Numerical analysis of spatial evolution of the small signal gain in a chemical oxygen-iodine laser operating without primary buffer gas

A chemical oxygen iodine laser (COIL) that operates without primary buffer gas has become a new way of facilitating the compact integration of laser systems. To clarify the properties of spatial gain distribution, three-dimensional (3-D) computational fluid dynamics (CFD) technology was used to study the mixing and reactive flow in a COIL nozzle with an interleaving jet configuration in the supersonic section. The results show that the molecular iodine fraction in the secondary flow has a notable effect on the spatial distribution of the small signal gain. The rich iodine condition produces some negative gain regions along the jet trajectory, while the lean iodine condition slows down the development of the gain in the streamwise direction. It is also found that the new configuration of an interleaving jet helps form a reasonable gain field under appropriate operation conditions. (c) 2007 Elsevier Ltd. All rights reserved.

The Corogal: one of the big dredges in Culebra Cut, Panama Canal (ca. 1914)

Leonard Carpenter Panama Canal Collection. Photographs: Dredging, Soldiers, and Ships. [Box 1] from the Special Collections & Area Studies Department, George A. Smathers Libraries, University of Florida.

First U.S. battleships through Panama Canal: Missouri, Ohio, Wisconsin (postcard ca 1914)

Leonard Carpenter Panama Canal Collection. Photographs: Dredging, Soldiers, and Ships. [Box 1] from the Special Collections & Area Studies Department, George A. Smathers Libraries, University of Florida.

Tow boat fleet at Paraiso, Panama Canal (ca. 1914)

Leonard Carpenter Panama Canal Collection. Photographs: Dredging, Soldiers, and Ships. [Box 1] from the Special Collections & Area Studies Department, George A. Smathers Libraries, University of Florida.

View of Paraiso Yard showing dredging equipment, Panama Canal. (ca. 1914)

Leonard Carpenter Panama Canal Collection. Photographs: Dredging, Soldiers, and Ships. [Box 1] from the Special Collections & Area Studies Department, George A. Smathers Libraries, University of Florida.

Emergency dam at Pedro Miguel, Panama Canal (ca. 1914)

Leonard Carpenter Panama Canal Collection. Photographs: Dredging, Soldiers, and Ships. [Box 1] from the Special Collections & Area Studies Department, George A. Smathers Libraries, University of Florida.

Lantern spillway and hydroelectric plant, Panama Canal (ca. 1914)

Leonard Carpenter Panama Canal Collection. Photographs: Dredging, Soldiers, and Ships. [Box 1] from the Special Collections & Area Studies Department, George A. Smathers Libraries, University of Florida.

U.S.S. Ohio, Panama Canal (ca. 1914)

Leonard Carpenter Panama Canal Collection. Photographs: Dredging, Soldiers, and Ships. [Box 1] from the Special Collections & Area Studies Department, George A. Smathers Libraries, University of Florida.

The hydrography of Elkhorn Slough: a shallow California coastal Eebayment: Annual Report, Part 2, 1973

From October 1970 through February 1972, temperature, salinity, dissolved oxygen, secchi depth and five major nutrients were observed at approximately monthly intervals in Elkhorn Slough and Moss Landing Harbor. In addition, similar hourly observations were made during two tidal studies during the wet and dry seasons. From the salinity measurements during the summer, a salt balance for Elkhorn Slough is formulated and rnean eddy diffusion coefficients are determined. The diffusion nlodel applied to longitudinal phosphate distributions yielded a mean diffusive flux of 12 kg P04/day (140 pg-at/m^2/day) for the area above the mean tidal prism. Consistent differences, apparently due to differing regenerati on ra tes, were observed in the phosphate and nitrogen distributions. Bottom sediments are proposed as a possible source for phosphate and as a sink for fixed nitrogen. Dairy farms located along central Elkhorn Slough are apparently a source for reduced nitrogen. During summer, nitrogen was found to be the limiting nutrient for primary production in the upper slough. Tidal observations indicated fresh water of high nutrient concentration consistently entered the harbor from fresh water sources to the south. This source water had a probable phosphate concentration of 40 to 60 ug-at/l and seasonally varying P:N ratio of 1:16 and 1:5 during the winter and summer respectively. Net production and respiration rates are calculated from diurnal variations in dissolved oxygen levels observed in upper Elkhorn Slough. Changes in phosphate associated with the variations in oxygen was close to the accepted ratio of 1:276 by atoms. Document is 88 pages.

Effect of Cattail (Typha domingensis) Extracts, Leachates, and Selected Phenolic Compounds on Rates of Oxygen Production by Salvinia (Salvinia minima)

Salvinia (Salvinia minima Willd.) is a water fern found in Florida waters, usually associated with Lemna and other small free-floating species. Due to its buoyancy and mat-forming abilities, it is spread by moving waters. In 1994, salvinia was reported to be present in 247 water bodies in the state (out of 451 surveyed public waters, Schardt 1997). It is a small, rapidly growing species that can become a nuisance due to its explosive growth rates and its ability to shade underwater life (Oliver 1993). Any efforts toward management of salvinia populations must consider that, in reasonable amounts, its presence is desirable since it plays an important role in the overall ecosystem balance. New management alternatives need to be explored besides the conventional herbicide treatments; for example, it has been shown that the growth of S. molesta can be inhibited by extracts of the tropical weed parthenium (Parthenium hysterophorus) and its purified toxin parthenin (Pande 1994, 1996). We believe that cattail, Typha spp. may be a candidate for control of S. minima infestations. Cattail is an aggressive aquatic plant, and has the ability to expand over areas that weren't previously occupied by other species (Gallardo et al. 1998a and references cited there). In South Florida, T. domingensis is a natural component of the Everglades ecosystem, but in many cases it has become the dominant marsh species, outcompeting other native plants. In Florida public waters, this cattail species is the most dominant emergent species of aquatic plants (Schardt 1997). Several factors enable it to accomplish opportunistic expansion, including size, growth habits, adaptability to changes in the surroundings, and the release of compounds that can prevent the growth and development of other species. We have been concerned in the past with the inhibitory effects of the T. domingensis extracts, and the phenolic compounds mentioned before, towards the growth and propagation of S. minima (Gallardo et al. 1998b). This investigation deals with the impact of cattail materials on the rates of oxygen production of salvinia, as determined through a series of Warburg experiments (Martin et al. 1987, Prindle and Martin 1996).

Bottle and Pumpcast Data from the 1988 Black Sea Expedition

This report contains inorganic nutrient chemistry, sulfide and oxygen data collected during cruises 2 through 5 of the 1988 Black Sea Oceanographic Expedition aboard the R/V Knorr. Continuous nutrient and sulfide data were obtained in the upper 375 m using a pumped profiling system. Discrete samples were collected from rosette-CTD casts. The corresponding physical oceanographic data have been presented by White et al. (1989). Although all of the data reported has been edited at least twice, errors may remain. We encourage queries and plan to distribute updates on electronic media if there are any non-trivial changes.

An Easy-to-Construct Automated Winkler Titration System

The instrument described in this report is an updated version of the high precision, automated Winkler titration system described by Friederich et al.(1984). The original instrument was based on the work of Bryan et al. (1976) who developed a colorimetric endpoint detector and on the work of Williams and Jenkinson (1982) who produced an automated system that used this detector. The goals of our updated version of the device described by Friederich et al. (1984) were as follows: 1) Move control of the system to the MS-DOS environment because HP-85 computers are no longer in production and because more user-friendly programs could be written using the IBM XT or AT computers that control the new device. 2) Use more "off the shelf" components and reduce the parts count in the new system so that it could be easily constructed and maintained. This report describes how to construct and use the new automated Winkler titration device. It also includes information on the chemistry of the Winkler titration, and detailed instructions on how to prepare reagents, collect samples, standardize and perform the titrations (Appendix I: Codispoti, L.A. 1991 On the determination of dissolved oxygen in sea water, 15pp.). A disk containing the program needed to operate the new device is also included. (pdf contains 33 pages)

Modified Simplified Rate Equation Model of Flowing Chemical Oxygen-Iodine Laser and its Application

A modified simplified rate equation (RE) model of flowing chemical oxygen-iodine laser (COIL), which is adapted to both the condition of homogeneous broadening and inhomogeneous broadening being of importance and the condition of inhomogeneous broadening being predominant, is presented for performance analyses of a COIL. By using the Voigt profile function and the gain-equal-loss approximation, a gain expression has been deduced from the rate equations of upper and lower level laser species. This gain expression is adapted to the conditions of very low gas pressure up to quite high pressure and can deal with the condition of lasing frequency being not equal to the central one of spectral profile. The expressions of output power and extraction efficiency in a flowing COIL can be obtained by solving the coupling equations of the deduced gain expression and the energy equation which expresses the complete transformation of the energy stored in singlet delta state oxygen into laser energy. By using these expressions, the RotoCOIL experiment is simulated, and obtained results agree well with experiment data. Effects of various adjustable parameters on the performances of COIL are also presented.