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Fluid Journal : Fall 2014
9 The Fluid Journal Fall 2014 TE SE= -- A where SE is the specific energy (J/ mm2), TE is the total energy (J), and A is the wheat straw wall area at failure cross-section (mm2). Twenty-five wheat straws from each plot were tested for shear stress and specific energy. During the shearing test, shear force was recorded by the computer. Shear force versus center movement was then graphed (Figure 3). From Figure 3 the highest load was reported by the computer, which was also the shearing force (F) of the wheat straw where it breaks. Integration, the area between load and extension from zero to breaking point, is the total energy (TE) demanded by cutting through the wheat straw. To accurately measure the cross- sectioned area at the breaking point of wheat straw, a microscope and camera were used to capture images of the cross-sectional area of wheat straw. The pictures were then analyzed with the software SigmaScan 5. Figure 4 shows the wheat straw captured by a microscope (left) and then analyzed with the software for area (right). Data were statistically analyzed through SAS 9.3 software and summarized. MIXED and GLM procedures were applied to analyze the data. Data analysis Three sample periods were conducted in this experiment. In 2012, samples were collected from all three sites during summer months. In 2013, to better stimulate cultivation season, two sampling periods were conducted. They were in June and October 2013, respectively. By January of 2014, all field work and lab work were completed. Data analysis is in process. In this report we will focus on the summer of 2012 sampling. It will include physical parameters, as well as: • Aboveground biomass • Shear stress • Specific energy. In the experimental design we considered two factors. They were treatment and timing. Using GMS and Figure 3. Shear force along blade movement recorded by computer with different colors showing different shearing stages. Figure 4. Image of cross section of wheat straw at breaking point under microscope and being analyzed by SigmaScan 5 software. Figure 2. Testing wheat straw physical strength using a shear box attached with load cell that connected with a computer.