Thesis (M.S.)--University of Wisconsin--Madison, 1971. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

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A pneumatic harvesting method for jojoba seed was investigated. By constructing a stationary experimental unit, the motion of jojoba seeds and stones, which were close in size and weight to seeds, were examined under the effect of positive, negative, and a combination of both pressures. It was determined that there was a reasonable difference in the motion depending upon test conditions and head design. A vacuum head was designed based on the observations and data obtained from the experiments. Using this head it was possible to pick up jojoba seed without picking up stones. A nonstationary unit was constructed to examine the effect of ground speed on picking efficiency. Results showed that a cleaner harvest using a normal ground speed can be obtained with the new head than with conventional equipment. A blowing head was added to windrow seeds and increase the capacity of the machine. It was determined that when the two heads were used together harvesting field capacity increased, however reduced efficiency was found.

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The primary objective of this research is to develop a general modelling facility for modular pneumatic servo-drives. The component-oriented approach has been adopted as the modelling technique to provide the flexibility of modelling a wide variety of components and the segmentation of the non-linear system to less complex uncoupled component modules. A significant part of the research work has been devoted to identify a series of component modules of the single axis linear pneumatic servomechanism with standardised linking variables. The mathematical models have been implemented in a simulation software which produces time domain responses for design evaluation purposes. Alternative components for different servomechanism design were modelled as mutually exclusive modules which could be selected for assembly as if they were real physical entities. The philosophy of the approach was validated by tests on prototype servo-drives with matching components. Design analysis could be performed by simulating and comparing the performance of alternative system structures.

This paper details the redesign of a previous pneumatic motion system for a linear scanner to meet higher performance requirements. The previous design featured a scanner head, two air bearings, and two pneumatic cylinders and was intended to propel the scanner head back and forth in a linear motion at speeds up to 5 m/s. Air was supplied to the air bearings by tethering the scanner head to an air supply with plastic tubing. At speeds nearing 5 m/s, the tether began to oscillate violently and the repeated impacts of the scanner head and pneumatic cylinders caused the entire structure to vibrate. Also, large amounts of energy were lost due to momentum transfer between the scanner head and cylinders and friction within the cylinders themselves. Further, none of the energy of the impact was recovered. These problems were corrected by designing and purchasing new equipment and slightly altering the operation of the scanner. A system of needles was designed to provide air to the air bearings without the use of a tether. New pneumatic cylinders with exceptionally low friction were purchased and a method of precharging the air on the rod sides of the cylinders to a certain pressure was devised to add energy back into the system that is lost during operation. A special valve was designed to accomplish the addition of air into the precharge volumes. Also, a mechanism was designed to greatly minimize the vibration of the table. This structure consists of a large, suspended, inertial mass which holds the pneumatic cylinders so they are not actually mounted on the table which holds the scanning track.

Pneumatic conveyors have been used for the transportation of solids for many decades. Their design is substantially empirical, and because they run with almost no instrumentation or control, large safety factors are employed to ensure long-term safe and reliable conveying under all envisaged conveying conditions. The resulting excessive conveying velocity leads to increased energy consumption, pipeline wear and solids breakdown. The aim of the work reported in this thesis was to develop an instrumentation and control system which provides minimum cost conveying for a variable solids feedrate and composition, in a lean phase vertical pneumatic conveyor. Incipient blockage of the pipeline is detected through measuring solids velocity by cross correlation of signals from electrodynamic transducers. This solids velocity measurement system is modelled, and laser techniques independently confirm the experimentally measured solids velocity and profile in the pipe. A model of the pneumatic conveyor is described which is used in the design of a feedback control scheme. By controlling the pilot plant to convey at minimum safe solids velocity, independently of any solids feedrate change, energy savings of up to 45% are shown to be possible.

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