Master of Engineering

<p>An evaluation of a Continuous Countercurrent Liquid-Liquid Extraction (CCLLE) system in conjunction with a Gas Chromatograph Mass Spectrometer for application in trace analysis of Synthetic Organic Compounds.</p> <p>An experiment is designed to test the extraction efficiency of the CCLLE system at less than 1ppb levels. Limitations of the CCLLE system are accessed.</p> <p> Experimental data associated with the extraction efficiency study is included.</p> / Master of Science

Master of Science

<p>This research addresses a two-dimensional stock cutting problem encountered at the New River Valley Workshop (NRV), Inc. in Radford, VA. This research considers recent literature on two-dimensional stock cutting techniques, pattern generating methods, solution approaches, and practical problem considerations in addressing the NRV cutting problem. Linear Programming analysis is applied to NRV's two-dimensional cutting problem. A computer-based implementation of the LP solution methodology is developed and used to solve NRV cutting problems. Test data and sample problems are used to demonstrate the efficiency, speed and accuracy of the computer-based system. Solution results from test data are compared to current NRV performance, illustrating the significant improvements in solution time and stock utilization that can be attained through the use of LP techniques and this computer-based implementation. / Master of Science

Master of Engineering

Master of Science

No description available.

No description available.

In traditional quality control charts, fixed sampling interval (FSI) schemes are used where the time between samples has fixed intervals. More efficient methods called variable sampling interval (VSI) schemes have been developed where one takes the next observation sooner than usual if there is an indication that the process is operating off the target value. Another traditional assumption behind most statistical process control charts is that the sequential observations are independent. However, there are many situations where the sequential observations should not to be treated as independent. Rather, a time series model, in particular the first order autoregressive (AR (1)) model, is appropriate. A Markov chain representation is used to study the properties of the FSI and VSI Shewhart X control charts. First, the results show that if the process variance is properly estimated and if traditional control limits are used in the FSI control charts, then the detection time is shorter when the consecutive observations are negatively correlated than when they are positively correlated. If they are positively correlated, then the false alarm rate decreases as the correlation between consecutive observations increases. On the other hand, the detection time increases as the correlation increases. In VSI control charts with traditional control limits, if the process mean is on or near the target, then the average time to signal (A TS) and average number of samples to signal (ANSS) tend to decrease as the correlation increases until the correlation becomes rather moderate. Then, for more highly correlated data, the A TS and ANSS tend to increase as the correlation increases. Next, the results show that, even under the AR (1) process, the VSI chart is more efficient than the FSI chart in terms of ATS. In contrast, the VSI chart is less efficient than the FSI chart in terms of ANSS. The efficiency (inefficiency) of ATS (ANSS) tends to decrease (increase) as the correlation between the consecutive observations becomes stronger. Steady state ATS (A TS·) and steady state ANSS (ANSSO) under the AR (1) process show the same trend as the 'regular' ATS and 'regular' ANSS except when the deviation is very large. If the deviation is very large, then the VSI control chart does not seem to be more efficient than the FSI control chart in terms of steady state ATS. If we have an AR (2) process, then for any given value of tP2 a PSI control chart has a shorter detection time when tPl is negative than when tPl is positive. In a FSI control chart, the effect of positive </>2 in addition to positive tPl is that the false alarm rate decreases even further and the detection time is even longer. / Ph. D.

This study involves a comprehensive examination of one book, Maya Angelou's autobiographical I Know Why Why the Caged Bird Sings, since it was first published in 1970. Recognized as an important literary work, the novel is used in many middle and secondary school classrooms throughout the united States. Additionally, the work often is challenged in public schools on the grounds of its sexual and/or racial content. The purpose of this study included establishing the importance of I Know Why the Caged Bird Sings as a significant literary work; documenting how and why the book is used in schools; recording the censorship history of the book and preparing a case study as an example of how censorship complaints can arise and how they can be handled. Additionally, this dissertation includes the interview responses of the book's author to various issues dealt with in this study. In this study, the researcher examined the reception of the book by reviewers at the time of publication and the literary criticism written about the book during the past twenty years. After examining the literary merits of the book, the researcher established the context in which the book came to be included in school classrooms. An historical account of the censorship challenges raised against the book is included. Finally, a case study is used as a point of reference to illustrate how a censorship challenge might come about when Maya Angelou's book is used in schools. / Ph. D.