Progress of research to identify rotating thunderstorms using satellite imagery

The possibility of detecting potentially tornadic thunderstorm cells from geosynchronous satelite imagery is determined. During the life of the contract, we examined eight tornado outbreak cases which had a total of 124 individual thunderstorm cells, 37 of which were tornadic.These 37 cells produced a total of 119 tornadoes. The outflow characteristics of all the cells were measured. Through the use of a 2-D flow field model, we were able to simulate the downstream developmemt of an anvil cloud plume which was emitted by the storm updraft at or near the tropopause. We used two parameters to characterize the anvil plume behavior: its speed of downstream propagation (U max) and the clockwise deviation of the centerline of the anvil plume from the storm relative ambient wind at the anvil plume outflow level (MDA). U max was the maximum U-component of the anvil wind parameter required to successfully maintain an envelope of translating particles at the tip of the expanding anvil cloud. MDA was the measured deviation angle acquired from McIDAS, between the storm relative ambient wind direction and the storm relative anvil plume outflow direction; tha latter being manipulated by controlling a tangential wind component to force the envelope of particles to maintain their position of surrounding the expanding outflow cloud

An investigation of the detection of tornadic thunderstorms by observing storm top features using geosynchronous satellite imagery

The number of tornado outbreak cases studied in detail was increased from the original 8. Detailed ground and aerial studies were carried out of two outbreak cases of considerable importance. It was demonstrated that multiple regression was able to predict the tornadic potential of a given thunderstorm cell by its cirrus anvil plume characteristics. It was also shown that the plume outflow intensity and the deviation of the plume alignment from storm relative winds at anvil altitude could account for the variance in tornadic potential for a given cell ranging from 0.37 to 0.82 for linear to values near 0.9 for quadratic regression. Several predictors were used in various discriminant analysis models and in censored regression models to obtain forecasts of whether a cell is tornadic and how strong tornadic it could be potentially. The experiments were performed with the synoptic scale vertical shear in the horizontal wind and with synoptic scale surface vorticity in the proximity of the cell

High temperature reactions of 1,2-dichloroethane with water vapor in a tubular reactor

This study examines the reaction of l,2-dichloroethane with water vapor. The linear-flow method is utilized, assuming plug flow without axial diffusion. Normal operation is at atmospheric pressure and the reactor is a quartz tube in a thermal region 45 cm in length. Two reactor diameters of 0.4 cm and l.05 cm are used. Water and l,2-dichloroethane enter the system in liquid phase via syringe pumps. After vaporizing in heated tubing, they are combined with argon, the reactor carrier gas. The molar ratio of water to l,2-dichloroethane is 55:l and varied residence times are achieved by changing the argon flowrate. Reactor products are identified using GC/MS. Product distributions are measured by gas chromatography. By keeping the molar ratio of water to l,2-dichloroethane very high (55:l), the rate of decomposition of 1,2-dichloroethane is of the first order. A plot of ln(C/CO) versus t results in a straight line through the origin with a slope of ka. Performing this procedure at more than one temperature allows one to graph ln ka versus (l/T). This Arrhenius plot results in a straight line with a slope of -Ea/R and y-intercept of Aa. By utilizing a relationship between the overall rate constant and rate constants for parallel reactions at the reactor wall and in the bulk stream, decoupled activation energies can be determined. The reaction was studied at three temperatures: 590°C, 630°C, and 680°C. Values of the activation energy for parallel reactions at both the wall and in the bulk stream have been calculated. They were found to be 35.4 kcal/mol and 29.0 kcal/mol, respectively. These results are in close agreement to unimolecular decomposition data in literature. Methods to correct rate constants in order to account for axial diffusion and wall reactions have been utilized. It was found that these corrections are negligible. Total decomposition of 1,2-dichloroethane occurs at temperatures greater than 800°C for a residence time range of 0.8 to l.2 sec. The principle reaction products at temperatures lower than 700°C are vinyl chloride, l-buten-3- yne, and 2-chloro-l,3-butadiene. At temperatures greater than 800°C, major reaction products include vinyl chloride, acetylene, ethene, benzene, and l,3-butadiyne. Identification of variables: Aa - apparent frequency factor, directly from experimental results (sec-1) C - concentration of unreacted l,2-dichloroethane C - initial concentration of l,2-dichloroethane entering reactor Ea - apparent activation energy, directly from experimental results (kcal/mol) ka - apparent first order rate constant, directly from experimental results (sec-l) R - gas constant, l.987 x 10-3 kcal/mol deg T - temperature (°K) t - residence time in reactor (sec

A critical evaluation of two-equation models for near wall turbulence

A variety of two-equation turbulence models,including several versions of the K-epsilon model as well as the K-omega model, are analyzed critically for near wall turbulent flows from a theoretical and computational standpoint. It is shown that the K-epsilon model has two major problems associated with it: the lack of natural boundary conditions for the dissipation rate and the appearance of higher-order correlations in the balance of terms for the dissipation rate at the wall. In so far as the former problem is concerned, either physically inconsistent boundary conditions have been used or the boundary conditions for the dissipation rate have been tied to higher-order derivatives of the turbulent kinetic energy which leads to numerical stiffness. The K-omega model can alleviate these problems since the asymptotic behavior of omega is known in more detail and since its near wall balance involves only exact viscous terms. However, the modeled form of the omega equation that is used in the literature is incomplete-an exact viscous term is missing which causes the model to behave in an asymptotically inconsistent manner. By including this viscous term and by introducing new wall damping functions with improved asymptotic behavior, a new K-tau model (where tau is identical with 1/omega is turbulent time scale) is developed. It is demonstrated that this new model is computationally robust and yields improved predictions for turbulent boundary layers

Ichthyological Bulletin of the J.L.B. Smith Institute of Ichthyology; No. 59

A historical resume of fish collecting in the Maldive Islands is presented, beginning with the collection o f J. Stanley Gardiner in 1899-1900. Specimens of Maldives fishes have been examined at the Marine Research Section of the Ministry of Fisheries and Agriculture, Republic of Maldives and the five museums which house most of the fishes that have been collected in the islands: the Natural History Museum, London; Bernice P. Bishop Museum, Honolulu; California Academy of Sciences, San Francisco; Field Museum of Natural History, Chicago; and the Senckenberg Museum, Frankfurt. A total of 899 species of epipelagic and shore fishes are recorded from the Maldives; 201 of these are new records for the islands. Thirty-two of the 899 are recorded by generic name only. Some of these could not be identified to species due to poor condition or to their being juveniles, but most appear to be undescribed.Rhodes University Libraries (Digitisation

Unusual Digital Patterns In EPS: Evidence On The Association Between Earnings Management And Company Characteristics

Prior studies (Thomas, 1989; Das and Zhang, 2003) provide evidence of earnings manipulation to achieve cognitive reference points in EPS.  The current study extends this line of research by examining the relation between unusual digital patterns in the right EPS position and specific firm characteristics.  Results suggest that the propensity to manage earnings to effect desired EPS results is particularly associated with company size and to a lesser degree with operating performance and the level of debt leverage employed

Group Invariant Solutions Without Transversality

We present a generalization of Lie\u27s method for finding the group invariant solutions to a system of partial differential equations. Our generalization relaxes the standard transversality assumption and encompasses the common situation where the reduced differential equations for the group invariant solutions involve both fewer dependent and independent variables. The theoretical basis for our method is provided by a general existence theorem for the invariant sections, both local and global, of a bundle on which a finite dimensional Lie group acts. A simple and natural extension of our characterization of invariant sections leads to an intrinsic characterization of the reduced equations for the group invariant solutions for a system of differential equations. The characterization of both the invariant sections and the reduced equations are summarized schematically by the kinematic and dynamic reduction diagrams and are illustrated by a number of examples from fluid mechanics, harmonic maps, and general relativity. This work also provides the theoretical foundations for a further detailed study of the reduced equations for group invariant solutions

Preliminary Evidence Of SFAS No. 130's Effect On Gains Trading In The Insurance Industry

Gains trading represents a form of earnings management whereby appreciated marketable securities are sold at a gain while those with a loss are retained. By not requiring unrealized gains and losses on available-for-sale securities to flow through income, SFAS No. 115 failed to close the door on this type of earnings management. With SFAS No. 130, however, these unrealized gains and losses must now be reported prominently in a financial statement as a component of comprehensive income. By examining the level of gains trading for a sample of companies in the insurance industry both before and after the implementation of SFAS No. 130, the current study provides evidence suggesting that this form of earnings management subsided subsequent to the adoption of SFAS No. 130

Unusual Digital Patterns in EPS: Evidence On the Association Between Earnings Management and Company Characteristics

Prior studies (Thomas, 1989; Das and Zhang, 2003) provide evidence of earnings manipulation to achieve cognitive reference points in EPS. The current study extends this line of research by examining the relation between unusual digital patterns in the right EPS position and specific firm characteristics. Results suggest that the propensity to manage earnings to effect desired EPS results is particularly associated with company size and to a lesser degree with operating performance and the level of debt leverage employed