No description available.

No description available.

No description available.

A series of tests was performed in winter 1996 to measure degradation of paper mulches with the help of physical and mechanical properties. Four types of paper used for mulching, kraft paper gauge 40, 60 and 80 and waxed paper were laid over soil in two growth chambers. They were kept under observation for 27 days under controlled temperature, humidity and light. Mulches were sprayed with water to simulate rain. Tensile and puncture tests were performed on each type of paper every day. Four mechanical properties; stress, strain, energy and tensile energy absorption were calculated from the force-deformation curve obtained by tensile test. Two mechanical properties; displacement and force to break were calculated from the force-deformation curve obtained by puncture test. A special die had to be designed to perform puncture tests. This design eliminated shear loading which otherwise would have been present in normal puncture tests. / Results showed that paper - 3 (kraft paper gauge - 80) was best suited for mulching as the mechanical properties were stable through 27 days with negligible fluctuations. Waxed paper required less force to break but was stable through 27 days of experimentation. / A three-way factorial model was developed to analyze the results statistically. A SAS program was written to model the results. The fitted model was in very good agreement with the actual values.

No description available.

The main purpose of this study was to determine the effect of contour height on the passage ratio of pulp through screen apertures, and determine which operating variable has the greatest affect on screen performance. In addition, a freeness model was to be developed, in hopes of helping to predict the freeness drop between feed and accepts. The study was conducted at The University of British Columbia (UBC) using a laboratory scale pressure screen. Slot velocity, feed consistency and contour height were the changing variables. Samples were collected from which passage ratio, freeness, fibre length and coarseness were determined. From the studies conducted it was found that slot velocity had the greatest influence on the screen operation. As the slot velocity increased a greater force was applied to the fibre to help push it through the screen aperture. However, this increase in slot velocity decreases the fractionation ability (separation of fibres into different lengths) of the screen. The second most important variable was the contour height. The main function of the contour height is to disrupt the flow of thick stock at the wall of the screen and allow for unhindered movement of fibre to the screen wall. The greater the contour height is, the greater the passage ratio (pulp fibre passing through screen). However, there is a decrease in fractionation. The third most important factor was the feed consistency. At low feed consistencies there is less crowding in the screen. Less crowding leads to more loosely-formed flocs, which are easier for the contour height and the rotor to dissipate and thus leads to unhindered movement. Thicker feed stock has a negative effect on passage A Freeness model was developed that showed that freeness had a power law relationship to passage ratio. The passage ratio was raised to a constant B, which is a function of the contour height and the feed consistency.

Thesis (M.S.)--Virginia Polytechnic Institute. / Also available via the Internet.

Thesis (M.S.)--Rochester Institute of Technology, 1989. / Includes bibliographical references (leaves 50-51).

Thesis (Ph.D.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references (ℓ. 106-110)

Thesis (M.S.)--Rochester Institute of Technology, 1988. / Includes bibliographical references.