" s1997 vau| sm 00| 0|eng d" (VPI) etd-3345131939761081 Walker, Gordon James Conceptual Development and Empirical Testing of an Outdoor Recreation Experience Model: The Recreation Experience Matrix (REM) Computer data - 5 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 1997 Thesis (PHD)--Virginia Polytechnic Institute and State University, 1997-03-31 Includes bibliographical references. This dissertation examines four issues, including: (a) whether outdoor recreation experiences not included in the Recreation Experience Preference (REP) scales exist; (b) whether these experiences can be categorized using a framework called the Recreation Experience Matrix (REM); (c) how well the Recreation Opportunity Spectrum (ROS) variables of activity, setting, and expertise explain the types of experiences outdoor recreationists receive; and (d) how well two new variables--primary mode and mode dependence--explain the types of experiences outdoor recreationists receive. In order to address these issues, an on-site questionnaire was distributed at Mount Rogers National Recreation Area in Virginia during October and November, 1995. A total of 410 people completed this questionnaire. Of these, 336 provided useable addresses for a follow-up mail-out questionnaire, with 169 (50.3%) actually returning it. After performing a variety of statistical analyses, it was found that: (a) some outdoor recreationists did report having non-REP experiences involving identity, cognition, absorption, and self-concept; (b) indirect support does exist for classifying outdoor recreation experiences using the REM framework; and (c) the ROS variables of activity, setting, and expertise, do explain some outdoor recreation experiences, as do the new variables of primary mode and mode dependence. System requirements: PC, World Wide Web Browser and PDF reader. Available electronically via Internet. outdoor recreation recreation experience preference scales recreation experience matrix recreation opportunity spectrum Virginia Tech Forestry Daniel R. Williams Committee Member K. Jill Kiecolt Committee Member Bradley R. Hertel Committee Member Joseph W. Roggenbuck Committee Co-Chair R. Bruce Hull Committee Co-Chair unrestricted http://scholar.lib.vt.edu/theses/available/etd-3345131939761081/ " s1997 vau| sm 00| 0|eng d" (VPI) etd-171110282975860 A'Hearn, Francis W. The Industrial College of the Armed Forces: Contextual Analysis of an Evolving Mission, 1924-1994 Computer data - 10 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 1997 Thesis (PHD)--Virginia Polytechnic Institute and State University, 1997-04-21 Includes bibliographical references. This study assessed the changing mission of the Industrial College of the Armed Forces as it evolved from the institution's founding as the Army Industrial College in 1924 to its 70th anniversary in 1994. The study drew heavily from archival materials in the Special Collections of the National Defense University in Washington, DC. The problem investigated in this research was to analyze how and why the institution's mission changed over time within the context of internal and external forces and events. Based upon the historical method of research, the study identified six periods in the institution's development over seven decades: its origins in the aftermath of World War I from 1918 to 1924; its growth in the interwar years, 1924 to 1940; the institution's temporary closure and subsequent reconstitution as the Industrial College of the Armed Forces during and after World War II, from 1940 to 1947; a formative period during the Cold War from 1947 to 1962; its continuing evolution throughout the Vietnam era from 1962 to 1974; and finally the College's modern development as a joint service educational institution from 1974 to 1994. The study found that the institution has changed dramatically over much of this century, just as the world and the country's national security concerns have changed profoundly in the same period. The mission of the College has evolved from a narrow focus on training military officers in procurement and industrial mobilization to that of a graduate institution dedicated to educating a select group of promising senior military and civilian officials in the political, economic, and resource dimensions of national security. Over time, the focus has shifted from training to education, from military to national issues, from internal and external educational programs to primarily internal ones, and from a predominant interest in domestic issues to an equally strong concern for international matters. The study finds that a variety of internal and external events and forces have impelled these changes. A wide range of influential individuals and stakeholders, bureaucratic power structures, governmental agencies, special review boards, and various political, economic, military, and social considerations have influenced the mission of the College. The study also concludes that several factors have likely contributed to the institution's relatively unusual longevity as a government entity. Its dual identity as an educational institution and a government organization set apart from the mainstream bureaucracy has had a favorable influence. So too has the institution been aided by the unique service it has provided to multiple customer constituencies. In fact, the College's mission has made it unique as an institution of adult education and learning in this country and perhaps the world. System requirements: PC, World Wide Web Browser and PDF reader. Available electronically via Internet. History Adult Education Armed Forces Virginia Tech Adult Education John Bokel Harold Stubblefield Committee Chair Marcie Boucouvalas Thomas Hunt Albert Wiswell unrestricted http://scholar.lib.vt.edu/theses/available/etd-171110282975860/ " s2000 vau| sm 00| 0|eng d" (VPI) etd-05012000-14030054 Bell, Tannisha D. An Examination of Race and Recurrent Substance Problems in the United States Computer data - 1 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 2000 Thesis (MS)--Virginia Polytechnic Institute and State University, 2000-04-17 Includes bibliographical references. Several studies show that African-Americans are less likely than whites to use alcohol or drugs. However, if African-Americans use drugs then they are more likely to become heavy and persistent users. African-Americans are also more likely to have a current substance abuse disorder. There is not much in the literature to explain this phenomenon. The purpose of this study is to examine the alcohol and drug abuse, use and dependence of blacks and whites in order to explain the differences in the course of the substance disorder, using data from the National Comorbidity Survey. There are many variables thought to contribute to the racial difference, such as socio-economic status (measured by income and education), religion, insurance, employment status, and marital status. The data in this literature indicate that the aforementioned variables do not explain the racial difference in substance disorders. However, after performing interaction analyses, it is clear that the effects of treatment are different for blacks and whites. Treatment is more effective for whites, and it may even cause the substance disorder to become worse for blacks. Several studies indicate that this may be the result of cultural differences between the treatment staff and the clients. System requirements: PC, World Wide Web Browser and PDF reader. Available electronically via Internet. African-Americans Drugs Substance Abuse Race Virginia Tech Sociology Clifton Bryant Committee Member Donald Shoemaker Committee Co-Chair Michael Hughes Committee Co-Chair restricted http://scholar.lib.vt.edu/theses/available/etd-05012000-14030054/ " s1997 vau| sm 00| 0|eng d" (VPI) etd-3621112139711101 Ahmad, Syed Alwi B. Fermion Quantum Field Theory In Black-hole Spacetimes Computer data - 1 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 1997 Thesis (PHD)--Virginia Polytechnic Institute and State University, 1997-04-18 Includes bibliographical references. The need to construct a fermion quantum field theory in black-hole spacetimes is an acute one. The study of gravitational collapse necessitates the need of such. In this dissertation, we construct the theory of free fermions living on the static Schwarzschild black-hole and the rotating Kerr black-hole. The construction capitalises upon the fact that both black-holes are stationary axisymmetric solutions to Einstein's equation. A factorisability ansatz is developed whereby simple quantum modes can be found, for such stationary spacetimes with azimuthal symmetry. These modes are then employed for the purposes of a canonical quantisation of the corresponding fermionic theory. At the same time, we suggest that it may be impossible to extend a quantum field theory continuously across an event horizon. This split of a quantum field theory ensures the thermal character of the Hawking radiation. In our case, we compute and prove that the spectrum of neutrinos emitted from a black-hole via the Hawking process is indeed thermal. We also study fermion scattering amplitudes off the Schwarzschild black-hole. System requirements: PC, World Wide Web Browser and PDF reader. Available electronically via Internet. General Relativity Quantum Field Theory Virginia Tech Physics Lay Nam Chang Committee Chair M. Blecher T. Mizutani B.K. Dennison T. Takeuchi unrestricted http://scholar.lib.vt.edu/theses/available/etd-3621112139711101/ " s1997 vau| sm 00| 0|eng d" (VPI) etd-133422039701091 Anderson, Alaric Lee Investigation of Steel Joist Supported Wood Floor Systems Computer data - 6 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 1997 Thesis (MS)--Virginia Polytechnic Institute and State University, 1997-02-01 Includes bibliographical references. This study investigates four aspects associated with steel joist supported wood floor systems: 1) acceptability, 2) prediction of deflection, 3) prediction of frequency, and 4) effects of diagonal bracing. Six full scale floor systems and two two-joist floor systems were constructed in the laboratory. Span length, joist spacing and diagonal bracing were the only parameters modified for each floor. Four tests were performed for each floor setup: heel drop impact, walking perpendicular and parallel to the floor joists, static concentrated load at midspan, and testing to determine subjective evaluation. Five acceptability criteria were investigated: Swedish Building Technology Design Guide, Australian Standard Domestic Metal Framing Code, Canadian Timber Floor Criterion, Murray's Criterion, and Johnson's Criterion. The results from these criteria were compared to the measured results of each floor system. Four methods to predict vertical deflection due to a static load at midspan were compared to measured values of each floor system. The effect of diagonal bracing on floor stiffness was also investigated. Results and concusions were made for each aspect investigated. System requirements: PC, World Wide Web Browser and PDF reader. Available electronically via Internet. none Virginia Tech Civil Engineering T. M. Murray Committee Chair R. H. Plaut None T. E. Cousins None unrestricted http://scholar.lib.vt.edu/theses/available/etd-133422039701091/ " s1997 vau| sm 00| 0|eng d" (VPI) etd-23281533974920 Ackley, John A. Weed Management Programs in Potato, Transplanted Tomato and Transplanted Pepper with Rimsulfuron and Other Herbicides Computer data - 1 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 1997 Thesis (PHD)--Virginia Polytechnic Institute and State University, 1997-03-31 Includes bibliographical references. Weed management programs in ŒSuperior' potato with PRE and POST rimsulfuron treatments were investigated during 1992, 1993, and 1994. Common ragweed control by PRE combinations of metolachlor with linuron or metribuzin was higher when treatments included PRE or POST rimsulfuron. Common lambsquarters control was 93 to 96% by treatments that included POST rimsulfuron. Applications of 35 g ai/ha rimsulfuron plus 280 g ai/ha metribuzin POST controlled weeds comparable to sequential applications. Potato recovered from occasional injury caused by rimsulfuron, rimsulfuron plus metribuzin, and organophosphate insecticides combined POST with rimsulfuron plus metribuzin. Several acetolactate synthase (ALS)-inhibiting herbicides were evaluated for yellow nutsedge control in the greenhouse. Herbicides were applied POST to yellow nutsedge at actual or anticipated commercial rates. Yellow nutsedge control was 92 and 71% from halosulfuron and chlorimuron, respectively. Control ranged from 48 to 69% from primisulfuron, pyrithiobac, and rimsulfuron. Control from nicosulfuron and imazethapyr was 45 and 68%, respectively, while thifensulfuron and CGA-152005 had almost no activity on yellow nutsedge. Chlorimuron, imazethapyr, and halosulfuron were the only herbicides which reduced yellow nutsedge regrowth., Rrimsulfuron was evaluated in tomato at 26 and 35 g ai/ha, sequentially at 26 g/ha, at 26 g/ha plus metribuzin at 280 g ai/ha, and metribuzin at 280 g/ha were evaluated POST for weed control in transplanted ŒAgriset' tomato. Common lambsquarters was controlled by rimsulfuron at 35 g/ha. Rimsulfuron plus metribuzin gave consistent control of common ragweed but jimsonweed and goosegrass control was generally low. Rimsulfuron treatments caused < 12% injury to tomato. Tomato yield was consistently high in the metribuzin, metribuzin plus rimsulfuron, and rimsulfuron sequential treatments. In greenhouse studies, giant foxtail and large crabgrass control by rimsulfuron was above 95 and 85% respectively, but goosegrass was not controlled. Height of four tomato cultivars was not reduced, but dry weight of ŒFloradade' and ŒSunbeam' was reduced by rimsulfuron. In 1993, 1994 and 1995, PPI clomazone at 390 g ai/ha, POST rimsulfuron at 35 g ai/ha, and PPI trifluralin at 560 g ai/ha were evaluated for weed control in transplanted ŒKeystone RG3' bell pepper. Common lambsquarters and jimsonweed control was highest by clomazone treatments, while common ragweed control was low from all treatments. Keystone RG3 in the field and greenhouse and ŒCamelot', ŒJupiter' and ŒMemphis' in the greenhouse were injured by POST rimsulfuron and had lower height and dry weight than untreated controls. In the greenhouse, black nightshade control was below 23% and jimsonweed control was below 49% by rimsulfuron POST. The absorption, translocation, and metabolism of rimsulfuron was investigated in three Solanaceous weed species. Rimsulfuron uptake did not differ between black nightshade and eastern black nightshade while less labeled herbicide was absorbed by hairy nightshade. Black and eastern black nightshade translocated up to 50% of the labeled herbicide out of the treated leaf with 40 to 50% of the herbicide being moved to the actively growing regions of the plant. In hairy nightshade, an average 40% of the labeled herbicide was moved out of the treated leaf and less than 30% of the translocated herbicide was moved basipetally. Most major metabolites were apparent at 24 and 48 hours however, there were no differences in metabolite composition. Rimsulfuron will be an effective herbicide for use in weed management programs in potatoand tomato, however rimsulfuron causes too much injury in pepper to be used. System requirements: PC, World Wide Web Browser and PDF reader. Available electronically via Internet. clomazone metribuzin trifluralin pepper potato rimsulfuron nightshade tomato Virginia Tech Plant Pathology, Physiology, and Weed Science Henry P. Wilson Committee Chair E. Scott Hagood None John Hess None Kriton K. Hatzios None Ronald D. Morse None unrestricted http://scholar.lib.vt.edu/theses/available/etd-23281533974920/ " s1997 vau| sm 00| 0|eng d" (VPI) etd-123322282975860 Adams, Nicole An Ongoing Dialogue Computer data - 1 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 1997 Thesis (MA)--Virginia Polytechnic Institute and State University, 1997-02-03 Includes bibliographical references. This thesis is an attempt to reconcile the form of an idea with the form of a thing in this world to be experienced. An exploration of the meaning behind the words idea, form, making and experience begins to unite the intellect of an architect with the design of an architect. The terms are defined in the thesis and explained through the project. The thesis through the project sets out to take these terms beyond mere words and give them an opportunity to inform eachother. It is this dialectic between idea, form, making and experience that I believe to be the heart of architecture. Idea and form are inextricably tied to one another. đWhich is the origin of the other?ø is not as pertinent a question as đhow do the two inform each other?ø. Ideas change from project to project as do the forms inherent in those ideas. Preceeding both idea and material form is another type of form that is immaterial and often remains unseen. It is the character which is essential to a thing. Whether it be a place or an object, it is the quality in the thing itself. This character is the instigator of idea and form. It is the architect£s goal to make this inherent form perceivable. An architect makes idea and form manifest through a concept of making. In Notes for a Theory of Making in a Time of Necessity, Giuseppe Zambonini emphasizes that đWe must look not only at the quality of the material used and at the craft employed, but also at the quality of the thought process selecting and shaping the material. . .quality cannot be an intrinsic condition that belongs to the object . . . but rather it must express the intent by which it is created and therein the clarity and strength of the meaning being produced by its formø (Zambonini, 21). This quality of design can best be achieved the earlier making and materiality are involved in the design process. The questions of đwhat is the form of this idea?ø and đhow is this form to be made?ø begin the relationship between idea, form and making. The immediate responses may be intuitive, but the final one is the resultof numerous makings. This is why architecture is practiced. When the question arises:đhow can this form not only embody an idea but be the idea?ø, the dialogue takes on a greater import. The way in which a thing will be experienced starts to inform its making. đIt is the process that will engage both user and observer in an active, participating relationship with the work and thereby give the work its meaningø (Zambonini, 21). It is at this point that the dialectic is fully engaged. These four aspects simultaneously inform each other and nurture the project throughout its life, from drawing board, to construction to the various experiences that it will impart. It is not just one aspect, but these four in communion that are the architecture. System requirements: PC, World Wide Web Browser and PDF reader. Available electronically via Internet. none Virginia Tech Architecture William Brown V. Hunter Pittman Frank Weiner unrestricted http://scholar.lib.vt.edu/theses/available/etd-123322282975860/ " s1997 vau| sm 00| 0|eng d" (VPI) etd-255314202974780 Al-Yakoob, Salem Mohammed Mixed-Integer Mathematical Programming Optimization Models and Algorithms For An Oil Tanker Routing and Scheduling Problem Computer data - 1 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 1997 Thesis (PHD)--Virginia Polytechnic Institute and State University, 1997-02-27 Includes bibliographical references. This dissertation explores mathematical programming optimization models and algorithms for routing and scheduling ships in a maritime transportation system. Literature surveyed on seaborne transportation systems indicates that there is a scarcity of research on ship routing and scheduling problems. The complexity and the overwhelming size of a typical ship routing and scheduling problem are the primary reasons that have resulted in the scarcity of research in this area. The principal thrust of this research effort is focused at the Kuwait Petroleum Corporation (KPC) Problem. This problem is of great economic significance to the State of Kuwait, whose economy has been traditionally dominated to a large extent by the oil sector. Any enhancement in the existing ad-hoc scheduling procedure has the potential for significant savings. A mixed-integer programming model for the KPC problem is constructed in this dissertation. The resulting mathematical formulation is rather complex to solve due to (1) the overwhelming problem size for a typical demand contract scenario, (2) the integrality conditions, and (3) the structural diversity in the constraints. Accordingly, attempting to solve this formulation for a typical demand contract scenario without resorting to any aggregation or partitioning schemes is theoretically complex and computationally intractable. Motivated by the complexity of the above model, an aggregate model that retains the principal features of the KPC problem is formulated. This model is computationally far more tractable than the initial model, and consequently, it is utilized to construct a good quality heuristic solution for the KPC problem. The initial formulation is solved using CPLEX 4.0 mixed integer programming capabilities for a number of relatively small-sized test cases, and pertinent results and computational difficulties are reported. The aggregate formulation is solved using CPLEX 4.0 MIP in concert with specialized rolling horizon solution algorithms and related results are reported. The rolling horizon solution algorithms enabled us to handle practical sized problems that could not be handled by directly solving the aggregate problem. The performance of the rolling horizon algorithms may be enhanced by increasing the physical memory, and consequently, better solutions can be extracted. The potential saving and usefulness of this model in negotiation and planning purposes strongly justifies the acquisition of more computing power to tackle practical sized test problems. An ad-hoc scheduling procedure that is intended to simulate the current KPC scheduling practice is presented in this dissertation. It is shown that results obtained via the proposed rolling horizon algorithms are at least as good, and often substantially better than, results obtained via this ad-hoc procedure System requirements: PC, World Wide Web Browser and PDF reader. Available electronically via Internet. ship scheduling aggregation mixed-integer programming Virginia Tech Mathematics H. Sherali Committee Chair T. Herdman None R. Wheeler None J. Burns None L. Johnson None restricted http://scholar.lib.vt.edu/theses/available/etd-255314202974780/ " s1997 vau| sm 00| 0|eng d" (VPI) etd-335713312971890 Appel, Justin Ronald Sensitivity Calculations For Conservation Laws With Application To Discontinuous Fluid Flows Computer data - 1 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 1997 Thesis (PHD)--Virginia Polytechnic Institute and State University, 1997-03-14 Includes bibliographical references. Flow sensitivities are the derivatives of the variables that describe the fluid flow with respect to the parameters that determine the fluid flow. Sensitivities are of interest in their own right and are also of use in flow optimization, control and design and in the calculation of perturbed flows. Problems arise in all sensitivity calculation methods in the presence of discontinuities and other complexities such as shock waves, contact discontinuities and rarefaction waves that commonly occur in super and hypersonic inviscid, compressible fluid flows. Flow sensitivities are calculated using finite difference quotients, automatic differentiation and the sensitivity equation method for a variety of numerical methods. Explanations for the inaccuracies arising in the numerical approximations and implications these inaccuracies have on different applications are discussed. Possible corrections for the inaccuracies are outlined. System requirements: PC, World Wide Web Browser and PDF reader. Available electronically via Internet. none Virginia Tech Mathematics Max D. Gunzburger Committee Chair John A. Burns None Eugene M. Cliff None Terry L. Herdman None Janet S. Peterson None unrestricted http://scholar.lib.vt.edu/theses/available/etd-335713312971890/ " s1996 vau| sm 00| 0|eng d" (VPI) etd-104722369631841 Aliftiras, George Receiver Implementations for a CDMA Cellular System Computer data - 2 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 1996 Thesis (MS)--Virginia Polytechnic Institute and State University, 1996-07-01 Includes bibliographical references. The communications industry is experiencing an explosion in the demand for personal communications services (PCS). Several digital technologies have been proposed to replace overburdened analog systems. One system that has gained increasing popularity in North America is a 1.25 MHz Code Division Multiple Access (CDMA) system (IS-95). In CDMA systems, multiple access interference limits the capacity of any system using conventional single user correlation or matched filter receivers. Previous research has shown that multiuser detection receivers that employ interference cancellation techniques can significantly improve the capacity of a CDMA system. This thesis studies two such structures: the successive interference cancellation scheme and the parallel interference cancellation scheme. These multiuser receivers are integrated into an IS-95 compatible receiver model which is simulated in software. This thesis develops simulation software that simulates IS-95 with conventional and multiuser receivers in multipath channels and when near-far conditions exist. Simulation results present the robustness of multiuser receivers to near-far in a practical system. In addition to multiuser implemenations, quantization effects from finite bit analog to digital converters (ADC) in CDMA systems will also be simulated. System requirements: PC, World Wide Web Browser and PDF reader. Available electronically via Internet. multiuser receiver CDMA interference cancellation quantization Virginia Tech Electrical and Computer Engineering Dr. Brian D. Woerner Committee Chair Dr. Theodore S. Rappaport Committee Member Dr. Charles W. Bostian Committee Member unrestricted http://scholar.lib.vt.edu/theses/available/etd-104722369631841/ " s1997 vau| sm 00| 0|eng d" (VPI) etd-831102339731121 Bethard, Greg L. A Microcomputer Simulation to Evaluate Management Strategies For Rearing Dairy Replacements. Computer data - 1 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 1997 Thesis (PHD)--Virginia Polytechnic Institute and State University, 1997-04-18 Includes bibliographical references. A microcomputer simulation was developed as a tool for analyzing the dairy replacement enterprise. The simulation was constructed using a spreadsheet, and equations were developed using stepwise regression procedures. The simulation predicted BW, DMI, and fixed and variable costs for each week of a heifer£s life from birth to calving. After calving, milk yield, feed costs, and fixed costs were predicted for first lactation. Variation was estimated for each predicted variable, thus enabling normal distribution of predicted values. The simulation was used to analyze profitability of various growth rate scenarios and marginal costs associated with changing feed costs, heat detection efficiency, death loss, and abortion rate. For the growth rate analysis, six scenarios were evaluated: 1) normal growth from 5 wk to calving, 2) accelerated growth from 5 wk to calving, 3) slow growth from 5 wk to calving, 4) normal growth from 5 wk to 14 mo and accelerated growth from 14 mo to calving, 5) accelerated growth from 5 wk to 14 mo and control growth from 14 mo to calving, and 6) slow growth from 5 wk to 14 mo and accelerated growth from 14 mo to calving. Average daily gain from birth to calving was 0.78, 0.90, 0.62, 0.78, 0.75, and 0.80 kg/d, and age at calving was 25.1, 23.1, 27.4, 23.1, 23.0, and 23.1 mo, respectively. Total rearing cost from birth to calving was 1246, 1220, 1275, 1148, 1148, and 1138 $/heifer, and net profit through first lactation was 399, 407, 319, 441, 432, and 463 $/heifer, respectively. Results suggest modest growth rates from birth to calving (0.75 to 0.80 kg/d) with reduced first calving age (<24 mo) is most desirable, and delayed calving (>24 mo) is costly and merits higher growth rates with earlier breeding. Increasing feed costs, death loss at birth through weaning, or abortion rate one percentage point increased rearing costs 7.33, 2.40, and 9.10 $/heifer. Improving heat detection efficiency one percentage point reduced rearing costs $2.80/heifer. For the heat detection analysis, the relationship between age at first calving and total rearing costs was -584.38 + 73.49 x calving age in mo (R-squared = 0.97), for ages at first calving from 24.4 to 26.6 mo. Results of this research agree with field observations that managers should strive for early calving (<24 mo) and modest growth rates (0.75 to 0.80 kg/d) to maximize profitability of the replacement enterprise. In addition, death loss, abortion rate, and heat detection efficiency are variables that a manager must control to minimize heifer rearing costs. System requirements: PC, World Wide Web Browser and PDF reader. Available electronically via Internet. dairy simulation model heifer Virginia Tech Dairy Science Carl E. Polan Thomas L. Bailey Robert E. James Committee Chair Charles C. Stallings Michael L. McGilliard unrestricted http://scholar.lib.vt.edu/theses/available/etd-831102339731121/ " s1997 vau| sm 00| 0|eng d" (VPI) etd-454016449701231 Allan, James P. The British Labour Party in Opposition, 1979-1997: Structures, Agency, and Party Change Computer data - 10 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 1997 Thesis (MA)--Virginia Polytechnic Institute and State University, 1997-04-24 Includes bibliographical references. The British Labour Party has spent eighteen years in opposition since 1979. During that time it lost four consecutive general elections to the Conservative Party. In 1997, however, it now looks set to win its first election since 1974. This thesis examines the Labour Party in opposition since 1979, using a theoretical framework informed by Anthony Giddens' structuration theory. Based on a dialectical notion of the structure and agency linkage, a two-tiered framework is constructed which at one level views a political party as consisting of a set of structures which can constrain and enable party leaders in their attempts to make the party electorally successful, and at another level the party is regarded as a collective agent in its own right, which in turn is subject to the effects of larger external structures. By comparing the strategies adopted by the Labour Party and its leaders since 1979, the thesis demonstrates that the apparent recovery in the Party's electoral fortunes has corresponded with an increase in the ability of agents to successfully negotiate structural constraints, whilst taking advantage of enabling structures. However, it is also clear that the transformation of Labour into an electorally viable party in 1997 is not solely the product of agency in the period since the last election; rather, it is the culmination of a longer-term process of party change. System requirements: PC, World Wide Web Browser and PDF reader. Available electronically via Internet. electoral performance The Labour Party structure and agency Virginia Tech Political Science Charles L. Taylor Committee Chair Stephen K. White Committee Member Rebecca H. Davis Committee Member unrestricted http://scholar.lib.vt.edu/theses/available/etd-454016449701231/ " s1997 vau| sm 00| 0|eng d" (VPI) etd-3034112939721181 Barake, Taha Mohamed A Generalized Analysis of Multiple-Clad Fibers with Arbitrary Step-Indx Profiles and Applications Computer data - 1 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 1997 Thesis (MS)--Virginia Polytechnic Institute and State University, 1997-04-22 Includes bibliographical references. A generalized analysis of multiple-clad cylindrical dielectric structures with step-index profiles is presented. This analysis yields unified expressions for fields, dispersion equation and cutoff conditions for weakly guiding optical fibers with step-index but otherwise arbitrary profiles. The formulation focuses on triple-clad fibers, but can accommodate single and double-clad fibers as special limiting cases. Using the generalized solutions, transmission properties of several types of specialty fibers for broadband applications, including dispersion-shifted, dispersion-flattened, and dispersion compensating fibers, are studied. Improved designs for dispersion-shifted and dispersion compensating fibers are achieved. Fiber parameters and material compositions for the improved designs are provided. The proposed design for the dispersion-shifted fiber yields zero second-order as well as third-order dispersion at the 1.55 micrometer wavelength. The dispersion compensating fiber proposed here provides a large negative dispersion of about -400 ps/nm.km at the 1.55 micrometer wavelength for the fundamental mode. Numerical results for dispersion characteristics, cutoff wavelengths, and radial field distributions are provided. System requirements: PC, World Wide Web Browser and PDF reader. Available electronically via Internet. multiple-clad fibers dispersion-altered fibers Virginia Tech Electrical and Computer Engineering Dr. Lee Johnson Dr. Ioannis M. Besieres Dr. Ahmad Saffai-Jazi Committee Chair unrestricted http://scholar.lib.vt.edu/theses/available/etd-3034112939721181/ " s1996 vau| sm 00| 0|eng d" (VPI) etd-522014589642481 Almajdoub, Salahuddin A. A Design Methodology for Physical Design for Testability Computer data - 2 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 1996 Thesis (PHD)--Virginia Polytechnic Institute and State University, 1996-07-01 Includes bibliographical references. Physical design for testability (PDFT) is a strategy to design circuits in a way to avoid or reduce realistic physical faults. The goal of this work is to define and establish a speci c methodology for PDFT. The proposed design methodology includes techniques to reduce potential bridging faults in complementary metal-oxide-semiconductor (CMOS) circuits. To compare faults, the design process utilizes a new parameter called the fault index. The fault index for a particular fault is the probability of occurrence of the fault divided by the testability of the fault. Faults with the highest fault indices are considered the worst faults and are targeted by the PDFT design process to eliminate them or reduce their probability of occurrence. An implementation of the PDFT design process is constructed using several new tools in addition to other "off-the-shelf" tools. The first tool developed in this work is a testability measure tool for bridging faults. Two other tools are developed to eliminate or reduce the probability of occurrence of bridging faults with high fault indices. The row enhancer targets faults inside the logic elements of the circuit, while the channel enhancer targets faults inside the routing part of the circuit. To demonstrate the capabilities and test the eff ectiveness of the PDFT design process, this work conducts an experiment which includes designing three CMOS circuits from the ISCAS 1985 benchmark circuits. Several layouts are generated for every circuit. Every layout, except the rst one, utilizes information from the previous layout to minimize the probability of occurrence for faults with high fault indices. Experimental results show that the PDFT design process successfully achieves two goals of PDFT, providing layouts with fewer faults and minimizing the probability of occurrence of hard-to-test faults. Improvement in the total fault index was about 40 percent in some cases, while improvement in total critical area was about 30 percent in some cases. However, virtually all the improvements came from using the row enhancer; the channel enhancer provided only marginal improvements. System requirements: PC, World Wide Web Browser and PDF reader. Available electronically via Internet. Bridging Faults The Labour Party Structure and Agency IDDQ Testing Electoral Performance Physical Design for Testability Virginia Tech Electrical and Computer Engineering Charles L. Taylor Committee Chair Rebecca H. Davis Committee Member Stephen K. White Committee Member Scott F. Midkiff Committee Chair James R. Armstrong Committee Member Hanif D. Sherali Committee Member Aicha A. Elshabini-Riad Committee Member Joseph G. Tront Committee Member unrestricted http://scholar.lib.vt.edu/theses/available/etd-522014589642481/ " s1996 vau| sm 00| 0|eng d" (VPI) etd-274210359611541 Atalla, Mauro J. Model Updating Using Neural Networks Computer data - 1 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 1996 Thesis (PHD)--Virginia Polytechnic Institute and State University, 1996-04-01 Includes bibliographical references. Accurate models are necessary in critical applications. Key parameters in dynamic systems often change during their life cycle due to repair and replacement of parts or en- vironmental changes. This dissertation presents a new approach to update system models, accounting for these changes. The approach uses frequency domain data and a neural net- work to produce estimates of the parameters being updated, yielding a model representative of the measured data. Current iterative methods developed to solve the model updating problem rely on min- imization techniques to nd the set of model parameters that yield the best match between experimental and analytical responses. Since the minimization procedure requires a fair amount of computation time, it makes the existing techniques infeasible for use as part of an adaptive control scheme correcting the model parameters as the system changes. They also require either mode shape expansion or model reduction before they can be applied, introducing errors in the procedure. Furthermore, none of the existing techniques has been applied to nonlinear systems. The neural network estimates the parameters being updated quickly and accurately without the need to measure all degrees of freedom of the system. This avoids the use of mode shape expansion or model reduction techniques, and allows for its implementation as part of an adaptive control scheme. The proposed technique is also capable of updating weakly nonlinear systems. Numerical simulations and experimental results show that the proposed method has good accuracy and generalization properties, and it is therefore, a suitable alternative for the solution of the model updating problem of this class of systems. System requirements: PC, World Wide Web Browser and PDF reader. Available electronically via Internet. adaptive control neural networks model updating Virginia Tech Engineering Science and Mechanics Daniel J. Inman Committee Chair Harry H. Robertshaw Ali H. Nayfeh Ronald D. Kriz O. H. Griffin, Jr. unrestricted http://scholar.lib.vt.edu/theses/available/etd-274210359611541/ " s1997 vau| sm 00| 0|eng d" (VPI) etd-3210192049721391 Bail, Thomas R. A Disturbance-Rejection Problem for a 2-D Airfoil Exhibiting Flutter Computer data - 1 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 1997 Thesis (MS)--Virginia Polytechnic Institute and State University, 1997-04-21 Includes bibliographical references. Flutter suppression is a problem of considerable interest in modern avionics. Flutter is a vibration caused by energy in the airstream being absorbed by a non-rigid wing. Active control is one possible method of suppressing flutter. However, due to unmeasurable aerodynamic-lag states, developing an active control using full-state feedback is not viable. The use of a state-estimator is a more practical way of developing active controllers. In this paper we investigate two control methods using state-estimators. We also use simple models of disturbances to test attenuation and robustness of each control method. Finally, a method of quantitative robust analysis is reviewed and then applied to each of the controlled systems. System requirements: PC, World Wide Web Browser and PDF reader. Available electronically via Internet. LQG H flutter singular values Virginia Tech Mathematics Dr. Terry Herdman Dr. Robert Rogers Dr. John Burns Committee Chair unrestricted http://scholar.lib.vt.edu/theses/available/etd-3210192049721391/ " s1996 vau| sm 00| 0|eng d" (VPI) etd-0521318109613220 Fleming, Todd B. Improving the Performance of the world Wide Web over Wireless Networks Computer data - 1 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 1996 Thesis (MS)--Virginia Polytechnic Institute and State University, 1996-11-04 Includes bibliographical references. The World Wide Web (WWW) has become the largest source of Internet traffic, but it was not designed for wireless networks. Documents with large inline images take a long time to fetch over low-bandwidth wireless networks. Radio signal dropouts cause file transfers to abort; users have to restart file transfers from the beginning. Dropouts also prevent access to documents that have not yet been visited by the user. All of these problems create user frustration and limit the utility of the WWW and wireless networks. In this work, a new Wireless World Wide Web (WWWW) proxy server and protocol were developed that address these problems. A client based on NCSA Mosaic connects to the proxy server using the new protocol, Multiple Hypertext Stream Protocol (MHSP). The proxy prefetches documents to the client, including inline images. The proxy also reduces the resolution of large bitmaps to improve performance over slow links. MHSP provides the ability to resume file transfers when the link has been broken then reestablished. The WWWW system was tested and evaluated by running script-controlled clients on different emulated network environments. This new system decreased document load time an average of 32 to 37 percent, depending on network configuration. System requirements: PC, World Wide Web Browser and PDF reader. Available electronically via Internet. wireless networks WWW MHSP proxy threads protocols Virginia Tech Electrical and Computer Engineering Scott F. Midkiff Committee Chair Nathaniel J. Davis F. Gail Gray unrestricted http://scholar.lib.vt.edu/theses/available/etd-0521318109613220/ " s1996 vau| sm 00| 0|eng d" (VPI) etd-310141259631631 Batongbacal, Alan L. A User-Extensible Architecture for Visualization and Analysis of Time-Series Trace Data Computer data - 1 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 1996 Thesis (MS)--Virginia Polytechnic Institute and State University, 1996-04-01 Includes bibliographical references. This thesis describes the design and implementation of Chitra95, a software system developed for the visualization and analysis of time-series trace data. Chitra95 is based upon two earlier generations of Chitra and is aimed at producing a system with broad applicability and utility in this area of research. This thesis contributes to the area of software design for trace visualization and analysis by proposing a set of design principles towards achieving the goals of system extensibility, reusability, reliability, testability and verifiability. These design principles are demonstrated by Chitra95, a software architecture proposed in this thesis for visualization and analysis of time-series trace data. This architecture is novel in its combination of independence from problem domain semantics; optimization for user-extensibility and code reusability; freedom from any specific user interface model; ability to simultaneously produce an integrated application and a reusable toolkit of parts that may either be customized into a turnkey system or integrated into other software systems; support for enhanced reliability, testability and verifiability; and support for an interface to the World Wide Web and for remote execution. Finally, this thesis makes the specific contribution of a data structure for representing large traces that permits the maintainance of multiple versions of a trace and retains the ability to undo modifications made to a trace. System requirements: PC, World Wide Web Browser and PDF reader. Available electronically via Internet. none Virginia Tech Computer Science Prof. Marc Abrams Committee Chair Prof. Dennis Kafura None Prof. Sallie Henry None unrestricted http://scholar.lib.vt.edu/theses/available/etd-310141259631631/ " s1996 vau| sm 00| 0|eng d" (VPI) etd-12164379662151 Battermann, Astrid Preconditioning of Karush--Kuhn--Tucker Systems arising in Optimal Control Problems Computer data - 1 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 1996 Thesis (MS)--Virginia Polytechnic Institute and State University, 1996-06-14 Includes bibliographical references. This work is concerned with the construction of preconditioners for indefinite linear systems. The systems under investigation arise in the numerical solution of quadratic programming problems, for example in the form of Karush--Kuhn--Tucker (KKT) optimality conditions or in interior--point methods. Therefore, the system matrix is referred to as a KKT matrix. It is not the purpose of this thesis to investigate systems arising from general quadratic programming problems, but to study systems arising in linear quadratic control problems governed by partial differential equations. The KKT matrix is symmetric, nonsingular, and indefinite. For the solution of the linear systems generalizations of the conjugate gradient method, MINRES and SYMMLQ, are used. The performance of these iterative solution methods depends on the eigenvalue distribution of the matrix and of the cost of the multiplication of the system matrix with a vector. To increase the performance of these methods, one tries to transform the system to favorably change its eigenvalue distribution. This is called preconditioning and the nonsingular transformation matrices are called preconditioners. Since the overall performance of the iterative methods also depends on the cost of matrix--vector multiplications, the preconditioner has to be constructed so that it can be applied efficiently. The preconditioners designed in this thesis are positive definite and they maintain the symmetry of the system. For the construction of the preconditioners we strongly exploit the structure of the underlying system. The preconditioners are composed of preconditioners for the submatrices in the KKT system. Therefore, known efficient preconditioners can be readily adapted to this context. The derivation of the preconditioners is motivated by the properties of the KKT matrices arising in optimal control problems. An analysis of the preconditioners is given and various cases which are important for interior point methods are treated separately. The preconditioners are tested on a typical problem, a Neumann boundary control for an elliptic equation. In many important situations the preconditioners substantially reduce the number of iterations needed by the solvers. In some cases, it can even be shown that the number of iterations for the preconditioned system is independent of the refinement of the discretization of the partial differential equation. System requirements: PC, World Wide Web Browser and PDF reader. Available electronically via Internet. preconditioning optimal control quadratic programming karush-kuhn-tucker systems indefinite systems Virginia Tech Mathematics John A. Burns Christopher Beattie Matthias Heinkenschloss Committee Chair unrestricted http://scholar.lib.vt.edu/theses/available/etd-12164379662151/ " s1997 vau| sm 00| 0|eng d" (VPI) etd-4437152139711101 Zabaronick, Noel A. EYE TRACKING USING FIBER OPTICS AND COMPUTER VISION TECHNIQUES Computer data - 2 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 1997 Thesis (MS)--Virginia Polytechnic Institute and State University, 1997-04-04 Includes bibliographical references. We describe a system for tracking the motion and determining the velocity of the human eye using a combination of fiber optics and imaging optics integrated with a CCD camera, a framegrabber, and a PC. Systems such as the one we describe are needed for monitoring location of interest for better human- computer interfaces and virtual reality simulations, for monitoring pilot cognitive skills during flight simulations, and for detecting the early warning signs of driver drowsiness. Where some eye-tracking devices are cumbersome because they require a person to limit head motion to remain in view of a camera or uncomfortable because they require the use of an elaborate headpiece, our proposed system is as simple to wear as a pair of eyeglasses, with the only added weight to the glasses being that of a fiber optic bundle. This fiber bundle guides the image of an 880 nm LED illuminated eye as it is reflected from a hot mirror built into the eyeglass assembly. The guided image is focused onto a CCD and the camera's output is linked to a PC framegrabber card. Software written in Microsoft Visual C++ locates the user's pupil in each video image and tracks the motion and velocity of the pupil over time. The prototype system tracks the center of the pupil to an accuracy of only 1/5 of the pupil size. This diminished accuracy results from the minimized computation scheme of pupil detection. The technique relies on edge detection and direction of image gradient over very few pixels so that the system is optimized for speed. Many other methods of pupil detection could be investigated in future research in order to optimize such a system for other parameters. System requirements: PC, World Wide Web Browser and PDF reader. Available electronically via Internet. none Virginia Tech Electrical and Computer Engineering Dr. Anbo Wang Committee Member Dr. Marten DeVries Committee Member Dr. Lynn Abbott Committee Member Dr. Richard O. Claus Committee Chair unrestricted http://scholar.lib.vt.edu/theses/available/etd-4437152139711101/ " s1997 vau| sm 00| 0|eng d" (VPI) etd-1123161739741061 Benning, Jennifer Lyn Development of Alternative Crab Claw Processing Systems to Minimize Environmental Impact Computer data - 3 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 1997 Thesis (MS)--Virginia Polytechnic Institute and State University, 1997-03-14 Includes bibliographical references. Development of Alternative Crab Claw Processing Systems to Minimize Environmental Impact by Jennifer Lyn Benning Chair: Dr. Gregory Boardman Environemental Engineering (ABSTRACT) In the recent years, environmental regulations enforced by federal, state, and local agencies have increasingly addressed water quality issues through progressively more stringent regulations. These regulations have raised concerns in the blue crab industry because processors are now subject to regulations under which new processors are unable to meet the effluent limitations with current processing techniques. This study focuses on the mechanized processing of crab claws. Currently, processors use a brine bath, referred to as the Harris Claw machine, to separate crab claw meat and shell, and this process yields a wastewater which is significantly high in pollutant strength, and is untreatable by biological methods due to the toxicity associated with the high chloride concentrations found in the waste stream. Several alternative crab claw processing systems were developed and evaluated in terms of the meat product yield, the meat product quality, and the wastewater characterization. Two alternatives involved the use of dense media, a 22.5% Staley 1300 corn syrup solution with 5.0% salt and a 30.0% Staley 1300 corn syrup solution, to separate the crab claw meat and shell. These methods, in full scale tests, produced meat yields comparable to that of the brine solution and improved the overall taste of the meat product. However, the effluents had significantly higher BOD5 concentrations. Another alternative to the Harris Claw machine, involved the design, characterization, and testing of a hydraulic separator system (HSS). The HSS was tested on a small scale, but was found to have a meat yield comparable to the Harris Claw machine. The HSS significantly improved the flavor of a final meat product, although the HSS meat product had a significantly lower shelf life than the Harris Claw machine meat product. The wastewater quality was improved, because the HSS eliminates the problems associated with a high chloride ion concentration and potentially reduces overall water consumption. System requirements: PC, World Wide Web Browser and PDF reader. Available electronically via Internet. waste minimization enviromental impact crab claw blue crab processing Virginia Tech Environmental Engineering Dr. Gregory D. Boardman Committee Chair Dr. John C. Little Dr. George J. Flick unrestricted http://scholar.lib.vt.edu/theses/available/etd-1123161739741061/ " s1997 vau| sm 00| 0|eng d" (VPI) etd-5852152749721461 Berkelman, James Habitat Requirements and Foraging Ecology of the Madagascar Fish-Eagle Computer data - 1 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 1997 Thesis (PHD)--Virginia Polytechnic Institute and State University, 1997-05-06 Includes bibliographical references. With a population estimate of 99 pairs, the Madagascar fish-eagle (Haliaeetus vociferoides) is one of the rarest birds of prey in the world. I investigated the ecological requirements of the Madagascar fish-eagle in 1994 and 1995 to help determine management action to prevent its extinction. I investigated fish-eagle foraging ecology in 1996 to determine its prey preference and whether fish abundance and availability affect fish-eagle foraging rates and foraging success. Madagascar fish-eagle nest and perch trees were taller, broader, had more unobstructed branches, and had a greater arc of accessibility than unused trees. Perch trees also were deciduous more often and had a narrower growth form than unused trees. Nest sites had more shoreline perch trees than unused sites. Lakes occupied by fish-eagles were deeper and clearer, and had more shoreline perch trees, more fish, a greater total fish weight, and more fish species than unoccupied lakes. I developed logistic regression models to predict the probability of Madagascar fish-eagle use based on the measured habitat variables. Nest and perch tree models included tree height. The nest site model included number of shoreline perches. Lake models included number of shoreline perches and either number of fish, total fish weight, or number of fish species. These models can be used to predict fish-eagle habitat use with > 70% accuracy. Introduced tilapia, Oreochromis spp. and Tilapia spp., made up the majority of both the gill net (66.3%) and fish-eagle catch (64.7%) in similar proportion, which suggests that the fish-eagle is an opportunistic predator. Replacement of native fish species by exotics, thus, probably has not been detrimental to the island's fish-eagle population. Male fish-eagle foraging success was positively correlated with number of fish, total fish weight, and number of fish species, which suggests that declines in the fish population could adversely affect the fish-eagle population. The results of this study indicate that Madagascar fish-eagles require bodies of water with large shoreline trees and an ample fish population. I recommend greater protection of aquatic habitats, monitoring and management of freshwater fish populations, and education of local people in sustainable tree harvesting practices. System requirements: PC, World Wide Web Browser and PDF reader. Available electronically via Internet. lake foraging nest tree madagascar fish-eagle perch tree habitat Virginia Tech Fisheries and Wildlife Sciences Brian R. Murphy department head Dean F. Stauffer John J. Ney Carola A. Haas James D. Fraser Committee Chair Richard G. Oderwald restricted http://scholar.lib.vt.edu/theses/available/etd-5852152749721461/ " s1998 vau| sm 00| 0|eng d" (VPI) etd-173510281975580 Zhang, Michael Tao Electrical, Thermal, and EMI Designs of High-Density, Low-Profile Power Supplies Computer data - 10 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 1998 Thesis (PHD)--Virginia Polytechnic Institute and State University, 1998-02-17 Includes bibliographical references. This work presents the analyses and designs of high-density, low-profile power supplies, including the electrical, thermal, and EMI aspects. Emphasis is placed on forward and flyback converters. The efficiency improvements of employing synchronous rectification are theoretically derived and experimentally verified in forward and flyback converters. The performances of synchronous rectifiers in forward converters are analyzed with regards to transformer reset and SR driven method. The effectiveness of synchronous rectification in flyback converters is evaluated in various operation modes and control schemes. The paralleling techniques utilized to realize high-density, low-profile power conversion are presented. Current sharing in transformer paralleling is addressed and evaluated in forward topology. The performance and the operation principles of one-choke and two-choke interleaved forward converters are analyzed. The thermal management of high-density power supplies in sealed enclosures is optimized using computational fluid dynamics simulations. The theoretical limit of power density due to thermal constraint is determined. In addition, the thermal-design optimization guidelines are given and verified experimentally. A systematic methodology is developed to facilitate the analysis and design of conducted EMI problems in high-density power supplies. Partial element equivalent circuit method is employed for parasitic parameter extraction. Layout and packaging are optimized to minimize conducted EMI noises. Noise predictions by Saber simulations are confirmed by experimental measurements. System requirements: PC, World Wide Web Browser and PDF reader. Available electronically via Internet. none Virginia Tech Electrical and Computer Engineering Douglas J. Nelson Dan Y. Chen Lay N. Chang Dusan Borojevic Milan M. Jovanovic Committee Co-Chair Fred C. Lee Committee Co-Chair unrestricted http://scholar.lib.vt.edu/theses/available/etd-173510281975580/ " s1997 vau| sm 00| 0|eng d" (VPI) etd-317182749721461 Fischer, Patrick Numerical Simulation of Microwave Sintering of Zinc Oxide Computer data - 1 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 1997 Thesis (MS)--Virginia Polytechnic Institute and State University, 1997-05-08 Includes bibliographical references. Experiments at the University of Maryland Plasma Physics Laboratory have discovered an unusual temperature response in the form of a "thermal wave" which begins at the center and propagates towards the surface of a zinc oxide sample, when heated in a microwave cavity without the presence of oxygen. This effect is believed to be caused by the irregular temperature dependence of the dielectric properties of zinc oxide, particularly dielectric loss. Two thermocouple probes were used to measure the temperature response in a small cylindrical sample of zinc oxide packed in powder insulation, and heated in a microwave oven. In order to determine if the unusual response is caused by the dielectric properties, this work uses a finite-difference mathematical model to simulate the experiments, both for the case of zinc oxide heated in ordinary air, as well as for the case of zinc oxide heated in nitrogen. A revised version of the model is used to determine if the thermocouple probe has any effect on the temperature of the sample. The spatial and temporal temperature distribution results from the model indicate that the thermocouple probe has a negligible effect on the results and that the "thermal wave" can be attributed to the irregular temperature dependence of the dielectric loss of the material. System requirements: PC, World Wide Web Browser and PDF reader. Available electronically via Internet. zinc oxide microwave heat transfer permittivity thermal wave Virginia Tech Mechanical Engineering Dr. J.R. Thomas Committee Chair Dr. E. P. Scott Dr. T. E. Diller unrestricted http://scholar.lib.vt.edu/theses/available/etd-317182749721461/ " s1996 vau| sm 00| 0|eng d" (VPI) etd-5741181879602301 Bhogaraju, Prabhakar V. V. A Case-Based Reasoner for Evaluating Crop Rotations in Whole-Farm Planning Computer data - 1 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 1996 Thesis (MS)--Virginia Polytechnic Institute and State University, 1996-07-31 Includes bibliographical references. I have worked on a Case-Based Reasoning (CBR) system that evaluates crop rotations for their soil erosion and risk of insect pest problems. The purpose of this system is to provide decision support for an automated whole-farm planner (CROPS). CROPS (Buick et al., 1992) generates crop rotation plans that can address some of the environmental, economic and legislative pressures facing natural resource managers. To generate and recommend a crop rotation plan CROPS requires estimates on the soil erosion risks and pesticide pollution potential of the crop rotation. In this research I have designed and prototyped a system that can assist CROPS in the process of whole-farm planning by providing information required for determining the soil erosion risks and the pesticide pollution potential of crop rotations. Inputs for the system include: a crop rotation, its tillage and residue management practices, and field conditions. Soil erosion risk is quantified using the C-value. Pest risks are likelihood of pest outbreaks that require control in a crop rotation. CBR was the chosen methodology for system implementation. In CBR, solutions to new problem situations are derived from retrieving and adapting solutions to similar problem situations experienced in the past. The system was prototyped using Esteem, a CBR development shell, and runs on a PC under the MS. Windows operating system. System requirements: PC, World Wide Web Browser and PDF reader. Available electronically via Internet. none Virginia Tech Entomology Forrest W. Ravlin David H. Vaughan Nicholas D. Stone Committee Chair unrestricted http://scholar.lib.vt.edu/theses/available/etd-5741181879602301/ " s1997 vau| sm 00| 0|eng d" (VPI) etd-38419290973280 Bittner, Ray A. Jr. Wormhole Run-Time Reconfiguration: Conceptualization and VLSI Design of a High Performance Computing System Computer data - 1 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 1997 Thesis (PHD)--Virginia Polytechnic Institute and State University, 1997-01-23 Includes bibliographical references. In the past, various approaches to the high performance numerical computing problem have been explored. Recently, researchers have begun to explore the possibilities of using Field Programmable Gate Arrays (FPGAs) to solve numerically intensive problems. FPGAs offer the possibility of customization to any given application, while not sacrificing applicability to a wide problem domain. Further, the implementation of data flow graphs directly in silicon makes FPGAs very attractive for these types of problems. Unfortunately, current FPGAs suffer from a number of inadequacies with respect to the task. They have lower transistor densities than ASIC solutions, and hence less potential computational power per unit area. Routing overhead generally makes an FPGA solution slower than an ASIC design. Bit-oriented computational units make them unnecessarily inefficient for implementing tasks that are generally word-oriented. And finally, in large volumes, FPGAs tend to be more expensive per unit due to their lower transistor density. To combat these problems, researchers are now exploiting the unique advantage that FPGAs exhibit over ASICs: reconfigurability. By customizing the FPGA to the task at hand, as the application executes, it is hoped that the cost-performance product of an FPGA system can be shown to be a better solution than a system implemented by a collection of custom ASICs. Such a system is called a Configurable Computing Machine (CCM). Many aspects of the design of the FPGAs available today hinder the exploration of this field. This thesis addresses many of these problems and presents the embodiment of those solutions in the Colt CCM. By offering word grain reconfiguration and the ability to partially reconfigure at computational element resolution, the Colt can offer higher effective utilization over traditional FPGAs. Further, the majority of the pins of the Colt can be used for both normal I/O and for chip reconfiguration. This provides higher reconfiguration bandwidth contrasted with the low percentage of pins used for reconfiguration of FPGAs. Finally, Colt uses a distributed reconfiguration mechanism called Wormhole Run-Time Reconfiguration (RTR) that allows multiple data ports to simultaneously program different sections of the chip independently. Used as the primary example of Wormhole RTR in the patent application, Colt is the first system to employ this computing paradigm. System requirements: PC, World Wide Web Browser and PDF reader. Available electronically via Internet. VLSI data flow DSP wormhole run-time reconfiguration FPGA Virginia Tech Electrical and Computer Engineering Scott F. Midkiff Nathaniel J. Davis A. Lynn Abbott Peter M. Athanas Committee Chair Calvin J. Ribbens unrestricted http://scholar.lib.vt.edu/theses/available/etd-38419290973280/ " s1997 vau| sm 00| 0|eng d" (VPI) etd-353622132974710 Zhong, Caoyuan Modeling of Airport Operations Using an Object-Oriented Approach Computer data - 3 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 1997 Thesis (PHD)--Virginia Polytechnic Institute and State University, 1997-02-04 Includes bibliographical references. This research develops an object-oriented approach to model airport ground network traffic operations. A generic modeling library is developed as a tool kit to model the basic traffic operations in the airfield using an object-oriented approach. The proposed generic modeling library for airfield operations is a collection of predefined abstract components implemented in the Java object-oriented programming language. Classes are defined and used as the basic components in a variety of airfield operation modeling, simulations, and optimizations. The generic airport modeling framework consists of a set the components that are necessary for modeling the basic activities of airfield traffic operations. By using the multi-threading techniques, components are integrated into the proposed modeling framework. Unlike traditional sequential simulation model, this framework organizes simulation activities into four major groups which are: flight schedule, aircraft movement, time, and animation. Instead of using built-in control logic, the framework adapts an open system policy which gives the flexibility to the end users to incorporate the user-preferred control logic into the end models. Another purpose in this research is to provide a future mechanism to study airfield ground traffic automated control systems with Just-In-Time forecasting and model system performance in a real-time ATC environment. The proposed generic library could be implemented into a Internet/intranet ready application which can query real time information and provide real time advice to pilots and air traffic controllers. This study is one of a few current research projects that are of using multiple threading technique to study traffic operation problems. The proposed generic library is originally implemented with C++ and, in the final stage, with Java, a truly cross-platform object-oriented language. Application written in Java can run on most of the mainstream computer operating systems without modifications. Although the proposed library is for airfield traffic control system, it could also be extended into air traffic control system as well as advanced transportation system. System requirements: PC, World Wide Web Browser and PDF reader. Available electronically via Internet. airport simulation object-oriented modeling java Virginia Tech Civil Engineering Dr. Keying Ye Dr. R. Sivanandan Dr. Richard D. Walker Dr. Donald R. Drew Dr. Antonio A. Trani Committee Chair unrestricted http://scholar.lib.vt.edu/theses/available/etd-353622132974710/ " s1997 vau| sm 00| 0|eng d" (VPI) etd-145110201974500 Blanks, Joseph E. Optimal Design of an Enclosure for a Portable Generator Computer data - 1 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 1997 Thesis (MS)--Virginia Polytechnic Institute and State University, 1997-02-07 Includes bibliographical references. A simple, effective design for enclosing portable generators to reduce the radiated noise is an idea that seems to be desired by the consumers in this market. This investigation is to determine the feasibility of producing such an enclosure for a generator. Several engineering aspects are incorporated in the design of the enclosure. The first, and probably the most paramount, are the acoustical effects of the enclosure itself. The investigation follows the theories for insertion loss of a close fitting enclosure. The thesis examines the system behavior of a close fitting enclosure that most acoustic text books ignore and how the material stiffness, density and source-to-enclosure distance affect the insertion loss and effectiveness of the enclosure. Measured and theoretical sound pressure level around the generator before and after the application of the enclosure are presented using standards described by ISO standard 1344. The second important consideration for the enclosure design involves the heat transfer characteristics. The requirements of cooling air to the generator are discussed. Also presented are some acoustic design considerations to prevent any "direct line of sight" to any of the necessary openings which will help in the overall insertion loss. The use of an optimal engineering design technique is presented, demonstrating its strengths and weakness in this application. The optimization method used for the study is the Hooke and Jeeves, or pattern search method. This method solved for the optimum material properties in approximately 30 iterations depending on the initial starting points and the desired weighting parameters. System requirements: PC, World Wide Web Browser and PDF reader. Available electronically via Internet. acoustic isolation insertion loss passive acoustical treatment close fitting enclosure optimization acoustic enclosure Virginia Tech Mechanical Engineering William R. Saunders Committee Chair Douglas J. Nelson Harry H. Robertshaw unrestricted http://scholar.lib.vt.edu/theses/available/etd-145110201974500/ " s1997 vau| sm 00| 0|eng d" (VPI) etd-1111112749721461 Bolling, John Glenn Implementation of Constrained Control Allocation Techniques Using an Aerodynamic Model of an F-15 Aircraft Computer data - 1 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 1997 Thesis (MS)--Virginia Polytechnic Institute and State University, 1997-05-21 Includes bibliographical references. Control Allocation as it pertains to aerospace vehicles, describes the way in which control surfaces on the outside of an aircraft are deflected when the pilot moves the control stick inside the cockpit. Previously, control allocation was performed by a series of cables and push rods, which connected the 3 classical control surfaces (ailerons, elevators, and rudder), to the 3 cockpit controls (longitudinal stick, lateral stick, and rudder pedals). In modern tactical aircraft however, it is not uncommon to find as many as 10 or more control surfaces which, instead of being moved by mechanical linkages, are connected together by complex electrical and/or hydraulic circuits. Because of the large number of effectors, there can no longer be a one-to-one correspondence between surface deflections on the outside of the cockpit to pilot controls on the inside. In addition, these exterior control surfaces have limits which restrict the distance that they can move as well as the speed at at which they can move. The purpose of Constrained Control Allocation is to deflect the numerous control surfaces in response to pilot commands in the most efficient combinations, while keeping in mind that they can only move so far and so fast. The implementation issues of Constrained Control Allocation techniques are discussed, and an aerodynamic model of a highly modified F-15 aircraft is used to demonstrate the various aspects of Constrained Control Allocation. This work was conducted under NASA research grant NAG-1-1449 supervised by John Foster of the NASA Langley Research Center System requirements: PC, World Wide Web Browser and PDF reader. Available electronically via Internet. flight control control allocation F-15 Virginia Tech Aerospace and Ocean Engineering Dr. Frederick Lutze Dr. Mark Anderson Dr. Wayne Durham Committee Chair unrestricted http://scholar.lib.vt.edu/theses/available/etd-1111112749721461/ " s1996 vau| sm 00| 0|eng d" (VPI) etd-17616979652211 Feldman, Michael A. Efficient Low-Speed Flight in a Wind Field Computer data - 1 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 1996 Thesis (MS)--Virginia Polytechnic Institute and State University, 1996-07-24 Includes bibliographical references. A new software tool was needed for flight planning of a high altitude, low speed unmanned aerial vehicle which would be flying in winds close to the actual airspeed of the vehicle. An energy modeled NLP formulation was used to obtain results for a variety of missions and wind profiles. The energy constraint derived included terms due to the wind field and the performance index was a weighted combination of the amount of fuel used and the final time. With no emphasis on time and with no winds the vehicle was found to fly at maximum lift to drag velocity, Vmd. When flying in tail winds the velocity was less than Vmd, while flying in head winds the velocity was higher than Vmd. A family of solutions was found with varying times of flight and varying fuel amounts consumed which will aid the operator in choosing a flight plan depending on a desired landing time. At certain parts of the flight, the turning terms in the energy constraint equation were found to be significant. An analysis of a simpler vertical plane cruise optimal control problem was used to explain some of the characteristics of the vertical plane NLP results. System requirements: PC, World Wide Web Browser and PDF reader. Available electronically via Internet. optimization optimal control aircraft performance Virginia Tech Aerospace and Ocean Engineering Eugene M. Cliff Committee Chair Frederick H. Lutze Wayne C. Durham unrestricted http://scholar.lib.vt.edu/theses/available/etd-17616979652211/ " s1997 vau| sm 00| 0|eng d" (VPI) etd-2720162749721461 Zhu, Ping SPACE DESIGN FOR THE ACITC EDUCATIONAL TECHNOLOGY OFFICE AREA USING A WORKPLACE NEIGHBORHOOD CONCEPT Computer data - 9 file(s) Blacksburg, Va. University Libraries, Virginia Polytechnic Institue and State University, 1997 Thesis (MS)--Virginia Polytechnic Institute and State University, 1997-04-25 Includes bibliographical references. Today, the workplace is undergoing dramatic changes, featuring increased team activities and informal interactions. The work place neighborhood is a design concept derived from a city planning theory that may solve the wor