Magnetically switched power supply system for lasers

A laser power supply system is described in which separate pulses are utilized to avalanche ionize the gas within the laser and then produce a sustained discharge to cause the gas to emit light energy. A pulsed voltage source is used to charge a storage device such as a distributed capacitance. A transmission line or other suitable electrical conductor connects the storage device to the laser. A saturable inductor switch is coupled in the transmission line for containing the energy within the storage device until the voltage level across the storage device reaches a predetermined level, which level is less than that required to avalanche ionize the gas. An avalanche ionization pulse generating circuit is coupled to the laser for generating a high voltage pulse of sufficient amplitude to avalanche ionize the laser gas. Once the laser gas is avalanche ionized, the energy within the storage device is discharged through the saturable inductor switch into the laser to provide the sustained discharge. The avalanche ionization generating circuit may include a separate voltage source which is connected across the laser or may be in the form of a voltage multiplier circuit connected between the storage device and the laser

Models suggesting field experiments to test two hypotheses explaining successional diversity

A simple mathematical model of competition is developed that includes two alternative mechanisms promoting successional diversity. The first underpins the competition-colonization hypothesis in which early successional species are able to persist because they colonize disturbed habitats before the arrival of late successional dominant competitors. The second underpins the niche hypothesis, in which early successional species are able to persist, even with unlimited colonization by late successional dominants, because they specialize on the resource-rich conditions typical of recently disturbed sites. We modify the widely studied competition-colonization model so that it also includes the mechanism behind the niche hypothesis. Analysis of this model suggests simple experiments that determine whether the successional diversity of a field system is maintained primarily by the competition-colonization mechanism, primarily by the niche mechanism, by neither, or by both. We develop quantitative metrics of the relative importance of the two mechanisms. We also discuss the implications for the management of biodiversity in communities structured by the two mechanisms

Pulse switching for high energy lasers

A saturable inductor switch for compressing the width and sharpening the rise time of high voltage pulses from a relatively slow rise time, high voltage generator to an electric discharge gas laser (EDGL) also provides a capability for efficient energy transfer from a high impedance primary source to an intermediate low impedance laser discharge network. The switch is positioned with respect to a capacitive storage device, such as a coaxial cable, so that when a charge build-up in the storage device reaches a predetermined level, saturation of the switch inductor releases or switches energy stored in the capactive storage device to the EDGL. Cascaded saturable inductor switches for providing output pulses having rise times of less than ten nanoseconds and a technique for magnetically biasing the saturable inductor switch are disclosed

Multiplex electric discharge gas laser system

A multiple pulse electric discharge gas laser system is described in which a plurality of pulsed electric discharge gas lasers are supported in a common housing. Each laser is supplied with excitation pulses from a separate power supply. A controller, which may be a microprocessor, is connected to each power supply for controlling the application of excitation pulses to each laser so that the lasers can be fired simultaneously or in any desired sequence. The output light beams from the individual lasers may be combined or utilized independently, depending on the desired application. The individual lasers may include multiple pairs of discharge electrodes with a separate power supply connected across each electrode pair so that multiple light output beams can be generated from a single laser tube and combined or utilized separately

An NMR Study of Substituent Effects in Ortho-Substituted Aryl Methyl Sulfides

This 51 page thesis involved the synthesis of a series of ortho substituted methyl phenyl sulfides and the subsequent interpretation of their nmr spectra to see if a linear correlation of reported ortho sigma constants with carbon 13-proton coupling constants or S-methyl chemical shifts existed. It was also the object of this study to determine a new set of ortho substituent constants based upon these data

UNDERSTANDING LONG-TERM ENERGY USE AND CARBON DIOXIDE EMISSIONS IN THE USA

We compile a database of energy uses, energy sources, and carbon dioxide emissions for the USA for the period 1850-2002. We use a model to extrapolate the missing observations on energy use by sector. Overall emission intensity rose between 1850 and 1917, and fell between 1917 and 2002. The leading cause for the rise in emission intensity was the switch from wood to coal, but population growth, economic growth, and electrification contributed as well. After 1917, population growth, economic growth and electrification pushed emissions up further, and there was no net shift from fossil to non-fossil energy sources. From 1850 to 2002, emissions were reduced by technological and behavioural change (particularly in transport, manufacturing and households), structural change in the economy, and a shift from coal to oil and gas. These trends are stronger than electrification, explaining the fall in emissions relative to GDP.Carbon dioxide emissions, decomposition, environmental Kuznets curve, USA, history

The Phra Malai legend in Thai Buddhist literature: A study of three texts.

The story of the arhat Phra Malai and his visits to heaven and hell is often described as one of the most pervasive and influential themes in Thai Buddhism. The story exists in numerous and varied poetic and prose forms and is also depicted in painting and sculpture. However, the story has never been studied comprehensively in terms of the various contexts within which the different versions are recited. In this dissertation I have traced the background and development of the earliest known Thai version of this story from its Sri Lankan roots to its florescence in the northern Thai kingdom of Lan Na. I have suggested that the Lan Na version of Phra Malai, which is recited annually as a preface to the Vessantara Jataka, was introduced as a promotional text to encourage participation in the Vessantara Jataka festival. The recitation of this Jataka, I propose, was promoted as a means of preserving the Buddhist teachings, which according to an earlier prediction, would disappear in the 2000th year of Buddhism. I have also compared this early version of the story with two later versions from central Thailand. One of these is the highly literary Kham Luang, or royal version, which appears to have been written as a work of merit-making. The other is the popular colloquial Klon Suat or chanted version, which has provided edification, entertainment, and personal merit-making opportunities in for sermons, weddings, and funerals. Finally, I have translated and annotated the Kham Luang, which has not yet appeared in translation in a Western language. My study has demonstrated that the Phra Malai theme has been used in quite different contexts for different purposes. This flexibility as well as the story's recontextualization of Buddhist teachings into an accessible format account for its pervasiveness over the centuries.Ph.D.Art historyAsian literatureCommunication and the ArtsFolkloreLanguage, Literature and LinguisticsPhilosophy, Religion and TheologyReligionSocial SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/128920/2/9303697.pd

Combining Active Learning Strategies: Performances and Experiences of Grade School Filipino Students

This study combined computer simulation and predict-observe-explain as a new strategy known as Computer Simulation Supported Predict-Observe-Explain (CSSPOE) to explore other ways to facilitate the teaching and learning in physics. This strategy was tested in determining the conceptual understanding and scientific reasoning among grade school Filipino students. A quasi-experimental method was used to gather quantitative data from 38 participants then a case study was used to acquire information from the students. After the CSSPOE intervention, post-test results showed that students had positive conceptual changes, and this increase was significant. The interview data showed that participants pointed out the affordances of CSSPOE, such as visualization, autonomy, recognition of alternative conceptions, and consequently accommodating the scientific notions, and noticing the departure of the strategy from the usual lecture method. The recommendation is to adapt CSSPOE in the K to 12 science curriculum or even in college Physics classes. Physics teachers should strive to utilize constructivist and active learning approaches like CSSPOE

A theory of forest dynamics: Spatially explicit models and issues of scale

Good progress has been made in the first year of DOE grant (number sign) FG02-90ER60933. The purpose of the project is to develop and investigate models of forest dynamics that apply across a range of spatial scales. The grant is one third of a three-part project. The second third was funded by the NSF this year and is intended to provide the empirical data necessary to calibrate and test small-scale (less than or equal to 1000 ha) models. The final third was also funded this year (NASA), and will provide data to calibrate and test the large-scale features of the models