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Automated Low-cost Instrument for Measuring Total Column Ozone

Description: Networks of ground-based and satellite borne instruments to measure ultraviolet (UV) sunlight and total column ozone have greatly contributed to an understanding of increased amounts of UV reaching the surface of the Earth caused by stratospheric ozone depletion. Increased UV radiation has important potential effects on human health, and agricultural and ecological systems. Observations from these networks make it possible to monitor total ozone decreases and to predict ozone recovery trends due to global efforts to curb the use of products releasing chemicals harmful to the ozone layer. Thus, continued and expanded global monitoring of ozone and UV is needed. However, existing automatic stratospheric ozone monitors are complex and expensive instruments. The main objective of this research was the development of a low-cost fully automated total column ozone monitoring instrument which, because of its affordability, will increase the number of instruments available for ground-based observations. The new instrument is based on a high-resolution fiber optic spectrometer, coupled with fiber optics that are precisely aimed by a pan and tilt positioning mechanism and with controlling programs written in commonly available software platforms which run on a personal computer. This project makes use of novel low-cost fiber optic spectrometer technology. A cost advantage is gained over available units by placing one end of the fiber outdoors to collect sunlight and convey it indoors, thereby allowing the spectrometer and computer to be placed in a controlled environment. This reduces the cost of weatherproofing and thermal compensation. Cost savings also result from a simplified sun targeting system, because only a small pan and tilt device is required to aim the lightweight fiber optic ends. Precision sun-targeting algorithms, optical filter selection, and software to derive ozone from spectral measurements by the spectrometer are a major contribution of this project. This system is a flexible platform ...
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Date: May 2006
Creator: Nebgen, Gilbert Bernard
Partner: UNT Libraries

A Study of Soil Erosion and its Control in the United States with Special Reference to Texas

Description: A study of soil erosion in the United States, especially in Texas, which brings attention to the causes of soil erosion under the existing system of farm management. The material gathered and compiled and arranged under certail main heading. Two chapters deal with present and immediate causes of erosions and their results. One full chapter takes up the history of the conservation movement and attempts to show how slow Texans have been in comparison with some of the other states of the United States. The study calls for further research, teaching of better land-use, raising awareness of soil erosion causes and conditions.
Date: June 1939
Creator: Merrell, Jesse Byron
Partner: UNT Libraries

Regulation and Political Costs in the Oil and Gas Industry: An Investigation of Discretion in Reporting Earnings and Oil and Gas Reserves Estimates

Description: This study investigates the use of discretion by oil and gas companies in reporting financial performance and oil and gas reserve estimates during times of high political scrutiny resulting from increases in energy prices. Hypotheses tested in prior literature state that companies facing the risk of increasing taxes or new regulations reduce reported earnings to reduce this risk. This study uses a measure of high profitability (rank order of return on assets relative to industry peers) to identify oil and gas companies more likely to manage earnings during the period from 2002 to 2008. Two measures of discretionary accruals (total and current discretionary accruals), and a measure of discretionary depreciation, depletion, and amortization (DDA) were used as indicators of discretion exercised in reporting earnings. Data on oil and gas reserve disclosures was also hand-collected from Forms 10-K to investigate whether managers use reserve estimate revisions to reduce reported earnings through increasing the annual depletion expense. Results suggest that both oil and gas refining and producing firms use negative discretionary accruals to reduce reported earnings. Results also indicate that profitability is an important determinant of the use of negative discretionary accruals by these companies regardless of the time period examined. There is also evidence that oil and gas producing firms opportunistically revise their oil and gas reserve estimates to increase depreciation, depletion, and amortization expense during periods of high oil prices.
Date: August 2010
Creator: Kurdi, Ammr
Partner: UNT Libraries