Week 8 Design: Radiation sensors should not be under the shadow of nearby obstructions, including instruments and vegeta

[answerhappygod]

Week 8 Design Radiation Sensors Should Not Be Under The Shadow Of Nearby Obstructions Including Instruments And Vegeta 1 (39.11 KiB) Viewed 32 times

Week 8 Design Radiation Sensors Should Not Be Under The Shadow Of Nearby Obstructions Including Instruments And Vegeta 2 (85.63 KiB) Viewed 32 times

Week 8 Design: Radiation sensors should not be under the shadow of nearby obstructions, including instruments and vegetation CO, and Ho Gas Analyzer Air temperature and humidity sensor mounted to the mast. Position it as far away as possible from nearby vegetation Phenocam mounted to mast Guidewires Rain gauge positioned out of the rain shadow of nearby obstacles and above vegetation Pits for the soil sensors Sensors can be installed in one or several pits, either close to or far from the tower, Figure 1. Eddy Covariance Flux Tower Radiometer Attachment to main tower frame with bracket co, and HD Gas Analyzer Figure 2. Birds-eye view of crossbeams
Figure 3. U-bolts and bracket used to attach crossbeams Design Description: The DOTW for Week 8 is a Eddy Covariance Flux Tower, Figure 1, which is used to directly observe the exchanges of gas, energy, and momentum between ecosystems and the atmosphere, across a range of environments and at potentially high windspeeds. The tower is stabilised by guidewires and a tripod base. As shown in Figure 2, the two primary sensors are attached to the tower using crossbeams and are at 90 degrees to each other. You may assume that the attachment between the tower post and crossbeams is a fixed support. Figure 3 shows how U-bolts have been used to attach the crossbeams to the main tower post, and you can assume that the bolts have been correctly tightened. Consider the forces acting on the tower, crossbeams, and guide ropes, and discuss their effects as guided by the following focus questions:
Focus Questions for Student Discussion: 1. Consider the crossbeams shown in Figure 2, what loads will each beam experience? What are the resulting stresses caused by these loads? 2. Consider the importance of the cross section of the crossbeams and what the effect on safety would be of using a solid vs tubular beam? What trade-offs do you envisage between practicality and factor of safety in this application? 3. Each crossbeam is mounted to the main tower post with a bracket secured by by U-bolt clamps, shown in Figure 3. What stresses would act within the U-bolts and what mode of failure would you envisage for these components ? 4. The stability of the central frame is increased through the use of guide wires, as shown in Figure 1. What forces are experienced by the guide wires? Are multiple wires necessary? What difference to the loads in the main shaft does the presence of the wires make? 5. Holes are drilled throughout the central post and crossbeams to allow the attachment of sensors and guidewires; how do these holes affect stresses within these beams? Are there locations where the presence of holes would be more problematic? What risks need to be considered when adding additional holes? 6. To obtain accurate measurements, the gas analyser needs to remain stable even within high wind conditions. What design parameters would need to be considered for the crossbeam to ensure accurate measurements? What design changes to the tower could be undertaken to further increase stability? 7. Flux towers are located across a range of environments which can include extremes such as desserts, alpine areas, and lakes. How should the range of operating conditions for the towers be considered when determining a choice of materials used?