Guide To Learn
Before the development of CAD, the manufacturing world adopted tools controlled by numbers and letters for manufacturing complex shapes in an accurate and repeatable manner. During 1950s, these numerically controlled (NC) machines used the existing technology of paper tapes with regularly spaced holes punched in them to feed numbers into controller machines that were wired […]
Since 1980, the development of readily affordable CAD programs that could be run on personal computers began a trend of massive downsizing in drafting departments in many small- to mid-size companies. As a general rule, one CAD operator could readily replace at least three to five drafters using traditional methods. Additionally, many engineers began to […]
Most CAD computers are Windows based PCs. Some CAD systems also run on one of the Unix operating systems and with Linux operating systems. Some CAD systems such as QCad, NX or CATIA V5 provide multiplatform support including Windows, Linux, UNIX and Mac OS X. Generally, no special hardware is required with the possible exception […]
Computer-aided design or CAD is a technique of design of objects, which is real or virtual with the help of computer technology. The design of geometric models for object shapes, in particular, is often called computer-aided geometric design (CAGD). In the manual drafting of technical and engineering drawings, the output of CAD often must convey […]
There are different types of weirs. It may be a simple metal plate with a V-notch cut into it, or it may be a concrete and steel structure across the bed of a river. A weir that causes a large change of water level behind it, compared to the error inherent in the depth measurement […]
Weirs are used in conjunction with locks, to render a river navigable and to provide even flow for navigation. In this case, the weir is made significantly longer than the width of the river by forming it in a ‘U’ shape or running it diagonally, instead of the short perpendicular path. Since the weir is […]
A weir, also known as a low-head dam is a small overflow-type dam commonly used to raise the level of a river or stream. Weirs have traditionally been used to create mill ponds in such places. Water flows over the top of a weir, although some weirs have sluice gates, which release water at a […]
Construction of a hydroelectric plant requires a long lead time for site studies, hydrological studies and environmental impact assessment, and are large-scale projects by comparison to traditional power generation based upon fossil fuels. The number of sites that can be economically developed for hydroelectric production is limited; new sites tend to be far from population […]
The impact on human society is also significant. For example, the Three Gorges Dam on the Yangtze River in China will create a reservoir 600 km long, to be used for hydro-power generation. Its construction required the loss of over a million people’s homes and their mass relocation, the loss of many valuable archaeological and […]
Impact is assessed in several ways: A large dam can cause the loss of entire ecospheres, including endangered and undiscovered species in the area, and the replacement of the original environment by a new inland lake.