Office of the Provost and Vice President of Academic Affairs Scholarship Copyright (c) 2013 California Polytechnic State University All rights reserved. http://digitalcommons.calpoly.edu/provost_schol Recent documents in Office of the Provost and Vice President of Academic Affairs Scholarship en-us Wed, 01 May 2013 13:11:26 PDT 3600 The Photolysis of Propane at 123.6 nm http://digitalcommons.calpoly.edu/provost_schol/65 http://digitalcommons.calpoly.edu/provost_schol/65 Thu, 08 Jan 2009 16:50:24 PST Propane has been photolyzed at 123.6 nm, in the presence and absence of O2, at pressures from 2–380 Torr. All products except ethane exhibit a pressure dependence which is attributed to secondary dissociation of the primary fragments, H2, CH4, C2H4, and C3H6. It is assumed that the range of energies carried by these fragments is broad enough that some will not dissociate even at low pressures while others of the same species cannot be stabilized even at high pressures. An internally consistent analysis rationalizes the entire observed product spectrum, with some uncertainty arising from an ambiguity in the source of acetylene. The following primary quantum yields, prior to secondary dissociation, are estimated:
C3H8 + hv = H2 + C3H6 φ = 0.42 mol/einstein
= C2H4 + CH4 φ = 0.47 mol/einstein
= CH2 + C2H6 φ = 0.09 mol/einstein

]]> James H. Vorachek et al. Radiolysis of Liquid Propane: Radical Reactions http://digitalcommons.calpoly.edu/provost_schol/64 http://digitalcommons.calpoly.edu/provost_schol/64 Thu, 08 Jan 2009 16:13:42 PST The radical reactions in the liquid phase γ-radiolysis of propane have been studied from –130 to 35°C and compared with the gas-phase radiolysis at 35°C. Oxygen was used as a scavenger to separate thermal radical yields, and effects of phase and temperature on the radical yields were assessed. The gas-liquid phase change(a) decreases total decomposition by about 14%,(b) increases disproportionation/combination (D/C) ratios for all radicals by 30% and (c) decreases the isopropyl/n-propyl radical ratio. The decrease in liquid temperature (a) changes the predominant reaction of H atoms from abstraction from propane to addition to product propylene below –78°C at doses of 1 Mrad, (b) increases the D/C ratios by 31% and (c) decreases the isopropyl/n-propyl radical ratio. Dose effects were briefly studied; they are complex and cannot be explained by radical reactions alone.

]]> Robert D. Koob et al. Radiolysis of Liquid Propane: non-Radical Reactions http://digitalcommons.calpoly.edu/provost_schol/63 http://digitalcommons.calpoly.edu/provost_schol/63 Thu, 08 Jan 2009 16:10:38 PST The yields of ionic and excited molecule reactions in -radiolysis of liquid propane from 35 to –130°C have been assessed by isotopic analysis of C3H8+ C3D8+ O2 and CH3CD2CH3+ O2mixtures. From a comparison with gas phase data the following conclusions are reached for the gas to liquid phase change : (a) the ionic decomposition yield decreases by ≤ 69%, (b) the net excited molecule decomposition yield decreases by 7% or less, (c) parent ion fragmentation still occurs in the liquid and exhibits fragmentation processes requiring from 1-4 eV excitation, (d) the H–2/H– transfer reaction ratio for C2H+4+ C3H8 seems to be increased, and (e) the isotopic decomposition of CH3CD2CH3 is drastically changed.

]]> Robert D. Koob et al. Hydrogeochemical Aspects of Surface Mine Reclamation in the Northern Great Plains http://digitalcommons.calpoly.edu/provost_schol/62 http://digitalcommons.calpoly.edu/provost_schol/62 Thu, 08 Jan 2009 16:10:36 PST Studies of several coal-mining sites in western North Dakota have resulted in the development of a hydrogeochemical model which accounts for the observed chemical characteristics of subsurface water in undisturbed settings. Critical hydrogeochemical processes include sulfide oxidation, gypsum precipitation and dissolution, carbonate mineral dissolution and cation exchange.

In the semi-arid climate of western North Dakota, the near-surface several meters of the landscape is constantly subjected to alternate wetting/drying. This mechanism is the key to hydrogeochemical evolution of both pore water in the rooting zone and subsurface water that eventually reaches the water table.

Recent refinements in the hydrogeochemical model have focused on the sulfur cycle and determination of the applicability of the model to postmining (spoils) landscapes. Field activities have included detailed groundwater instrumentation of undisturbed and spoils areas at two geologically distinctive mine sites in western North Dakota. Refinement of the model included analyses of the texture, bulk mineralogy, clay mineralogy, sulfide abundance, and sulfur concentration in overburden core samples. Laboratory experiments were designed to determine the source and mechanisms of sulfate salt production from overburden samples.

From the study we conclude that the hydrogeochemical model is equally applicable to undisturbed and spoils landscapes and that the major species of concern in this region are sodium and sulfate. This research indicates that the major source of sulfate is sulfides in the overburden and that the solubility of sulfate in groundwater in these settings is largely controlled by the sodium/calcium ratio.

We also conclude that negative hydrogeochemical impacts resulting from surface mining in the Northern Great Plains will include increased mineralization of groundwater and sodic and salt effects on plants. The degree of these impacts will be dependent upon site· specific hydrogeological, geochemical, and mineralogical variables. A consideration of these non-soils aspects of surface-mined lands thus is essential to proper surface-mine reclamation design in this region.

]]> Gerald H. Groenewold et al. Excited States and Photochemistry of Saturated Molecules http://digitalcommons.calpoly.edu/provost_schol/61 http://digitalcommons.calpoly.edu/provost_schol/61 Thu, 08 Jan 2009 15:54:31 PST The molecular structures and bond energies in the low-lying excited states of n-alkanes from methane to n-pentane are investigated using the semi-empirical INDO method with configuration interaction. In general the calculated geometries and bond energies are consistent with the known threshold photochemistry of these molecules, the only exception being the prediction of vicinal (rather than geminal) elimination of H2 in ethane. It appears that INDO overestimates the amount of angular distortion in these excited states.

]]> Patrick M. Saatzer et al. Ultrasonic Technique for Investigation of the Effect of Grid-Generated Turbulence on Sound Wave Propagation http://digitalcommons.calpoly.edu/provost_schol/60 http://digitalcommons.calpoly.edu/provost_schol/60 Thu, 18 Dec 2008 13:41:42 PST This paper concerns an experimental study of the effects of the grid-generated turbulence on the propagation of acoustical waves in a wind tunnel. Turbulence effects are investigated using ultrasound time-of-flight method, employing counter-propagating ultrasonic pulses. Turbulence effects are an important source of error in the active probing of the atmosphere using sound sources. The emphasis is on the propagation time fluctuations and their interpretation using theoretical analysis of Kolmogorov.

]]> Tatiana A. Andreeva et al. The WPI Space Glove Design Project http://digitalcommons.calpoly.edu/provost_schol/59 http://digitalcommons.calpoly.edu/provost_schol/59 Wed, 22 Oct 2008 12:24:17 PDT WPI was one of four colleges and universities awarded NASA grants for student design and development of an improved glove for space suits. This paper traces the design, development and testing of the WPI prototype glove. Test results showed that the glove did not significantly limit hand and finger motion when pressurized at 8 psi, except in the spherical grip mode. This project demonstrated that problems originating from space technology provide excellent vehicles for student learning and can generate creative solutions.

]]> William W. Durgin et al. The Use of Ultrasound Imaging in the In-Vivo Determination of Normal Human Arterial Compliance http://digitalcommons.calpoly.edu/provost_schol/58 http://digitalcommons.calpoly.edu/provost_schol/58 Wed, 22 Oct 2008 12:24:15 PDT Elastic properties of major arteries were measured in vivo in ten normal volunteers, age 26 to 44 years (mean = 32 years). A B-mode ultrasound imager was used to noninvasively measure mean diameter and pulsatile diameter change at five locations along the main arteries in the abdomen and the lower extremities. Together with pulsatile pressure (measured by the auscultatory method), strain (ε), compliance (C) and the pressure-strain elastic modulus (Ep l/C) were calculated. Ep increased significantly along the arterial tree; mean values (x105 N/m-2 ) were: 0.99 aorta, 1.21 common iliac artery (CIA), 1.43 common femoral artery (CFA), 1.57 superficial femoral artery (SFA), and 1.56 popliteal (POP) artery.

]]> Lauren I. Stratouly et al. Ultrasonic Method for Aircraft Wake Vortex Detection http://digitalcommons.calpoly.edu/provost_schol/57 http://digitalcommons.calpoly.edu/provost_schol/57 Wed, 22 Oct 2008 12:24:13 PDT This paper describes the experimental proof of concept study for an ultrasonic method of wake vortex detection. This new acoustic method uses travel time of acoustic pulses around a closed path to measure the net circulation within the acoustic path. In this application the closed path encloses the vorticity shed from one side of a Piper PA-28 aircraft wing. Magnitude and sign of circulation detected is comparable to the expected circulation generated by the Piper PA-28 test aircraft. This study demonstrates the validity of the acoustic method in detecting aircraft wake vortices. Further investigations and applications using this technique are discussed.

]]> Rebecca J. Rodenhiser et al. Ultrasonic Measurement of the Geometric Parameters of Gaseous Voids in Low Gravity Fluid Containers http://digitalcommons.calpoly.edu/provost_schol/56 http://digitalcommons.calpoly.edu/provost_schol/56 Wed, 22 Oct 2008 12:24:10 PDT A demonstration system for the ultrasonic gauging of fluids in low-gravity has been designed and tested. For purposes of simplification, it was assumed that vapor within a liquid container in low-gravity would form a spherical bubble which would float freely in the container. The project was designed to show that ultrasonic techniques could be used to determine the geometry of the resulting sphere given a worst-case transducer arrangement. The motivation was to simplify transducer mounting requirements so that propellant or other storage vessels could be fitted with ultrasonic gauging systems with a single or perhaps a few transducer penetrations. Data was collected from a planar array of transducers. The high error expected due to the low triangulation was reduced by maximizing the amount of data collected. This was accomplished using the transducers in both pulse/echo and pitch/catch operational modes.

]]> A. T. Patten et al. Tone Generation by Flow Past Deep Wall Cavities http://digitalcommons.calpoly.edu/provost_schol/55 http://digitalcommons.calpoly.edu/provost_schol/55 Wed, 22 Oct 2008 12:24:08 PDT Flow past deep wall cavities exhibits strong interaction with the standing wave system in the cavity. The shear layer separating the exterior flow from the cavity flow supports instabilities which excite the normal cavity modes. In turn, the cavity wave system reinforces the instabilities. Experimental studies have shown that two distinct instability modes are encountered as the external velocity is increased. The pressure coefficient versus Strouha1 number behavior reveals two maxima which correspond to different instability modes of the shear layer. Flow visualization studies have shown that these modes correspond to distinct shear 1ayer vortex structures. At high velocities, single large-scale vortices are formed on the interface. At lower velocities, two vortices are present, simultaneously.

]]> D. D. Erickson et al. Teaching the Necessary "Soft Skills" Through Corporate-Based Projects http://digitalcommons.calpoly.edu/provost_schol/54 http://digitalcommons.calpoly.edu/provost_schol/54 Wed, 22 Oct 2008 12:24:06 PDT Lance Schachterle et al. Noninvasive Detection of Arterial Occlusive Disease: a Theoretical and Model Study http://digitalcommons.calpoly.edu/provost_schol/53 http://digitalcommons.calpoly.edu/provost_schol/53 Wed, 22 Oct 2008 12:24:03 PDT To develop a noninvasive method of detecting arterial occlusive disease, pulse waveforms were recorded at two locations on the lower extremities of young normal volunteers and patients with arteriographically confirmed arterial occlusive disease. Pulses were monitored using impedance plethysmography at the knee· and the iliac regions. The frequency spectra of the abnormal iliac waveforms contained 4-5 harmonics as compared to the 2-3 harmonics present in normals'. It was hypothesized that the occurrence of high frequencies resulted from pulse wave interactions with diseased portions of the vessel. This paper will present the results of a theoretical and experimental model developed to test this hypothesis.

]]> Lauren I. Stratouly et al. Effect of Chaos and Stochastics Induced By Internal Waves on Acoustic Wave Propagation http://digitalcommons.calpoly.edu/provost_schol/52 http://digitalcommons.calpoly.edu/provost_schol/52 Wed, 22 Oct 2008 12:24:01 PDT In the present paper the eikonal equation is considered in the form of a second order, nonlinear ordinary differential equation with harmonic excitation due to internal wave. The harmonic excitation is taken imperfect, i.e. there is a random phase modulation due to Gaussian white noise. The amplitude and wavelength of the acoustic wave are used as the principle signal characteristics in bifurcation analysis. The regions of instability, identified using the bifurcation diagrams, examined through phase diagrams and Poincare maps. The effect of stochastic nature in addition to chaotic one of internal waves is demonstrated by means of comparison of the numerical data obtained for perfectly periodic excitation. Preliminary analysis shows very strong dependence on noise intensity at some values of amplitude and wave length of internal wave.

]]> Tatiana A. Andreeva et al. Modeling of Purge Valve Closure http://digitalcommons.calpoly.edu/provost_schol/51 http://digitalcommons.calpoly.edu/provost_schol/51 Fri, 17 Oct 2008 16:24:09 PDT In some nuclear reactor containment isolation applications, butterfly valves with pneumatic actuators are used to close pipelines in the event of containment pressure transients resulting from postulated accidents. A model is developed which predicts the closure time history of such valve/actuator systems under prescribed transients. Examples are presented which show the importance of the valve and actuator characteristics. It was found that actuation delays of sufficient magnitude could allow the dynamic torque to exceed the available actuator torque, thus preventing valve closure.

]]> William W. Durgin et al. Circulation Measurements About a Rapidly Pitching Airfoil Using an Ultrasonic System http://digitalcommons.calpoly.edu/provost_schol/50 http://digitalcommons.calpoly.edu/provost_schol/50 Fri, 17 Oct 2008 16:24:07 PDT An ultrasonic system was developed to measure the circulation about a sinusoidally pitching NACA 4418 airfoil. The system consisted of two opposing ultrasonic ranging modules arranged such that the differences between the sound propagation times in opposite directions could be related to the instantaneous circulation. For the stationary airfoil, the measured lift coefficient was within 5% of the tabulated data while the observed stall angle was 2° less than the tabulated value. Measured hysteresis loops verified the applicability of the ultrasonic system to the dynamic stall problem. Measured maximum lift coefficients increased linearly with reduced frequency up to a value of 0.05. Beyond this value, a slower increase of maximum CL with reduced frequency was observed. Nomenclature coefficients are primarily dependent on the angle of observed.

]]> F. J. Weber, Jr. et al. LDV Measurements of the Unsteady Shear Layer Above a Resonant Cavity http://digitalcommons.calpoly.edu/provost_schol/49 http://digitalcommons.calpoly.edu/provost_schol/49 Fri, 17 Oct 2008 16:24:04 PDT Flow past a wall mounted cavity can excite strong acoustic resonance in the cavity. The acoustic field in the cavity is coupled to the unstable shear layer at the mouth of the cavity. Flow visualization revealed that the flow in the shear layer is characterized by periodic formation of large-scale vortices and convection of these vortices downstream to the trailing edge. A LDV system was utilized to measure the periodic changes in the shear layer flow. A two step data analysis process was used to reconstruct the velocity field. The process consisted of phase conditioned averaging and a Fourier series approximation.

]]> H. R. Graf et al. The Direct Measurement of Circulation in Free Surface Vortices http://digitalcommons.calpoly.edu/provost_schol/48 http://digitalcommons.calpoly.edu/provost_schol/48 Fri, 17 Oct 2008 16:24:02 PDT Ultrasonic techniques have been used to directly and non-intrusively measure the circulation of free surface vortices. All experiments were performed in a vertical cylindrical tank with a central drain and a tangential inlet The circulation was measured on a closed triangular path by measuring the difference in upstream and downstream transit-times. Circulation was measured as a function of the Reynolds and Froude numbers and was found to increase as the Reynolds and Froude numbers increased. The circulation was also found to be proportional to the square of the ratio of the drain diameter to cylinder diameter while the ratio of fluid depth to cylinder diameter was held constant. Minimum surface elevations were measured at various conditions and attempts were made to correlate them with measured circulation.

]]> R. H. Smith et al. Analysis of Natural Convection in a Low Gravity Environment http://digitalcommons.calpoly.edu/provost_schol/47 http://digitalcommons.calpoly.edu/provost_schol/47 Fri, 17 Oct 2008 16:24:00 PDT Natural convection inside a spherical container was studied experimentally with two apparatuses at low buoyancy levels. The data generated by these experiments, plotted nondimensionally as the Nusselt versus Rayleigh numbers, gives correlations for Rayleigh numbers between 103 and 108, a range which was previously untested. These results show that natural convection has significant effects at a Rayleigh number of 10>sup>3 and higher, although the behavior of the Nusselt number as the conduction limit is approached is still unknown for a spherical geometry.

]]> Ethan Mattor et al. A Comparison of Low-Gravity Measurements On-Board Columbia During STS-40 http://digitalcommons.calpoly.edu/provost_schol/46 http://digitalcommons.calpoly.edu/provost_schol/46 Mon, 29 Sep 2008 09:43:00 PDT The first NASA Spacelab Life Sciences mission (SLS-1) flew 5 June to 14 June 1991 on the orbiter Columbia (STS-40). The purpose of the mission was to investigate the human body's adaptation to the low-gravity conditions of space flight and the body's readjustment after the mission to the 1 g environment of earth. In addition to the life sciences experiments manifested for the Spacelab module, a variety of experiments in other scientific disciplines flew in the Spacelab and in Get Away Special (GAS) Canisters on the GAS Bridge Assembly. Several principal investigators designed and flew specialized accelerometer systems to better assess the results of their experiments by means of a low-gravity environment characterization. This was also the first flight of the NASA Microgravity Science and Applications Division (MSAD) sponsored Space Acceleration Measurement System (SAMS) and the first flight of the NASA Orbiter Experiments Office (OEX) sponsored Orbital Acceleration Research Experiment accelerometer (OARE). We present a brief introduction to seven STS-40 accelerometer systems and discuss and compare the resulting data. During crew sleep periods, acceleration magnitudes in the 10-6 to 10-5 g range were recorded in the Spacelab module and on the GAS Bridge Assembly. Magnitudes increased to the 10-4 g level during periods of nominal crew activity. Vernier thruster firings caused acceleration shifts on the order of 10-4 g and primary thruster firings caused accelerations as great as 10-2 g. Frequency domain analysis revealed typical excitation of Orbiter and Spacelab structural modes at 3.5, 4.7, 5.2, 6.2, 7, and 17 Hz.

]]> M. J.B. Rogers et al.