Laboratory report on sluice gate and hydraulic jump Coursework

Laboratory report on sluice gate and hydraulic jump - Coursework Example Generally, sluice gats are made up of a gate, a power mechanism and a frame and they are designed to withstand various water loads at different operating heights. There are two types of sluice gates. These are the wall-mounted sluice gates and the vertical rising sluice gates. For the vertical rising sluice gates, they are designed such that water flow is prevented as long as the water height does not exceed the gate height. In this types of sluice gates, the bottom and the side walls are sealed. For the wall-mounted sluice gates, also referred to as bottom sluice gates, passage of water is prevented to flow up to heights that exceed the gate. In this type, all the four sides of the sluice gates are sealed (Hager, 1992). As water flows in an open channel, it is only acted upon by atmospheric pressure implying that the gauge pressure is zero. In open channel flow, two flow depths exists, these are the subcritical flow and the supercritical flow (Khatsuria, 2004). The use of sluice in open channel alters the flow characteristics resulting in the flow changing from subcritical to supercritical. The flow rate under a sluice gate is illustrated by equation (1) below where by it is assumed that the flow is ideal (which is never the case in real situation). From the figure 1 above, it can be seen that flow under the sluice gate results into generation of a hydraulic jump just before the flow resumes back to subcritical flow from supercritical flow (Subramanya, 2009). As earlier connoted, a sluice gate changes flow from subcritical to supercritical flow. Under normal cases, the flow in an open channel is usually subcritical, therefore as the flow reverts back to sub-critical flow after passing through a sluice gate, there is sudden energy dissipation that results from the change of flow from supercritical to subcritical (Hager, 1992). This is the hydraulic jump. Where V is the velocity, is the

Economics of Slavery Essay Example | Topics and Well Written Essays - 500 words

Economics of Slavery - Essay Example Since an average slave hand could produce about a ton of tobacco yearly, the total increase in the tobacco trade over the century required an increase of about 70,000 hands, a minuscule fraction of the 5.7 million slaves imported during the same period. "As late as 1860 the average value of the capital invested in an American cotton textile factory was just $109,000 and the average number of employees was just 130" (Kolchin 1995, p. 24). Throughout the eighteenth century, the great slave plantations of the sugar colonies, with profits averaging about 10 percent on invested capital, were the largest privately owned enterprises of the age and their owners were among the richest of all men. The same can be said of the great cotton plantations in the United States on the eve of the Civil War (Kolchin, 1995). Alternative sources of labor were scarce; European labor was more expensive than African labor; Africans could endure the rigors of the tropics better than Europeans. While each of these factors played a role, no one of them individually, or their joint sum, constitutes an adequate explanation.