Computer Control Of Processes By M Chidambaram Pdf Download BEST
The design of these complex systems is multidisciplinary in nature and encompasses mechanical, process control, and instrumentation engineering. Invariably, the state-of-the-art autoclave systems are completely automated with reliable computer control systems.
Computer Control Of Processes By M Chidambaram Pdf Download
In auto mode of execution, operator can choose the required cure cycle (or program a new one) and command the system to execute it. In the event of computer failure, which can occur at any time during the cure without a warning, the semi-auto mode provides a very useful fallback arrangement. In this mode, operator can feed the set points for temperature, pressure, and vacuum directly to the respective controller and initiate the segments of the cure cycle such as heat, pressure, and vacuum cycle. Figure 9 shows the Architecture of the control system developed for the large autoclave.
The control system consists of programmable PID (proportional-integral-derivative) controllers for effecting the closed-loop control of temperature, pressure, and vacuum; Recorders for the display, plot, and storage of all the analog input signals such as part temperature at different locations, pressure, vacuum at different parts, and so forth; PLC (programmable logic controller) for ensuring safety, interlocks, sequential operation, status/alarm display, and so forth. All these components are connected to a pair of serial device servers (for redundancy) and in turn accessed by the computers through Ethernet links. The communication links used in the autoclave system include RS485, USB, and ethernet . Design drivers of the control system as already stated are:(i)reliability and redundancy,(ii)fail Safe,(iii)ease of operation and maintenance.
Microsoft Visual Studio is one of the popular platforms for the autoclave software development. The software performs the general functions of SCADA (supervisory control and data acquisition), in addition to carrying out job-temperature control. Protocols and tools used in the software include MODBUS, TCP-IP, OPC (OLE for process control) Client-Server routines, data integrity check through CRC (cyclic redundancy check), and so forth. Another unique feature is the automatic takeover of control by the slave computer in case of problem in the master computer. This is achieved by the automatic tracking of the user-specified cure cycle, control parameters, and the current state of the process through the slave computer.
A report by the United Nations Environment Management Group lists key processes and agreements made by various organizations globally in an effort to manage and control e-waste. Details about the policies could be retrieved in the links below.
Guiyu in the Guangdong region of China is a massive electronic waste processing community. It is often referred to as the "e-waste capital of the world." Traditionally, Guiyu was an agricultural community; however, in the mid-1990s it transformed into an e-waste recycling center involving over 75% of the local households and an additional 100,000 migrant workers. Thousands of individual workshops employ laborers to snip cables, pry chips from circuit boards, grind plastic computer cases into particles, and dip circuit boards in acid baths to dissolve the precious metals. Others work to strip insulation from all wiring in an attempt to salvage tiny amounts of copper wire. Uncontrolled burning, disassembly, and disposal has led to a number of environmental problems such as groundwater contamination, atmospheric pollution, and water pollution either by immediate discharge or from surface runoff (especially near coastal areas), as well as health problems including occupational safety and health effects among those directly and indirectly involved, due to the methods of processing the waste.