chains mainly in an all-trans conformation, adopting orthorhombic packing as confirmed by FTIR spectroscopy. Particles are arranged in a discrete solidlike assembly with a correlation …
Incommensurate And Commensurate Antiferromagnetic Spin Fluctuations In Cr And Cr Alloys From Ab Initio Dynamical Spin Susceptibility Calculations, Duane D. Johnson, J. Pulter, B. Ginatempo, E. Bruno, J. B. Staunton
Incommensurate And Commensurate Antiferromagnetic Spin Fluctuations In Cr And Cr Alloys From Ab Initio Dynamical Spin Susceptibility Calculations, Duane D. Johnson, J. Pulter, B. Ginatempo, E. Bruno, J. B. Staunton
Duane D. Johnson
A scheme for making ab initio calculations of the dynamic paramagnetic spin susceptibilities of solids at finite temperatures is described. It is based on time-dependent density functional theory and employs an electronic multiple scattering formalism. Incommensurate and commensurate antiferromagnetic spin fluctuations in paramagnetic Cr and compositionally disordered Cr95V5 and Cr95Re5 alloys are studied together with the connection with the nesting of their Fermi surfaces. We find that the spin fluctuations can be described rather simply in terms of an overdamped oscillator model. Good agreement with inelastic neutron scattering data is obtained.
Facial Features Localization In Front View Head And Shoulders Images, Adnan M. Alattar, Sarah A. Rajala
Facial Features Localization In Front View Head And Shoulders Images, Adnan M. Alattar, Sarah A. Rajala
Sarah A. Rajala
The computerized process of locating human facial features such as the eyes, nose and mouth in a head and shoulders image is crucial to such applications as automatic face identification and model-based video coding. A new model-based algorithm for locating these major features is developed. The algorithm estimates the parameters of the ellipse which best fits the head view in the image and uses these parameters to calculate the estimated locations of the facial features. It then refines the estimated coordinates of the eyes, mouth, and nose by exploiting the vertical and horizontal projections of the pixels in windows around …
Damper For Brake Noise Reduction, Jonathan A. Wickert, Adnan Akay
Damper For Brake Noise Reduction, Jonathan A. Wickert, Adnan Akay
Jonathan A. Wickert
An apparatus for reducing unwanted brake noise has a ring damper affixed around a periphery of a brake rotor in a disk brake system in a manner that permits relative motion and slippage between the ring damper and the rotor when the rotor vibrates during braking. In a preferred embodiment, the ring damper is disposed in a groove formed in the periphery of the disk and is pre-loaded against the rotor both radially and transversely. The ring damper is held in place by the groove itself and by the interference pre-load or pretension between the ring damper and the disk …
Resistivity, Thermopower And The Correlation To Infrared Active Vibrations Of Mn1.56co0.96ni0.48o4 Spinel Films Sputtered In An Oxygen Partial Pressure Series, Rand Dannenberg, S. Baliga, R. J. Gambino, Alexander H. King, A. P. Doctor
Resistivity, Thermopower And The Correlation To Infrared Active Vibrations Of Mn1.56co0.96ni0.48o4 Spinel Films Sputtered In An Oxygen Partial Pressure Series, Rand Dannenberg, S. Baliga, R. J. Gambino, Alexander H. King, A. P. Doctor
Alexander H. King
Mn1.56Co0.96Ni0.48O4 spinel was sputter deposited using a series of oxygen partial pressures. Electrical resistivity versus temperature and thermopower versus temperature measurements at each oxygen partial pressure were made. The variations of the thermopower and resistivity with oxygen partial pressure are consistent with a change in the ratio of Mn3+ to Mn4+ cations, which occurs due to changes of oxygen content of the material. The weak temperature dependence of the thermopower indicates small polaron hopping is the charge transport mechanism. Combining the models of Mott and Schnakenberg to analyze the transport data, we find that the Debye temperature (or frequency) is …
Characterization Of Oxidation Products Of Tnt Metabolism In Aquatic Phytoremediation Systems Of Myriophyllum Aquaticum, R. Bhadra, R. J. Spanggord, D. G. Wayment, J. B. Hughes, Jacqueline V. Shanks
Characterization Of Oxidation Products Of Tnt Metabolism In Aquatic Phytoremediation Systems Of Myriophyllum Aquaticum, R. Bhadra, R. J. Spanggord, D. G. Wayment, J. B. Hughes, Jacqueline V. Shanks
Jacqueline V. Shanks
TNT transformation processes in sediment-free, “natural”, aquatic phytoremediation systems of Myriophyllum aquaticum were investigated with specific interest in oxidation products. Extraction procedures combining liquidliquid extractions and solid-phase extractions were developed for the isolation of the mostly acidic, oxidized TNT metabolites. Six compounds unique from the reduction products of TNT were isolated and characterized by UVvis, 1H, and 13C NMR spectroscopy, by mass spectroscopy, and by chemical synthesis where feasible. These compounds include 2-amino-4,6-dinitrobenzoic acid, 2,4-dinitro-6- hydroxy-benzyl alcohol, 2-N-acetoxyamino-4,6-dinitrobenzaldehyde, 2,4-dinitro-6-hydroxytoluene, and two binuclear metabolites unique from the customary azoxytetranitrotoluenes. The monoaryl compounds show clear evidence of oxidative transformations, methyl oxidation and/or …
Minimum Error Fickian Diffusion Coefficients For Mass Diffusion In Multicomponent Gas Mixtures, Shankar Subramaniam
Minimum Error Fickian Diffusion Coefficients For Mass Diffusion In Multicomponent Gas Mixtures, Shankar Subramaniam
Shankar Subramaniam
Mass diffusion in multicomponent gas mixtures is governed by a coupled system of linear equations for the diffusive mass fluxes in terms of thermodynamic driving forces, known as the generalized Stefan–Maxwell equation. In computations of mass diffusion in multicomponent gas mixtures, this coupling between the different components results in considerable computational overhead. Consequently, simplified diffusion models for the diffusive mass fluxes as explicit functions of the driving forces are an attractive alternative. These models can be interpreted as an approximate solution to the Stefan–Maxwell equation. Simplified diffusion models require the specification of “effective” diffusion coefficients which are usually expressed as …
Magnetic Resonance Imaging Analysis Of Molecular Mobility During Dissolution Of Poly(Vinyl Alcohol) In Water, Balaji Narasimhan, J. E.M. Snaar, R. W. Bowtell, S. Morgan, C. D. Melia, N. A. Peppas
Magnetic Resonance Imaging Analysis Of Molecular Mobility During Dissolution Of Poly(Vinyl Alcohol) In Water, Balaji Narasimhan, J. E.M. Snaar, R. W. Bowtell, S. Morgan, C. D. Melia, N. A. Peppas
Balaji Narasimhan
Magnetic resonance imaging is used to study changing microstructure and molecular motion during dissolution of poly(vinyl alcohol) (PVA) in water. One-dimensional water concentration profiles were measured as a function of distance from the polymer-solvent interface. Diffusion-weighted profiles were used to calculate the spatial variation of the self-diffusion coefficient of water. The results indicate that diffusion coefficient values decrease toward the glassy core of the polymer. Self-diffusion coefficient values within the dissolving polymer increase with increasing dissolution time, while those near the polymer-solvent interface remain fairly constant. The effect of PVA molecular weight on the dissolution mechanism was investigated, with MÌ„n …
Infrared Optical Properties Of Mn1.56co0.96ni0.48o4 Spinel Films Sputter Deposited In An Oxygen Partial Pressure Series, Rand Dannenberg, S. Baliga, R. J. Gambino, Alexander H. King, A. P. Doctor
Infrared Optical Properties Of Mn1.56co0.96ni0.48o4 Spinel Films Sputter Deposited In An Oxygen Partial Pressure Series, Rand Dannenberg, S. Baliga, R. J. Gambino, Alexander H. King, A. P. Doctor
Alexander H. King
Mn1.56Co0.96Ni0.48O4 spinel films were sputter deposited onto silicon substrates using a series of oxygen partial pressures. Fourier transform infrared transmission and reflectance, and Raman scattering measurements were made. The 1–25 μm wavelength range was examined using these optical techniques. The complex index of refraction was calculated for this entire wavelength range. Infrared active vibrations were analyzed using multiple oscillator analysis, Kramers–Kronig analysis, and derivative reflectance spectroscopy. The Raman and infrared active lattice vibrations were observed to shift with increasing oxygen partial pressure during film deposition, and were consistent with the earlier published shift in Debye frequency calculated from resistivity data. …
Error Analysis For The Numerical Evaluation Of The Diagonal Forms Of The Scalar Spherical Addition Theorem, S. Koc, Jiming Song, W. C. Chew
Error Analysis For The Numerical Evaluation Of The Diagonal Forms Of The Scalar Spherical Addition Theorem, S. Koc, Jiming Song, W. C. Chew
Jiming Song
The numerical solution of wave scattering from large objects or from a large cluster of scatterers requires excessive computational resources and it becomes necessary to use approximate -but fast - methods such as the fast multipole method; however, since these methods are only approximate, it is important to have an estimate for the error introduced in such calculations. An analysis of the error for the fast multipole method is presented and estimates for truncation and numerical integration errors are obtained. The error caused by polynomial interpolation in a multilevel fast multipole algorithm is also analyzed. The total error introduced in …
Conductivity Of A Periodic Particle Composite With Spheroidal Inclusions, Nicola Harfield
Conductivity Of A Periodic Particle Composite With Spheroidal Inclusions, Nicola Harfield
Nicola Bowler
The effective electrical conductivity of a two-phase material consisting of a lattice of identical spheroidal inclusions in a continuous matrix is determined analytically. The inclusions are located at the node points of a simple-cubic lattice and the axis of rotation of each spheroid coincides with one of the lattice vectors, such that the spheroids are aligned with each other and with the lattice. With an electric field applied in the direction of the rotation axes of the spheroids, the electric potential is found by solving Laplace's equation. The solution is found by analytically continuing the interstitial field into the particle …
Confirmation Of Conjugation Processes During Tnt Metabolism By Axenic Plant Roots, R. Bhadra, D. G. Wayment, J. B. Hughes, Jacqueline V. Shanks
Confirmation Of Conjugation Processes During Tnt Metabolism By Axenic Plant Roots, R. Bhadra, D. G. Wayment, J. B. Hughes, Jacqueline V. Shanks
Jacqueline V. Shanks
This paper examines processes in plants for the formation of fate products of TNT beyond its aminated reduction products, 2-amino-4,6-dinitrotoluene and 4-amino-2,6- dinitrotoluene. TNT metabolites were isolated and characterized in combination with temporal analyses of product profiles and 14C distribution, in microbe-free, axenic root cultures of Catharanthus roseus. Four unique TNTderived compounds were isolated. Using evidence from 1H NMR, mass spectroscopy, HPLC, acid hydrolysis, and enzymatic hydrolysis with â-glucuronidase and â-glucosidase, they were established as conjugates formed by reactions of the amine groups of 2-amino-4,6-dinitrotoluene and 4-amino-2,6-dinitrotoluene. From the mass spectral evidence, at least a six-carbon unit from the plant …