Under sustained loads plain concrete and concrete members experience the phenomenon known as creep. Creep varies in rate and magnitude depending upon the nature and magnitude of load and upon the physical characteristics of the concrete. From a review of the literature, creep coefficients are studied as to how the values are affected by mixes, loadings, time, curing, and quality of aggregates and materials. Within the allowable working stress range of concrete, creep strain can be considered proportional to the induced stress. Assuming known stress - creep strain - time relations, a series of equations have been derived analytically to calculate the stress changes in both the steel and concrete in reinforced concrete beams of rectangular cross-section due to creep relaxation. The data has been tabulated and graphed. Extensive use of the digital computer has been made to thoroughly investigate these stress changes within a wide range of parameters including these stress changes within a wide range of parameters including magnitude of load, strength of concrete, geometric proportion of the beams, and the amount and type of reinforcing steel. / Master of Science

This investigation has been carried out for the purpose of determining the effect of solid particle size distribution on the roasting and leaching of a complex sulfide ore. The effect of pulp density in the leaching process has also been studied. The oxidizing roast of the combined sulfide concentrates, prepared by bulk sulfide flotation and tabling, was conducted with a fluidized-bed kiln. The calcines were leached by dilute sulfuric acid in an autoclave. The following conclusions have been reached: 1. In the fluidized-bed roasting, the solid particles within the size range of minus 35 to plus 150-mesh would have a higher overflow rate from the fluidized bed. This inference might be effective only when the roasting is conducted under the conditions performed in this investigation. 2. In the process combining fluidized-bed roasting and dilute sulfuric acid leaching, the effect of solid particle size is significant. The solid particles within the size range of minus 65 to plus 150-mesh have the highest iron recovery, the highest copper and zinc extraction rates and the lowest sulfur content of leach residue. 3. In dilute sulfuric acid leaching there is no significant effect of pulp density within the range tested in this investigation. The general trends are: iron recovery decreases as the pulp density decreases, extraction rates of copper and zinc decrease as pulp density increases, and there is little pulp density effect on the sulfur content of leach residue. / Master of Science

Moment Distribution Method was modified so that simple techniques applicable to symmetrical and anti-symmetrical frames may be applied to non-symmetrical rigid frames consisting of prismatic members. This approach simplifies considerably the calculations. Using the above approach, two different "Simplified Moment Distribution Methods" were introduced. Method No. l, an “exact” method, makes it possible to execute moment distribution in a single cycle. The “exact" values of the unknown moments are obtained by solving a set of simultaneous equations. This method is applicable to single-bay frames having an arbitrary number of stories. In the solution there is one unknown moment and one equation for each story. Method No. 2 simplifies the analysis of multiple-bay, multiple-story frames. It is a modified version of the standard moment distribution. Only half of the total number of joints has to be considered in this analysis and the convergence of the iteration process is accelerated. The presentation of the theory is preceded by the definition of a set of modified constants pertinent to the two methods. Illustrative examples for the analysis of single-bay as well as multiple-bay frames are included. / Master of Science

The processed meats operation of a typical Viiginia meat-packing firm was analyzed to investigate the possibilities of improving the operation. Linear programming was chosen as the analytical tool. Large firms in competing areas have adopted programming and found it profitable. Little information has been available relative to the usefulness of programming to the size of operations typical in Virginia. Least-cost ingredient mixes were developed for the various processed products. Optimum product combinations were ascertained under various conditional restraints. The marginal value products of restrictive resources were estimated. The possibility of improving the pattern of production was investigated and an optimum array of prices portrayed for an established operation. Regardless of the competitive situation faced by the firm, linear programming will be useful in decreasing the cost of the ingredient mixes and in directing the purchase of restrictive ingredients. The feasibility of adjusting an operation in accordance with an optimum product combination and/or an optimum array of prices will be determined largely by the competitive situation faced by a particular firm. Since no two firms operate under the same conditions or face the same competitive situation, the applicability of programming will therefore vary from firm to firm. The results suggest that programming can be an extremely valuable management tool for Virginia packers when used to suggest ways of decreasing operating costs and to provide guidelines for the many decisions involved in the production and sale of processed meats. / Master of Science

The flexural vibration of two incomplete circular rings, approximately 360º, fixed at one end and free at the other, is investigated. One ring lies in the thin ring range. The other ring lies in the borderline range between a thick and thin ring. A theoretical approach is used in an attempt to approximate the first three natural frequencies of the rings. These theoretical results are then compared with the results obtained from an experimental investigation. In an attempt to simplify the general equation of motion of the ring an assumption was made that the tangential inertia term had a negligible effect on the natural frequencies of a thin ring. The frequencies obtained from the resulting frequency equation were found to be poor approximations for the system. Good approximations were obtained for the first two frequencies of the thin ring, using the method of Rayleigh -Ritz. / Master of Science

Master of Science

Master of Science

A gamma scintillation spectrometer was assembled. and calibrated in a low background radiation area to analyze air samples. Air samples were taken from different locations in the physics building during reactor operation to determine the concentrations of A⁴¹ released to the surroundings of the building during reactor operation. The samples were collected in a one gallon polyethylene bottle with a 3 ¾” x 3 ¾” cylindrical well sealed in the bottom. The air samples were taken to the counting area and the sampling bottle placed on the detector, a 3” x 3" cylindrical NaI(TI) crystal which fitted into the well. The pulses from the detector were fed te a multi-channel analyzer. From the number of pulses per unit time under the photo-peak, the concentration of A⁴¹ for each location was determined. Samples were analyzed for 4, 7, and 10 kw from which a linear extrapolation was made to estimate the concentrations of A⁴¹ in these locations if higher power operation is authorized. / Master of Science

M.S.

Thesis (MMus) -- University of Stellenbosch, 2004. / ENGLISH ABSTRACT: This dissertation is an account of Paul Hindemith's life between 1919 and 1939 with special reference to his compositional development through the three sonatas for viola and piano. The introduction to the dissertation initially provides a list of Hindemith's vast output for the viola followed by insight into the reason and need for undertaking this research, literary sources used and their function in the context of this study and the conclusion that there is a lack of extant research on the three sonatas for viola and piano. This is followed by comments on Hindemith as a viola player and composer, supported by opinions of scholars and performers. An overview of the contents and aim of the dissertation completes the introduction. This first of the two comprehensive chapters briefly discusses Hindemith's character traits as viewed by a number of scholars and continues by introducing the political, social and financial circumstances in Germany in 1919. The chapter progresses into a division of the period 1919-1939 into six sub-sections of dates within this time span. Each section focuses on the political, financial and musical circumstances in Hindemith's life, with special attention given to the periods of greatest change and conflict. Included in this chapter are also the specific circumstances surrounding the composition, first performances and publication of the three sonatas for viola and piano, alongside mention of other works written at the same time. This is supported by references and quotations from correspondence between Hindemith and his wife, colleagues and friends, as well as translations of newspaper articles, letters and articles which thus far have not been translated into English. Special attention is given to possible reasons for the late publication of op.25 no.4 in 1977. Chapter 2 looks deeper into the significance, success and development of Hindemith through these three works. His stylistic development beginning with the influences of Debussy and Reger, his identification with the 'Neue Sachlichkeit' until the beginning of his later conservatism can be seen clearly in these three works. The aim of the study is to assimilate the available information into an accurate and coherent picture of the composer's life and stylistic development between 1919 and 1939 in a way that has not been presented before. It is my intention through this work that the unique style of the sonatas as well as their important place in the viola repertoire is apparent, and consequently of interest to other viola players, hopefully encouraging them to play the works themselves. / AFRIKAANSE OPSOMMING: In hierdie tesis word Paul Hindemith se lewe tussen 1919 en 1939 beskryf, met spesiale verwysing na sy ontwikkeling as komponis soos dit waargeneem kan word in die drie sonates vir altviool en klavier. Die inleiding tot die tesis verskaf 'n lys van Hindemith se omvangryke oeuvre vir die altviool, gevolg deur 'n motivering waarom hierdie studie onderneem word. Die omvattende literatuurstudie dui daarop dat daar tot op datum baie min navorsing oor die drie altvioolsonates gedoen is. Vervolgens word kommentaar gelewer op Hindemith as altviolis en komponis, ondersteun deur opinies van uitvoerende kunstenaars en musikoloë. 'n Oorsig oor die inhoud en die doelstellings van die tesis sluit die inleiding af. Die eerste van die twee omvattende hoofstukke begin met 'n bespreking van Hindemith se karakter, gevolg deur 'n oorsig oor die politieke, sosiale en ekonomiese omstandighede in Duitsland rondom 1919. Die tydperk 1919-1939 word dan in ses onderafdelings verdeel. Elke onderafdeling plaas die fokus op spesifieke politieke, finansiële en musikale omstandighede in Hindemith se lewe. Die jare waarin konflik en verandering op besondere wyse na vore tree word meer omvattend bespreek. Teen die agtergrond van ander werke uit hierdie tyd word die spesifieke omstandighede rondom die komposisie, eerste uitvoering en publikasie van die drie altvioolsonates in detail beskryf. Dit word aangevul deur verwysings na en aanhalings uit korrespondensie tussen Hindemith en sy vrou, kollegas en vriende, sowel as deur vertalings van koerantartikels en briewe wat tot dusver nog nie in Engels beskikbaar was nie. Hoofstuk 2 plaas die klem op Hindemith se stilistiese ontwikkeling, soos dit in the drie sonates waargeneem word. Die sonates illustreer Hindemith se ontwikkeling vanaf sy bewondering vir Debussy en Reger, oor sy vereenselwiging met die ideale van die 'Neue Sachlichkeit' tot by die meer konservatiewe benadering wat hy later gevolg het. Hierdeur word gepoog om die unieke waarde van die sonates, asook die belangrike plek wat hulle in die algemene altvioolrepertorium beklee, te beskryf. Hopelik sal die studie die belangstelling van altvioliste wek en hulle aanmoedig om die werke ook self te speel. Die doel van die studie is dus om die beskikbare inligting tot 'n samehangende en akkurate beeld van die komponis se lewe en stilistiese ontwikkeling tussen 1919 en 1939 te voeg op 'n wyse wat nog nie voorheen gedoen is nie. Hierdeur word gepoog om die unieke waarde van die sonates asook die belangrike plek wat hulle in die algemene altvioolrepertorium beklee, te beskryf. Hopelik sal die studie die belangstelling van altvioliste wek en hulle aanmoedig om die werke ook self te speel.