Dissertations / Theses: 'LD5655.V855 1988.C767' – Grafiati (2024)

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The phenomenon of transition in a laminar flow has been a topic of continued interest for many years. Recent experiments in shear flows have revealed a series of instabilities that lead to breakdown to turbulence. We have completed an analysis of the mechanisms which drive the primary (TS wave) and secondary instabilities in plane Poiseuille flow. This was accomplished by studying the solutions of linear primary and secondary stability theory with energy methods. We found that primary instability occurred when the viscous stresses overpowered dissipative forces near the channel walls. For the secondary instability, we saw that the TS wave catalyzes the instability and then mediates the transfer of brge amounts of energy from the mean flow into the three-dimensional disturbance, thus driving the instability. In addition, we have compiled an extensive catalog of the loc!l.l energy and vorticity field distributions which result from each instability.
Master of Science

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A detailed statistical study was performed on molluscan fossil assemblages collected from the Pliocene Morgarts Beach Member of the Yorktown Formation, located in Isle of Wight County, southeast Virginia. The principal objectives of this study were to examine potential sampling problems and biases inherent in paleontological research. This has been accomplished by statistically testing for the hom*ogeneity, or lack thereof, in species assemblages obtained from samples collected from three localities within the Morgarts Beach Member. Multivariate analysis of variance, two-way analysis of variance, multiple comparison tests and cluster analysis were performed on data collected from a five horizon by five section sampling grid (18 feet [5.5 meters] high, 21 feet [6.4 meters] long) located at Morgarts Beach, Virginia. The results of this analysis demonstrate that the relative abundances of species present in the five horizons are significantly different, whereas the relative abundances of species present in the five sections are not significantly different. Results from cluster analysis show that species assemblages contained in samples collected from the Morgarts Beach Member located at Rushmere are substantially different from the Morgarts Beach type area assemblages, in terms of relative abundances of species. The reason for the lack of faunal similarity relates to the documented facies change between the two localities. The results demonstrate that there is no reliable method to obtain accurate census data (frequency abundance curves) from biostratigraphic or lithostratigraphic units deposited during anything but a restricted time interval. In addition, replicate sampling was found to be unnecessary when attempting to determine the relative abundances of species contained in closely spaced sections within the Morgarts Beach Member. Species accumulation curves were constructed from the data collected from the Morgarts Beach Member. Examination of these curves demonstrate that many rare species will not be found unless extensive collecting is undertaken.
Master of Science

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The conventional theoretical and analytical debate surroundingcontemporary African underdevelopment attempts toclassify or label the impediments to development primarilywithin an internal-external dichotomy_ This thesis questionsthe internal-external approach in that it may limit the opportunityto examine the situation more in terms of a singleprocess, blending the forces that hinder political and economicgrowth. The case of the Sudan illustrates this'holistic' concept in that certain fundamental constraintswi thin the Sudan combined with specific external factorsplace severe limitations on both the economic and politicaldevelopment of the country. The tradi tional disunity andabsence of a legitimate political authority within the Sudan,combined with the Sudan's inteqration into the world economicsystem, has created a situation that is detrimental to development.Rather than place the blame or responsibility forunderdevelopment on any particular set of forces, t have examinedhow these forces have intertwined to create the present conditions in the Sudan, perhaps highlighting similarsituations throughout other Third World nations as well.
Master of Arts

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Thirty nonparent adults were assigned to either a High CAP group (n=15) or a Low CAP group (n=15) based upon their scores on the Child Abuse Potential Inventory. Each subject's heart rate, skin conductance level and diastolic blood pressure were assessed while listening to a series of 4 high- and 4 normal-pitched infant cries. Subjects then rated the same cries on 6 perceptual scale items. Results indicated that the adults in the High CAP group showed a reliably higher resting heart rate following cry presentation and tended to respond with more heart rate change than adults in the Low CAP group. Adults in the High CAP group also responded to the normal-pitched cries with a higher skin conductance level than the Low CAP adults. Irrespective of CAP group, listeners' skin conductance level became attenuated in response to the normal-, but not the high-pitched infant cry sounds.In addition, all listeners perceived the high-pitched cry sounds as more aversive, arousing, distressing, urgent and sick sounding than the normal-pitched cry sounds. Results are discussed in terms of the importance of examining both adult and child characteristics that may mediate individual responsivity to infant cues.
M.S.

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Following the concepts of stability analysis, a study is made of the pre-breakdown stage of transition to turbulence in boundary layers. The first step consists of a ’decoupling’ of the primary and secondary instabilities. A perturbation method is used to solve for the primary wave, in the absence of any secondary disturbances. Once the wave is calculated, it is decomposed into a basic flow portion and an interaction portion. The basic flow portion acts as a parametric excitation for the secondary wave. The interaction portion then captures the resonance effects of the secondary back onto the primary. A perturbation method is also used for the secondary and interaction components. The results obtained are in three principal forms: Landau constants, amplitude growth curves, and velocity functions. While in good agreement with experiments and simulations, these results offer new explanations to the observed processes. In addition, a physically-based transition criteria is established.
Ph. D.

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Traditional higher education institutions are being admonished by federal commissions as well as scholars for being unresponsive to student and societal needs. Several studies have pointed out the growth of proprietary and corporate postsecondary education programs at the expense of market share formerly enjoyed by traditional higher educational institutions. There is considerable conflict among scholars, businessmen, and commissions on what higher education institutions should do to be more responsive.The major objectives of the market research study were to determine the following: (1) What potential students' long-term goals were and (2) What expectations that had for educational institutions contributing to realization of those goals. The theoretical foundation for this study was Vroom's expectancy theory in which he hypothesized that motivation was a function of valence or value of individual goals and the expectancy of realizing those goals through individual effort and the instrumentality of an organization.A random sample of potential students was asked to put in order or priority five major goals and expectations for achieving those goals through various means, ranging from educational effort through luck.The results and conclusions of this study were: (a) In general all socio-economic groups were in agreement on goals--making money and good health among others. Most agreed that luck, rather than any effort on their part, would be the main instrumentality for achieving good health; (b) Education and hard work were perceived as the most likely means for obtaining money; (c) Those with previous higher education experiences valued it more as a means to obtain goals/values than did those with little higher education.
Ed. D.

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With a great amount of research currently being aimed towards dynamic analysis and control of very large, flexible structures, the need for accurate knowledge of the properties of a structure in terms of the mass, damping, and stiffness matrices is of extreme importance. Typical problems associated with existing structural model identification methods are: (i) non-unique solutions may be obtained when utilizing only free-response measurements (unless some parameters are fixed at their nominal values), (ii) convergence may be difficult to achieve if the initial estimate of the parameters is not "close" to the truth, (iii) physically unrealistic coupling in the system matrices may occur as a consequence of the identification process, (iv) large, highly redundant parameter sets may be required to characterize the system, and (v) large measurement sets may be required. To overcome these problems, a novel identification technique is developed in this dissertation to determine the mass, damping, and stiffness matrices of an undamped, lightly damped, or significantly damped structure from a small set of measurements of both free-response data (natural frequencies, damping factors) and forced-response data (frequency response functions). The identification method is first developed for undamped structures. Through use of the spectral decomposition of the frequency response matrix and the orthogonality properties of the mode shapes, a unique identification of the mass and stiffness matrices is obtained. The method is also shown to be easily incorporated into a substructure synthesis package for identifying high-order systems. The method is then extended to include viscous damped structures. A matrix perturbation approach is developed for lightly damped structures, in which the mass and stiffness matrices are identified using the imaginary components of the measured eigenvalues and, as a post-processor, the damping matrix is obtained from the real components of the measured eigenvalues. For significantly damped structures, the mass, dauping, and stiffness matrices are identified simultaneously. A simple, practical method is also developed for identification of the time-varying relaxation modulus associated with a viscoelastic structure. By assuming time-localized elastic behavior, the relaxation modulus is determined from a series of identification tests performed at various times throughout the response history. Many interesting examples are presented throughout the dissertation to illustrate the applicability and potential of the identification method. It is observed from the numerical results that the uniquely identified structure agrees with simulated measurements of both free and forced·response records.
Ph. D.

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This thesis is an attempt to arrive at a poetic form for a house in a city. It is a form that relies an the nakedness of things (walls, columns and platforms) to define a space.
Master of Architecture

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A method of predictive control is used in the regulation of a vehicles' speed in an environmental test cell with a wind tunnel. The vehicle speed is regulated through the throttle while the vehicle torque is controlled with a dynamometer. The predicted throttle position for the requested speed is based on torque, speed, and throttle position curves. The predictive control works in conjunction with an integrating speed regulator. The predictive control sets the throttle position when the speed error is above a set limit. Otherwise, the integrating regulator controls the speed. A description of both the dynamometer and throttle control hardware is included in the thesis. The throttle control software is described in detail since most of the regulating functions are digital. Both simulation and on-site tests are described. Test results are provided by strip chart recordings.
Master of Science

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A Prolog based approach towards the recognition of logic functional blocks in CMOS circuits is described in this thesis. A transistor level description of the circuit is assumed to be available. Predefined gates and logic blocks are extracted from such a description. This recognition procedure is a step towards raising the level of description of a network. An extracted block level description can be used to verify the correctness of the implemented logic. The approach described here uses a circuit partitioning technique to divide a given circuit into smaller subcircuits. This is followed by the extraction of logic expressions at the output nodes of subcircuits. From these logic expressions, gates are recognized. Functional blocks in the circuit are recognized based on rules which define such blocks in terms of their structural configuration.
Master of Science

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A finite element program for analyzing the nonlinear behavior of moving contact problems hasbeen developed and used for the analysis of a single sheet pile interlock (Chan and Barker (1985),Wu and Barker (1986). In this study, the program is modified to simulate a sheet pile pull-out testwith a new finite element mesh. The improved mesh contains a full-length sheet pile with both ofits interlocks connected to two half-length sheet piles. The results are presented and compared withthe results of the pull-out tests which were conducted by O'Neil and McDonald at WES (1985).The comparison is not completely satisfactory because the initial slack between interlocks is notmodeled. Nonetheless, the general behavior of sheet piles under tensile load is correctly predictedby the finite element program.

For easier interpretation of the output from the finite element analysis, the computer graphicssoftware AutoCAD (Auto desk, 1986) is adopted to serve as a postprocessor. Several features ofAutoCAD such as overlaying, zooming, and macro instructions are utilized to serve this purpose.Some intermediate programs are also developed for the communication between the finite elementprogram and AutoCAD.
Master of Science

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This study examines the economic performance of Asianimmigrants during their first years in the United States.The earnings levels of Japanese, Chinese, Filipino, Korean,and Vietnamese immigrants entering the U.S. between 1975 and1979 were compared with the usual earnings patterns of immigrantsfound in the work of Barry Chiswick. The primaryfactors influencing the earnings levels of people indifferent immigrant groups were found to be the transferabilityof skills and levels of self-selection. Thesefactors are to be expected when using a study frameworkbased on a conventional human capital model. Earningsequations were estimated using 1980 Census data to measureearnings differentials between new Asian immigrants and thenative-born. The earnings levels of refugees (Vietnamese)and economic immigrants (Japanese, Chinese, Filipino, andKorean) were compared to identify differences.

Master of Arts

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Parallel manipulators are being thought of as a solution to many problems involving controland manipulation. They offer significant advantages over serial manipulators in terms of increasedstrength and rigidity. Variable geometry trusses (VGTs) are a special class of paralleltrusses.

Literature on VGTs has covered many interesting problems, yet there has been no consciouseffort to formulate a definition for a VGT. The major emphasis of this thesis is developing aset of precise kinematic rules for defining and analyzing VGTs.Traditional mobility criteria, when applied to parallel geometries, predict results which areoften confusing and sometimes inaccurate. Based on the set of rules developed, mobilityequations are derived for planar and spatial VGTs. The equations are tested on a sufficientlylarge number of VGT configurations to convince the author about the validity of the set of rulesand the equations derived. Using the mobility equations, different candidate geometries canbe analyzed and compared. In addition, the equations can be used in the type and numbersynthesis of VGTs.

Master of Science

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The localization of modes of nearly periodic structures causes a concentration of energyin one part of the mode shape. It occurs for a disordered structure with weakly coupledsubsystems. The forced excitation of localized modes may affect the maximum responseamplitude of the system. Two nearly periodic structures are analyzed herein: a two spanbeam and a pair of coupled pendula. Results show that the sensitivity of the forcedresponse to the degree of localization depends on a combination of the symmetry of themode which is excited and the phase difference between the forces acting on eachsubstructure. These results attempt to explain the range of contrasting conclusions ofprevious research on the effects of forced response on mistuned structures.Furthermore, a theoretical explanation of the results is given in terms of transfer admittance.A probabilistic analysis of the free and forced response of a nearly periodic structure isshown to be useful in the design of such structures which are sensitive to the degree of localization. The second moment method is used in the analysis with results verified byMonte Carlo simulation. The probabilities of localization and failure are calculated giventhe statistics of the system parameters, and the localization and failure tolerances respectively.
Master of Science

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Soluble and insoluble non-starch polysaccharide (NSP) fractions have been isolated from the pulp of ripe banana fruit. Attempts to determine the composition of the insoluble NSP indicated the fraction to be exceptionally complex and difficult to analyze. Only about 44% of the dry weight could be accounted for as NSP, the protein content was high (26%) and about 22% of the dry weight appeared to be a complex mixture of phenolic and other unknown components. One interesting property of the insoluble NSP was its unusually high water-holding capacity. The soluble NSP (isolated by extraction from fresh pulp with water at 25°C and not dried prior to analysis) contained about 48% pectin, 20% hemicellulose, 21% partially hydrolyzable polysaccharides and 11% protein. The hemicellulose represented about 0.05% of the banana fresh weight or about 0.2% of dry weight. Hydrolysis of the hemicellulose and analysis of the resulting sugars via gas chromatography revealed the hemicellulose to be made up predominantly (84%) of mannose, the remainder being 12% arabinose and 4% xylose. After removal of most of the pectin via treatment with anion exchange resin, the major hemicellulose component was isolated by gel filtration. The isolated hemicellulose was a hom*omannan as demonstrated by gas chromatography and high performance liquid chromatography of acid hydrolysates. The banana hom*omannan appears to be unique among plant mannans. All previously isolated plant hom*omannans were reported to be insoluble in water. Further studies will be required to establish the exact structure of the banana mannan. The molecular weight (MW) of the mannan in solution appears to be exceptionally high, the peak MW being about 5 million, as determined by gel filtration.
Master of Science

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The problem of this study was to examine errors located by subjects proofreading hardcopy versus softcopy business documents. Hardcopy refers to a business document typed or printed on paper; softcopy refers to a business document displayed on a computer screen. Data were obtained by 61 Southwest Virginia high school business students completing a background information sheet and proofreading the same three documents—a letter, a report, and a memo—on both hardcopy and softcopy media; for each media, the students proofread each document for 15 to 20 minutes over a 1-hour period. The number and types of errors found, the number of times each document was proofread, and personal characteristics of the subjects were analyzed.The following outcomes are based on the results of the study: (a) subjects located the same number of errors when proofreading from hardcopy and softcopy media; (b) subjects located one to two more errors in the letters and reports than in the memos; (c) the medium was not related to the specific types of errors found; (d) subjects who proofread a document five times located one to two more errors than those who proofread fewer times; (e) subjects with 0 to 2 years of computer experience located one more error than those with more experience.The two main conclusions of the study were: (a) students need not print hardcopies of documents in an attempt to locate more errors than in softcopy documents; and (b) teachers should be aware that students are more likely to locate some types of errors than others.
Master of Science

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The effects caused by a variation of the key parameters involved in a proprietary process for the production of microporous polyethylene were investigated. The process involved the treating of a polyethylene film with two proprietary solutions at specific temperatures and in some cases required stretching of the material in the solutions. Specialized equipment was developed to implement the process and determine the conditions under which porous material was produced. The effects of changing these process conditions on the porous nature of the material produced was then determined. lt was determined that for the particular polyethylene film chosen for the investigation, the most uniform porous material resulted when the film was treated with the two proprietary solutions without the use of stretching. The conditions in the first solution were found to be the most important in determining the nature of the material produced. Pore size and distribution were not significantly altered in the variation of the parameters investigated. The material produced had an average pore size of 0.17 micron and a pore density of 0.9 x 10⁹ pores/cm2. The yield point of this material was found to range from 610 - 840 psl (4.2 - 5.8 MPa).
Master of Science
incomplete_metadata

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This study examined shrinkage and related characteristics of two North American varieties of lodgepole pine: Pinus contorta var. latifolia and Pinus contorta var. murrayana, sampled at 10% of tree height.For var. murrayana, size was the only factor that had a significant effect on specific gravity; specific gravity decreased with increasing tree diameter. For var. Iatifolia, latitude was the only factor that had a significant effect on specific gravity; in general, specific gravity increased with increasing latitude. Conversely, specific gravity had a significant effect on radial shrinkage, the radial shrinkage tangential shrinkage ratio, and volumetric shrinkage for both varieties. The analysis of variance procedure indicated that the factors size, latitude, and elevation had no effect on the shrinkage of var. Iatifolia. However, for var. murrayana, radial shrinkage was affected by both tree size and latitude. Tangential shrinkage was also affected by latitude (increasing with increasing latitude).Linear correlations between radial shrinkage and growth rate, longitudinal shrinkage and distance I from the pith (a negative relationship), and specific gravity and growth rate were highly significant for both varieties. For var. Iatifolia, the linear association between specific gravity and heartwood percent was also significant.For var. murrayana, no difference in shrinkage or specific gravity was detected between the heartwood and sapwood. For var. Iatifolia, heartwood shrank less radially and had a lower specific gravity than sapwood.A comparison of the two varieties at their common latitudes indicated that murrayana trees have both higher specific gravity and shrinkage than do Iatifolia trees of the same size.
Master of Science

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Chord keyboards use the concept of simultaneous activation of keys to produce single characters. Some chord keyboards have been suggested as potential devices to replace the standard QWERTY keyboard which is now considered the major human-computer interface tool.This study focused on evaluating a new chord keyboard that uses a set of eight ternary (3 state) keys. An experimental comparison of the ternary chord keyboard (TCK) with the QWERTY keyboard was conducted. Two groups of subjects were selected to participate in the study. One group was assigned to the QWERTY keyboard and the other to the TCK. The two groups learned to input a set of 17 characters. Training of each group was similar and the stimuli were identical. The study investigated how the two groups compared in attaining certain performance criteria (speed and accuracy), and how performances compared on both keyboards after fulfilling the criteria.For each group, the number of sessions to reach the criteria was recorded along with speed and accuracy of typing. At the end of the experimental session, subjects rated some features of their respective keyboard. Performances on both keyboards were comparable in all stages with no significant differences revealed. However, executing chords on the TCK was rated significantly more difficult than activating keys on the QWERTY keyboard.
Master of Science

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Karyotypes of nine species of Venezuelan annual killifishes were compared. Karyotypic differences were found between species and between some genera.

A chromosomal sexual dimorphism was found in Pterolebias hoignei (2N = 46). Males of this species possess a single large "Y" chromosome. No chromosomal divergence was detected among conspecific populations from different localities. Pterolebias hoignei and Pterolebias zonatus were found to differ both in diploid number (46 and 42 respectively) and in metacentric chromosome number (6 and 12 respectively).

All Rachoviaspecies were found to have a diploid number of 44. Rachovia maculipinnisand R. brevis were found to differ from one another in metacentric chromosome number (20 and 12 respectively). Rachovia hummelincki and R. pyropunctata both possess metacentric chromosome counts of 10.

No karyotypic differences were found between Austrofundulus transilis and Austrofundulus limnaeus (2N = 44, metacentrics = 12). Several populations of the latter although divergent in male color patterns, did not differ karyotypically. All species examined, except Rivulus stellifer, departed from the presumptive ancestral teleost diploid number of 48. The degree of chromosomal variation appears not to be as high among the New World as among the Old World annuals. This difference among lineages with similar life histories and reproductive strategies suggests that stochastic events have not played a major role in mediating chromosomal divergence in annual fishes.

Master of Science

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In this research we develop an integrated approach to optimally sequence robot operationin a workcell. The workcell represents a f1owshop operation with multiple robots transportingjobs among machines. A buffer of infinite capacity is available ahead of each machine.A robot transports jobs from buffers to machines and from machines to buffers. The robotsused in the system are 5 jOint cylindrical coordinate robots. All the robots are identical in designand capability. For the type of robot used in this study its closed form inverse kinematicsolution is known. The objective is to determine the sequence of robot operations so as tominimize the total time needed to complete all jobs (known as makespan).

The integrated approach consists of determining optimal robot task sequences using abranch and bound procedure. and a graphical simulation procedure to display the robots asthey perform transport operation. The branch and bound algorithm, which is an implicit enumerationscheme, is used to derive several near optimal robot task sequences. For thebranch and bound algorithm. each node is a transport operation. Lower bound on themakespan is machine based and is computed at each node for further branching. The graphicalsimulation is used to detect interference among robots which is hard to be incorporatedin the branch and bound procedure. Infeasible robot sequences are discarded and other solutionsfrom the branch and bound procedure are displayed using the graphical simulationprocedure to determine a near optimal and feasible sequence.

The integrated approach is implemented on a prototype system. A command drivengeneral purpose graphics system MOVIE.BYU is used for the graphical simulation of therobotic workcell and robot motion. The entire system is available in an integrated environment.A powerful programming language Rexx is used to manage various programs and data.Also, intermediate Rexx programs are generated during execution to allow MOVIE.BYU to editand display animation data on the Tektronix 41XX series of terminals. The entire system isflexible and modular to be able to be used for various different applications.
Master of Science

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Gluconobacter oxydans is characterized by extreme acid tolerance and the ability to carry out rapid, single-step polyol oxidation catalyzed by membrane bound ehydrogenases. Experiments were designed to determine whether acid tolerance is associated with rapid polyol oxidation in this organism. Washed cells were exposed to 0.1 M or 0.5 !vt NaCI at pH 3.20; subsequent alkalinization of the suspending solution suggested a NaCl-dependent flow of protons (H+) into the cells. Cells were then exposed to NaCI at pH 3.20 followed by the addition of glycerol to determine whether polyol oxidation resulted in H + explusion from the cells. Following glycerol addition, immediate acidification of the suspending solution occurred. To verify that H + effiux was a result of respiration, experiments were conducted using sodium azide and 2,4-dinitrophenol; both compounds prevented the acidification that otherwise occurred following glycerol addition. Because glycerol oxidation reversed the NaCl-induced flow of H + into the cell, it appeared that respiration might function to protect acid-labile cell interiors. Cells exposed to NaCl at pH 3.20 in the presence of glycerol maintained cellular viability while loss of viability occurred in the absence of glyceroL To verify the effect of H+ extrusion on pH homeostasis, radioactively labeled organic-acid probes were used to determine intracellular pH in respiring and nonrespiring cells in the presence of 0.1 M NaCI at pH 3.20. No differences in cytoplasmic pH values between respiring and nonrespiring cells were detected. However, because substantial evidence exists for the role of respiration dependent H + extrusion in the acid tolerance of G. oxydans, use of an alternate method for measurement of internal pH, such as 31 P nuclear magnetic resonance spectroscopy, is suggested.
Master of Science

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The principal purpose of this investigation was tosynthesize and hydrogenate well-characterized linear andstar-branched block copolymers based on butadiene andisoprene. Sequential anionic addition techniques initiatedby hom*ogeneous organolithium species in hydrocarbon solventswere employed to prepare several series of butadiene-isoprenecopolymers varying in block size and architecture.Linear Aâ Bâ A poly(butadieneâ isopreneâ butadiene) triblockcopolymers were synthesized by two different living additiontechniques, e.g., three-stage process using a monofunctionalanionic initiator and a two-stage process using adifunctional anionic initiator. Alternatively, the synthesisof star block copolymers involved the sequentialpolymerization of poly(butadiene-isoprene) diblock arms whichwere then linked into stars via divinylbenzene.Hydrogenation of unsaturated polymers has widelyattracted attention since this provides an alternate methodfor improving and optimizing the mechanical, thermal,oxidative and chemical resistance properties of thesetechnological important materials.hom*ogeneous catalytic hydrogenation was employed tochemically modify these linear and star-branched copolymerinto thermoplastic elastomers. Hydrogenation successfullyconverted the soft polybutadiene blocks into hardsemicrystalline polyethylene segments, while the centralpolyisoprene blocks resulted in the formation of amorphousalternating rubbery copolymers of propylene-ethylene. Thehard semicrystalline blocks form morphological domains thatserve as physical crosslinking and reinforcement sites.The presence of semicrystalline segments in both thelinear and starâ branched copolymers has importantsignificance for processing. Above the endothermic meltingtemperature of the semicrystalline end. blocks, the nowamorphous system can approach the melt behavior of a singlephasemelt, that is, displaying negligible "physical" networkstructure in the melt. Overall, these systems display avaluable combination of good melt processability togetherwith physical properties characteristic of A-Bâ Aarchitectures.
Master of Science

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Every one who has driven on a freeway has observed the phenomenon of lanechanging. This phenomenon is, of course, caused by the desire of most of the drivers not to be in a slow-moving lane. Therefore, the average driver who finds himself in such a lane moves into a neighboring faster lane, usually after a certain time-lag. This time-lag depends on the dynamic characteristics of the vehicle, the availability of acceptable gaps, and the driver risk, which is the value the driver places on the probability of collision during a maneuver, i.e. the higher the perceived probability of collision, the higher the time-lag. Modelling of the lane-changing phenomenon has been the objective of many investigators in the past. As will be shown later in this study, lane-changing is a very important component in highway traffic flow. In this study, a mathematical model to describe the lane-changing behaviour is suggested based on the lane-changing hypothesis that whenever there is a lane-changing maneuver, the average speed of the neighboring lane is faster than the average speed of the current lane. A set of data has been collected by a methodology which involves aerial photographic technique. The collected data are then used to test the validity of the lanechanging hypothesis, to calibrate and validate an existing lane-changing model, and to develop a gap acceptance function for freeway lane-changing maneuvers.
Master of Science

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With the increased utilization of whey powders in food products there is a need to investigate the storage stability of whey powders. The objectives were to determine the effects that compositional factors of whey powders had on the Maillard reaction during storage. The Maillard reaction is the major deteriorative reaction limiting the shelf-life of whey powders. Eight commercial whey powders were stored at accelerated storage conditions (35°C) and at five different water activities, a_ws, (0.32, 0.44, 0.52, 0.63, and 0.74) for up to 120 days. Small quantities of the hydrolyzates of lactose- glucose and galactose (less than 2% dry wt.) caused a sizable increase in the relative rates of the Maillard reaction in whey powders. The relative rate of the Maillard reaction rate was determined by measuring brown pigment formation at 420 nm. Increasing the amount of nonprotein nitrogen (NPN) significantly increased the relative rates of the Maillard reaction in the whey powders. Increasing ash content had a positive but statistically insignificant effect on the Maillard reaction. The influence of water activity on the storage stability of whey powders was also investigated. Increasing the protein content of the whey powders increased the a_w, where the maximum rate of brown pigment formation was observed. In the highest protein whey powders (46% and 82%) however, the browning rate maxima shifted to lower a_ws. The loss in protein quality of the whey powders was determined by examining the loss of available lysine using the dye-binding method. Intermediate protein whey powders (31-40% protein) and unprocessed sweet dried wheys lost the greatest relative percentages of available lysine during the storage period.
Master of Science

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A virulent Mycobacterium avium strain, LR25, which carries 3 plasmids (18, 28, and 165 kb) and grows at 43°C was compared to its plasmid-free, avirulent segregant, strain LR163, to investigate the basis for the latter's inability to grow at 43°C. The failure of mid-log phase cultures of strain LR163 to grow at 43°C was dependent upon the presence of high levels of culture aeration. In addition, highly aerated mid-log phase cultures of strain LR163 failed to grow at 379C, By contrast, late-log phase cultures of strain LR163 were capable of growth when shifted to 43°9C under highly aerobie conditions. Mid-log phase cells of strain LR163 had 30% of the catalase activity of mid-log phase cells of strain LR25 and were more susceptible to hydrogen peroxide (0.08% w/v). Catalase activities of late-log, early-stationary, and stationary phase cells of strain LR163 were Significantly higher than mid-log phase cells. Catalase activity of strain LR25 was highest in cells of mid-log phase cultures, whereas the catalase activity of strain LR163 was highest in cells of stationary phase cultures. These data support the idea that plasmid-encoded genes influence M. avium catalase activity.
Master of Science

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The counting and classification of vehicles is an important part of transportation engineering.In the past twenty years many automated systems have been developed to accomplishthat labor-intensive task. Unfortunately most of those systems are characterized byinaccurate detection systems and/or classification method's which result in many classificationerrors, thus limiting the accuracy of the system.This report describes the development of a new vehicle classification program, originallydesigned for use in the Two-Point-Time-Ratio method of vehicle classification, which couldgreatly improve the accuracy of automated classification systems. The program utilizes dataprovided by either vehicle detection sensors, or the program user, to determine the velocity,number of axles, and axle spacings of a passing vehicle. It then matches the axle numbersand spacings with one of forty-one possible vehicle classifications and prints the vehicle class,speed, and wheelbase lengths. It also tabulates and prints totals and average speeds for eachvehicle type.This report then describes a roadside experiment conducted to test the accuracy of theprogram, and the results of that experiment, which show the program classifications to behighly accurate.The report then describes the options available within the program, and provides instructionsand an example on the use of the program. Possible future expansions of the systemare also cited.
Master of Science

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The personal computer program MOVEX, a program for the design of structurally supported excavations to limit X lateral ground movements in clay soils, was revised and updated. A key element in the program, the method of determining factor of safety against basal heave, was fully rewritten. Seven case histories were examined to evaluate the program capabilities in predicting movements.Two important improvements to the program include adding allowances for possible anisotropic strength variations in the soil layers, and for wall movements caused by excavation before supports are added to the wall. The latter issue is relevant inasmuch as such movements are present in almost all excavations to one degree or another. The program output was also updated using a streamlined and more informative format. Disclaimer statements were added to certain areas to notify the user of program limitations. Movement calculation methods were improved by removing several errors and adding a linear interpolation feature which eliminates our earlier problem with jumps in predictions as certain parameter horizons were passed. Finally, the Fortran program was reorganized and commentstatements were added to provide a more flowing and readable style, and a new User's Guide was developed to reflect the new program.
Master of Science

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The study extended the Scott et al. (1985) research by examining the influence of publicrecognition on employees' attitudes and perceptions toward absenteeism. The main focuswas on why the public recognition program was effective in reducing employee absenteeism.

To better understand the effectiveness of recognition in reducing absenteeism, a modelof the absenteeism/recognition relationship was developed. The model was based on theintegration of the need, expectancy, reinforcement, and goal setting theories. It impliesthat the influence of recognition on attendance behavior is a function of an employee's (1) desire for recognition; (2) belief that attendance is related to recognition; (3)personal attendance goal setting which is a function of an employee's(a)perceived congruency between individual and management's attendance goals, (b) perceived reasonablenessof management's attendance goals, and (c) perceived ability to attend in order to meet goals; and(4) recognition award.

It was concluded that even though recognition programs have been shown to yieldgreater reductions in absenteeism than other approaches (e.g., lotteries, financial incentives,etc.), the reasons for its effectiveness are still not known.

Master of Science

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Abstract:

Dual purpose fiber optic microbend loss sensors have been developed formeasurement of underwater acoustic wave amplitudes and for detection of thedirection of wave propagation. Cylindrical sensing elements with external threadshave fibers wound around them. Axial slots, cut along the length of the cylinderand deeper than the threads, provide the microbends. Three differentconstruction schemes for cylindrical sensing elements are built. The dual purposehydrophones are characterized for frequencies ranging from 15 kHz to 75 kHz.Based on the results, an improved design that uses the wavelength dependenceof microbend loss in a single mode fiber is proposed.
Master of Science

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The effect of genetic selection for milk yield on lactation yield, net energy balance (NEB) and on plasma growth hormone (GH), insulin (INS), prolactin (PRL), nonesterified fatty acids (NEFA) and glucose was studied in primiparous Holstein cows. Net energy balance was calculated and serial blood samples were collected at 0, 45, 90, 180 d postpartum (dpp) and 14 d of the dry period over a 7 h period via jugular cannulae. After 2.5 h of blood collection, growth hormone releasing factor (GRF) was administered at 0, 45, 180 dpp and 14 day of the dry period, while epinephrine was administered at 90 dpp. Nonesterified fatty acids were quantified in 90 dpp samples only. Basal and response periods for each hormone and metabolite were compared by analysis of variance. Milk yield was greater (P<.05), NEB was decreased (P<.05) and plasma GH was greater (P<.05) in selection cows (high-yielders) compared to control cows (low-yielders), while PRL, INS, glucose and NEFA were not different. Growth hormone increased in both groups in response to GRF at all days postpartum measured, while PRL, INS and glucose were not altered. Epinephrine administration at 90 dpp, stimulated an increase in plasma NEFA, glucose and INS in both groups. Control cows showed a greater (P<.01) INS response than selection cows. Results indicate differences exist in GH concentration between genetically selected high- and low-yielding Holsteins during early lactation, but the question remains if these differences are due to energy balance differences or differences in genetic merit for milk yield.
Master of Science

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The practical applications of scheduling generally involve the optimization of more than one criterion. This thesis focuses on the bicriteria optimization problem of scheduling jobs on single and two machines. The optimization criteria that are considered are those of minimization of maximum tardiness and minimization of the total number of tardy jobs in the schedule. The former is considered as the primary criterion while the latter is considered as the secondary criterion. For the single machine problem, a search tree method is presented which is based on the implementation of some new dominance rules. Computational results presented show that the performance of this algorithm is better than that of an earlier work reported in the literature. For the two machine problem, a heuristic algorithm is developed to minimize maximum tardiness. Computational results are presented regarding the performance of this heuristic. A search tree method is developed for the optimization of the secondary criterion. This search tree method is similar to that for the single machine problem except that it does not use the dominance rules that were developed for the single machine case. Computational experience is presented for this algorithm.
Master of Science

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During the 1970s, the United States passed a series of laws regulating the handling and disposal of hazardous material. The new rules drastically increased the cost of processing toxic wastes. Consequently, many producers began investigating methods that would render toxic material non-hazardous. one solution developed was cement encapsulation, a process that incorporates toxic material into a cement matrix, thus solidifying the waste and reducing the potential for the migration of toxins into the environment. This process can be used to prepare a waste for disposal or can be used to develop a construction material, thus mitigating costs further. This solution was selected by Roanoke Electric Steel as a possible way to dispose of electric arc furnace dust, a by-product which contains a variety of heavy metals which are classified as hazardous by the United States Environmental Protection Agency. In this study, the furnace dust was incorporated into mortar as a portion of the fine aggregate. By including a chelating agent and a stabilizing agent, mortar was developed which meets the requirements of ASTM C150 with respect to strength and time of setting. The optimum mixture has a 28 day strength of 4500 psi and passed the EP Toxicity test, as required by the Environmental Protection Agency before a material can be delisted. To further validate the use of furnace dust in masonry products, the mortar was evaluated for its dimensional stability, both physical and chemical, and for its freezing and thawing durability characteristics.
Master of Science

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Inspired and subject to individual experience, an in depth study of eleven piazzas yielded a set of Architectural elements, characterizing each piazza. Clearly, "intention" supplements their unique evolution, and the layered symbolism over time, throughout the urban fabric, emits a specific disposition within each piazza.The consistent refinement of particular conditions developing from common initial intentions may lead to a basic Architectural criteria. Though not accepted as a universal standard, this criteria produces a set of characteristics applicable to a multitude of open spaces; hence, like the Italian Piazza, “accomplished space”.
Master of Architecture

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To create neural networks that work, one needs to specify a structure and the interconnection weights between each pair of connected computing elements. The structure of a network can be selected by the designer depending on the application, although the selection of interconnection weights is a much larger problem. Algorithms have been developed to alter the weights slightly in order to produce the desired results. Learning algorithms such as Hebb's rule, the Delta rule and error propagation have been used, with success, to learn the appropriate weights. The major objection to this class of algorithms is that one cannot specify what is not desired in the network in addition to what is desired. An alternate method to learning the correct interconnection weights is to evolve a network in an environment that rewards "good” behavior and punishes "bad" behavior, This technique allows interesting networks to appear which otherwise may not be discovered by other methods of learning. In order to teach a network the correct weights, this approach simply needs a direction where an acceptable solution can be obtained rather than a complete answer to the problem.
Master of Science

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Abstract:

A house for a stage for the event of poetic impulse. An architecture founded on the understanding of the fragment and the definition of place of being. A building of the acknowledgement of the rituals of man.
Master of Architecture

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Each and every material has certain inherent characteristics. When successfully evaluated for these characteristics a material’s true spirit becomes clear. Only when a material is completely understood can it be used properly. It is through the sensitive use of materials that architecture becomes rich. When considering materials, several issues come to bear. What "work" do they do? How do the materials interact most harmoniously? How do the materials touch? Do they need an intermediate material? How do they begin? End? To what level are their details taken? A whole world of consideration becomes apparent. The answers to these questions become an operational language through which design can occur. This language when applied to the built environment then becomes a structural language.
Master of Architecture

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The cellular slime mold, Dictyortelium dixcoideum, provides an ideal model system to study eukaryotic cell differentiation. In D. discoideum glycogen degradation provides precursors for the synthesis of developmentally regulated structural end products. The enzyme responsible for glycogen degradation, glycogen phosphorylase, exists in active and inactive forms. The activity of the ’a' form (the active form) is independent of 5′adenosine monophosphate (5′AMP) while the activity of the ’b' form (the inactive form) is 5′AMP dependent, The two forms are developmentally regulated. Polyclortal antibodies raised to the purified forms of this enzyme show low cross reactivity. The anti-’a' antiserum reacts with a 104 kd protein that is associated with phosphorylase ’a' activity; the anti-’b' antiserum reacts with a 92 kd protein that is associated with phosphorylase ’b' activity and cross reacts weakly with the 104 kd protein. Cyclic AMP perturbation of intact cells caused induction of both phosphorylase ’a' activity and the appearance of the 104 kd protein. lmmunotitration data suggest that the ’a’ form accumulates due to de novo protein synthesis, although this result must be interpreted with caution. In vitro translation experiments indicate that separate mRNA species exist for the two forms of phosphorylase. The mRNA for the 'b’ form is present throughout development while that of the ’a' form appears late in development.
Master of Science

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The complex and non-linear nature of blast fracturing have restricted common blast design mostlyto empirical approaches. The code developed for this investigation avoids both empiricism andlarge memory requirement in order to simulate the pattern of interacting radial fractures from anarray of shotholes, at various burdens and spacings, and in simultaneous and delayed modes. Theresultant pattern is analyzed and a fragment size distribution calculated.

The rules governing the distribution of radial cracks and the way in which they interact are basedon model scale experiments conducted by various investigators. Calculated fragment size- distributionagree with data from the field. Powder factor dependence of fragmentation results is also welldescribed by the model.

The effect of discontinuities on rock fragmentation by blasting is also incorporated into the model.Discontinuities which are open and filled with air or soil-like material affect destructively thetransmission of strain waves and propagation of cracks in the rock mass. These discontinuities canbe incorporated into the simulation by inserting cracks to represent them. The cracks representingdiscontinuities will then terminate the cracks produced by blasting where they intersect. On theother hand, tight joints without filling material or with filling material but with a high bond strengthand acoustic impedance close to that of the medium do not affect in a negative way the transmissionof shock waves in the rock mass. A mathematical model was developed to treat these discontinuitieswhich was based on principles from Linear Elastic Fracture Mechanics theory and Kuznetsov'sequation which relates the mean fragment size obtained to the blast energy, hole size and rockcharacteristics.

Master of Science

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Abstract:

Metal plates are being replaced by lighter but equally strong laminated compositeplates in order to improve efficiency and increase performance of aerospace vehicles.But because of the complex construction of laminated plates they are very difficult toanalyze. Conventional thin plate theories prove to be inadequate in predicting laminatedcomposite plate behavior. Therefore, a finite element model which incorporates a first-order shear-deformation theory and nonlinear von Karman strains is described. Themodel is shown to accurately predict deflections in laminated composite plates due tononuniform transient heat fluxes and transverse mechanical loads.

Master of Science

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Abstract:

The Givens orthogonalization algorithm is an efficient alternative to the normal equations method for solving many adjustment problems in photogrammetry. The Givens method is one of a class of methods for solving linear systems known generally as orthogonalization or QR methods. It allows for sequential processing and greatly simplifies the computation of statistics on the observations and residuals. The underlying reason for these advantages is the immediate availability of the orthogonal Q matrix, which is computed as the data are processed and is intimately related to the statistics needed for blunder detection. One of these statistics, the F statistic computed from externally studentized residuals, is both easily obtained and well-suited for blunder detection.The Givens method requires nearly four times the number of computations as compared to the normal equations approach in order to reach a solution. However, depending on the size of the problem, blunder detection through the normal equations requires far more computer time than is required when starting with a Givens decomposition.The method allows a user to review intermediate results, test residuals and modify the solution without having to compute a full solution. Adjustments of a level net and a single-photo resection are used to demonstrate the method.Because of the advantage in computational time, the Givens method is superior to the normal equations approach when rigorous blunder detection is required.
Master of Science

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Abstract:

The purpose of this study was to explore issues related to the development ofpricing strategies. Important questions addressed included the importance of this topicand a description of how prices are set or why prices are set. Also, the concern ofwhether these issues are general across major types of pricing decisions, or specific tocertain pricing decisions was investigated. Particularly, this study reviewed thedescriptive survey research or case studies that have been done to determine howbusinesses make price decisions, and their key pricing policies and procedures.

While Korea is recognized as one of the most rapidly industrializing countries,marketing and marketing research have not been fully developed, and, furthermore, therehas been little research on pricing. Therefore, this study reports on a survey with 303Korean business people about their pricing attitudes and practices in order to obtaininformation about Korean businesses and help them improve their pricing strategies bysuggesting ideas based on price theory and previous price research.

The basic results of the survey indicate that although pricing has been generallyrecognized as an important area in marketing by Korean business people, it has not beenexamined as a way to influence demand in advanced market environments. While it isrevealed that Korean consumers are price sensitive and Korean business situations arecompetitive, Korean businesses seem to have offered similar products with a relativelyrigid pricing approach based on production costs. Their pricing strategies appear notto be related to the other elements of the marketing mix. However, promotional pricing,mainly as discounts, was regarded to be important to gain a competitive edge. In termsof actual price setting in industry and firms, many Korean businesses assume thecharacteristics of a price taker rather than price maker. Their primary short run pricingobjective was to meet existing competition. However, the major basis of their pricingpolicies was either competitive situation or pricing what the market will bear.

This study provides a general view on the type of issues that should be consideredin pricing, and evaluates the pricing practices of Korean businesses in comparison tothose of more advanced countries. The study is also of value to Korean business peoplebecause it offers them information on how prices are set in various industries, and theattitudes and opinions of business people about the pricing function.
Master of Science

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Adhesives and adheslvely bonded structures are being consideredas a viable alternative to conventional fastening methods. In order togain wider acceptance, it is essential to address the issue of themechanlcal characterizatlon of adhesive materials and itsimplementation in the design of bonded joints.

While measuring the in-situ properties of the adhesive ln a jointis a difficult task, characterizing its bulk properties is arelatively simpler undertaking. The objective of this study was topropose and verify an experimental procedure that would allow theanalytical prediction of the viscoelastic behaviour of a bonded joint, using bulk adhesive properties. The Arcan joint geometry waschosen because of the simple state of stress within the adhesive.

Master of Science

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