Manufacturer [Sic] of Densified-Refuse Derived Fuel (d-RDF) Pellets and Methods for the Determination of d-RDF Pellet Densities (open access)

Manufacturer [Sic] of Densified-Refuse Derived Fuel (d-RDF) Pellets and Methods for the Determination of d-RDF Pellet Densities

There are 150 million tons of Municipal Solid Waste (MSW) annually produced in the United States, which is approximately equivalent to 150 million barrels of oil. MSW production is inexhaustible, and is increasing on an annual per capita basis of approximately three per cent. After controlling the moisture and adding a binder, the combustible portion of MSW was converted to pellets. The objects of this project were to 1) evaluate the binder, 2) prepare the pellets, and 3) evaluate the pellets with regard to density. The manufacture of pellets was conducted at the Naval Air Station, Jacksonville, Florida. The evaluation of the binders and the pellets was done at North Texas State University (NTSU). There were three procedures for measuring the density. The first, using water displacement, was from the American Society for Testing and Material (ASTM). The second, using wax coating, was also from ASTM. The third, using sharply-cut cylindrical pellets, was developed at NTSU.
Date: December 1986
Creator: Attili, Bassam Saleem
System: The UNT Digital Library
The Effect of Using Class Discussion as a Pre-Writing Activity in Teaching Composition to ESL Students (open access)

The Effect of Using Class Discussion as a Pre-Writing Activity in Teaching Composition to ESL Students

This study examines the effect of class discussion as a pre-writing activity on actual writing performance. The experiment was conducted with all the Level 3 and Level 4 students enrolled in the Intensive English Language Institute of North Texas State University in the Spring, 1986 semester. Cochrans C test was performed to test significant differences between groups at the beginning of this test. Multivariate analysis of variance tests were used to determine the treatment effect between and within groups, and a matched t-test was also utilized to analyze the difference within tests. Pearson product moment correlation coefficient was calculated to determine the relationship between the discussion activity score and the actual writing score. Analysis of covariance tests were used to determine which variance of discussion activities had greater effect on the actual writing score.
Date: December 1986
Creator: Bang, Hwa-Ja Park
System: The UNT Digital Library
Forecasting Quarterly Sales Tax Revenues: A Comparative Study (open access)

Forecasting Quarterly Sales Tax Revenues: A Comparative Study

The purpose of this study is to determine which of three forecasting methods provides the most accurate short-term forecasts, in terms of absolute and mean absolute percentage error, for a unique set of data. The study applies three forecasting techniques--the Box-Jenkins or ARIMA method, cycle regression analysis, and multiple regression analysis--to quarterly sales tax revenue data. The final results show that, with varying success, each model identifies the direction of change in the future, but does not closely identify the period to period fluctuations. Indeed, each model overestimated revenues for every period forecasted. Cycle regression analysis, with a mean absolute percentage error of 7.21, is the most accurate model. Multiple regression analysis has the smallest absolute percentage error of 3.13.
Date: August 1986
Creator: Renner, Nancy A. (Nancy Ann)
System: The UNT Digital Library
The Analysis of the Demand for Residential Water in the City of Denton (open access)

The Analysis of the Demand for Residential Water in the City of Denton

The main objective of this study is to analyze the demand for water in Denton. The data used for the study are obtained from the City of Denton Utilities Department, the Tax Appraisal District and government documents. The 121 households which have perfect ten years historical data of water consumption were selected to be the representatives of all households in Denton. The study reveals that the change in water consumption significantly relates to the change in marginal price. Furthermore, the weather variables also have strong effects on the water consumption, especially during summer. The coefficients of income and a "difference" variable are found to have the opposite sign but are not equal in magnitude. In fact, they should be equal in magnitude, but opposite in sign. While the estimated coefficients on all independent variables were highly significant statistically, the resulting coefficient on the house size variable was statistically insignificant in the model test. The results show that the difference variable is required in the model. It also had some effect on the water consumption. It is found that there is a small change in water consumption when the lot size is increased.
Date: December 1986
Creator: Sawangchareon, Dumrongchai
System: The UNT Digital Library
Estimating Residential Water Demand: a Case of Multiple-Part Tariff for Denton, Texas (open access)

Estimating Residential Water Demand: a Case of Multiple-Part Tariff for Denton, Texas

This paper analyzes the demand for water in case of a multiple-part tariff in Denton, Texas. The model used is developed from Billing & Agthe's model by using the following variables: marginal price, difference variable, tax assessed value, lot size, house size, temperature and rainfall.. The results indicate that temperature has the greatest effect on water demand, since this area is considered to be a very warm area. Also, marginal price seems to have a strong effect on water consumption indicating that customer is well-informed to a change in rate schedule. This test supports the original idea of the previous articles that the coefficient on difference variable and that on income should have the opposite sign. However, this test can not prove that those coefficients should be equal in magnitude, since the proxy of the income variable can not represent the individual monthly income. In addition, this article introduces another variable which can be a proxy of outdoor water use. That is lot size showing the effect on water demand. The last variable used in the model, house size,does not have much effect on water demand and is dropped out in the final model.
Date: December 1986
Creator: Wattanakuljarus, Voravit
System: The UNT Digital Library