No description available.

This report will demonstrate the design techniques to translate a given scanning algorithm into a hardwired pre-processor. The language to be "pre-processed" is TRAC (Text Reckoning and Compiling) devised by Mooers and Deutsch. The major drawback in the current implementation of TRAC is speed. The software overhead required for string manipulations and execution of the input scanning algorithm is the major degrading factor. A TRAC machine consisting of a hardwired pre-processor to scan the input and produce formatted data for a stack oriented evaluator is proposed. The control machine for the input scanning algorithm for the pre-processor is designed using various sequential machine design techniques. The one-hot code and the minimum state variable design represent the two extremes which are presented.

M.S.

M.S.

M.S.

M.S.

A series of tests was run to determine the performance characteristics of the 2-1/2 ton steam jet refrigeration unit. The first series of tests was run to determine the nozzle position relative to the throat of the diffuser at which best performance was obtained. This series included tests with two methods of introducing the warm water into the evaporator, namely by spraying the warm water into the evaporator by means of commercial spray nozzles and by spraying the warm water into the evaporator through small holes in a straight piece of pipe. A series of tests was run to determine the effect of the evaporator water level on performance. A series of tests was also run with inlet steam pressures lower and higher than design in combination with outlet pressures at and lower than design. Lastly, one test was run in an effort to reduce the amount of liquid carryover into the ejector. From the results of the above tests the following was concluded: 1. Use of a 62% entrainment efficiency and a 65% diffuser efficiency to give a greater steam flow rate did not enable the design capacity to be met. 2. Best performance of the unit was obtained with the nozzle exit 7-1/2 inches from the entrance to the diffuser throat. 3. Better performance was obtained from the unit by introducing the wara water into the evaporator by means of the commercial spray nozzles than was obtained by introducing the warm water into the evaporator by means of small hole in a straight pipe. 4. Lowering the evaporator water level did not effect performance of the unit greatly. However, control of the unit was greatly enhanced by using a low evaporator water level. 5. Performance of the unit was unstable at inlet steam pressures above design and outlet pressure below design. The capacity of the unit dropped sharply under these condition 6. The design evaporator outlet velocity was too high to enable a sufficiently large amount of liquid carryover to be baffled out. 7. The compression process in the diffuser did not occur as assumed in the design procedure. 8. The throat area of the diffuser should be increased to reduce the fluid velocity in the throat and thereby improve performance of the unit. This is necessary to make the normal shock occur at the throat section of the diffuser. / M.S.

A whole-stalk harvester was developed as part of a sweet sorghum-for-ethanol production system. Gathering chains grasped the stalks as they were cut at the base with a disk-cutter. These stalks were flipped onto a cross conveyor and deposited into an accumulator. Periodically the machine stopped and the accumulator was dumped. All the components on the harvester are powered hydraulically. Five pumps on the harvester supply flow to seven actuator circuits. Power is delivered to the pumps from the tractor PTO via a universal joint driveline. Each of the six existing circuits and one proposed circuit were modeled with bond graphs and implemented for computer analysis using TUTSIM. Model validation was done by comparing simulated and measured driveline torque, line pressure, and return line flow rate in each of the six existing circuits. Data collected on the gathering chains circuit was used to analyze the effect of driveline joint angles on transmitted torque and pump output. Torque measurements at three driveline angles showed a torsional vibration with a primary harmonic at driveline rpm and a secondary at twice driveline rpm. A combination of Cardan joint characteristics, mass unbalance, the secondary couple, and non-linear driveline and V-belt stiffness was used to model the driveline. Resulting simulated torque emulated the experimental very well. Measured pressure in the gathering chains circuit showed relatively low fluctuations at the highest amplitude torsional vibration (highest driveline joint angles). It was concluded that driveline vibration would not significantly affect the gathering chains circuit performance. The cross-conveyor motor circuit simulation showed close agreement to experimental results. Mean predicted flow, pressure, and torque were within 8.9, 7.3, and 7.7 percent of mean measured values. A simulation with a stalk load on the conveyor showed that power requirement increased only 8.0 percent. The accumulator dump circuit was analyzed to determine if the load on the motor would become over-running and cavitate the pump or motor as the stalks were being dumped. Simulation showed that a bundle up to 300 kg could be dumped without over-running the motor, and since this was a larger bundle than the bin could hold, a design modification was not necessary. The disk-cutter circuit was designed based on simulation results for several combinations of motor, pump, and sheave ratio. A 7.3 cm³/rad motor, 2.53 cm³/rad pump , and 2:1 sheave ratio produced the correct disk-cutter speed, and low torsional vibration when cutting the stalks, consequently this combination was selected for the design. / Ph. D.

Thesis (MEng (Mechanical Engineering))--University of Stellenbosch, 1994. / 213 leaves printed on single pages, preliminary pages i-xix and numbered pages 1-116. Includes bibliography, list of tables, list of figures and nomenclature. / Digitized at 600 dpi grayscale to pdf format (OCR), using a Bizhub 250 Konica Minolta Scanner. / ENGLISH ABSTRACT: A design methodology for low pressure rise, rotor only, ducted axial flow fans is formulated, implemented and validated using the operating point specifications of a 1/6th scale model fan as a reference. Two experimental fans are designed by means of the design procedure and tested in accordance with British Standards 848, Type A. The design procedure makes use of the simple radial equilibrium equations, embodied in a suite of computer programs. The experimental fans have the same hub-tip ratio and vortex distribution, but differ in the profile section used. The first design utilises the well known Clark-Y aerofoil profile whilst the second takes advantage of the high lift characteristics of the more modern NASA LS series. The characteristics of the two designs are measured over the entire operating envelope and compared to the reference fan from which the utility and accuracy of the design procedure is assessed. The performance of the experimental fans compares well with both the reference fan as well as the design intent. / AFRIKAANSE OPSOMMING: 'n Ontwerpmetode vir lae drukstyging, enkel rotor aksiaal waaiers is geformuleer, toegepas en bevestig deur gebruik te maak van die ontwerppunt spesifikasies van 'n 1/6 skaal verwysingswaaier. Twee eksperimentele waaiers is ontwerp deur middel van die ontwerpmetode en getoets volgens die BS 848, Type A kode. Die ontwerpmetode maak gebruik van die eenvoudig radiale ewewigsvergelykings en 'n stel rekenaarprogramme. Die twee eksperimentele waaiers het dieselfde naaf-huls verhouding en werwel verdeling, maar verskil daarin dat verskillende vleuelprofiele gebruik is vir elkeen van die twee waaiers. Die eerste ontwerp maak gebruik van die bekende Clark-Y profiel terwyl die tweede die moderne NASA LS profiel gebruik. Die karakteristieke van die twee eksperimentele waaiers is gemeet oor die hele werkbereik en vergelyk met die verwysings waaier waardeur die geldigheid en akkuraatheid van die ontwerpmetode bepaal is. Die werkverigting van die eksperimentele waaiers vergelyk goed met die verwysingswaaier en bevredig die ontwerpsdoelwitte.

Thesis. 1977. B.S.--Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaf 84. / B.S.