02708ntm  2200205uu 4500008004100000035003100041100002600072245013200098256003000230260010300260502008200363504004100445520147200486538006801958538004302026653013102069710002802200720019002228856008402418      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-33451319397610811 aWalker, Gordon James 00aConceptual Development and Empirical Testing of an Outdoor Recreation Experience Model: The Recreation Experience Matrix (REM)   aComputer data - 5 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (PHD)--Virginia Polytechnic Institute and State University, 1997-03-31  aIncludes bibliographical references.3 a     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.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  aoutdoor recreation arecreation experience preference scales arecreation experience matrix arecreation opportunity spectrum 2 aVirginia TechbForestry1 aDaniel R. WilliamseCommittee MemberaK. Jill KiecolteCommittee MemberaBradley R. HerteleCommittee MemberaJoseph W. RoggenbuckeCommittee Co-ChairaR. Bruce HulleCommittee Co-Chair40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-3345131939761081/ 03917ntm  2200205uu 4500008004100000035003000041100002500071245010300096256003100199260010300230502008200333504004100415520287800456538006803334538004303402653004603445710003503491720010203526856008303628      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-1711102829758601 aA'Hearn, Francis W. 00aThe Industrial College of the Armed Forces: Contextual Analysis of an Evolving Mission, 1924-1994   aComputer data - 10 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (PHD)--Virginia Polytechnic Institute and State University, 1997-04-21  aIncludes bibliographical references.3 a     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.   aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  aHistory aAdult Education aArmed Forces 2 aVirginia TechbAdult Education1 aJohn BokelaHarold StubblefieldeCommittee ChairaMarcie BoucouvalasaThomas HuntaAlbert Wiswell40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-171110282975860/ 02319ntm  2200205uu 4500008004100000035003200041100002300073245008100096256003000177260010300207502008100310504004100391520129100432538006801723538004301791653005601834710002901890720011101919856008302030      s2000    vau|    sm    00| 0|eng d  a(VPI) etd-05012000-140300541 aBell, Tannisha D. 00aAn Examination of Race and Recurrent Substance Problems in the United States  aComputer data - 1 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c2000  aThesis (MS)--Virginia Polytechnic Institute and State University, 2000-04-17  aIncludes bibliographical references.3 a	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.     aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  aAfrican-Americans aDrugs aSubstance Abuse aRace 2 aVirginia TechbSociology1 aClifton BryanteCommittee MemberaDonald ShoemakereCommittee Co-ChairaMichael HugheseCommittee Co-Chair40zrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-05012000-14030054/ 02095ntm  2200205uu 4500008004100000035003100041100002500072245005900097256003000156260010300186502008200289504004100371520112000412538006801532538004301600653004701643710002701690720008801717856008401805      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-36211121397111011 aAhmad, Syed Alwi B. 00aFermion Quantum Field Theory In Black-hole Spacetimes   aComputer data - 1 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (PHD)--Virginia Polytechnic Institute and State University, 1997-04-18  aIncludes bibliographical references.3 aThe 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.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  aGeneral Relativity aQuantum Field Theory 2 aVirginia TechbPhysics1 aLay Nam ChangeCommittee ChairaM. BlecheraT. MizutaniaB.K. DennisonaT. Takeuchi40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-3621112139711101/ 02126ntm  2200205uu 4500008004100000035003000041100002600071245006300097256003000160260010300190502008100293504004100374520119000415538006801605538004301673653001001716710003701726720007401763856008301837      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-1334220397010911 aAnderson, Alaric Lee 00aInvestigation of Steel Joist Supported Wood Floor Systems   aComputer data - 6 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (MS)--Virginia Polytechnic Institute and State University, 1997-02-01  aIncludes bibliographical references.3 aThis 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.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  anone 2 aVirginia TechbCivil Engineering1 aT. M. MurrayeCommittee ChairaR. H. PlauteNoneaT. E. CousinseNone40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-133422039701091/ 04886ntm  2200205uu 4500008004100000035002900041100002100070245012300091256003000214260010300244502008200347504004100429520373100470538006804201538004304269653009604312710006504408720012504473856008204598      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-232815339749201 aAckley, John A. 00aWeed Management Programs in Potato, Transplanted Tomato and Transplanted Pepper with Rimsulfuron and Other Herbicides   aComputer data - 1 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (PHD)--Virginia Polytechnic Institute and State University, 1997-03-31  aIncludes bibliographical references.3 aWeed 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.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  aclomazone ametribuzin atrifluralin apepper apotato arimsulfuron anightshade atomato 2 aVirginia TechbPlant Pathology, Physiology, and Weed Science1 aHenry P. WilsoneCommittee ChairaE. Scott HagoodeNoneaJohn HesseNoneaKriton K. HatzioseNoneaRonald D. MorseeNone40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-23281533974920/ 03694ntm  2200205uu 4500008004100000035003000041100002000071245002500091256003000116260010300146502008100249504004100330520283000371538006803201538004303269653001003312710003203322720005103354856008303405      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-1233222829758601 aAdams, Nicole  00aAn Ongoing Dialogue   aComputer data - 1 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (MA)--Virginia Polytechnic Institute and State University, 1997-02-03  aIncludes bibliographical references.3 aThis 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. ³Which is the origin of the other?² is not as pertinent a question as ³how do the two inform each other?². 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 architect¹s 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 ³We 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 form² (Zambonini, 21). This quality of design can best be achieved the earlier making and materiality are involved in the design process. The questions of ³what is the form of this idea?² and ³how is this form to be made?² 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:³how can this form not only embody an idea but be the idea?², the dialogue takes on a greater import. The way in which a thing will be experienced starts to inform its making. ³It is the process that will engage both user and observer in an active, participating relationship with the work and thereby give the work its meaning² (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.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  anone 2 aVirginia TechbArchitecture1 aWilliam BrownaV. Hunter PittmanaFrank Weiner40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-123322282975860/ 04159ntm  2200205uu 4500008004100000035003000041100003100071245012700102256003000229260010300259502008200362504004100444520308000485538006803565538004303633653006303676710003103739720010203770856008103872      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-2553142029747801 aAl-Yakoob, Salem Mohammed 00aMixed-Integer Mathematical Programming Optimization Models and Algorithms For An Oil Tanker Routing and Scheduling Problem  aComputer data - 1 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (PHD)--Virginia Polytechnic Institute and State University, 1997-02-27  aIncludes bibliographical references.3 a     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   aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  aship scheduling aaggregation amixed-integer programming 2 aVirginia TechbMathematics1 aH. SheralieCommittee ChairaT. HerdmaneNoneaR. WheelereNoneaJ. BurnseNoneaL. JohnsoneNone40zrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-255314202974780/ 02077ntm  2200205uu 4500008004100000035003000041100002600071245009800097256003000195260010300225502008200328504004100410520105300451538006801504538004301572653001001615710003101625720013201656856008301788      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-3357133129718901 aAppel, Justin Ronald 00aSensitivity Calculations For Conservation Laws With Application To Discontinuous Fluid Flows   aComputer data - 1 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (PHD)--Virginia Polytechnic Institute and State University, 1997-03-14  aIncludes bibliographical references.3 a     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.   aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  anone 2 aVirginia TechbMathematics1 aMax D. GunzburgereCommittee ChairaJohn A. BurnseNoneaEugene M. CliffeNoneaTerry L. HerdmaneNoneaJanet S. PetersoneNone40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-335713312971890/ 02551ntm  2200205uu 4500008004100000035003000041100002400071245005700095256003000152260010300182502008100285504004100366520148600407538006801893538004301961653007402004710005502078720012902133856008302262      s1996    vau|    sm    00| 0|eng d  a(VPI) etd-1047223696318411 aAliftiras, George  00aReceiver Implementations for a CDMA Cellular System   aComputer data - 2 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1996  aThesis (MS)--Virginia Polytechnic Institute and State University, 1996-07-01  aIncludes bibliographical references.3 a     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.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  amultiuser receiver aCDMA ainterference cancellation aquantization 2 aVirginia TechbElectrical and Computer Engineering1 aDr. Brian D. WoernereCommittee ChairaDr. Theodore S. RappaporteCommittee MemberaDr. Charles W. BostianeCommittee Member40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-104722369631841/ 03901ntm  2200205uu 4500008004100000035003000041100002200071245009800093256003000191260010300221502008200324504004100406520286500447538006803312538004303380653004103423710003303464720011503497856008303612      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-8311023397311211 aBethard, Greg L. 00aA Microcomputer Simulation to Evaluate Management Strategies For Rearing Dairy Replacements.   aComputer data - 1 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (PHD)--Virginia Polytechnic Institute and State University, 1997-04-18  aIncludes bibliographical references.3 a     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 heifer¹s 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.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  adairy asimulation amodel aheifer 2 aVirginia TechbDairy Science1 aCarl E. PolanaThomas L. BaileyaRobert E. JameseCommittee ChairaCharles C. StallingsaMichael L. McGilliard40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-831102339731121/ 02618ntm  2200205uu 4500008004100000035003000041100002100071245009400092256003100186260010300217502008100320504004100401520155900442538006802001538004302069653006902112710003702181720011102218856008302329      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-4540164497012311 aAllan, James P. 00aThe British Labour Party in Opposition, 1979-1997: Structures, Agency, and Party  Change   aComputer data - 10 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (MA)--Virginia Polytechnic Institute and State University, 1997-04-24  aIncludes bibliographical references.3 a     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.   aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  aelectoral performance aThe Labour Party astructure and agency 2 aVirginia TechbPolitical Science1 aCharles L. TayloreCommittee ChairaStephen K. WhiteeCommittee MemberaRebecca H. DaviseCommittee Member40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-454016449701231/ 02437ntm  2200205uu 4500008004100000035003100041100002600072245010300098256003000201260010300231502008100334504004100415520138600456538006801842538004301910653005401953710005502007720008502062856008402147      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-30341129397211811 aBarake, Taha Mohamed 00aA Generalized Analysis of Multiple-Clad Fibers with Arbitrary Step-Indx Profiles and Applications   aComputer data - 1 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (MS)--Virginia Polytechnic Institute and State University, 1997-04-22  aIncludes bibliographical references.3 a     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.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  amultiple-clad fibers adispersion-altered fibers 2 aVirginia TechbElectrical and Computer Engineering1 aDr. Lee JohnsonaDr. Ioannis M. BesieresaDr. Ahmad Saffai-JazieCommittee Chair40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-3034112939721181/ 03689ntm  2200205uu 4500008004100000035003000041100003000071245006200101256003000163260010300193502008200296504004100378520238100419538006802800538004302868653013602911710005503047720029803102856008303400      s1996    vau|    sm    00| 0|eng d  a(VPI) etd-5220145896424811 aAlmajdoub, Salahuddin A. 00aA Design Methodology for Physical Design for Testability   aComputer data - 2 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1996  aThesis (PHD)--Virginia Polytechnic Institute and State University, 1996-07-01  aIncludes bibliographical references.3 a     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.   aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  aBridging Faults aThe Labour Party aStructure and Agency aIDDQ Testing aElectoral Performance aPhysical Design for Testability 2 aVirginia TechbElectrical and Computer Engineering1 aCharles L. TayloreCommittee ChairaRebecca H. DaviseCommittee MemberaStephen K. WhiteeCommittee MemberaScott F. MidkiffeCommittee ChairaJames R. ArmstrongeCommittee MemberaHanif D. SheralieCommittee MemberaAicha A. Elshabini-RiadeCommittee MemberaJoseph G. TronteCommittee Member40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-522014589642481/ 02937ntm  2200205uu 4500008004100000035003000041100002200071245004200093256003000135260010300165502008200268504004100350520192700391538006802318538004302386653005702429710005302486720010902539856008302648      s1996    vau|    sm    00| 0|eng d  a(VPI) etd-2742103596115411 aAtalla, Mauro J. 00aModel Updating Using Neural Networks   aComputer data - 1 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1996  aThesis (PHD)--Virginia Polytechnic Institute and State University, 1996-04-01  aIncludes bibliographical references.3 a     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.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  aadaptive control aneural networks amodel updating 2 aVirginia TechbEngineering Science and Mechanics1 aDaniel J. InmaneCommittee ChairaHarry H. RobertshawaAli H. NayfehaRonald D. KrizaO. H. Griffin, Jr.40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-274210359611541/ 01786ntm  2200205uu 4500008004100000035003100041100002100072245007400093256003000167260010300197502008100300504004100381520081700422538006801239538004301307653004101350710003101391720007401422856008401496      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-32101920497213911 aBail, Thomas R. 00aA Disturbance-Rejection Problem for a 2-D Airfoil Exhibiting Flutter   aComputer data - 1 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (MS)--Virginia Polytechnic Institute and State University, 1997-04-21  aIncludes bibliographical references.3 a     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.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  aLQG aH aflutter asingular values 2 aVirginia TechbMathematics1 aDr. Terry HerdmanaDr. Robert RogersaDr. John BurnseCommittee Chair40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-3210192049721391/ 02453ntm  2200205uu 4500008004100000035003100041100002200072245007500094256003000169260010300199502008100302504004100383520143500424538006801859538004301927653006601970710005502036720007202091856008402163      s1996    vau|    sm    00| 0|eng d  a(VPI) etd-05213181096132201 aFleming, Todd B. 00aImproving the Performance of the world Wide Web over Wireless Networks  aComputer data - 1 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1996  aThesis (MS)--Virginia Polytechnic Institute and State University, 1996-11-04  aIncludes bibliographical references.3 a     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.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  awireless networks aWWW aMHSP aproxy athreads aprotocols 2 aVirginia TechbElectrical and Computer Engineering1 aScott F. MidkiffeCommittee ChairaNathaniel J. DavisaF. Gail Gray40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-0521318109613220/ 02616ntm  2200205uu 4500008004100000035003000041100002600071245009300097256003000190260010300220502008100323504004100404520163300445538006802078538004302146653001002189710003602199720009202235856008302327      s1996    vau|    sm    00| 0|eng d  a(VPI) etd-3101412596316311 aBatongbacal, Alan L. 00aA User-Extensible Architecture for Visualization and Analysis of Time-Series Trace Data   aComputer data - 1 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1996  aThesis (MS)--Virginia Polytechnic Institute and State University, 1996-04-01  aIncludes bibliographical references.3 a     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.   aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  anone 2 aVirginia TechbComputer Science1 aProf. Marc AbramseCommittee ChairaProf. Dennis KafuraeNoneaProf. Sallie HenryeNone40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-310141259631631/ 03773ntm  2200205uu 4500008004100000035002900041100002500070245008900095256003000184260010300214502008100317504004100398520271000439538006803149538004303217653011303260710003103373720008103404856008203485      s1996    vau|    sm    00| 0|eng d  a(VPI) etd-121643796621511 aBattermann, Astrid  00aPreconditioning of Karush--Kuhn--Tucker Systems arising in Optimal Control Problems   aComputer data - 1 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1996  aThesis (MS)--Virginia Polytechnic Institute and State University, 1996-06-14  aIncludes bibliographical references.3 a     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.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  apreconditioning aoptimal control aquadratic programming akarush-kuhn-tucker systems aindefinite systems 2 aVirginia TechbMathematics1 aJohn A. BurnsaChristopher BeattieaMatthias HeinkenschlosseCommittee Chair40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-12164379662151/ 02873ntm  2200205uu 4500008004100000035003100041100002500072245006800097256003000165260010300195502008100298504004100379520183900420538006802259538004302327653001002370710005502380720014802435856008402583      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-44371521397111011 aZabaronick, Noel A. 00aEYE TRACKING USING FIBER OPTICS AND COMPUTER VISION TECHNIQUES   aComputer data - 2 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (MS)--Virginia Polytechnic Institute and State University, 1997-04-04  aIncludes bibliographical references.3 a     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.   aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  anone 2 aVirginia TechbElectrical and Computer Engineering1 aDr. Anbo WangeCommittee MemberaDr. Marten DeVrieseCommittee MemberaDr. Lynn AbbotteCommittee MemberaDr. Richard O. ClauseCommittee Chair40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-4437152139711101/ 03476ntm  2200205uu 4500008004100000035003100041100002700072245009400099256003000193260010300223502008100326504004100407520241500448538006802863538004302931653008102974710004503055720008603100856008403186      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-11231617397410611 aBenning, Jennifer Lyn 00aDevelopment of Alternative Crab Claw Processing Systems to Minimize Environmental Impact   aComputer data - 3 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (MS)--Virginia Polytechnic Institute and State University, 1997-03-14  aIncludes bibliographical references.3 a     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.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  awaste minimization aenviromental impact acrab claw ablue crab processing 2 aVirginia TechbEnvironmental Engineering1 aDr. Gregory D. BoardmaneCommittee ChairaDr. John C. LittleaDr. George J. Flick40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-1123161739741061/ 03677ntm  2200205uu 4500008004100000035003100041100002300072245007700095256003000172260010300202502008200305504004100387520258000428538006803008538004303076653008003119710005103199720013903250856008203389      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-58521527497214611 aBerkelman, James  00aHabitat Requirements and Foraging Ecology of the Madagascar Fish-Eagle    aComputer data - 1 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (PHD)--Virginia Polytechnic Institute and State University, 1997-05-06  aIncludes bibliographical references.3 a     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.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  alake aforaging anest tree amadagascar fish-eagle aperch tree ahabitat 2 aVirginia TechbFisheries and Wildlife Sciences1 aBrian R. Murphyedepartment headaDean F. StaufferaJohn J. NeyaCarola A. HaasaJames D. FrasereCommittee ChairaRichard G. Oderwald40zrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-5852152749721461/ 02815ntm  2200205uu 4500008004100000035003000041100002400071245008500095256003100180260010300211502008200314504004100396520177400437538006802211538004302279653001002322710005502332720013902387856008302526      s1998    vau|    sm    00| 0|eng d  a(VPI) etd-1735102819755801 aZhang, Michael Tao 00aElectrical, Thermal, and EMI Designs of High-Density, Low-Profile Power Supplies  aComputer data - 10 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1998  aThesis (PHD)--Virginia Polytechnic Institute and State University, 1998-02-17  aIncludes bibliographical references.3 a	  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.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  anone 2 aVirginia TechbElectrical and Computer Engineering1 aDouglas J. NelsonaDan Y. ChenaLay N. ChangaDusan BorojevicaMilan M. JovanoviceCommittee Co-ChairaFred C. LeeeCommittee Co-Chair40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-173510281975580/ 02316ntm  2200205uu 4500008004100000035003000041100002300071245006200094256003000156260010300186502008100289504004100370520131700411538006801728538004301796653007401839710004201913720007201955856008302027      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-3171827497214611 aFischer, Patrick  00aNumerical Simulation of Microwave Sintering of Zinc Oxide  aComputer data - 1 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (MS)--Virginia Polytechnic Institute and State University, 1997-05-08  aIncludes bibliographical references.3 aExperiments 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.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  azinc oxide amicrowave aheat transfer apermittivity athermal wave 2 aVirginia TechbMechanical Engineering1 aDr. J.R. ThomaseCommittee ChairaDr. E. P. ScottaDr. T. E. Diller40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-317182749721461/ 02520ntm  2200205uu 4500008004100000035003100041100003200072245007900104256003000183260010300213502008100316504004100397520156500438538006802003538004302071653001002114710003002124720007602154856008402230      s1996    vau|    sm    00| 0|eng d  a(VPI) etd-57411818796023011 aBhogaraju, Prabhakar V. V. 00aA Case-Based Reasoner for Evaluating Crop Rotations in Whole-Farm Planning  aComputer data - 1 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1996  aThesis (MS)--Virginia Polytechnic Institute and State University, 1996-07-31  aIncludes bibliographical references.3 a      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.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  anone 2 aVirginia TechbEntomology1 aForrest W. RavlinaDavid H. VaughanaNicholas D. StoneeCommittee Chair40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-5741181879602301/ 03819ntm  2200205uu 4500008004100000035002900041100002400070245011200094256003000206260010300236502008200339504004100421520272100462538006803183538004303251653007103294710005503365720011103420856008203531      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-384192909732801 aBittner, Ray A. Jr.00aWormhole Run-Time Reconfiguration: Conceptualization and VLSI Design of a High Performance Computing System  aComputer data - 1 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (PHD)--Virginia Polytechnic Institute and State University, 1997-01-23  aIncludes bibliographical references.3 a     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.         aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  aVLSI adata flow aDSP awormhole run-time reconfiguration aFPGA 2 aVirginia TechbElectrical and Computer Engineering1 aScott F. MidkiffaNathaniel J. DavisaA. Lynn AbbottaPeter M. AthanaseCommittee ChairaCalvin J. Ribbens40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-38419290973280/ 03474ntm  2200205uu 4500008004100000035003000041100002100071245006900092256003000161260010300191502008200294504004100376520244100417538006802858538004302926653006002969710003703029720011903066856008303185      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-3536221329747101 aZhong, Caoyuan  00aModeling of Airport Operations Using an Object-Oriented Approach  aComputer data - 3 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (PHD)--Virginia Polytechnic Institute and State University, 1997-02-04  aIncludes bibliographical references.3 a     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.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  aairport asimulation aobject-oriented modeling ajava 2 aVirginia TechbCivil Engineering1 aDr. Keying YeaDr. R. SivanandanaDr. Richard D. WalkeraDr. Donald R. DrewaDr. Antonio A. TranieCommittee Chair40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-353622132974710/ 02919ntm  2200205uu 4500008004100000035003000041100002300071245006100094256003000155260010300185502008100288504004100369520185200410538006802262538004302330653013402373710004202507720008102549856008302630      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-1451102019745001 aBlanks, Joseph E. 00aOptimal Design of an Enclosure for a Portable Generator   aComputer data - 1 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (MS)--Virginia Polytechnic Institute and State University, 1997-02-07  aIncludes bibliographical references.3 a     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.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  aacoustic isolation ainsertion loss apassive acoustical treatment aclose fitting enclosure aoptimization aacoustic enclosure 2 aVirginia TechbMechanical Engineering1 aWilliam R. SaunderseCommittee ChairaDouglas J. NelsonaHarry H. Robertshaw40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-145110201974500/ 02633ntm  2200205uu 4500008004100000035003100041100002500072245011100097256003000208260010300238502008100341504004100422520159200463538006802055538004302123653004802166710005102214720007802265856008402343      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-11111127497214611 aBolling, John Glenn 00aImplementation of Constrained Control Allocation Techniques Using an Aerodynamic Model of an F-15 Aircraft  aComputer data - 1 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (MS)--Virginia Polytechnic Institute and State University, 1997-05-21  aIncludes bibliographical references.3 aControl 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    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  aflight control acontrol allocation aF-15 2 aVirginia TechbAerospace and Ocean Engineering1 aDr. Frederick LutzeaDr. Mark AndersonaDr. Wayne DurhameCommittee Chair40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-1111112749721461/ 02249ntm  2200205uu 4500008004100000035002900041100002500070245004700095256003000142260010300172502008100275504004100356520126900397538006801666538004301734653005901777710005101836720007401887856008201961      s1996    vau|    sm    00| 0|eng d  a(VPI) etd-176169796522111 aFeldman, Michael A. 00aEfficient Low-Speed Flight in a Wind Field  aComputer data - 1 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1996  aThesis (MS)--Virginia Polytechnic Institute and State University, 1996-07-24  aIncludes bibliographical references.3 aA 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.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  aoptimization aoptimal control aaircraft performance 2 aVirginia TechbAerospace and Ocean Engineering1 aEugene M. CliffeCommittee ChairaFrederick H. LutzeaWayne C. Durham40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-17616979652211/ 02907ntm  2200205uu 4500008004100000035003100041100001600072245010600088256003000194260010300224502008100327504004100408520186800449538006802317538004302385653004702428710006802475720007602543856008202619      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-27201627497214611 aZhu, Ping  00aSPACE DESIGN FOR THE ACITC EDUCATIONAL TECHNOLOGY OFFICE AREA USING A WORKPLACE NEIGHBORHOOD CONCEPT   aComputer data - 9 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (MS)--Virginia Polytechnic Institute and State University, 1997-04-25  aIncludes bibliographical references.3 a     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      workplace design problems arising from these      changes, and provided a focus for this project.      The Educational Technology office area of      the Advanced Communication and      Information Technology Center (ACITC)      possesses the features representing the general      workplace tendency today. The purpose of      this project was to develop a workplace      neighborhood space prototype for this office      area. This prototype will provide a work      environment conducive to team efforts and      informal interactions and a workplace      neighborhood space model for future      reference.       The project had three design phases: design      programming, design development, and      design evaluation and revision. During the      design programming, a survey questionnaire      was distributed to all of the 12 Educational      Technology employees and behavioral      mapping observations were conducted. Then,      a conceptual plan, a series of workplace space      patterns and a floor plan were developed for      the workplace neighborhood space prototype.      Finally, computer models were prepared for      three neighborhood units for design      evaluation.       The result of the design evaluation indicated      that the concerns between individual and      group work spaces were not solved. The space      prototype was revised, and a computer model      of the revised space prototype was prepared.      The revised space prototype met the work      patterns of the employees more closely and      reflected the design concept of workplace      neighborhood more clearly   aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  aspace adesign aworkplace aneighborhood 2 aVirginia TechbHousing, Interior Design and Resource Management1 aEric WiedegreenaLennie Scott-WebberaJoan McLain-KarkeCommittee Chair40zrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-2720162749721461/ 04118ntm  2200205uu 4500008004100000035002900041100002200070245007200092256003100164260010300195502008200298504004100380520303900421538006803460538004303528653009003571710005003661720011903711856008203830      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-184412139729001 aYagow, Eugene R. 00aAuxiliary Procedures for the AGNPS Model in Urban Fringe Watersheds  aComputer data - 10 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (PHD)--Virginia Polytechnic Institute and State University, 1997-02-28  aIncludes bibliographical references.3 aThe Agricultural Nonpoint Source model (AGNPS) is a single-event grid-based model used for simulating runoff, sediment and nutrients from agricultural areas. This study involved using geographic information system (GIS) spatial data and functionality to improve the spatial and temporal assignment of parameter values for the AGNPS 5.0 model and incorporated methods for representing urban fringe land uses and their nonpoint source (NPS) pollution contributions in model inputs. Auxiliary procedures for modeling with AGNPS were developed both for enhancing input into the model and for enhancing modeled output. On an event basis, one procedure automated the creation of complex-formatted AGNPS 5.0 model input files using GIS as a spatial data manager. One pair of alternative procedures were developed to automate the assignment of parameter values on an event basis. One procedure used typical average annual parameter values, and the second assigned parameter values using adaptations of existing time-dependent relationships. On a monthly basis, a sequencing procedure was created to perform multiple runs with the model for a list of storms while updating parameters for each event and aggregating monthly modeled spatial output. Another pair of alternative procedures were developed to facilitate the simulation of monthly output from AGNPS modeled events. The first of these aggregated event output for all storms in each month, while the second supplemented the aggregated output with baseflow and septic system loads. The study area was the 6,500 ha urbanizing Bull Run watershed in northern Virginia, which was modeled as 14,621 cells. Databases were assembled and 109 selected storm events within a 16-year period were modeled using the above procedures. Event data were added together, where necessary, to correspond with observed data from composite-sampled intervals. Output from the two event parameterization procedures were compared with monitored loads calculated for 89 composite periods, while output from the two monthly simulation procedures were compared with monthly monitored data for 23 complete months. The monitored-modeled comparisons were considered inconclusive. Evidence strongly suggested that the rainfall records from a rain gauge outside the watershed did not correspond well with monitored runoff. The average runoff produced with the AGNPS model from the 109 selected storms amounted to 40.7% of rainfall, consistent with the calculated long-term average of 38% for the Bull Run watershed. A nonpoint source pollution index was developed to utilize monthly modeled total nitrogen, total phosphorus, and suspended sediment. Individual rating curves were developed to separately transform loads and concentrations of each pollutant into sub-index values. The maximum sub-index from each parameter was added together and averaged for the index. The index was calculated at the watershed outlet from monitored data, and in a spatially-distributed fashion along all streams from simulated output.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  ageographic information systems aindex amodel interface anonpoint source pollution 2 aVirginia TechbBiological Systems Engineering1 aMary Leigh WolfeaJohn PerumpralaSaied MostaghimiaTheo DillahaaJames BohlandaVernon ShanholtzeCommittee Chair40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-18441213972900/ 01951ntm  2200205uu 4500008004100000035003100041100002300072245014600095256003100241260010300272502008100375504004100456520091600497538006801413538004301481653001001524710002901534720009801563856008401661      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-22301024497614311 aYatsko, Michael S 00aEthnicity in Festival Landscapes: An   Analysis of the Landscape of Jaialdi  '95 as a Spatial Expression of Basque                  Ethnicity  aComputer data - 16 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (MS)--Virginia Polytechnic Institute and State University, 1997-05-08  aIncludes bibliographical references.3 aEthnic festivals are dynamic socio-spatial phenomena in American society in which rationalized spaces are transformed into “festival space” and the cultural landscapes within the boundaries of the festivals are transfigured into festival landscapes. The landscapes of ethnic festivals generate, via a colorful assortment of cultural performances and symbols, metaphors of ethnicity and spatial expressions of social processes which influence ethnic groups. As a metaphor of ethnicity, festival landscapes have become both a tool for the ethnic boundary maintenance of ethnic groups and a form of symbolic ethnicity for many assimilated individuals. This thesis analyzes the landscape of the Basque festival, Jaialdi ’95, as a tool for the ethnic boundary maintenance for the American Basque community and the Basque colony in Boise, Idaho, and as a form of symbolic ethnicity for assimilated American Basques.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  anone 2 aVirginia TechbGeography1 aNeil L. ShumskyaKristin AddisaBonham C. RichardsonaSusan R. Brooker-GrosseCommittee Chair40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-2230102449761431/ 04936ntm  2200205uu 4500008004100000035002900041100001900070245015400089256003000243260010300273502008200376504004100458520379200499538006804291538004304359653009004402710005304492720010304545856008204648      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-335016329716101 aZhou, Hongyi  00aSTRUCTURE-PROPERTY RELATIONSHIPS: MODEL STUDIES ON MELT EXTRUDED UNIAXIALLY ORIENTED HIGH DENSITY POLYETHYLENE FILMS HAVING WELL DEFINED MORPHOLOGIES  aComputer data - 1 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (PHD)--Virginia Polytechnic Institute and State University, 1997-02-14  aIncludes bibliographical references.3 aHigh density polyethylene (HDPE) films having simple and well-defined stacked lamellar morphology, either with or without a distinct presence of row-nucleated fibril structures, have been utilized as model materials to carry out investigations on solid state structure-property relationships. Four different subjects that were addressed are: 1) mechanical properties and deformation morphologies, 2) orientation anisotropy of the dynamic mechanical a relaxation, 3) orientation dependence of creep behavior, and 4) crystalline lamellar thickness and its distribution. For the first three topics, appropriate mechanical tests, including tensile (INSTRON), creep (TMA), and dynamic mechanical (DMTA) tests, were performed at different angles with respect to the original machine direction (MD) of the melt extruded films; morphological changes as a result of these mechanical tests were detected by WAXS, SAXS, and TEM. For the forth topic, crystalline lamellar thickness and its distribution were determined by DSC, SAXS, TEM and AFM experiments. In the large strain deformation study (chapter 4.0), samples were stretched at 00°, 45° and 90° angles with respect to the original MD. A distinct orientation dependence of the tensile behavior was observed and correlated to the corresponding deformation modes and morphological changes, namely 1) lamellar separation and fragmentation by chain slip for the 00° stretch, 2) lamellar break-up via chain pull-out for the 90° stretch, and 3) lamellar shear, rotation and break-up through chain slip and/or tilt for the 45° stretch. A strong strengthening effect was observed for samples with row-nucleated fibril structures at the 00° stretch; whereas for the 90° stretch, the presence of such structures significantly limited deformability of the samples. In the dynamic strain mechanical a relaxation study (chapter 5.0), samples were tested at nine different angles with respect to the original MD, and the morphologies of samples before and after the dynamic tests were also investigated. The mechanical dispersions for the 00° and 90° tests were believed to arise essentially from the crystalline phase, and they contain contributions from two earlier recognized sub-relaxations of aI and aII. While for the 45° test, in addition to a high temperature aII relaxation, a interlamellar shear induced low temperature mechanical relaxation was also observed. It is concluded that the low temperature relaxation is related to the characteristics of the interface between the crystalline lamellae and amorphous layers. In the small strain creep study (chapter 6.0), samples were tested at the 00°, 45° and 90° angles at the original MD. Both creep strain and creep rate for samples at the three angles were very different. An Eyring-rate model was utilized to analysis the observed creep behavior, and structural parameters associated with this model, including population of creep sites, activation energy and volume, were obtained by fitting the experimental data to the Eyring-rate equation. It was concluded that the plateau creep rate in these model materials is primarily controlled by the density and physical state of tie-chains in the amorphous phase. For the lamellar thickness and distribution study, DSC, SAXS, TEM and AFM experiments were conducted for samples having a well-defined stacked lamellar morphology. It was found that the most probable lamellar thickness from SAXS and TEM agreed very well; however, these values did not match with those obtained by DSC and AFM. It was pointed out that the use of DSC to determine lamellar thickness and distribution is so sensitive to heating rate and numerical values for the parameters in the Gibbs-Thomson equation that it is not believed to be suitable for quantitative analysis.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  apolyethylene atensile property amechanical relaxation acreep alamellar thickness 2 aVirginia TechbMaterials Science and Engineering1 aThomas C. WardaHerve MarandaRonald G. KanderaDavid A. DillardaGarth L. WilkeseCommittee Chair40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-33501632971610/ 02429ntm  2200205uu 4500008004100000035003000041100002200071245005700093256003000150260010300180502008100283504004100364520141400405538006801819538004301887653009001930710005302020720006702073856008302140      s1996    vau|    sm    00| 0|eng d  a(VPI) etd-5201128596517911 aWaldhart, Chris  00aAnalysis of Tow-Placed, Variable-Stiffness Laminates  aComputer data - 2 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1996  aThesis (MS)--Virginia Polytechnic Institute and State University, 1996-06-05  aIncludes bibliographical references.3 a     It is possible to create laminae that have spatially varying fiber orientation with a tow placement machine. A      laminate which is composed of such plies will have stiffness properties which vary as a function of position.      Previous work had modelled such variable-stiffness laminae by taking a reference fiber path and creating      subsequent paths by shifting the reference path. This thesis introduces a method where subsequent paths are      truly parallel to the reference fiber path. The primary manufacturing constraint considered in the analysis of      variable-stiffness laminates was limits on fiber curvature which proved to be more restrictive for parallel      fiber laminae than for shifted fiber. The in-plane responses of shifted and parallel fiber variable-stiffness      laminates to either an applied uniform end shortening or in-plane shear were determined. Both shifted and      parallel fiber variable-stiffness laminates can redistribute the applied load thereby increasing critical buckling      loads compared to traditional straight fiber laminates. The primary differences between the two methods is      that parallel fiber laminates are not able to redistribute the loading to the degree of the shifted fiber. This      significantly reduces the increase in critical buckling load for parallel fiber variable-stiffness laminates over      straight fiber laminates.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  avariable-stiffness laminates acurvilinear fibers atow placement machine abuckling 2 aVirginia TechbEngineering Science and Mechanics1 aRobert M. JonesaZafer GurdaleCommittee ChairaCalvin Ribbens40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-520112859651791/ 01881ntm  2200205uu 4500008004100000035003000041100002300071245006800094256003000162260010300192502008200295504004100377520088600418538006801304538004301372653001001415710004601425720012101471856008301592      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-3014111319744301 aWalker, Kenroy A. 00aThe Aspirations Formation of Disadvantaged Jamaican Male Youths  aComputer data - 2 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (PHD)--Virginia Polytechnic Institute and State University, 1997-01-30  aIncludes bibliographical references.3 a     This study examined the aspirations formation of disadvantaged Jamaican male youths. The design of the study      was a Type 3 holistic design which considered the global nature of multiple cases, and focused on the impact of      work, family, school, peers and siblings on subjects1 aspirations. Six case studies were conducted using      observations, focus groups, taped interviews and document inspection techniques. Data were analyzed using      McCraken1s coding techniques. The results showed that the youths1 aspirations were leveled, reflected realities      of their employment possibilities, and were patterned after their father1s occupations. The youths1 reluctance      to raise their aspirations signals the need for Jamaican policy makers to address the problems caused by low      aspirations among youths. Recommendations for further research are offered.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  anone 2 aVirginia TechbCurriculum and Instruction1 aDr. Joyce Williams-GreenaDr. Terry WildmanaDr. Jimmie FortuneaDr. John BurtonaDr. Darrel CloweseCommittee Chair40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-301411131974430/ 02888ntm  2200205uu 4500008004100000035003000041100002900071245012600100256003000226260010300256502008100359504004100440520177500481538006802256538004302324653006902367710004802436720011502484856008302599      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-0551321397111011 aWalsh, Maryann Sheridan 00aLOOKING AT THE PICTURE BY STEPPING OUTSIDE: A QUALITATIVE STUDY OF PARENTS' OF ADOLESCENTS EXPERIENCES IN FAMILY THERAPY   aComputer data - 1 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (MS)--Virginia Polytechnic Institute and State University, 1997-04-03  aIncludes bibliographical references.3 aParents with adolescents often find themselves caught in the stress and strain that normally accompanies this      stage of life. It is when parents cannot meet the demands of troubled adolescents that they find themselves      seeking family therapy. Most of what is reported about the process of therapy continues to be from the      therapist's or reseacher's perspective. There has been an increased interest in what clients have to say about      their experiences. The purpose of this study was to develop a detailed description of how parents of adolescents      who attended family therapy in private practice settings viewed their experiences. Fifteen parents who had been      to therapy with their adolescent were recruited by their therapist to be interviewed for this study. A multicase      qualitative design and constructivist theoretical framework guided the investigation. The constant comparative      analysis was used to develop four core categories that described the subtitles of parents' therapeutic experience.      Five case stories illustrated the core categories and parents' quotes were used to further embellish the findings.      The findings included parents' experiences prior to beginning therapy, during therapy as well as reflections in      retrospect. The pre-therapy presentation, based on expectations and past experiences in treatment, affected the      way parents initially approached therapy. A supportive therapeutic climate was necessary for parents to trust      and become open to possibilities and do the hard work required to make changes. The story of their current      experience was part of the family therapy process. Parents recognized changes and what they valued about their      experiences in family therapy.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  aparents of adolescents aclients experience aqualitative study 2 aVirginia TechbFamily and Child Development1 aSandra M. Stith, Ph.D.aEric E. mcCollum, Ph.D.aJean L. Coleman, Ed.DaKaren H. Rosen, Ed.D.eCommittee Chair40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-055132139711101/ 02522ntm  2200205uu 4500008004100000035003100041100002200072245006400094256003000158260010300188502008200291504004100373520148600414538006801900538004301968653006102011710003102072720012902103856008402232      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-11152023397311211 aBorisuk, Mark T. 00aBIFURCATION ANALYSIS OF A MODEL OF THE FROG EGG CELL CYCLE   aComputer data - 1 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (PHD)--Virginia Polytechnic Institute and State University, 1997-04-21  aIncludes bibliographical references.3 a     Fertilized frog eggs (and cell-free extracts)      undergo periodic oscillations in the activity of      "M-phase promoting factor" (MPF), the      crucial triggering enzyme for mitosis (nuclear      division) and cell division. MPF activity is      regulated by a complex network of      biochemical reactions. Novak and Tyson, and      their collaborators, have been studying the      qualitative and quantitative properties of a large      system of nonlinear ordinary differential      equations that describe the molecular details of      this system as currently known. Important      clues to the behavior of the model are      provided by bifurcation theory, especially      characterization of the codimension-1 and -2      bifurcation sets of the differential equations. To      illustrate this method, I have been studying a      system of 9 ordinary differentail equations that      describe the frog egg cell cycle with some      fidelity. I will describe the bifurcation diagram      of this system in a parameter space spanned by      the rate constants for cyclin synthesis and      cyclin degradation. My results suggest either      that the cell cycle control system should show      dynamical behavior considerably more      complex than the limit cycles and steady states      reported so far, or that the biochemical rate      constants of the system are constrained to      avoid regions of parameter space where      complex bifurcation points unfold.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  acell cycle aMPF abifurcation theory aparameter space 2 aVirginia TechbMathematics1 aJohn A. BurnsaJohn J. TysoneCommittee Co-ChairaTerry L. HerdmaneCommittee Co-ChairaKenneth P. HannsgenaEugene M. Cliff40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-1115202339731121/ 02771ntm  2200205uu 4500008004100000035003000041100002500071245007700096256003000173260010300203502008100306504004100387520179100428538006802219538004302287653005102330710003502381720006802416856008102484      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-5329161029716801 aBowser, Kristina L. 00aTHE EFFECTS DAILY, MAXIMAL OF RESISTANCE EXERCISE ON MUSCULAR FUNCTION    aComputer data - 4 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (MS)--Virginia Polytechnic Institute and State University, 1997-02-10  aIncludes bibliographical references.3 a     Overtraining is a common problem in athletes      that prevents many from becoming ³elite². A      decrement in an athletes¹ performance is      usually an indicator that overtraining syndrome      may be developing. Unfortunately, there is no      model that can determine overtraining. A      decline in performance results in a depression      in maximum muscular force. It is not known      whether the force depression is a result of      central or peripheral factors. In this study, the      two training protocols on different legs      determined whether force declines are      muscular (peripheral) or psychological      (central). Specifically, in this study, the      subjects trained one leg at maximal intensity      for two weeks, and the other trained at a low      intensity for two weeks. After training for two      weeks, both legs were placed on a low      intensity workout to monitor the recovery      process. The purpose of this study was to      observe muscle strength performance      decrements after overtraining one leg in      comparison to properly training the other leg      by knee extension exercises for two weeks in      trained males. Also, after overtraining the one      leg for two weeks, the leg was placed on a      reduced training program in order to look at      recovery if overtraining occurred. Maximal      force output was measured isokinetically on      the Biodex three times: pre-, post-, and final      test. An analysis of this data revealed no      significant changes in maximal muscular force      output after a high intensity training protocol.      Therefore, this investigation demonstrated that      overtraining in the quadricep did not result      from the two weeks of high intensity      resistance training.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  amuscle force aovertraining aweight training 2 aVirginia TechbHuman Nutrition1 aJay H. WilliamseCommittee ChairaKerry RedicanaShala E. Davis40zrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-532916102971680/ 02129ntm  2200205uu 4500008004100000035003100041100002500072245011200097256003000209260010300239502008100342504004100423520106700464538006801531538004301599653008401642710003701726720007601763856008401839      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-48142219497113811 aBoyd, Curtis Barton 00aA Load-Deflection Study of  Fiber-Reinforced Plastics as Reinforcement in Concrete Bridge Decks              aComputer data - 1 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (MS)--Virginia Polytechnic Institute and State University, 1997-05-05  aIncludes bibliographical references.3 aApproximately fifty percent of the bridges in the United States are considered deficient. The deterioration of the concrete components is a leading cause of the problem. The deterioration of concrete bridge decks is due primarily to corrosion of the reinforcing steel in the concrete. A promising solution to the problem is the use of fiber reinforced plastics (FRP) as a replacement for reinforcing steel. The use of FRP as reinforcement has the following advantages of lightweight, high tensile strength, corrosion resistance, flexibility, and electromagnetic resistance. This paper looks at the use of FRP as reinforcement in concrete beams and compares the information from deflection measurements of different configurations. Also, a material cost comparison is made to determine the cost of using the FRP reinforcement over standard steel reinforcement. Concrete bridge deck systems are designed using steel and fiber-reinforced plastics and allowable stress and load resistance factor methods. Recommendations for further study and uses of FRP are made.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  abridge areinforced concrete abridge design aFRP afiber reinforced plastics 2 aVirginia TechbCivil Engineering1 aRichard M. BarkereCommittee ChairaThomas M. MurrayaRichard E. Weyers40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-4814221949711381/ 03672ntm  2200205uu 4500008004100000035003000041100002200071245007800093256003000171260010300201502008200304504004100386520258300427538006803010538004303078653010003121710005303221720010903274856008303383      s1996    vau|    sm    00| 0|eng d  a(VPI) etd-3941721596517211 aWard III, Allan  00aResidual Stress Effects on Power Slump and Wafer Breakage in GaAs MESFETs  aComputer data - 2 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1996  aThesis (PHD)--Virginia Polytechnic Institute and State University, 1996-06-06  aIncludes bibliographical references.3 aThe objectives of this investigation are to develop a precise, non-destructive single crystal stress measurement      technique, develop a model to explain the phenomenon known as 3power slump2, and investigate the role of      device processing on wafer breakage. All three objectives were successfully met. The single crystal stress      technique uses a least squares analysis of X-ray diffraction data to calculate the full stress tensor. In this way,      precise non-destructive stress measurements can be made with known error bars. Rocking curve analysis,      stress gradient corrections, and a data reliability technique were implemented to ensure that the stress data are      correct. A theory was developed to explain 3power slump2, which is a rapid decrease in the amplifying      properties of microwave amplifier circuits during operation. The model explains that for the particular      geometry and bias configuration of the devices studied in this research, power slump is linearly related to      shear stress at values of less than 90 MPa. The microscopic explanation of power slump is that radiation      enhanced dislocation glide increases the kink concentration, thereby increasing the generation center      concentration in the active region of the device. These generation centers increase the total gate current,      leading to a decrease in the amplifying properties of the device. Passivation layer processing has been shown      to both reduce the fracture strength and increase the residual stress in GaAs wafers, making them more      susceptible to wafer breakage. Bare wafers are found to have higher fracture strength than passivated wafers.      Bare wafers are also found to contain less residual stress than SiON passivated wafers, which, in turn, are      found to have less stress than SiN passivated wafers. Topographic imaging suggests that SiN passivated wafers      have larger flaws than SiON passivated wafers, and that the distribution of flaw size among SiN passivated      wafers is wider than the distribution of flaws in SiON passivated wafers. These flaws are believed to lead to      breakage of the device during processing, resulting in low fabrication yield. Both the power slump model and      the wafer breakage data show that these phenomena are dependent on residual stress developed in the      substrate during device fabrication. Reduction of process-induced residual stress should therefore      simultaneously decrease wafer breakage rates and reduce power slump during device fabrication and      operation.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  agallium arsenide aMESFET awafer breakage asemiconductor device ax-ray diffraction astress 2 aVirginia TechbMaterials Science and Engineering1 aRobert W. HendrickseCommittee ChairaAvraham AmithaRonald S. GordonaGuo-Quan LuaAicha Elshabini-Riad40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-394172159651721/ 02475ntm  2200205uu 4500008004100000035003000041100002300071245014700094256003000241260010300271502008200374504004100456520136300497538006801860538004301928653007301971710005302044720008902097856008302186      s1998    vau|    sm    00| 0|eng d  a(VPI) etd-2117142519725501 aWarren Jr., J.E.  00aNONLINEAR STABILITY ANALYSIS OF FRAME-TYPE STRUCTURES WITH RANDOM GEOMETRIC IMPERFECTIONS USING A TOTAL-LAGRANGIAN FINITE ELEMENT FORMULATION   aComputer data - 2 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1998  aThesis (PHD)--Virginia Polytechnic Institute and State University, 1998-07-12  aIncludes bibliographical references.3 aWith the increasing use of lightweight frame-type structures that span long distances, there is a need for a      method to determine the probability that a structure having random initial geometric imperfections will      become unstable at a load less than a spe cified fraction of the perfect critical load. The overall objective of      this dissertation is to present such a method for frame-type structures that become unstable at limit points.      The overall objective may be broken into three parts. The first part co ncerns the development of a      three-dimensional total Lagrangian beam finite element that is used to determine the critical load for the      structure. The second part deals with a least squares method for modeling the random initial imperfections      using the mo de shapes from a linear buckling analysis, and a specified maximum allowable magnitude for the      imperfection at any imperfect node in the structure. The third part deals with the calculation of the      probability of failure using a combined response surface/ first-order second-moment method. Numerical      results are presented for two example problems, and indicate that the proposed method is reasonably      accurate. Several problems with the proposed method were noted during the course of this work and are      discuss ed in the final chapter.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  aReliability aImperfection aStability aFinite Element aNonlinear 2 aVirginia TechbEngineering Science and Mechanics1 aS. M. HolzeraS. ThangjithameCommittee ChairaD. T. MookaD. H. MorrisaR. H. Plaut40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-211714251972550/ 01513ntm  2200205uu 4500008004100000035003100041100002200072245008100094256003000175260010300205502008200308504004100390520052100431538006800952538004301020653001001063710003001073720012001103856008401223      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-32131722397211111 aWatson, George W 00aBeyond the Psychological Contract: Ideology and the Economic Social Contract  aComputer data - 4 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (PHD)--Virginia Polytechnic Institute and State University, 1997-05-24  aIncludes bibliographical references.3 aBy combining normative philosophy and empirical social science, I craft a research framework for assessing      differential expectations of economic justice within the economic social contract of the United States. I argue      that distinct viewsof such a contract grounded in the tradition of individualism and communitarianism      manifest in people's judgments about economic justice. We empirically test these hypotheses on a sample of      270 subjects, finding broad support for the theoretical framework.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  anone 2 aVirginia TechbManagement1 aAnthony T. CobbaRichard WokutchaCarroll U. StephensaR.J. HarveyaJohn ChristmanaJon M. ShepardeCommittee Chair40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-3213172239721111/ 02983ntm  2200205uu 4500008004100000035003100041100002400072245006800096256003000164260010300194502008100297504004100378520204900419538006802468538004302536653001002579710003902589720006502628856008402693      s1997    vau|    sm    00| 0|eng d  a(VPI) etd-15541921497314011 aWeissbart, Erich J 00aThe Leached Layer Formed On Wollastonite In An Acid Environment  aComputer data - 6 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1997  aThesis (MS)--Virginia Polytechnic Institute and State University, 1997-04-29  aIncludes bibliographical references.3 aTHE LEACHED LAYER FORMED ON WOLLASTONITE IN AN ACID ENVIRONMENT Erich J.      Weissbart (ABSTRACT) Experiments were carried out in a fixed-bed external recycle mixed flow reactor to      measure the rate of dissolution and the development of a leached layer on wollastonite. Each experiment ran      for approximately 24 hours and the release rates of Si and Ca in the interval from 14 to 24 hours were      analyzed. Each experiment began with an incongruent stage where Ca was released faster than the silica that      remained on the surface to form the leached layer. The silica release rate after 14 hours was 2.13 x 10-9 (      1.03 x 10-9, 1 , n=67) mol/m2/sec, and this rate appeared to be independent of pH from pH 2 to 6 at 25      degrees C. BET surface area measurements of reacted wollastonite showed large increases in BET Asp over      the course of experiments even though both the Ca and Si release rates decreased. These large increases of      measured Asp were the result of the growing internal porosity of the leached layer, and much of this surface      does not seem to contribute to Si release rates. From these data, we infer that the overall reaction for the      hydrolysis of wollastonite in an acid environment is best explained by two relatively independent reactions.      First, Ca is removed from the crystal leaving behind linear silica polymers; then the silica polymers are      released into solution where they hydrolyze to form H4SiO4. nCaSiO3 + 2nH+ nCa2+ + (H2SiO3)n      (H2SiO3)n + nH2O n(H4SiO4) As the leached layer grows in thickness, the Ca release rate slows because it is      controlled by transport through the leached layer. A model of Ca diffusion through the leached layer shows      that the leached layer grows thicker at lower pH and presents a longer diffusion path for Ca transport into the      solution. This diffusion limited reaction offsets the faster rate of the Ca hydrolysis reaction so that at steady      state the Ca rates should also become equal to the Si release rate.    aSystem requirements: PC, World Wide Web Browser and PDF reader.  aAvailable electronically via Internet.  anone 2 aVirginia TechbGeological Sciences1 aM. F. HochellaaJ. R. CraigaJ. D. RimstidteCommittee Chair40zunrestricteduhttp://scholar.lib.vt.edu/theses/available/etd-1554192149731401/ 03327ntm  2200205uu 4500008004100000035003100041100002200072245007100094256003000165260010300195502008200298504004100380520219700421538006802618538004302686653007002729710004802799720019002847856008403037      s1998    vau|    sm    00| 0|eng d  a(VPI) etd-48571728397111711 aWilcox, Karen L. 00aPRIVILEGE IN FAMILIES: COMPLEXITY IN ADULT SIBLING RELATIONSHIPS    aComputer data - 3 file(s)  aBlacksburg, Va. bUniversity Libraries, Virginia Polytechnic Institue and State University, c1998  aThesis (PHD)--Virginia Polytechnic Institute and State University, 1998-07-12  aIncludes bibliographical references.3 a      The purpose of this study was to examine privilege in families and uncover the complexities of sibling      relationships in adulthood. Through interviewing 13 adult siblings and 3 mothers from 4 families my goal      was to gain a clearer picture of what privilege in families means. The sample consisted of a family with 3      sisters, a family with 3 brothers and a sister, a family with 4 brothers, and a family with 2 brothers and a      sister. The adult siblings ranged in age from 30 to 60, with an average age of 42. The mothers ranged in age      from 62 to 70, with an average age of 67. The study was guided by three theoretical frameworks: a life      course, a phenomenological, and a feminist perspective. I conducted this study utilizing an integration of      qualitative and feminist methodologies. I used a snowball sampling technique to recruit participants. Data      were collected through the use of qualitative in-depth interviews. The interview guides were developed based      on the research questions, the review of literature, and the theories guiding the study. I draw 5 conclusions      from this study. First, there is a sense of devotion to family that is both expected and fulfilled by simply      spending time together, being there for each other in times of need, and at times compromising personal      needs or wants. Second, there is an overarching sense of justice that is discussed in everyday language, but at      the same time referred to as "som