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Cleveland State University

2003

Articles 1 - 13 of 13

Full-Text Articles in Physics

Twin-Rainbow Metrology. I. Measurement Of The Thickness Of A Thin Liquid Film Draining Under Gravity, Charles L. Adler, James A. Lock, Ian P. Rafferty, Wayne Hickok Nov 2003

Twin-Rainbow Metrology. I. Measurement Of The Thickness Of A Thin Liquid Film Draining Under Gravity, Charles L. Adler, James A. Lock, Ian P. Rafferty, Wayne Hickok

Physics Faculty Publications

We describe twin-rainbow metrology, a new optical technique used to measure the thickness of thin films in a cylindrical geometry. We also present an application of the technique: measurement of the thickness of a Newtonian fluid draining under gravity. We compare these measurements with fluid mechanics models. (C) 2003 Optical Society of America.

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Mode Structure Of Diffusive Transport In Hydroxypropylcellulose:Water, George D.J. Phillies, Robert O. Connell, Paul Whitford, Kiril A. Streletzky Nov 2003

Mode Structure Of Diffusive Transport In Hydroxypropylcellulose:Water, George D.J. Phillies, Robert O. Connell, Paul Whitford, Kiril A. Streletzky

Physics Faculty Publications

A systematic analysis of the mode structure of diffusive relaxations in 1 MDa hydroxypropylcellulose(HPC):water is presented. New methods and data include (1) use of integral spectral moments to characterize nonexponential decays, (2) spectra of small probes in concentrated HPC solutions, (3) temperature dependence of the mode structure, and (4) comparison of optical probe spectra and spectra of probe-free polymer solutions. We find that (1) probe and polymer relaxations are in general not the same; (2) the apparent viscometric crossover near ct≈6 g/l is echoed by probe behavior; (3) our HPC solutions have a characteristic dynamic length, namely the 50 nm …

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Entropic Characterization Of Distributive Mixing In Polymer Processing Equipment, Winston Wang, Ica Manas Zloczower, Miron Kaufman Jul 2003

Entropic Characterization Of Distributive Mixing In Polymer Processing Equipment, Winston Wang, Ica Manas Zloczower, Miron Kaufman

Physics Faculty Publications

Mixing is an integral component of most polymer processing operations as material properties are highly influenced by the quality of mixing. The degree of distributive mixing (system homogeneity) is assessed by calculating the evolution of Renyi relative entropies for the minor component along a continuous processing equipment. The Renyi entropy involves a β parameter, which represents weighting given to the concentration of the minor component in small, localized regions. Different aspects of mixing can thus be analyzed, from the amount of void spaces to the concentration of the region where mixing is the worst in terms of the minor component. …

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Use Of Optical Tweezers For Colloid Science, Andrew Resnick Jun 2003

Use Of Optical Tweezers For Colloid Science, Andrew Resnick

Physics Faculty Publications

A space-borne optical tweezer apparatus for use with colloidal crystallization experiments has been characterized. The trapping force has been measured as a function of index mismatch between colloidal microspheres and the surrounding fluid and as a function of particle size. This work also presents a method to determine the refractive index of a colloidal microsphere, which is then used to calculate the applied trapping force for the case of an arbitrary background fluid. This is useful for work with dense colloidal suspensions when the usual (e.g., Stokes flow) trap force measurement methods do not apply, as well as microrheological studies …

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Small Angle Neutron Scattering From D2o–H2o Nanodroplets And Binary Nucleation Rates In A Supersonic Nozzle, Christopher H. Heath, Kiril A. Streletzky, Barbara E. Wyslouzil, Judith Woelk, Reinhard Strey Mar 2003

Small Angle Neutron Scattering From D2o–H2o Nanodroplets And Binary Nucleation Rates In A Supersonic Nozzle, Christopher H. Heath, Kiril A. Streletzky, Barbara E. Wyslouzil, Judith Woelk, Reinhard Strey

Physics Faculty Publications

Small angle neutron scattering (SANS) experiments were used to characterize binary nanodroplets composed of D2O and H2O. The droplets were formed by expanding dilute mixtures of condensible vapor in a N2 carrier gas through a supersonic nozzle, while maintaining the onset of condensation at a fixed position in the nozzle. It is remarkable, given the small coherent scattering length density of light water, that even the pure H2O aerosol gave a scattering signal above background. The scattering spectra were analyzed assuming a log-normal distribution of droplets. On average, the geometric radius of the nanodroplets rg was rg=13 (±1) nm, the …

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Role Of The Tunneling Ray In Near-Critical-Angle Scattering By A Dielectric Sphere, James A. Lock Mar 2003

Role Of The Tunneling Ray In Near-Critical-Angle Scattering By A Dielectric Sphere, James A. Lock

Physics Faculty Publications

The scattering far zone for light transmitted through a sphere following p - 1 internal reflections by a family of near-grazing incident rays is subdivided into a lit region and a shadow region. The sharpness of the ray theory transition between the lit and the shadow regions is smoothed in wave theory by radiation shed by electromagnetic surface waves. It is shown that when higher-order terms in the physical optics approximation to the phase of the partial-wave scattering amplitudes are included, the transition between the lit and the shadow regions becomes a two-ray-to-zero-ray transition, called a superweak caustic in analogy …

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Detection Sensitivity Optimization Of Optical Signals Generated By Fiber Optic Bragg Gratings Under Dynamic Excitation, John Lekki, James A. Lock Feb 2003

Detection Sensitivity Optimization Of Optical Signals Generated By Fiber Optic Bragg Gratings Under Dynamic Excitation, John Lekki, James A. Lock

Physics Faculty Publications

The dynamic response of a fiber optic Bragg grating to mechanical vibrations is examined both theoretically and experimentally. The theoretical expressions describing the consequences of changes in the grating's reflection spectrum are derived for partially coherent beams in an interferometer. The analysis is given in terms of the dominant wavelength, optical bandwidth, and optical path difference of the interfering signals. Changes in the reflection spectrum caused by a periodic stretching and compression of the grating are experimentally measured using an unbalanced Michelson interferometer, a Michelson interferometer with a nonzero optical path difference. The interferometer's sensitivity to changes in the dominant …

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Analysis Of The Shadow-Sausage Effect Caustic, James A. Lock, Charles L. Adler, Diana Ekelman, Jonathan Mulholland, Brian Keating Jan 2003

Analysis Of The Shadow-Sausage Effect Caustic, James A. Lock, Charles L. Adler, Diana Ekelman, Jonathan Mulholland, Brian Keating

Physics Faculty Publications

We analyze the optical caustic produced by light refracted at the curved meniscus surrounding a cylindrical rod standing partially out of a liquid-filled container. When the rod is tilted from the vertical or when light is diagonally incident, the caustic is a four-cusped astroid with two of its cusps obscured by the rod's shadow. If a portion of the flat end of the rod is raised above the water level, the caustic evolves into a pattern of five interlocking cusps. The five cusps result from symmetry breaking of a three-cusped surface perturbation caustic. (C) 2003 Optical Society of America.

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Experimental Observation Of Total-Internal-Reflection Rainbows, Charles L. Adler, James A. Lock, Jonathon Mulholland, Brian Keating, Diana Ekelman Jan 2003

Experimental Observation Of Total-Internal-Reflection Rainbows, Charles L. Adler, James A. Lock, Jonathon Mulholland, Brian Keating, Diana Ekelman

Physics Faculty Publications

A new class of rainbows is created when a droplet is illuminated from the inside by a point light source. The position of the rainbow depends on both the index of refraction of the droplet and the position of the light source, and the rainbow vanishes when the point source is too close to the center of the droplet. Here we experimentally measure the position of the transmission and one-internal-reflection total-internal-reflection rainbows, and the standard (primary) rainbow, as a function of light-source position. (C) 2003 Optical Society of America.

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Simulating Coronas In Color, Stanley D. Gedzelman, James A. Lock Jan 2003

Simulating Coronas In Color, Stanley D. Gedzelman, James A. Lock

Physics Faculty Publications

Coronas are simulated in color by use of the Mie scattering theory of light by small droplets through clouds of finite optical thickness embedded in a Rayleigh scattering atmosphere. The primary factors that affect color, visibility, and number of rings of coronas are droplet size, width of the size distribution, and cloud optical thickness. The color sequence of coronas and iridescence varies when the droplet radius is smaller than similar to6-mum. As radius increases to approximately 3.5 mum, new color bands appear at the center of the corona and fade as they move outward. As the radius continues to increase …

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Light And Color In The Open Air: Introduction To The Feature Issue, Charles L. Adler, James A. Lock Jan 2003

Light And Color In The Open Air: Introduction To The Feature Issue, Charles L. Adler, James A. Lock

Physics Faculty Publications

This special feature of Applied Optics reports the results of new experimental and theoretical research concerning a number of naked-eye optical phenomena, including ice-crystal halo displays, mirages, rainbows, glories, optical caustics, clear-sky phenomena, cloud coronas, cloud iridescence, and the extinction of skylight. (C) 2003 Optical Society of America.

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Modeling Of Hysteresis And Magnetization Curves For Hexagonally Ordered Electrodeposited Nanowires, Petru S. Fodor, Georgy M. Tsoi, Lowell E. Wenger Jan 2003

Modeling Of Hysteresis And Magnetization Curves For Hexagonally Ordered Electrodeposited Nanowires, Petru S. Fodor, Georgy M. Tsoi, Lowell E. Wenger

Physics Faculty Publications

A computational model has been developed to investigate how the magnetostatic interactions affect the hysteresis and magnetization curves for hexagonal arrays of magnetic nanowires. The magnetization coupling between nanowires arises from the stray fields produced by the other nanowires composing the array such that the field at each nanowire is the sum of the external field and the interaction field with the other nanowires. Using only two adjustable parameters: the interaction between nearest neighbors and the width of the Gaussian distribution in switching fields centered around the measuredcoercivity, simulations are compared with the experimentally measuredhysteresis and magnetization curves for electrodepositedCo0.45 …

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Zero Magnetization States In Electrodeposited Co0.45fe0.55 Nanowire Arrays, Petru S. Fodor, Georgy M. Tsoi, Lowell E. Wenger Jan 2003

Zero Magnetization States In Electrodeposited Co0.45fe0.55 Nanowire Arrays, Petru S. Fodor, Georgy M. Tsoi, Lowell E. Wenger

Physics Faculty Publications

Co0.45Fe0.55 alloy nanowires with 12 to 35 nm diameter and 12 μm length were fabricated by electrodeposition in porous anodic alumina templates. The initial magnetization curves reveal that the zero magnetization state is not unique and is determined by the field history (acdemagnetization process) leading to the zero average moment state. For acdemagnetization processes with the field applied parallel to the nanowire axis, the subsequent magnetization curves suggest that an individual nanowire behaves as a single domain with neighboring nanowires being antiparallel to each other in the zero magnetization state. However, for a demagnetization process with the field applied perpendicular …

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